JP2017143196A - Electronic device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic device that is able to prolong a period of time that the entire device functions normally, even in a case where a plurality of electronic components are mounted thereon, and to provide a manufacturing method for the electronic device.SOLUTION: An electronic device comprises: two or more types of electronic components, a circuit board 20, and connection solders 30 connecting the electronic components and the circuit board 20. The electronic component comprises: a first component 10 connected by means of the connection solder 30 of ball form; and second components 10A, 10B connected by means of the connection solder 30 of skirt form. The connection solders 30 include: a low strength solder 31 with predetermined tensile strength, and a high strength solder 32 greater in tensile strength than the low strength solder 31. The first component 10 is connected by means of the connection solders 30 including the low strength solders 31 more than the high strength solders 32. The second components 10A, 10B are connected by means of the connection solders 30 including the high strength solders 32 than the low strength solders 31.SELECTED DRAWING: Figure 1

Description

  The disclosure in this specification relates to an electronic device in which an electronic component is mounted on a circuit board via solder, and a manufacturing method thereof.

  Conventionally known electronic devices include electronic components, circuit boards, and solder. Electronic components such as passive elements and active elements are mounted on a circuit board via solder. The solder connects the electrode of the electronic component and the wiring on the circuit board, and electrically connects the electronic component and the circuit board. Here, the solder connecting the electronic component and the circuit board is referred to as normal solder.

  Consider a case where an electronic device is placed in an environment where the outside air temperature changes greatly. Under such an environment, the electronic component and the circuit board repeatedly expand and contract. The electronic component and the circuit board have a difference in coefficient of linear expansion, and the amount of change in length due to expansion and contraction differs. Therefore, shear stress is generated in the normal solder connecting the electronic component and the circuit board due to the difference in the amount of change due to the expansion and contraction. This shear stress is repeatedly applied to the solder under the above-described environment. As a result, normal solder fatigues the metal, cracks, and weakens the force to connect the electronic component and the circuit board.

  Therefore, Patent Document 1 discloses a solder having a sufficient shear strength against the above-described shear stress. The solder of patent document 1 contains Ag, Cu, Sb, Ni, Bi, and Sn as the component. That is, the solder of patent document 1 has sufficient intensity | strength with respect to said shear stress. Therefore, even if the above-described shear stress is repeatedly applied to the solder, it is possible to lengthen the time until the solder cracks due to metal fatigue.

Patent No. 5811304

  Here, the electronic device has a plurality of types, for example, QFP (Quad Flat Package), BGA (Ball Grid Array), chip resistor, chip capacitor, and the like.

  When these plural types of electronic components are connected to the circuit board via solder, the shape of the solder may be a ball shape or a skirt shape depending on the type of the electronic component.

  When the solder of Patent Document 1 is used, even if the shear stress is applied to the solder, it is difficult for the solder to crack. On the other hand, the shear stress is transmitted through the solder, and the circuit board It may be transmitted to the wiring.

  When the shape of the solder is a skirt shape, since a gentle skirt is formed along the wiring, the shear stress is not easily transmitted to the wiring on the circuit board. However, in the case of the ball shape, unlike the skirt shape, the skirt is not formed, and the above shear stress is easily transmitted to the circuit board. Therefore, damage such as cracking of the circuit board, for example, wiring, occurs due to the shear stress.

  For this reason, the circuit board to which a plurality of types of electronic components are connected via the solder of Patent Document 1 is a place where the ball-shaped solder is connected even if the base-shaped solder is not damaged. May be damaged. Therefore, the period during which the electronic device operates normally depends on the degree of damage to the circuit board caused by the ball-shaped solder.

  Accordingly, an object of the present disclosure is to provide an electronic device and a method for manufacturing the same that can extend a period during which the entire device functions normally even when a plurality of electronic components are mounted.

  The present disclosure relates to a circuit board (20) having wiring (22) on a mounting surface (21), which is a surface on which electronic components are mounted, and at least two or more types of electronic components having electrodes (11). ) And connection solder (30) for electrically and mechanically connecting the electronic component and the circuit board (20), and the connection solder (30) is at least a mounting surface (21 on the electrode (11)) ) Between the electrode facing surface 12, which is the surface facing the electrode facing surface 12, and the wiring facing surface 23, which is the surface facing the electrode facing surface 12. The first component (10) connected to the circuit board (20) with the ball-shaped connecting solder (30) and the second component connected to the circuit board (20) with the base-shaped connecting solder (30) (10A, 10B) and connection solder (30 Includes a low-strength solder (31) having a predetermined tensile strength and a high-strength solder (32) having a higher tensile strength than the low-strength solder (31), and the first component (10) includes: The second component (10A, 10B) is connected to the circuit board (20) with a connection solder (30) having more low-strength solder (31) than the high-strength solder (32), and the second component (10A, 10B) is higher than the low-strength solder (31). The electronic device is connected to the circuit board (20) with connection solder (30) with a lot of strength solder (32).

  According to the electronic device disclosed herein, the following operational effects can be obtained.

  It is assumed that the first component connected to the circuit board with the ball-shaped connection solder is easily transmitted to the wiring. Here, the ball-shaped connection solder contains more low-strength solder than high-strength solder. As a result, the shear stress can be easily dispersed by the connection solder itself while securing the shear strength of the connection solder, so that the concentration of the shear stress on the circuit board and wiring can be alleviated.

  On the other hand, in the second component connected to the circuit board with the skirt-shaped connection solder, it is assumed that the above-described shear stress is concentrated on the connection solder itself. Here, the skirt-shaped connection solder contains more high-strength solder than low-strength solder. Thereby, even if the above-described shear stress is applied to the connection solder itself, it is possible to lengthen the period until the connection solder is fatigued by metal and cracks occur.

