Semiconductor module

Abstract

To reduce damage due to screwing of a case.SOLUTION: A semiconductor module includes a plate-shaped base, and a frame-shaped case having a bonding portion bonded to an outer peripheral portion of the base and made of a resin composition, in which an outer shape of the case in a plan view has a pair of first sides facing each other and a pair of second sides facing each other, at least two holes used for screwing to a heat dissipation member are provided at positions corresponding to the pair of second sides of the case, and the bonding portion has a plate-shaped first bonding portion extending along each of the pair of first sides. The first bonding portion overlaps the outer edge of the base in plan view, and when a thickness of the first bonding portion is T1 [m] and a length of the first bonding portion is L1 [m], a relationship of T1 <0.42 * L12 is satisfied.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] In semiconductor modules, such as power semiconductor modules, a base for heat dissipation is adhered to a case that houses a semiconductor chip, etc., as disclosed in Patent Documents 1 to 3. When the base is plate-shaped as in Patent Document 1, a heat dissipation member such as a heat sink is attached to the case by screws so as to be in close contact with the surface of the base opposite the case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-190685 [Patent Document 2] Patent Publication No. 2021-57447 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-220238 Summary of the Invention [Problem to be solved by the invention]

[0004] In its natural state, the surface of the base opposite the case may be intentionally or unintentionally convexly curved. In this case, when the heat dissipation member is fastened to the case with screws, the base deforms to fit tightly against the heat dissipation member, which places stress on the case. In conventional cases, there is concern that this stress may become excessive and damage the case.

[0005] In consideration of the above circumstances, one aspect of the present disclosure aims to reduce damage caused by screwing a case. [Means for solving the problem]

[0006] In order to solve the above problems, a semiconductor module according to a preferred embodiment of the present disclosure includes a plate-shaped base made of metal, and a frame-shaped case made of a resin composition, the frame-shaped case having an adhesive part bonded to an outer periphery of the base, the frame-shaped case having an adhesive part bonded to an outer periphery of the base, the frame-shaped case having an outer periphery made of a resin composition, the outer shape of the case in a plan view having a pair of first sides facing each other and a second side facing each other, the case having at least one hole used for screwing to a heat dissipation member at a position corresponding to each of the pair of second sides, the adhesive part having a plate-shaped first adhesive part extending along each of the pair of first sides, the first adhesive part overlapping an outer edge of the base in a plan view, and the first adhesive part satisfying the relationship T1<0.42×L1 2 Satisfy the relationship. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a plan view of a semiconductor module according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 10 is a diagram showing an example of a curved shape of the base. [Figure 4] 10A and 10B are diagrams for explaining how a heat dissipation member is attached to a semiconductor module. [Figure 5] FIG. 2 is a plan view of a case of the semiconductor module according to the first embodiment. [Figure 6] 2 is a plan view of a base of the semiconductor module according to the first embodiment. FIG. [Figure 7] 4A and 4B are explanatory diagrams illustrating the thickness and width of a first adhesive portion of the semiconductor module according to the first embodiment. [Figure 8] 5A and 5B are explanatory diagrams illustrating the thickness and width of a second adhesive portion of the semiconductor module according to the first embodiment. [Figure 9] 4A and 4B are explanatory diagrams showing the thickness and length of a first adhesive portion of the semiconductor module according to the first embodiment. [Figure 10] FIG. 4 is an explanatory diagram of the function of the first adhesive portion. [Figure 11] 10A and 10B are explanatory diagrams of a semiconductor module according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments of the present disclosure will be described below with reference to the drawings. Note that the dimensions and scale of each part in the drawings may differ from the actual dimensions and are shown schematically to facilitate understanding. Furthermore, the scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0009] 1. First embodiment 1-1. Overall configuration of semiconductor module Fig. 1 is a plan view of a semiconductor module 10 according to a first embodiment. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. The semiconductor module 10 is a power module such as an IGBT (Insulated Gate Bipolar Transistor) module. The semiconductor module 10 is used for power control in devices such as inverters or rectifiers mounted on equipment such as railway vehicles, automobiles, or household electrical appliances.

[0010] 1 and 2, a semiconductor module 10 includes a plurality of insulating substrates 20, a plurality of semiconductor chips 30, a base 40, a case 50, a plurality of external terminals 60, a plurality of wires 70, and a lid 80. Note that the lid 80 is not shown in Fig. 1. The wires 70 are not shown in Fig. 2.

[0011] Hereinafter, each part of the semiconductor module 10 will be described in order based on FIGS. 1 and 2. For convenience, the following description will be made using the mutually orthogonal X-axis, Y-axis, and Z-axis as appropriate. The Z-axis is an axis parallel to the thickness direction of the semiconductor module 10. Hereinafter, one direction along the X-axis is the X1 direction, and the direction opposite to the X1 direction is the X2 direction. One direction along the Y-axis is the Y1 direction, and the direction opposite to the Y1 direction is the Y2 direction. One direction along the Z-axis is the Z1 direction, and the direction opposite to the Z1 direction is the Z2 direction. The relationship between these directions and the vertical direction is not particularly limited and is arbitrary. Hereinafter, viewing in the direction along the Z-axis may be referred to as a "planar view."

