Semiconductor module

Abstract

To provide a semiconductor module capable of reducing the stress applied to a conductive bonding material that bonds a substrate to a lead terminal and also capable of reducing the supply of conductive bonding material required for bonding.SOLUTION: A semiconductor module 1 comprises a semiconductor chip, a substrate 70 on which the semiconductor chip is arranged, a lead terminal 62 whose junction 65 is bonded to the substrate 70 by a conductive bonding material 18, and a molding resin that encapsulates at least a portion of the semiconductor chip, substrate 70, and lead terminal 62. The lead terminal 62 has protruding portions 12a and 12b protruding from the side of substrate 70 at the junction 65.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a semiconductor module. [Background technology]

[0002] Conventionally, a semiconductor module has been known that includes a semiconductor chip inside a molded resin, a substrate on which the semiconductor chip is disposed, and lead terminals whose joints are joined to the substrate by a conductive bonding material (solder) (see Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 117129 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in such a semiconductor module, due to the difference in the linear expansion coefficient between the mold resin and the lead terminals, the movement of the lead terminals is restricted by the mold resin when the lead terminals expand or contract due to temperature changes. This causes a large stress to be applied to the conductive bonding material that bonds the substrate and the lead terminals, which may cause cracks to occur, increasing the resistance of the bonding portion and reducing reliability. Furthermore, if the thickness is increased to relieve the stress applied to the conductive bonding material, ensuring the supply of the conductive bonding material becomes an issue. If the width of the lead terminals is increased for the purpose of reducing inductance, etc., the bonding area becomes larger, making the above issue even more important.

[0005] Therefore, the present invention has been made in consideration of the above problems, and aims to provide a semiconductor module that is capable of reducing the stress applied to the conductive bonding material that bonds the substrate and the lead terminals, and that is capable of reducing the amount of conductive bonding material required for bonding. [Means for solving the problem]

[0006] The semiconductor module of the present invention is a semiconductor module comprising a semiconductor chip, a substrate on which the semiconductor chip is arranged, a lead terminal having a joint portion joined to the substrate by a conductive bonding material, and a molded resin that seals at least the semiconductor chip, the substrate and a portion of the lead terminal, wherein the lead terminal has a protrusion that protrudes toward the substrate at the joint portion. Effect of the Invention

[0007] In the semiconductor module of the present invention, the presence of a portion where the thickness of the conductive bonding material can be increased makes it possible to reduce the stress applied to the conductive bonding material that bonds the substrate and the lead terminals, and the presence of a protrusion makes it possible to reduce the amount of conductive bonding material required for bonding. [Brief description of the drawings]

[0008] [Figure 1] 1 is a plan view showing an internal configuration of a semiconductor module 1 according to a first embodiment. [Diagram 2] 2 is a perspective view showing the structure of a lead terminal 62. FIG. [Diagram 3] 2 is a diagram for explaining the shape of a joint 65 of a lead terminal 62. FIG. [Figure 4] 5A to 5C are diagrams showing the results of a thermal stress simulation using the semiconductor module 1 according to the first embodiment. [Diagram 5] 13 is a diagram for explaining the shape of a joint portion 165 of a lead terminal 162. FIG. [Figure 6] 13 is a diagram showing the results of a thermal stress simulation using the semiconductor module 3 according to the second embodiment. FIG. [Figure 7] 13 is a diagram for explaining the shape of a joint 365 of a lead terminal 362 constituting a conventional semiconductor module 300. FIG. [Figure 8] 13 is a diagram showing the results of a thermal stress simulation using a conventional semiconductor module 300. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The semiconductor module according to each embodiment will be described below. In each embodiment described below, components having substantially the same functions are designated by the same reference numerals across the embodiments, and repeated description will be omitted. Each embodiment described below does not limit the invention according to the claims. Furthermore, not all of the elements and combinations thereof described in each embodiment are necessarily essential to the solution of the present invention.

[0010] (First embodiment) The internal configuration of a semiconductor module 1 according to the first embodiment will be described below with reference to Fig. 1. As shown in Fig. 1, the semiconductor module 1 according to the first embodiment includes a plurality of semiconductor chips arranged inside a mold resin (only the outer edge is indicated by the symbol M), and lead terminals 51, 52, and 53. The end portions (joint portions) of the inner lead portions of the lead terminals 51, 52, and 53 are located inside the mold resin M, and the outer lead portions are located outside the mold resin M.

[0011] The semiconductor module 1 includes four semiconductor chips (first to fourth semiconductor chips Q1 to Q4) as the multiple semiconductor chips, and further includes lead terminals 61 and 62 to configure a bridge circuit. Ends (joints) of the inner lead portions of the lead terminals 61 and 62 are located inside the molding resin M.

