JP6538513B2 - Semiconductor power module and moving body - Google Patents

Description

  The present invention relates to a semiconductor power module and a moving body in which a semiconductor element and a lead are connected to an insulating substrate, and more particularly to a semiconductor power module and a moving body in which a lead is connected using ultrasonic connection.

  The semiconductor power module has a structure in which a wiring pattern made of copper, aluminum or the like is formed on an insulating substrate made of ceramic or the like, and the insulating substrate on which a plurality of semiconductor elements are mounted is housed in the module. In such a semiconductor power module, wire bonding is used for connection between electrodes and wiring patterns of the semiconductor elements, between wiring patterns, between wiring patterns and leads, and a plurality of wires are connected in parallel to flow a large current. Bonding method is used.

  In recent years, a method using a plate-like lead which can make the connection occupied area smaller than the area at the time of wire bonding has been devised from the demand for miniaturization of the semiconductor power module. As a method of connecting plate-like leads, there is a method using solder or ultrasonic connection.

  The ultrasonic connection is a method of removing an oxide film on a metal surface by giving two metals an amplitude and a load with an ultrasonic tool for a certain period of time and rubbing them, and connecting new surfaces to each other by solid phase diffusion. Although the thickness and the material of the insulating substrate and the wiring pattern are different, the insulating substrate and the wiring pattern may be damaged if the load, amplitude and time are not set properly.

  Japanese Patent Application Laid-Open No. 2011-61105 (Patent Document 1) as a technique for preventing damage to a wiring pattern and expanding a connection margin, and connecting a plate-like lead and a wiring pattern on an insulating substrate using ultrasonic connection technology. ). This publication describes a structure in which a coating layer is formed on a wiring pattern disposed on an insulating substrate. Furthermore, in this publication, a coating layer harder than the pad and the lead terminal is formed on the metal base and the pad on the insulating film. At the time of ultrasonic connection, the coating is performed by applying ultrasonic waves using an ultrasonic tool. The layers are broken, and the lead terminals on both sides of the coating layer and the pads are directly connected by plastic flow (see abstract). The coating layer is formed of a harder material than the leads and the wiring pattern, and it is described that Cr, Fe, Mo, Ni, Pt, Ta, V, W, etc. are suitable. In addition, since it is the end of the lead that breaks the wiring pattern, it is described that it is necessary to provide a coating layer at the end of the lead and its periphery and to make it thinner so as not to become an obstacle to bonding. .

JP, 2011-61105, A

  12 and 13 show the structure examined by the inventor of the present invention, and FIG. 12 (a) connects the wiring pattern 3 and the lead 5 on the ceramic insulating substrate 2 by ultrasonic connection. It is a schematic diagram of a result (connection state) when there is damage to the insulated substrate 2. FIG. As a survey method, the leads 5 and the wiring pattern 3 were removed by etching with aqua regia, and it was judged by confirming the presence or absence of damage of the Ti film (thickness 1 μm or less) remaining on the insulating substrate. As a result, a damaged portion S was observed at the lower portion of the portion where the lead is joined to the bent corner portion (bent portion).

  That is, it has been found that the damage S is formed on the insulating substrate 2 under the bent portion 5d of the lead 5 when the lead 5 and the wiring pattern 3 are ultrasonically connected by the study of the inventor of the present application. Here, the reason why the damage S is formed in the lower part of the bent portion 5 d of the lead 5 at the time of the ultrasonic connection of the lead 5 will be described.

  When each lead 5 is bent and formed by a punching die, in the case of the lead 5, as shown in FIG. 13B, the aspect ratio is small in the cross-sectional shape of the plate material (lead 5) 42. It has a fan-like shape, and as shown in part K, the central portion has a projecting (projecting) shape.

  As a result, as shown in FIG. 12A, the pressure from the central part of the lead 5 is applied to the lower part of the bent part 5d of the lead 5 at the time of the ultrasonic wave application to the lead 5. As a result, the damage S is formed. Ru.

  In addition, two methods are considered as a method with a large effect of preventing the damage to the insulating substrate. One is a method of reducing the damage to the insulating substrate by weakening the connection state by reducing the load and amplitude of the connection conditions or shortening the connection time. However, in this method, it is expected that the connection strength is reduced and the long-term reliability is deteriorated, and the connection area is reduced, and the current value which can be flowed is limited, and the capacity can not be increased. Another method is a method described in Patent Document 1, in which a wiring layer is provided with a lead and a coating layer made of a material harder than the wiring pattern at a thinly joined portion with a lead end. However, although this method is effective in preventing damage to the wiring pattern immediately below the lead end by the structure of the insulating film and the wiring pattern on the metal base, the structure of the ceramic substrate and the wiring pattern used in the high breakdown voltage power module There is no effect on the damage to the ceramic substrate immediately below the bent corner of the lead.

  The object of the present invention is to prevent damage to the insulating substrate by widening the connection condition margin when connecting the wiring pattern on the insulating substrate and the leads by ultrasonic connection in the semiconductor power module and the movable body. It is about providing technology.

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

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

  A semiconductor power module according to the present invention includes an insulating substrate on which a wiring pattern is formed, a semiconductor element mounted on the insulating substrate via a connecting member, and a connected portion connected to the wiring pattern, One end in the extending direction of the portion is an end portion, and the other is a bent portion. Furthermore, the connected portion and the wiring pattern are connected by ultrasonic connection, and the connected portion includes a first area located on the end side and a second area located on the bent side. The first region is connected to the wiring pattern, and the second region is connected to the wiring pattern through a metal layer formed of a Ni layer or a Ni alloy layer.