[0012] Each of the multiple insulating substrates 20 is a substrate such as a DCB (Direct Copper Bonding) substrate or a DBA (Direct Bonded Aluminum) substrate. Of the two surfaces of each insulating substrate 20, multiple semiconductor chips 30 are mounted on one surface, and a base 40 is bonded to the other surface. In the example shown in Fig. 1, the thickness direction of each insulating substrate 20 is along the Z axis, and multiple semiconductor chips 30 are mounted on the surface of each insulating substrate 20 facing the Z1 direction, while a base 40 is bonded to the surface of each insulating substrate 20 facing the Z2 direction.

[0013] Specifically, as shown in FIG. 2, insulating substrate 20 has insulating plate 21, conductive plate 22, and conductive pattern 23.

[0014] The insulating plate 21 is an insulating plate-like member arranged so that the thickness direction is along the Z axis. The insulating plate 21 is made of ceramics such as aluminum nitride, aluminum oxide, or silicon nitride.

[0015] The conductive plate 22 is a plate-shaped conductor arranged over substantially the entire surface of the insulating plate 21 facing the Z2 direction. The conductive plate 22 is made of a metal such as copper or aluminum. The base 40 is joined to the conductive plate 22 by a joining material B1 such as solder shown in Figs. 7 and 8 described below.

[0016] The conductor pattern 23 is disposed on one surface of the insulating plate 21 and includes a conductor bonded to the semiconductor chip 30. In this embodiment, the conductor pattern 23 is disposed on the surface of the insulating plate 21 facing the Z1 direction and includes a plurality of conductors that are separated from one another. Like the conductor plate 22, the conductor pattern 23 is made of a metal such as copper or aluminum. A plurality of semiconductor chips 30 are bonded to the conductor pattern 23 with a bonding material such as solder (not shown).

[0017] In this way, the insulating substrate 20 is disposed on one surface of the base 40, and the semiconductor chip 30 is provided on the insulating substrate 20. The number of semiconductor chips 30 mounted on each insulating substrate 20 is arbitrary. Furthermore, the number of insulating substrates 20 included in the semiconductor module 10 is not limited to the example shown in FIG. 1, and may be two or less or four or more.

[0018] At least one of the multiple semiconductor chips 30 mounted on the insulating substrate 20 is a power semiconductor chip such as an IGBT. In this embodiment, the insulating substrate 20 mounts, as the semiconductor chips 30, switching elements such as IGBTs as well as control chips for controlling the operation of the power semiconductor chips. An input electrode, which is a drain electrode or a collector electrode, is provided on the back surface of the switching element. Meanwhile, an output electrode, which is a source electrode or an emitter electrode, and a control electrode, which is a gate electrode, are provided on the front surface of the switching element. Note that an element such as an FWD (Free Wheeling Diode) for commutating a load current may also be mounted on the insulating substrate 20. Furthermore, the semiconductor chip 30 serving as the control chip may be provided or omitted as necessary. Furthermore, the arrangement of the semiconductor chips 30 on the insulating substrate 20 is not limited to the example shown in FIG. 1 and may be arbitrary.

[0019] The base 40 is a plate-shaped member made of metal. Examples of the metal include copper, copper alloy, aluminum, and aluminum alloy. The base 40 has high thermal conductivity and dissipates heat from the semiconductor chip 30. The base 40 also has high electrical conductivity and is electrically connected to a reference potential such as a ground potential.

[0020] In the example shown in FIG. 1 , the thickness direction of the base 40 is along the Z axis. A plurality of insulating substrates 20 are bonded to the surface of the base 40 facing the Z1 direction. Meanwhile, a heat dissipation member 100, such as a heat dissipation fin, is bonded to the surface of the base 40 facing the Z2 direction, as indicated by the two-dot chain line in FIG. 2 . Also, when viewed along the Z axis, the base 40 has a shape having a pair of long sides extending along the X axis and a pair of short sides extending along the Y axis. Holes 41 are formed in the base 40 near each short side. The holes 41 are through-holes used to screw the heat dissipation member 100 to the base 40. The planar shape and number of the base 40 are not limited to those shown in FIG. 1 and are arbitrary. The holes 41 may be provided as needed or omitted.

[0021] The case 50 is a frame-shaped member that houses the insulating substrates 20 and the semiconductor chips 30. Here, the case 50 has a frame shape that surrounds the insulating substrates 20 and the semiconductor chips 30. The case 50 is essentially an insulator and is made of a resin composition containing a resin such as PPS (Polyphenylene Sulfide) or PBT (Polybutylene Terephthalate). In addition to the resin, the resin composition may contain an inorganic filler such as alumina or silica from the viewpoint of improving the mechanical strength or reducing the linear expansion coefficient of the case 50.