  Therefore, it is possible to extend the period during which the electronic device functions normally as compared with the conventional electronic device by using the connection solder in which the ratio of the low strength solder and the high strength solder is adjusted according to the type of the electronic component. it can.

  The present disclosure also provides a circuit board having at least two or more types of electronic components having electrodes (11) and wiring (22) on a mounting surface (21) which is a surface on which the electronic components are mounted. (20) and a connection solder (30) for electrically and mechanically connecting the electronic component and the circuit board (20), and at least a part of the connection solder 30 is mounted on the electrode (11). Between the electrode facing surface (12) which is the surface facing the surface (21) and the wiring facing surface (23) where a part of the wiring (22) is facing the electrode facing surface (12) The electronic component includes a first component (10) connected to the circuit board (20) with a ball-shaped connection solder (30) and a circuit board (20 A second part (10A, 10B) connected to The connection solder (30) includes a low-strength solder (31) having a predetermined tensile strength and a high-strength solder (32) having a higher tensile strength than the low-strength solder (31). The component (10) is connected to the circuit board (20) with connection solder (30), which has more low-strength solder (31) than high-strength solder (32), and the second component (10A, 10B) has low strength. A method of manufacturing an electronic device connected to a circuit board (20) with a connection solder (30) having more high-strength solder (32) than solder (31), wherein the low-strength solder (31) and the high-strength solder (32 ) Is applied to the wiring (22) so that the low-strength solder (31) is larger on the one solder than the first component (10) and the high-strength solder (32). Place one solder and the other On the solder, arrange the other solder so that the second component (10A, 10B) and the high-strength solder (32) are larger than the low-strength solder (31), reflow one solder and the other solder, This is a method of manufacturing an electronic device that electrically connects the first component (10) and the second component (10A, 10B) and the circuit board (20) by forming a connection solder (30).

  According to the method for manufacturing an electronic device disclosed herein, the following effects can be obtained.

  As described above, in the first component connected to the circuit board with the ball-shaped connection solder, it is assumed that the shear stress is concentrated on the boundary surface between the connection solder and the wiring on the circuit board.

  On the other hand, in the second component connected to the circuit board with the skirt-shaped connection solder, it is assumed that the above-described shear stress is concentrated on the connection solder itself.

  In the disclosed method for manufacturing an electronic device, when the first component is connected to the circuit board, the first component, the low-strength solder, and the high-strength solder in an amount smaller than the low-strength solder are arranged on the circuit board. . When the second component is connected to the circuit board, the second component, the low-strength solder, and the high-strength solder in an amount larger than the low-strength solder are arranged on the circuit board. Then, by reflow, connection solder is formed to electrically connect the electronic component and the circuit board. Therefore, since the connection solder in which the amount of the low-strength solder and the high-strength solder is adjusted can be formed according to the type of the electronic component connected to the circuit board, the above-described electronic device can be manufactured.

  The disclosed embodiments of the present specification employ different technical means to achieve each purpose. The reference numerals in parentheses described in the claims and in this section exemplarily show a correspondence relationship with the part of the present embodiment described later, and are not intended to limit the technical scope. The objects, features, and advantages disclosed in this specification will become more apparent with reference to the following detailed description and accompanying drawings.

It is a figure of the electronic device of this embodiment. It is sectional drawing which cut | disconnected the electronic device of this embodiment by the II-II line | wire of FIG. It is an enlarged view of the 1st component and circuit board of this embodiment. It is an enlarged view of the 2nd component and circuit board of this embodiment. It is an enlarged view of the 2nd component and circuit board of this embodiment. It is an enlarged view of the 3rd component and circuit board of this embodiment. It is an enlarged view at the time of the 1st component arrangement in the manufacturing method of this embodiment. It is an enlarged view at the time of the 1st component connection in the manufacturing method of this embodiment. It is an enlarged view at the time of the low intensity | strength solder application | coating in the manufacturing method of this embodiment. It is an enlarged view at the time of 2nd components arrangement | positioning in the manufacturing method of this embodiment. It is an enlarged view at the time of the high intensity | strength solder application | coating in the manufacturing method of this embodiment. It is an enlarged view at the time of arrangement | positioning 2nd components in the manufacturing method of this embodiment. It is an enlarged view at the time of the high intensity | strength solder application | coating in the manufacturing method of this embodiment. It is an enlarged view at the time of arrangement | positioning 3rd components in the manufacturing method of this embodiment. It is an enlarged view at the time of the high intensity | strength solder application | coating in the manufacturing method of this embodiment.

  The form for carrying out this indication is explained, referring to drawings.

  In the present embodiment, as an example, the electronic device 1 shown in FIGS. 1 and 2 is employed. The electronic device 1 is an electronic control device that can be mounted on a vehicle, for example. Examples of the electronic control device include an engine control device, a power steering control device, and a brake control device. Furthermore, the electronic device 1 is mounted in an environment where the ambient temperature changes greatly, such as an engine room of a vehicle. That is, the electronic device 1 is mounted in an environment where the temperature changes in a range of about −30 degrees to about 100 degrees, for example.

  First, the configuration of the electronic device 1 will be described. The electronic device 1 has a plurality of types of electronic components, a circuit board 20, a connection solder 30, and the like. Therefore, the electronic device 1 can also be referred to as an ECU (Electronic Control Unit).

  As shown in FIGS. 1 and 2, there are four types of electronic components, for example, a BGA 10, a chip component 10A, a semiconductor package 10B, and a tall component 10C. The BGA 10 corresponds to the first component in the claims, and similarly, the chip component 10A and the semiconductor package 10B correspond to the second component, and the tall component 10C corresponds to the third component. In the present embodiment, as shown in FIG. 2, an electronic device 1 in which these electronic components are mounted on both surfaces of the circuit board 20 is employed. However, the present invention can be employed even in the electronic device 1 in which electronic components are mounted only on one side of the circuit board 20. Further, with respect to FIG. 3 and subsequent figures, only the electronic components mounted on one surface are shown for the sake of simplicity.

