Semiconductor module

Abstract

The invention provides a semiconductor module which can reduce the stress applied to a conductive bonding material for bonding a substrate and a lead terminal, and can reduce the supply amount of the conductive bonding material required for bonding. This semiconductor module (1) is provided with: a semiconductor chip; a substrate (70) on which the semiconductor chip is disposed; the bonding part (65) is bonded to a lead terminal (62) on the substrate (70) through a conductive bonding material (18); and a molding resin that seals at least a part of the semiconductor chip, the substrate 70, and the shade terminal 62. The lead terminal (62) has protruding sections (12a, 12b), which protrude toward the substrate (70) side, at the joint section (65).

Description

Technical Field

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

[0002] Conventionally, there is known a semiconductor module including a semiconductor chip, a substrate on which the semiconductor chip is arranged, and lead terminals whose joint portions are joined to the substrate via a conductive joining material (solder) (see Patent Document 1 below).

[0003] [Prior art literature]

[0004] [Patent Document 1] International Publication No. 2021 / 117129

[0005] However, in this semiconductor module, due to the difference in linear expansion coefficients between the molding resin and the lead terminals, when the lead terminals expand or contract due to temperature changes, the molding resin will restrict the movement of the lead terminals. Therefore, it is possible that a large stress is applied to the conductive bonding material that joins the substrate and the lead terminals, causing cracks, thereby increasing the resistance value of the bonding portion and reducing reliability. In addition, if the thickness is increased in order to alleviate the stress applied to the conductive bonding material, it becomes a problem to ensure the supply of the conductive bonding material. When the width of the lead terminal is increased for the purpose of reducing inductance, etc., the bonding area will become larger, so the above-mentioned issue becomes more important.

[0006] Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a semiconductor module that can reduce stress applied to a conductive bonding material bonding a substrate and lead terminals, and can reduce the supply amount of the conductive bonding material required for bonding. Summary of the invention

[0007] The semiconductor module of the present invention comprises: a semiconductor chip; a substrate on which the semiconductor chip is arranged; a lead terminal whose joining portion is joined to the substrate by a conductive joining material; and a molding resin that seals at least a portion of the semiconductor chip, the substrate and the lead terminal, characterized in that the lead terminal has a protrusion at the joining portion that protrudes toward the substrate side.

[0008] Effects of the Invention

[0009] In the semiconductor module of the present invention, the presence of a portion capable of increasing the thickness of the conductive bonding material can reduce stress applied to the conductive bonding material bonding the substrate and the lead terminal, and the presence of a protruding portion can reduce the amount of conductive bonding material required for bonding.

[0010] Simple illustration

[0011] Figure 1It is a plan view of the internal configuration of the semiconductor module 1 according to the first embodiment.

[0012] Figure 2 It is a perspective view showing the structure of the lead terminal 62 .

[0013] Figure 3 It is a diagram for explaining the shape of the bonding portion 65 of the lead terminal 62 .

[0014] Figure 4 Results of thermal stress simulation using the semiconductor module 1 according to the first embodiment.

[0015] Figure 5 It is a diagram for explaining the shape of the bonding portion 165 of the lead terminal 162 .

[0016] Figure 6 It is a diagram showing the results of thermal stress simulation using the semiconductor module 3 according to the second embodiment.

[0017] Figure 7 This is a diagram for explaining the shape of a bonding portion 365 of a lead terminal 362 constituting a conventional semiconductor module 300 .

[0018] Figure 8 1 is a diagram showing the results of a thermal stress simulation using a conventional semiconductor module 300 . DETAILED DESCRIPTION

[0019] The semiconductor modules of various embodiments are described below. In the various embodiments described below, the same symbols are used across the embodiments for components having substantially the same functions, and the description thereof is omitted. The various embodiments described below do not limit the inventions of the claims. In addition, not all of the elements and their combinations described in the various embodiments are necessary for the solutions of the present invention.

[0020] (First Embodiment)

[0021] Below, refer to Figure 1 The internal structure of the semiconductor module 1 according to the first embodiment will be described. Figure 1 As shown, the semiconductor module 1 of 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, 53. The end portions (joint portions) of the inner lead portions of the lead terminals 51, 52, 53 are located inside the mold resin M, and the outer lead portions of the lead terminals 51, 52, 53 are located outside the mold resin M.

[0022] The semiconductor module 1 includes four semiconductor chips (first to fourth semiconductor chips Q1 to Q4) as a plurality of semiconductor chips and lead terminals 61 and 62 to form a bridge circuit.