[0022] 1, the thickness direction of the case 50 is along the Z axis. The base 40 is adhered to the surface of the case 50 facing the Z2 direction. Details of the adhesion between the base 40 and the case 50 will be described with reference to FIGS. 7 and 8.

[0023] A plurality of external terminals 60 are arranged along the circumferential direction of the case 50 and pass through the case 50 .

[0024] 1, the thickness direction of case 50 is along the Z axis, and the outer shape of case 50 as viewed along the Z axis has a pair of first sides S1-1 and S1-2 extending along the X axis and a pair of second sides S2-1 and S2-2 extending along the Y axis, and is generally rectangular. Hereinafter, first sides S1-1 and S1-2 may be referred to as first side S1 without distinction, and second sides S2-1 and S2-2 may be referred to as second side S2 without distinction. In this embodiment, the length of each of the pair of first sides S1 is longer than the length of each of the pair of second sides S2.

[0025] As described above, the outer shape of the case 50 in plan view has a pair of opposing first sides S1 and a pair of opposing second sides S2. Two holes 52 and two holes 53 are provided at positions corresponding to the pair of second sides S2 of the case 50, respectively. This results in four holes 52 and four holes 53 provided in the case 50. The four holes 52 are used to screw a board (not shown) on which the semiconductor module 10 is mounted to the case 50. The four holes 53 are used to screw the heat dissipation member 100. The four holes 53 are provided at positions corresponding to the four corners of the case 50, i.e., near the four corners of the case 50. This allows the case 50 to be stably fixed to the heat dissipation member 100 by screwing. The shape of the case 50 is not limited to the example shown in FIG. 1 and may be any shape. Furthermore, the holes 52 may be provided or omitted as necessary. 1, for example, two holes 53 may be arranged at positions corresponding to the centers of the second sides S2, as in the second embodiment. As described above, the length of each of the pair of first sides S1 is longer than the length of each of the pair of second sides S2. Therefore, by providing holes 53 at positions corresponding to the second sides S2, even if the number of screw fastening points is reduced, the case 50 can be more stably fixed to the heat dissipation member 100 by screw fastening, compared to an embodiment in which the length of the first sides S1 is shorter than the length of the second sides S2.

[0026] Each of the plurality of external terminals 60 is a terminal for electrically connecting the semiconductor chip 30 to a substrate (not shown) on which the semiconductor module 10 is mounted. Here, each external terminal 60 is arranged both inside and outside the case 50 and is electrically connected to the semiconductor chip 30. The plurality of external terminals 60 are made of a metal such as copper, a copper alloy, aluminum, an aluminum alloy, or an iron alloy. Furthermore, the surfaces of the external terminals 60 may be plated with, for example, an Sn-based material.

[0027] Of the multiple external terminals 60 that the semiconductor module 10 has, two or more external terminals 60 are main terminals through which a main current flows, and the other two or more external terminals 60 are control terminals for controlling the operation of the semiconductor chip 30.

[0028] The plurality of wires 70 are a group of conductive wires made up of bonding wires for electrically connecting the plurality of external terminals 60 and the plurality of semiconductor chips 30. In the example shown in Fig. 1, the plurality of wires 70 include a plurality of wires 70 that electrically connect the plurality of external terminals 60 and the conductor patterns 23, a plurality of wires 70 that electrically connect different conductor patterns 23, and a plurality of wires 70 that electrically connect the conductor patterns 23 and the semiconductor chip 30.

[0029] The lid 80 is a plate-like member that is bonded to the surface of the case 50 facing the Z1 direction. The lid 80 is made of a resin material such as PPS (Polyphenylene Sulfide) or PBT (Polybutylene Terephthalate), similar to the case 50. The lid 80 is bonded to the case 50 with an adhesive or the like so as to seal the gap between the lid 80 and the case 50.

[0030] Here, although not shown, the space surrounded by the base 40, the case 50, and the lid 80 is filled with a potting material that covers the semiconductor chip 30. The potting material is made of, for example, a silicone resin such as silicone gel or an epoxy resin.

[0031] 1-2. Base and case FIG. 3 is a diagram showing an example of the curved shape of the base 40. FIG. 3 shows the relationship between the position in the diagonal direction and the position in the direction along the Z axis of the base 40. The diagonal direction is a direction perpendicular to the Z axis and along a line that passes through two diagonally opposite holes 53 of the four holes 53 in the case 50. In FIG. 3, the horizontal axis indicates the position in the diagonal direction based on the position of one of the two holes 53, and the vertical axis indicates the position in the direction along the Z axis of the surface of the base 40 facing the Z2 direction based on the positions in the Z axis direction of both ends in the diagonal direction of the surface of the base 40 facing the Z2 direction.