The BGA 10 functions as, for example, a central processing unit or a nonvolatile memory. The BGA 10 is a semiconductor chip covered with a resin. Therefore, it is considered that the linear expansion coefficient of the BGA 10 is almost the same as the general linear expansion coefficient of the resin covering the chip, so that the value is 10 × 10 ⁻⁶ / K or more and 60 × 10 ⁻⁶ / K or less. Take.

  As shown in FIG. 3, the BGA 10 has the electrode 11 only on the surface connected to the circuit board 20. In other words, the BGA 10 has the electrode 11 formed only on the surface facing the circuit board 20. Further, the BGA 10 has an electrode facing surface 12 that is a surface facing an after-mentioned first land 220 in the electrode 11.

  However, the first component is not limited to the BGA 10. The BGA 10 is an electronic component generally called an area type in which a plurality of electrodes 11 are exposed on a surface facing the circuit board 20. Therefore, this embodiment may be another area type electronic component that replaces the BGA 10, and the first component is an FCBGA (Flip Chip Ball Grid Array), a CSP (Chip Size Package), and an LGA (Land Grid Array). Etc. can also be employed.

The chip component 10A functions as a passive element such as a chip resistor or a chip capacitor, for example. The chip component 10A is mainly made of ceramic. Therefore, the linear expansion coefficient of the chip component 10A is approximately 6 × 10 ⁻⁶ / K or more and 7 × 10 ⁻⁶ / K or less.

  As illustrated in FIG. 4, the chip component 10 </ b> A has a rectangular parallelepiped shape, and two electrodes 11 are formed so as to cover both ends of the rectangular parallelepiped. Similarly to the BGA 10, the chip component 10 </ b> A has an electrode facing surface 12 that is a surface facing the later-described second land 220 </ b> A of the electrode 11.

As shown in FIG. 5, the semiconductor package 10 </ b> B has a main body portion in which a semiconductor chip is covered with a resin, and a shape in which the electrode 11 protrudes from a side surface of the main body portion. Thus, the semiconductor package 10B is different from the BGA 10 in the electrode configuration. Therefore, the linear expansion coefficient of the semiconductor package 10B takes a value of 10 × 10 ⁻⁶ / K or more and 60 × 10 ⁻⁶ / K or less similarly to the BGA 10.

  Similarly to the BGA 10, the semiconductor package 10 </ b> B has an electrode facing surface 12 that is a surface facing a later-described third land 220 </ b> B in the electrode 11. Furthermore, the electrode 11 of the semiconductor package 10B is bent twice along the way. After the electrode 11 bends twice, it extends in the same direction as the direction protruding from the side surface. Such an electrode 11 is generally called a gull wing structure or a centipede foot structure.

  However, the second component is not limited to the chip component 10A and the semiconductor package 10B. In short, the second component has the electrode 11 on its side surface, and the electrode 11 only needs to have the electrode facing surface 12 facing the land.

  The semiconductor package 10B is a surface-mount type electronic component having electrodes protruding from the side surface of the main body. Therefore, the present embodiment may be another surface-mount type electronic component that replaces the semiconductor package 10B, and may employ QFP (Quad Flat Package), QFJ (Quad Flat J-leaded Package), and the like.

  As shown in FIG. 2, the tall component 10C is an electronic component that is taller than the BGA 10, the chip component 10A, and the semiconductor package 10B. The height of the electronic component is the length of the electronic component in a direction perpendicular to the mounting surface 21 that is the surface of the circuit board 20 on which the electronic component is mounted. The tall component 10C functions as, for example, an aluminum electrolytic capacitor or a solenoid. The tall component 10C is larger in size than the BGA 10, the chip component 10A, and the semiconductor package 10B.

  As shown in FIG. 6, the tall component 10 </ b> C has the electrode 11 on the side mounted on the circuit board 20. The electrode 11 is continuously formed up to the side surface of the tall component 10C. Similar to the BGA 10, the chip component 10A, and the semiconductor package 10B, the tall component 10C has an electrode facing surface 12 that is a surface facing a later-described fourth land 220C of the electrode 11.

  However, the third component is not limited to the tall component 10C. In short, the third component only needs to be taller than the first component and the second component.

The circuit board 20 is obtained by forming conductive wirings 22 on a base material mainly composed of ceramic, resin, or the like. Therefore, the linear expansion coefficient of the circuit board 20 generally matches the linear expansion coefficient of ceramic or resin. Therefore, the linear expansion coefficient of the circuit board 20 is 12 × 10 ⁻⁶ / K or more and 16 × 10 ⁻⁶ / K or less.

  The circuit board 20 has a mounting surface 21 that is a surface on which electronic components are mounted. As shown in FIGS. 3 to 6, the wiring 22 has a land, an internal wiring 221 and a via 222. The land is a part formed on the mounting surface 21 in the wiring 22. The circuit board 20 includes a first land 220, a second land 220A, a third land 220B, and a fourth land 220C as lands. The first land 220 is formed on the mounting surface 21. In the first land 220, a surface facing the electrode facing surface 12 of the BGA 10 is a wiring facing surface 23. Similarly, the second land 220A and the third land 220B face the electrode facing surface 12 of the chip component 10A and the semiconductor package 10B, and the fourth land 220C faces the electrode facing surface 12 of the tall component 10C. The surface that is present is the wiring facing surface 23.

