JP2011119505A - Method of mounting semiconductor device - Google Patents

Abstract

Problems that occur when a semiconductor device is mounted on a mounting substrate via solder balls (solder paste and ball-shaped external terminals supplied to the semiconductor device are not fused, solder ball bridges, and solder ball balls To improve the mounting yield of the semiconductor device.
The amount of warping of the first BGA 10a is measured in advance by a first analysis, and a calibration curve (relation between the shape and load) relating to the shape of a solder ball (conduction path) 13 is calculated by a second analysis. Based on the results of the first and second analyses, the optimum amount of solder paste (solder paste for semiconductor device) is calculated, and then solder paste (semiconductor device bump land) 3 is applied to each bump land (semiconductor device bump land) 3. By supplying the device solder paste, problems that occur when the first BGA 10a is mounted on the first main surface 1x of the mounting substrate 1 are prevented.
[Selection] Figure 18

Description

  The present invention relates to a semiconductor device mounting technique, and more particularly to a technique effectively applied to a mounting method in which a semiconductor device having ball-shaped external terminals is soldered to a mounting substrate via the external terminals.

  For example, in Japanese Patent Application Laid-Open No. 2007-88293 (Patent Document 1), in order to reduce the warpage of the substrate when the electronic component is soldered and mounted on the substrate, the mounting of the electronic component is desired to reduce the warpage of the substrate. A method of joining a warp reducing member to a portion corresponding to the back surface of a region is disclosed. It is described that the warp reducing member has an outer dimension substantially equal to the outer dimension of the electronic component and is bonded to the substrate by a bonding material having a melting point lower than that of the solder connection portion of the electronic component. Further, it is described that the warpage reducing member is mounted on the substrate in the same process as the solder mounting process of other electronic components.

JP 2007-88293 A

  A BGA (Ball Grid Array) is a semiconductor device in which small ball-shaped external terminals made of solder (hereinafter referred to as solder balls (BGA balls)) are arranged in a lattice pattern. The BGA can be provided with a large number of solder balls (BGA balls), and the mounting area can be reduced because the solder balls (BGA balls) do not protrude from the periphery of the BGA in plan view.

  However, the BGA has a package structure in which, for example, a semiconductor chip made of a silicon substrate is mounted on a wiring board made of glass epoxy resin, and the semiconductor chip is sealed with epoxy resin. A plurality of solder balls (BGA balls) are mounted on the lower surface of the wiring board. Thus, since BGA is comprised with various materials, when heat | fever is applied with respect to BGA, curvature will arise throughout BGA. Therefore, in the process of mounting the BGA on the mounting substrate, there are various technical problems due to the warpage of the BGA described below.

  (1) Solder paste (solder paste for semiconductor device) and solder printed on the surface of bump lands (bump lands for semiconductor device) formed exposed on the first main surface (upper surface, surface) of the mounting substrate Unfused with ball (BGA ball).

  As shown in FIG. 27A, when the BGA 10 is mounted on the mounting substrate 1, solder paste 8 printed on the surfaces of the plurality of bump lands 3 formed exposed on the main surface of the mounting substrate 1, A solder ball (BGA ball) 12 supplied to the BGA 10 is brought into contact. Subsequently, by performing a reflow process at a temperature of 230 to 240 ° C., the solder paste 8 and the solder ball (BGA ball) 12 are integrated to form one solder ball (conduction path) 13. The solder ball (conduction path) 13 is an integration of the solder paste 8 and the solder ball (BGA ball) 12 and is distinguished from the solder ball (BGA ball) 12 supplied to the BGA 10. The BGA 10 is mounted on the mounting substrate 1 by this soldering.

  However, as shown in FIG. 27 (b), when the central portion of the BGA 10 warps in a concave shape protruding in the back surface direction in the reflow process, the solder balls (BGA balls) 12 and the solder paste arranged in the inner region of the BGA 10 are used. Even if it contacts 8, the solder ball (BGA ball) 12 arranged in the outer peripheral area of the BGA 10 and the solder paste 8 may not contact each other. If the solder ball (BGA ball) 12 is weakly pressed into the solder paste 8 even if the solder ball (BGA ball) 12 and the solder paste 8 come into contact with each other, as shown in FIG. Film (for example, oxide film) may remain, and the solder paste 8 and the solder ball (BGA ball) 12 may not melt. When such a fusion of the solder paste 8 and the solder ball (BGA ball) 12 occurs, the solder paste 8 and the solder ball (BGA ball) 12 are not integrated, and an electrical high resistance or non-resistance is generated in this portion. Conduction will occur.

  In particular, the unfused solder paste 8 and the solder ball (BGA ball) 12 are, as shown in FIG. 27C, solder balls (BGA balls) located at the four corners of the outermost periphery shown in black. ) 12 is likely to occur.

  (2) Solder paste (solder paste for semiconductor devices) printed on the surface of a plurality of bump lands (bump lands for semiconductor devices) formed exposed on the first main surface (upper surface, surface) of the mounting substrate A solder ball (conduction path) bridge formed by fusing a solder ball (BGA ball).

  As shown in FIG. 29A, when the BGA 10 is mounted on the mounting substrate 1, the solder paste 8 printed on the surface of the plurality of bump lands 3 formed on the first main surface of the mounting substrate 1 is exposed. Then, the solder balls (BGA balls) 12 supplied to the BGA 10 are brought into contact with each other. Subsequently, by performing a reflow process at a temperature of 230 to 240 ° C., the solder paste 8 and the solder ball (BGA ball) 12 are integrated to form one solder ball (conduction path) 13. The BGA 10 is mounted on the mounting substrate 1 by this soldering.

  However, as shown in FIG. 29B, when the central portion of the BGA 10 warps in a convex shape protruding in the surface direction in the reflow process, the solder balls (conduction paths) 13 formed in the outer peripheral area of the BGA 10 are crushed. As a result, adjacent solder balls (conduction paths) 13 are connected to each other. When such a bridge of the solder balls (conduction paths) 13 occurs, an electrical short circuit occurs at this portion.

  In particular, as shown in FIG. 29C, the bridges of the solder balls (conduction paths) 13 are solder balls (BGA balls) 12 located at two corners on the outermost periphery shown in black, which are diagonally opposed to each other. It is easy to occur in.

  (3) After mounting the BGA on the first main surface (upper surface, front surface) of the mounting substrate, another BGA is mounted on the second main surface (lower surface, rear surface) located on the opposite side of the first main surface of the mounting substrate. When this occurs, the solder balls (conduction paths) that occur in the BGA previously mounted on the first main surface of the mounting substrate are dropped.

  The process of mounting the first BGA 10x and the second BGA 10y on the first main surface (upper surface, front surface) 1x and the second main surface (lower surface, back surface) 1y of the mounting substrate 1 is performed, for example, according to the following procedure. First, as shown in FIG. 30A, the solder paste printed on the surfaces of the plurality of bump lands 3 formed on the first main surface 1x of the mounting substrate 1 and the solder balls ( A BGA ball). Subsequently, the first BGA 10x is mounted on the first main surface 1x of the mounting substrate 1 by the first soldering. Next, similarly, the solder paste 26 printed on the surfaces of the plurality of bump lands 5 formed on the second main surface 1y of the mounting substrate 1, and the solder balls (BGA balls) 12y supplied to the second BGA 10y. And contact. Subsequently, the second BGA 10y is mounted on the second main surface 1y of the mounting substrate 1 by the second soldering.

  However, as shown in FIG. 30B, in the second soldering reflow process, the solder balls (conduction paths) 13 formed in the inner region of the first BGA 10x are disengaged from the bump lands provided in the first BGA 10x. Sometimes. Although not shown, the solder ball (conduction path) 13 may be detached from the bump land 3 of the mounting substrate 1.

  This is considered to be due to the phenomenon described below.

  When the solder ball (conduction path) 13 is solidified in the first soldering, the first BGA 10 x is fixed to the mounting substrate 1 by the solder ball (conduction path) 13. At this time, the first BGA 10x exhibits a warp corresponding to the conditions at this time such as the characteristics of the constituent materials and the temperature distribution. This warping is maintained thereafter until the solder ball (conduction path) 13 is melted and released from the restraint.

  Next, when the solder ball (conduction path) 13 is melted in the second soldering, the first BGA 10x is not restrained by the remelting of the solder ball (conduction path) 13, and as shown in FIG. It exhibits warpage that matches the conditions at this time, such as the characteristics of the constituent materials and the temperature distribution. Conditions such as characteristics of the constituent materials and temperature distribution when the solder ball (conduction path) 13 solidifies in the first soldering, and configuration when the solder ball (conduction path) 13 remelts in the second soldering Conditions such as material properties and temperature distribution do not match. Therefore, in the first BGA 10x, when the solder ball (conduction path) 13 is remelted in the second soldering, the amount of warpage is changed compared to when the solder ball (conduction path) 13 is solidified in the first soldering. . This change in the warping amount may increase the convex shape, and a movement of separating the bump lands provided on the first BGA 10x and the bump lands 3 provided on the mounting substrate 1 occurs inside the first BGA 10x.

  Also, the solder balls (conduction paths) 13 at the time of the second soldering are melted in the order from the periphery of the first BGA 10x to the inside from the heat supplied from the reflow device and the positional relationship between the mounting substrate 1 and the first BGA 10x. I will do it. This is because the reflow process described above is performed in a state in which the mounting substrate 1 on which the first BGA 10x is mounted is disposed inside the reflow furnace provided in the reflow apparatus. Therefore, the solder ball (conduction path) 13 arranged inside the first BGA 10x is delayed in timing as compared with the solder ball (conduction path) 13 arranged outside the first BGA 10x. As time of the reflow process passes, the stress (stress acting in the peeling direction) generated at the joint between the solder ball (conduction path) 13 disposed on the inner side and the bump / land 3 also increases, and the inner solder ball ( When the conduction path 13 is melted, the joining state is released all at once, so that the joint is not gradually deformed like the outer solder ball (conduction path) 13 and the joint cannot be maintained, and breakage occurs.

  Therefore, the ball drop of the solder ball (conduction path) 13 is likely to occur in the solder ball (BGA ball) 12 located in the inner region of the first BGA 10x shown in black, as shown in FIG.

  Further, the ease of peeling of the solder balls (conduction paths) 13 depends on the amount of change in warpage, and further changes in characteristics (for example, glass transition temperature) due to differences in heat history of soldering of constituent materials and moisture absorption during storage. It is affected by a difference in temperature distribution during solidification of solder in the first soldering and temperature distribution during remelting of solder in the second soldering.

  As described above, in the BGA mounting process, the solder paste and the solder ball (BGA ball) are not fused due to the warpage of the BGA, the bridge of the solder ball (conduction path), and the ball drop of the solder ball (conduction path). Problems occur. However, the factors affecting these phenomena are the pitch of the solder balls (BGA balls), the arrangement of the solder balls (BGA balls), the weight of the BGA, the supply amount of the solder paste, the temperature and atmosphere of the reflow process, and the temperature of the BGA. The distribution is diverse. Therefore, it is difficult to narrow down values suitable for these various factors, and it is difficult to solve all the various problems described above.

  Patent Document 1 described above discloses a mounting substrate warpage reduction structure and a mounting substrate warpage reduction method capable of reducing the warpage of the mounting substrate when electronic components are soldered and mounted on the upper and lower surfaces of the mounting substrate. However, the mounting substrate warpage reduction structure and the mounting substrate warpage reduction method cannot be applied when the BGA itself is warped. Further, for example, unfused solder paste and solder balls (BGA balls) and a bridge of solder balls (conduction paths) occur even when an electronic component is mounted only on the upper surface of the mounting substrate. The mounting substrate warpage reduction structure and the mounting substrate warpage reduction method cannot be applied.

