Semiconductor device

Abstract

This semiconductor device comprises: a heat sink having a flat plate-shaped part and fins protruding from the flat plate-shaped part; an insulating substrate metal-bonded to one surface of the flat plate-shaped part of the heat sink; a semiconductor element metal-bonded to the insulating substrate; a holding member bonded to a surface of the flat plate-shaped part of the heat sink opposite to the one surface by being irradiated with laser light, the holding member holding the heat sink; and a sealing resin part covering at least the insulating substrate, the semiconductor element, and a region of the one surface of the flat plate-shaped part corresponding to a region to which the holding member is bonded. The thickness of the flat plate-shaped part of the heat sink is greater in the region to which the holding member is bonded than in a region provided with the fins.

Description

Semiconductor device

[0001] The present invention relates to a semiconductor device.

[0002] For example, the semiconductor device described in Patent Document 1 includes a semiconductor module having a flat heat spreader, and a heat sink joined to the heat spreader by metal bonding.

[0003] Japanese Patent Application Laid-Open No. 2023-70910

[0004] When a semiconductor device having a semiconductor module molded with a sealing resin and a heat sink is used for a long period of time, there is a risk that the sealing resin may peel off from the heat sink. If the sealing resin peels off from the heat sink, for example, water reaches the insulating substrate in the semiconductor module and causes a short circuit, resulting in a decrease in reliability. An object of the present invention is to propose a semiconductor device capable of improving reliability.

[0005] The present invention, completed with this objective in mind, is a semiconductor device comprising: a heat sink having a flat plate-shaped portion and fins protruding from the flat plate-shaped portion; an insulating substrate metal-bonded to one surface of the flat plate-shaped portion of the heat sink; a semiconductor element metal-bonded to the insulating substrate; a holding member that is bonded to the surface of the flat plate-shaped portion of the heat sink opposite to the one surface of the flat plate-shaped portion when irradiated with laser light and holds the heat sink; and a sealing resin portion that covers at least the portion of the insulating substrate, the semiconductor element, and the portion of the flat plate-shaped portion corresponding to the bonding portion with the holding member on one surface of the flat plate-shaped portion, wherein the thickness of the portion of the flat plate-shaped portion of the heat sink at the bonding portion with the holding member is greater than the thickness of the portion where the fins are provided. Furthermore, from another perspective, the present invention is a semiconductor device comprising: a heat sink having a flat plate-shaped portion and fins protruding from the flat plate-shaped portion; an insulating substrate metal-bonded to one surface of the flat plate-shaped portion of the heat sink; a semiconductor element metal-bonded to the insulating substrate; a holding member that is bonded to the surface of the flat plate-shaped portion of the heat sink opposite to the one surface when irradiated with laser light and holds the heat sink; a sealing resin portion that covers at least the portion corresponding to the bonding portion between the insulating substrate, the semiconductor element, and the holding member on the one surface of the flat plate-shaped portion; and an intervening member interposed between the one surface of the flat plate-shaped portion and the sealing resin portion, having a thermal conductivity smaller than that of the flat plate-shaped portion. Furthermore, from another perspective, the present invention is a semiconductor device comprising: a heat sink having a flat plate-shaped portion and fins protruding from the flat plate-shaped portion; an insulating substrate metal-bonded to one surface of the flat plate-shaped portion of the heat sink; a semiconductor element metal-bonded to the insulating substrate; a holding member that is bonded to the surface of the flat plate-shaped portion of the heat sink opposite to the one surface of the flat plate-shaped portion when irradiated with laser light and holds the heat sink; and a sealing resin portion that covers at least the portion corresponding to the bonding portion between the insulating substrate, the semiconductor element, and the holding member on one surface of the flat plate-shaped portion, wherein a gap is formed between the portion of the flat plate-shaped portion of the heat sink corresponding to the bonding portion and the sealing resin portion.Furthermore, from another perspective, the present invention is a semiconductor device comprising: a heat sink having a flat plate-shaped portion and fins protruding from the flat plate-shaped portion; an insulating substrate metal-bonded to one surface of the flat plate-shaped portion of the heat sink; a semiconductor element metal-bonded to the insulating substrate; a holding member that is bonded to the surface of the flat plate-shaped portion of the heat sink opposite to the one surface when irradiated with laser light and holds the heat sink; and a sealing resin portion that covers at least the portion corresponding to the bonding portion between the insulating substrate, the semiconductor element, and the holding member on the one surface of the flat plate-shaped portion, wherein a recess is formed in the bonding portion of the flat plate-shaped portion of the heat sink, recessed from the opposite surface.

[0006] According to the present invention, it is possible to provide a semiconductor device that can improve reliability.

[0007] This figure shows an example of the external appearance of a semiconductor device according to the first embodiment. This is an example of a diagram showing the components constituting the semiconductor device according to the first embodiment disassembled. This figure shows an example of a cross-section of the semiconductor device according to the first embodiment. This figure shows an example of an integration process. This figure shows an example of a method for joining a cover to the heat sink of a semiconductor unit. This figure shows an example of a modified example of a protruding part. This figure shows an example of the schematic configuration of a semiconductor device according to the second embodiment. This figure shows an example of the schematic configuration of a semiconductor device according to the third embodiment. This figure shows an example of the schematic configuration of a semiconductor device according to the fourth embodiment.