  Note that the internal wiring 221 and the via 222 are portions formed in the base material in the wiring 22. The internal wiring 221 is formed in layers inside the circuit board 20 in a direction perpendicular to the mounting surface. The internal wiring 221 extends in a direction parallel to the mounting surface 21. The via 222 extends in a direction perpendicular to the mounting surface. The via 222 electrically connects the land and the internal wiring 221. Although not shown, the via 222 electrically connects the internal wirings 221 to each other.

  As shown in FIG. 3, the connection solder 30 electrically and mechanically connects the electrode 11 of the BGA 10 and the first land 220. Hereinafter, the electrical and mechanical connection is simply referred to as connection. The connecting solder 30 that connects the electrode 11 of the BGA 10 and the first land 220 exists between the electrode facing surface 12 and the wiring facing surface 23. In addition, at least a part of the connection solder 30 may exist between the electrode facing surface 12 and the wiring facing surface 23.

  When the BGA 10 and the circuit board 20 are connected, the connection solder 30 has a ball shape. In the ball shape, the cross-sectional area parallel to the mounting surface 21 of the connection solder 30 increases from the electrode facing surface 12 toward the center of the connection solder 30 and from the wiring facing surface 23 toward the center of the connection solder 30. The shape is also larger. In other words, the inclination of the surface of the connection solder 30 becomes perpendicular to the mounting surface 21 as it goes from the electrode facing surface 12 to the center of the connection solder 30, and is also mounted as it goes from the wiring facing surface 23 to the center of the connection solder 30. It is perpendicular to the surface 21.

  As shown in FIG. 4, the connection solder 30 electrically connects the electrode 11 of the chip component 10A and the second land 220A. In this case, the connection solder 30 is present other than between the electrode facing surface 12 and the wiring facing surface 23. Specifically, the connection solder 30 is also formed on a surface perpendicular to the electrode facing surface 12 of the electrode 11, so that the connection solder 30 exists other than between the electrode facing surface 12 and the wiring facing surface 23. . That is, as shown in FIG. 4, when the chip component 10 </ b> A and the circuit board 20 are connected, the connection solder 30 may exist other than between the electrode facing surface 12 and the wiring facing surface 23. .

  Further, as shown in FIG. 5, the connection solder 30 connects the semiconductor package 10B and the third land 220B. In this case, the connection solder 30 is present other than between the electrode facing surface 12 and the wiring facing surface 23 as in the case of the chip component 10A. Specifically, since the connection solder 30 is also formed on a surface perpendicular to the electrode facing surface 12 of the electrode 11, there is the connection solder 30 other than between the electrode facing surface 12 and the wiring facing surface 23. It will be. That is, as shown in FIG. 5, when the semiconductor package 10 </ b> B and the circuit board 20 are connected, the connection solder 30 may exist other than between the electrode facing surface 12 and the wiring facing surface 23. .

  When the chip component 10A and the semiconductor package 10B are connected to the circuit board 20, the connection solder 30 has a skirt shape. The skirt shape is a shape in which a cross-sectional area parallel to the mounting surface 21 of the connection solder 30 increases from the electrode facing surface 12 toward the wiring facing surface 23. In other words, the inclination of the surface of the connection solder 30 approaches parallel to the mounting surface 21 as it goes from the electrode facing surface 12 to the wiring facing surface 23. The base shape can also be referred to as a fillet shape.

  As shown in FIG. 6, the connection solder 30 connects the electrode 11 of the tall component 10C and the fourth land 220C. In this case, the connection solder 30 is present other than between the electrode facing surface 12 and the wiring facing surface 23 as in the case of the chip component 10A and the semiconductor package 10B. The tall component 10C has the electrode 11 on a surface perpendicular to the electrode facing surface 12 in the same manner as the chip component 10A. Therefore, the connection solder 30 is also formed on this vertical surface. Therefore, the connecting solder 30 exists other than between the electrode facing surface 12 and the wiring facing surface 23.

  As shown in FIG. 6, when the tall component 10 </ b> C and the circuit board 20 are connected, the connection solder 30 has a skirt shape as in the case of the chip component 10 </ b> A and the semiconductor package 10 </ b> B.

  The connection solder 30 includes two types of low-strength solder 31 and high-strength solder 32 having different tensile strengths. Here, the tensile strength refers to the magnitude of the force per unit area of the material when the material is broken when a force is applied in the direction of pulling the material. The low-strength solder 31 and the high-strength solder 32 have a predetermined tensile strength.

  The low-strength solder 31 is one of the materials included in the connection solder 30, for example. The low-strength solder 31 mainly contains Sn and Ag at a ratio of 6: 1. The tensile strength of the low-strength solder 31 is 40 MPa or more and 50 MPa or less.

  The high-strength solder 32 is one of the materials included in the connection solder 30, for example. In the high-strength solder 32, Ag is 1% by mass to 4% by mass, Cu is 0.6% by mass to 0.8% by mass, Sb is 1% by mass to 5% by mass, and Ni is 0.01% by mass. More than 0.2% by mass and the rest consists of Sn. The tensile strength of the high-strength solder 32 is 90 MPa or more and 100 MPa or less.

  The ratio of the low-strength solder 31 and the high-strength solder 32 included in the connection solder 30 is a prediction calculated by the endurance test result of the thermal cycle, which is an accelerated test of the environment in which the electronic device 1 is mounted, or by stress analysis such as the finite element method. Based on. For example, in the case of the BGA 10, the connection solder 30 is used to connect the BGA 10 and the circuit board 20. Thereafter, the above durability test or stress analysis is performed. Since it is considered that the circuit board 20 is damaged, the durability test or stress analysis is performed again by adjusting the ratio of the low-strength solder 31 and the high-strength solder 32 included in the connection solder 30 in order to improve this. By repeating these steps, the ratio of the low-strength solder 31 and the high-strength solder 32 contained in the connection solder 30 when connecting the BGA 10 can be optimized.