  SUMMARY OF THE INVENTION An object of the present invention is to cause a defect that occurs when a semiconductor device is mounted on a mounting substrate via a solder ball (conduction path) (a solder paste and a ball-shaped external terminal supplied to the semiconductor device (solder ball (BGA ball)). And a solder ball (conducting path) bridge and a solder ball (conducting path) ball drop), and a technique capable of improving the mounting yield of the semiconductor device.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  That is, in the semiconductor device mounting method of the present invention, the amount of warpage of the semiconductor device is measured in advance by a first analysis, and further, a calibration curve relating to the shape of a solder ball (conduction path) is obtained by a second analysis (the relationship between shape and load). ) And the optimal supply amount of solder paste is calculated based on the results of the first and second analyses, and then the solder paste is supplied to each of a plurality of bump lands.

  Among the inventions disclosed in the present application, effects obtained by one embodiment of a representative one will be briefly described as follows.

  Problems that occur when a semiconductor device is mounted on a mounting substrate via a solder ball (conduction path), for example, unfusion of solder paste and ball-shaped external terminals (solder balls (BGA balls)) supplied to the semiconductor device, It is possible to improve the mounting yield of the semiconductor device by preventing the solder balls (conduction paths) from bridging and the solder balls (conduction paths) from falling off.

It is process drawing explaining the mounting procedure of the semiconductor device by Embodiment 1 of this invention. It is principal part sectional drawing of the electronic device explaining the mounting process of the semiconductor device by Embodiment 1 of this invention. FIG. 3 is an essential part cross-sectional view of the same portion as that in FIG. 2 of the electronic device during a manufacturing step following that of FIG. 2; It is process drawing which calculates the supply amount of the solder paste by Embodiment 1 of this invention. It is a schematic diagram explaining the high temperature curvature measuring method of BGA by Embodiment 1 of this invention. It is a back view (arrangement figure of the solder ball (BGA ball) supplied to the back) showing the measurement range of the high temperature warpage of BGA by Embodiment 1 of the present invention. It is a graph which shows a time-dependent change of the high temperature curvature of BGA by Embodiment 1 of this invention. (A) and (b) are an example of a plurality of solder balls (BGA balls) arranged on the back surface of the first BGA and a plurality of solder balls arranged on the back surface of the second BGA according to Embodiment 1 of the present invention, respectively. It is an arrangement diagram of (BGA ball). It is a schematic diagram which shows the shape of BGA in each temperature (room temperature before temperature rising, preheating temperature, solder melting temperature, and reflow maximum temperature) of the BGA according to Embodiment 1 of the present invention. (A), (b), and (c) are schematic diagrams each showing a connection portion between the mounting board and the BGA according to the first embodiment of the present invention with solder balls (conduction paths), and the connection between the mounting board and the BGA. It is the schematic diagram which represented the part with the spring, and the schematic diagram of the solder ball (conduction path) explaining the parameter used for an analysis model. It is a graph which shows an example of the relationship between the height of one solder ball (conduction path) calculated using the analysis model by Embodiment 1 of this invention, and the load which one solder ball (conduction path) bears. . The height of one solder ball (conduction path) and the width of one solder ball (conduction path) when the volume of the solder ball (conduction path) calculated using the analysis model according to Embodiment 1 of the present invention is constant It is a graph which shows an example of a relationship. It is a schematic diagram explaining the overlap amount of the solder paste and solder ball (BGA ball) by Embodiment 1 of this invention. (A) and (b) are an arrangement diagram of a plurality of bump lands formed on the first main surface of the mounting substrate in the region where the first BGA according to the first embodiment of the present invention is mounted, and the second BGA is mounted. FIG. 6 is an array diagram of a plurality of bump lands formed on the first main surface of the mounting substrate in a region to be mounted. (A) And (b) is a top view of the printing mask which opposes the area | region where 1st BGA by Embodiment 1 of this invention is mounted, respectively, and the printing mask which opposes the area | region where 2nd BGA is mounted, respectively. . FIG. 4 is an essential part cross-sectional view of the same place as that in FIG. 2 of the electronic device during a manufacturing step following that of FIG. 3; (A) And (b) is the principal part sectional drawing of BGA by Embodiment 1 of this invention, respectively, and the arrangement | sequence figure of the solder ball (BGA ball) supplied to the back surface of BGA. FIG. 17 is an essential part cross-sectional view of the same portion as that of FIG. 2 of the electronic device during a manufacturing step following that of FIG. 16; FIG. 19 is an essential part cross-sectional view of the same portion as that of FIG. 2 of the electronic device during a manufacturing step following that of FIG. 18; FIG. 20 is an essential part cross-sectional view of the same portion as that of FIG. 2 of the electronic device during a manufacturing step following that of FIG. 19; FIG. 21 is an essential part cross-sectional view of the same portion as that of FIG. 2 of the electronic device during a manufacturing step following that of FIG. 20; FIG. 22 is an essential part cross-sectional view of the same portion as that of FIG. 2 of the electronic device during a manufacturing step following that of FIG. 21; An example of the relationship between the height of one solder ball (conduction path) calculated using the analysis model according to the second embodiment of the present invention and the diameter of one bump land formed on the main surface of the mounting board is shown. FIG. An example of the relationship between the width of one solder ball (conduction path) calculated using the analysis model according to the second embodiment of the present invention and the diameter of one bump land formed on the main surface of the mounting board is shown. FIG. (A) And (b) is a top view of the printing mask which opposes the area | region where 1st BGA by Embodiment 2 of this invention is mounted, respectively, and the printing mask which opposes the area | region where 2nd BGA is mounted, respectively. . (A) and (b) are an arrangement diagram of a plurality of bump lands formed on the first main surface of the mounting substrate in the region where the first BGA according to the second embodiment of the present invention is mounted, and the second BGA is mounted. FIG. 6 is an array diagram of a plurality of bump lands formed on the first main surface of the mounting substrate in a region to be mounted. FIG. 5 is a schematic diagram for explaining the unfusion of the solder paste and the solder ball (BGA ball) studied by the present inventors. (A), (b), and (c) are the main parts of the BGA during solder preheating. FIG. 4 is a partial cross-sectional view, a cross-sectional view of a main part of the BGA after melting the solder, and a layout diagram of solder balls (BGA balls) supplied to the back surface of the BGA. It is principal part sectional drawing of the solder ball (BGA ball) part explaining the unfusion of the solder paste and the solder ball (BGA ball) examined by the present inventors. It is a schematic diagram explaining the bridge | bridging of the solder ball (conduction path | route) examined by the present inventors, (a), (b), and (c) are the principal part sectional drawings at the time of solder melting, respectively, It is principal part sectional drawing of the BGA after a fusion | melting, and the arrangement | positioning figure of the solder ball (BGA ball) supplied to the back surface of BGA. It is a schematic diagram explaining the ball drop of the solder ball (conduction path) examined by the present inventors, and (a), (b), and (c) are cross-sectional views of the main part of the BGA at the start of solder melting, respectively. FIG. 4 is a cross-sectional view of a main part of the BGA after the solder is melted, and a layout diagram of solder balls (BGA balls) supplied to the back surface of the BGA.

  In the following embodiments, when necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant to each other, and one is the other. There are some or all of the modifications, details, supplementary explanations, and the like.

  Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), especially when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number. Further, in the following embodiments, the constituent elements (including element steps and the like) are not necessarily indispensable unless otherwise specified and apparently essential in principle. Needless to say. Similarly, in the following embodiments, when referring to the shapes, positional relationships, etc. of the components, etc., the shapes are substantially the same unless otherwise specified, or otherwise apparent in principle. And the like are included. The same applies to the above numerical values and ranges.

  Further, in the drawings used in the following embodiments, hatching may be added to make the drawings easy to see even if they are plan views. In the following embodiments, solder balls (conduction paths) are formed on the main surface of the mounting substrate and solder balls (BGA balls) connected to a plurality of bump lands formed on the back surface of the semiconductor device. The solder paste supplied to the surfaces of the plurality of bump lands is fused and integrated, and is distinguished from the solder balls (BGA balls) supplied to the back surface of the semiconductor device.

  In all the drawings for explaining the following embodiments, components having the same function are denoted by the same reference numerals in principle, and repeated description thereof is omitted. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
An example of the mounting process of the semiconductor device according to the first embodiment will be described in the order of processes with reference to FIGS. FIG. 1 is a process diagram for explaining a mounting procedure of a semiconductor device. FIGS. 2, 3, 16, and 18 to 22 are cross-sectional views of main parts of an electronic device during the mounting process of the semiconductor device according to the first embodiment. 4 to 13 are diagrams for explaining a method for obtaining the supply amount of solder paste printed on the surfaces of a plurality of bumps and lands, and FIG. 14 is formed on the first main surface of the mounting board in the region where the BGA is mounted. FIG. 15 is a plan view of a printing mask used for printing solder paste on the plurality of bump lands formed on the first main surface of the mounting substrate, FIG. (B) is a principal part sectional view showing an example of the structure of the BGA mounted on the mounting substrate, respectively, and a layout diagram of the solder balls (BGA balls) on the back surface.

  In the first embodiment, the semiconductor device is mounted on the main surface (first main surface and second main surface) of the mounting substrate using external terminals formed on the back surface (lower surface) of the semiconductor device. Here, the external terminal in the first embodiment is made of a solder material (including lead-free solder), and the external terminal has a ball shape. Further, the ball-shaped external terminals (solder balls (BGA balls)) can be formed by a ball supply method, a printing method, a plating method, or the like. In the first embodiment, productivity and finish accuracy are good. The ball supply method was adopted. Further, in the case of the ball supply method, the amount of solder supplied to the bumps and lands can be increased as compared with the case where the printing method or the plating method is used, so that the mounting strength of the semiconductor device can be improved. Further, the ball-shaped external terminals are supplied to the back surface of the semiconductor device and are not supplied to the main surface of the mounting substrate. This is because if the ball-shaped external terminals are supplied to the main surface of the mounting substrate, troubles may occur during solder paste printing.

  In the first embodiment, an electronic device in which a plurality of semiconductor devices and other mounting components (for example, a chip capacitor) are mounted on the main surface of the mounting substrate will be described. A BGA is exemplified as the semiconductor device. The BGA has a small ball-shaped external terminal (solder ball (BGA ball)) made of a plurality of solders on its back surface, and a protective film (insulating film) formed on the ball-shaped external terminal and the main surface of the mounting substrate. The solder paste (solder paste for semiconductor device) printed on the surface of a plurality of bump lands (semiconductor device bump lands) formed so as to be exposed from the solder is fused and mounted on the mounting substrate. In addition, other mounting parts have electrodes with a plurality of solders on their side surfaces, and fuse the electrodes and solder paste printed on the surfaces of the bumps and lands formed on the main surface of the mounting board. Mounted on a mounting board.

  First, as shown in FIG. 2, the mounting substrate 1 is prepared (mounting substrate preparation step of FIG. 1).

<About mounting form>
BGA and other mounting components are soldered and mounted on the first main surface (upper surface, front surface) 1x of the mounting substrate 1 and the second main surface (lower surface, back surface) 1y located on the opposite side of the first main surface 1x. The In the first embodiment, the first BGA is mounted on the A region of the first main surface 1x of the mounting substrate 1, the second BGA is mounted on the B region of the first main surface 1x of the mounting substrate 1, and the first BGA of the mounting substrate 1 is mounted. The third BGA is mounted on the C region of the second main surface 1y, the first mounted component is mounted on the D region of the second main surface 1y of the mounting substrate 1, and the second B region is mounted on the E region of the second main surface 1y of the mounting substrate 1. Needless to say, the present invention is not limited to this.

<About the mounting board>
The mounting substrate 1 includes a base material 2, a wiring layer formed on the first main surface (surface on the first main surface 1 x side of the mounting substrate 1) 2 x of the base material 2, and the first main surface of the base material 2. And a wiring layer formed on the second main surface (surface on the second main surface 1y side of the mounting substrate 1) 2y located on the opposite side to the surface 2x. Here, the wiring layer formed on the first main surface 2x of the substrate 2 includes a plurality of wirings (other wiring patterns) formed on the wiring layer and a part of the wiring formed on the wiring layer. Bump lands (bump lands for semiconductor devices, electrode pads) 3. The bump lands 3 are exposed from a protective film (insulating film) 4 formed so as to cover the wiring layer formed on the first main surface 2x of the substrate 2. Similarly, the wiring layer formed on the second main surface 2y of the substrate 2 includes a plurality of wirings (other wiring patterns) formed on the wiring layer and a part of the wiring formed on the wiring layer. Bump lands (bump lands for semiconductor devices, electrode pads) 5. The bump lands 5 are exposed from a protective film (insulating film) 6 formed so as to cover the wiring layer formed on the second main surface 2y of the substrate 2.