  A mobile according to the present invention includes a semiconductor power module, and the semiconductor power module includes an insulating substrate on which a wiring pattern is formed, and a semiconductor element mounted on the insulating substrate through a connection member. And a lead portion connected to the wiring pattern, wherein one of the connected portions in the extending direction is an end portion, and the other is a bent portion. Furthermore, the connected portion and the wiring pattern are connected by ultrasonic connection, and the connected portion includes a first area located on the end side and a second area located on the bent side. The first region is connected to the wiring pattern, and the second region is connected to the wiring pattern through a metal layer formed of a Ni layer or a Ni alloy layer.

  The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

  In the semiconductor power module and the movable body, when ultrasonically connecting the wiring pattern on the insulating substrate and the lead having the bent portion, damage can be alleviated and damage to the insulating substrate immediately below can be suppressed. Further, the tip end side of the lead can be easily connected since it is directly connected to the wiring pattern, and the margin of the connection condition can be easily secured.

It is a perspective view which shows an example of the structure of the semiconductor power module of embodiment of this invention. It is a perspective view which shows an example of the structure which removed the lid | cover of the semiconductor power module shown in FIG. It is an expanded view of the semiconductor power module shown in FIG. It is a top view which shows an example of the structure which remove | eliminated the lid | cover and lead of the semiconductor power module shown in FIG. It is a top view which shows an example of the structure which removed the lid | cover of the semiconductor power module shown in FIG. It is sectional drawing which shows an example of the structure cut | disconnected along the AA shown in FIG. It is an expanded fragmentary sectional view which shows the lead connection part of the semiconductor power module shown in FIG. It is a top view which shows an example of the structure which removed the lead in FIG. It is an enlarged fragmentary sectional view which shows an example of the connection structure of the lead | read | reed in the lead connection part of the semiconductor power module shown in FIG. 1, and a wiring pattern. FIG. 10 is an enlarged partial cross-sectional view showing a structure of a portion A shown in FIG. 9; FIG. 10 is an enlarged partial cross-sectional view showing a structure of a portion B shown in FIG. 9; (A), (b) is a fragmentary sectional view and sectional drawing which show the lead connection structure in the semiconductor power module of the comparative example which the present inventor compared and examined. (A), (b), (c) is a conceptual diagram and sectional drawing which show the stress which generate | occur | produces in the bending part of the lead of the comparative example shown in FIG. FIG. 10 is an enlarged partial cross-sectional view showing a lead connection portion of the semiconductor power module of Modification Example 1; It is a top view which shows an example of the structure which removed the lead in FIG. FIG. 18 is a cross-sectional view showing a structure before connecting a lead of Modification 2; FIG. 18 is a cross-sectional view showing a structure after connecting a lead of Modification 2; It is a schematic diagram which shows the example of mounting of the semiconductor power module shown in FIG. 1 (modification 3, railway vehicle). It is a top view which shows the example of mounting shown in FIG. It is a schematic diagram which shows the example of mounting (the modified example 4, a motor vehicle) of the semiconductor power module shown in FIG. It is a top view which shows the example of mounting shown in FIG.

  In the following embodiments, the description of the same or similar parts will not be repeated in principle unless particularly required.

  Furthermore, in the following embodiments, when it is necessary for the sake of convenience, it will be described divided into a plurality of sections or embodiments, but unless otherwise specified, they are not unrelated to each other, one is The other part or all of the variations, the details, the supplementary explanation, etc. are in a relation.

  Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), it is particularly pronounced and clearly limited to a specific number in principle. Except for the specific number, it is not limited to the specific number but 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 essential except in the case where they are particularly clearly shown and where they are considered to be obviously essential in principle. Needless to say.

  Further, in the following embodiments, when it is referred to as "consisting of A", "consisting of A", "having A", and "including A" with respect to components etc. It goes without saying that the other elements are not excluded except in the case where the Similarly, in the following embodiments, when referring to the shapes, positional relationships and the like of components etc., the shapes thereof are substantially the same unless particularly clearly stated and where it is apparently clearly not so in principle. It is assumed that it includes things that are similar or similar to etc. The same applies to the above numerical values and ranges.

  Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In all the drawings for describing the embodiments, members having the same functions are denoted by the same reference numerals, and the repetitive description thereof will be omitted. Moreover, hatching may be attached even if it is a plan view in order to make a drawing intelligible.

  First, a common basic structure of the semiconductor power module of the present embodiment will be described.

  FIG. 1 is a perspective view showing an example of the structure of a semiconductor power module according to an embodiment of the present invention, FIG. 2 is a perspective view showing an example of the structure of the semiconductor power module shown in FIG. FIG. 7 is a development view of the semiconductor power module shown in FIG. 4 is a plan view showing an example of the structure in which the lid and the lead of the semiconductor power module shown in FIG. 1 are removed, and FIG. 5 is a plan view showing an example of the structure in which the lid of the semiconductor power module shown in FIG. FIG. 6 is a cross-sectional view showing an example of a structure cut along line A-A shown in FIG.