[0032] When no fastening force is applied to the heat dissipation member 100 by the screws to the case 50, the base 40 is curved in a convex shape toward the outside of the case 50, as shown in Fig. 3. Therefore, the surface of the base 40 facing the Z2 direction is also curved in a convex shape toward the mounting surface. By curving the base 40 in this manner, when thermal grease is interposed between the base 40 and the heat dissipation member 100, the thermal grease can be appropriately spread as the heat dissipation member 100 is screwed to the case 50.

[0033] Such a shape of the base 40 may be, for example, a shape that is intentionally formed, an unavoidable shape resulting from a molding method such as press-forming of the base 40, a shape resulting from a stress difference due to the bonding between the insulating substrate 20 and the base 40, or a shape resulting from a combination of two or more of these.

[0034] In this embodiment, since the insulating substrate 20 is bonded onto the base 40 as described above, stress therebetween may cause warping of the base 40. Even in this case, the effect of reducing the stress generated in the case 50 when the case 50 is fixed to the heat dissipation member 100 by screws is obtained by deformation of the adhesive portion 5, which will be described later.

[0035] FIG. 4 is a diagram illustrating the attachment of the heat dissipation member 100 to the semiconductor module 10X. FIG. 4 schematically illustrates a portion of the semiconductor module 10X. The semiconductor module 10X is configured similarly to the semiconductor module 10, except that it includes a case 50X instead of the case 50. The case 50X is configured similarly to the case 50, except that the configuration of the portion that overlaps with the base 40 in a plan view is different. Note that, for ease of explanation, FIG. 4 illustrates a portion of the case 50X with a two-dot chain line, and the deformation of the case 50X is exaggerated.

[0036] 4, when the heat dissipation member 100 is attached to the case 50X by fastening with the screws 200, the mounting surface 101 of the heat dissipation member 100 is flat, whereas the surface of the base 40 facing the Z2 direction is curved convexly toward the mounting surface 101, as described above. Therefore, as the screws 200 are tightened, the base 40 deforms to fit closely to the heat dissipation member 100, and as a result, stress is applied to the case 50X as indicated by the arrows in the figure. At this time, the thicker the portion of the case 50X that overlaps with the base 40, the greater the stress generated in that portion, which results in the case 50X being more susceptible to damage and a risk of poor insulation within the case 50X.

[0037] Therefore, in the semiconductor module 10, at least a part of the portion of the case 50 that overlaps with the base 40 is formed into a plate that is thinner than the other portions, thereby reducing damage to the case 50. The case 50 will be described in detail below.

[0038] FIG. 5 is a plan view of the case 50 of the semiconductor module 10 according to the first embodiment. As shown in FIG. 5, the case 50 has an adhesive portion 5. The adhesive portion 5 is a part of the case 50 and is a frame-shaped portion that is adhered to the outer periphery of the base 40. The thickness direction of the adhesive portion 5 is along the Z axis, and the outer periphery of the base 40 is adhered to the surface of the adhesive portion 5 facing the Z2 direction. Note that in FIG. 5, the adhesive portion 5 is shown shaded for ease of viewing, and leg portions 62 of the external terminals 60 that are arranged on the surface of the adhesive portion 5 facing the Z1 direction, as will be described later, are not shown.

[0039] The adhesive portion 5 has first adhesive portions 54-1 and 54-2 and second adhesive portions 55-1 and 55-2. Hereinafter, the first adhesive portions 54-1 and 54-2 may be referred to as the first adhesive portion 54 without distinction, and the second adhesive portions 55-1 and 55-2 may be referred to as the second adhesive portion 55.

[0040] The first adhesive portion 54-1 is a part of the case 50, and is a plate-like portion that protrudes toward the inside of the case 50 as shown in Fig. 7, and extends over a range of length L1 along the first side S1-1 as shown in Fig. 6. The first adhesive portion 54-2 is a part of the case 50, and is a plate-like portion that protrudes toward the inside of the case 50, and extends over a range of length L1 along the first side S1-2.

[0041] The second adhesive portion 55-1 is a part of the case 50, and is a plate-like portion that protrudes toward the inside of the case 50 as shown in Fig. 8, and extends over a range of length L2 along the second side S2-1 as shown in Fig. 6. The second adhesive portion 55-2 is a part of the case 50, and is a plate-like portion that protrudes toward the inside of the case 50, and extends over a range of length L2 along the second side S2-2.

[0042] Fig. 6 is a plan view of the base 40 of the semiconductor module 10 according to the first embodiment. In Fig. 6, for comparison with the base 40, the case 50 is indicated by a two-dot chain line, and the first adhesive portion 54 and the second adhesive portion 55 are indicated by dashed lines.

