JP6569558B2 - module - Google Patents

Description

  The present invention relates to a module.

  As a technique for joining metal members together, for example, a method described in Patent Document 1 (Japanese Patent Laid-Open No. 9-270471) is known. In Patent Document 1, the metal protrusion provided on the metal stem and the metal cap are opposed to each other, pressure is applied so as to bring them into contact with each other, current is supplied, and the metal protrusion is melted. And a method of resistance welding a metal cap.

JP-A-9-270271

  As mentioned above, when joining metal members, the method (projection welding) of providing a convex part in one metal member and carrying out resistance welding is known. This is a joining method in which an applied current is concentrated on a convex portion to locally promote heat generation and perform welding. However, in the projection welding, since the portions other than the convex portions are not welded, the conductive connection state is bad, and there is a problem that even if current is applied after joining, loss such as heat generation increases.

  For this reason, the metal members are bonded to each other at locations other than the convex portions, and it is necessary to improve the conductive connection state. Therefore, it is conceivable that solder plating is performed in advance on portions other than the convex portions and welding is performed by energizing the metal member. Simultaneously with the welding of the convex portions, the portions other than the convex portions are filled with solder melted by heat during welding, so that the metal members can be joined together to improve the conductive connection state.

  However, when the metal member connected as described above constitutes a part of the module, it is filled between the connected metal members in the reflow process for joining the module to other electronic components. When the solder is remelted, there is a problem in that the solder flows out to other electronic components or areas where adjacent wirings are arranged, thereby causing unintended conduction.

  Therefore, in order to solve the above problems, a module according to the present invention includes a first metal member having a longitudinal direction and a short direction, a second metal member, and one end of the first metal member in the longitudinal direction. A rectangular connecting portion to which a part of the second metal member is connected, and the connecting portion includes a first side and a second side along a longitudinal direction of the first metal member. A third side that connects the first side and the second side and is located at the longitudinal end of the first metal member, and a fourth side that faces the third side. A plurality of first joint portions and an inner edge portion provided with a second joint portion are provided along the inner edge of the connection portion, where the first joint portion is the first metal member and the first metal member. The second metal member is directly joined, and the second joint part is formed by joining the first metal member and the second metal member via a conductive joining material, The ratio of the total length of the widths of the first joints provided along the first side to the lengths of the first side at the inner edge of the connection surface, which is the surface in contact with the electrical bonding material And the ratio of the total length of the widths of the first joint portions provided along the second side to the length of the second side is the fourth length with respect to the length of the fourth side. It is larger than the ratio of the total length of the widths of the first joint portions provided along the sides.

  In this configuration, since the conductive bonding material remelted in the reflow process flows from the second bonding portion provided at the inner edge along the fourth side onto the first metal member, the reliability is high. You can get a module.

  The ratio of the total length of the widths of the first joints provided along the first side to the length of the first side, and the second side with respect to the length of the second side The ratio of the total length of the first joints provided along the length is the sum of the widths of the first joints provided along the third side with respect to the length of the third side. It is preferable that it is larger than the ratio of length.

  In this configuration, the conductive bonding material remelted in the reflow process is formed on the first metal member and the second metal from the second bonding portion provided along the third side and the fourth side. Since it flows on the member, a highly reliable module can be obtained.

  The total length of the total width of the first joint portions provided along the first side and the total length of the width of the first joint portions provided along the second side is the first It is preferable to be equal to the sum of the length of one side and the length of the second side.

  In this configuration, since the remelted conductive bonding material does not flow out from the first bonding portion provided along the first side and the second side, a highly reliable module can be obtained. .

  It is preferable that a plurality of first joint portions and second joint portions are provided in a region excluding the inner edge portion of the connection portion.

  In this configuration, since the conductive connection state can be further strengthened, a highly reliable module can be obtained.

  In the connection surface, it is preferable that the 1st junction part occupation rate with respect to a connection part is 31% or more and 50% or less.

