Semiconductor module

Abstract

A semiconductor module is provided that is capable of reducing the stress exerted on a conductive interconnect material connecting a substrate and a conductor terminal, and of reducing the amount of conductive interconnect material required for such a connection. [Means to solve the problem] A semiconductor module 1 comprises: a semiconductor chip, a substrate 70 on which the semiconductor chip is arranged, a conductor connector 62 having a connecting section 65 which is connected to the substrate 70 by a conductive connecting material 18, and a casting resin which seals at least the semiconductor chip, the substrate 70 and a section of the conductor connector 62. The conductor connector 62 has protruding sections 12a 12b which project into the connecting section 65 towards one side of the substrate 70.

Description

Technical area

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

[0002] Conventionally, a semiconductor module is known in which a semiconductor chip, a substrate on which the semiconductor is arranged, and a lead terminal having a connecting portion connected to the substrate by a conductive connecting material (solder) are arranged in a mold resin (see patent literature described below). [Prior art literature][Patent literature]

[0003] [Patent Literature 1] WO2021 / 117129A1 Brief description of the inventionTechnical problem

[0004] However, in such a semiconductor module, due to a difference in linear expansion coefficient between the mold resin and the lead terminal, the movement of the lead terminal is restricted by the mold resin when the lead terminal expands or contracts due to a temperature change. Accordingly, there is a concern that a large stress is applied to the conductive interconnection material connecting the substrate and the lead terminal, and therefore a crack occurs, thereby increasing a resistance value of a connection portion and leading to a reduction in the reliability of the semiconductor module. On the other hand, if a thickness of the conductive interconnection material is increased to reduce a stress applied to the conductive interconnection material, ensuring a supply amount of the conductive interconnection material becomes a problem that needs to be solved.In a case where a width of the lead terminal is increased to implement a reduction of inductance and the like, a connection area is increased, and therefore the above-mentioned problem becomes more serious.

[0005] The present invention has been made in view of such circumstances, and an object of the present invention is to provide a semiconductor module capable of reducing a stress applied to a conductive interconnection material that interconnects a substrate and a lead terminal, and reducing a supply amount of a conductive interconnection material required for such interconnection. Solution to the problem

[0006] A semiconductor module according to the present invention comprises: a semiconductor chip, a substrate on which the semiconductor chip is arranged, a lead terminal having a connection portion connected to the substrate by a conductive connection material, and a molding resin sealing at least the semiconductor chip, the substrate, and a portion of the lead terminal, wherein the lead terminal has a protruding portion protruding at the connection portion toward one side of the substrate. [Advantageous effects of the present invention]

[0007] According to the semiconductor module of the present invention, the portion which can increase a thickness of the conductive interconnection material is provided, and therefore, a stress applied to the conductive interconnection material connecting the substrate and the lead terminal can be reduced, and at the same time, with the formation of the protruding portion, a supply amount of the conductive interconnection material required for connecting can be reduced. Short description of drawings Fig. 1 is a plan view illustrating the internal configuration of a semiconductor module 1 according to a first embodiment. Fig. 2 is a perspective view illustrating the structure of a lead terminal 62. Fig. 3 is a view provided for describing the shape of a connecting portion 65 of the lead terminal 62. Fig. 4 is a view showing a result of thermal stress simulation using the semiconductor module 1 according to the first embodiment. Fig. 5 is a view provided for describing the shape of a connecting portion 165 of a lead terminal 162. Fig. 6 is a view showing a result of thermal stress simulation using a semiconductor module 3 according to a second embodiment. Fig. 7 is a view for describing the shape of a connecting portion 365 of a lead terminal 362 constituting a conventional semiconductor module 300. Fig. 8 is a view showing a result of thermal stress simulation using the conventional semiconductor module 300. Description of embodiments

[0008] Semiconductor modules according to the respective embodiments will be described below. In the respective embodiments described below, each constituent element having substantially the same function is indicated using the same symbol in all embodiments, and repeated description of the constituent element is omitted. The respective embodiments described below are not intended to limit the inventions recited in the claims. Furthermore, all of the various constituent elements and the combinations of these constituent elements described in the respective embodiments are not always indispensable as means for solving the problems of the present invention. (First embodiment)

[0009] The internal configuration of the semiconductor module 1 according to the first embodiment will be described below with reference to Fig. 1. As described in Fig. 1, the semiconductor module 1 according to a first embodiment includes: a plurality of semiconductor chips disposed in a molding resin (only an outer edge of the molding resin is indicated by symbol M); and lead terminals 51, 52, 53. With regard to the lead terminals 51, 52, 53, an end portion (a connecting portion) of an inner lead portion of each lead terminal is disposed inside the molding resin M, and an outer lead portion of each lead terminal is disposed outside the molding resin M.

