WO2023022001A1

WO2023022001A1 - Power module and power conversion device

Info

Publication number: WO2023022001A1
Application number: PCT/JP2022/029905
Authority: WO
Inventors: 純司藤野; 智香川添; 周平高田; 裕児井本; 文雄和田
Original assignee: 三菱電機株式会社
Priority date: 2021-08-20
Filing date: 2022-08-04
Publication date: 2023-02-23
Also published as: CN117769761A; JPWO2023022001A1

Abstract

Provided is a technique for enabling reduction of thermal stress due to bonding of a heat-dissipating member and an insulating substrate, and suppression of warping of the heat-dissipating member caused by the thermal stress. A power module (202) comprises: a heat-dissipating member (14) including a peripheral wall portion (15) and a recess portion (19) formed on the inner peripheral side of the peripheral wall portion (15) and recessed downward; at least one ceramic substrate (10) bonded inside the recess portion (19); a plurality of semiconductor elements mounted on the at least one ceramic substrate (10); a case (5) fixed along the upper end of the peripheral wall portion (15) and internally filled with a sealing resin (7); and a circuit forming member including electrode plates (63, 64, 65) respectively connecting between the plurality of semiconductor elements and between the semiconductor elements and the at least one ceramic substrate (10). The thickness of the peripheral wall portion (15) of the heat-dissipating member (14) in the vertical direction (Z-axis direction) is greater than the thickness of a bottom wall portion (16), forming a bottom surface of the recess portion (19), in the vertical direction (Z-axis direction).

Description

Power modules and power converters

The present disclosure relates to power modules and power converters.

Power modules are installed in all kinds of products, from industrial equipment to home appliances and information terminals, and are becoming more and more popular in all aspects of electrical energy generation, transmission, and regeneration as environmental problems grow. Among them, power modules mounted on electric vehicles are required to have high heat radiation performance and high flatness in order to secure fastening to water cooling jackets.

In addition, power modules are also required to have a package form that can be applied to SiC semiconductors, which are likely to become mainstream in the future due to their high operating temperature and excellent efficiency.

For example, Patent Document 1 discloses a power module provided with a metal base (corresponding to a heat dissipation member) having heat dissipation fins.

WO2013/141154

Since power modules handle large currents and high voltages, ceramic substrates with high insulation and heat dissipation performance are used as insulating substrates. Its coefficient of linear expansion is remarkably smaller than that of copper and aluminum, which are used as materials for components. Therefore, when the heat radiating member and the insulating substrate are joined together, a large thermal stress is generated at the joint, and there is a problem that the heat radiating member is likely to warp and crack during temperature cycles.

In the technique described in Patent Document 1, V-grooves are formed in a metal base on which a plurality of ceramic substrates are mounted, and the structure is such that the heat generated by the semiconductor elements on the respective ceramic substrates does not interfere. Therefore, the effect of reducing the thermal stress can be expected by reducing the rigidity of the metal base.

Therefore, an object of the present disclosure is to provide a technique capable of reducing thermal stress due to bonding between a heat dissipating member and an insulating substrate and suppressing warping of the heat dissipating member caused by the thermal stress.

A power module according to the present disclosure includes: a heat dissipation member having a peripheral wall portion; a concave portion formed on the inner peripheral side of the peripheral wall portion and recessed downward; at least one insulating substrate bonded to the concave portion; a plurality of semiconductor elements mounted on one of the insulating substrates; a case fixed along the upper end of the peripheral wall portion and filled with a sealing material; and a circuit forming member including electrode plates respectively connecting between and at least one of the insulating substrates, wherein the thickness in the vertical direction of the peripheral wall portion of the heat radiating member is equal to that of the bottom wall portion forming the bottom surface of the recess. Thicker than vertical thickness.