[0012] In addition to the above-mentioned components, the semiconductor module 1 includes the first to fifth wiring patterns 10 to 50, the substrate 70, the first to fourth connection members 81 to 84, the first to fourth control connection members (reference numbers are not shown), the first to fourth detection connection members (reference numbers are not shown), the first to fourth control wiring patterns 111 to 114, the first to fourth detection wiring patterns 121 to 124, the first to fourth control terminals T11 to T14, and the first to fourth detection terminals T21 to T24. The first to fifth wiring patterns 10 to 50 form a part of the substrate 70. The semiconductor module 1 may further include components other than those described above. In the semiconductor module 1, a bridge circuit is formed in which the first semiconductor chip Q1 and the third semiconductor chip Q3 are on the high side and the second semiconductor chip Q2 and the fourth semiconductor chip Q4 are on the low side.

[0013] In the semiconductor module 1, the first semiconductor chip Q1 and the third semiconductor chip Q3, and the second semiconductor chip Q2 and the fourth semiconductor chip Q4 are each arranged symmetrically with respect to the center line C. In addition, the first wiring pattern 10 and the third wiring pattern 30, the second wiring pattern 20 and the fourth wiring pattern 40, the lead terminals 52 and 53, and the lead terminals 61 and 62 are also each arranged symmetrically with respect to the center line C. In addition, the fifth wiring pattern 50 and the lead terminals 51 are each formed symmetrically with respect to the center line C.

[0014] The lead terminal 51 is made up of lead terminals 56 and 57 which function as input power supply terminals. The lead terminals 52 and 53 function as input power supply terminals. The lead terminals 61 and 62 function as output power supply terminals.

[0015] [Lead terminal structure] The structures of lead terminals 52, 53, 56, 57, 61, and 62 will be described below, but because the structures of joints 54, 55, 58, 59, 64, and 65 are generally the same, the structure will be described using lead terminal 62 as an example, and the structures of the other lead terminals 52, 53, 56, 57, and 61 will be omitted. In addition, the joints of each of lead terminals 52, 53, 56, 57, 61, and 62 are joined to the wiring pattern of substrate 70, but in the following description, the wiring pattern will also be considered as part of substrate 70.

[0016] As shown in FIG. 3, the lead terminal 62 has a joint 65 at its tip which is joined to the fourth wiring pattern 40 via a conductive joint material 18. In this embodiment, the conductive joint material 18 is solder (solder in a broad sense, including lead-free solder). The joint 65 has protrusions 12a and 12b protruding from the outer peripheral end surface 23 of the joint 65 toward the surface (upper surface) on which the fourth wiring pattern 40 of the substrate 70 is formed. The protrusions 12a and 12b are arranged so as to contact the edge of the joint 65. In the example of FIG. 2, two protrusions 12a and 12b are formed at a predetermined interval, but only one protrusion 22 may be formed as shown in FIG. 5, or three or more protrusions may be formed at a predetermined interval (not shown). The protrusions 12a and 12b are press-formed by pressing from the upper surface of the joint 65, but the forming method is not limited thereto. The recesses 14a and 14b are by-products that are produced when the protrusions 12a and 12b are formed by pressing. It is preferable that the height H of the protrusions 12a and 12b is 0.1 mm or more and half the plate thickness D of the joint 65 or less.

[0017] When the paste-like conductive bonding material 18 is applied (for example, by printing) onto the substrate 70 and the lead terminals 62 are mounted thereon and then heated, the conductive bonding material 18 melts and the bonding portion 65 is bonded to the substrate 70. At this time, the conductive bonding material 18 also spreads into the space between the adjacent protruding portions 12a and 12b.

[0018] [Thermal stress simulation] In the following, the thickness of the conductive bonding material at the portion where the protrusions 12a and 12b are not present on the lower end surface of the joint 65 is set to 0.15 mm (see FIG. 3), and the thermal stress applied to the conductive bonding material 18 bonding each of the lead terminals 56, 57, 52, 53, 61, and 62 to the substrate 70 was measured. On the other hand, in the comparative example (the configuration of the conventional technology), the thermal stress applied to the conductive bonding material 348 bonding each of the lead terminals 352, 353, 356, 357, 361, and 362 constituting the semiconductor module 300 shown in FIG. 8 to the substrate 370 was measured. No protrusions are formed at the joints of these lead terminals (for example, the joint 365 in FIG. 7). The temperature change condition for generating the thermal stress was set to -55°C to 175°C (temperature difference 230°C).