  The semiconductor power module 15 of the present embodiment shown in FIGS. 1 and 2 is, for example, a high withstand voltage power module mounted on an inverter or the like of a railway vehicle or a car. In this case, since a large current flows, the semiconductor module (semiconductor chip) 4 generates a large amount of heat.

  First, the entire configuration of the semiconductor power module 15 will be described. As shown in FIG. 1, the base plate 1, the case 7 which is a side wall attached along the outer periphery of the base plate 1, and the opening portion of the case 7 It has a lid 12 to be closed, and external terminals 13a, 13b and 13c exposed to the outside of the lid 12. The three external terminals 13a, 13b and 13c are disposed in the vicinity of the end portions on both sides in the longitudinal direction of the case 7 so as to be dispersed into two and one.

  Next, the internal structure of the semiconductor power module 15 will be described with reference to FIGS. 2 to 6. The insulating substrate 2 on which the wiring pattern 3 is formed, and the connecting member (solder) 16 (see FIG. 6) A semiconductor element 4 mounted via the semiconductor device 1 and a plurality of plate-like parts 10 which are stacked in a state of being insulated from each other covering the upper side of the semiconductor element 4 are provided.

  Furthermore, as shown in FIG. 3, connection leads (lead portions) 5 extending toward the insulating substrate 2 are formed in each of the plurality of plate-like portions 10.

  A plurality of connection leads 5 are provided, and these leads 5 are electrically connected to the R portion of the wiring pattern 3 of the insulating substrate 2 shown in FIG.

  Further, as shown in FIG. 6, the insulating substrate 2 is mounted on the base plate 1 via the connection member 16 such as solder, and the wiring patterns 3 are formed on the front and back surfaces of the insulating substrate 2. . Further, on the wiring pattern 3, a lead 5 for connection extending from the plate-like portion 10 is disposed and electrically connected to the wiring pattern 3. The connection of the leads 5 and the wiring pattern 3 is performed by ultrasonic connection.

  Further, the base plate 1 and the case 7 are fixed by screws, an adhesive or the like. The case 7 and the external terminals 13a, 13b and 13c are provided with screw holes 8 used when connecting to an external device (not shown), and further, one of the longitudinal directions of the case 7 shown in FIG. A plurality of control leads 9 are provided on the inner wall of the side. Further, each of the plurality of control leads 9 is formed in an L shape, and is embedded and fixed so that a part is exposed to the inner wall of the case 7.

  And, as shown in FIG. 4 and FIG. 5, a part of these control leads 9 are electrically connected to the wiring pattern 3 through the wires 6 which are respectively fine metal wires. The wire 6 is made of, for example, aluminum, copper or gold.

  Further, in the semiconductor power module 15, as shown in the developed view of FIG. 3 (the case 7, the lid 12 and the wire 6 are omitted to make the explanation easy to understand), the three plate portions 10a, 10b, 10c are laminated, and the respective plate-like parts 10 are laminated so as to be insulated from each other. Here, the thin plate-like insulating member 14 is interposed between the plate-like parts 10 to be stacked, whereby insulation between the plate-like parts 10 is performed. Further, in each plate-like portion 10, a plurality of leads 5 which are formed to be bent in a direction intersecting the plate-like portion itself are formed.

  As described above, the three stacked plate-like parts 10 are in a state where the adjacent plate-like parts in the thickness direction are insulated. That is, as shown in FIG. 3, the plate-like insulating member 14 is interposed between the plate-like parts, whereby each plate-like part 10 has a certain distance or more to secure the withstand voltage. Are placed (a certain distance apart).

  Further, in the semiconductor power module 15 of the present embodiment, in the structure shown in FIG. 4, the larger semiconductor element 4 is, for example, a Si semiconductor element such as an IGBT (Insulated Gate Bipolar Transistor). The smaller semiconductor element 4 is, for example, a Si semiconductor element such as a diode.

  Further, as shown in FIGS. 4 and 5, the semiconductor elements, the semiconductor element 4 and the wiring pattern 3, and the wiring pattern 3 and a part of the control lead 9 are electrically connected by wires 6, respectively.

  Further, as shown in FIG. 6, the insulating substrate 2 is fixed to the base plate 1 by connecting the wiring pattern 3 on the lower side (rear side) to the base plate 1 via the connection member (solder) 16. ing.

  In addition, a gel-like sealing resin (not shown) is filled in the gap in the case 7 to secure the pressure resistance between the plate-like portions and the like. Then, the inside of the case 7 is closed by the lid (for example, made of plastic) 12 shown in FIG.

  Next, details of the internal structure of the semiconductor power module 15 will be described. 7 is an enlarged partial sectional view showing the lead connection portion of the semiconductor power module shown in FIG. 1, FIG. 8 is a plan view showing an example of the structure from which the lead is removed in FIG. 7, and FIG. 9 is a semiconductor power module shown in FIG. It is an expanded fragmentary sectional view which shows an example of the junction structure of the lead | read | reed in a lead connection part, and a wiring pattern. 10 is an enlarged partial sectional view showing the structure of the part A shown in FIG. 9, and FIG. 11 is an enlarged partial sectional view showing the structure of the part B shown in FIG.