According to the present disclosure, the vertical thickness of the bottom wall portion forming the bottom surface of the recess to which the insulating substrate is joined in the heat radiating member is thinner than the vertical thickness of the peripheral wall portion. Thermal stress due to bonding can be reduced. On the other hand, since the vertical thickness of the peripheral wall portion of the heat radiating member is greater than the vertical thickness of the bottom wall portion, the rigidity of the heat radiating member can be ensured. Therefore, it is possible to suppress the warping of the heat dissipating member caused by the thermal stress due to the bonding between the heat dissipating member and the insulating substrate.

The objects, features, aspects, and advantages of this disclosure will become more apparent with the following detailed description and accompanying drawings.

1 is a cross-sectional view of a power module (6 in 1) according to Embodiment 1; FIG. 1 is a top view of a power module (6 in 1) according to Embodiment 1. FIG. FIG. 4 is a schematic diagram showing a manufacturing process of the power module (6 in 1) according to Embodiment 1; FIG. 8 is a schematic diagram showing another example of the manufacturing process of the power module (6 in 1) according to Embodiment 1; FIG. 10A is a top view of a power module (6 in 1) according to Modification 1 of Embodiment 1, and a cross-sectional view of a partition. FIG. 8 is a cross-sectional view of a power module (6 in 1) according to Modification 2 of Embodiment 1; FIG. 10 is a top view of a power module (6 in 1) according to Modification 2 of Embodiment 1; FIG. 8 is a cross-sectional view of a power module (6 in 1) according to Embodiment 2; FIG. 10 is a top view of a power module (6 in 1) according to Embodiment 2; FIG. 11 is a cross-sectional view of a power module (6 in 1) according to a modification of Embodiment 2; FIG. 11 is a top view of a power module (6 in 1) according to Embodiment 3; FIG. 11 is a block diagram showing the configuration of a power conversion system to which a power conversion device according to Embodiment 4 is applied;

<Embodiment 1>
<Configuration>
Embodiment 1 will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a power module 202 (6in1) according to Embodiment 1. FIG. FIG. 2 is a top view of the power module 202 (6in1) according to the first embodiment. It should be noted that the sealing resin 7 is omitted in FIG. 2 in order to make the drawing easier to see.

In FIG. 1, the X direction, Y direction and Z direction are orthogonal to each other. The X, Y and Z directions shown in the following figures are also orthogonal to each other. Hereinafter, the direction including the X direction and the −X direction, which is the direction opposite to the X direction, is also referred to as the “X-axis direction”. Also, hereinafter, the direction including the Y direction and the −Y direction, which is the direction opposite to the Y direction, is also referred to as the “Y-axis direction”. Also, hereinafter, a direction including the Z direction and the −Z direction, which is the direction opposite to the Z direction, is also referred to as the “Z-axis direction”.

As shown in FIGS. 1 and 2, the power module 202 includes a heat dissipation member 14, two ceramic substrates 10, six IGBTs (Insulated Gate Bipolar Transistors) 21, six diodes 22, a case 5, and a signal A terminal 61 , an external terminal 62 , an electrode plate 63 , an N-side electrode plate 64 and a P-side electrode plate 65 are provided. Here, the ceramic substrate 10 corresponds to an insulating substrate, and the IGBTs 21 and diodes 22 correspond to semiconductor elements.

The heat radiating member 14 is made of an aluminum alloy and includes a peripheral wall portion 15 , a bottom wall portion 16 , a partition portion 17 , a plurality of cooling pins 18 and recesses 19 .

The bottom wall portion 16 is formed in a rectangular shape when viewed from the Z direction. The peripheral wall portion 15 is formed in a rectangular frame shape when viewed from the Z direction, and surrounds the outer peripheral side of the bottom wall portion 16 . The peripheral wall 15 has a length of 90 mm in the front-rear direction (Y-axis direction), a length of 70 mm in the left-right direction (X-axis direction), and a thickness of 4 mm in the vertical direction (Z-axis direction).

The recessed portion 19 is formed on the inner peripheral side of the peripheral wall portion 15 and is formed in a shape recessed downward (-Z direction). Specifically, the recessed portion 19 is formed by the inner peripheral surface of the peripheral wall portion 15 and the upper surface (Z-direction surface) of the bottom wall portion 16 .