[0043] 6, each of the first adhesive portions 54-1, 54-2 overlaps the outer edge of the base 40 over the entire length L1 in plan view. Thus, each of the first adhesive portions 54-1, 54-2 overlaps the base 40 in plan view, and the base 40 is not present in the area outside the first adhesive portions 54-1, 54-2. This allows the deformation of the first adhesive portions 54 to reduce stress that occurs in the case 50 when the case 50 is fixed to the heat dissipation member 100 by screws.

[0044] On the other hand, each of the second adhesive portions 55-1 and 55-2 overlaps the outer edge of the base 40 over the entire length L2 in plan view. Thus, each of the second adhesive portions 55-1 and 55-2 overlaps with the base 40 in plan view, and the base 40 is not present in the area outside the second adhesive portions 55-1 and 55-2. This allows the deformation of the second adhesive portions 55 to reduce stress that occurs in the case 50 when the case 50 is fixed to the heat dissipation member 100 by screws.

[0045] FIG. 7 is an explanatory diagram of the thickness T1 and width W1 of the first adhesive portion 54 of the semiconductor module 10 according to the first embodiment. FIG. 8 is an explanatory diagram of the thickness T2 and width W2 of the second adhesive portion 55 of the semiconductor module 10 according to the first embodiment. FIG. 9 is an explanatory diagram of the thickness T1 and length L1 of the first adhesive portion 54 of the semiconductor module 10 according to the first embodiment. Note that FIG. 7 shows a cross section that crosses the first adhesive portion 54 and is perpendicular to the X-axis of the semiconductor module 10. FIG. 8 shows a cross section that crosses the second adhesive portion 55 and is perpendicular to the Y-axis of the semiconductor module 10. FIG. 9 shows a cross section that cuts longitudinally through the first adhesive portion 54 and is perpendicular to the Y-axis of the semiconductor module 10.

[0046] As shown in Figure 7, the first adhesive portion 54 is plate-shaped with its thickness direction along the Z axis, and the outer periphery of the base 40 is adhered to the surface of the first adhesive portion 54 facing the Z2 direction via adhesive B2.

[0047] As shown in Figure 8, the second adhesive portion 55 is plate-shaped with its thickness direction along the Z axis, and the outer periphery of the base 40 is adhered to the surface of the second adhesive portion 55 facing the Z2 direction via adhesive B2.

[0048] The adhesive B2 is, for example, an epoxy adhesive or a silicone adhesive.

[0049] A part of the external terminal 60 is provided on each of the surfaces of the first adhesive portion 54 and the second adhesive portion 55 facing the Z1 direction.

[0050] Specifically, the external terminal 60 is made of a metal plate bent into an L-shape. The external terminal 60 has a pin portion 61 and a leg portion 62.

[0051] The pin portion 61 is a part of the external terminal 60 and is a rod-shaped portion extending in the direction along the Z axis. The end of the pin portion 61 in the Z1 direction protrudes from the outer wall surface of the case 50. On the other hand, the end of the pin portion 61 in the Z2 direction is connected to the leg portion 62. Note that the shape of the pin portion 61 is not limited to the example shown in FIG. 1 , and for example, the tip of the pin portion 61 may be shaped so as to branch into two parts.

[0052] The leg portion 62 is a part of the external terminal 60 and is a plate-like portion for connecting one end of the wire 70. The leg portion 62 extends from the end of the pin portion 61 in the Z2 direction toward the inside of the case 50. The leg portion 62 is installed on the surface of the first adhesive portion 54 or the second adhesive portion 55 facing the Z1 direction, and has a pad portion that is exposed to the inside of the case 50. Although not shown in FIGS. 7 and 8, one end of the wire 70 is joined to the pad portion. The other end of the wire 70 is connected to the conductive pattern 23. The leg portion 62 may be installed on a surface in a portion different from the first adhesive portion 54 and the second adhesive portion 55.

[0053] 9, the first adhesive portion 54 is adhered to the base 40 over a range of length L1 via adhesive B2. Similarly, although not shown, the second adhesive portion 55 is adhered to the base 40 over a range of length L2 via adhesive B2. Note that, although not shown, the frame-shaped adhesive portion 5 is adhered to the base 40 over the entire periphery of the adhesive portion 5 via adhesive B2.

[0054] Here, when the thickness (length along the Z axis) of the first adhesive portion 54 is T1 [m] and the length (length along the X axis) of the first adhesive portion 54 is L1 [m], T1<0.42×L1 2This satisfies the relationship T2<0.42×L2. As a result, the stress generated in the portion along the first side S1 of the case 50 can be suitably reduced by the deformation of the first adhesive portion 54. Similarly, when the thickness (length along the Z axis) of the second adhesive portion 55 is T2 [m] and the length (length along the Y axis) of the second adhesive portion 55 is L2 [m], T2<0.42×L2 2 As a result, the stress generated in the portion along the second side S2 of the case 50 can be reduced by the deformation of the second adhesive portion 55.