[0010] Furthermore, the semiconductor module 1 includes four semiconductor chips (first to fourth semiconductor chips Q1 to Q4) as a plurality of semiconductor chips, and further includes lead terminals 61, 62. With such a configuration, a bridge circuit is formed in the semiconductor module 1. Regarding the lead terminals 61, 62, an end portion (connection portion) of an inner lead portion of each lead terminal is disposed within the mold resin M.

[0011] In addition to the above-mentioned constituent elements, the semiconductor module 1 further includes: first to fifth wiring patterns 10 to 50, a substrate 70, first to fourth connecting elements 81 to 84, first to fourth connecting elements for control purposes (symbols of these elements are not shown in the drawings), first to fourth connecting elements for detection purposes (symbols of these elements are not shown in the drawings), first to fourth wiring patterns 111 to 114 for control purposes, first to fourth wiring patterns 121 to 124 for detection purposes, first to fourth terminals T11 to T14 for control purposes, and first to fourth terminals T21 to T24 for detection purposes. The first to fourth wiring patterns 10 to 50 constitute portions of the substrate 70. The semiconductor module 1 may also include other constituent elements besides the above constituent elements.In the semiconductor module 1, the bridge circuit is formed such that the first semiconductor chip Q1 and the third semiconductor chip Q3 are arranged on a high side, and the second semiconductor chip Q2 and the fourth semiconductor chip Q4 are arranged on a low side.

[0012] In the semiconductor module 1, the first semiconductor chip Q1 and the third semiconductor chip Q3 are arranged line-symmetrically with respect to a center line C, and the second semiconductor chip Q2 and the fourth semiconductor chip Q4 are arranged line-symmetrically with respect to the center line C. Such a line-symmetrical arrangement relationship with respect to the center line C is also applied between the first wiring pattern 10 and the third wiring pattern 30, between the second wiring pattern 20 and the fourth wiring pattern 40, between the lead terminal 52 and the lead terminal 53, and between the lead terminal 61 and the lead terminal 62. In addition, such a line-symmetrical arrangement relationship with respect to the center line C is applied between the fifth wiring pattern 50 and the lead terminal 51.

[0013] The line terminal 51 is formed on line terminals 56, 57, which serve as input power source terminals. That is, the line terminals 52, 53 function as input power source terminals. The line terminals 61, 62 function as output power source terminals. [Structure of a line connection]

[0014] The following describes the structures of the lead terminals 52, 53, 56, 57, 61, 62. However, the structures of the connecting portions 54, 55, 58, 59, 64, 65 are substantially the same, and therefore, in this embodiment, the description will be made by taking the lead terminal 62 as an example, and the structures of the other lead terminals 52, 53, 56, 57, 61 will be omitted. Furthermore, although the connecting portions of the respective lead terminals 52, 53, 56, 57, 61, 62 are connected to the wiring patterns on the substrate 70, in the following description, the description will be made assuming that the wiring patterns also constitute portions of the substrate 70.

[0015] As in Fig. 3, the lead terminal 62 has the connecting portion 65 at a distal end thereof, and the connecting portion 65 is connected to the wiring pattern 40 via a conductive connecting material 18. In this embodiment, the conductive connecting material 18 is a solder (solder in the broad sense of the term, which is why it includes lead-free solders and the like). The connecting portion 65 has protruding portions 12a, 12b that protrude from an outer peripheral end surface 23 of the connecting portion 65 toward a surface (upper surface) of the substrate 70 on which the fourth wiring pattern 40 is formed. The protruding portions 12a, 12b are arranged to be adjacent to an edge of the connecting portion 65. The Fig. The example shown in Figure 2 illustrates an example in which two protruding portions 12a, 12b are formed in a spaced-apart manner with a predetermined distance therebetween. However, only one protruding portion 22 may be formed, as shown in Fig. 5, or three or more protruding portions may be formed at a predetermined interval (not shown in the drawing). The protruding portions 12a, 12b may be formed by press molding by applying pressing to an upper surface of the connecting portion 65. However, the method for forming protruding portions is not limited to such a method. Recessed portions 14a, 14b are each portions (by-products) formed at the time of forming the protruding portions 12a, 12b by pressing. It is preferable that a height H of the protruding portions 12a, 12b is not less than 0.1 mm and not more than one half of a plate thickness D of the connecting portion 65.