The partition part 17 extends in the front-rear direction (Y-axis direction) and is provided in the center of the recess 19 in the left-right direction (X-axis direction). The partition portion 17 is formed integrally with the bottom wall portion 16 from an aluminum alloy. The partition portion 17 has a uniform thickness in the vertical direction (Z-axis direction). A gap is formed between the partition portion 17 and the electrode plate 63 so that the upper end (end in the Z direction) of the partition portion 17 does not contact the electrode plate 63 positioned above the partition portion 17 .

The recessed portion 19 is divided into two in the left-right direction (X-axis direction) by the partition portion 17 . The left side portion (−X direction portion) of the concave portion 19 has a length of 61 mm in the front-rear direction (Y-axis direction), a length of 31 mm in the left-right direction (X-axis direction), and a depth in the vertical direction (Z-axis direction). is 3 mm. On the other hand, the right side portion (the portion in the X direction) of the concave portion 19 has a length of 61 mm in the front-rear direction (Y-axis direction), a length of 34 mm in the left-right direction (X-axis direction), and a depth of 34 mm in the vertical direction (Z-axis direction). The height is 3 mm.

A P-side electrode plate 65 is arranged on the left side of the recess 19 (part in the -X direction), and an N-side electrode plate 64 is arranged on the right side of the recess 19 (the part in the X direction). Hereinafter, the left portion (part in the -X direction) of the recess 19 will be referred to as the P side, and the right portion (part in the X direction) of the recess 19 will be referred to as the N side.

The thickness of the partition portion 17 in the vertical direction (Z-axis direction) is 4 mm, which is the same as the thickness of the peripheral wall portion 15 in the vertical direction (Z-axis direction). Note that the partitioning portion 17 is not an essential component, and the partitioning portion 17 can be eliminated when it is not necessary to divide the concave portion 19 into two. In this case, only one ceramic substrate 10 may be arranged. It is also possible to provide two or more partitions 17 to divide the recess 19 into three or more.

　180 cooling pins 18 protruding downward (−Z direction) are arranged on the lower surface (−Z direction surface) of the bottom wall portion 16 . The cooling pin 18 has a diameter of 2 mm and a vertical (Z-axis) length of 5 mm.

The entire surface of the heat dissipation member 14 is plated with nickel. The upper surface (surface in the Z direction) of the bottom wall portion 16 is divided into two by a partition portion 17, and two ceramic substrates 10 are joined to each of these two divided portions using solder 30. there is

Each ceramic substrate 10 includes a base material 11 made of aluminum nitride, a back conductor layer 12 made of copper, and a surface conductor layer 13 made of copper. A back conductor layer 12 is formed by brazing on the back surface (surface in the −Z direction) of the base material 11, and a surface conductor layer 13 is formed on the surface (surface in the Z direction) of the base material 11 by brazing. It is formed by forming a film by attaching.

The base material 11 arranged on the P side has a length in the front-rear direction (Y-axis direction) of 60 mm, a length in the left-right direction (X-axis direction) of 30 mm, and a thickness in the vertical direction (Z-axis direction) of 0.64 mm. is. The base material 11 arranged on the N side has a length in the front-rear direction (Y-axis direction) of 60 mm, a length in the left-right direction (X-axis direction) of 33 mm, and a thickness in the vertical direction (Z-axis direction) of 0.64 mm. is.

The back conductor layer 12 disposed on the P side has a length of 56 mm in the front-rear direction (Y-axis direction), a length of 26 mm in the left-right direction (X-axis direction), and a thickness of 0.2 mm in the vertical direction (Z-axis direction). 8 mm. The back conductor layer 12 disposed on the N side has a length of 56 mm in the front-rear direction (Y-axis direction), a length of 29 mm in the left-right direction (X-axis direction), and a thickness of 0.2 mm in the vertical direction (Z-axis direction). 8 mm.

