JP2022057425A - Power module and method for manufacturing power module - Google Patents

Abstract

To improve adhesion and contact between power semiconductors and heat dissipation members in power modules with multiple heat dissipation paths.SOLUTION: A power module (1) has a Hi-side power semiconductor (50) disposed on a substrate (43), a Hi-side conductive spacer (54) disposed on the substrate (43), a Hi-side conductive step absorber (25) formed over the Hi-side power semiconductor (50) and the Hi-side conductive spacer (54) and having shrinkable properties, and a Hi-side first heat spreader (20) on the Hi-side conductive step absorber (25).SELECTED DRAWING: Figure 1

Description

The present invention relates to a power module provided with a heat dissipation structure and a method for manufacturing the power module.

Power semiconductors used in power modules require high voltage and large current, so they generate heat during operation. The power module is provided with a heat dissipation mechanism for cooling the power semiconductor that generates heat in order to stabilize its operation.

For example, in Patent Document 1, a power device (semiconductor device) which is arranged on an insulating substrate having a SiN-based ceramic substrate and has electrodes on the front surface side and the back surface side, and one end thereof are connected to the front surface side of the power device. A power module comprising a graphite wiring having an anisotropic conductivity at which the other end is connected to an insulating substrate is disclosed.

The heat dissipation path of this power module is a path that transfers heat on the back side of the power device to the ceramic substrate via the electrode on the back side, and a path that transfers heat on the front side of the power device to the ceramic via the graphafite wiring. There is a path to transfer heat to the substrate. Both heat dissipation paths dissipate heat to the heat sink arranged on the back surface of the ceramic substrate through the ceramic substrate. Therefore, the high heat dissipation of the ceramic substrate is important for reducing the thermal resistance of the module.

Patent Document 2 describes a power semiconductor chip and a first conductive spacer provided on a lower carrier substrate, a second conductive spacer provided on the surface of the power semiconductor chip, and a first conductive spacer. A semiconductor package composed of a conductive element provided on a second conductive spacer is disclosed. In this semiconductor package, the conductive element and the lower carrier substrate serve as cooling members, and heat generated from the power semiconductor chip is radiated from both the front surface and the back surface of the power semiconductor chip.

Patent Document 3 discloses a power device provided on a substrate and a flip-chip power device having a metallic connection portion connected to the surface of the power device. The board and the metal connection dissipate the heat generated by the power device. Similar to Patent Document 2, Patent Document 3 dissipates heat generated from a power device from both the front surface and the back surface of the power device.

Patent Document 4 discloses a semiconductor device provided on a substrate, a heat spreader connected to the surface of the semiconductor device, and a semiconductor device provided with a heat sink connected to the heat spreader. This semiconductor device is a path for radiating heat from both sides of the semiconductor device, and a path for radiating heat to the substrate side and a path for radiating heat to the heat sink side are disclosed.

Patent Document 5 describes a wiring board, a plurality of semiconductor components mounted on the wiring board, a first heat conductive member arranged on the semiconductor component, and a solid buffer arranged on the first heat conductive member. A member (heat spreader), a second heat conductive member arranged on the cushioning member and having flexibility, and a heat radiating member (heat sink) thermally connected to a plurality of cushioning members via the second heat conductive member. The semiconductor device having is disclosed. In this semiconductor device, the flexible second heat conductive member is elastically deformed by the pressing force when the wiring board and the heat radiating member are fastened. By elastically deforming the second conductive member, the gap between the cushioning member having a different height and the heat radiating member is filled and thermally connected. This makes it possible to dissipate heat evenly even when the height of the semiconductor component caused by an uncertain cause such as the amount of solder when mounting the semiconductor component is not constant.

Japanese Unexamined Patent Publication No. 2019-71399 U.S. Publication No. 2020/0035579 U.S. Pat. No. 10,720,380 Japanese Patent No. 6711098 Japanese Unexamined Patent Publication No. 2020-9989

By using a member having high heat dissipation such as a ceramic substrate for the substrate as in Patent Document 1, it is possible to sufficiently dissipate heat generated from the power module and cool the power module. However, since such a substrate having high heat dissipation is expensive, it has been a factor of increasing the manufacturing cost of the power module.

In order to cool the power module without using a substrate having high heat dissipation, it is conceivable to increase the number of paths for dissipating heat generated from the power module as in Patent Documents 2 and 3. As a result, it is possible to obtain the same cooling effect as when a substrate having high heat dissipation is used. However, the specific structure that dissipates heat from both sides of the power module is not disclosed in Patent Documents 2 and 3.

Patent Document 4 discloses a specific structure for a path that dissipates heat from both sides of a power module. However, when the power semiconductor is mounted on the substrate, an unintended step may occur in the mounted power semiconductor due to the variation and inclination of the solder thickness. When such an unintended step occurs in the power semiconductor, the contact thermal resistance between the heat radiating member for radiating heat generated from the power semiconductor and the power semiconductor decreases, and it becomes difficult to obtain the cooling effect of the power semiconductor. Challenges arise.

By using the flexible second heat conductive member as in Patent Document 5, it is possible to maintain thermal connectivity when the heights of a plurality of semiconductor parts are different. However, the second heat conductive member is arranged at a position away from the power semiconductor, and when the power semiconductor is mounted on the substrate, an unintended step caused in the mounted power semiconductor due to the variation and inclination of the solder thickness. Cannot be absorbed. Therefore, the adhesion and contactability between the power semiconductor and the heat radiating member are lowered, and the contact thermal resistance is lowered.

One aspect of the present invention is to provide a power module having a plurality of heat dissipation paths and having improved adhesion and contact between the power semiconductor and the heat dissipation member.

In order to solve the above problems, the power module according to one aspect of the present invention dissipates heat from the power semiconductor arranged on the substrate, the conductive spacer arranged on the substrate, and the heat generated from the power semiconductor. In order to dissipate heat generated by the power semiconductor through the conductive step absorbing portion formed on the power semiconductor and the conductive spacer and having shrinkage, and the conductive step absorbing portion. A first heat spreader provided on the conductive step absorbing portion is provided.