  The ball-shaped connection solder 30 contains more low-strength solder 31 than high-strength solder 32.

  The skirt-shaped connection solder 30 contains more high-strength solder 32 than low-strength solder 31. Note that the base-shaped connection solder 30 may include only the high-strength solder 32.

  Here, it is assumed that the skirt-shaped connection solder 30 contains more high-strength solder 32 than low-strength solder 31. However, exceptionally, regardless of the shape of the connection solder 30, the connection solder 30 that connects the tall component 10 </ b> C and the circuit board 20 includes more low-strength solder 31 than high-strength solder 32. .

  Note that the electronic device 1 of the present embodiment is connected to the connector 40. The connector 40 is a connection part between the external device and the electronic device 1. As shown in FIG. 1, the connector 40 has a terminal 41 covered with a housing 42. The terminal 41 is a conductive member connected to the circuit board 20.

  In addition, the electronic device 1 of the present embodiment is accommodated in the case 50. The case 50 is mainly made of aluminum. The case 50 protects the electronic device 1 from the outside.

(Manufacturing method of this embodiment)
Here, a method of manufacturing the electronic device 1 will be described with reference to FIGS. The manufacturing method of the electronic device 1 disclosed in this embodiment performs the coating process, the arranging process, and the reflow process in this order. Although each electronic component will be described with reference to FIGS. 7 to 15, a manufacturing process for mounting each electronic component only on one side of the circuit board 20 is shown in order to simplify the drawing. Therefore, the manufacturing method of the electronic apparatus 1 is not limited to the manufacturing method which mounts each electronic component only on one side.

(Coating process)
In the coating process, as shown in FIG. 7, a low-strength solder 31 is applied on each land of the circuit board 20. Specifically, in the application process, the low-strength solder 31 is applied on the first land 220. Further, the low-strength solder 31 is applied on the second land 220A. Further, the low-strength solder 31 is applied on the third land 220B. Then, the low-strength solder 31 is applied on the fourth land 220C. In the application process, a predetermined amount of low-strength solder 31 is applied on the lands by application using a dispenser or the like or screen printing. That is, one low-strength solder 31 may be applied to each land, or the low-strength solder 31 may be applied to all lands at once.

  In the present embodiment, as an example, an application process of applying the low-strength solder 31 onto the land is employed. However, the present invention is not limited to this, and can be adopted even in an application process in which the high-strength solder 32 is applied on the land.

(Arrangement process)
In the placement process, the high-strength solder 32, the BGA 10, the chip part 10A, the semiconductor package 10B, and the tall part 10C are placed on the low-strength solder 31 applied to each land in the coating process. In this arrangement step, each of the BGA 10, the chip component 10A, the semiconductor package 10B, and the tall component 10C will be described individually.

  First, the arrangement of the high-strength solder 32 and the BGA 10 will be described with reference to FIGS. As shown in FIG. 8, in the arranging step, the BGA 10 in a state where the high-strength solder 32 is formed on the electrode 11 using a chip mounter or the like is arranged just above the low-strength solder 31 for the BGA 10. The high strength solder 32 is formed on each of the plurality of electrodes 11.

  As shown in FIG. 9, in the placement step, the BGA 10 to which the high strength solder 32 is applied is placed on the low strength solder 31 on the first land 220. The amount of the high-strength solder 32 formed on the electrode 11 is smaller than the amount of the low-strength solder 31 applied in the application process. That is, in the placement process, a smaller amount of high-strength solder 32 is placed than the amount of low-strength solder 31 predetermined in the coating process. In the placement step, the low-strength solder 31 and the high-strength solder 32 are placed between the electrode facing surface 12 and the wiring facing surface 23.

  Next, the arrangement of the high-strength solder 32 and the chip component 10A will be described with reference to FIGS. As shown in FIG. 10, in the arrangement step, the chip component 10A and the high-strength solder 32 are separately arranged on the low-strength solder 31 for the chip component 10A. That is, in the arranging step, the chip component 10 </ b> A is arranged on the low-strength solder 31 in a state where the high-strength solder 32 is not formed on the electrode 11. In the placement step, the chip component 10A is placed on the low-strength solder 31 using a chip mounter or the like. At this time, in the arranging step, the chip component 10 </ b> A is arranged so that at least a part of the low-strength solder 31 exists between the electrode facing surface 12 and the wiring facing surface 23.

  As shown in FIG. 11, in the placement step, the chip component 10 </ b> A is placed on the low-strength solder 31 and then the high-strength solder 32 is applied. At this time, in the arranging step, the high-strength solder 32 is applied to a portion other than the place where the electrode 11 of the chip component 10A is arranged. The amount of the high-strength solder 32 is larger than the amount of the low-strength solder 31 applied in the application process. That is, in the arranging step, a larger amount of high-strength solder 32 is applied than the amount of low-strength solder 31 predetermined in the application step. The chip component 10 </ b> A and the high-strength solder 32 are disposed on the low-strength solder 31. In the arranging step, the high-strength solder 32 is applied on the low-strength solder 31 using a dispenser or the like.

  Next, the arrangement of the high-strength solder 32 and the semiconductor package 10B will be described with reference to FIGS. As shown in FIG. 12, in the arranging step, the semiconductor package 10B and the high strength solder 32 are separately arranged on the low strength solder 31 for the semiconductor package 10B. That is, the semiconductor package 10 </ b> B is disposed on the low-strength solder 31 in a state where the high-strength solder 32 is not formed on the electrode 11. In the placement step, the semiconductor package 10B is placed using a chip mounter or the like. At this time, in the arranging step, the semiconductor package 10B is arranged so that at least a part of the low-strength solder 31 exists between the electrode facing surface 12 and the wiring facing surface 23, similarly to the chip component 10A.