  With this configuration, it is possible to obtain a highly reliable module capable of supplying a large current to the connection portion.

  According to the present invention, unintended conduction by solder can be suppressed and a highly reliable module can be provided.

It is a perspective view of module 10 which is an embodiment of a module concerning the present invention. It is sectional drawing along the thickness direction in the AA of FIG. 1 of the connection location 11 of the module 10 which is embodiment of the module which concerns on this invention. It is sectional drawing along the BB line of FIG. 2 in the direction perpendicular | vertical to the thickness direction of the connection location 11 of the module 10 which is embodiment of the module which concerns on this invention. It is a modification of the module 10 which is embodiment of the module which concerns on this invention. It is for demonstrating an example of the manufacturing method of the connection location 11 which is embodiment of the module 10 which concerns on this invention, The 1st metal member 31a and the 2nd metal member 31b, the electroconductive joining material 81, 1st It is sectional drawing along the thickness direction of the junction part 51a, the 2nd junction part 51b, and the convex part 71. FIG. 6 is a cross-sectional view according to Comparative Example 1. FIG. 6 is a cross-sectional view according to Comparative Example 2. FIG.

(Embodiment)
An embodiment of a module 10 according to the present invention is shown in FIG. FIG. 2 shows a cross-sectional view along the thickness direction of the connection portion 11 in the embodiment. FIG. 3 shows a cross-sectional view along the connection surface in a direction perpendicular to the thickness direction of the connection location 11 in the embodiment. A modification of the embodiment is shown in FIG. 5A, 5B, 5C, and 5D are cross-sectional views along the thickness direction in the manufacturing process of the connection portion 11 in the embodiment. One comparative example for the embodiment of the present invention is shown in FIG. FIG. 7 shows another comparative example for the embodiment of the present invention.

  An embodiment of a module 10 according to the present invention will be described with reference to FIGS. 1, 2, and 3.

  As shown in FIG. 1, in the module 10, for example, a plurality of second metal members 31b are bonded onto an insulating substrate 91 made of ceramic, and an electronic component 92 such as a semiconductor element is bonded to the second metal member 31b. It is a power module. Further, the first metal member 31a is connected to the second metal member 31b. A so-called lead frame is configured by connecting the first metal member 31a and the second metal member 31b.

  The first metal member 31a has a longitudinal direction and a lateral direction. Moreover, the rectangular connection part 21 which connects the 1st metal member 31a and a part of 2nd metal member 31b is provided. As shown in FIG. 1, the connection location 11 is comprised by the end of the 1st metal member 31a, a part of 2nd metal member 31b, and the connection part 21. As shown in FIG. The rectangular shape represents the shape of a region surrounded by four sides.

  FIG. 2 shows a cross-sectional view of the connection portion 11 along the thickness direction along the line AA in FIG. The connection location 11 is a rectangular shape in which the first metal member 31a, the second metal member 31b, and one end of the first metal member 31a in the longitudinal direction are connected to a part of the second metal member 31b. The connection part 21 is provided. The connection portion 21 is electrically connected to a plurality of first joint portions 51a in which the first metal member 31a and the second metal member 31b are directly coupled, and the first metal member 31a and the second metal member 31b. And a second bonding portion 51b bonded through the conductive bonding material 81 is provided. In FIG. 2, the number and shape of the first joint portion 51 a and the second joint portion 51 b at the connection location 11 are simply illustrated for the description of the connection location 11.

  FIG. 3 shows a cross-sectional view of the connection portion 11 along the direction perpendicular to the thickness direction along the line BB in FIG. The cross section along the line BB represents a connection surface, and the connection surface is a convenient surface formed by connecting the surfaces where the conductive bonding material 81 and the second metal member 31b in FIG. 2 are in contact with each other. . As shown in FIG. 2, the first metal member 31a does not exist on the connection surface, but the first metal member 31a is depicted in FIG.