  As described above, in the lead connection portion shown in FIG. 7, the insulating substrate 2 is mounted on the base plate 1 via the connection member 16 such as solder, and the wiring patterns 3 are provided on the front and back surfaces of the insulating substrate 2. It is formed. A semiconductor element (semiconductor chip) 4 is mounted on the wiring pattern 3 via a connection member 16 as shown in FIG. Further, a lead (lead portion) 5 used for connection with the outside is also connected to the wiring pattern 3. As shown in FIGS. 7 and 8, the lead 5 is provided with a connected portion 5a connected to the wiring pattern 3, and one end of the connected portion 5a in the extending direction Q is an end portion (termination portion 5e, and the other is a bend 5d. Here, the bent portion 5d is a bent portion of the lead 5, which is a portion from one end of the bent portion to the opposite end. Therefore, the bending portion 5d is a region having a width of bending.

  As described above, in the semiconductor power module 15, the wiring pattern 3 and the connected portion 5a of the lead 5 are connected by ultrasonic connection. Further, a case 7 is mounted on an outer peripheral portion of the base plate 1 through a joining member (not shown), and a control lead 9 is provided in the case 7 so as to be partially embedded. Then, as shown in FIG. 1, the inside of the power module is protected by a lid 12 disposed on the upper surface of the case 7. Furthermore, although not shown, a gel is injected into the inside of the case 7 so that the withstand voltage can be maintained. The control lead 9, the wiring pattern 3, and the semiconductor element 4 are electrically connected by the wire 6 which is a thin metal wire.

  The base plate 1 is mainly made of aluminum, aluminum alloy, copper, copper alloy, AlSiC or the like having good thermal conductivity from the viewpoint of heat dissipation, and is formed of these materials, and further, water cooling or air cooling from the back side. It is cooled by The material of the connection member 16 is solder, sintered silver, sintered copper or the like. The material of the insulating substrate 2 is mainly alumina, AlN (aluminum nitride), SiN (silicon nitride) or the like, and the material of the wiring pattern 3 is mainly Cu (copper), Cu (copper) alloy, aluminum or the like.

  Further, although the connection between the insulating substrate 2 and the wiring pattern 3 differs depending on the combination of materials, a direct connection or a method using a brazing material is mainly used. In the case of high withstand voltage, the thickness of the insulating substrate 2 is, for example, 0.2 to 0.6 mm, and the thickness of the wiring pattern 3 is 0.1 to 0.6 mm.

  The material of the semiconductor element 4 is Si, SiC, GaN or the like. Furthermore, the material of the case 7 and the lid 12 is often resin because of the complexity of the shape. The material of the control lead 9 is an alloy of iron or copper because it needs to be thin and strong. The material of the leads 5 is a copper (Cu), Cu (copper) alloy, aluminum, an aluminum alloy, a clad material of copper and aluminum, or the like, which has a high heat conductivity, and a large electric conductivity, since a large current flows.

  The material of each member is determined from the viewpoints of application, heat dissipation, electrical characteristics, cost, long-term reliability and the like, and is not limited to the above-mentioned ones.

  Next, features of the semiconductor power module 15 according to the present embodiment will be described with reference to the drawings.

  As shown in FIG. 7, the insulating substrate 2 is mounted on the base plate 1 via the connection member 16, and the wiring patterns 3 are provided on the front and back surfaces of the insulating substrate 2. A Ni layer 11 (metal layer) is provided on a part of the wiring pattern 3, and the lead 5 is connected to the wiring pattern 3 by ultrasonic connection. As shown in FIGS. 7 and 8, in the connected portion (connection surface) 5a of the wiring pattern 3 and the lead 5, the end 5e side (tip end side) of the lead 5 is directly connected to the wiring pattern 3, On the other hand, the side of the bent portion 5 d (corner side) where the lead 5 is bent is connected via the Ni layer 11.

  Specifically, as shown in FIG. 7, the semiconductor power module 15 is provided with a plurality of leads 5 provided with connected parts 5 a connected to the wiring pattern 3. Each of the connected parts 5a of the leads 5 has an end (end part) 5e on the tip end side of the connected part 5a and a bending part 5d located on the opposite side. The bent portion 5 d of the lead 5 is a portion obtained by bending the lead 5 in a substantially horizontal direction from the substantially vertical direction of the semiconductor power module 15 so that the lead 5 can be connected to the wiring pattern 3 of the insulating substrate 2. Each of the leads 5 in the semiconductor power module 15 is formed by punching.

  Furthermore, each connected portion 5a is a portion electrically connected to the wiring pattern 3 of the insulating substrate 2 in the lead 5, but each connected portion 5a is a first region located on the end 5e side It has 5b and the 2nd field 5c located in the bending part 5d side. The first region 5 b in the connected portion 5 a is directly connected to the wiring pattern 3, and the second region 5 c is connected to the wiring pattern 3 via the Ni layer 11. That is, the first region 5b is directly connected to the wiring pattern 3 without the intervention of an alloy layer or the like.

  Thus, in the semiconductor power module 15 of the present embodiment, the Ni layer 11 is interposed between the second region 5 c located on the side of the bent portion 5 d of the connected portion 5 a of the lead 5 with the wiring pattern 3. Therefore, it is possible to relieve that pressure is applied to the insulating substrate 2 below the bending portion 5d at the time of applying an ultrasonic wave when performing lead connection. That is, the Ni layer 11 serves as a barrier layer, and the pressure applied to the insulating substrate 2 can be relieved. As a result, formation of a damaged portion S (see FIG. 12 described later) in the insulating substrate 2 can be reduced.