[0008] The embodiments will be described in detail below with reference to the attached drawings. <First Embodiment> Figure 1 is a diagram showing an example of the external appearance of the semiconductor device 1 according to the first embodiment. Figure 2 is a diagram showing an example of an exploded view of the components constituting the semiconductor device 1 according to the first embodiment. Figure 3 is a diagram showing an example of a cross-section of the semiconductor device 1 according to the first embodiment. Figure 3 is a cross-sectional view of section III-III in Figure 1.

[0009] The semiconductor device 1 according to the first embodiment comprises a semiconductor module 100 and a cooling device 2 for cooling the semiconductor module 100. As shown in Figure 1, the semiconductor device 1 is mounted, for example, in an automobile with the cooling device 2 and the semiconductor module 100 joined together. Hereinafter, the direction in which the cooler 10 of the cooling device 2 and the semiconductor module 100 are stacked may be referred to as the "stacking direction". In addition, in the rectangular cooler 10, the longitudinal direction of the rectangle perpendicular to the stacking direction may be referred to as the "longitudinal direction", and the transverse direction of the rectangle may be referred to as the "transverse direction". Furthermore, in the stacking direction, the side of the cooling device 2 (lower side in Figure 1) may be referred to as the "first side", and the side of the semiconductor module 100 (upper side in Figure 1) may be referred to as the "second side".

[0010] (Cooling device 2) The cooling device 2 comprises a cooler 10, which is a cooler through which a cooling liquid can be circulated; a support member 50 that supports the cooler 10; and a connecting member 60 that connects the cooler 10 and the support member 50.

[0011] (Cooler 10) The cooler 10 comprises a plurality of heat sinks 20 (three in this embodiment), a case 30 that houses the fins 22 of the heat sinks 20 and forms a space through which the coolant flows, and a cover 40 that covers the opening of the case 30 together with the heat sinks 20. The case 30 and the cover 40 constitute a housing 15 that surrounds the plurality of fins 22 so that the coolant flows between the plurality of fins 22 of the heat sinks 20.

[0012] As shown in Figure 3, the heat sink 20 has a flat plate-shaped portion 21 and a plurality of fins 22 that protrude from the flat plate-shaped portion 21 in a direction perpendicular to the plate surface. The flat plate-shaped portion 21 has a rectangular shape when viewed from the stacking direction. The flat plate-shaped portion 21 has a first surface 211, which is the side on which the fins 22 are formed, a second surface 212, which is the side on which the fins 22 are not formed, and a protruding portion 213 at the outer periphery that protrudes from the second surface 212 on the side opposite to the fins 22. The semiconductor module 100 is bonded to the second surface 212. When viewed from the stacking direction, the protruding portion 213 is provided so as to surround the insulating substrate 110, semiconductor element 120, first joint portion 141, second joint portion 142, and third joint portion 143 of the semiconductor module 100, which will be described later.

[0013] Multiple fins 22 are formed in a portion of the central area of ​​the first surface 211, and the area surrounding the region on the first surface 211 where the fins 22 are formed is a flat surface. This flat surface surrounding the region where the fins 22 are formed may be referred to as the surrounding surface 214 below. The fins 22 can be exemplified as columnar in shape, with the direction of protrusion from the flat plate portion 21 being the stacking direction. The shape obtained by cutting the fins 22 with a plane perpendicular to the protrusion direction (hereinafter sometimes referred to as the "cross-sectional shape") can be exemplified as a quadrilateral such as a square, rectangle, or rhombus. The cross-sectional shape can also be exemplified as a circle or an ellipse. The fins 22 may also be flat. If they are flat, they may be parallel to the longitudinal direction, or they may be wavy with a portion inclined in the longitudinal direction.

[0014] The heat sink 20 may be formed by forging or machining. Furthermore, the heat sink 20 is formed from at least one of copper or aluminum. As for the aluminum material, an example would be pure aluminum of the A1000 series, such as A1100.

[0015] The case 30 is concave and has a flat bottom 31, a side portion 32 extending from the outer circumference of the bottom 31 in a direction perpendicular to the bottom 31, and a flange 33 projecting outward from the tip of the side portion 32 in a direction parallel to the bottom 31. A recess is formed by the bottom 31 and the side portion 32, and the flange 33 is formed around this recess. A circular first through hole 34 is formed at one end in the longitudinal direction of the bottom 31, and a circular second through hole 35 is formed at the other end in the longitudinal direction. The material of the case 30 can be aluminum or copper, for example.

[0016] The cover 40 is flat and has a first surface 41 which is the first side surface and a second surface 42 which is the second side surface. The cover 40 is joined to the heat sink 20 by laser welding with the fins 22 of the heat sink 20 passing through a third through hole 43 (described later) and the second surface 42 in contact with the peripheral surface 214 of the heat sink 20. The outer shape of the cover 40 is the same as the outer circumference of the flange 33 of the case 30. When the cover 40 and the flange 33 of the case 30 are joined, the cover 40 and the heat sink 20 close the opening of the recess in the case 30. Examples of methods for joining the cover 40 and the case 30 include brazing and laser welding.

[0017] The cover 40 has the same number of rectangular third through-holes 43 (three in this embodiment) formed between one end in the longitudinal direction and the other end in the longitudinal direction, through which the fins 22 of the heat sink 20 pass. The thickness (in other words, the plate thickness) around the third through-holes 43 is formed to be thinner than, for example, the thickness of one end in the longitudinal direction. In other words, recesses are formed around the third through-holes 43, recessed from the first surface 41. That is, the cover 40 has thin-walled portions 44 around each third through-hole 43. The material of the cover 40 can be aluminum or copper, for example.