In order to solve the above problems, the method for manufacturing a power module according to one aspect of the present invention includes a power module substrate including a power semiconductor arranged on the substrate and a conductive spacer arranged on the substrate. A power module substrate forming step to be formed, a conductive step absorbing portion provided to dissipate heat generated from the power semiconductor and having shrinkage, and a first heat spreader provided on the conductive step absorbing portion. The heat dissipation unit forming step of forming the heat dissipation unit including the above, and the substrate, the power semiconductor, the conductive spacer, the conductive step absorbing portion, and the lower side of the substrate of the housing accommodating the first heat spreader. A housing joining step of joining the lower housing to be formed and the upper housing arranged on the upper side of the substrate so that the power semiconductor and the conductive spacer are pressed toward the conductive step absorbing portion. Including.

According to one aspect of the present invention, in a power module having a plurality of heat dissipation paths, it is possible to provide a power module having improved adhesion and contact between a power semiconductor and a heat dissipation member.

It is sectional drawing of the power module which concerns on Embodiment 1 of this invention. It is sectional drawing of the heat radiation unit which concerns on Embodiment 1 of this invention. It is sectional drawing of the power module substrate which concerns on Embodiment 1 of this invention. It is a figure which shows the heat dissipation path of the power module which concerns on Embodiment 1 of this invention. It is a figure which shows the process of connecting a heat dissipation unit and a power module board which concerns on Embodiment 1 of this invention. It is sectional drawing and bottom view of the heat dissipation unit which concerns on Embodiment 1 of this invention. It is sectional drawing and plan view of the power module substrate which concerns on Embodiment 1 of this invention. It is sectional drawing, bottom view and plan view of the state which the upper housing is joined to the heat radiation unit which concerns on Embodiment 1 of this invention, and is the plan view of the upper housing. FIG. 3 is a cross-sectional view and a bottom view of a state in which a heat dissipation unit, a power module board, and an upper housing according to the first embodiment of the present invention are joined. It is sectional drawing, bottom view and plan view of the power module which concerns on Embodiment 1 of this invention. It is sectional drawing of the state which attached the heat sink to the power module which concerns on Embodiment 1 of this invention. It is sectional drawing of the power module which concerns on Embodiment 2 of this invention. It is sectional drawing of the power module which concerns on Embodiment 3 of this invention. It is sectional drawing of the power module which concerns on Embodiment 4 of this invention. It is sectional drawing of the power module which concerns on Embodiment 5 of this invention.

[Embodiment 1]
Hereinafter, one embodiment of the present invention will be described in detail. For convenience of explanation, the drawings will be described with the upper side of the paper surface as the upper side and the lower side of the paper surface as the lower side.

FIG. 1 is a cross-sectional view of the power module 1 according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of the heat dissipation unit 10 according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of the power module substrate 40 according to the first embodiment of the present invention. FIG. 4 is a diagram showing a heat dissipation path of the power module according to the first embodiment of the present invention. FIG. 5 is a diagram showing a process of connecting the heat dissipation unit 10 and the power module substrate 40 according to the first embodiment of the present invention.

In this embodiment, a power module including two or more power semiconductors, which is described as a half-bridge type power module having a power semiconductor on the Hi side and a power semiconductor on the Lo side.

As shown in FIG. 1, the power module 1 includes a heat dissipation unit 10, a power module board 40, and a housing 70. The housing 70 accommodates the heat dissipation unit 10 and the power module board 40. The housing 70 has an upper housing 71 and a lower housing 75. The upper housing 71 is provided with a through hole 73 for the screw 79 (FIG. 11). The lower housing 75 is provided with a through hole 77 for the screw 79 (FIG. 11). The upper housing 71 and the lower housing 75 are joined so as to press the heat dissipation unit 10 against the power module board 40.

As shown in FIGS. 1 and 2, the heat dissipation unit 10 includes a second heat spreader 12, an insulating heat spread sheet 14, a first heat spreader 20 on the Hi side, a conductive step absorbing portion 25 on the Hi side, and a first Lo side. It is composed of a heat spreader 30 and a Lo-side conductive step absorbing portion 35.

The second heat spreader 12 dissipates heat generated from the power semiconductors 50 and 60 to the outside of the power module 1. The second heat spreader 12 is made of a material having high thermal conductivity. For example, Al, Cu and the like are used. The second heat spreader 12 is provided with a screw hole 13 into which the screw 79 is screwed. The second heat spreader 12 is attached to the housing 70 by screwing the screw 79 into the screw hole 13.

The insulating heat dissipation sheet 14 is adhered to the second heat spreader 12. For the insulating heat radiating sheet 14, an insulating material having high thermal conductivity is used. The Hi-side first heat spreader 20 and the Lo-side first heat spreader 30 are adhered to the insulating heat-dissipating sheet 14. In other words, the first heat spreaders 20 and 30 are connected to the second heat spreader 12 via a common insulating heat dissipation sheet 14.

The first heat spreaders 20 and 30 are made of a material having high thermal conductivity. For example, Al, Cu and the like. The first heat spreader includes a Hi-side first heat spreader 20 corresponding to the Hi-side power semiconductor 50 and a Lo-side first heat spreader 30 corresponding to the Lo-side power semiconductor 60. The Hi-side first heat spreader 20 and the Lo-side first heat spreader 30 are adhered to the insulating heat-dissipating sheet 14 at intervals from each other. In other words, the first heat spreader is provided for each power semiconductor. Therefore, it is possible to insulate the potentials on the circuit side of the power semiconductors 50 and 60 connected to the circuits having different potentials formed on the power module substrate 40.

The conductive step absorbing portions 25 and 35 are made of a highly heat-dissipating sheet having adhesiveness and conductivity and a member having conductivity and shrinkage such as graphite. The Hi-side conductive step absorbing portion 25 is adhered to the Hi-side first heat spreader 20. The Lo-side conductive step absorbing portion 35 is adhered to the Lo-side first heat spreader 30.