  On the other hand, the first region 5b on the side of the end 5e which is the tip end side of the connected portion 5a of the lead 5 is directly connected to the wiring pattern 3 and secures the electrical connection between the lead 5 and the insulating substrate 2 doing. Then, as shown in FIG. 8, the boundary between the first region 5 b and the second region 5 c in the connected portion 5 a is substantially half of the extending direction Q in the connected portion 5 a of the lead 5. That is, the sizes of the first area 5b and the second area 5c in plan view are substantially equal. In the first area 5b and the second area 5c, either one may be slightly larger to such an extent that the respective functions are not impaired.

  In addition, the Ni layer 11 may be a Ni alloy layer (metal layer).

  Here, the reason why the damaged portion S is formed on the insulating substrate 2 under the bent portion 5 d of the lead 5 will be described in detail with reference to FIGS. 12 and 13. 12 (a) and 12 (b) are partial cross-sectional views and cross-sectional views showing a lead connection structure in a semiconductor power module of a comparative example for which the inventors of the present invention compared and studied; 12] is a conceptual view and a cross-sectional view showing a stress generated at a bent portion of the lead of the comparative example shown in FIG.

  As shown in FIG. 12B, the manufacturing method of the terminal 40 includes etching, punching with a die, wire cutting and the like, but in mass production, since it is necessary to reduce the cost, it is generally manufactured by punching There are many things to do. FIG. 12 (b) shows a cross section of the terminal 40 manufactured by punching. In the terminal 40, dripping portions I and J are formed on the surface (H portion) to be cut first, and a sharp edge portion 41 is formed on the end portion on the surface (G portion) to be cut last Ru.

  Therefore, in order to achieve good connection of the connection portion of the terminal 40, the terminal 40 can be moved smoothly by using the surface (H portion) on the side of the dripping portion as the connection surface, and the connection can be stabilized. it can.

  However, as shown in FIG. 12A, pressure is applied to the insulating substrate 2 below the bent portion 5d in the connected portion 5a of the lead 5 when ultrasonic waves are applied when the lead is connected. This phenomenon will be described in detail with reference to FIG. The bending of the lead using the punching die will be described by replacing it with the bending of the plate 42 shown in FIG. 13 (a). When the plate 42 is bent as shown in FIG. 13A, a force of compression 45 is applied to the upper side in the longitudinal direction 43 and a force of pull 46 is applied to the lower side. A force of pulling 46 is applied to the upper side in the width direction 44 and a force of compression 45 is applied to the lower side. Then, a neutral plane 47 of distortion occurs on the half surface in the thickness direction.

  As shown in FIG. 13B, when the aspect ratio of the cross-sectional shape of the plate member 42 is small, the entire plate member 42 is deformed into a fan-like shape in the cross section of the plate member 42 bent as described above. The vicinity (K part) protrudes (projects).

  On the other hand, as shown in FIG. 13C, in the cross-sectional shape of the plate member 42, when the aspect ratio is large, the resistance of the force against the bending in the width direction 44 is large, so the central portion (L portion) is deformed Without deformation, only the end (M part) side is deformed. The cross-sectional shape of the lead 5 is close to the cross-sectional shape of FIG. 13B, so the aspect ratio is small and it deforms like a fan. That is, the central portion protrudes (projects).

  Therefore, when ultrasonically connecting using the lead 5 deformed in this way, as shown in FIG. 12A, when applying the ultrasonic wave to the insulating substrate 2 below the bending portion 5d in the connected portion 5a of the lead 5 Pressure is applied, and as a result, a damaged portion S is formed in the insulating substrate 2.

  Therefore, in the semiconductor power module 15 shown in FIG. 1 of the present embodiment, as shown in FIGS. 7 and 8, the wiring pattern is formed in the second area 5c located on the bent portion 5d side of the connected portion 5a of the lead 5. A Ni layer 11 is interposed between them and 3. As a result, application of pressure to the insulating substrate 2 below the bending portion 5d can be alleviated when applying an ultrasonic wave at the time of lead connection, and as a result, the insulating substrate 2 can be formed as shown in FIG. It can reduce that the damage part S as shown is formed.

  The reason why the Ni layer 11 or the Ni alloy layer is adopted as the layer formed under the bent portion 5d of the lead 5 is based on the cost and the connection results. That is, among the materials used as the barrier layer, the Ni layer 11 or the Ni alloy layer is suitable because the cost is low and the connection reliability is proven.

  Further, when an AlN (aluminum nitride) substrate is employed as the insulating substrate 2, the aluminum nitride substrate has small bending strength and easily forms a damaged portion S as shown in FIG. By forming the Ni layer 11 or the Ni alloy layer in the lower part of 5 d, it is possible to suppress the formation of the damaged portion S in the aluminum nitride substrate.

  Moreover, the heat dissipation can be improved by the leads 5 and the wiring pattern 3 of the insulating substrate 2 being formed of Cu (copper) or Cu (copper) alloy. This is because, in the semiconductor power module 15 of the present embodiment, Joule heat is generated when current flows to the terminal (lead 5), but this Joule heat can be diffused to the insulating substrate 2 and the plate-like portion 10, The heat dissipation of the semiconductor power module 15 can be improved. Furthermore, the electrical characteristics of the semiconductor power module 15 can be improved by forming the leads 5 and the wiring pattern 3 of the insulating substrate 2 from Cu (copper) or Cu (copper) alloy.