[0055] In the illustrated example, the thickness T1 of the first adhesive portion 54 is constant throughout the entire length of the first adhesive portion 54. The thickness T2 of the second adhesive portion 55 is constant throughout the entire length of the second adhesive portion 55. The thickness of the first adhesive portion 54 may vary at least at one location in the length of the first adhesive portion 54. In other words, at least one plate surface of the first adhesive portion 54 may have an uneven surface. In this case, the thickness T1 is the average thickness of the first adhesive portion 54. Similarly, the thickness of the second adhesive portion 55 may vary at least at one location in the length of the second adhesive portion 55. In other words, at least one plate surface of the second adhesive portion 55 may have an uneven surface. In this case, the thickness T2 is the average thickness of the second adhesive portion 55.

[0056] Fig. 10 is an explanatory diagram of the function of the first adhesive portion 54. In Fig. 10, the first adhesive portion 54 is shown as a beam model with both ends fixed. Note that, although the function of the first adhesive portion 54 will be representatively described below, the function of the second adhesive portion 55 is also similar to that of the first adhesive portion 54.

[0057] Because both longitudinal ends of the first adhesive portion 54 are fixed inside the frame-shaped case 50, the first adhesive portion 54 can be represented as a beam with both ends fixed, as shown in FIG. 10 . Here, since the surface of the base 40 facing the Z2 direction is convexly curved as described above, when the heat dissipation member 100 is screwed to the case 50 using the holes 53, the center of the longitudinal direction of the first adhesive portion 54 receives a load as the surface of the base 40 facing the Z2 direction approaches a flat surface. For this reason, the both-end fixed model can be regarded as a centrally concentrated load model. Therefore, the deflection δ of the first adhesive portion 54 is expressed by the following equation (1): δ=FL1 3 / 192EI (1) In formula (1), F is the load [N], L1 is the length [m] of the first adhesive portion 54, E is the Young's modulus [Pa] of the first adhesive portion 54, and I is the second moment of area [m 4 ].

[0058] In addition, when the cross section of the first adhesive portion 54 is rectangular, the second moment of area I, the section modulus Z, and the maximum stress σ of the first adhesive portion 54 are max is expressed by the following equation (2). I=(W1×T1 3 ) / 12 Z=(W1×T1 2 ) / 6 σ max =FL / 8Z (2) In formula (2), W1 is the width of the first adhesive portion 54, and T1 is the thickness of the first adhesive portion 54.

[0059] From the above formulas (1) and (2), the thickness T1 can be simply expressed by the following formula (3). T1=(σ max L1 2 ) / (12·E·δ) (3)

[0060] From the size of a typical power module, L1 is set to 100 mm, and by taking into consideration the sum of the warp of the base 40 and the warp of the mounting surface 101 of the heat dissipation member 100 and a margin, δ is set to 1000 μm. By taking into consideration the bending strength of PPS of 150 MPa and a margin, σmax = 100 [MPa], and from the Young's modulus of PPS, E = 20 GPa. Substituting these into equation (3), the thickness T1 becomes approximately 4.17 [mm].

[0061] When a material with lower bending strength is used, it is desirable to make the thickness T1 smaller than the aforementioned value, considering that the warpage of the base 40, etc. may be greater than that described above. Furthermore, since L1 differs depending on the size of the semiconductor module 10, it is desirable to satisfy the relationship of the following formula (4). T1<0.42×L1 2 (4)

[0062] From the above, T1<0.42×L1 2 By satisfying the relationship, damage to the first adhesive portion 54 is reduced. By replacing T1 with T2 and L1 with L2, the relationship T2<0.42×L2 is also satisfied for the second adhesive portion 55. 2 By satisfying the above relationship, damage to the second adhesive portion 55 is reduced.

[0063] When the width (length along the Y-axis) of the first adhesive portion 54 is W1, it is preferable to satisfy the relationship W1 > T1. This makes it possible to suitably reduce stress generated in the portion along the first side S1 of the case 50 by deformation of the first adhesive portion 54. On the other hand, when the relationship W1 ≦ T1 is satisfied, depending on the thickness T1, etc., it may be impossible to ensure a sufficient adhesive area between the base 40 and the case 50, or depending on the constituent material of the first adhesive portion 54, it may be difficult to ensure the mechanical strength required for the first adhesive portion 54.

[0064] In the illustrated example, the width W1 of the first adhesive portion 54 is constant throughout the entire length of the first adhesive portion 54. The thickness of the first adhesive portion 54 may be different at least at one location in the length of the first adhesive portion 54. In this case, the width W1 is the average width of the first adhesive portion 54.

[0065] The length L1 of the first adhesive portion 54 is preferably 50% or more, and more preferably 60% or more, of the length of the first side S1, so that the stress generated in the portion of the case 50 along the first side S1 can be suitably reduced by deformation of the first adhesive portion 54.