As shown in the cross section 1000 of FIG. 5, the height between the members is increased due to the variation in the thickness of the solder when connecting the power semiconductors 50 and 60 and the conductive spacers 54 and 64 to the substrate 43 by the solder, or the dimensional tolerance of the members. There may be variations in the solder. However, as shown in the cross section 1010 of FIG. 5, the conductive step absorbing portions 25 and 35 are pressed by the power semiconductors 50 and 60 and the conductive spacers 54 and 64 when the upper housing 71 and the lower housing 75 are joined. Causes contraction and deformation. This makes it possible to improve the contact and adhesion between the step absorbing portions 25 and 35 and the power semiconductors 50 and 60 and the conductive spacers 54 and 64.

As shown in FIG. 3, the power module substrate 40 is composed of a substrate 43, power semiconductors 50 and 60, conductive spacers 54 and 64, and buffer spacers 58 and 68.

The substrate 43 is an insulating substrate formed of, for example, a resin. A circuit pattern is formed on the surface on the side where the power semiconductors 50 and 60 are provided. The substrate 43 is formed with a through hole 45 for the screw 79. A terminal 47 connected to another member is formed at one end of the substrate 43. Further, module circuit components such as a gate driver, a resistor, and a capacitor (not shown) are also mounted on the substrate 43.

Power semiconductors 50 and 60 are provided on the substrate 43. The power semiconductors 50 and 60 are surface mount type thin packages or bare chips. The bare chip has better heat dissipation because there is no thermal resistance in the package. The power semiconductors 50 and 60 have a heat radiating surface that conducts generated heat to the outside and a mounting surface on which electrodes are formed. In the drawing, the upper side is the heat dissipation surface and the lower side is the mounting surface. In other words, the heat dissipation surface is the surface that comes into contact with the conductive step absorbing portions 25 and 35, and the mounting surface is the surface that is connected to the substrate 43.

The electrodes 52 and 62 formed on the mounting surfaces of the power semiconductors 50 and 60 are connected to the circuit pattern of the substrate 43 by soldering.

The heat dissipation surface of the Hi-side power semiconductor 50 is in contact with the Hi-side conductive step absorbing portion 25. The heat dissipation surface of the Lo-side power semiconductor 60 is in contact with the Lo-side conductive step absorbing portion 35.

Conductive spacers 54 and 64 are provided in the vicinity of the power semiconductors 50 and 60. The conductive spacers 54 and 64 have conductivity and are formed of a material having high thermal conductivity. In the manufacture of the power module substrate 40, the surface of the conductive spacers 54 and 64 in contact with the conductive step absorbing portions 25 and 35 is about the same as the surface of the power semiconductors 50 and 60 in contact with the conductive step absorbing portions 25 and 35. It is installed so as to be at the height of.

The Hi-side conductive spacer 54 is soldered to an intermediate potential connection portion 56 connected to the intermediate potential of the circuit pattern formed on the substrate 43. The Lo-side conductive spacer 64 is soldered to a ground potential connection portion 66 connected to the ground (GND) of the circuit pattern formed on the substrate 43.

The Hi-side conductive spacer 54 is provided so as to be in contact with the Hi-side conductive step absorbing portion 25. The Lo-side conductive spacer 64 is provided so as to be in contact with the Lo-side conductive step absorbing portion 35.

The cushioning spacers 58 and 68 are located between the substrate 43 and the first heat spreaders 20 and 30, and are provided so as to support the first heat spreaders 20 and 30. The cushioning spacers 58 and 68 are made of a material having insulating and shrinkable properties. The Hi-side cushioning spacer 58 supports the Hi-side first heat spreader 20. The Lo-side buffering spacer 68 supports the Lo-side first heat spreader 30.

By supporting the first heat spreaders 20 and 30, the cushioning spacers 58 and 68 can disperse the stress applied to the power semiconductors 50 and 60 and widen the parallelism between the substrate 43 and the first heat spreaders 20 and 30. Can be kept at. As a result, the area of the first heat spreaders 20 and 30 provided for each of the power semiconductors 50 and 60 can be increased. That is, the heat generated from the power semiconductors 50 and 60 can be diffused over a wide range, and the first heat spreaders 20 and 30 and the conductive step absorbing portions 25 and 35, or the conductive step absorbing portions 25 and 35 and the power semiconductor 50. , 60 and the adhesiveness and adhesion to the conductive spacers 54 and 64 can be improved, and the contact thermal resistance can be kept low and stabilized.

As described above, the power module 1 includes the Hi-side or Lo-side power semiconductors 50 and 60 arranged on the substrate 43, the Hi-side or Lo-side conductive spacers 54 and 64 arranged on the substrate 43, and the Hi-side. Alternatively, in order to dissipate heat generated from the Lo-side power semiconductors 50 and 60, the Hi-side or Lo-side power semiconductors 50 and 60 and the Hi-side or Lo-side conductive spacers 54 and 64 are formed on the Hi and have shrinkage. To diffuse and dissipate heat generated by the Hi-side or Lo-side power semiconductors 50 and 60 via the side or Lo-side conductive step-absorbing portions 25 and 35 and the Hi-side or Lo-side conductive step-absorbing portions 25 and 35. , Hi-side or Lo-side first heat spreaders 20 and 30 provided on the Hi-side or Lo-side conductive step absorbing portions 25 and 35.

The power module 1 includes the Hi-side or Lo-side conductive step absorption portions 25 and 35, the Hi-side or Lo-side power semiconductors 50 and 60, the Hi-side or Lo-side conductive spacers 54 and 64, and the Hi-side or Lo-side conductive spacers 54 and 64, and the Hi-side or Lo-side conductive spacers 54 and 64. The Hi side or Lo arranged on the substrate 43 to support the Hi side or Lo side first heat spreaders 20 and 30 in order to reduce the contact thermal resistance between the side first heat spreaders 20 and 30 respectively. Further, side buffering spacers 58 and 68 are provided.

Further, the power module 1 dissipates heat generated from the Lo-side power semiconductor 60 arranged on the substrate 43, the Lo-side conductive spacer 64 arranged on the substrate 43, and the Lo-side power semiconductor 60. The heat generated by the Lo-side power semiconductor 60 via the Lo-side conductive step-absorbing portion 35 formed on the Lo-side power semiconductor 60 and the Lo-side conductive spacer 64 and having shrinkage, and the Lo-side conductive step-absorbing portion 35. The Lo-side first heat spreader 30 is provided on the Lo-side conductive step absorption unit 35 so as to be insulated from the Hi-side first heat spreader 20, and the Hi-side power semiconductor 50 and the Lo-side power are provided in order to diffuse and dissipate heat. In order to further diffuse and dissipate the heat generated by the semiconductor 60, a second heat spreader 12 provided on the first heat spreader 20 on the Hi side and the first heat spreader 30 on the Lo side is further provided.