  Next, another characteristic portion of the connection portion of the lead 5 of the semiconductor power module 15 will be described.

  As shown in FIGS. 7 and 8, a Ni layer 11 is provided on a part of the wiring pattern 3. The Ni layer 11 has a size that extends to about half the extending direction Q of the connected portion 5a of the lead 5 on the side of the bent portion 5d (corner side) of the lead 5. The size should be considered. Specifically, the Ni layer 11 is exposed around the second region 5c of the connected portion 5a in a plan view. That is, the Ni layer 11 is formed to be exposed around the connected portion 5a in both the width direction P and the extending direction Q of the connected portion 5a, in other words, the Ni layer 11 is connected It is formed larger than the second region 5c of the portion 5a. Thereby, when connecting the leads 5 by ultrasonic waves, the margin can be increased with respect to the connection position with the Ni layer 11.

  The thickness of the Ni layer 11 (the same applies to the Ni alloy layer) is preferably about 2 to 6 μm. This is because when the Ni layer 11 is too thin, it can not serve as a barrier layer, and when it is too thick, the material cost becomes high. For example, in the case of the Ni layer 11, when the thickness is less than 1.5 μm, the formation of the Ni layer 11 becomes difficult. The formation method of the Ni layer 11 is, for example, a plating deposition method, a jab dipping method, an electrolytic plating method, an electroless plating method, or the like.

  Next, experimental results of the semiconductor power module 15 according to the present embodiment will be described with reference to FIGS. FIGS. 9 and 10 illustrate SEM images of the cross section in which the leads 5 and the wiring pattern 3 are connected. The material of the insulating substrate 2 is AlN (aluminum nitride), and the material of the wiring pattern 3 and the leads 5 is Cu (copper). Although not shown in FIGS. 9 and 10 because the SEM image is illustrated, the Ni layer 11 (thickness) is connected to a portion connected to the corner portion (bent portion 5d) of the lead 5 of the wiring pattern 3 2 to 6 μm). 10 is an enlarged view of a portion A of FIG. 9, and FIG. 11 is an enlarged view of a portion B of FIG. As a result of FIG. 10, it could be confirmed that the insulating substrate 2 was not damaged by the Ni layer 11. Further, in FIG. 11, the region inside the dotted line is the connection region 18 of the lead 5 and the wiring pattern 3, and the Ni layer 11 existing before the connection in this connection region 18 was broken at the time of connection, It could be confirmed that a small piece of Ni piece 20 was present.

  As described above, by interposing the Ni layer 11 or the Ni alloy layer between the second region 5c on the bent portion 5d side of the connection portion 5a of the lead 5 and the wiring pattern 3, damage to the insulating substrate 2 is suppressed. be able to. Further, since the first region 5 b of the connected portion 5 a of the lead 5 is directly connected to the wiring pattern 3, the decrease in connection strength can be prevented, and the margin of the connection condition can be expanded.

  That is, in the semiconductor power module 15, the Ni layer 11 or the Ni alloy layer is provided under the bent portion 5 d of the lead 5, thereby superimposing the wiring pattern 3 on the insulating substrate 2 and the lead 5 having the bent portion 5 d. It is possible to alleviate the damage given to the insulating substrate 2 at the time of sound wave connection. Therefore, damage to the insulating substrate 2 immediately below the bent portion 5d of the lead 5 can be suppressed. Further, since the tip end side (end 5e side) of the connected portion 5a of the lead 5 is directly connected to the wiring pattern 3, it can be easily connected, and the margin of the connection condition can be easily secured.

(Modification 1)
FIG. 14 is an enlarged partial sectional view showing the lead connection portion of the semiconductor power module of the first modification, and FIG. 15 is a plan view showing an example of the structure from which the lead is removed in FIG.

  In the structure of the first modification shown in FIG. 14, the insulating substrate 2 is mounted on the base plate 1 via the connection member 16, and the wiring patterns 3 are provided on the front and back surfaces of the insulating substrate 2. A Ni layer 11 is provided on the wiring pattern 3 and there is a place where the Ni layer 11 is not applied so that the wiring pattern 3 is exposed in the portion connected to the tip end side (end 5e side) of the lead 5 . Further, the leads 5 are connected to the wiring pattern 3 by ultrasonic connection. Thereby, on the connection surface of the wiring pattern 3 and the lead 5, the tip side (end 5e side) of the lead 5 is directly connected to the wiring pattern 3, while the corner side where the lead 5 is bent ( The bent portion 5 d side is connected to the wiring pattern 3 via the Ni layer 11.

  As shown in FIG. 15, the wiring pattern 3 is provided with a Ni layer 11 over substantially the front surface except for the opening 3a. That is, the Ni layer 11 is formed so as to cover substantially the entire wiring pattern 3, and the first region 5 b of the connected portion 5 a of the lead 5 is a wiring pattern in the opening 3 a formed in the Ni layer 11. It is directly connected with 3. Further, the opening 3a is larger than the first region 5b of the connected portion 5a in plan view, and the wiring pattern 3 is exposed in the opening 3a around the first region 5b. That is, since it is necessary to consider the positional deviation between the connected portion 5 a of the lead 5 and the wiring pattern 3, the opening 3 a of the wiring pattern 3 extends in the extending direction Q of the connected portion 5 a of the lead 5. And the size is larger than that of the first region 5b of the connected portion 5a in plan view.