[0018] (Connecting Member 60) The connecting member 60 is an elliptical columnar member in which the longitudinal direction of the case 30 is the minor axis direction and the short direction of the case 30 is the major axis direction. A circular first through hole 61 is formed in the center of the connecting member 60. The first through hole 61 has the same shape as the first through hole 34 and the second through hole 35 of the case 30 of the cooler 10. In addition, the connecting member 60 has second through holes 62 formed on both outer sides in the direction of the major axis of the first through hole 61.

[0019] The material of the connecting member 60 can be aluminum or copper, for example. The connecting member 60 is joined to the bottom 31 of the case 30. The method of joining the connecting member 60 and the case 30 can be brazing or laser welding, for example.

[0020] (Support Member 50) The support member 50 has a first space 51 recessed from the top surface at one end in the longitudinal direction and a second space 52 recessed from the top surface at the other end in the longitudinal direction. The top-side opening 51a in the first space 51 and the top-side opening 52a in the second space 52 have the same shape as the first through-hole 61 of the connecting member 60. A groove 51b into which an O-ring 55 is fitted is formed around the opening 51a of the support member 50, and a groove 52b into which an O-ring 56 is fitted is formed around the opening 52a. Furthermore, the support member 50 has female threads 51c formed on both outer sides in the longitudinal direction of the groove 51b, and female threads 52c formed on both outer sides in the longitudinal direction of the groove 52b.

[0021] The support member 50 has a communication hole formed therein that connects the first space 51 to the outside in a direction perpendicular to the stacking direction (the short side direction in Figures 1 and 2), and the first joint 53 is fitted into this communication hole. The support member 50 also has a communication hole formed therein that connects the second space 52 to the outside in a direction perpendicular to the stacking direction, and the second joint 54 is fitted into this communication hole. The material of the support member 50 can be exemplified as aluminum or copper.

[0022] (Operation of Cooling Device 2) In the semiconductor device 1 described above, the coolant that flows into the first space 51 from the first joint 53 of the support member 50 flows into the inside of the cooler 10 through the opening 51a and the first through hole 34 formed at one end in the longitudinal direction of the case 30 of the cooler 10. The coolant that has flowed into the inside of the cooler 10 travels longitudinally through the spaces between the multiple fins 22 of the heat sink 20 and between the fins 22 and the side portion 32 of the case 30, and flows out of the cooler 10 through the second through hole 35 formed at the other end in the longitudinal direction of the case 30. The coolant that has flowed out of the cooler 10 enters the second space 52 through the opening 52a formed in the support member 50 and flows out from the second joint 54. In this way, the semiconductor module 100 bonded to the cooler 10 is cooled while the coolant flows inside the cooler 10.

[0023] (Semiconductor Module 100) As shown in Figure 3, the semiconductor module 100 includes an insulating substrate 110, a semiconductor element 120, and a lead frame 130. The insulating substrate 110 is an insulating heat dissipation circuit board in which copper plates are bonded and integrated on both sides of a ceramic plate 111, which is an insulating material, and includes a first copper plate 112 provided on the first side of the ceramic plate 111 and a second copper plate 113 provided on the second side of the ceramic plate 111. Examples of bonding between the ceramic plate 111 and the first copper plate 112 and the second copper plate 113 include direct copper bonding and active metal brazing.

[0024] When viewed from the stacking direction, the ceramic plate 111 is larger than the first copper plate 112 and the second copper plate 113. Also, when viewed from the stacking direction, the ceramic plate 111 is smaller than the flat plate portion 21 of the heat sink 20. The semiconductor element 120 can be exemplified as a power semiconductor element for controlling and supplying power to an inverter or other power source.

[0025] Furthermore, the semiconductor module 100 has a first joint 141 that joins the insulating substrate 110 and the heat sink 20, a second joint 142 that joins the insulating substrate 110 and the semiconductor element 120, and a third joint 143 that joins the semiconductor element 120 and the lead frame 130. The first joint 141, the second joint 142, and the third joint 143 can be exemplified by being made of solder or sintered metal (for example, silver or copper).

[0026] Furthermore, the semiconductor module 100 includes at least an insulating substrate 110, a semiconductor element 120, a first joint 141, a second joint 142, and a sealing resin portion 150 that surrounds the third joint 143. The sealing resin portion 150 is molded using a thermosetting resin with a curing temperature of, for example, 200°C or higher. Examples of thermosetting resins include insulating resins such as epoxy resin and silicone resin.

[0027] The sealing resin portion 150 covers the end of the lead frame 130 on the third joint portion 143 side, which is one end, and exposes the tip portion, which is the other end. In addition, the sealing resin portion 150 according to this embodiment also covers the second surface 212 of the flat plate portion 21 of the heat sink 20 in order to cover the periphery of the first joint portion 141.