[0016] The conductive bonding material 18 in paste form is applied to the substrate 70 by coating (for example, printing or the like), the lead terminal 62 is mounted on the substrate 70, and then heat is applied to the conductive bonding material 18. Consequently, the conductive bonding material 18 is melted, so that the bonding portion 65 is bonded to the substrate 70. At this time, the conductive bonding material 18 in wet form spreads into a space formed between the protruding portion 12a and the protruding portion 12b, which are arranged adjacent to each other. [Simulation of thermal stresses]

[0017] Under a condition where the thickness of the conductive connecting material on a lower end surface of the connecting portion 65 where the protruding portions 12a, 12b are not present is set to 0.15 mm (see Fig. 3), thermal stresses were measured which were exerted on the conductive connecting material 18, which connected the lead terminal 56, the lead terminal 57, the lead terminal 52, the lead terminal 53, the lead terminal 61, and the lead terminal 62 to the substrate 70, respectively. On the other hand, in a comparative example (the prior art embodiment), thermal stresses were measured which were exerted on the conductive connecting material 348, which connected lead terminals 352, 353, 356, 357, 361, 362 to a substrate 370, which is a Fig. 8. No protruding portions were formed on the connecting portions of these lead terminals (for example, the one shown in Fig. 7). A temperature change condition for generating the thermal stresses was set from -55°C to 175°C (temperature difference: 230°C).

[0018] The simulation result for the simulation of thermal stresses in the first embodiment is shown in Fig. 4. As shown in Fig. 4, the thermal stress of 376 MPa was detected in the pipe connection 56, the thermal stress of 389 MPa was detected in the pipe connection 57, the thermal stress of 348 MPa was detected in the pipe connection 52, the thermal stress of 361 MPa was detected in the pipe connection 53, the thermal stress of 371 MPa was detected in the pipe connection 61, and the thermal stress of 390 MPa was detected in the pipe connection 62. In the simulation result (comparison result) when simulating thermal stresses in the comparison example, as shown in Fig. 8, the thermal stress of 490 MPa was detected in the lead terminal 356, the thermal stress of 485 MPa was detected in the lead terminal 357, the thermal stress of 390 MPa was detected in the lead terminal 352, the thermal stress of 418 MPa was detected in the lead terminal 353, the thermal stress of 475 MPa was detected in the lead terminal 361, and the thermal stress of 502 MPa was detected in the lead terminal 362. Consequently, it is understood that according to the configuration of the present embodiment, the thermal stresses exerted on the conductive connecting material 18 connecting the respective lead terminals 52, 53, 56, 57, 61, 62 to the substrate 70 were significantly reduced compared with the thermal stresses (see Fig. 8) applied to the conductive connecting material 348 connecting the lead terminals 352, 353, 356, 357, 361, and 362, which were arranged at the same position with respect to the substrate 370 in the conventional embodiment (the embodiment having neither the protruding portion 12a nor the protruding portion 12b), were reduced.

[0019] With the above-mentioned configuration, even if the lead terminal 62 expands or contracts due to a temperature change caused by the difference in linear expansion coefficient between the molding resin M and the lead terminal 62, a thickness (solder thickness) of the conductive connecting material 18 is increased by an amount equal to a height H of the protruding portions 12a, 12b, and therefore, the occurrence of a crack can be suppressed. Accordingly, it is possible to suppress stress exerted on the conductive connecting material 18 connecting the substrate 70 and the lead terminal 62.Compared with a case where only a thickness of the conductive connecting material 18 is increased to alleviate a stress applied to the conductive connecting material 18, a supply amount of the conductive connecting material 18 can also be slightly reduced due to the presence of the protruding portions 12a, 12b. Consequently, according to the above-mentioned configuration, a stress applied to the conductive connecting material 18 connecting the substrate 70 and the lead terminal 62 can be reduced, and at the same time, a supply amount of the conductive connecting material 18 required for connection can be reduced.