  The base material 2 is formed of, for example, a highly elastic resin substrate in which a glass fiber is impregnated with an epoxy or polyimide thermosetting resin (so-called glass epoxy resin). Each wiring layer formed on the first main surface 2x and the second main surface 2y of the substrate 2 is formed of, for example, a metal film containing copper as a main component. The protective films 4 and 6 are made of, for example, a solder resist (insulating film).

  The protective films 4 and 6 are formed for the purpose of protecting each wiring layer formed on the first main surface 2x and the second main surface 2y of the substrate 2, and one of the wirings formed on the wiring layer is formed. The plurality of bump lands 3, 5 are exposed from the openings 7 formed in the protective films 4, 6 corresponding to the bump lands 3, 5. The diameter of the plurality of bump lands 3 and 5 is, for example, 0.4 mm, and the diameter of the opening formed in the protective films 4 and 6 covering the plurality of bump lands 3 and 5 is, for example, 0.5 mm. The opening 7 is provided so that the surfaces and side surfaces of the bump lands 3 and 5 are exposed from the protective films 4 and 6.

  Next, as shown in FIG. 3, a solder paste (solder paste for a semiconductor device) 8 is supplied to the surfaces of the plurality of bump lands 3 formed on the first main surface 1x of the mounting substrate 1 (the first paste in FIG. 1). 1 main surface solder paste printing process).

  For the solder paste 8, for example, lead-free solder (for example, Sn-3 [wt%] Ag-0.5 [wt%] Cu composition) substantially free of lead is used. Here, as a detailed definition of the lead-free solder, the content of lead in the solder is the one with 1.000 ppm (0.1 wt%) or less. The melting point of the lead-free solder is 217 ° C., and when the solder paste 8 is melted in the subsequent process (first reflow soldering process in FIG. 1), heat of 220 to 240 ° C. is applied to the mounting substrate 1. . For supplying the solder paste 8, for example, a solder paste printing method using a print mask 9 having openings 9 a at positions facing the plurality of bump lands 3 formed on the first main surface 1 x of the mounting substrate 1. Is used.

  Here, the solder paste 8 printed on the surface of the plurality of bump lands 3 is supplied in an amount suitable for each of the plurality of bump lands 3.

  As described above, when mounting the BGA on the mounting substrate, the solder paste and the solder ball (BGA ball) supplied to the BGA are brought into contact with each other and melted, whereby the solder paste and the solder ball (BGA ball) are brought into contact with each other. As a result, a single solder ball (conduction path) that becomes a conduction path is newly formed. However, in the step of melting the solder paste and the solder ball (BGA ball), heat of 220 to 240 ° C. is applied to the BGA, so that the BGA warps in a concave shape or a convex shape. In particular, in the first embodiment, since the lead-free solder is used for the solder paste, the heating temperature becomes higher than when a solder paste containing lead is used, and the BGA is likely to warp. Therefore, even when the BGA is warped, the solder paste and the solder ball (BGA ball) due to the warpage of the BGA are not fused, the bridge of the solder ball (conduction path), and the ball of the solder ball (conduction path) An appropriate amount of solder paste is supplied for each of a plurality of bump lands so as not to drop.

  Hereinafter, a method for obtaining the supply amount of the solder paste 8 printed on the surfaces of the plurality of bump lands 3 will be described in order from <Step 1> to <Step 6> with reference to FIGS.

  FIG. 4 is a process diagram for calculating the supply amount of the solder paste 8. 5 to 8 are diagrams for explaining a method for acquiring BGA high-temperature warpage data. FIG. 5 is a schematic diagram for explaining a high-temperature warpage measurement method for BGA. FIG. 6 shows a measurement range for high-temperature warpage of BGA. 7 is a back view of the BGA (arrangement of solder balls (BGA balls) supplied to the back surface), FIG. 7 is a graph showing the time-dependent change of the high-temperature warpage of the BGA, and FIGS. 8A and 8B are the first BGA. FIG. 9 is an arrangement diagram of a plurality of solder balls (BGA balls) arranged on the back surface of the second BGA and an arrangement diagram of the plurality of solder balls (BGA balls) arranged on the back surface of the second BGA. It is a schematic diagram which shows the shape of BGA in the room temperature before temperature rising, preheating temperature, solder melting temperature, and reflow maximum temperature. FIGS. 10A, 10B, and 10C are schematic views in which the connection portion between the mounting substrate and the BGA is represented by solder balls (conduction paths), and the connection portion between the mounting substrate and the BGA is a spring. It is the schematic diagram represented, and the schematic diagram of the solder ball (conduction path | route) explaining the parameter used for an analysis model. FIG. 11 is a graph showing an example of the relationship between the height of one solder ball (conduction path) calculated using the analysis model and the load borne by one solder ball (conduction path), and FIG. 12 shows the analysis. FIG. 13 is a graph showing an example of the relationship between the height and width of one solder ball (conduction path) when the volume of the solder ball (conduction path) calculated using the model is constant, and FIG. 13 shows solder paste and solder ball It is a schematic diagram explaining the amount of overlap with (BGA ball).

<Step 1 (high temperature warpage data in FIG. 4)>
First, high temperature warpage data of the BGA when the BGA is heated is obtained. As shown in FIG. 5, a BGA (semiconductor device) 10 that measures high-temperature warpage is installed in a heating / cooling tank 11. Thereafter, the temperature is gradually raised from room temperature to the solder melting temperature, and further gradually raised from the solder melting temperature to the maximum reflow temperature. Subsequently, the temperature is lowered from the maximum reflow temperature to the solder solidification temperature, and then gradually lowered from the solder solidification temperature to room temperature. At this time, the room temperature before the temperature rise, the solder melting temperature, the maximum reflow temperature, the solder solidification temperature, and the high temperature warpage of the BGA 10 at the room temperature after the temperature drop are measured.

  For example, as shown in FIG. 6, the measurement of the high-temperature warpage of the BGA 10 is performed in an area where the solder balls (BGA balls) 12 supplied to the back surface of the BGA 10 are attached (areas hatched in FIG. 6). The displacement of this region due to high-temperature warpage is measured by, for example, a shadow moire method using a moire image or a method using a laser displacement meter.

  In FIG. 7, an example of the result of having measured the high temperature curvature of BGA10 is shown. A state where there is no high-temperature warp is defined as “0”, a concave shape in which the central portion of the BGA 10 protrudes from the representation side toward the back surface side is “−”, and a convex shape in which the central portion of the BGA 10 protrudes from the back surface side toward the front surface side The shape is “+”. Here, the high-temperature warpage is measured for two BGAs 10 having different structures, and the respective results are shown.

  One BGA 10 is the first BGA 10a mounted in the area A of FIG. 2 described above. For example, as shown in FIG. 8A, a plurality of solder balls (BGA balls) are provided in the inner area and the outer area of the back surface of the first BGA 10a. ) 12a is arranged. Another BGA 10 is the second BGA 10b mounted in the B region of FIG. 2 described above. For example, as shown in FIG. 8B, a plurality of solder balls (BGA balls) 12b are provided only in the outer peripheral region of the back surface of the second BGA 10b. Is arranged. The size of the first BGA 10a is larger than the size of the second BGA 10b, and the size of the solder ball (BGA ball) 12a supplied to the first BGA 10a is also larger than the size of the solder ball (BGA ball) 12b supplied to the second BGA 10b.

  As shown in FIG. 7, when both the first BGA 10a and the second BGA 10b are gradually raised from room temperature, the center part once becomes a concave shape protruding in the back surface direction, but when the temperature is further raised to the maximum reflow temperature , A convex shape whose central portion protrudes in the surface direction. Next, when the temperature is lowered, the center portion becomes a concave shape protruding in the back surface direction. However, when the temperature is returned to room temperature, the first BGA 10a has a convex shape whose central portion protrudes in the front surface direction, and the second BGA 10b has a concave shape whose central portion protrudes in the back surface direction. Further, the amount of change in warpage of the first BGA 10a is larger than the amount of change in warpage of the second BGA 10b.

  For example, in the case of the BGA 10 having a convex shape whose central portion protrudes in the surface direction, such as the first BGA 10a, the solder ball (conduction path) bridge described with reference to FIG. 29 described above or the above FIG. The described solder ball (conduction path) has a poor ball drop. In addition, in the case of the BGA 10 having a concave shape with its center portion protruding in the back surface direction, such as the second BGA 10b, the solder paste and the solder ball (BGA ball) described with reference to FIGS. Poor fusion occurs.

  FIG. 9 shows another example of the result of measuring the high temperature warpage of the BGA 10. Here, detailed distribution diagrams of the high-temperature warpage of each of the first BGA 10a and the second BGA 10b are shown.

  In the case of the first BGA 10a (see FIG. 8A described above) in which the plane area is relatively large and a relatively large number of solder balls (BGA balls) 12a are supplied, the amount of warpage at room temperature is small, In a semiconductor device having a quadrangular shape, in particular, the four corners (corner portions) of the outer peripheral region are warped to the front surface side, and the central portion has a concave shape protruding in the back surface direction. If the temperature is subsequently raised to the solder melting temperature, the warpage will be gradually eased. However, if the temperature is further raised to the maximum reflow temperature, the entire outer peripheral area will be on the back side, particularly because the four corners (corners) will warp strongly on the back side. And a convex shape whose central portion protrudes in the surface direction.

  In the case of the second BGA 10b (see FIG. 8 (b) described above) in which the plane area is relatively small and the solder balls (BGA balls) 12b are supplied in a relatively small amount, the amount of warpage at room temperature is small. In a semiconductor device having a quadrangular shape, particularly, the four corners (corner portions) of the outer peripheral region warp to the surface side. However, the amount of warpage is smaller than the amount of warpage of the first BGA 10a. If the temperature is subsequently raised to the solder melting temperature, the warpage will be gradually eased. However, if the temperature is further raised to the maximum reflow temperature, the entire outer peripheral area will be on the back side, especially when the four corners (corners) warp on the back side. Warp. However, the amount of warpage is smaller than the amount of warpage of the first BGA 10a.

  In this manner, high-temperature warpage data of the BGA 10 having various package structures with different dimensions, the arrangement, the number, the size, and the like of the BGA 10 and the solder balls (BGA balls) 12 are obtained.

<Step 2 (Extraction of warpage per terminal in FIG. 4: first analysis)>
Next, the amount of high-temperature warpage of the BGA 10 at the position of each solder ball (BGA ball) 12 is extracted from the high-temperature warpage data of the BGA 10 obtained in <Step 1>. That is, by this step (analysis), the warpage amount of the BGA 10 at each position of the plurality of bump lands is measured.

<Step 3 (Solder shape in FIG. 4 -Load calibration curve calculation: second analysis)>
Next, the shape of the solder ball (conduction path) 13 is analyzed by simulation. That is, a calibration curve relating to the shape of each of the plurality of solder balls (conduction paths) 13 is calculated by this step (analysis).

  FIGS. 10A, 10B, and 10C are schematic diagrams for explaining the analysis model. FIG. 10A is a schematic diagram showing a connection portion between the mounting substrate 1 and the BGA 10 with a solder ball (conduction path) 13, and FIG. 10B shows a connection portion between the mounting substrate 1 and the BGA 10 with a spring 14. FIG. 10C is a schematic diagram of a solder ball (conduction path) 13 for explaining parameters used in the analysis model.