  As shown in FIG. 3, the connection portion 21 includes, on the connection surface, the first side 61 a and the second side 61 b along the longitudinal direction of the first metal member 31 a, the side of the first side 61 a, and the first side 61 a. The third side 61c is connected to the second side 61b and located at the end of the first metal member 31a, and the fourth side 61d is opposed to the third side 61c. The connection portion 21 is provided with a plurality of first joint portions 51 a and second joint portions 51 b along the inner edge of the connection portion 21, and these form the inner edge portion 41. The inner edge represents the inside of the first side 61a, the second side 61b, the third side 61c, and the fourth side 61d. The inner edge portion 41 is the outermost of the first joint portions 51a provided along the inner edges of the first side 61a, the second side 61b, the third side 61c, and the fourth side 61d. Represents a region formed by the arrangement in one row. In FIG. 3, the inner edge portion 41 is formed between a region surrounded by the first side 61a, the second side 61b, the third side 61, and the fourth side 61d and a region surrounded by a broken line. Represents the area to be used.

  Further, a plurality of first joint portions 51 a and second joint portions 51 b are provided in a region excluding the inner edge portion 41 of the connection portion 21. In FIG. 3, a region excluding the inner edge portion 41 represents a region surrounded by a broken line. Moreover, the 1st junction part 51a and the 2nd junction part 51b which were provided in the area | region except the inner edge part 41 and the inner edge part 41 of the connection part 21 do not need to be provided with equal intervals, respectively.

  In the first joint portion 51a and the second joint portion 51b provided on the inner edge portion 41 of the joint portion 21, a plurality of first portions provided along the first side 61a with respect to the length of the first side 61a. The ratio of the total length of the widths of one joint portion 51a and the widths of the plurality of first joint portions 51a provided along the second side 61b with respect to the length of the second side 61b The ratio of the length is the ratio of the total length of the widths of the plurality of first joint portions 51a provided on the third side 61c to the length of the third side 61c, and the fourth side It is larger than the ratio of the total length of the plurality of first joint portions 51a provided on the fourth side 61d to the length of 61d.

  Here, the width of the first joint portion 51a refers to the size at the point where the length of the cross section of the first joint portion 51a is the longest on the connection surface. For example, in FIG. 1, since the cross-sectional shape of the first joint 51a is a circle, the width represents the diameter.

  In FIG. 3, the total length of the plurality of first joint portions 51a provided on the first side 61a is equal to the length of the first side 61a and provided on the second side 61b. The total length of the plurality of first joint portions 51a is configured to be equal to the length of the second side 61b. That is, the first joint portion 51a is formed without a gap in the first side 61a and the second side 61b. By providing this configuration, in the reflow process, the conductive bonding material 81 is provided with the first side 61a and the second side by the first joint portion 51a provided along the first side 61a and the second side 61b. It can be reliably prevented from flowing out beyond the side 61b. Accordingly, it is possible to prevent other adjacent electronic components and wirings, and other first metal members 31a and second metal members 31b from being electrically connected by the flowing conductive bonding material 81 and short-circuiting. it can.

  In the plurality of first joint portions 51a provided along the first side 61a and the second side 61b, a gap is provided between the first joint portions 51a. Also good.

  The ratio of the total length of the widths of the plurality of first joint portions 51a provided along the first side 61a to the length of the first side 61a, and the length of the second side 61b The ratio of the total length of the plurality of first joint portions 51a provided along the second side 61b is provided in the third side 61c with respect to the length of the third side 61c. The ratio of the total length of the widths of the plurality of first joint portions 51a and the width of the plurality of first joint portions 51a provided on the fourth side 61d with respect to the length of the fourth side 61d. What is necessary is just to have the relationship of becoming larger than the ratio of the total length. With this configuration, in the reflow process, the conductive bonding material 81 moves toward the third side 61c side and the fourth side 61d side where the first bonding part 51a is formed with a larger interval. Since it becomes easy, it can suppress that the conductive bonding material 81 flows out from the 2nd junction part 51b provided along the 1st edge | side 61a and the 2nd edge | side 61b. Accordingly, it is possible to prevent other adjacent electronic components and wirings, and other first metal members 31a and second metal members 31b from being electrically connected by the flowing conductive bonding material 81 and short-circuiting. it can.