In the power module 1, the Hi-side power semiconductor 50 is electrically connected to the intermediate potential connection portion 56 provided on the substrate 43 via the Hi-side conductive step absorbing portion 25 and the Hi-side conductive spacer 54. The Lo-side power semiconductor 60 is electrically connected to the ground potential connection portion 66 provided on the substrate 43 via the Lo-side conductive step absorbing portion 35 and the Lo-side conductive spacer 64.

The power module 1 includes a substrate 43, a Hi-side or Lo-side power semiconductor 50, 60, a Hi-side or Lo-side conductive spacer 54, 64, a Hi-side or Lo-side conductive step absorption portion 25, 35, and a Hi-side or Lo-side conductive step absorbing portion 25, 35. A housing 70 for accommodating the side first heat spreaders 20 and 30 is further provided, and the housing 70 includes a lower housing 75 arranged on the lower side of the board 43 and an upper housing 71 arranged on the upper side of the board 43. The lower housing 75 and the upper housing 71 are the Hi-side or Lo-side power semiconductors 50 and 60, and the Hi-side or Lo-side conductive spacers 54 and 64 are the Hi-side or Lo-side conductive step absorption portions. They are joined so as to be pressed toward 25 and 35.

The heat dissipation path of the power module 1 will be described with reference to FIG. The power module 1 has three heat dissipation paths for releasing heat generated from the power semiconductors 50 and 60 to the outside. The first heat dissipation path R1 is a path for radiating heat from the mounting surface of the power semiconductors 50 and 60 to the substrate 43 side via the electrodes 52 and 62. The second heat dissipation path R2 is a path for radiating heat from the heat dissipation surface of the power semiconductors 50 and 60 to the substrate 43 side via the conductive step absorbing portions 25 and 35 and the conductive spacers 54 and 64. The third heat dissipation path R3 is a path that dissipates heat from the heat dissipation surface of the power semiconductors 50 and 60 to the second heat spreader 12 side via the first heat spreaders 20 and 30 and the insulating heat dissipation sheet 14. The heat generated from the power semiconductors 50 and 60 is mainly transmitted to the third heat dissipation path R3 and dissipated to the outside. Since heat is dispersed in these three heat dissipation paths, it is possible to manufacture an inexpensive power module that does not require an expensive high heat dissipation substrate such as a ceramic substrate or a thick copper substrate. Further, if an expensive high heat dissipation substrate such as a ceramic substrate or a thick copper substrate is used in combination, the heat generated from the power module can be dissipated more sufficiently to cool the power module.

Next, the method of manufacturing the power module 1 in the first embodiment will be described.

A method of manufacturing the heat dissipation unit 10 will be described with reference to FIG. FIG. 6 includes a cross section 1020 and a lower surface 1030 of the heat dissipation unit 10 according to the first embodiment. As shown in the cross section 1020 of FIG. 6, first, the insulating heat radiating sheet 14 is adhered to the surface of the second heat spreader 12 opposite to the surface that dissipates heat to the outside. Both sides of the insulating heat radiating sheet 14 have adhesiveness. Next, the first heat spreaders 20 and 30 are bonded to the insulating heat radiating sheet 14 bonded to the second heat spreader 12. Next, the conductive step absorbing portions 25 and 35 are bonded to the first heat spreaders 20 and 30 bonded to the insulating heat dissipation sheet 14.

As shown in the lower surface 1030 of FIG. 6, the first heat spreaders 20 and 30 are adhered so as to fit within the region where the insulating heat dissipation sheet 14 is provided. The conductive step absorbing portions 25 and 35 are adhered to the conductive step absorbing portions 25 and 35 so as to fit within the region where the first heat spreaders 20 and 30 are provided.

A method of manufacturing the power module substrate 40 will be described with reference to FIG. 7. FIG. 7 includes a cross section 1040 and a flat surface 1050 of the power module substrate 40 according to the first embodiment. As shown in the cross section 1040 of FIG. 7, the power semiconductors 50 and 60 and the conductive spacers 54 and 64 are mounted on the substrate 43 on which the circuit pattern is formed. The circuit pattern of the substrate 43 and the electrodes 52 and 62 of the power semiconductors 50 and 60 are connected by soldering. By soldering, the conductive spacers 54 and 64 are connected to the intermediate potential connection portion 56 and the ground potential connection portion 66, respectively. The cushioning spacers 58 and 68 are adhered to the substrate 43.

The positional relationship between the member of the heat dissipation unit 10 and the member of the power module substrate 40 will be described with reference to the plane 1050 of FIG. The broken line shown on the plane 1050 in FIG. 7 indicates the position corresponding to the conductive step absorbing portions 25 and 35. The broken line region B1 indicates a position corresponding to the Hi-side conductive step absorbing portion 25. The area B2 of the broken line indicates the position corresponding to the Lo-side conductive step absorbing portion 35. Further, the alternate long and short dash line described indicates the position corresponding to the first heat spreaders 20 and 30. The region A1 indicates a position corresponding to the first heat spreader 20 on the Hi side. The region A2 indicates a position corresponding to the first heat spreader 30 on the Lo side.

As shown in the plane 1050 of FIG. 7, the power semiconductors 50 and 60 and the conductive spacers 54 and 64 are arranged on the substrate 43 so as to fit in the regions B1 and B2. The cushioning spacers 58 and 68 are arranged so as to fit within the regions A1 and A2. The buffer spacers 54 and 64 may be arranged so as to overlap at least a part of the regions A1 and A2.