[0028] (Method for Manufacturing Semiconductor Device 1) An example of a method for manufacturing the semiconductor device 1 is described below. The method for manufacturing the semiconductor device 1 includes a step of integrating the semiconductor module 100 and the heat sink 20 (hereinafter sometimes referred to as the "integration step"). Hereinafter, the integrated semiconductor module 100 and heat sink 20 may be referred to as the "semiconductor unit 170". The method for manufacturing the semiconductor device 1 also includes a step of joining the cover 40 to the heat sink 20 of the semiconductor unit 170. The method for manufacturing the semiconductor device 1 also includes a step of joining the cover 40 to the case 30 and a step of joining the case 30 to the connecting member 60. The method for manufacturing the semiconductor device 1 also includes a step of attaching the semiconductor module 100, heat sink 20, case 30, cover 40 and connecting member 60 to the support member 50 by tightening the male screw of a fastening member such as a bolt, which is passed through a second through hole 62 formed in the connecting member 60, to the female screw 51c of the support member 50.

[0029] The integration process (in other words, the process for manufacturing the semiconductor unit 170) will be described in detail below. Figure 4 shows an example of the integration process. As shown in Figure 4(a), the integration process includes a first lamination step in which the heat sink 20 and the insulating substrate 110 are laminated together such that a first metal bonding material is interposed between the heat sink 20 and the insulating substrate 110. In the first lamination step, first, the first metal bonding material (for example, copper paste) is applied to the surface of the first copper plate 112 of the insulating substrate 110 opposite to the ceramic plate 111, or to the second surface 212 of the flat plate portion 21 of the heat sink 20. Then, the heat sink 20 and the insulating substrate 110 are laminated together.

[0030] Furthermore, the integration process includes a first pressurizing and heating process in which pressure and heat are applied to perform bonding with a first metal bonding material. In the first pressurizing and heating process, the heat sink 20 and the insulating substrate 110, which were laminated in the first lamination process, are pressed from the second copper plate 113 side of the insulating substrate 110, and the heat sink 20 and the insulating substrate 110 are heated. As a result, the first metal bonding material between the heat sink 20 and the insulating substrate 110 is sintered, and a first bonding portion 141 is formed between the heat sink 20 and the insulating substrate 110. Then, the heat sink 20 and the insulating substrate 110 are joined and integrated.

[0031] Furthermore, the integration process includes a second lamination step, as shown in Figure 4(b), in which the semiconductor element 120 is placed on the second copper plate 113 such that the second metal bonding material is positioned between the second copper plate 113 of the insulating substrate 110 and the semiconductor element 120. In the second lamination step, first, the second metal bonding material (for example, copper paste) is applied to the surface of the second copper plate 113 of the insulating substrate 110 that is opposite to the ceramic plate 111. Then, the semiconductor element 120 is placed on top of the metal bonding material applied to the second copper plate 113.

[0032] Furthermore, the integration process includes a second pressurizing and heating process in which pressure and heat are applied to perform bonding with a second metal bonding material. In the second pressurizing and heating process, the insulating substrate 110 and the semiconductor element 120, which were laminated in the second lamination process, are pressed from the semiconductor element 120 side, and the insulating substrate 110 and the semiconductor element 120 are heated. As a result, the second metal bonding material between the insulating substrate 110 and the semiconductor element 120 is sintered, and a second bonding portion 142 is formed between the insulating substrate 110 and the semiconductor element 120. As a result, the insulating substrate 110 and the semiconductor element 120 are bonded and integrated.

[0033] Furthermore, the integration process includes a mounting step, as shown in Figure 4(c), in which the lead frame 130 is attached to the semiconductor element 120. The mounting step can be exemplified by attaching the lead frame 130 to the semiconductor element 120 with solder. As a result of the mounting step, a third joint portion 143 is formed between the semiconductor element 120 and the lead frame 130, and the semiconductor element 120 and the lead frame 130 are integrated.

[0034] Furthermore, the integration process includes a filling process (see Figure 4(d)) in which the insulating substrate 110, heat sink 20, semiconductor element 120, and lead frame 130, which have been integrated in the previous processes, are placed in the mold 500, and resin is filled into the mold 500. The resin can be exemplified as a thermosetting resin such as epoxy resin or silicone resin. For example, in the case of silicone resin, it may be filled into the mold 500 in a liquid state.

[0035] Furthermore, the integration process includes a curing step in which the resin filled into the mold 500 is heated to harden. In the curing step, for example, after filling the mold 500 with resin, the temperature of the mold 500 can be heated to about 150°C. As a result, the resin filled into the mold 500 hardens, and a sealing resin portion 150 that covers at least the insulating substrate 110, the semiconductor element 120, the first joint portion 141, the second joint portion 142, and the third joint portion 143 is formed. The semiconductor unit 170 is manufactured in this manner.

[0036] Next, the mold 500 will be described in detail. The mold 500 shown in Figure 4(d) comprises a first mold 510 positioned on the first side in the stacking direction and a second mold 520 positioned on the second side of the first mold 510. The first mold 510 has a recess 512 formed therein, which is recessed to the first side from the first mating surface 511, which is the mating surface with the second mold 520, and into which the heat sink 20 is fitted. The first mold 510 is formed such that the first mating surface 511 is the central part in the stacking direction on the side surface 215 of the flat plate portion 21 of the heat sink 20. In addition, the opening 513 of the recess 512 is formed to have the same shape as the flat plate portion 21 of the heat sink 20.