  As shown in FIG. 13, in the placement step, the semiconductor package 10 </ b> B is placed on the low-strength solder 31 and then the high-strength solder 32 is applied. At this time, in the placement step, the coating is applied to a portion other than the place where the electrode 11 of the semiconductor package 10B is placed. The amount of the high-strength solder 32 is larger than the amount of the low-strength solder 31 applied in the application step, as in the placement step in the chip component 10A. In the placement step, the semiconductor package 10 </ b> B and the high strength solder 32 are placed on the low strength solder 31. In the placement step, the high-strength solder 32 is applied onto the low-strength solder 31 using a dispenser or the like, similarly to the placement step in the chip component 10A.

  The arrangement of the high-strength solder 32 and the tall component 10C will be described with reference to FIGS. As shown in FIG. 14, in the placement step, the tall component 10C and the high strength solder 32 are separately placed on the low strength solder 31 for the tall component 10C. That is, in the arranging step, the tall component 10 </ b> C is arranged on the low-strength solder 31 in a state where the high-strength solder 32 is not formed on the electrode 11. In the placement step, the tall component 10C is placed on the low-strength solder 31 using a chip mounter or the like. At this time, in the arranging step, the tall component 10C is arranged so that at least a part of the low-strength solder 31 exists between the electrode facing surface 12 and the wiring facing surface 23, similarly to the chip component 10A.

  As shown in FIG. 15, in the arranging step, the high-strength solder 32 is applied after the tall component 10 </ b> C is arranged on the low-strength solder 31. The amount of the high-strength solder 32 applied other than the place where the tall component 10C is disposed is larger than the amount of the low-strength solder 31 applied in the application process. In the arranging step, the third component 10 </ b> C and the high strength solder 32 are arranged on the low strength solder 31. In the placement step, the high-strength solder 32 is applied onto the low-strength solder 31 using a dispenser or the like, similarly to the placement step in the chip component 10A and the semiconductor package 10B.

  In the present embodiment, as an example, an arrangement process of arranging the high-strength solder 32 on the low-strength solder 31 is employed. However, the present invention is not limited to this, and in the arranging step, the low-strength solder 31 may be arranged on the high-strength solder 32 applied in the applying step.

(Reflow process)
In the reflow process, the connection solder 30 is formed by melting and curing the low-strength solder 31 and the high-strength solder 32. Then, by forming the connection solder 30, each electronic component and the circuit board 20 are connected.

  In the case of the BGA 10, the low strength solder 31 and the high strength solder 32 between the electrode facing surface 12 and the wiring facing surface 23 are melted by heating. The melted low-strength solder 31 and high-strength solder 32 are mixed with each other by convection. And the connection solder 30 of a molten state is made. The molten connection solder 30 between the electrode facing surface 12 and the wiring facing surface 23 is rounded by the surface tension. Thereafter, the ball-shaped connection solder 30 is formed by curing.

  In the case of the chip component 10A, the low-strength solder 31 and the high-strength solder 32 disposed on the low-strength solder 31 are melted by heating. As in the case of the reflow process in the BGA 10, the molten low-strength solder 31 and the high-strength solder 32 are mixed with each other, and the connection solder 30 in the molten state is formed. The molten connection solder 30 wets and spreads on the surface perpendicular to the electrode facing surface 12 and the wiring facing surface 23 of the chip component 10A. As the connection solder 30 in the molten state wets and spreads, a skirt is formed in the connection solder 30 between the electrode facing surface 12 and the wiring facing surface. Then, the bottom-shaped connection solder 30 is formed by hardening.

  In the case of the semiconductor package 10B, the low-strength solder 31 and the high-strength solder 32 disposed on the low-strength solder 31 are melted by heating. As in the case of the reflow process in the BGA 10 and the chip component 10A, the molten low-strength solder 31 and the high-strength solder 32 are mixed with each other, and the molten connection solder 30 is formed. The molten connection solder 30 wets and spreads on the wiring facing surface 23 of the semiconductor package 10B. Thereafter, as in the case of the chip component 10A, the bottom-shaped connection solder 30 is formed by curing.

  In the case of the tall component 10C, similarly to the chip component 10A and the semiconductor package 10B, the low-strength solder 31 and the high-strength solder 32 disposed on the low-strength solder 31 are melted by heating. As in the case of the reflow process in the BGA 10, the chip component 10A, and the semiconductor package 10B, the molten low-strength solder 31 and the high-strength solder 32 are mixed with each other, and the connection solder 30 in the molten state is formed. The molten connection solder 30 wets and spreads on the surface perpendicular to the electrode facing surface 12 and the wiring facing surface 23 of the tall component 10C. Thereafter, as in the case of the chip component 10A and the semiconductor package 10B, the base-shaped connection solder 30 is formed by curing.

  In the method for manufacturing the electronic device 1, the low-strength solder 31 and the high-strength solder 32 are applied in separate steps. However, this disclosure is not limited to this. For example, when the BGA 10 is electrically connected to the circuit board 20, the amount of the low-strength solder 31 is increased in advance than the amount of the high-strength solder 32, and the low-strength solder 31 is preliminarily used. Solder in which high-strength solder 32 is mixed may be used. Similarly, when the chip component 10A and the semiconductor package 10B are electrically connected to the circuit board 20, the amount of the high-strength solder 32 is increased in advance than the amount of the low-strength solder 31, and the low-strength solder 31 and the high-strength solder are preliminarily increased. Solder mixed with 32 may be used. Similarly, when electrically connecting the tall component 10C to the circuit board 20, the amount of the low-strength solder 31 is increased in advance from the amount of the high-strength solder 32, and the low-strength solder 31 and the high-strength solder 32 are previously added. Mixed solder may be used.