Next, a method of connecting the housing 70, the heat dissipation unit 10, and the power module board 40 will be described with reference to FIGS. 8 to 10. FIG. 8 shows a cross section 1060, a lower surface 1070 and a flat surface 1080 in a state where the upper housing 71 is joined to the heat dissipation unit 10 according to the first embodiment of the present invention, and a flat surface 1090 of the upper housing 71. FIG. 9 shows a cross section 2000 and a flat surface 2010 in a state where the heat dissipation unit 10, the power module substrate 40, and the upper housing 71 according to the first embodiment are joined. FIG. 10 is a cross section 2020, a lower surface 2030, and a plane 2040 of the power module 1 according to the first embodiment.

As shown in FIG. 8, first, the upper housing 71 is temporarily bonded to the heat dissipation unit 10. As shown in the cross section 1060 of FIG. 8, the position of the screw hole 13 of the second heat spreader 12 and the through hole 73 of the upper housing 71 are aligned, and the heat radiation unit 10 is overlapped from above the upper housing 71. And the upper housing 71 are temporarily bonded.

Next, as shown in FIG. 9, the power module board 40 and the upper housing 71 are temporarily bonded. The through holes 45 provided in the board 43 and the through holes 73 of the upper housing 71 are aligned with each other, and the power module board 40 is overlapped from the lower side of the upper housing 71. At this time, as shown in the plane 2010 of FIG. 9, the power semiconductors 50 and 60 and the conductive spacers 54 and 64 are arranged at positions corresponding to the conductive step absorbing portions 25 and 35. The cushioning spacers 58 and 68 are arranged at positions corresponding to the first heat spreaders 20 and 30.

Then, as shown in FIG. 10, the through hole 45 of the substrate 43 and the through hole 77 of the lower housing 75 are matched, and the upper housing 71 and the lower housing 75 are joined. Finally, the power semiconductors 50 and 60 are sealed with the resin 87.

At the time of joining the upper and lower housings 71 and 75, the heat dissipation unit 10 and the power module substrate 40 are pressed in a direction approaching each other. At this time, the conductive step absorbing portions 25 and 35 shrink and deform in a form that absorbs the variation in the thickness of the solder and the inclination of the power semiconductors 50 and 60. This makes it possible to improve the contact and adhesion between the conductive step absorbing portions 25 and 35 and the power semiconductors 50 and 60 and the conductive spacers 54 and 64.

Further, the cushioning spacers 58 and 68 are pressed against the first heat spreaders 20 and 30 and the substrate 43 and contract. The first heat spreaders 20 and 30 are pressed toward the second heat spreader 12 by the repulsive force of the contracted buffer spacers 58 and 68. As a result, the first heat spreaders 20 and 30 can maintain parallelism with the substrate 43.

[First modification]
The power module 2 shown in FIG. 11 is a first modification of the above-described first embodiment. As in this modification, a heat sink 80 may be provided on the second heat spreader 12, and heat may be dissipated to the outside by the heat sink 80. The heat sink 80 is provided with a screw hole. By fastening the heat sink 80 and the second heat spreader 12 with the screws 79, the second heat spreader 12 and the heat sink 80 come into contact with each other. As a result, the heat generated from the power semiconductors 50 and 60 is transferred to the heat sink 80 via the second heat spreader 12.

[Embodiment 2]
Embodiment 2 of the present invention will be described below with reference to FIG. For convenience of explanation, the same reference numerals are given to the members having the same functions as the members described in the above-described embodiment, and the description thereof will not be repeated. In the second embodiment, the cushioning spacers 58 and 68 of the first embodiment are not provided, and a part of the inner wall of the upper housing 71 is projected so as to come into contact with the first heat spreaders 20 and 30. Is a feature.

FIG. 12 is a cross-sectional view of the power module 3 according to the second embodiment of the present invention. The upper housing 71 is provided with a first heat spreader support portion 74 that projects inward from a part of the inner wall. The first heat spreader support portion 74 is provided so as to come into contact with the first heat spreaders 20 and 30, respectively. The first heat spreader support portion 74 comes into contact with the lower surfaces of the first heat spreaders 20 and 30 when the heat dissipation unit 10 is temporarily bonded to the upper housing 71. The lower surface of the first heat spreaders 20 and 30 is a surface connected to the heat dissipation surface of the power semiconductors 50 and 60 and is a surface facing the substrate 43. As a result, the first heat spreader support portions 74 support the first heat spreaders 20 and 30.

As described above, the power module 3 further includes a substrate 43, power semiconductors 50 and 60, conductive spacers 54 and 64, conductive step absorbing portions 25 and 35, and a housing 70 for accommodating the first heat spreaders 20 and 30. The housing 70 has a lower housing 75 arranged on the lower side of the substrate 43 and an upper housing 71 arranged on the upper side of the board 43.

The upper housing 71 reduces the contact thermal resistance between the conductive step absorbing portions 25 and 35 and the power semiconductors 50 and 60, the conductive spacers 54 and 64, and the first heat spreaders 20 and 30, respectively. Therefore, it has a first heat spreader support portion 74 (protruding support portion) that projects in parallel with the substrate 43 so as to support the first heat spreaders 20 and 30.

[Embodiment 3]
Embodiment 3 of the present invention will be described below with reference to FIG. For convenience of explanation, the same reference numerals are given to the members having the same functions as the members described in the above-described embodiment, and the description thereof will not be repeated. The third embodiment is characterized in that a heat sink 80 is provided on the insulating heat dissipation sheet 14 instead of the second heat spreader 12.

FIG. 13 is a cross-sectional view of the power module 4 according to the third embodiment of the present invention. The heat radiating unit 10A is composed of a heat sink 80, an insulating heat radiating sheet 14, first heat spreaders 20 and 30, and conductive step absorbing portions 25 and 35. The heat sink 80 is provided with a screw hole into which the screw 79 is screwed. An insulating heat radiating sheet 14 is adhered to a surface of the heat sink 80 opposite to the surface that dissipates heat to the outside.

The heat dissipation unit 10A, the housing 70, and the power module board 40 are fastened by being fastened with the screws 79.

[Embodiment 4]
Embodiment 4 of the present invention will be described below with reference to FIG. For convenience of explanation, the same reference numerals are given to the members having the same functions as the members described in the above-described embodiment, and the description thereof will not be repeated. The fourth embodiment is characterized in that a thin heat sink 85 is provided on the back surface side of the substrate 43.