[0037] The second mold 520 is recessed to the second side from the second mating surface 521, which is the mating surface with the first mating surface 511 of the first mold 510, and a housing portion 522 for housing the semiconductor module 100 is formed. The housing portion 522 is rectangular parallelepiped and is larger than the shapes of the insulating substrate 110, semiconductor elements 120, lead frame 130 (excluding the tip), first joint portion 141, second joint portion 142, and third joint portion 143 of the semiconductor module 100. In addition, the opening 523 of the housing portion 522 is formed to be larger than the opening 513 of the recess 512 of the first mold 510.

[0038] In the above-described arrangement process, with the heat sink 20 fitted into the recess 512 of the first mold 510, the first mating surface 511 of the first mold 510 and the second mating surface 521 of the second mold 520 are brought together. As a result, the semiconductor module 100 is housed in the housing section 522 of the second mold 520. Then, resin is filled around the semiconductor module 100 within the housing section 522 of the second mold 520. Furthermore, the resin filled in the housing section 522 is heated and hardened to form the sealing resin section 150.

[0039] When the sealing resin portion 150 is molded using the mold 500 described above, the sealing resin portion 150 covers the periphery of the first joint portion 141, the second joint portion 142, and the third joint portion 143 so that they are not exposed to the outside. The sealing resin portion 150 also covers the second surface 212 of the flat plate portion 21. The second mold 520 may be composed of multiple molds divided in the lamination direction.

[0040] Next, the process of joining the cover 40 to the heat sink 20 of the semiconductor unit 170 will be described in detail. Figure 5 shows an example of a method for joining the cover 40 to the heat sink 20 of the semiconductor unit 170. First, the cover 40 is placed on top of the heat sink 20 of the semiconductor unit 170. More specifically, as shown in Figure 5(a), the fins 22 of the heat sink 20 are passed through the third through-hole 43 of the cover 40, and the cover 40 is placed on top of the heat sink 20 so that the second surface 42 of the cover 40 contacts the peripheral surface 214 of the flat plate portion 21 of the heat sink 20.

[0041] Next, as shown in Figure 5(b), the thin-walled portion 44 of the cover 40 is irradiated with laser light 151. When the cover 40 is irradiated with laser light 151, as shown in Figure 5(c), the molten portion of the cover 40 and the molten portion of the heat sink 20 mix together, forming a welded portion 45 where the cover 40 and the heat sink 20 are joined. Note that when the cover 40 is placed on top of the heat sink 20, the positions of the thin-walled portion 44 of the cover 40 and the protruding portion 213 of the heat sink 20 are determined so that the thin-walled portion 44 of the cover 40 is located above the protruding portion 213 of the heat sink 20. In other words, when viewed from the stacking direction, the positions of the thin-walled portion 44 of the cover 40 and the protruding portion 213 of the heat sink 20 are the same. Therefore, the portion of the flat plate portion 21 of the heat sink 20 where the protruding portion 213 is provided becomes the joint portion with the cover 40. Furthermore, it can be exemplified that the size (in other words, width) of the protruding portion 213 of the heat sink 20 in the direction perpendicular to the stacking direction is the same as the size of the thin-walled portion 44 of the cover 40 in the direction perpendicular to the stacking direction.

[0042] As described above, the semiconductor device 1 comprises a heat sink 20 having a flat plate portion 21 and fins 22 protruding from the flat plate portion 21, and an insulating substrate 110 metal-bonded to a second surface 212, which is an example of one of the surfaces of the flat plate portion 21 of the heat sink 20. The semiconductor device 1 also comprises a semiconductor element 120 metal-bonded to the insulating substrate 110, and a cover 40 (an example of a holding member) that is bonded to the first surface 211 (an example of the opposite surface) of the flat plate portion 21 of the heat sink 20 when irradiated with laser light 151, and holds the heat sink 20. The semiconductor device 1 also comprises at least the insulating substrate 110, the semiconductor element 120, and a sealing resin portion 150 that covers the portion corresponding to the bonding portion with the cover 40 on the second surface 212 of the flat plate portion 21. The thickness of the flat plate portion 21 of the heat sink 20 at the bonding portion with the cover 40 is greater than the thickness of the portion where the fins 22 are provided. In other words, the flat portion 21 of the heat sink 20 has a protrusion 213 on its outer circumference, which is the joint with the cover 40. The thickness of the portion with the protrusion 213 is greater than the thickness of the portion without the protrusion 213 by the amount of the protrusion 213.

[0043] According to the semiconductor device 1 configured as described above, for example, when the thickness of the joint portion between the cover 40 in the flat plate portion 21 is the same as the thickness of the portion where the fins 22 are provided, the heat of the laser light 151 irradiated onto the cover 40 is less likely to be transmitted to the sealing resin portion 150. Hereinafter, a semiconductor device including a heat sink in which the thickness of the joint portion with the cover 40 is the same as the thickness of the portion where the fins 22 are provided may be referred to as a "semiconductor device according to the comparative example". In the semiconductor device 1, compared with the semiconductor device according to the comparative example, the sealing resin portion 150 is less likely to reach a high temperature and is difficult to melt. Even if the semiconductor device 1 is used for a long period of time, the separation between the heat sink 20 and the sealing resin portion 150 is suppressed. In particular, at the contact portion between the tip of the protruding portion 213 and the sealing resin portion 150, since it is away from the contact portion between the heat sink 20 and the cover 40, the heat generated due to the irradiation of the laser light 151 is less likely to be transmitted, and the separation is suppressed. As a result, for example, it is possible to suppress water from reaching the insulating substrate 110 in the semiconductor module 100 from the outside of the semiconductor module 100 and causing a short circuit, thereby improving the reliability of the semiconductor device 1.