  Further, as shown in FIG. 4, in the first joint portion 52a and the second joint portion 52b provided at the inner edge portion 42 of the joint portion 22, the first side 62a with respect to the length of the first side 62a. A ratio of the total length of the widths of the plurality of first joint portions 52a provided along the second side 62b and a length of the second side 62b with respect to the length of the second side 62b. The ratio of the total length of the widths of one joint portion 52a and the widths of the plurality of first joint portions 52a provided along the third side 62c with respect to the length of the third side 62c Even if the ratio of the obtained length is larger than the ratio of the total length of the widths of the plurality of first joint portions 52a provided on the fourth side 62d with respect to the length of the fourth side 62d. good. By providing this configuration, in the reflow process, the conductive bonding material easily moves to the fourth side 62d side where the first bonding portion 52a is formed with a larger interval. It is possible to prevent the conductive bonding material from flowing beyond 62a, the second side 62b, and the third side 62c. Accordingly, it is possible to prevent other adjacent electronic components and wirings, and other first metal members 32a and second metal members 32b from being electrically connected by the flowing-out conductive bonding material and short-circuiting. .

  Furthermore, the total length of the plurality of first joint portions 52a provided on the first side 62a may be equal to the length of the first side 62a. Further, the total length of the plurality of first joining portions 52a provided on the second side 62b may be equal to the length of the second side 62b. Furthermore, the total length of the plurality of first joint portions 52a provided on the third side 62c may be equal to the length of the third side 62c.

  Next, the manufacturing method of the connection location 11 of the module 10 which is embodiment of the module which concerns on this invention is demonstrated.

  As shown in FIG. 5A, a plurality of convex portions 71 are provided on a part of one surface of the second metal member 31b by chemical etching. The convex portions 71 are provided with a necessary interval as appropriate, like the first joint portion 51a in the inner edge portion 41 of FIG. The convex portion 71 preferably has a thickness of about 10% to 20% with respect to the thickness of the second metal member 31b. As shown in FIG. 5A, the convex portion 71 may have a cylindrical shape in which the area of the tip of the convex portion 71 is equal to the area of the contact point between the convex portion 71 and the second metal member 31b. A truncated cone shape in which the area of the contact point between the convex portion 71 and the second metal member 31b is larger than the area of the tip end. Further, the shape of the contact point between the tip of the convex portion 71 and the second metal member 31b may be a circle, a square, or a triangle.

  As shown in FIG. 5B, a conductive bonding material 81 is applied between the plurality of convex portions 71 provided on the second metal member 51b by chemical etching. The conductive bonding material 81 may be applied by plating, for example.

  As shown in FIG. 5C, one end in the longitudinal direction of the first metal member 31 a is arranged so as to cover the convex portion 71 of the second metal member 31 b and the conductive bonding material 81.

  As shown in FIG.5 (d), the convex part 71 and the electroconductive joining material 81 of the 2nd metal member 31b, and the end of the longitudinal direction of the 1st metal member 31a are joined with a resistance welding machine (projection welding). ) The convex portion 71 is crushed and welded to the first metal member 31a by the load and the energization in the resistance welder. In addition, the conductive bonding material 81 is melted by heat generated when the convex portion 71 is welded, and spreads on one end of the first metal member 31a. Accordingly, the conductive bonding material 81 is filled between the first metal member 31a and the second metal member 31b, and after cooling, the first metal member 31a and the second metal member 31b are fixed. The Thus, the first metal member 31a and the second metal member 31b are directly joined to each other at one end in the longitudinal direction of the first metal member 31a and a part of the metal member of the second metal member 31b. A first joining portion 51a, a second joining portion 51b in which the first metal member 31a and the second metal member 31b are joined via the conductive joining material 81, and a plurality of first joining portions 51a The connection part 21 formed by providing the second bonding part 51b is formed.