[0066] When the width (length along the X-axis) of second adhesive portion 55 is W2, it is preferable to satisfy the relationship W2 > T2. This makes it possible to suitably reduce stress generated in the portion along second side S2 of case 50 by deformation of second adhesive portion 55. On the other hand, when the relationship W2 ≦ T2 is satisfied, depending on the thickness T2, etc., it may be impossible to ensure a sufficient adhesive area between base 40 and case 50, or depending on the constituent material of second adhesive portion 55, it may be difficult to ensure the mechanical strength required for second adhesive portion 55.

[0067] In the illustrated example, the width W2 of the second adhesive portion 55 is constant over the entire length L2 in the longitudinal direction of the second adhesive portion 55. The width of the second adhesive portion 55 may be different at least at one location in the longitudinal direction of the second adhesive portion 55. In this case, the width W2 is the average width of the second adhesive portion 55.

[0068] The length L2 of the second adhesive portion 55 is preferably 50% or more, and more preferably 60% or more, of the length of the second side S2, so that the stress generated in the portion of the case 50 along the second side S2 can be suitably reduced by deformation of the second adhesive portion 55.

[0069] 2. Second embodiment A second embodiment of the present disclosure will be described below. In the following exemplary embodiment, for elements whose actions and functions are similar to those of the above-described embodiment, the reference numerals used in the description of the above-described embodiment will be used, and detailed descriptions of each element will be omitted as appropriate.

[0070] 11 is an explanatory diagram of a semiconductor module 10A according to the second embodiment. The semiconductor module 10A has the same configuration as the semiconductor module 10 of the first embodiment, except that it has a base 40A instead of the base 40 and a case 50A instead of the case 50. In FIG. 11, the case 50A is indicated by a two-dot chain line to make it easier to compare the base 40A and the case 50A.

[0071] The case 50A is configured similarly to the case 50 of the first embodiment, except that the number and arrangement of the holes 53 are different and the second adhesive portion 55 is omitted. In the case 50A, the two holes 53 are arranged at positions corresponding to (near) the centers of the pair of second sides S2. As indicated by the dashed lines in the figure, the case 50A has the first adhesive portion 54, as in the first embodiment, but does not have the second adhesive portion 55. Note that, in the case 50A, the second adhesive portion 55 is omitted due to the difference in the number and arrangement of the holes 53, and other configurations are appropriately different.

[0072] On the other hand, the base 40A is configured similarly to the base 40 of the first embodiment, except for the number and arrangement of the holes 41. In the base 40A, two holes 41 are arranged at positions corresponding to (nearby) the two holes 53.

[0073] The second embodiment described above also reduces damage to the case 50A caused by screwing. Here, as described above, the two holes 53 are positioned at positions corresponding to the centers of the pair of second sides S2, so that the portions of the case 50A along the second sides S2 are less likely to be damaged by screwing. Therefore, even if the second adhesive portions 55 are omitted, damage to the case 50A caused by screwing can be reduced.

[0074] 3. Variations The present disclosure is not limited to the above-described embodiments, and various modifications are possible as described below. Furthermore, the embodiments and modifications may be combined as appropriate.

[0075] 3-1. Variation 1 In the above-described embodiment, the length of the first side S1 is longer than the length of the second side S2, but this is not limited to this embodiment, and the length of the first side S1 may be shorter than the length of the second side S2.

[0076] 3-2. Variation 2 In the above-described embodiment, an example is given in which the external terminals 60 are integrally molded into the cases 50, 50A by insert molding, but this is not limited to this embodiment, and the external terminals 60 may be inserted into the terminal holes of the cases 50, 50A after the cases 50, 50A are molded.

[0077] 3-3. Variation 3 In the above-described embodiment, the external terminal 60 has the pin portion 61 and the leg portion 62, but the present invention is not limited to this embodiment, and the shape of the external terminal 60 is arbitrary. Furthermore, the semiconductor module 10, 10A may have no external terminal 60 for control.

[0078] 4. Notes For example, the following aspects can be understood from the above embodiment and modified examples.

[0079] (Supplementary Note 1) A first aspect of a preferred example of a semiconductor module of the present disclosure includes a plate-like base made of metal, and a frame-like case made of a resin composition, the frame-like case having an adhesive part bonded to an outer periphery of the base, the frame-like case having an outer shape in a planar view having a pair of first sides facing each other and a second side facing each other, the case having at least one hole used for screwing to a heat dissipation member at a position corresponding to each of the pair of second sides, the adhesive part having a plate-like first adhesive part extending along each of the pair of first sides, the first adhesive part overlapping an outer edge of the base in a planar view, and the first adhesive part satisfying the relationship T1<0.42×L1 where T1 is a thickness [m] and L1 is a length [m]. 2 Satisfy the relationship.

[0080] In the above embodiment, the first adhesive portion, which is plate-shaped in plan view, overlaps the outer edge of the base, so that the stress generated in the case when the case is fixed to the heat dissipation member by screws can be reduced by deformation of the first adhesive portion. In particular, the thickness T1 and length L1 of the first adhesive portion are set to T1<0.42×L1. 2 Since the relationship above is satisfied, the stress generated in the portion along the first side of the case can be suitably reduced by deformation of the first adhesive portion.