[0044] FIG. 6 is a diagram showing an example of a modified example of the protruding portion 213 (see FIG. 3). The mode in which the thickness of the joint portion between the cover 40 in the flat plate portion 21 of the heat sink 20 is larger than the thickness of the portion where the fins 22 are provided is not limited to the mode described above. Instead of the protruding portion 213, the flat plate portion 21 may have a protruding portion 216 protruding from the first surface 211 to the first side on the outer peripheral portion. It can be exemplified that the position and width in the direction orthogonal to the stacking direction in which the protruding portion 216 is provided are the same as those of the protruding portion 213. Even in the configuration where the flat plate portion 21 has the protruding portion 216, it is possible to make the heat of the laser light 151 irradiated onto the cover 40 less likely to be transmitted to the sealing resin portion 150, and the reliability of the semiconductor device 1 can be improved.

[0045] Further, the flat plate portion 21 has a protruding portion (not shown) that protrudes from the first surface 211 to the first side and from the second surface 212 to the second side at the outer peripheral portion, so that the thickness of the joint portion with the cover 40 may be larger than the thickness of the portion where the fins 22 are provided. Even with such a shape, it is possible to make it difficult for the heat of the laser light 151 irradiated to the cover 40 to be transmitted to the sealing resin portion 150, and the reliability of the semiconductor device 1 can be improved.

[0046] In the semiconductor device 1, the joined body of the semiconductor unit 170 and the cover 40 is joined to the case 30 and applied to the liquid-cooled cooling device 2, but it is not particularly limited to such a mode. For example, the joined body of the semiconductor unit 170 and the cover 40 may be applied to an air-cooled cooling device that promotes heat dissipation by flowing a gas such as air between the plurality of fins 22. Further, the shape of the sealing resin portion 150 of the semiconductor unit 170 is not particularly limited. For example, the sealing resin portion 150 does not have to cover the portion on the second side of the side surface 215 of the flat plate portion 21 of the heat sink 20.

[0047] <Second Embodiment> FIG. 7 is a diagram showing an example of the schematic configuration of the semiconductor device 201 according to the second embodiment. The semiconductor device 201 according to the second embodiment is different from the semiconductor device 1 according to the first embodiment in that the heat sink 220 corresponding to the heat sink 20 is different. Further, the semiconductor device 201 is different from the semiconductor device 1 in that a low thermal conductivity member 230 having a low thermal conductivity is interposed between the heat sink 220 and the sealing resin portion 150. Hereinafter, the differences from the first embodiment will be described. The same components in the first embodiment and the second embodiment are denoted by the same reference numerals, and the detailed description thereof is omitted.

[0048] The heat sink 220 according to the second embodiment is different from the heat sink 20 according to the first embodiment in that the flat plate portion 221 corresponding to the flat plate portion 21 is different. The flat plate portion 221 is different in that it does not have the protruding portion 213 with respect to the flat plate portion 21.

[0049] The low thermal conductivity member 230 is attached so as to cover the outer periphery of the second surface 212 of the flat plate portion 221 and the second side portion of the side surface 215. The low thermal conductivity member 230 is a material with a lower thermal conductivity than the copper or aluminum material that is the material of the heat sink 220.

[0050] The low thermal conductivity member 230 can be exemplified as a heat-resistant adhesive tape having excellent heat resistance, for example, comprising a polyimide film, an acrylic or silicone adhesive, and a polyester release liner. The heat-resistant adhesive tape can be exemplified as a tape that can be used in processes for manufacturing electronic components and devices, such as temporary fixing and masking in heating processes, and for protecting and transporting film components.

[0051] If the low thermal conductivity member 230 is a heat-resistant adhesive tape, it is preferable to apply the heat-resistant adhesive tape to the outer periphery of the second surface 212 of the flat plate portion 221 and the second side portion of the side surface 215 (for example, the portion exposed from the first mold 510) before performing the filling step shown in Figure 4(d) in the integration process described with reference to Figure 4. Subsequently, when resin is filled into the mold 500 during the filling step, the low thermal conductivity member 230 is interposed between the copper or aluminum material, which is the material of the flat plate portion 221, and the sealing resin portion 150. The low thermal conductivity member 230 may be a tape molded from cloth or paper, or a vinyl tape.

[0052] Furthermore, the low thermal conductivity member 230 may be a paint. Examples of paints include paints and varnishes, which are generally liquid, solidify and adhere to the surface by the evaporation and drying of the solvent, or by the addition of a hardening agent, forming a coating film on the surface. If the low thermal conductivity member 230 is a paint, it is preferable to apply the paint to the outer periphery of the second surface 212 of the flat plate portion 221 and the second side portion of the side surface 215 (for example, the portion exposed from the first mold 510) before performing the filling process shown in Figure 4(d). After that, when the resin is filled into the mold 500 in the filling process, the low thermal conductivity member 230 is interposed between the copper or aluminum material, which is the material of the flat plate portion 221, and the sealing resin portion 150. The low thermal conductivity member 230 may also be a metal member molded from a metal material with a lower thermal conductivity than copper or aluminum.