  In the present embodiment, as an example, an application process of applying a predetermined amount of low-strength solder 31 is employed. However, the present invention is not limited to this, and the amount of low-strength solder 31 that is larger than the high-strength solder 32 applied in the placement step may be applied on the first land 220 in the application step. Similarly, the low-strength solder 31 having a smaller amount than the high-strength solder 32 applied in the arranging step may be applied on the second land 220A and the third land 220B in the applying step. Similarly, the low-strength solder 31 having a smaller amount than the high-strength solder 32 applied in the arranging step may be applied on the fourth land 220C in the applying step. Thereafter, a predetermined amount of high-strength solder 32 may be applied in the arranging step.

(Operational effect of this embodiment)
According to this embodiment, by using the connection solder 30 in which the ratio of the low-strength solder 31 and the high-strength solder 32 is adjusted according to the type of electronic component, the device functions normally compared to the conventional electronic device. You can extend the period.

  More specifically, the connection solder 30 that electrically connects the BGA 10 and the circuit board 20 has a ball shape. In the ball shape, the cross-sectional area in a cross section parallel to the mounting surface 21 of the connection solder 30 decreases from the center of the connection solder 30 toward the electrode facing surface 12 and the wiring facing surface 23. That is, the angle formed by the surface of the connection solder 30 and the electrode facing surface 12 is an acute angle. For this reason, it is assumed that cracks are likely to occur on the side of the circuit board 20 due to shear stress generated by a large change in the outside air temperature. Therefore, in order to disperse the stress to the connection solder 30 and alleviate the concentration of the shear stress on the circuit board 20, the low-strength solder 31 is included in the connection solder 30 that electrically connects the BGA 10 and the circuit board 20. More than the high-strength solder 32 is contained. Since the tensile strength of the low-strength solder 31 is smaller than the tensile strength of the high-strength solder 32, the shear stress is easily dispersed in the connection solder 30. Therefore, the connection reliability of the ball-shaped connection solder 30 that electrically connects the BGA 10 and the circuit board 20 can be enhanced even in an environment where the outside air temperature changes greatly.

  The connection solder 30 that electrically connects the chip component 10A and the semiconductor package 10B to the circuit board 20 has a base shape. In the base shape, the cross-sectional area in a cross section parallel to the mounting surface 21 of the connection solder 30 increases from the electrode facing surface 12 toward the wiring facing surface 23. That is, the angle formed by the surface of the connection solder 30 and the electrode facing surface 12 is an obtuse angle. For this reason, it is assumed that the shear stress generated when the outside air temperature greatly changes is less likely to be applied to the circuit board 20 side and concentrated on the connection solder 30. Therefore, in order to ensure durability against concentrated shear stress, the high-strength solder 32 is higher than the low-strength solder 31 in the connection solder 30 that electrically connects the chip component 10 </ b> A and the semiconductor package 10 </ b> B and the circuit board 20. Many are also included. Since the tensile strength of the high-strength solder 32 is greater than the tensile strength of the low-strength solder 31, the connection solder 30 can ensure a sufficient strength against shear stress. Therefore, the connection reliability of the bottom-shaped connection solder 30 that electrically connects the chip component 10 </ b> A and the semiconductor package 10 </ b> B and the circuit board 20 can be improved even in an environment in which the outside air temperature changes greatly.

  As described above, by using the connection solder 30 mixed at the above-described ratio, the period during which the electronic device 1 functions normally can be extended as compared with the conventional electronic device using a single type of solder. .

  The connection solder 30 that electrically connects the tall component 10C and the circuit board 20 has a base shape. Therefore, since it is assumed that the above-described shear stress is concentrated on the connection solder 30, the connection solder 30 should contain more high-strength solder 32 than low-strength solder 31. However, when the electronic device 1 falls, an impact due to the drop is applied to all electronic components. Since the tall component 10C is taller than the BGA 10, the chip component 10A, and the semiconductor package 10B, the tall component 10C is more susceptible to a drop impact than other electronic components. Then, it is assumed that the influence of the drop impact is concentrated on the boundary surface between the connection solder 30 and the wiring facing surface 23.

  Therefore, in order to mitigate the concentration of the drop impact on the boundary surface between the connection solder 30 and the wiring facing surface 23, the connection between the tall component 10C and the circuit board 20 depends on the shape of the connection solder 30. The low-strength solder 31 is contained more than the high-strength solder 32. Therefore, the force can be dispersed in the connection solder 30 as compared with the connection solder 30 containing only the high-strength solder 32. Therefore, it is possible to reduce the influence of the drop impact while securing a sufficient strength against the shear stress.

  Moreover, according to the manufacturing method of this embodiment, the connection solder 30 in which the ratio of applying the low-strength solder 31 and the high-strength solder 32 is adjusted according to the type of the electronic component is formed, whereby the electronic device 1 of the present embodiment. Can be manufactured.

  More specifically, when the BGA 10 is connected to the circuit board 20, the BGA 10 and a smaller amount of the high strength solder 32 than the low strength solder 31 are arranged on the low strength solder 31 in the arrangement step. Thereafter, through a reflow process, the connection solder 30 including the low-strength solder 31 more than the high-strength solder 32 is formed.

  Further, when the chip component 10A and the semiconductor package 10B are connected to the circuit board 20, the chip component 10A, the semiconductor package 10B, and the high-strength of a larger amount than the low-strength solder 31 are disposed on the low-strength solder 31 in the placement process. Solder 32 is disposed. Thereafter, through a reflow process, the connection solder 30 including the high-strength solder 32 more than the low-strength solder 31 is formed.