  The thickness of the Ni layer 11 is desirably 2 to 6 μm as in the above embodiment. Also, the Ni layer 11 may be a Ni alloy layer.

  As described above, in the connected portion 5a of the wiring pattern 3 and the lead 5, the end 5e of the lead 5 is directly connected to the wiring pattern 3, while the bent portion 5d of the connected portion 5a of the lead 5 is Since the Ni layer 11 is connected to the wiring pattern 3 through the Ni layer 11 and thereby the Ni layer 11 becomes a barrier layer, damage to the insulating substrate 2 can be suppressed as in the above embodiment. Further, since the connection portion 5a of the lead 5 and the wiring pattern 3 are directly connected in the opening 3a of the wiring pattern 3, the connection strength can be secured and the reduction in the connection strength can be prevented. Also, the margin of connection conditions can be expanded. Furthermore, the Ni layer 11 is provided over substantially the entire surface of the wiring pattern 3, and as a result, the connectivity between the semiconductor element (semiconductor chip) 4 and the wiring pattern 3 can be improved. That is, as shown in FIG. 6, since the semiconductor element 4 is connected to the wiring pattern 3 by the solder (connection member) 16, the wettability of the solder 16 can be improved by interposing the Ni layer 11. As a result, the connectivity of the semiconductor element 4 by soldering can be improved.

(Modification 2)
FIG. 16 is a cross-sectional view showing the structure of the lead of the modification 2 before connection, and FIG. 17 is a cross-sectional view of the structure of the lead of the modification 2 after connection.

  In the above embodiment and the first modification, the case where the Ni layer 11 is formed on the wiring pattern 3 of the insulating substrate 2 has been described, but in the second modification, as shown in FIG. The Ni layer 11 is formed on the side of the bent portion 5d. At this time, the Ni layer 11 is also formed on the second region 5c of the connected portion 5a and the lead portion above the bent portion 5d.

  Thus, when the lead 5 is connected to the wiring pattern 3 by ultrasonic connection, as shown in FIG. 17, a state in which a part of the Ni layer 11 remains in the lead portion above the bent portion 5d of the lead 5 Become.

  Also in the connection method of the second modification, the Ni layer 11 in the second region 5c of the connected portion 5a of the lead 5 serves as a barrier layer, so that damage to the insulating substrate 2 can be suppressed as in the above embodiment. it can. Further, since the first region 5b of the connected portion 5a of the lead 5 and the wiring pattern 3 are directly connected, it is possible to secure the connection strength and to prevent the reduction of the connection strength. Also, the margin of connection conditions can be expanded. Furthermore, by forming the Ni layer 11 on the lead 5 side in advance, the step of forming the Ni layer 11 can be omitted in the step of forming the insulating substrate 2, and the assembly of the semiconductor power module 15 can be simplified. be able to.

(Modification 3)
FIG. 18 is a schematic view showing an example of mounting of the semiconductor power module shown in FIG. 1 (Modification 3; railway vehicle), and FIG. 19 is a plan view showing an example of mounting shown in FIG.

  The third modification describes a mobile unit on which the semiconductor power module of the above-described embodiment is mounted. As an example, a power module (semiconductor power module) 19 is a current collector as shown in FIG. The case where it mounts in the inverter 23 installed in the rail vehicle (mobile body) 21 in which a certain pantograph 22 was provided is shown.

  As shown in FIG. 19, a plurality of power modules 19 are mounted on the printed circuit board 25 inside the inverter 23, and a cooling device 24 for cooling the power modules 19 is further mounted.

  The power module 19 generates a large amount of heat from the semiconductor element. Therefore, the cooling device 24 is attached so as to cool the plurality of power modules 19 and cool the inside of the inverter 23.

  The main structure of the power module 19 is the same as that of the power module 15 of the above embodiment. Therefore, as in the structure shown in FIG. 7, in the connected portion 5 a of the wiring pattern 3 and the lead 5, the end 5 e side of the lead 5 is directly connected to the wiring pattern 3, while the connected portion of the lead 5 The bent portion 5 d side of 5 a is connected to the wiring pattern 3 via the Ni layer 11. Thereby, since the Ni layer 11 becomes a barrier layer, damage to the insulating substrate 2 can be suppressed as in the above embodiment.

  Furthermore, even in the case where the temperature of the inside of the inverter 23 becomes high due to the provision of the inverter 23 on which a plurality of power modules (semiconductor power modules) 19 are mounted in the railway vehicle (moving body) 21, The reliability of the inverter 23 and the railway vehicle 21 provided with the inverter 23 can be enhanced.

(Modification 4)
FIG. 20 is a schematic view showing a mounting example (Modification 4, car) of the semiconductor power module shown in FIG. 1, and FIG. 21 is a plan view showing the mounting example shown in FIG.

  The power module (semiconductor power module) 29 of the modification 4 is an automotive power module mounted on the inverter 23 installed on the vehicle body 28 of the automobile (mobile body) 27 traveling by the tire 28a as shown in FIG. .

  As shown in FIG. 21, inside the inverter 23, a plurality of (for example, two) power modules 29 are mounted on the printed circuit board 25, and a cooling device 24 for cooling the power modules 29 is further mounted. The power module 29 generates a large amount of heat from the semiconductor element (semiconductor chip) 4. Therefore, the cooling device 24 is attached so as to cool the plurality of power modules 29 and cool the inside of the inverter 23.