[0053] As described above, the semiconductor device 201 is equipped with a low thermal conductivity member 230 (an example of an intervening member) which is interposed between the second surface 212 of the flat plate portion 221 and the sealing resin portion 150 and has a thermal conductivity lower than that of the flat plate portion 221. With the semiconductor device 201, since the low thermal conductivity member 230 is interposed between the heat sink 220 and the sealing resin portion 150, the heat from the laser light 151 irradiated onto the cover 40 is less likely to be transferred to the sealing resin portion 150 compared to the semiconductor device according to the comparative example. Therefore, with the semiconductor device 201, the sealing resin portion 150 is less likely to become hot compared to the semiconductor device according to the comparative example, so it is less likely to melt, and even if the semiconductor device 201 is used for a long period of time, peeling between the heat sink 220 and the sealing resin portion 150 is suppressed. As a result, for example, it is possible to suppress water from outside the semiconductor module 100 to the insulating substrate 110 inside the semiconductor module 100 and short-circuit, thus improving the reliability of the semiconductor device 201.

[0054] <Third Embodiment> Figure 8 shows an example of a schematic configuration of the semiconductor device 301 according to the third embodiment. The semiconductor device 301 according to the third embodiment differs from the semiconductor device 1 according to the first embodiment in that it has a heat sink 320 that corresponds to the heat sink 20. The differences from the first embodiment will be described below. The same reference numerals are used for the same components in the first and third embodiments, and their detailed descriptions will be omitted.

[0055] The heat sink 320 according to the third embodiment differs from the heat sink 20 according to the first embodiment in that the flat plate portion 321, which corresponds to the flat plate portion 21, is different. The flat plate portion 321 differs in that it does not have a protrusion 213 relative to the flat plate portion 21. Furthermore, the flat plate portion 321 has a recess 328 formed on the outer circumference of the second surface 212, recessed from the second surface 212. When the recess 328 is cut along a plane parallel to the stacking direction, it is rectangular in shape and can be exemplified as being formed around the entire circumference. However, the cross-sectional shape of the recess 328 is not limited to a rectangle. It may be triangular with a pointed bottom or semicircular.

[0056] In forming the recess 328 in the heat sink 320, before performing the filling process shown in Figure 4(d) in the integration process described with reference to Figure 4, the recess 328 is formed on the outer circumference of the second surface 212 of the flat plate portion 321 by, for example, forging or cutting. Then, before performing the filling process shown in Figure 4(d), the heat sink 320 is placed in the first mold 510 and the insert is fitted into the recess 328, and after the filling process is completed, the insert is removed from the recess 328.

[0057] As explained above, in the semiconductor device 301, a recess 328 is formed on the outer circumference of the flat plate portion 321 of the heat sink 320, which corresponds to the joining portion of the flat plate portion 321 of the heat sink 320, and is recessed from the second surface 212. The recess 328 functions as a gap between the heat sink 320 and the sealing resin portion 150. In other words, a gap is formed between the portion of the heat sink 320 corresponding to the joining portion of the flat plate portion 321 and the sealing resin portion 150.

[0058] In the semiconductor device 301, a gap is formed between the heat sink 320 and the sealing resin portion 150. Therefore, compared to the semiconductor device in the comparative example, the heat from the laser beam 151 irradiated onto the cover 40 is less likely to be transferred to the sealing resin portion 150. Consequently, in the semiconductor device 301, the sealing resin portion 150 is less likely to become hot compared to the semiconductor device in the comparative example, making it less likely to melt. Even if the semiconductor device 301 is used for a long period of time, delamination between the heat sink 320 and the sealing resin portion 150 is suppressed. As a result, for example, it is possible to suppress water from outside the semiconductor module 100 to the insulating substrate 110 inside the semiconductor module 100 and cause a short circuit, thereby improving the reliability of the semiconductor device 301.

[0059] The method for forming a gap between the heat sink 320 and the sealing resin portion 150 is not limited to the method described above. The shape of the recess 328 before filling with the sealing resin portion 150 may be such that the opening is narrower than the bottom, for example, a trapezoidal shape in which the width of the opening is smaller than the width of the bottom, thereby creating a shape that makes it difficult for resin to fill into the recess 328 during the filling process, thereby forming a gap.

[0060] <Fourth Embodiment> Figure 9 shows an example of a schematic configuration of the semiconductor device 401 according to the fourth embodiment. The semiconductor device 401 according to the fourth embodiment differs from the semiconductor device 1 according to the first embodiment in that it has a heat sink 420 that corresponds to the heat sink 20. The differences from the first embodiment will be described below. The same reference numerals are used for the same parts in the first and fourth embodiments, and their detailed descriptions will be omitted.

[0061] The heat sink 420 according to the fourth embodiment differs from the heat sink 20 according to the first embodiment in that the flat plate portion 421, which corresponds to the flat plate portion 21, is different. The flat plate portion 421 differs in that it does not have a protrusion 213 relative to the flat plate portion 21. Furthermore, the flat plate portion 421 has a recess 428 formed on the outer circumference of the first surface 211, recessed from the first surface 211. The recess 428 is formed when the thin-walled portion 44 of the cover 40 is irradiated with laser light 151, causing the thin-walled portion 44 of the cover 40 to melt and the flat plate portion 421 to melt, and the molten parts of the thin-walled portion 44 and the molten parts of the flat plate portion 421 to mix and form a welded portion 45.