  Furthermore, when connecting the tall component 10 </ b> C to the circuit board 20, the tall component 10 </ b> C and the high-strength solder 32 having a smaller amount than the low-strength solder 31 are disposed on the low-strength solder 31 in the arranging step. Thereafter, through a reflow process, as in the case of the BGA 10, the connection solder 30 including the low-strength solder 31 more than the high-strength solder 32 is formed.

  Therefore, the electronic device 1 according to this embodiment is manufactured using the connection solder 30 in which the ratio of the low-strength solder 31 and the high-strength solder 32 is adjusted according to the type of each electronic component connected to the circuit board 20. be able to. Note that the manufacturing method in which the high-strength solder 32 is applied instead of the low-strength solder 31 in the application step and the low-strength solder 31 is arranged in the arrangement step has the same effects as described above.

  The low-strength solder 31 may be a paste containing a flux. The low-strength solder 31 including the flux has higher viscosity than the low-strength solder 31 not including the flux. Therefore, in the placement step, when placing the chip component 10A, the semiconductor package 10B, and the electrode 11 of the tall component 10C in contact with part of the low-strength solder 31, the chip component 10A, the semiconductor package 10B, and the tall component. 10C can be stably arranged. That is, in the placement step, when the chip component 10 </ b> A or the like is placed on the low-strength solder 31, the chip component 10 </ b> A can be prevented from sliding off from the low-strength solder 31. Similarly, when the high-strength solder 32 is applied on the land in the application process, the chip component 10A and the semiconductor package are placed on the high-strength solder 32 in the arrangement process by including the flux in the high-strength solder 32. 10B and the tall component 10C can be stably arranged.

  DESCRIPTION OF SYMBOLS 1 ... Electronic device, 10 ... BGA, 10A ... Chip component, 10B ... Semiconductor package, 10C ... Tall component, 11 ... Electrode, 12 ... Electrode facing surface, 20 ... Circuit board, 21 ... Mounting surface, 22 ... Wiring, 30 ... Connection solder, 31 ... Low-strength solder, 32 ... High-strength solder

Claims (7)

At least two kinds of electronic components having an electrode (11);
A circuit board (20) having wiring (22) on a mounting surface (21) which is a surface on which the electronic component is mounted;
A connection solder (30) for electrically and mechanically connecting the electronic component and the circuit board;
At least part of the connection solder is an electrode facing surface (12) which is a surface facing the mounting surface of the electrode, and wiring facing is a surface where a part of the wiring is facing the electrode facing surface. Between the surface (23) and
The electronic component includes a first component (10) connected to the circuit board with the ball-shaped connection solder and a second component (10A, 10B) connected to the circuit board with the bottom-shaped connection solder. ), And
The connection solder includes a low strength solder (31) having a predetermined tensile strength and a high strength solder (32) having a higher tensile strength than the low strength solder,
The first component is connected to the circuit board with the connection solder in which the low-strength solder is more than the high-strength solder,
The electronic device in which the second component is connected to the circuit board with the connection solder in which the high-strength solder is more than the low-strength solder. The electronic component includes a third component (10C) in which the height from the mounting surface of the electronic component is a component height, and the component height is higher than the first component and the second component,
2. The electronic device according to claim 1, wherein the third component includes more low-strength solder than the high-strength solder and is connected to the circuit board with the connection solder regardless of the shape of the connection solder. The first component has the electrode only on the surface facing the mounting surface,
The electronic device according to claim 1, wherein the second component has the electrode on at least a surface that does not face the mounting surface.   The electronic device according to claim 1, wherein the connection solder contains a flux. At least two kinds of electronic components having an electrode (11);
A circuit board (20) having wiring (22) on a mounting surface (21) which is a surface on which the electronic component is mounted;
A connection solder (30) for electrically and mechanically connecting the electronic component and the circuit board;
At least part of the connection solder is an electrode facing surface (12) which is a surface facing the mounting surface of the electrode, and wiring facing is a surface where a part of the wiring is facing the electrode facing surface. Between the surface (23) and
The electronic component includes a first component (10) connected to the circuit board with the ball-shaped connection solder and a second component (10A, 10B) connected to the circuit board with the bottom-shaped connection solder. ), And
The connection solder includes a low strength solder (31) having a predetermined tensile strength and a high strength solder (32) having a higher tensile strength than the low strength solder,
The first component is connected to the circuit board with the connection solder in which the low-strength solder is more than the high-strength solder,
The second component is a manufacturing method of an electronic device connected to the circuit board with the connection solder in which the high-strength solder is more than the low-strength solder,
One of the low-strength solder and the high-strength solder is applied onto the wiring,
On the one solder, the other solder is arranged so that the first component and the low-strength solder are more than the high-strength solder,
On the one solder, arrange the other solder so that the second component and the high-strength solder are more than the low-strength solder,
A method of manufacturing an electronic device for electrically connecting the first component, the second component, and the circuit board by reflowing the one solder and the other solder to form the connection solder. The electronic component includes a third component (10C) in which the height from the mounting surface of the electronic component is a component height, and the component height is higher than the first component and the second component,
The third component is a method of manufacturing an electronic device in which the low-strength solder is more than the high-strength solder and is connected to the circuit board with the connection solder regardless of the shape of the connection solder,
On the one solder, arrange the other solder so that the third component and the low-strength solder are more than the high-strength solder,
The method for manufacturing an electronic device according to claim 5, wherein the third component and the circuit board are electrically connected by reflowing the one solder and the other solder to form the connection solder. Apply one solder containing flux on the wiring,
Arranged so that a part of the solder containing the flux is in contact with the electrodes of the second part and the third part,
The method of manufacturing an electronic device according to claim 6, wherein the other solder is applied to a portion other than the portion covered with the electrode of the second component and the third component on the one solder including the flux.

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