  The solder paste 8 printed on the surface of the plurality of bump lands 3 formed on the main surface of the mounting substrate 1 and the solder balls (BGA balls) 12 supplied to the BGA 10 are brought into contact with each other to be melted. 8 and the solder ball (BGA ball) 12 are integrated to form one new solder ball (conduction path) 13 serving as a conduction path. As shown in FIG. 10A, the molten solder ball (conduction path) 13 is deformed by external pressure, but tends to maintain its shape by surface tension. As shown in FIG. 10B, this action is considered as a spring 14, and the shape of the solder ball (conduction path) 13 is analyzed using a model in which the spring 14 supports the own weight (mg) of the BGA 10. As shown in FIG. 10C, when the force (load) a of the spring 14 is calculated, for example, the opening size (diameter D1) of the protective film 31 on the plurality of bump lands 30 formed on the back surface of the BGA 10. ), The dimensions (diameter D2) of the plurality of bump lands 3 formed on the main surface of the mounting substrate 1, the surface tension of the solder ball (conduction path) 13, the volume of the solder ball (conduction path) 13 (solder ball (conduction) (Path) width w and height h (distance between bump land 30 and bump land 3)) and the density of solder balls (conduction path) 13 are used as parameters.

  When the analysis model shown in FIG. 10 is used, the solder ball (conduction path) required to make the load a generated in each solder ball (conduction path) 13 constant when the weight of the BGA 10 is applied. A volume of 13 (height h and width w) can be obtained. Further, as shown in FIG. 13, the shape of the solder ball (conduction path) 13 can be calculated using the overlap amount of the solder paste 8 and the solder ball (BGA ball) 12 as an index.

  FIG. 11 and FIG. 12 show an example of a simulation result such as the shape of the solder ball (conduction path) 13 obtained by using the analysis model described above. In this simulation, in addition to the parameters related to one solder ball (conduction path) 13 shown in FIG. 10C, data related to the BGA 10 (for example, the dimensions of the BGA 10, the arrangement of the solder balls (BGA balls) 12, the solder The number of balls (BGA balls) 12, the dimensions of the bump lands 30 and the like, the data relating to the mounting substrate 1 (for example, the dimensions of the mounting substrate 1 and the dimensions of the bump lands 3), and the data relating to the printing mask 9 (eg the opening 9a). And the supply amount of the solder paste 8 are used.

FIG. 11 shows an example of the relationship between the height h of one solder ball (conduction path) 13 calculated using the analysis model described above and the load a borne by one solder ball (conduction path) 13. FIG. 12 and FIG. 12 are graphs showing an example of the relationship between the height h and the width w of one solder ball (conduction path) 13 when the volume of the solder ball (conduction path) 13 is constant. Here, the dimension D1 of the plurality of bump lands 30 formed on the back surface of the BGA 10 is constant, and the dimension D2 of the plurality of bump lands 3 formed on the main surface of the mounting substrate 1 is also constant. Further, the solder ball (conduction path) 13 has a volume of 0.68 × 10 ⁻¹² m ³ (first solder ball; φ0.5 mm + volume assuming a solder paste) and 0.36 × 10 ⁻¹² m ³ ( The shape of the solder ball is analyzed in the case of the second solder ball (volume assuming φ0.4 mm + solder paste).

<Step 4 (Calculation of single solder shape in FIG. 4)>
Simultaneously with the above <Step 3>, the shape of the solder ball (BGA ball) 12 formed on the BGA 10 is calculated by simulation. The solder ball (BGA ball) 12 is analyzed using the same method as the method for analyzing the solder ball (conduction path) 13 (see FIGS. 10A to 10C). In the process of calculating the shape, the solder paste 8 is not used. Thus, by calculating the shape change of the solder ball (BGA ball) 12 in a state where the amount of solder is small, the amount of solder paste 8 to be supplied can be calculated more accurately.

<Step 5 (Calculation of solder shape when mounted in FIG. 4)>
Next, the amount of high-temperature warpage of the BGA 10 at the position of each solder ball (BGA ball) 12 obtained in <Step 2>, and the shape and load of the solder ball (conduction path) 13 obtained in <Step 3> From the calibration curve, the shape of the solder ball (conduction path) 13 is calculated.

  For example, the unfused defect between the solder paste 8 and the solder ball (BGA ball) 12 due to the warpage of the BGA 10 (see FIG. 27) and the ball drop of the solder ball (conduction path) 13 (see FIG. 30) are prevented. Therefore, the first solder paste amount with a large supply amount of the solder paste 8 is used. In this case, as shown in FIGS. 11 and 12, for example, the height h of the solder ball (conduction path) 13 formed by applying a load a of 0.05 gf is about 0.270 mm, and the width w is about 0.2 mm. The height h of the solder ball (conduction path) 13 formed by applying a load a of 0.2 gf is about 0.16 mm and the width w is about 0.77 mm.

  However, when the solder ball (conduction path) 13 is crushed and widened, the bridge of the solder ball (conduction path) 13 (see FIG. 29 described above) becomes a problem. Therefore, at a place where a load a of 0.2 gf is applied, the supply amount of the solder paste 8 is reduced to the second solder paste amount, and the width w of the solder ball (conduction path) 13 is reduced. By using the second solder paste amount, the height h of the solder ball (conduction path) 13 formed by applying a load a of 0.2 gf is about 0.16 mm and the width w is about 0.58 mm.

  Thus, the supply amount of the solder paste 8 printed on the surface of each bump land 3 formed on the main surface of the mounting substrate 1 can be calculated by simulation.

<Step 6 (Output of the result of FIG. 4)>
Next, after the calculation is completed, the supply amount of the solder pace 8 printed at the position corresponding to each solder ball (BGA ball) 12 is output, and the thickness of the print mask 9 and the opening 9a are opened. Output the caliber, etc. Further, data and shape of each solder ball (conduction path) 13 are output.

  An appropriate amount of solder paste 8 obtained by the analysis method shown in the above <Step 1> to <Step 6> is supplied to each of the plurality of bump lands 3.

  In the first embodiment, in order to change the supply amount of the solder paste 8 for each of the plurality of bump lands 3 formed on the first main surface 1 x of the mounting substrate 1, a plurality of openings formed in the printing mask 9. The opening diameter of 9a was changed.

  FIGS. 14A and 14B are an arrangement diagram of a plurality of bump lands 3 formed on the first main surface 1x of the mounting substrate 1 in a region (A region) where the first BGA 10a is mounted and a second BGA 10b, respectively. The arrangement | sequence diagram of the several bump land 3 formed in the 1st main surface 1x of the mounting board | substrate 1 of the area | region (B area | region) to be mounted is shown.

  As shown in FIG. 14A, the A region of the first main surface 1x of the mounting substrate 1 faces a plurality of solder balls (BGA balls) 12a supplied to the first BGA 10a mounted in the A region. As described above, the plurality of bump lands 3 are arranged in consideration of the pitch and dimensions of the plurality of solder balls (BGA balls) 12a. The dimensions of the plurality of bump lands 3 in the area A are all constant. Similarly, as shown in FIG. 14B, a plurality of solder balls (BGA balls) 12b supplied to the second BGA 10b mounted in the B region are provided in the B region of the first main surface 1x of the mounting substrate 1. A plurality of bump lands 3 are arranged in consideration of the pitch and dimensions of the plurality of solder balls (BGA balls) 12b. The dimensions of the plurality of bump lands 3 in the area B are all constant. The surfaces and side surfaces of the plurality of bump lands 3 are exposed from the openings 7 provided in the protective film 4 covering the first main surface 1x of the mounting substrate 1.

  However, as described above with reference to FIGS. 7 to 9, the shape of the first BGA 10a when the temperature is returned to room temperature after the reflow process is a convex shape whose central portion protrudes in the surface direction, and the second BGA 10b The shape is a concave shape whose central portion protrudes in the back surface direction. Therefore, in the first BGA 10a, the supply amount of the solder paste 8 printed on the bump lands 3 located at the center of the A region of the mounting substrate 1 is increased, and the outer periphery of the A region in which the planar shape of the mounting substrate 1 is a quadrangle. It is necessary to reduce the supply amount of the solder paste 8 printed on the bump land 3 located in the region (especially at the four corners (corner portions)). On the other hand, in the second BGA 10b, the supply amount of the solder paste 8 printed on the bump land 3 located at the center of the B region having a square shape on the mounting substrate 1 is reduced, and the B of the mounting substrate 1 is reduced. It is necessary to increase the supply amount of the solder paste 8 printed on the bump lands 3 located in the outer peripheral region (particularly, the four corners (corner portions)) of the region.

  FIG. 15 shows a plan view of an example of a print mask 9 used when the solder paste 8 is printed on the surfaces of the plurality of bump lands 3 formed on the first main surface 1x of the mounting substrate 1. FIG. 15A is a plan view of the print mask 9 facing the A area where the first BGA 10a is mounted, and FIG. 15B is a plan view of the print mask 9 facing the B area where the second BGA 10b is mounted. is there.

  Since the shape of the first BGA 10a when it is returned to room temperature after performing the reflow process becomes a convex shape that protrudes its central portion in the surface direction, the bridge of the solder ball (conduction path) 13 and the solder ball (conduction path) 13 There is concern about falling balls. Therefore, as shown in FIG. 15A, an opening 9a having a first opening diameter having a relatively large diameter is formed in the print mask 9 facing the center of the area A of the mounting substrate 1. The supply amount of the solder paste 8 is increased. On the other hand, the print mask 9 facing the four corners (corner portions) of the A region of the mounting substrate 1 has an opening having a second opening diameter that is relatively small (smaller than the first opening diameter). The portion 9a is formed to reduce the supply amount of the solder paste 8. And the printing mask 9 which opposes area | regions other than the center part and four corners (corner part) of the A area | region of the mounting substrate 1 has a 3rd opening diameter smaller than a 1st opening diameter and larger than a 2nd opening diameter. Opening 9a is formed.

  In this way, by changing the opening diameter of the opening 9a of the printing mask 9, a large amount of solder paste 8 is supplied to the center of the region A of the mounting substrate 1, and a small amount of solder paste 8 is supplied to the four corners (corners). . Thereby, solder balls (conduction paths) 13 having a small volume can be formed at the four corners (corners) of the area A of the mounting substrate 1 by a subsequent reflow process. Can be prevented. Further, a large amount of solder is supplied to the central portion of the A region of the mounting substrate 1, and the connection between the bump land 30 formed on the back surface of the first BGA 10a and the solder ball (BGA ball) 12a by the subsequent reflow process. Since the portion is reinforced, it is possible to prevent the solder balls (conduction paths) 13 from falling off.

  On the other hand, the second BGA 10b has a concave shape in which the central portion protrudes in the back surface direction after returning to room temperature after the reflow treatment, so that the solder paste 8 and the solder ball (BGA ball) 12 are not fused. Is concerned. Therefore, as shown in FIG. 15B, the printing mask 9 facing the four corners (corner portions) of the B region of the mounting substrate 1 is formed with an opening portion 9a having a relatively large fourth opening diameter. Thus, the supply amount of the solder paste 8 is increased. An opening 9 a having a fifth opening diameter smaller than the fourth opening diameter is formed in the print mask 9 that faces areas other than the four corners (corners) of the outer peripheral area of the mounting substrate 1.

  In this way, by changing the opening diameter of the opening 9 a of the printing mask 9, a large amount of solder paste 8 is supplied to the four corners (corners) of the B region of the mounting substrate 1. As a result, the solder balls 8 and the solder balls (BGA balls) can be formed at the four corners (corner portions) of the B region of the mounting substrate 1 by the subsequent reflow process. ) Unfused with 12 can be prevented.

  In the printing mask 9 facing the region A of the mounting substrate 1 shown in FIG. 15A, three types of openings (first opening diameter, second opening diameter, and third opening diameter) having different opening diameters are formed. In the printing mask 9 facing the region B of the mounting substrate 1 shown in FIG. 15B, two types of openings (fourth opening diameter and fifth opening diameter) having different opening diameters were formed. Needless to say, the present invention is not limited to this. For example, the print mask 9 facing the A region of the mounting substrate 1 forms four or more types of openings having different opening diameters, and the printing mask 9 facing the B region of the mounting substrate 1 has 3 different opening diameters. More than one type of opening can be formed.