FIG. 14 is a cross-sectional view of the power module 5 according to the fourth embodiment of the present invention. A thin heat sink 85 on the back surface side is arranged on the substrate 43. The lower housing 75 is provided with an opening 75a so as to dissipate heat to the outside from the thin heat sink 85 on the back surface side.

As a result, heat dissipation from the substrate 43 side can be further improved.

In the power module 5, a heat sink 80 and a thin heat sink 85 on the back surface side are provided on both sides of the power module 5, respectively.

As described above, the power module 5 further includes a housing 70 that houses the substrate 43, the power semiconductors 50 and 60, the conductive spacers 54 and 64, the conductive step absorbing portions 25 and 35, and the first heat spreaders 20 and 30. The housing 70 has a lower housing 75 arranged on the lower side of the substrate 43 and an upper housing 71 arranged on the upper side of the board 43.

The power module 5 further includes a back surface side thin heat sink 85 (heat sink) arranged on a surface opposite to the surface on which the power semiconductors 50 and 60 of the substrate 43 are mounted. The lower housing 75 has an opening 75a that exposes the thin heat sink 85 on the back surface side.

[Embodiment 5]
Embodiment 5 of the present invention will be described below with reference to FIG. For convenience of explanation, the same reference numerals are given to the members having the same functions as the members described in the above-described embodiment, and the description thereof will not be repeated. The fifth embodiment is characterized in that heat dissipation units are provided on both sides of the double-sided mounting board.

FIG. 15 is a cross-sectional view of the power module 6 according to the fifth embodiment of the present invention. The board 43B of the power module board 40B is a double-sided mounting board in which circuit patterns are mounted on both sides. On the back surface of the substrate 43B, a back surface side mounting component 93 and two back surface side spacers 95 are provided. The electrode 94 of the back surface side mounting component 93 is connected to a circuit pattern formed on the back surface side of the substrate 43B.

The back surface side conductive step absorbing portion 92 is provided so as to cover the back surface side mounting component 93 and the two back surface side spacers 95. The back surface side first heat spreader 91 is provided on the side opposite to the back surface side mounting component 93 of the back surface side conductive step absorbing portion 92. An insulating heat dissipation sheet 90 is provided on the side opposite to the back surface side conductive step absorbing portion 92 of the back surface side first heat spreader 91. Then, the back surface side heat sink 82 is provided on the side opposite to the back surface side first heat spreader 91 of the insulating heat dissipation sheet 90.

The back surface side heat sink 82 is fastened to the lower housing 75 by screws 79A. The heat sink 80 is fastened to the upper housing 71 with screws 79B.

In this way, heat sinks 80 and 82 are provided on both sides of the power module 6, respectively.

〔summary〕
The power modules 1, 2, 3, 4, 5, and 6 according to the first aspect of the present invention are arranged on the substrate 43 and the power semiconductors (Hi side or Lo side power semiconductors 50 and 60) arranged on the substrate 43. In order to dissipate heat generated from the conductive spacer (Hi side or Lo side conductive spacer 54, 64) and the power semiconductor (Hi side or Lo side power semiconductor 50, 60), the power semiconductor (Hi side) is used. Alternatively, a conductive step absorption portion (Hi side or Lo side conductivity) formed on the Lo side power semiconductors 50, 60) and the conductive spacer (Hi side or Lo side conductive spacers 54, 64) and having shrinkage. Heat generation of the power semiconductor (Hi side or Lo side power semiconductors 50, 60) via the step absorbing portion 25, 35) and the conductive step absorbing portion (Hi side or Lo side conductive step absorbing portion 25, 35). 1st heat spreader (Hi side or Lo side first heat spreader 20) provided on the conductive step absorbing portion (Hi side or Lo side conductive step absorbing portion 25, 35) in order to diffuse and dissipate heat. 30) and.

According to the above configuration, the heat generated by the power semiconductor is transferred from the power semiconductor to the first heat dissipation path through the substrate, the power semiconductor to the conductive step absorption portion, the conductive spacer, and the second heat dissipation path through the substrate, and the power semiconductor. The heat is dissipated through a plurality of heat dissipation paths of the third heat dissipation path passing through the conductive step absorbing portion and the first heat spreader. Then, the conductive step absorbing portion is deformed based on the pressing of the power semiconductor and the conductive spacer, so that the unintended step of the power semiconductor and the conductive spacer due to the variation in the thickness of the solder and the inclination at the time of mounting is absorbed. As a result, in a power module having a plurality of heat dissipation paths, it is possible to provide a power module having improved adhesion and contact between the power semiconductor and the heat dissipation member.

In the first aspect, the power modules 1, 2, 4, 5, and 6 according to the second aspect of the present invention have the conductive step absorbing portion (Hi side or Lo side conductive step absorbing portion 25, 35) and the power. Semiconductors (Hi-side or Lo-side power semiconductors 50, 60), the conductive spacers (Hi-side or Lo-side conductive spacers 54, 64), and the first heat spreader (Hi-side or Lo-side first heat spreaders 20, 30). A cushioning spacer (Hi) arranged on the substrate 43 so as to support the first heat spreader (Hi side or Lo side first heat spreader 20, 30) in order to reduce the respective contact thermal resistance between the two. It is preferable to further provide side or Lo side buffer spacers 58, 68).

According to the above configuration, the area where the parallelism between the first heat spreader and the substrate can be maintained is expanded, the contact property between the first heat spreader and the conductive step absorbing portion, and the heat dissipation surface of the conductive step absorbing portion and the power semiconductor. The contact thermal resistance can be reduced by improving the contactability between the two and the conductive step absorbing portion and the conductive spacer.