  5A, 5B, and 5C, the convex portion 71 is provided on the second metal member 31b, but may be provided on the first metal member 31a.

  The first metal member 31a and the second metal member 31b may be made of Cu, Ag, Al, Ni, Au, an alloy containing these metals, or the like. It is preferable. The conductive bonding material 81 is preferably made of Sn, Cu, Ag, Ni, Mo, or an alloy thereof.

(Example 1)
Copper lead wiring with a thickness of 0.8 mm was used for the first metal member 31a and the second metal member 31b.

  A part of one surface of the second metal member 31b was chemically etched to form a plurality of convex portions 71 having a size of 0.05 mmφ × 0.1 mmt. Convex portions 71 were formed in the same arrangement as the first joint portions 31a in the connection portion 21 of FIG. Specifically, the protrusions 71 are formed in a line without a gap along the first side 61a and the second side 61b in the connection portion 21 of FIG. 3, and the third side 61c and the fourth side 61d are formed. The inner edge portions 41 shown in FIG. 3 were formed in a row so that the interval between the adjacent convex portions 71 was 0.5 mm. Further, in the region excluding the inner edge portion 41 of the connection portion 21 in FIG. 3, the convex portion 71 provided along the first side 61a, the second side 61b, the third side 61c, and the fourth side 61d. A plurality of convex portions 71 were formed in accordance with the arrangement. Under the present circumstances, the convex part 71 was formed supposing that the connection part 21 of a 5.0 mm x 5.5 mm dimension was formed. Moreover, when the connection part 21 is formed, the ratio of the total area of the plurality of first joint parts 31a in the connection part 21 to the area of the connection part 21 (occupation ratio of the first joint part) is 37%. Thus, the convex part 71 was provided. The area of the first joint portion 31a is the area at the contact point between the convex portion 71 and the second metal member 31b.

  The surface of the second metal member 31b on which the convex portion 71 was formed was subjected to Ni plating with a thickness of 0.001 mm. Furthermore, Sn plating with a thickness of 0.02 mm was applied to the region excluding the plurality of convex portions 7 provided on the second metal member 31b in the connection portion 21 of FIG. Further, Ni plating having a thickness of 0.001 mm was applied to one surface of the first metal member.

  The surface of the first metal member 31a on which Ni plating was applied at one end in the longitudinal direction was disposed so as to cover the convex portion 71 and the conductive bonding material 81 of the second metal member 31b.

  The projection 71 and the conductive bonding material 81 of the second metal member 31b and one end in the longitudinal direction of the first metal member 31a were projection welded by a resistance welder. The 1st junction part 31a, the 2nd junction part 31b, and the connection part 21 were formed by projection welding.

(Comparative Example 1)
As Comparative Example 1, as shown in FIG. 6, the configuration of the connection portion 23 is provided along the first side 63a, the second side 63b, the third side 63c, and the fourth side 63d of the connection unit 23. A module in which the distance between the adjacent first connection portions 53a was 0.5 mm was created. In the region excluding the inner edge portion 43 of the connection portion 23, an array of the first joint portions 53a provided along the first side 63a, the second side 63b, the third side 63c, and the fourth side 63d In accordance with the above, a plurality of first joint portions 53a were formed. Other conditions such as dimensions and materials are the same as those in the first embodiment.

(Comparative Example 2)
As Comparative Example 2, as shown in FIG. 7, the first joint portion 54 a is connected along the first side 64 a, the second side 64 b, the third side 64 c, and the fourth side 64 d of the connection portion 24. Modules formed in a row without gaps were created. In the region excluding the inner edge portion 44 of the connection portion 24, including the first joint portion 54 a in the inner edge portion 44, a plurality of first joint portions 54 a are provided so that the first joint portion occupancy is 37%. Provided. Other conditions such as dimensions and materials are the same as those in the first embodiment.