  Next, as shown in FIG. 16, the first BGA 10a and the second BGA 10b are mounted on the first main surface 1x of the mounting substrate 1 (BGA mounting step in FIG. 1).

  More specifically, a plurality of bump lands 3 formed in the A region and a plurality of solder balls (BGA balls) 12a supplied to the first BGA 10a are opposed to the A region of the first main surface 1x of the mounting substrate 1. As described above, the first BGA 10a is disposed via the solder paste 8 formed on the surfaces of the plurality of bump lands 3. Similarly, a plurality of bump lands 3 formed in the B region and a plurality of solder balls (BGA balls) 12b supplied to the second BGA 10b are opposed to the B region of the first main surface 1x of the mounting substrate 1. In addition, the second BGA 10b is disposed via the solder paste 8 formed on the surfaces of the plurality of bump lands 3.

  FIG. 17 shows an example of the structure of the BGA 10 mounted on the mounting substrate 1 according to the first embodiment. FIGS. 17A and 17B are a cross-sectional view of the main part of the BGA 10 and an array of the solder balls (BGA balls) 12 supplied to the back surface of the BGA 10, respectively.

  The BGA 10 in the present embodiment is made of a glass epoxy resin and has an upper surface (front surface) 15x, a lower surface (back surface) 15y opposite to the upper surface 15x, and a plurality of bump lands ( A wiring board 15 having an electrode pad) 21, a main surface (front surface) made of silicon, a back surface opposite to the main surface, and a semiconductor element formed on the main surface; A semiconductor chip 16 mounted on the upper surface 15x, a resin sealing body (sealing body) 25 made of an epoxy resin and sealing the semiconductor chip 16, and a plurality of bumps formed on the lower surface 15y of the wiring substrate 15 The package structure includes a plurality of solder balls (BGA balls) 12 formed on each of the lands 21. The planar shape of each of the upper surface 15x and the lower surface 15y of the wiring board 15 is a quadrangle.

<Semiconductor chip>
The semiconductor chip 16 mounted on the upper surface of the wiring board 15 via an adhesive (die bonding material) 17 has a quadrangular planar shape intersecting the thickness direction. In addition, although the adhesive 17 used in this Embodiment 1 is a paste-form adhesive, it is not limited to this, You may use a film-form adhesive.

  The semiconductor chip 16 is not limited to this, but mainly includes a semiconductor substrate and a plurality of semiconductor elements (an internal circuit including a core power supply circuit, an input / output circuit) formed on the main surface (front surface) of the semiconductor substrate. And a multilayer wiring layer in which a plurality of insulating layers and wiring layers are stacked on the main surface of the semiconductor substrate, and a surface protection film formed so as to cover the multilayer wiring layer. The insulating layer is made of, for example, a silicon oxide film. The wiring layer is formed of a metal film such as aluminum, tungsten, or copper. The surface protective film is formed of a multilayer film in which an inorganic insulating film and an organic insulating film such as a silicon oxide film or a silicon nitride film are stacked.

  On the main surface of the semiconductor chip 16, a plurality of electrode pads 18 electrically connected to the semiconductor elements described above are arranged along each side of the semiconductor chip 16 (FIG. 17A shows a plurality of electrode pads 18. A part of the electrode pad 18 is described). These electrode pads 18 are composed of the uppermost wiring of the multilayer wiring layers of the semiconductor chip 16 and are exposed through openings formed in the surface protective film of the semiconductor chip 16 corresponding to the respective electrode pads 18. .

<Wiring board>
The wiring board 15 has a quadrangular planar shape that intersects the thickness direction. Although not limited to this, the wiring board 15 has a multilayer wiring structure and has four wiring layers in the first embodiment. More specifically, the wiring board 15 is formed so as to cover the core material, the wiring layer formed on the surface of the core material (second wiring layer from the top in the wiring board 15), and the wiring layer. It has an insulating layer and a wiring layer (the uppermost wiring layer in the wiring board 15) formed on the surface of the insulating layer. Here, the plurality of bonding leads (electrode pads) 19 are formed of a part of the wiring formed in the uppermost wiring layer, and are exposed from the protective film 20 formed so as to cover the uppermost wiring layer. ing. Further, the wiring board 15 is formed so as to cover the wiring layer (third wiring layer from the top in the wiring board 15) formed on the back surface located on the opposite side to the front surface of the core material. It has an insulating layer and a wiring layer (the lowermost wiring layer in the wiring board 15) formed on the surface of the insulating layer. Here, the plurality of bump lands (electrode pads) 21 are formed of a part of the wiring formed in the lowermost wiring layer, and are exposed from the protective film 22 formed so as to cover the lowermost wiring layer. is doing.

  In addition, the wiring substrate 15 has a conductive member (inner wall) in each of the through holes (vias) 23 formed from the upper surface 15x to the lower surface 15y of the wiring substrate 15 or from the front surface to the back surface of the core material. Wiring). Each insulating layer of the core material is formed of, for example, a highly elastic resin substrate in which a glass fiber is impregnated with an epoxy or polyimide thermosetting resin. Each wiring layer of the wiring board 15 is formed of, for example, a metal film containing copper as a main component. The protective film 20 on the surface of the wiring board 15 is formed mainly for the purpose of protecting the wiring formed on the uppermost layer of the wiring board 15, and the protective film 22 on the back surface of the wiring board 15 is mainly used for the wiring board 15. It is formed for the purpose of protecting the wiring formed in the lowermost layer.

  The plurality of uppermost layer wirings and the plurality of lowermost layer wirings formed on the wiring board 15 are electrically connected to each other by conductive members (wirings) formed inside the plurality of through holes 23 penetrating the core material. ing.

<Wire>
A plurality of electrode pads 18 arranged on the main surface of the semiconductor chip 16 and a plurality of bonding leads 19 arranged on the upper surface 15x of the wiring substrate 15 are a plurality of conductive members (wires in the first embodiment). 24 are electrically connected to each other (a part of the plurality of conductive members 24 is shown in FIG. 17A). For example, a gold wire is used for the conductive member 24. The conductive member 24 is disposed on the electrode pad 18 disposed on the main surface of the semiconductor chip 16 and the upper surface 15x of the wiring substrate 15 by, for example, a nail head bonding (ball bonding) method using ultrasonic vibration in combination with thermocompression bonding. It is connected to the bonding lead 19.

  The semiconductor chip 16 and the conductive member 24 are sealed by a resin sealing body (sealing body) 25 formed on the upper surface 15x of the wiring board 15. The resin sealing body 25 is formed of an epoxy-based thermosetting insulating resin to which, for example, a phenol-based curing agent, silicone rubber, and a large number of fillers (for example, silica) are added, for the purpose of reducing stress. The resin sealing body 25 is formed by, for example, a transfer mold method.

<External terminal (BGA ball)>
A plurality of solder balls (BGA balls) 12 are formed on the plurality of bump lands 21 formed on the lower surface 15 y of the wiring board 15. As described above, the plurality of bump lands 21 are exposed in the protective film 22 on the lower surface 15y of the wiring board 15 through the openings formed corresponding to the respective bump lands 21, and the plurality of solder balls The (BGA ball) 12 is electrically and mechanically connected to the plurality of bump lands 21. As the solder ball (BGA ball) 12, a solder bump having a lead-free solder composition that does not substantially contain lead, for example, a solder bump having a Sn-3 [wt%] Ag-0.5 [wt%] Cu composition is used. .

  Next, as shown in FIG. 18, a reflow process is performed on the mounting substrate 1 on which the first BGA 10a and the second BGA 10b are mounted (first reflow soldering step in FIG. 1).

  The temperature of the reflow process is, for example, 220 to 240 ° C. By this reflow process, the solder balls (BGA balls) 12a supplied to the first BGA 10a and the solder paste 8 printed on the surfaces of the plurality of bump lands 3 formed in the area A of the mounting substrate 1 are melted and integrated. Thus, a new solder ball (conduction path) 13 is formed so as to cover the surface and side surface of the bump land 3. The newly formed solder ball (conduction path) 13 becomes a conduction path for inputting and outputting electrical signals between the BGA 10 and the mounting substrate 1. When a plurality of solder balls (BGA balls) 12a are mounted on the first BGA 10a, the balls are respectively applied to the plurality of bump lands 30 formed on the back surface of the first BGA 10a via a solder paste (solder paste for solder balls). Solder balls (BGA balls) 12 are formed by connecting the shaped electrodes. Therefore, the solder ball (conduction path) 13 includes the solder paste used when the plurality of solder balls (BGA balls) 12a are mounted on the first BGA 10a.

  At the same time, the solder balls (BGA balls) 12b supplied to the second BGA 10b and the solder paste 8 printed on the surfaces of the plurality of bump lands 3 formed in the B region of the mounting substrate 1 are melted and integrated, Solder balls (conduction paths) 13 are formed so as to cover the surface and side surfaces of the bump land 3. Similar to the first BGA 10a described above, the solder ball (conduction path) 13 also includes a solder paste used when a plurality of solder balls (BGA balls) 12b are mounted on the second BGA 10b.

  At this time, as described above, the first BGA 10a has a convex shape that protrudes its central portion in the surface direction, so there is a concern about the bridge of the solder balls (conduction paths) 13. However, since a large amount of solder paste 8 is supplied to the center of the A region of the mounting substrate 1 and a small amount of solder paste 8 is supplied to the four corners (corner portions) of the outer peripheral region, the A region of the mounting substrate 1 is obtained by reflow processing. A solder ball (conduction path) 13 having a large volume is formed at the center of the substrate, and solder balls (conduction paths) 13 having a small volume are formed at the four corners (corner portions) of the area A of the mounting substrate 1. Thereby, the bridge of the solder ball (conduction path) 13 in the outer peripheral region of the first BGA 10a can be prevented.

  Further, as described above, since the second BGA 10b has a concave shape that protrudes its central portion in the back surface direction, there is a concern that the solder paste 8 and the solder balls (BGA balls) 12b are not fused. However, since a large amount of solder paste 8 is supplied to the four corners (corner portions) of the outer peripheral region of the B region of the mounting substrate 1, a large volume is provided to the four corners (corner portions) of the B region of the mounting substrate 1 by reflow processing. Solder balls (conduction paths) 13 are formed. Thereby, unfusion of the solder paste 8 and the solder ball (BGA ball) 12b in the outer peripheral region of the second BGA 10b can be prevented.

  Next, as shown in FIG. 19, the mounting substrate 1 is reversed (mounting substrate reversing step of FIG. 1).

  Next, as shown in FIG. 20, a solder paste (solder paste for a semiconductor device) 26 is supplied to the surfaces of the plurality of bump lands 5 formed on the second main surface (lower surface, back surface) 1y of the mounting substrate 1. (Second main surface solder paste printing step in FIG. 1).

  Similar to the first main surface 1x side of the mounting substrate 1, the solder paste 26 includes, for example, lead-free solder substantially free of lead (for example, Sn-3 [wt%] Ag-0.5 [wt%] Cu Composition). The melting point of the lead-free solder is 217 ° C., and when the solder paste 26 is melted in the subsequent step (second reflow soldering step in FIG. 1), heat of 220 to 240 ° C. is applied to the mounting substrate. For supplying the solder paste 26, for example, a solder paste printing method using a printing mask 27 having openings 27a at positions facing the plurality of bump lands 5 formed on the second main surface 1y of the mounting substrate 1. Is used.

  Here, in the same manner as the first main surface solder paste printing step described above (the step described with reference to FIGS. 3 to 15), the solder paste 26 supplied to the surfaces of the plurality of bump lands 5 is a plurality of bumps. -A suitable amount for each land 5 is supplied. The method for determining an appropriate amount of the solder paste 26 to be supplied to each bump land 5 and the method for supplying the solder paste 26 are the same as those in the first main surface solder paste printing step described above. Detailed description is omitted.