The power modules 1, 2, 3, 4, 5, and 6 according to the third aspect of the present invention include another power semiconductor (Lo side power semiconductor 60) arranged on the substrate 43 and the substrate in the first aspect. In order to dissipate heat generated from the other conductive spacer (Lo side conductive spacer 64) arranged on the 43 and the other power semiconductor (Lo side power semiconductor 60), the other power semiconductor (Lo side). The other conductive step absorbing portion (Lo side conductive step absorbing portion 35) formed on the power semiconductor 60) and the other conductive spacer (Lo side conductive spacer 64) and having shrinkage, and the other. In order to dissipate the heat generated by the other power semiconductor (Lo side power semiconductor 60) through the conductive step absorbing portion (Lo side conductive step absorbing portion 35) and dissipate heat, the other conductive step absorbing portion. Another first heat spreader (Lo side first heat spreader 30) provided on the (Lo side conductive step absorbing portion 35) so as to be insulated from the first heat spreader (Hi side first heat spreader 20), and the power semiconductor. The first heat spreader (Hi side first heat spreader 20) and the other first heat spreader in order to further diffuse and dissipate the heat generated by the (Hi side power semiconductor) and the other power semiconductor (Lo side power semiconductor 60). It is preferable to further include a second heat spreader 12 provided on the (Lo side first heat spreader 30).

According to the above configuration, since the other first heat spreader is provided so as to be insulated from the first heat spreader, the operation of the power module including the plurality of power semiconductors can be stabilized.

In the power modules 1, 2, 3, 4, 5, and 6 according to the fourth aspect of the present invention, in the third aspect, the power semiconductor is the Hi-side power semiconductor 50, and the other power semiconductor is the Lo-side power semiconductor 60. In the power semiconductor (Hi side power semiconductor 50), the conductive step absorbing portion (Hi side conductive step absorbing portion 25) and the conductive spacer are connected to the intermediate potential connection portion 56 provided on the substrate 43. (Hi side conductive spacer 54) is electrically connected, and the other power semiconductor (Lo side power semiconductor 60) is electrically connected to the ground potential connection portion 66 provided on the substrate 43. It is preferable that the step absorbing portion (Lo side conductive step absorbing portion 35) and the conductive spacer (Lo side conductive spacer 64) are electrically connected to each other.

According to the above configuration, since the potential of the surface opposite to the mounting surface of the plurality of power semiconductors is fixed, the operation of the power module including the plurality of power semiconductors can be stabilized.

In the first aspect, the power modules 1, 2, 3, 4, 5, and 6 according to the fifth aspect of the present invention include the substrate 43, the power semiconductor (Hi side or Lo side power semiconductors 50, 60), and the conductivity. The spacer (Hi side or Lo side conductive spacer 54, 64), the conductive step absorbing portion (Hi side or Lo side conductive step absorbing portion 25, 35), and the first heat spreader (Hi side or Lo side first). A housing 70 for accommodating the heat spreaders 20 and 30) is further provided, and the housing 70 is a lower housing 75 arranged on the lower side of the substrate 43 and an upper housing 71 arranged on the upper side of the board 43. The lower housing 75 and the upper housing 71 include the power semiconductor (Hi side or Lo side power semiconductors 50, 60) and the conductive spacer (Hi side or Lo side conductive spacer 54). It is preferable that 64) is joined so as to be pressed toward the conductive step absorbing portion (Hi side or Lo side conductive step absorbing portion 25, 35).

According to the above configuration, the conductive step absorbing portion is deformed by pressing to absorb unintended steps of the power semiconductor and the conductive spacer due to the variation in the thickness of the solder and the inclination at the time of mounting.

In the first aspect, the power module 3 according to the sixth aspect of the present invention includes the substrate 43, the power semiconductor (Hi side or Lo side power semiconductors 50, 60), and the conductive spacer (Hi side or Lo side conductive spacer). 54, 64)), the housing for accommodating the conductive step absorbing portion (Hi side or Lo side conductive step absorbing portion 25, 35), and the first heat spreader (Hi side or Lo side first heat spreader 20, 30). 70 is further provided, and the housing 70 has a lower housing 75 arranged on the lower side of the board 43 and an upper housing 71 arranged on the upper side of the board 43, and the upper housing 71. However, the conductive step absorbing portion (Hi side or Lo side conductive step absorbing portion 25, 35), the power semiconductor (Hi side or Lo side power semiconductor 50, 60), and the conductive spacer (Hi side or Lo). The first heat spreader (Hi side or It is preferable to have a protruding support portion (first heat spreader support portion 74) that projects in parallel with the substrate 43 so as to support the first heat spreader 20 and 30) on the Lo side.

According to the above configuration, by forming the protruding support portion in the housing, the area where the parallelism between the first heat spreader and the substrate can be maintained is expanded, and the contact property between the first heat spreader and the conductive step absorbing portion is expanded. The contact thermal resistance can be reduced by improving the contact between the conductive step absorption part and the heat dissipation surface of the power semiconductor and the contact between the conductive step absorption part and the conductive spacer. can.

In the first aspect, the power module 5 according to the seventh aspect of the present invention includes the substrate 43, the power semiconductor (Hi side or Lo side power semiconductors 50, 60), and the conductive spacer (Hi side or Lo side conductive spacer). 54, 64), a housing that accommodates the conductive step absorbing portion (Hi side or Lo side conductive step absorbing portion 25, 35), and the first heat spreader (Hi side or Lo side first heat spreader 20, 30). 70 is further provided, and the housing 70 has a lower housing 75 arranged on the lower side of the substrate 43 and an upper housing 71 arranged on the upper side of the board 43, and the power semiconductor (Hi). A heat sink (Hi side or Lo side power semiconductor 50, 60) arranged on a surface opposite to the power semiconductor (Hi side or Lo side power semiconductor 50, 60) of the substrate 43 in order to diffuse and dissipate heat generated by the side or Lo side power semiconductors 50, 60). It is preferable that the lower housing 75 further includes a back surface side thin heat sink 85) and has an opening 75a for exposing the heat sink (back surface side thin heat sink 85).

According to the above configuration, by arranging the heat sink on the surface of the substrate opposite to the power semiconductor, heat dissipation from the back surface of the substrate can be enhanced.