[0023] In addition, in addition to the above-mentioned components, the semiconductor module 1 also includes: first to fifth wiring patterns 10 to 50, a substrate 70, first to fourth connecting members 81 to 84, first to fourth control connecting members (not shown in the figure), first to fourth detection connecting members (not shown in the figure), first to fourth control wiring patterns 111 to 114, first to fourth detection wiring patterns 121 to 124, first to fourth control terminals T11 to T14, and first to fourth detection terminals T21 to T24. In addition, the first to fifth wiring patterns 10 to 50 constitute a part of the substrate 70. The semiconductor module 1 may also have components other than the above-mentioned. In the semiconductor module 1, a bridge circuit is configured in which the first semiconductor chip Q1 and the third semiconductor chip Q3 are set to the high side and the second semiconductor chip Q2 and the fourth semiconductor chip Q4 are set to the low side.

[0024] 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 symmetrically arranged 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 terminal 52 and the lead terminal 53, and the lead terminal 61 and the lead terminal 62 are also symmetrically arranged with respect to the center line C. In addition, the fifth wiring pattern 50 and the lead terminal 51 are formed symmetrically with respect to the center line C.

[0025] The lead terminal 51 is composed of lead terminals 56 and 57 functioning as input power terminals. The lead terminals 52 and 53 function as input power terminals. The lead terminals 61 and 62 function as output power terminals.

[0026]

Lead terminal structure

[0027] Hereinafter, the structures of the lead terminals 52, 53, 56, 57, 61, 62 will be described, but since the structures of the bonding portions 54, 55, 58, 59, 64, 65 are substantially the same, the lead terminal 62 will be described as an example, and the description of the other lead terminals 52, 53, 56, 57, 61 will be omitted. In addition, although the bonding portions of the lead terminals 52, 53, 56, 57, 61, 62 are bonded to the wiring pattern of the substrate 70, in the following description, the wiring pattern is also described as a part of the substrate 70.

[0028] like Figure 3 As shown, the lead terminal 62 has a joint portion 65 at the front end that is joined to the fourth wiring pattern 40 through a conductive bonding material 18. In addition, in the present embodiment, the conductive bonding material 18 is solder (solder in a broad sense, including lead-free solder, etc.). The joint portion 65 has protrusions 12a and 12b that protrude from the outer peripheral end surface 23 of the joint portion 65 toward the surface (upper surface) of the substrate 70 on which the fourth wiring pattern 40 is formed. The protrusions 12a and 12b are configured to be in contact with the edges of the joint portion 65. Figure 2 In the example of FIG. 1 , two protrusions 12a and 12b are formed at a predetermined interval, but it is also possible to Figure 5 Only one protrusion 22 is formed as shown, but three or more protrusions may be formed at predetermined intervals (not shown). The protrusions 12a and 12b are formed by stamping from the upper surface of the joint 65, but the forming method is not limited thereto. The recesses 14a and 14b are formed (byproducts) when the protrusions 12a and 12b are formed by stamping. The height H of the protrusions 12a and 12b is preferably not less than 0.1 mm and not more than half of the plate thickness D of the joint 65.

[0029] The conductive bonding material 18 in a paste form is applied (e.g., printed) on the substrate 70, and when heat is applied after the lead terminal 62 is mounted, 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 infiltrates and diffuses in the space between the adjacent protrusions 12a and 12b.

[0030]

Thermal stress simulation

[0031] Next, the thickness of the conductive bonding material in the portion of the lower end surface of the bonding portion 65 where the protrusions 12a and 12b are not present is set to 0.15 mm (see Figure 3 ), the thermal stress applied to the conductive bonding material 18 bonding the bonding lead terminal 56, the lead terminal 57, the lead terminal 52, the lead terminal 53, the lead terminal 61, the lead terminal 62 and the substrate 70 was measured. On the other hand, in the comparative example (conventional structure), the thermal stress applied to the conductive bonding material 18 bonding the bonding lead terminal 56, the lead terminal 57, the lead terminal 52, the lead terminal 53, the lead terminal 61, the lead terminal 62 and the substrate 70 were measured. Figure 8 The stress at the lead terminals 352, 353, 356, 357, 361, 362 of the semiconductor module 300 shown in the figure and at the conductive bonding material 348 of the bonding substrate 370. Figure 7 The temperature change condition for generating thermal stress was set to -55°C to 175°C (temperature difference 230°C).