  For example, the third BGA 10c is mounted on the C region of the second main surface 1y of the mounting substrate 1, and when the third BGA 10c is a BGA having the same structure as the second BGA 10b described above, for example, a reflow process was performed. After that, the shape when the temperature is returned to room temperature becomes a concave shape whose central portion protrudes in the back surface direction. In this case, there is a concern that the solder paste 26 and the solder ball (BGA ball) 12c are not fused. Therefore, as shown in FIG. 15B described above, the print mask 27 facing the four corners (corner portions) of the outer peripheral region of the C region having a square shape on the mounting substrate 1 has a relatively large diameter. The opening 27a having the fourth opening diameter is formed to increase the supply amount of the solder paste 26. An opening 27 a having a fifth opening diameter smaller than the fourth opening diameter is formed in the printing mask 27 facing the region other than the four corners (corner portions) of the mounting substrate 1.

  In this way, by changing the opening diameter of the opening 27a of the printing mask 27, a large amount of solder paste 26 is supplied from the C region of the mounting substrate 1 to the four corners (corner portions) of the outer peripheral region. As a result, solder balls (conduction paths) 13 having a large volume can be formed at the four corners (corner portions) of the C region of the mounting substrate 1 by the subsequent reflow process. Therefore, the solder paste 26 and the solder balls (BGA balls) ) Unfusion with 12c can be prevented.

  Next, as shown in FIG. 21, the third BGA 10c, the first mounting component 10d, and the second mounting component 10e are mounted on the second main surface 1y of the mounting substrate 1 (BGA and component mounting step in FIG. 1).

  More specifically, the solder paste 26 and the third BGA 10c are formed (supplied and printed) on the surfaces of the plurality of bump lands 5 formed in the C region in the C region of the second main surface 1y of the mounting substrate 1. The third BGA 10c is mounted so that the supplied solder balls (BGA balls) 12c face each other. At the same time, the solder paste 26 printed on the surface of the plurality of bump lands 5 formed in the D region and the electrode formed on the side surface of the first mounting component 10d on the D region of the second main surface 1y of the mounting substrate 1 The first mounting component 10d is mounted so as to be in contact with 12d. At the same time, the solder paste 26 printed on the surface of the plurality of bump lands 5 formed in the E region and the side surface of the second mounting component 10e are formed in the E region of the second main surface 1y of the mounting substrate 1. The second mounting component 10e is mounted so as to be in contact with the electrode 12e.

  Next, as shown in FIG. 22, a reflow process is performed on the mounting substrate 1 on which the third BGA 10c, the first mounting component 10d, and the second mounting component 10e are mounted (second reflow soldering step in FIG. 1).

  The temperature of the reflow process is, for example, 220 to 240 ° C. By this reflow process, the solder balls (BGA balls) 12c supplied to the third BGA 10c and the solder paste 26 printed on the surfaces of the plurality of bump lands 5 formed in the region C of the mounting substrate 1 are melted and integrated. Thus, solder balls (conduction paths) 13 are formed so as to cover the surface and side surfaces of the bump lands 5. Similar to the first BGA 10a and the second BGA 10b described above, the solder ball (conduction path) 13 includes a solder paste used when a plurality of solder balls (BGA balls) 12c are mounted on the third BGA 10c. .

  At the same time, the electrode 12d of the first mounting component 10d and the solder paste 26 printed on the surfaces of the plurality of bump lands 5 formed in the D region of the mounting substrate 1 are melted and integrated. At the same time, the electrode 12e of the second mounting component 10e and the solder paste 26 printed on the surfaces of the plurality of bump lands 5 formed in the E region of the mounting substrate 1 are melted and integrated.

  At this time, since the third BGA 10c has a concave shape that protrudes the central portion in the back surface direction, there is a concern that the solder paste 26 and the solder balls (BGA balls) 12c are not fused. However, since a large amount of solder paste 26 is supplied to the four corners (corner portions) of the outer peripheral region of the C region of the mounting substrate 1, the volume is large at the four corners (corner portions) of the C region of the mounting substrate 1 by reflow processing. Solder balls (conduction paths) 13 are formed. Thereby, unfusion of the solder paste 26 and the solder ball (BGA ball) 12c in the outer peripheral region of the third BGA 10c can be prevented.

  At this time, the solder balls located between the plurality of bump lands 30 formed on the back surface of the first BGA 10a and the plurality of bump lands 3 formed in the area A of the first main surface 1x of the mounting substrate 1 (Conduction path) 13 and a plurality of bump lands 30 formed on the back surface of the second BGA 10b and a plurality of bump lands 3 formed in a B region of the first main surface 1x of the mounting substrate 1 The solder balls (conduction paths) 13 are also melted.

  However, as described above, since the first BGA 10a supplies a large amount of solder paste 8 to the center of the A region of the mounting substrate 1, a large volume solder ball (BGA ball) 12 is formed there. Further, it is possible to prevent the balls of the solder balls (conduction paths) 13 from dropping. Further, since the first BGA 10a supplies a small amount of solder paste 8 to the four corners (corner portions) of the outer peripheral area of the area A of the mounting substrate 1, solder balls (conduction paths) 13 having a small volume are formed there. Thus, bridging of the solder balls (conduction paths) 13 can be prevented. In addition, since the second BGA 10b supplies a small amount of solder paste 8 to the four corners (corner portions) of the outer peripheral region of the B region of the mounting substrate 1, solder balls (conduction paths) 13 having a small volume are formed there. Thus, bridging of the solder balls (conduction paths) 13 can be prevented.

  As described above, the first BGA 10a is mounted in the A region of the first main surface 1x of the mounting substrate 1 and the second BGA 10b is mounted in the B region by the steps described above. Further, the third BGA 10c is mounted on the C region of the second main surface 1y of the mounting substrate 1, the first mounting component 10d is mounted on the D region, and the second mounting component 10e is mounted on the E region. This substantially completes the electronic device.

  In the first embodiment, the mounting substrate 1 is used as a method of setting the volume of the plurality of solder balls (conduction paths) 13 to a volume required at each solder ball (conduction path) 13 placement. Method of Printing Solder Pastes 8 and 26 in Supply Amount Suitable for Individual Bump Lands 3 and 5 on the Surfaces of the Bump Lands 3 and 5 Formed on the First Main Surface 1x or the Second Main Surface 1y Was used. However, it is not limited to this method.

  For example, as a method of setting the volume of the plurality of solder balls (conduction paths) 13 to a volume required at the place where each solder ball (conduction path) 13 is disposed, the back surface of the first BGA 10a, the second BGA 10b, or the third BGA 10c is used. A method of printing a suitable amount of solder paste on the surface of the plurality of bump lands 30 formed may be used. That is, when solder balls (BGA balls) 12a, 12b, 12c are formed on the back surface of the first BGA 10a, the second BGA 10b, or the third BGA 10c, a solder paste is printed on the surface of the plurality of bump lands 30, After supplying the ball-shaped electrodes to the surfaces of the lands 30, reflow treatment is performed. Therefore, an appropriate amount of solder paste is printed for each of the plurality of bump lands 30 to form solder balls (BGA balls) 12a, 12b, and 12c having a necessary volume in advance. The solder balls (BGA balls) 12a, 12b, and 12c and the solder printed on the surfaces of the plurality of bump lands 3 and 5 formed on the first main surface 1x or the second main surface 1y of the mounting substrate 1. By melting the pastes 8 and 26, it is possible to form solder balls (conduction paths) 13 having a shape suitable for the place of arrangement. In this case, the amounts of the solder pastes 8 and 26 supplied to the surfaces of the plurality of bump lands 3 and 5 formed on the first main surface 1x or the second main surface 1y of the mounting substrate 1 are all the same. Also good.

  Thus, according to the first embodiment, the plurality of bump lands 30 formed on the back surface of the BGA 10 (for example, the first BGA 10a, the second BGA 10b, and the third BGA 10c) and the first main surface 1x or the second of the mounting substrate 1 are provided. The volume of the plurality of solder balls (conduction paths) 13 connecting the plurality of bump lands 3 and 5 formed on the main surface 1y is required at the place where each solder ball (conduction path) 13 is disposed. By setting the volume to a predetermined level, defects that occur when the BGA 10 is mounted on the first main surface 1x or the second main surface 1y of the mounting substrate 1 (unfused solder paste and solder balls (BGA balls), solder balls (conduction) Path) and solder balls (conduction paths) can be prevented from falling.

  Specifically, the deformation (warpage amount and warpage shape) of the BGA 10 mounted on the first main surface 1x or the second main surface 1y of the mounting substrate 1 is analyzed, and a plurality of bumps formed on the back surface of the BGA 10 Calculation of the shape of each solder ball (conduction path) 13 that connects the land 30 and the plurality of bump lands 3, 5 formed on the first main surface 1 x or the second main surface 1 y of the mounting substrate 1. Thus, the supply amount of the solder pastes 8 and 26 suitable for the individual bump lands 3 and 5 is obtained. Then, the opening diameters of the openings 9a and 27a of the printing masks 9 and 27 used when supplying the solder pastes 8 and 26 are changed according to the volume of each solder ball (conduction path) 13 to be necessary. The solder pastes 8 and 26 are printed on the surfaces of the plurality of bump lands 3 and 5 formed on the first main surface 1x or the second main surface 1y of the mounting substrate 1. Thereafter, a reflow process is performed on the mounting substrate 1 on which the BGA 10 is mounted, thereby forming solder balls (conducting paths) 13 having a volume necessary for the locations where the plurality of solder balls (conducting paths) 13 are respectively arranged.

  By preventing the above problems, the mounting yield of the BGA 10 can be improved.

(Embodiment 2)
In the first embodiment described above, the opening diameters of the openings 9a of the printing masks 9 and 27 used when supplying the solder pastes 8 and 26 are changed according to the volume of each solder ball (conduction path) 13. The required amount of solder paste 8, 26 is printed on the surface of each of the plurality of bump lands 3, 5 formed on the first main surface 1x or the second main surface 1y of the mounting substrate 1, thereby arranging the locations. A solder ball (conduction path) 13 having a shape suitable for the above was formed.

  In the second embodiment, unlike the first embodiment, the dimensions (diameters) of the plurality of bump lands 3 and 5 formed on the first main surface 1x or the second main surface 1y of the mounting substrate 1 are changed. As a result, a solder ball (conduction path) 13 having a shape suitable for the placement location is formed.

  Since the mounting process of the semiconductor device and the analysis method of the shape of the solder ball (conduction path) 13 according to the second embodiment are the same as those in the first embodiment, the description thereof is omitted here. In the second embodiment, a solder ball (on the surface of the plurality of bump lands 3 formed on the first main surface 1x of the mounting substrate 1 is changed by changing the dimensions of the bump lands 3). A method for forming the conduction path 13 will be described. On the surface of the plurality of bump lands 5 formed on the second main surface 1y of the mounting substrate 1, solder balls (conduction paths) 13 suitable for the placement location are formed by changing the dimensions of the bump lands 5. The method is the same.

  First, the analysis method shown in <Step 1> to <Step 6> of the shape of the solder ball (conduction path) 13 according to the first embodiment described above (using FIGS. 4 to 10 in the first embodiment described above). The diameter of each of the plurality of bump lands 3 formed on the first main surface 1x of the mounting substrate 1 is calculated using the above-described method for calculating the supply amount of the solder paste 8).

Specifically, in <Step 5> described above, calculation results regarding the diameters of the plurality of bump lands 3 formed on the first main surface 1x of the mounting substrate 1 shown in FIGS. 23 and 24, for example, are obtained by simulation. . FIG. 23 shows an example of the relationship between the height of one solder ball (conduction path) 13 calculated using the analysis model and the diameter of one bump land 3 formed on the first main surface 1x of the mounting substrate 1. FIG. 24 is a graph showing the width of one solder ball (conduction path) 13 calculated using the analysis model and the diameter of one bump land 3 formed on the first main surface 1x of the mounting substrate 1. It is a graph which shows an example of a relationship. 23 and 24, the dimensions of the plurality of bump lands 30 formed on the back surface of the BGA 10 are constant. Further, the solder ball (conduction path) 13 has a volume of 0.68 × 10 ⁻¹² m ³ (first solder ball; φ0.5 mm + volume assuming a solder paste) and 0.36 × 10 ⁻¹² m ³ ( The shape of the solder ball (conduction path) 13 is analyzed for the case of the second solder ball (φ0.4 mm + volume assuming solder paste).