(Experiment)
Each module formed as described above was subjected to a reflow test and a test in which a current of 200 A was applied.

  In Example 1, Comparative Example 1 and Comparative Example 2, A (the distance between adjacent first joints on the first side and the second side), B (adjacent on the third side and the fourth side) Table 1 below shows the results of investigating the interval between the first joints), the state after the reflow test, and the state at the time of 200A energization.

  The reflow test was performed by reflowing the module 10.

  As a result of the reflow test, the distance between the first joints 51a on the first side 61a and the second side 61b is larger than the distance between the first joints 51a on the third side 61c and the fourth side 61d. In the small Example 1, the conductive bonding material 81 remelted in the reflow process did not flow out, and the result was good.

  As a result of the reflow test, in Comparative Example 1, the distance between the first joint portions 53a on the first side 63a and the second side 63b is equal to the first joint on the third side 63c and the fourth side 63d. Since it was equal to the interval between the parts 53a, the conductive bonding material remelted in the reflow process flowed out beyond the first side 63a and the second side 63b. In the module 10 as shown in FIG. 1, when the remelted conductive bonding material flows out beyond the first side 63 a and the second side 63 b, another adjacent first metal member 33 a or second The metal member 33b was electrically connected by a conductive bonding material and short-circuited.

  As a result of the reflow test, in Comparative Example 2, electrode peeling occurred. This is because the first joint portion 54a is formed in a line without a gap along the first side 64a, the second side 64b, the third side 64c, and the fourth side 64d of the joint portion 24. This is because the conductive bonding material expands and the internal pressure increases in the reflow process.

  Moreover, in Example 1 where the reflow test result was good, the state at the time of 200 A energization was investigated. In Example 1, since the connection part 21 was densely formed by the first joint part 51a and the second joint part 51b, good results were obtained even when a large current was applied.

(Example 2)
As Example 2, the occupation ratio of the first joint portion with respect to the area of the connection portion 21 was set to 50%. Other conditions such as dimensions and materials were the same as in Example 1. Moreover, the 1st junction part 31a was formed in a line without gap along the 1st edge | side 61a and the 2nd edge | side 61b of the connection part 21. FIG.

(Example 3)
As Example 3, the occupation ratio of the first joint portion with respect to the area of the connection portion 21 was 31%. Other conditions such as dimensions and materials were the same as in Example 1. Moreover, the 1st junction part 31a was formed in a line without gap along the 1st edge | side 61a and the 2nd edge | side 61b of the connection part 21. FIG.

(Example 4)
As Example 4, the occupation ratio of the first joint portion with respect to the area of the connection portion 21 was 71%. Other conditions such as dimensions and materials were the same as in Example 1. Moreover, the 1st junction part 31a was formed in a line without gap along the 1st edge | side 61a and the 2nd edge | side 61b of the connection part 21. FIG.

(Example 5)
As Example 5, the occupation ratio of the first joint portion with respect to the area of the connection portion 21 was 21%. Other conditions such as dimensions and materials were the same as in Example 1. Moreover, the 1st junction part 31a was formed in a line without gap along the 1st edge | side 61a and the 2nd edge | side 61b of the connection part 21. FIG.

  The results of investigating the first joint occupancy ratio, the state after the reflow test, and the state at the time of 200 A energization of Example 1, Example 2, Example 3, Example 4 and Example 5 are shown in Table 2 below. Shown in

  As a result of the reflow test, in all of Example 1, Example 2, Example 3, Example 4, and Example 5, the conductive bonding material 81 did not flow out, and the result was good.

  As a result of investigating the state at the time of 200 A energization, the results of Example 1, Example 2, and Example 3 in which the first joint portion occupation ratio was 31% or more and 50% or less were good.