[0020] Furthermore, in a case where a width of the lead terminal is increased for the purpose of reducing inductance, a large amount of the conductive bonding material (solder) is required. However, an amount of the conductive bonding material that can be stably or safely applied to the substrate by coating is limited, and therefore, it is desirable to reduce an amount of the conductive bonding material to an appropriate level. According to the above-mentioned configuration, a supply amount of the conductive bonding material can be easily adjusted by appropriately adjusting a height and an area of ​​the protruding portion, and therefore, it is possible to achieve an advantageous effect that the degree of freedom in adjusting a supply amount of the conductive bonding material can be increased.In addition, a joining area of ​​the conductive joining material can be increased with the formation of the protruding portions, and therefore a joining strength can be easily increased. (Second embodiment)

[0021] A semiconductor module 3 according to a second embodiment differs from the semiconductor module 1 according to the first embodiment basically in that only one protruding portion 22 is formed in the semiconductor module 3 according to the second embodiment. Hereinafter, only the point that makes the semiconductor module 3 according to the second embodiment different from the semiconductor module 1 according to the first embodiment will be described, and the description of parts substantially the same as the corresponding parts in the first embodiment will be omitted. Hereinafter, the description will be made in the same manner as the above-described first embodiment by taking a lead terminal 162 as an example, and the description of the structures of other lead terminals 152, 153, 156, 157, 161 will be omitted.

[0022] As in Fig. 5, the lead terminal 162 has a connecting portion 165 at a distal end thereof, and the connecting portion 165 is connected to the wiring pattern 40 via a conductive connecting material 28. The connecting portion 165 has a protruding portion 22 protruding from an outer peripheral end surface (not indicated by reference numerals in the drawing) of the connecting portion to a surface (upper surface) of a substrate 70 on which the fourth wiring pattern 40 is formed. The protruding portion 22 may be formed by press molding by applying pressing to an upper surface of the connecting portion 165. However, the method for forming the protruding portion 22 is not limited to such a method. A recessed portion 24 is a portion (a by-product) formed at the time of forming the protruding portion 22 by pressing.It is preferable that a height H of the protruding portion 22 is not less than 0.1 mm and not more than one half of a plate thickness D of the connecting portion 65.

[0023] The conductive bonding material 28 in paste form is applied in advance to the substrate 70 by coating (for example, printing or the like), the lead terminal 162 is mounted on the substrate 70, and then heat is applied to the conductive bonding material 28. Consequently, the conductive bonding material 28 is melted, so that the bonding portion 165 is bonded to the substrate 70. At this time, the conductive bonding material 28 in wet form spreads into a space formed under an outer peripheral end surface 63 of the bonding portion 165 where the protruding portion 22 is absent. [Simulation of thermal stresses]

[0024] Thereafter, under a condition in which a thickness (solder thickness) of the conductive connecting material 28 existing between a lower end surface of the protruding portion 22 and the substrate 70 was set to 0.05 mm (see Fig. 5), and the thickness of the conductive connecting material 28 in portions of a lower end surface of the connecting portion 165 where the protruding portion 22 is not present is set to 0.15 mm (see Fig. 5), thermal stresses were measured which were exerted on the conductive connecting material 28 which connected the lead terminal 156, the lead terminal 157, the lead terminal 152, the lead terminal 153, the lead terminal 161, and the lead terminal 162 to the substrate 70, respectively. On the other hand, in a comparative example (the prior art embodiment), thermal stresses were measured which were exerted on a conductive connecting material 348 which connected lead terminals 352, 353, 356, 357, 361, and 362, which are the Fig. 8, to the substrate 370. No protruding portions were formed on the connecting portions of these lead terminals (for example, the connecting portion 365 in Fig. 7). A temperature change condition for generating thermal stress was set in substantially the same manner as in the first embodiment.

[0025] The measurement result in the simulation of thermal stresses in the second embodiment is shown in Fig. 6. As shown in Fig. 6, the thermal stress of 361 MPa was detected in the lead terminal 156, the thermal stress of 367 MPa was detected in the lead terminal 157, the thermal stress of 370 MPa was detected in the lead terminal 152, the thermal stress of 365 MPa was detected in the lead terminal 153, the thermal stress of 384 MPa was detected in the lead terminal 161, and the thermal stress of 364 MPa was detected in the lead terminal 162. Consequently, it is understood that according to the configuration of the present embodiment, the thermal stresses exerted on the conductive connecting material 28 connecting the respective lead terminals 152, 153, 156, 157, 161, and 162 to the substrate 70 were significantly reduced compared with the thermal stresses (see Fig.8) applied to the conductive connecting material 348 connecting the lead terminals 352, 353, 356, 357, 361 and 362 arranged at the same position in the conventional embodiment (comparative example) with respect to the substrate 370. [Summary of beneficial effects]

[0026] The semiconductor module according to the above-mentioned embodiment comprises: the semiconductor chip, the substrate on which the semiconductor chip is arranged, the lead terminal having a connection portion connected to the substrate by the conductive connection material, and the molding resin sealing at least the semiconductor chip, the substrate, and a portion of the lead terminal, wherein the lead terminal has a protruding portion protruding toward one side of the substrate in the connection portion.Accordingly, in the above-mentioned configuration, the portion in which the thickness of the conductive connecting material can be increased is provided, and therefore, a stress applied to the conductive connecting material connecting the substrate and the lead terminal can be reduced, and at the same time, with the formation of the protruding portion, a supply amount of the conductive connecting material required for connecting can be reduced.