  As shown in FIG. 23, even when the same amount of solder paste 8 is supplied, the solder balls formed by melting the solder paste 8 and the solder balls (BGA balls) 12 due to the different diameters of the bump lands 3. The height of the (conduction path) 13 is different, and the height of the solder ball (conduction path) 13 decreases as the diameter of the bump land 3 increases. On the other hand, as shown in FIG. 24, even when the same amount of solder paste 8 is supplied, the bump lands 3 have different diameters, so that the solder paste 8 and the solder balls (BGA balls) 12 melt. The width of the solder ball (conduction path) 13 to be formed is different, and the width of the solder ball (conduction path) 13 increases as the diameter of the bump land 3 increases. When the diameter of the bump / land 3 is small, the diameter of the solder ball (conduction path) 13 is larger than the diameter of the bump / land 3, but when the diameter of the bump / land 3 is large, the solder ball (conduction) The diameter of the (path) 13 is the same as or smaller than the diameter of the bump land 3, and the solder ball (conduction path) 13 does not protrude from the bump land 3. For example, if the bump land 3 is 0.2 mm in the second solder paste amount, the diameter of the solder ball (conduction path) 13 is about 0.475 mm, but the bump land 3 is 0.5 mm. The diameter of the solder ball (BGA ball) 12 is about 0.5 mm.

  Therefore, the unfused defect between the solder paste 8 and the solder ball (BGA ball) 12 due to the warpage of the BGA 10 (see FIG. 27) and the ball drop of the solder ball (conduction path) 13 (see FIG. 30) are prevented. A bump land 3 having a relatively small diameter is provided on the first main surface 1x of the mounting substrate 1 in order to form a high solder ball (conduction path) 13 in the region that needs to be formed. However, if the diameter of the bump land 3 is small, the diameter of the solder ball (conduction path) 13 is larger than the diameter of the bump land 3 and the bridge of the solder ball (conduction path) 13 (see FIG. 29 described above). Since it is easy to occur, a bump land 3 having a relatively large diameter is provided on the first main surface 1x of the mounting substrate 1 in a region where it is necessary to prevent the solder ball (conduction path) 13 from bridging.

  In this manner, the respective diameters of the plurality of bump lands 3 formed on the first main surface 1x of the mounting substrate 1 can be calculated by simulation.

  Next, an appropriate amount of solder paste 8 is supplied for each of the plurality of bump lands 3. In the second embodiment, the solder paste 8 is formed on the first main surface 1x of the mounting substrate 1 in order to change the supply amount of the solder paste 8 for each of the plurality of bump lands 3 formed on the first main surface 1x of the mounting substrate 1. The dimensions of the plurality of bump lands 3 were changed, but the opening diameters of the plurality of openings 9a formed in the printing mask 9 were constant.

  FIG. 25 shows a plan view of an example of the print mask 9 used when the solder paste 8 is printed on the plurality of bump lands 3 formed on the first main surface 1 x of the mounting substrate 1. FIG. 25A is a plan view of the print mask 9 facing the A area where the first BGA 10a is mounted, and FIG. 25B is a plan view of the print mask 9 facing the B area where the second BGA 10b is mounted. is there.

  As shown in FIG. 25 (a), the print mask 9 facing the A region of the first main surface 1x of the mounting substrate 1 is opposed to the plurality of bump lands 3 formed in the A region. A plurality of openings 9a having the same opening diameter are formed. Further, as shown in FIG. 25B, the print mask 9 facing the B region of the first main surface 1x of the mounting substrate 1 faces the bump lands 3 formed in the B region. In addition, a plurality of openings 9a having the same opening diameter are formed.

  FIGS. 26A and 26B are an arrangement diagram of a plurality of bump lands 3 formed on the first main surface 1x of the mounting substrate 1 in the region (A region) where the first BGA 10a is mounted and a second BGA 10b, respectively. The arrangement | sequence diagram of the several bump land 3 formed in the 1st main surface 1x of the mounting board | substrate 1 of the area | region (B area | region) to be mounted is shown.

  As shown in FIG. 26A, the A region of the first main surface 1x of the mounting substrate 1 faces a plurality of solder balls (BGA balls) 12a supplied to the first BGA 10a mounted in the A region. As described above, the plurality of bump lands 3 are arranged in consideration of the pitch and dimensions of the plurality of solder balls (BGA balls) 12a. The surfaces and side surfaces of the plurality of bump lands 3 are exposed from the openings 7 provided in the protective film 4 covering the first main surface 1x of the mounting substrate 1.

  However, since the shape of the first BGA 10a when it is returned to room temperature after the reflow treatment is a convex shape that protrudes its central portion in the surface direction, the bridge of the solder ball (conduction path) 13 and the solder ball (conduction path) ) There is concern about 13 balls falling. Therefore, as shown in FIG. 26 (a), a bump land 3 having a relatively small first diameter is formed at the center of the A region of the mounting substrate 1, and solder balls (conduction paths) are formed. 13 is formed high. On the other hand, bump lands 3 having a second diameter having a relatively large diameter (a diameter larger than the first diameter) are formed at the four corners (corner portions) of the outer peripheral area of the area A of the mounting substrate 1. Then, the solder ball (conduction path) 13 having a low protrusion and a small protrusion from the bump land 3 is formed. Then, bump lands 3 having a third diameter larger than the first diameter and smaller than the second diameter are formed in areas other than the central portion and the four corners (corner portions) of the A region of the mounting substrate 1.

  In this way, by changing the size of the diameter of the bump land 3 formed on the first main surface 1x of the mounting substrate 1, it is relatively low at the four corners (corner portions) of the outer peripheral region of the A region of the mounting substrate 1. Since the solder ball (conduction path) 13 having a small protrusion from the bump land 3 is formed, bridging of the solder ball (conduction path) 13 can be prevented. In addition, since the relatively high solder ball (conduction path) 13 is formed at the center of the A region of the mounting substrate 1, it is possible to prevent the solder ball (conduction path) 13 from falling.

  Similarly, as shown in FIG. 26 (b), a plurality of solder balls (BGA balls) 12b supplied to the second BGA 10b mounted in the B region are provided in the B region of the first main surface 1x of the mounting substrate 1. A plurality of bump lands 3 are arranged in consideration of the pitch and dimensions of the plurality of solder balls (BGA balls) 12b. The surfaces and side surfaces of the plurality of bump lands 3 are exposed from the openings 7 provided in the protective film 4 covering the first main surface 1x of the mounting substrate 1.

  However, since the shape of the second BGA 10b when it is returned to room temperature after the reflow process is a concave shape with its central portion protruding in the back surface direction, there is a concern that the solder paste 8 and the solder ball (BGA ball) 12b are not fused. Is done. Therefore, as shown in FIG. 26 (b), bump lands 3 having a relatively small fourth diameter are formed at the four corners (corner portions) of the outer peripheral region of the B region of the mounting substrate 1, The solder balls (conduction paths) 13 are formed high. Bump lands 3 having a fifth diameter larger than the fourth diameter are formed in regions other than the four corners (corner portions) of the mounting substrate 1.

  In this way, by changing the size of the diameter of the bump land 3 formed on the first main surface 1x of the mounting substrate 1, it is relatively high at the four corners (corner portions) of the outer peripheral region of the B region of the mounting substrate 1. Since the solder ball (conduction path) 13 is formed, unfusion of the solder paste 8 and the solder ball (BGA ball) 12b can be prevented.

  In the area A of the mounting substrate 1 shown in FIG. 26A, three types of bump lands 3 having different diameters (first diameter, second diameter, and third diameter) are formed, and FIG. Two types (fourth and fifth diameters) of bump lands 3 having different diameters are formed in the B region of the mounting substrate 1 shown in FIG. 1, but it goes without saying that the present invention is not limited to this. For example, four or more types of bump lands 3 having different diameters may be formed in the A region of the mounting substrate 1, and three or more types of bump lands 3 having different diameters may be formed in the B region of the mounting substrate 1. it can.

  In the second embodiment, by changing the dimensions of the plurality of bump lands 3 formed on the first main surface 1x of the mounting substrate 1, solder balls (conduction paths) 13 having a shape suitable for the placement location are provided. The case of forming is described. Similarly, by changing the dimensions of the plurality of bump lands 5 formed on the second main surface 1y of the mounting substrate 1, the second main surface 1y of the mounting substrate 1 has a shape suitable for the arrangement location. Solder balls (conduction paths) 13 can be formed.

  Further, without changing the dimensions of the plurality of bump lands 3 formed on the first main surface 1x of the mounting substrate 1, the dimensions of the plurality of bump lands 30 formed on the back surface of the first BGA 10a (opening of the protective film). The solder balls (conduction paths) 13 having a shape suitable for the placement location may be formed by changing the dimensions of the bump lands 30 exposed from the portion. Alternatively, the dimensions of the plurality of bump lands 3 formed on the first main surface 1x of the mounting substrate 1 and the dimensions of the plurality of bump lands 30 formed on the back surface of the first BGA 10a (exposed from the opening of the protective film). It is also possible to form solder balls (conduction paths) 13 having a shape suitable for the place of placement by changing both the dimensions of the bump lands 30 provided.

  Moreover, although the opening diameter of the some opening part 9a formed in the printing mask 9 was made constant, you may form the opening part 9a from which an opening diameter differs mutually.

  As described above, according to the second embodiment, similarly to the first embodiment described above, a problem (solder paste) that occurs when the BGA 10 is mounted on the first main surface 1x or the second main surface 1y of the mounting substrate 1 is mounted. 8 and the solder ball (BGA ball) 12 can be prevented from being fused, the bridge of the solder ball (conduction path) 13, and the ball drop of the solder ball (conduction path) 13.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  For example, in the above-described embodiment, the case where the BGA or other mounting component is mounted on both the first main surface of the mounting substrate and the second main surface on the opposite side is described. However, the BGA is mounted only on one surface of the mounting substrate. It can also be applied to mounting. Even when the BGA is mounted only on one side of the mounting substrate, unfused solder paste and solder balls (BGA balls) or bridges of the solder balls (conducting paths) are generated. Can be solved.

  The present invention can also be applied to a POP (Package On Package) having a three-dimensional stacked mounting structure using BGA.

  The present invention can be applied to an electronic device in which a semiconductor device having a plurality of arrayed ball-shaped external terminals on the back surface thereof is mounted on a mounting substrate.