  In Example 4 where the first joint portion occupancy was larger than 50%, when a large current was applied, a part of the electrode was peeled off. This is because when the projection 71 is projection welded to form the first joint portion 51a, the occupancy rate of the projection 71 is high, so the effect of concentrating current on the projection 71 is reduced, and projection welding is performed. This is because it was partially incomplete.

  In Example 5 in which the first joint portion occupation ratio is smaller than 31%, the temperature of the joint portion 21 increased when a large current was applied. This is because the proportion of the conductive bonding material 81 having a high electrical resistivity is increased while the occupation ratio of the first bonding portion 51a is small, and the resistance value at the connection portion 21 is increased. As a result, there was a tendency for the temperature of the connecting portion 21 to rise when a large current was applied.

  Therefore, when energizing a large current, the occupation ratio of the first joint is preferably 31% or more and 50% or less.

(Summary)
As described above, the ratio of the total length of the widths of the first joint portions provided along the first side of the connection portion to the length of the first side, and the second side The ratio of the total length of the widths of the first joints provided along the second side to the length of the first side provided on the fourth side with respect to the length of the fourth side If the first joint portion occupancy with respect to the connection portion is greater than or equal to 31% and less than or equal to 50% than the ratio of the total length of the joint portions, the other first adjacent conductive joint material in the reflow process Even when a larger current is applied without flowing through the metal member and the second metal member, good results can be obtained, and a highly reliable module can be obtained.

  The present invention is not limited to the above embodiment, and can be implemented with various modifications.

DESCRIPTION OF SYMBOLS 10 ... Module 11, 12, 13, 14 ... Connection location 21, 22, 23, 24 ... Connection part 31a, 32a, 33a, 34a ... 1st metal member 31b, 32b, 33b, 34b ... 2nd metal member 41 , 42, 43, 44 ... inner edge portions 51a, 52a, 53a, 54a ... first joint portions 51b, 52b, 53b, 54b ... second joint portions 61a, 62a, 63a, 64a ... first sides 61b, 62b , 63b, 64b, second side 61c, 62c, 63c, 64c, third side 61d, 62d, 63d, 64d, fourth side 71, convex portion 81, conductive bonding material 91, insulating substrate 92, electron. parts

Claims (5)

A first metal member having a longitudinal direction and a transverse direction;
A second metal member;
One end of the first metal member in the longitudinal direction and a rectangular connection part to which a part of the second metal member is connected.
The first side and the second side along the longitudinal direction of the first metal member, and the end of the first metal member in the longitudinal direction by connecting the first side and the second side. A third side located in the portion, and a fourth side facing the third side,
Along the inner edge of the connecting part,
A plurality of first joint portions and an inner edge portion provided with a second joint portion;
In the inner edge portion, the first joint portion is formed by directly joining the first metal member and the second metal member, and the second joint portion is formed by the first metal member and the second metal member. Are joined via a conductive joining material,
In the inner edge portion of the connection surface, which is a surface where the second metal member and the conductive bonding material are in contact with each other,
The ratio of the total length of the widths of the first joint portions provided along the first side to the length of the first side, and the length with respect to the length of the second side The ratio of the total length of the first joints provided along the two sides is the first provided along the fourth side with respect to the length of the fourth side. A module that is larger than the ratio of the total length of the joints of one. The ratio of the total length of the widths of the first joints provided along the first side to the length of the first side, and the length of the second side, The ratio of the total length of the first joints provided along the second side is:
2. The module according to claim 1, wherein the module is larger than a ratio of a total length of widths of the first joint portions provided along the third side to a length of the third side.   The total length of the first joint portions provided along the first side and the total length of the first joint portions provided along the second side The module according to claim 1, wherein a sum is equal to a sum of a length of the first side and a length of the second side.   The module according to claim 1, wherein a plurality of the first joint portions and the second joint portions are provided in a region excluding the inner edge portion of the connection portion.   5. The module according to claim 1, wherein an occupancy ratio of the first joint portion with respect to the connection portion is 31% or more and 50% or less on the connection surface.