The surface conductor layer 13 disposed on the P side has a length of 56 mm in the front-rear direction (Y-axis direction), a length of 26 mm in the left-right direction (X-axis direction), and a thickness of 0.2 mm in the vertical direction (Z-axis direction). 8 mm. On the N side, three surface conductor layers 13 are formed side by side in the Y-axis direction. The surface conductor layer 13 disposed on the N side has a length of 17 mm in the front-rear direction (Y-axis direction), a length of 29 mm in the left-right direction (X-axis direction), and a thickness of 0.2 mm in the vertical direction (Z-axis direction). 8 mm.

Three sets of IGBTs 21 and diodes 22 are mounted via solder 30 on the upper surface (the surface in the Z direction) of the surface conductor layer 13 arranged on the P side. The content of solder 30 is 96.5% tin, 3% silver and 0.5% copper, and the melting point of solder 30 is 217°C.

The IGBT 21 is made of silicon, and has a length of 15 mm in the front-rear direction (Y-axis direction), a length of 15 mm in the left-right direction (X-axis direction), and a thickness of 0.2 mm in the vertical direction (Z-axis direction). be.

The diode 22 is made of silicon, and has a length of 15 mm in the front-rear direction (Y-axis direction), a length of 10 mm in the left-right direction (X-axis direction), and a thickness of 0.5 mm in the vertical direction (Z-axis direction). 2 mm.

The surface electrodes (not shown) of the three pairs of IGBTs 21 and diodes 22 are respectively joined to three electrode plates 63 made of copper using solder 30 . The thickness of the electrode plate 63 in the vertical direction (Z-axis direction) is 0.5 mm.

The case 5 is made of PPS (Poly Phenylene Sulfide: heat resistant temperature 280° C.) resin and is formed in a rectangular frame shape when viewed from the Z direction. not shown). The case 5 has a length in the front-rear direction (Y-axis direction) of 90 mm, a length in the left-right direction (X-axis direction) of 70 mm, and a thickness in the vertical direction (Z-axis direction) of 6 mm.

Three external terminals 62 made of copper are insert-molded in the portion corresponding to the P side of the case 5, and furthermore, a P-side electrode plate 65 made of copper is also insert-molded together with the external terminals. The three external terminals 62 correspond to the U-, V-, and W-phase circuits, respectively. The three electrode plates 63 are arranged to straddle the adjacent ceramic substrates 10, and one ends of the three electrode plates 63 are joined to the three external terminals 62 using solder 30, respectively.

The other ends of the three electrode plates 63 intersect the partition 17 and extend toward the ceramic substrate 10 arranged on the N side. Specifically, the other end portions of the three electrode plates 63 pass above the partition portion 17 (in the Z direction) and are attached to the three surface conductor layers 13 arranged on the N side using solder 30. are spliced. The thickness of the external terminal 62 and the P-side electrode plate 65 in the vertical direction (Z-axis direction) is 0.5 mm.

The P-side common drain is joined to a copper P-side electrode plate 65 using solder (not shown). The thickness of the P-side electrode plate 65 in the vertical direction (Z-axis direction) is 0.5 mm.

On the other hand, IGBTs 21 and diodes 22 are mounted one by one via solder 30 on the upper surfaces (surfaces in the Z direction) of the three surface conductor layers 13 arranged on the N side.

An N-side electrode plate 64 made of copper is inserted together with the external terminal into the portion of the case 5 corresponding to the N-side. Surface electrodes (not shown) of the three sets of IGBTs 21 and diodes 22 are joined to the N-side electrode plate 64 using solder 30 . The thickness of the N-side electrode plate 64 in the vertical direction (Z-axis direction) is 0.5 mm.

In addition, six signal terminals 61 made of copper are insert-molded together with external electrodes in portions corresponding to the P side and the N side of the case 5 . A signal electrode 211 of the IGBT 21 is joined to a signal terminal 61 by a wire 41 made of aluminum. The thickness of the signal terminal 61 in the vertical direction (Z-axis direction) is 0.5 mm, and the diameter of the wire 41 is 0.15 mm.