  The main structure of the power module 29 is the same as that of the power module 15 of the above embodiment. Therefore, as in the structure shown in FIG. 7, in the connected portion 5 a of the wiring pattern 3 and the lead 5, the end 5 e side of the lead 5 is directly connected to the wiring pattern 3, while the connected portion of the lead 5 The bent portion 5 d side of 5 a is connected to the wiring pattern 3 via the Ni layer 11. Thereby, since the Ni layer 11 becomes a barrier layer, damage to the insulating substrate 2 can be suppressed as in the above embodiment.

  Furthermore, even in the case where the interior of the inverter 23 becomes a high temperature environment, the inverter 23 and the inverter 23 are provided also in the automobile (mobile body) 27 by providing the inverter 23 on which the plurality of power modules 29 are mounted. It is possible to enhance the reliability of the used automobile 27.

  The heat resistant temperature of the power module 29 is determined by the material of the semiconductor element 4 mounted. Although the temperature is 150 ° C. in the case of the semiconductor device made of Si and 200 ° C. in the case of the semiconductor device made of SiC, these numerical values are merely an example and can be variously changed. The heat-resistant temperature of the power module 29 required by the automobile 27 is also determined by the material of the semiconductor element 4.

  As mentioned above, although the invention made by the present inventor was concretely explained based on the embodiment of the invention, the present invention is not limited to the embodiment of the above-mentioned invention, and various changes are possible in the range which does not deviate from the summary. It goes without saying that it is possible.

  The present invention is not limited to the above-described embodiment, but includes various modifications. For example, the above-described embodiments are described in detail to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations.

  Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. . In addition, it is possible to add, delete, and replace other configurations in part of the configurations of the respective embodiments. The respective members and relative sizes described in the drawings are simplified and idealized in order to explain the present invention in an easy-to-understand manner, and the mounting becomes more complicated.

1 base plate 2 insulating substrate 3 wiring pattern 4 semiconductor element 5 lead (lead portion)
DESCRIPTION OF SYMBOLS 5a to-be-connected part 5b 1st area | region 5c 2nd area | region 5d bending part 11 Ni layer 15 power module (semiconductor power module)
16 Solder (connection member)
19 Power Module (Semiconductor Power Module)
21 Railcar (mobile)
27 Car (mobile)
29 Power Module (Semiconductor Power Module)

Claims (12)

An insulating substrate on which a wiring pattern is formed,
A semiconductor element mounted on the insulating substrate via a connection member;
A lead portion including a connected portion connected to the wiring pattern, one of the connected portions in the extending direction being an end, and the other being a bent portion;
Have
The connected portion and the wiring pattern are connected by ultrasonic connection,
The connected portion includes a first area located on the end side and a second area located on the bent side.
The first region is connected to the wiring pattern,
The second region is connected to the wiring pattern through a metal layer formed of a Ni layer or a Ni alloy layer ,
The metal layer covers the wiring pattern,
The said 1st area | region in the said to-be-connected part of the said lead part is a semiconductor power module directly connected with the said wiring pattern in the opening part formed in the said metal layer . In the semiconductor power module according to claim 1,
The semiconductor power module, wherein each of the wiring pattern and the lead portion is made of Cu or a Cu alloy. In the semiconductor power module according to claim 1,
The semiconductor power module, wherein the metal layer is exposed around the second region of the connected portion in plan view. In the semiconductor power module according to claim 1 ,
The opening is larger than the first region of the connected portion in a plan view.
The semiconductor power module in which the said wiring pattern is exposed to the said opening part around the said 1st area | region. The semiconductor power module according to any one of claims 1 to 4 .
The semiconductor power module, wherein the insulating substrate is an aluminum nitride substrate. The semiconductor power module according to any one of claims 1 to 4 .
The semiconductor power module, wherein the lead portion is a lead formed by stamping and forming. A mobile unit having a semiconductor power module,
The semiconductor power module is
An insulating substrate on which a wiring pattern is formed,
A semiconductor element mounted on the insulating substrate via a connection member;
A lead portion including a connected portion connected to the wiring pattern, one of the connected portions in the extending direction being an end, and the other being a bent portion;
Have
The connected portion and the wiring pattern are connected by ultrasonic connection,
The connected portion includes a first area located on the end side and a second area located on the bent side.
The first region is connected to the wiring pattern,
The second region is connected to the wiring pattern through a metal layer formed of a Ni layer or a Ni alloy layer ,
The metal layer covers the wiring pattern,
The first body in the connected portion of the lead portion is directly connected to the wiring pattern at an opening formed in the metal layer . In the mobile unit according to claim 7 ,
Each of the wiring pattern and the lead portion is made of Cu or a Cu alloy. In the mobile unit according to claim 7 ,
The movable body, wherein the metal layer is exposed around the second region of the connected portion in plan view. In the mobile unit according to claim 7 ,
The opening is larger than the first region of the connected portion in a plan view.
The movable body, wherein the wiring pattern is exposed at the opening around the first area. In the mobile unit according to claim 7 ,
The movable substrate is an aluminum nitride substrate as the insulating substrate. In the mobile unit according to any one of claims 7 to 11 ,
The moving body is a railway vehicle or a car.

Images