[0062] Before the cover 40 is joined to the heat sink 420, a pre-joining recess (not shown) is formed on the outer circumference of the first surface 211 of the flat plate portion 421, recessed from the first surface 211. The pre-joining recess, when cut along a plane parallel to the lamination direction, is rectangular in shape and can be exemplified as being formed around the entire circumference. However, the cross-sectional shape of the pre-joining recess is not limited to a rectangle. In forming the pre-joining recess on the heat sink 420, the pre-joining recess is formed on the outer circumference of the first surface 211 of the flat plate portion 421 by, for example, forging or cutting, before performing the filling process shown in Figure 4(d) in the integration process described with reference to Figure 4. Alternatively, the pre-joining recess may be formed by, for example, cutting after the integration process is completed and before joining with the cover 40.

[0063] As explained above, in the semiconductor device 401, a recess 428 is formed on the outer circumference of the flat plate portion 421 of the heat sink 420, which corresponds to the joining portion of the flat plate portion 421 of the heat sink 420, and is recessed from the first surface 211. The recess 428 is formed as a result of the formation of a welded portion 45 by irradiating the portion of the thin-walled portion 44 of the cover 40 that is opposite to the pre-joining recess of the heat sink 420. Therefore, because a pre-joining recess is formed in the heat sink 420, the heat from the laser light 151 irradiated onto the cover 40 is less likely to be transferred to the heat sink 420 and the sealing resin portion 150. As a result, with the semiconductor device 401, the sealing resin portion 150 is less likely to become hot compared to the semiconductor device according to the comparative example, so it is less likely to melt, and even if the semiconductor device 401 is used for a long period of time, peeling of the heat sink 420 and the sealing resin portion 150 is suppressed. As a result, for example, it is possible to suppress water from entering the semiconductor module 100 from outside the semiconductor module 100 and short-circuiting the insulating substrate 110 inside the semiconductor module 100, thereby improving the reliability of the semiconductor device 401.

[0064] 1, 201, 301, 401... Semiconductor equipment, 2... Cooling device, 10... Cooler, 20, 220, 320, 420... Heat sink, 21, 221, 321, 421... Flat plate-shaped part, 22... Fin, 30... Case, 40... Cover, 15... Housing, 100... Semiconductor module, 110... Insulating substrate, 120... Semiconductor element, 150... Sealing resin part, 211... First surface (an example of the opposite side), 212... Second surface (an example of one side), 230... Low thermal conductivity member (an example of an intervening member), 328... Recess (an example of a void), 428... Recess

Claims

1. A semiconductor device comprising: a heat sink having a flat plate-shaped portion and fins protruding from the flat plate-shaped portion; an insulating substrate metal-bonded to one surface of the flat plate-shaped portion of the heat sink; a semiconductor element metal-bonded to the insulating substrate; a holding member that is bonded to the surface of the flat plate-shaped portion of the heat sink opposite to the one surface of the flat plate-shaped portion when irradiated with laser light, and which holds the heat sink; and a sealing resin portion that covers at least the portion of the insulating substrate, the semiconductor element, and the portion of the flat plate-shaped portion corresponding to the bonded portion with the holding member on one surface of the flat plate-shaped portion, wherein the thickness of the portion of the flat plate-shaped portion of the heat sink at the bonded portion with the holding member is greater than the thickness of the portion where the fins are provided.

2. A semiconductor device comprising: a heat sink having a flat plate-shaped portion and fins protruding from the flat plate-shaped portion; an insulating substrate metal-bonded to one surface of the flat plate-shaped portion of the heat sink; a semiconductor element metal-bonded to the insulating substrate; a holding member that is bonded to the surface of the flat plate-shaped portion of the heat sink opposite to the one surface when irradiated with laser light, and holds the heat sink; a sealing resin portion that covers at least the portion corresponding to the bonding portion between the insulating substrate, the semiconductor element, and the holding member on the one surface of the flat plate-shaped portion; and an intervening member interposed between the one surface of the flat plate-shaped portion and the sealing resin portion, having a thermal conductivity lower than that of the flat plate-shaped portion.

3. A semiconductor device comprising: a heat sink having a flat plate-shaped portion and fins protruding from the flat plate-shaped portion; an insulating substrate metal-bonded to one surface of the flat plate-shaped portion of the heat sink; a semiconductor element metal-bonded to the insulating substrate; a holding member that is bonded to the surface of the flat plate-shaped portion of the heat sink opposite to the surface of the flat plate-shaped portion when irradiated with laser light, and that holds the heat sink; and a sealing resin portion that covers at least the portion corresponding to the bonding portion between the insulating substrate, the semiconductor element, and the holding member on one surface of the flat plate-shaped portion, wherein a gap is formed between the portion of the flat plate-shaped portion of the heat sink corresponding to the bonding portion and the sealing resin portion.

4. A semiconductor device comprising: a heat sink having a flat plate-shaped portion and fins protruding from the flat plate-shaped portion; an insulating substrate metal-bonded to one surface of the flat plate-shaped portion of the heat sink; a semiconductor element metal-bonded to the insulating substrate; a holding member that is bonded to the surface of the flat plate-shaped portion of the heat sink opposite to the one surface when irradiated with laser light and holds the heat sink; and a sealing resin portion that covers at least the portion corresponding to the bonding portion between the insulating substrate, the semiconductor element, and the holding member on the one surface of the flat plate-shaped portion, wherein a recess is formed in the bonding portion of the flat plate-shaped portion of the heat sink, recessed from the opposite surface.

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