Here, the electrode plate 63, the N-side electrode plate 64, and the P-side electrode plate 65 correspond to circuit forming members that connect between a plurality of semiconductor elements and between the semiconductor elements and the ceramic substrate 10, respectively. Also, the IGBT 21 and the diode 22 are connected on the P side and the N side so as to form a U-, V-, and W-phase circuit.

The concave portion 19 of the heat radiating member 14 and the inside of the case 5 are insulated and sealed by being filled with the sealing resin 7 . The sealing resin 7 is epoxy resin in which silica filler is dispersed. Here, the sealing resin 7 corresponds to a sealing material.

<Manufacturing process>
Next, the manufacturing process of the power module 202 will be described with reference to FIGS. 3(a) to 3(d). 3A to 3D are schematic diagrams showing manufacturing steps of the power module 202 (6 in 1) according to the first embodiment.

As shown in FIG. 3A, a sheet-shaped solder 30 having a thickness of 0.3 mm in the vertical direction (Z-axis direction) and a ceramic substrate are applied to the upper surface (Z-direction surface) of the bottom wall portion 16 of the heat dissipation member 14 . 10 is placed, and a sheet-like solder 30 having a thickness of 0.2 mm in the vertical direction (Z-axis direction), an IBGT 21 and a diode 22 are placed on the surface conductor layer 13 of the ceramic substrate 10 (Z direction), and further A sheet of solder 30 having a thickness of 0.2 mm in the vertical direction (Z-axis direction) is positioned and placed on each surface electrode (not shown) (Z direction).

By heating this assembly up to 260° C. in a reflow furnace to melt the solder 30, solder joints are performed as shown in FIG. 3(b).

Next, as shown in FIG. 3(c), the case 5 in which the signal terminals 61 and the external terminals 62 are inserted is adhered to the heat dissipation member 14 using an adhesive (not shown). After positioning and arranging the electrode plate 63, this assembly is heated to 260° C. in a reflow furnace to melt the solder 30 on the IBGT 21 and the diode 22 for joining. At this time, since the material of the case 5 is PPS and its heat resistance temperature is 280.degree. C., the case 5 has heat resistance against the maximum temperature of 260.degree. The solder 30 contains 95% tin and 5% antimony and has a melting point of 240°C. 220.degree.

Next, as shown in FIG. 3(d), the wire 41 is used to join the signal electrode 211 (see FIG. 2) of the IGBT 21 to the signal terminal 61. Next, as shown in FIG. After that, a liquid sealing resin 7 is injected into the inside of the case 5 and cured by heating in an oven at 150° C. for 1 hour to complete the sealing. Thereby, the power module 202 is completed.

Alternatively, instead of the method of FIGS. 3(a) to (d), it is also possible to manufacture the power module 202 by the method of FIGS. 4(a) to (c). 4A to 4C are schematic diagrams showing another example of the manufacturing process of the power module 202 (6in1) according to the first embodiment.

As shown in FIG. 4A, a sheet-shaped solder 30 having a thickness of 0.3 mm in the vertical direction (Z-axis direction) and a ceramic substrate are applied to the upper surface (Z-direction surface) of the bottom wall portion 16 of the heat dissipation member 14 . 10 is arranged, and on the surface conductor layer 13 of the ceramic substrate 10 (Z direction), a sheet-like solder 30 having a thickness of 0.2 mm in the vertical direction (Z-axis direction), an IBGT 21 and a diode 22 are arranged. A sheet-like solder 30 having a thickness of 0.2 mm in the vertical direction (Z-axis direction) is positioned and placed on the surface electrodes (not shown) of (Z-direction). Furthermore, the electrode plate 63 and the N-side electrode plate 64 are positioned and mounted thereon (in the Z direction).

By heating this assembly to 260° C. in a reflow furnace to melt the solder 30, solder joints are performed as shown in FIG. 4(b).