[0032] The simulation results of the thermal stress simulation of the first embodiment are as follows: Figure 4As shown, the lead terminal 56 is 376 MPa, the lead terminal 57 is 389 MPa, the lead terminal 52 is 348 MPa, the lead terminal 53 is 361 MPa, the lead terminal 61 is 371 MPa, and the lead terminal 62 is 390 MPa. The simulation results of the thermal stress simulation in the comparative example (comparative example) are as follows Figure 8 As shown, the lead terminal 356 is 490MPa, the lead terminal 357 is 485MPa, the lead terminal 352 is 390MPa, the lead terminal 353 is 418MPa, the lead terminal 361 is 475MPa, and the lead terminal 362 is 502Mpa. Therefore, according to the structure of the present embodiment, it can be seen that the thermal stress applied to the conductive bonding material 18 that respectively bonds the lead terminals 52, 53, 56, 57, 61, and 62 to the substrate 370 is greater than the thermal stress applied to the conductive bonding material 348 that bonds the lead terminals 352, 353, 356, 357, 361, and 362 at the same position to the substrate 70 based on the conventional structure (structure without protrusions 12a and 12b) (refer to Figure 8 ) is lower than that of

[0033] According to the above structure, due to the difference in linear expansion coefficients between the molding resin M and the lead terminal 62, even when the lead terminal 62 expands or contracts due to temperature changes, the thickness of the conductive bonding material 18 (solder thickness) is further increased by the amount of the height H of the protrusions 12a and 12b, thereby suppressing the generation of cracks. Therefore, it is possible to suppress the stress applied to the conductive bonding material 18 that joins the substrate 70 and the lead terminal 62. In addition, compared with the case where the thickness of the conductive bonding material 18 is simply increased in order to alleviate the stress applied to the conductive bonding material 18, it is also easier to reduce the supply amount of the conductive bonding material 18 due to the presence of the protrusions 12a and 12b. Therefore, according to the above structure, it is possible to reduce the stress applied to the conductive bonding material 18 that joins the substrate 70 and the lead terminal 62, and it is possible to achieve a reduction in the supply amount of the conductive bonding material 18 required for joining.

[0034] In addition, even when the width of the lead terminal is expanded for the purpose of low inductance, a large amount of conductive bonding material (solder) is required, but the amount of conductive bonding material that can be stably applied to the substrate is limited, so it is preferably reduced as much as possible. According to the above structure, by appropriately adjusting the height and size of the protrusion, the supply amount of the conductive bonding material is easily adjusted, and the effect of increasing the degree of adjustment freedom can be obtained. In addition, since the protrusion can be provided to increase the bonding area, the bonding strength can be easily increased.

[0035] (Second Embodiment)

[0036] The semiconductor module 3 of the second embodiment is different from the semiconductor module 1 of the first embodiment in that only one protrusion 22 is formed. Hereinafter, only the differences will be described, and the description of the same parts will be omitted. In addition, in the following, as in the first embodiment described above, the lead terminal 162 will be used as an example for description, and the structures of the other lead terminals 152, 153, 156, 157, and 161 will be omitted.

[0037] like Figure 5 As shown, the lead terminal 162 has a joint portion 165 at the front end that is joined to the fourth wiring pattern 40 through a conductive bonding material 28. The joint portion 165 has a protrusion 22 that protrudes from the outer peripheral end surface (not shown in the figure) of the joint portion 165 toward the surface (upper surface) of the substrate 70 on which the fourth wiring pattern 40 is formed. The protrusion 22 is formed by stamping from the upper surface of the joint portion 165, but the formation method is not limited to this. The recess 24 is formed (by-product) when the protrusion is formed by stamping. The height H of the protrusion 22 is preferably greater than 0.1 mm and less than half of the plate thickness D of the joint portion 165.

[0038] The conductive bonding material 28 in a paste state is applied (e.g., printed) in advance on the substrate 70, and when heat is applied after the lead terminal 162 is mounted, the conductive bonding material 28 melts, and the bonding portion 165 is bonded to the substrate 70. At this time, the conductive bonding material 28 also infiltrates and diffuses into the space below the outer peripheral end surface 63 of the bonding portion 165 where the protrusion 22 does not exist.

[0039]

Thermal stress simulation

[0040] In the following, the thickness of the conductive bonding material 28 (solder thickness) between the lower end surface of the protrusion 22 and the substrate 70 is assumed to be 0.05 mm (see Figure 5 ), the thickness of the conductive bonding material 28 in the portion of the lower end surface of the bonding portion 165 where the protrusion 22 is not present is 0.15 mm (refer to Figure 5 ), the thermal stress applied to the lead terminal 156, the lead terminal 157, the lead terminal 152, the lead terminal 153, the lead terminal 161, the lead terminal 162, and the conductive bonding material 28 applied to the bonding substrate 70 was measured. On the other hand, in the comparative example (conventional structure), the thermal stress applied to the structure Figure 8 The thermal stress at the lead terminals 352, 353, 356, 357, 361, 362 of the semiconductor module 300 shown in the figure and at the conductive bonding material 348 of the bonding substrate 370. Figure 7 The temperature change conditions for generating thermal stress are the same as those in the first embodiment.