The method for manufacturing a power module according to the eighth aspect of the present invention includes a power semiconductor (Hi side or Lo side power semiconductors 50, 60) arranged on the substrate 43 and a conductive spacer (Hi) arranged on the substrate 43. To dissipate heat generated from the power module substrate forming step of forming the power module substrate 43 including the side or Lo side conductive spacers 54, 64) and the power semiconductor (Hi side or Lo side power semiconductors 50, 60). The conductive step absorbing section (Hi side or Lo side conductive step absorbing section 25, 35) provided in the above and the conductive step absorbing section (Hi side or Lo side conductive step absorbing section 25, 35). ), The heat dissipation unit forming step of forming the heat dissipation unit 10 including the first heat spreader (Hi side or Lo side first heat spreader 20, 30), the substrate 43, and the power semiconductor (Hi side or Lo). Side power semiconductors 50, 60), the conductive spacer (Hi side or Lo side conductive spacer 54, 64), the conductive step absorption section (Hi side or Lo side conductive step absorption section 25, 35), and the above. A lower housing 75 arranged below the substrate 43 of the housing 70 accommodating the first heat spreader (Hi-side or Lo-side first heat spreaders 20, 30) and an upper housing arranged above the substrate 43. 71 is a power semiconductor (Hi side or Lo side power semiconductor 50, 60) and the conductive spacer (Hi side or Lo side conductive spacer 54, 64) is the conductive step absorption portion (Hi side or Lo). It includes a housing joining step of joining so as to be pressed toward the side conductive step absorbing portions 25, 35).

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

1 Power module 10 Heat dissipation unit 12 2nd heat spreader 20 Hi side 1st heat spreader (1st heat spreader)
25 Hi side conductive step absorbing part (conductive step absorbing part)
30 Lo side 1st heat spreader (1st heat spreader)
35 Lo side conductive step absorbing part (conductive step absorbing part)
40 Power module board 43 Board 50 Hi side power semiconductor (power semiconductor)
54 Hi side conductive spacer (conductive spacer)
56 Intermediate potential connection 58 Hi side cushioning spacer (buffering spacer)
60 Lo side power semiconductor (power semiconductor)
64 Lo side conductive spacer (conductive spacer)
66 Ground potential connection 68 Lo side buffer spacer (buffer spacer)
70 Housing 71 Upper housing 74 1st heat spreader support part (protruding support part)
75 Lower housing 75a Opening 85 Back side thin heat sink (heat sink)
91 Back side first heat spreader 92 Back side conductive step absorber

Claims (8)

Power semiconductors placed on the substrate and
With the conductive spacer arranged on the substrate,
In order to dissipate heat generated from the power semiconductor, a conductive step absorbing portion formed on the power semiconductor and the conductive spacer and having shrinkage, and a conductive step absorbing portion.
A first heat spreader provided on the conductive step absorbing portion in order to diffuse heat generated by the power semiconductor and dissipate heat through the conductive step absorbing portion.
A power module characterized by being equipped with. In order to reduce the contact thermal resistance between the conductive step absorbing portion and the power semiconductor, the conductive spacer, and the first heat spreader, the first heat spreader is supported on the substrate. The power module according to claim 1, further comprising a spacer for cushioning to be arranged. With other power semiconductors arranged on the substrate,
With other conductive spacers placed on the substrate,
In order to dissipate heat generated from the other power semiconductor, the other power semiconductor and another conductive step absorbing portion formed on the other conductive spacer and having shrinkage.
In order to diffuse the heat generated by the other power semiconductor and dissipate heat through the other conductive step absorbing portion, the other conductive step absorbing portion is provided on the other conductive step absorbing portion so as to be insulated from the first heat spreader. 1st heat spreader and
An insulating heat dissipation sheet provided on the first heat spreader and the other first heat spreader in order to further diffuse and dissipate heat generated by the power semiconductor and the other power semiconductor.
A second heat spreader provided on the insulating heat dissipation sheet and
The power module according to claim 1. The power semiconductor is a Hi-side power semiconductor.
The other power semiconductor is a Lo-side power semiconductor.
The power semiconductor is electrically connected to an intermediate potential connection portion provided on the substrate via the conductive step absorbing portion and the conductive spacer.
The power module according to claim 3, wherein the other power semiconductor is electrically connected to a ground potential connection portion provided on the substrate with the conductive step absorbing portion via the conductive spacer. Further comprising a housing for accommodating the substrate, the power semiconductor, the conductive spacer, the conductive step absorbing portion, and the first heat spreader.
The lower housing in which the housing is arranged under the substrate and the lower housing
It has an upper housing arranged on the upper side of the substrate, and has an upper housing.
The power module according to claim 1, wherein the lower housing and the upper housing are joined so that the power semiconductor and the conductive spacer are pressed toward the conductive step absorbing portion. Further comprising a housing for accommodating the substrate, the power semiconductor, the conductive spacer, the conductive step absorbing portion, and the first heat spreader.
The lower housing in which the housing is arranged under the substrate and the lower housing
It has an upper housing arranged on the upper side of the substrate, and has an upper housing.
The upper housing supports the first heat spreader in order to reduce the contact thermal resistance between the conductive step absorbing portion and the power semiconductor, the conductive spacer, and the first heat spreader. The power module according to claim 1, wherein the power module has a protruding support portion that protrudes in parallel with the substrate. Further comprising a housing for accommodating the substrate, the power semiconductor, the conductive spacer, the conductive step absorbing portion, and the first heat spreader.
The lower housing in which the housing is arranged under the substrate and the lower housing
It has an upper housing arranged on the upper side of the substrate, and has an upper housing.
Further provided with a heat sink arranged on the surface of the substrate opposite to the power semiconductor in order to diffuse and dissipate heat generated by the power semiconductor.
The power module according to claim 1, wherein the lower housing has an opening for exposing the heat sink. A power module substrate forming step of forming a power module substrate including a power semiconductor arranged on the substrate and a conductive spacer arranged on the substrate.
A heat dissipation unit that forms a heat dissipation unit including a conductive step absorbing portion provided for radiating heat generated from the power semiconductor and having shrinkage, and a first heat spreader provided on the conductive step absorbing portion. The formation process and
The lower housing arranged below the substrate and the upper side of the substrate of the housing accommodating the substrate, the power semiconductor, the conductive spacer, the conductive step absorbing portion, and the first heat spreader. Manufacture of a power module comprising a housing joining step of joining the upper housing so that the power semiconductor and the conductive spacer are pressed toward the conductive step absorbing portion. Method.

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