Next, as shown in FIG. 4(c), the case 5 in which the signal terminals 61 and the external terminals 62 are inserted is adhered to the heat dissipation member 14 using an adhesive (not shown). The electrode plate 63 and the external terminal 62 are bonded using the conductive adhesive 31 (curing conditions: 180° C., 1 h).

The wire 41 is used to join the signal electrode 211 (see FIG. 2) of the IGBT 21 and the signal terminal 61 . After that, a liquid sealing resin 7 is injected into the inside of the case 5 and cured by heating in an oven at 150° C. for 1 hour to complete the sealing. Thereby, the power module 202 is completed.

By mounting and soldering the electrode plate 63 and the N-side electrode plate 64 before attaching the case 5 to the assembly, the assembly can be placed in the reflow furnace only once. Also, by bonding the electrode plate 63 and the external terminal 62 using the conductive adhesive 31, it is possible to use a case material with a low heat resistance. Here, the conductive adhesive 31 is used for bonding the electrode plate 63 and the external terminal 62, but low temperature solder such as Bi—Sn (melting point 139° C.) may be used, or normal temperature solder such as TIG welding or ultrasonic bonding may be used. It is also possible to use a bonding process.

<effect>
As described above, the power module 202 according to the first embodiment includes the heat dissipation member 14 having the peripheral wall portion 15 and the concave portion 19 formed on the inner peripheral side of the peripheral wall portion 15 and recessed downward. a plurality of semiconductor elements mounted on the at least one ceramic substrate 10; and a circuit forming member including

electrode plates

63, 64, and 65 connecting between a plurality of semiconductor elements and between the semiconductor elements and at least one ceramic substrate 10, respectively, and the peripheral wall portion 15 of the heat dissipation member 14 The thickness in the vertical direction (Z-axis direction) is greater than the thickness in the vertical direction (Z-axis direction) of the bottom wall portion 16 that forms the bottom surface of the recess 19 .

Therefore, the thickness in the vertical direction (Z-axis direction) of the bottom wall portion 16 forming the bottom surface of the concave portion 19 to which the ceramic substrate 10 is joined in the heat dissipation member 14 is greater than the thickness in the vertical direction (Z-axis direction) of the peripheral wall portion 15. Since the ceramic substrate 10 is also thin, the thermal stress due to bonding between the heat radiating member 14 and the ceramic substrate 10 can be reduced. On the other hand, since the thickness of the peripheral wall portion 15 of the heat radiating member 14 in the vertical direction (Z-axis direction) is greater than the thickness of the bottom wall portion 16 in the vertical direction (Z-axis direction), the rigidity of the heat radiating member 14 can be ensured. can. Therefore, it is possible to suppress warpage of the heat dissipation member 14 caused by thermal stress due to bonding between the heat dissipation member 14 and the ceramic substrate 10 .

As described above, by suppressing the warpage of the heat dissipation member 14, the power module 202 can be used for a long period of time, leading to a reduction in energy consumption and a reduction in the environmental load of the production process.

In addition, since at least one ceramic substrate 10 and the heat dissipation member 14 are joined with solder 30 having a melting point lower than the heat-resistant temperature of the case 5, deformation of the case 5 due to heat during soldering can be suppressed.

In addition, since the electrode plate 63 and the external terminal 62 formed on the case 5 are joined by the conductive adhesive 31 whose heating temperature is lower than that of the solder 30, a material with a low heat resistance temperature is used as the material of the case 5. becomes possible.

At least one ceramic substrate 10 includes a plurality of ceramic substrates 10, and the heat dissipation member 14 is provided with a partition portion 17 which is arranged between adjacent ceramic substrates 10 and which divides the concave portion 19 into a plurality of portions. .

Therefore, by providing the partition portion 17 in the concave portion 19, the rigidity of the bottom wall portion 16 of the heat radiating member 14 can be improved, so that warping of the heat radiating member 14 can be further suppressed.

<Modification of Embodiment 1>
Next, a modification of Embodiment 1 will be described. 5A is a top view of power module 202 (6 in 1) according to Modification 1 of Embodiment 1, and FIG.