[0081] (Note 2) In the second aspect, which is a preferred example of the first aspect, when the width of the first adhesive portion is W1, the relationship W1>T1 is satisfied. In this aspect, the stress generated in the portion along the first side of the case can be suitably reduced by deformation of the first adhesive portion.

[0082] (Supplementary Note 3) In a third aspect, which is a preferred example of the first or second aspect, the length of each of the pair of first sides is longer than the length of each of the pair of second sides. In this aspect, even though there are fewer screw fastening locations, the case can be more stably fixed to the heat dissipation member by screw fastening, compared to an aspect in which the length of the first sides is shorter than the length of the second sides.

[0083] (Note 4) In a fourth aspect, which is a preferred example of any of the first to third aspects, the at least one hole is two holes provided at positions corresponding to the pair of second sides. In this aspect, the case can be stably fixed to the heat dissipation member by screwing.

[0084] (Supplementary Note 5) In a fifth aspect which is a preferred example of any one of the first to fourth aspects, the adhesive portion has a plate-shaped second adhesive portion extending along each of the pair of second sides, and the second adhesive portion overlaps an outer edge of the base in a plan view. When the thickness of the second adhesive portion is T2 [m] and the length of the second adhesive portion is L2 [m], T2<0.42×L2 2 In the above embodiment, the stress generated in the portion along the second side of the case can be reduced by deformation of the second adhesive portion.

[0085] (Note 6) In the sixth aspect, which is a preferred example of the fifth aspect, when the width of the second adhesive portion is W2, the relationship W2>T2 is satisfied. In the above aspect, the stress generated in the portion along the second side of the case can be suitably reduced by deformation of the second adhesive portion.

[0086] (Supplementary Note 7) In a seventh aspect, which is a preferred example of any of the first to sixth aspects, an insulating substrate is further provided which is bonded to the base. In the above aspects, the base is prone to warping due to stress between the base and the insulating substrate. Therefore, in this aspect, a significant effect is achieved by reducing the stress generated in the case when the case is fixed to the heat dissipation member by screwing, by deformation of the adhesive portion. [Explanation of symbols]

[0087] 5...adhesive portion, 10...semiconductor module, 10A...semiconductor module, 10X...semiconductor module, 20...insulating substrate, 21...insulating plate, 22...conductor plate, 23...conductor pattern, 30...semiconductor chip, 40...base, 40A...base, 41...hole, 50...case, 50A...case, 50X...case, 51...terminal hole, 52...hole, 53...hole, 54...first adhesive portion, 54-1...first adhesive portion, 54-2...first adhesive portion , 55...second adhesive portion, 55-1...second adhesive portion, 55-2...second adhesive portion, 60...external terminal, 61...pin portion, 62...leg portion, 70...wire, 80...lid, 100...heat dissipation member, 101...mounting surface, 200...screw, B1...bonding material, B2...adhesive, S1...first side, S1-1...first side, S1-2...first side, S2...second side, S2-1...second side, S2-2...second side, T1...thickness, T2...thickness, W1...width, W2...width.

Claims

1. A plate-shaped base made of metal, a frame-shaped case having an adhesive part that is adhered to the outer periphery of the base and made of a resin composition, The outer shape of the case in a plan view has a pair of first sides facing each other and a pair of second sides facing each other, At least one hole used for screwing the heat dissipation member is provided at a position corresponding to each of the pair of second sides of the case, the adhesive portion includes a plate-shaped first adhesive portion extending along each of the pair of first sides, In a plan view, the first adhesive portion overlaps an outer edge of the base, The thickness of the first adhesive portion is T １ [m], The length of the first adhesive portion is L １ When [m] is used, T １ <0.42 x L １ ２ Satisfy the relationship of Semiconductor module.

2. The width of the first adhesive portion is W １ When W １ >T １ Satisfy the relationship of The semiconductor module according to claim 1 .

3. The length of each of the pair of first sides is longer than the length of each of the pair of second sides. The semiconductor module according to claim 1 .

4. the at least one hole is two holes provided at positions corresponding to the pair of second sides, respectively; The semiconductor module according to claim 3 .

5. the adhesive portion includes plate-shaped second adhesive portions extending along the pair of second sides, In a plan view, the second adhesive portion overlaps an outer edge of the base, The thickness of the second adhesive portion is T ２ [m], The length of the second adhesive portion is L ２ When [m] is used, T ２ <0.42 x L ２ ２ Satisfy the relationship of The semiconductor module according to claim 4 .

6. The width of the second adhesive portion is W ２ When W ２ >T ２ Satisfy the relationship of The semiconductor module according to claim 5 .

7. Further comprising an insulating substrate bonded onto the base. The semiconductor module according to claim 1 .

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