DESCRIPTION OF SYMBOLS 1 Mounting substrate 1x 1st main surface 1y 2nd main surface 2 Base material 2x 1st main surface 2y 2nd main surface 3 Bump land (bump land for semiconductor devices, electrode pad)
4 Protective film (insulating film)
5 Bump land (Bump land for semiconductor devices, electrode pad)
6 Protective film (insulating film)
7 Opening 8 Solder paste (Solder paste for semiconductor device)
9 Print Mask 9a Opening 10 BGA (Semiconductor Device)
10a, 10x 1st BGA
10b, 10y 2nd BGA
10c 3rd BGA
10d First mounting component 10e Second mounting component 11 Heating / cooling tank 12, 12a, 12b, 12c, 12y Solder ball (BGA ball)
12d, 12e Electrode 13 Solder ball (conduction path)
14 Spring 15 Wiring board 15x Upper surface (surface)
15y bottom (back)
16 Semiconductor chip 17 Adhesive (die bond material)
18 Electrode pad 19 Bonding lead (electrode pad)
20 Protective film 21 Bump land (electrode pad)
22 Protective film 23 Through hole (via)
24 Conductive member (wire)
25 Resin sealing body (sealing body)
26 Solder paste (Solder paste for semiconductor devices)
27 Print Mask 27a Opening 30 Bump Land 31 Protective Film

Claims (18)

A semiconductor device mounting method including the following steps:
(A) a first wiring board, a plurality of first bump lands formed on a lower surface of the first wiring board, and a plurality of first solder balls formed on the plurality of first bump lands. Preparing a semiconductor device;
(B) supplying a plurality of first semiconductor device solder pastes to the plurality of first semiconductor device bump lands formed on the first main surface of the mounting substrate;
(C) The first main part of the mounting substrate through the plurality of first semiconductor device solder pastes so that the plurality of first solder balls and the plurality of first semiconductor device bump lands are opposed to each other. Disposing the first semiconductor device on a surface;
(D) Reflow treatment is performed on the mounting substrate on which the first semiconductor device is mounted, so that the plurality of first solder balls and the plurality of first semiconductor device solder pastes are melted. Forming a path;
here,
Before the step (b), the amount of warpage of the first semiconductor device at each position of the plurality of first bump lands is measured by a first analysis that measures the distribution of warpage occurring in the first semiconductor device. Further, a calibration curve relating to the shape of each of the plurality of first solder balls is calculated by a second analysis,
In the step (b), after calculating the optimum supply amount of the first semiconductor device solder paste in each of the plurality of first semiconductor device bump lands based on the results of the first and second analyses. The plurality of first semiconductor device solder pastes are supplied to the plurality of first semiconductor device bump lands. The method for mounting a semiconductor device according to claim 1,
In the step (a), the first semiconductor device having the plurality of first solder balls supplied to the plurality of first bump lands by a ball supply method is prepared.
In the step (b), the plurality of first semiconductor device solder pastes are supplied to the plurality of first semiconductor device bump lands by a printing method using a print mask having a plurality of openings. Mounting method of semiconductor device. In the mounting method of the semiconductor device according to claim 2,
The first semiconductor device includes:
The first wiring substrate made of glass epoxy resin and having an upper surface, a lower surface opposite to the upper surface, and the plurality of first bump lands formed on the lower surface;
A semiconductor chip made of silicon and having a main surface, a back surface opposite to the main surface, and a semiconductor element formed on the main surface, and mounted on the upper surface of the first wiring board;
An epoxy resin and a sealing body for sealing the semiconductor chip;
The plurality of first solder balls formed on each of the plurality of first bump lands formed on the lower surface of the first wiring board;
A method for mounting a semiconductor device, comprising: 4. The method of mounting a semiconductor device according to claim 3, further comprising the following steps after the step (d):
(E) a second wiring board, a plurality of second bump lands formed on the lower surface of the second wiring board, and a second solder ball formed on the plurality of second bump lands. Preparing a semiconductor device;
(F) supplying a plurality of second semiconductor device solder pastes to a plurality of second semiconductor device bump lands formed on a second main surface opposite to the first main surface of the mounting substrate;
(G) The second main part of the mounting substrate through the plurality of second semiconductor device solder pastes so that the plurality of second solder balls and the plurality of second semiconductor device bump lands face each other. Disposing the second semiconductor device on a surface;
(H) Reflow processing is performed on the mounting substrate on which the second semiconductor device is mounted, so that the plurality of second solder balls and the plurality of second semiconductor device solder pastes are melted. Forming a path;
here,
Before the step (f), the amount of warpage of the second semiconductor device at each position of the plurality of second bump lands is determined by the first analysis that measures the distribution of warpage generated in the second semiconductor device. And further, a calibration curve related to the shape of each of the plurality of second solder balls is calculated by the second analysis,
In the step (f), after calculating the optimum supply amount of the solder paste for the second semiconductor device in each of the plurality of bump lands for the second semiconductor device based on the results of the first and second analysis, The plurality of second semiconductor device solder pastes are supplied to the plurality of second semiconductor device bump lands. In the mounting method of the semiconductor device according to claim 4,
The semiconductor device mounting method, wherein the plurality of first solder balls and the first semiconductor device solder paste are substantially free of lead. In the mounting method of the semiconductor device according to claim 5,
The planar shape of the surface of the first semiconductor device is a quadrangle,
When the central portion of the first semiconductor device mounted on the mounting substrate is deformed so as to protrude from the back surface side to the front surface side of the first semiconductor device, the plurality of first semiconductor device bumps The amount of the solder paste for the first semiconductor device supplied to the bump land for the first semiconductor device formed at a position facing the corner of the first semiconductor device in the land is different from that of the first semiconductor device. A method of mounting a semiconductor device, wherein the step (b) is performed so that the amount of the solder paste for the first semiconductor device supplied to the bump land is reduced. The semiconductor device mounting method according to claim 6,
The step (a) further includes the following steps:
(A1) supplying a plurality of first solder ball solder pastes to the plurality of first bump lands of the first semiconductor device;
(A2) disposing the plurality of first solder balls on the plurality of first bump lands via the plurality of first solder ball solder pastes;
(A3) A reflow process is performed on the first semiconductor device on which the plurality of first solder balls are mounted, thereby melting the plurality of first solder balls and the plurality of first solder ball solder pastes. Forming a third solder ball. In the mounting method of the semiconductor device according to claim 5,
The planar shape of the surface of the first semiconductor device is a quadrangle,
When the central portion of the first semiconductor device mounted on the mounting substrate is deformed so as to protrude from the front surface side to the back surface side of the first semiconductor device, the plurality of first semiconductor device bumps The amount of the solder paste for the first semiconductor device supplied to the bump land for the first semiconductor device formed at a position facing the corner of the first semiconductor device in the land is different from that of the first semiconductor device. A method of mounting a semiconductor device, wherein the step (b) is performed such that the amount of the solder paste for the first semiconductor device supplied to the bump land is increased. The semiconductor device mounting method according to claim 8,
The step (a) further includes the following steps:
(A1) supplying a plurality of first solder ball solder pastes to the plurality of first bump lands of the first semiconductor device;
(A2) disposing the plurality of first solder balls on the plurality of first bump lands via the plurality of first solder ball solder pastes;
(A3) A reflow process is performed on the first semiconductor device on which the plurality of first solder balls are mounted, thereby melting the plurality of first solder balls and the plurality of first solder ball solder pastes. Forming a third solder ball. A semiconductor device mounting method including the following steps:
(A) a first wiring board, a plurality of first bump lands formed on a lower surface of the first wiring board, and a plurality of first solder balls formed on the plurality of first bump lands. Preparing a semiconductor device;
(B) supplying a plurality of first semiconductor device solder pastes to the plurality of first semiconductor device bump lands formed on the first main surface of the mounting substrate;
(C) The first main part of the mounting substrate through the plurality of first semiconductor device solder pastes so that the plurality of first solder balls and the plurality of first semiconductor device bump lands are opposed to each other. Disposing the first semiconductor device on a surface;
(D) Reflow treatment is performed on the mounting substrate on which the first semiconductor device is mounted, so that the plurality of first solder balls and the plurality of first semiconductor device solder pastes are melted. Forming a path;
here,
Before the step (b), the amount of warpage of the first semiconductor device at each position of the plurality of first bump lands is measured by a first analysis that measures the distribution of warpage occurring in the first semiconductor device. Further, a calibration curve relating to the shape of each of the plurality of first solder balls is calculated by a second analysis,
In the step (b), the mounting board on which the plurality of first semiconductor device bump lands having the optimum diameters calculated based on the results of the first and second analyzes are formed is prepared. . In the mounting method of the semiconductor device according to claim 10,
In the step (a), the first semiconductor device having the plurality of first solder balls supplied to the plurality of first bump lands by a ball supply method is prepared.
In the step (b), the plurality of first semiconductor device solder pastes are supplied to the plurality of first semiconductor device bump lands by a printing method using a print mask having a plurality of openings. Mounting method of semiconductor device. In the mounting method of the semiconductor device according to claim 11,
The first semiconductor device includes:
The first wiring substrate made of glass epoxy resin and having an upper surface, a lower surface opposite to the upper surface, and the plurality of first bump lands formed on the lower surface;
A semiconductor chip made of silicon and having a main surface, a back surface opposite to the main surface, and a semiconductor element formed on the main surface, and mounted on the upper surface of the first wiring board;
An epoxy resin and a sealing body for sealing the semiconductor chip;
The plurality of first solder balls formed on each of the plurality of first bump lands formed on the lower surface of the first wiring board;
A method for mounting a semiconductor device, comprising: 13. The method of mounting a semiconductor device according to claim 12, further comprising the following steps after the step (d):
(E) a second wiring board, a plurality of second bump lands formed on the lower surface of the second wiring board, and a second solder ball formed on the plurality of second bump lands. Preparing a semiconductor device;
(F) supplying a plurality of second semiconductor device solder pastes to a plurality of second semiconductor device bump lands formed on a second main surface opposite to the first main surface of the mounting substrate;
(G) The second main part of the mounting substrate through the plurality of second semiconductor device solder pastes so that the plurality of second solder balls and the plurality of second semiconductor device bump lands face each other. Disposing the second semiconductor device on a surface;
(H) Reflow processing is performed on the mounting substrate on which the second semiconductor device is mounted, so that the plurality of second solder balls and the plurality of second semiconductor device solder pastes are melted. Forming a path;
here,
Before the step (f), the amount of warpage of the second semiconductor device at each position of the plurality of second bump lands is determined by the first analysis that measures the distribution of warpage generated in the second semiconductor device. And further, a calibration curve related to the shape of each of the plurality of second solder balls is calculated by the second analysis,
In the step (f), the mounting substrate on which the plurality of bump lands for the second semiconductor device having the optimum diameters calculated based on the results of the first and second analyzes are formed is prepared. . The method for mounting a semiconductor device according to claim 13,
The semiconductor device mounting method, wherein the plurality of first solder balls and the first semiconductor device solder paste are substantially free of lead. 15. The method of mounting a semiconductor device according to claim 14,
The planar shape of the surface of the first semiconductor device is a quadrangle,
When the central portion of the first semiconductor device mounted on the mounting substrate is deformed so as to protrude from the back surface side to the front surface side of the first semiconductor device, the plurality of first semiconductor device bumps The diameter of the bump land for the first semiconductor device formed at a position of the land facing the corner of the first semiconductor device is larger than the diameter of the bump land for the other first semiconductor device. A method of mounting a semiconductor device, wherein the plurality of bump lands for the first semiconductor device are formed. The method of mounting a semiconductor device according to claim 15,
The step (a) further includes the following steps:
(A1) supplying a plurality of first solder ball solder pastes to the plurality of first bump lands of the first semiconductor device;
(A2) disposing the plurality of first solder balls on the plurality of first bump lands via the plurality of first solder ball solder pastes;
(A3) A reflow process is performed on the first semiconductor device on which the plurality of first solder balls are mounted, thereby melting the plurality of first solder balls and the plurality of first solder ball solder pastes. Forming a third solder ball. 15. The method of mounting a semiconductor device according to claim 14,
The planar shape of the surface of the first semiconductor device is a quadrangle,
When the central portion of the first semiconductor device mounted on the mounting substrate is deformed so as to protrude from the front surface side to the back surface side of the first semiconductor device, the plurality of first semiconductor device bumps The diameter of the bump land for the first semiconductor device formed at a position facing the corner of the first semiconductor device in the land is made smaller than the diameter of the bump land for the other first semiconductor device. A method of mounting a semiconductor device, wherein the plurality of bump lands for the first semiconductor device are formed. The method for mounting a semiconductor device according to claim 17,
The step (a) further includes the following steps:
(A1) supplying a plurality of first solder ball solder pastes to the plurality of first bump lands of the first semiconductor device;
(A2) disposing the plurality of first solder balls on the plurality of first bump lands via the plurality of first solder ball solder pastes;
(A3) A reflow process is performed on the first semiconductor device on which the plurality of first solder balls are mounted, thereby melting the plurality of first solder balls and the plurality of first solder ball solder pastes. Forming a third solder ball.