[0019] 4, the simulation results of the thermal stress simulation in the first embodiment were 376 MPa for lead terminal 56, 389 MPa for lead terminal 57, 348 MPa for lead terminal 52, 361 MPa for lead terminal 53, 371 MPa for lead terminal 61, and 390 MPa for lead terminal 62. The simulation results of the thermal stress simulation in the comparative example (comparative example) were 490 MPa for lead terminal 356, 485 MPa for lead terminal 357, 390 MPa for lead terminal 352, 418 MPa for lead terminal 353, 475 MPa for lead terminal 361, and 502 MPa for lead terminal 362, as shown in FIG. Therefore, according to the configuration of this embodiment, it can be seen that the thermal stress applied to the conductive bonding material 18 bonding each of the lead terminals 52, 53, 56, 57, 61, 62 to the substrate 370 is reduced compared to the thermal stress (see Figure 8) applied to the conductive bonding material 348 bonding the lead terminals 352, 353, 356, 357, 361, 362 to the substrate 70 at the same locations in the conventional configuration (configuration not having protrusions 12a, 12b).

[0020] According to the above-mentioned configuration, even when the lead terminal 62 expands or contracts due to a change in temperature due to the difference in the linear expansion coefficient between the mold resin M and the lead terminal 62, the thickness (solder thickness) of the conductive bonding material 18 is further increased by the height H of the protrusions 12a and 12b, so that the occurrence of cracks is suppressed. Therefore, it is possible to suppress the stress applied to the conductive bonding material 18 that bonds the substrate 70 and the lead terminal 62. In addition, compared to the case where only the thickness of the conductive bonding material 18 is increased to relieve the stress applied to the conductive bonding material 18, the presence of the protrusions 12a and 12b makes it easier to reduce the supply amount of the conductive bonding material 18. Therefore, according to the above-mentioned configuration, it is possible to reduce the stress applied to the conductive bonding material 18 that bonds the substrate 70 and the lead terminal 62, and it is also possible to reduce the supply amount of the conductive bonding material 18 required for bonding.

[0021] In addition, even when the width of the lead terminal is widened for the purpose of reducing inductance, etc., a large amount of conductive bonding material (solder) is required, but since there is a limit to the amount of conductive bonding material that can be stably applied to the substrate, it is preferable to reduce it as much as possible. According to the above configuration, by appropriately adjusting the height and width of the protrusion, it is easy to adjust the supply amount of conductive bonding material, and an effect of increasing the degree of freedom of adjustment is obtained. Furthermore, since the bonding area can be increased by providing the protrusion, the bonding strength can be easily increased.

[0022] Second Embodiment The semiconductor module 3 according to the second embodiment basically differs from the semiconductor module 1 according to the first embodiment in that only one protrusion 22 is formed. In the following, only the differences will be described, and a description of the similar parts will be omitted. Note that, in the following, as in the first embodiment, the lead terminal 162 will be described as an example, and the structures of the other lead terminals 152, 153, 156, 157, and 161 will be omitted.

[0023] As shown in FIG. 5, the lead terminal 162 has a joint 165 at its tip which is joined to the fourth wiring pattern 40 via a conductive bonding material 28. The joint 165 has a protrusion 22 which protrudes from the outer peripheral end face (reference numeral not shown) of the joint 165 toward the surface (upper surface) of the substrate 70 on which the fourth wiring pattern 40 is formed. The protrusion 22 is press-formed by pressing from the upper surface of the joint 165, but the method of formation is not limited to this. The recess 24 is a by-product which is formed when the protrusion is formed by pressing. The height H of the protrusion 22 is preferably 0.1 mm or more and half or less of the plate thickness D of the joint 165.

[0024] When paste-like conductive bonding material 28 is applied (for example, printed) in advance onto substrate 70 and heat is applied after lead terminal 162 is mounted, conductive bonding material 28 melts and bonding portion 165 is bonded to substrate 70. At this time, conductive bonding material 28 spreads even in the space below outer peripheral end face 63 of bonding portion 165 where protrusion 22 is not present.

[0025] [Thermal stress simulation] In the following, the thickness (solder thickness) of the conductive bonding material 28 present between the lower end surface of the protrusion 22 and the substrate 70 was set to 0.05 mm (see FIG. 5), and the thickness of the conductive bonding material 28 at the lower end surface of the joint 165 where the protrusion 22 does not exist was set to 0.15 mm (see FIG. 5), and the thermal stress applied to the conductive bonding material 28 bonding each of the lead terminals 156, 157, 152, 153, 161, and 162 to the substrate 70 was measured. On the other hand, in a comparative example (configuration of the prior art), the thermal stress applied to the conductive bonding material 348 bonding each of the lead terminals 352, 353, 356, 357, 361, and 362 constituting the semiconductor module 300 shown in FIG. 8 to the substrate 370 was measured. No protrusion was formed at the joints of these lead terminals (for example, joint 365 in FIG. 7). The temperature change conditions for generating thermal stress were the same as those in the first embodiment.