[0027] In the semiconductor modules according to the above-mentioned embodiments, the lead terminal may include a plurality of protruding portions as the protruding portion. Accordingly, by appropriately adjusting the heights and widths of the plurality of protruding portions, a supply amount of the conductive connecting material can be more easily adjusted, and therefore, it is possible to achieve an advantageous effect of increasing the degree of freedom in adjusting the supply amount of the conductive connecting material. By forming the plurality of protruding portions, a connection area between the connection portion and the conductive connecting material can be enlarged, and therefore, a connection strength is increased.

[0028] In the semiconductor module according to the above-mentioned embodiment, it is preferable that the protruding height of the protruding portion protruding toward the substrate side be not less than 0.1 mm and not more than half the plate thickness of the connecting portion. The reason why the height of the protruding portion is set as described above is as follows. In a case where the height of the protruding portion is high, a large amount of a conductive connecting material is required, and in a case where the height of the protruding portion becomes excessively high, a whole gap formed between the protruding portion and the protruding portion causes the conductive connecting material to be difficult to spread by wetting.In a case where the height of the protruding portion is excessively low, it becomes difficult to ensure a thickness of the conductive connecting material, and therefore there is a possibility that stress relief becomes difficult. Accordingly, by controlling the height of the protruding portion such that the height of the protruding portion is not less than 0.1 mm and not more than half the plate thickness of the connecting portion, it is possible to achieve a beneficial effect that the conductive connecting material spreads easily by wetting.

[0029] In the semiconductor module according to the above-mentioned embodiment, it is desirable that the protruding portion be disposed so as to be adjacent to the edge of the connecting portion. In a case where the protruding portion is not adjacent to the edge, a size of the protruding portion becomes small, and therefore, an amount of the conductive connecting material required for connection is increased. However, by disposing the protruding portion so as to be adjacent to the edge of the connecting portion, a size of the protruding portion is increased, and therefore, an effect of reducing an amount of the conductive connecting material can be expected.

[0030] In the semiconductor modules according to the above-mentioned embodiments, it is desirable that the connecting portion constitute an end portion of the lead terminal. By forming the connecting portion on the end portion of the lead terminal, it is possible to arrange the protruding portion such that the protruding portion is adjacent to the edge, and therefore, the larger protrusion can be formed, thereby reducing the supply amount of the conductive connecting material.

[0031] The present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in addition to the case where the connecting portion is connected to the wiring pattern on the substrate, a case where the connecting portion is connected to the semiconductor chip is also considered. [List of symbols and reference signs] 1, 3, 300 semiconductor module 12a, 12b, 22 protruding section 14a, 14b, 24 recessed section 18, 28 conductive connecting material (solder) 51, 52, 53, 56, 57, 61, 62, 152, 153, 156, 157, 161, 162 line connection 54, 55, 58, 59, 64, 65, 154, 155, 158, 159, 164, 165 connecting section 70 Substrat Q1, Q2, Q3, Q4 semiconductor chip M Casting resin QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2021 / 117129A1

[0003]

Claims

[1] Semiconductor module, comprising: a semiconductor chip, a substrate on which the semiconductor chip is arranged, a lead terminal having a connection portion connected to the substrate by a conductive connecting material, and a molding resin sealing at least the semiconductor chip, the substrate, and a portion of the lead terminal, wherein the lead terminal has a protruding portion protruding toward one side of the substrate in the connection portion. [2] The semiconductor module according to claim 1, wherein the lead terminal has a plurality of protruding portions as the protruding portion. [3] The semiconductor module according to claim 1 or 2, wherein a protruding height of the protruding portion protruding toward the substrate side is not less than 0.1 mm and not more than one half of a plate thickness of the connecting portion. [4] The semiconductor module according to any one of claims 1 to 3, wherein the protruding portion is arranged such that the protruding portion is adjacent to an edge of the connecting portion. [5] The semiconductor module according to any one of claims 1 to 4, wherein the connecting portion is an end portion of the lead terminal.

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