[0041] The results of the thermal stress simulation of the second embodiment are as follows: Figure 6 As shown in FIG. 1 , the lead terminal 156 is 361 MPa, the lead terminal 157 is 367 MPa, the lead terminal 152 is 370 MPa, the lead terminal 153 is 365 MPa, the lead terminal 161 is 384 MPa, and the lead terminal 162 is 364 MPa. Therefore, according to the structure of the present embodiment, the thermal stress applied to the lead terminals 152, 153, 156, 157, 161, 162 and the conductive bonding material 28 of the bonding substrate 70 is greater than the thermal stress applied to the lead terminals 352, 353, 356, 357, 361, 362 and the conductive bonding material 348 of the bonding substrate 370 at the same positions according to the conventional structure (comparative example) (refer to FIG. 1 ). Figure 8 ) compared to .

[0042] (Effect Summary)

[0043] The semiconductor module of the above embodiment is a semiconductor module comprising a semiconductor chip, a substrate on which the semiconductor chip is arranged, a lead terminal whose joint portion is joined to the substrate via a conductive bonding material, and a molding resin that seals at least a portion of the semiconductor chip, the substrate, and the lead terminal, wherein the lead terminal has a protruding portion protruding toward the substrate at the joint portion. Therefore, according to the above structure, the presence of a portion that can increase the thickness of the conductive bonding material can reduce the stress applied to the conductive bonding material that joins the substrate and the lead terminal, and the presence of the protruding portion can reduce the amount of conductive bonding material required for joining.

[0044] In the semiconductor module of the above-mentioned embodiment, the lead terminal can be provided with a plurality of protrusions as the protrusion. 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 can be obtained. In addition, by providing a plurality of protrusions, the bonding area between the bonding portion and the conductive bonding material can be increased, so that the bonding strength can be increased.

[0045] In the semiconductor module of the above-mentioned embodiment, it is preferred that the protrusion height of the protrusion protruding toward the substrate side is greater than 0.1 mm and less than half of the plate thickness of the joint. The reason for determining the height of the protrusion as described above is that if the height of the protrusion is high, more conductive bonding material is required, and if the height of the protrusion is too high, it is difficult for the protrusion and the gap between the protrusions to be wetted and diffused as a whole. This is because, if the height of the protrusion is too low, it is sometimes difficult to ensure the thickness of the conductive bonding material and it is difficult to relieve stress. Therefore, by controlling the height of the protrusion to be greater than 0.1 mm and less than half of the plate thickness of the joint, the effect of easily wetting and spreading the conductive bonding material can be obtained.

[0046] In the semiconductor module of the above embodiment, the protrusion is preferably arranged to be in contact with the edge of the joint. When the protrusion is not in contact with the edge, the size of the protrusion becomes smaller and the required amount of conductive bonding material increases. However, by arranging the protrusion to be in contact with the edge of the joint, the size of the protrusion can be increased, so the effect of reducing the conductive bonding material can be expected.

[0047] In the semiconductor module of 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, the protrusion can be arranged in contact with the edge, a larger protrusion can be formed, and the supply amount of the conductive bonding material can be reduced.

[0048] The present invention is not limited to the above-described embodiment, and various modifications can be implemented without departing from the gist of the present invention. For example, in addition to bonding to a wiring pattern on a substrate, bonding to a semiconductor chip is also conceivable.

[0049] Explanation of symbols

[0050] 1, 3, 300…Semiconductor module

[0051] 12a, 12b, 22 ... protrusion

[0052] 14a, 14b, 24... concave portion

[0053] 18, 28…Conductive bonding material (solder)

[0054] 51, 52, 53, 56, 57, 61, 62, 152, 153, 156, 157, 161, 162…lead terminals

[0055] 54, 55, 58, 59, 64, 65, 154, 155, 158, 159, 164, 165...Joint

[0056] 70…Substrate

[0057] Q1, Q2, Q3, Q4…semiconductor chips

[0058] M…molding resin.

Claims

1. A semiconductor module, comprising: Semiconductor chips; a substrate provided with the semiconductor chip; The bonding portion is bonded to the lead terminal of the substrate through a conductive bonding material; as well as The mold resin that seals at least a portion of the semiconductor chip, the substrate, and the lead terminals is characterized by: The lead terminal has a protrusion at the joining portion that protrudes toward the substrate.

2. The semiconductor module according to claim 1, characterized in that: The lead terminal has a plurality of protrusions as the protrusions.

3. The semiconductor module according to claim 1, wherein: A protrusion height of the protrusion portion toward the substrate is not less than 0.1 mm and not greater than half the thickness of the bonding portion.

4. The semiconductor module according to claim 1, wherein: The protrusion is configured not to come into contact with an edge of the engagement portion.

5. The semiconductor module according to claim 1, wherein: The joining portion is located at an end portion of the lead terminal.

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