[0026] 6, the measurement results of the thermal stress simulation in the second embodiment were 361 MPa for lead terminal 156, 367 MPa for lead terminal 157, 370 MPa for lead terminal 152, 365 MPa for lead terminal 153, 384 MPa for lead terminal 161, and 364 MPa for lead terminal 162. Therefore, according to the configuration of this embodiment, it is found that the thermal stress applied to the conductive bonding material 28 bonding each of the lead terminals 152, 153, 156, 157, 161, and 162 to the substrate 70 is reduced compared to the thermal stress (see FIG. 8) applied to the conductive bonding material 348 bonding the lead terminals 352, 353, 356, 357, 361, and 362 to the substrate 370 at the same positions in the conventional configuration (comparative example).

[0027] (Summary of effects) The semiconductor module according to the above embodiment is a semiconductor module including a semiconductor chip, a substrate on which the semiconductor chip is disposed, lead terminals having joints joined to the substrate by a conductive bonding material, and a molded resin that seals at least a portion of the semiconductor chip, the substrate, and the lead terminals, and the lead terminals have protrusions that protrude toward the substrate at the joints. Therefore, according to the above configuration, the presence of a portion that can increase the thickness of the conductive bonding material makes it possible to reduce the stress applied to the conductive bonding material that bonds the substrate and the lead terminals, and the presence of the protrusions makes it possible to reduce the amount of conductive bonding material required for bonding.

[0028] In the semiconductor module according to the above embodiment, the lead terminal may be provided with a plurality of protrusions as the protrusions. Therefore, by appropriately adjusting the height and width of the plurality of protrusions, it becomes easier to adjust the supply amount of the conductive bonding material, and the effect of increasing the degree of freedom of adjustment is obtained. Furthermore, by providing a plurality of protrusions, the bonding area between the bonding portion and the conductive bonding material can be increased, and therefore the bonding strength can be increased.

[0029] In the semiconductor module according to the above embodiment, the protrusion height to the substrate side is preferably 0.1 mm or more and less than half the plate thickness of the joint. The reason for determining the height of the protrusion as described above is that if the protrusion height is high, more conductive bonding material is required, and if the protrusion height is too high, the entire gap between the protrusions becomes difficult to wet and spread. If the protrusion height is too low, it becomes difficult to ensure the thickness of the conductive bonding material, and it may become difficult to relieve stress. Therefore, by controlling the height of the protrusion to 0.1 mm or more and less than half the plate thickness of the joint, the effect of making the conductive bonding material wet and spread easily can be obtained.

[0030] In the semiconductor module according to the above embodiment, it is preferable that the protrusion is disposed so as to contact the edge of the joint. If the protrusion is not disposed so as to contact the edge, the size of the protrusion is reduced and the amount of conductive bonding material required increases, but by disposing the protrusion so as to contact the edge of the joint, the size of the protrusion can be increased, so that the effect of reducing the amount of conductive bonding material can be expected.

[0031] In the semiconductor module according to the above embodiment, the bonding portion is preferably located at the end of the lead terminal. By forming the bonding portion at the end of the lead terminal, it is possible to arrange the protrusion so as to contact the edge, so that a larger protrusion can be formed and the amount of conductive bonding material required can be reduced.

[0032] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, the bonding portion may be bonded to a semiconductor chip other than to a wiring pattern on a substrate. [Explanation of symbols]

[0033] 1,330...Semiconductor modules 12a, 12b, 22...protrusion 14a, 14b, 24...Concave portions 18, 28...Conductive bonding material (solder) 51, 52, 53, 56, 57, 61, 62, 152, 153, 156, 157, 161, 162...Lead terminals 54,55,58,59,64,65,154,155,158,159,164,165...Joint part 70...Substrate Q1, Q2, Q3, Q4...Semiconductor chip M: Molding resin

Claims

1. A semiconductor module comprising: a semiconductor chip; a substrate on which the semiconductor chip is disposed; lead terminals having joints joined to the substrate by a conductive bonding material; and a molding resin that seals at least the semiconductor chip, the substrate, and a portion of the lead terminals, The semiconductor module, wherein the lead terminal has a protruding portion at the joint portion that protrudes toward the substrate.

2. 2. The semiconductor module according to claim 1, wherein the lead terminal has a plurality of protruding portions as the protruding portion.

3. 2. The semiconductor module according to claim 1, wherein the height of the protrusion toward the substrate is equal to or greater than 0.1 mm and is equal to or less than half the plate thickness of the joint.

4. 2. The semiconductor module according to claim 1, wherein the protruding portion is disposed so as to contact an edge of the joint portion.

5. 2. The semiconductor module according to claim 1, wherein the joint portion is provided at an end portion of the lead terminal.

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