As shown in FIG. 5( a ), the power module 202 has a partition portion 171 instead of the partition portion 17 . The partition portion 171 has a different shape at the upper end (end in the Z direction) from the partition portion 17 .

While the thickness in the vertical direction (Z-axis direction) of the partition portion 17 was uniform, the thickness in the vertical direction (Z-axis direction) of the portion of the partition portion 171 intersecting the electrode plate 63 was different from that of the other portions. It is formed thinner than the thickness in the vertical direction (Z-axis direction) of the portion. Specifically, the upper end (the end in the Z direction) of the partition portion 171 that intersects with the electrode plate 63 is at a higher position (the position in the Z-axis direction) than the upper end (the end in the Z direction) of the other portions. ) is formed low.

Here, the portion of the partition 171 that intersects with the electrode plate 63 is the portion 171b excluding both ends 171a in the extending direction of the partition 171, and the other portion is the extending direction of the partition 171. is both ends 171a.

In Modification 1 of Embodiment 1, the circuit forming member is arranged to straddle the adjacent ceramic substrates 10, and the thickness in the vertical direction (Z direction) of the portion of partition 171 that intersects the circuit forming member is is thinner than the thickness in the vertical direction (Z direction) of other portions.

Therefore, while ensuring a sufficient insulation distance between the partition 171 and the electrode plate 63, the thickness of the partition 171 in the vertical direction (Z direction) is minimized to only the necessary parts, thereby dissipating heat. The rigidity of the member 14 can be ensured.

FIG. 6 is a cross-sectional view of a power module 202 (6in1) according to Modification 2 of Embodiment 1. FIG. FIG. 7 is a top view of a power module 202 (6in1) according to Modification 2 of Embodiment 1. FIG. It should be noted that the sealing resin 7 is omitted in FIG. 7 in order to make the drawing easier to see.

In Embodiment 1, the electrode plate 63, the N-side electrode plate 64, and the P-side electrode plate 65 are used as the circuit forming members. A wire 42 may be used. The wire 42 has a diameter of 0.4 mm.

In this case, instead of the N-side electrode plate 64 and the P-side electrode plate 65, an N-side terminal 64a and a P-side terminal 65a are provided. Further, on the surface conductor layer 13 of the ceramic substrate 10 arranged on the N side, a conductor layer 131 is formed to collect the wires 42 connected to the surface electrodes of the IGBT 21 and the diode 22, and the conductor layer 131 and the N side terminal 64a are formed. are connected using wires 42 . Also, the surface conductor layer 13 of the ceramic substrate 10 arranged on the P side and the P side terminal 65a are connected using a wire 42 .

When the wire 42 is used to form a circuit, even if the shape or dimensions of the mounted IGBT 21 and diode 22 are changed, it can be handled by changing the program of the wire bonder. Also, when the circuit is formed using the wire 42, the stress at the junction is lower than when the circuit is formed using the electrode plate 63, the N-side electrode plate 64, and the P-side electrode plate 65. It is also possible to seal the circuit forming member with a flexible silicone gel as the resin 7 .

<Embodiment 2>
Next, a power module 202 according to Embodiment 2 will be described. FIG. 8 is a cross-sectional view of power module 202 (6 in 1) according to the second embodiment. FIG. 9 is a top view of power module 202 (6 in 1) according to the second embodiment. In FIG. 9, the sealing resin 7 is omitted in order to make the drawing easier to see. In the second embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

As shown in FIGS. 8 and 9, in the second embodiment, the power module 202 includes a partition portion 51 instead of the partition portion 17, and the partition portion 51 is formed integrally with the case 5. . Specifically, the partition portion 51 connects the central portions in the left-right direction (X-axis direction) of the front wall (the wall in the −Y direction) and the rear wall (the wall in the Y direction) inside the case 5 . formed.

As in the case of Modification 1 of Embodiment 1, in order to ensure both the insulation distance between partition 51 and electrode plate 63 and the rigidity of partition 51, partition 51 includes: The upper end (Z-direction end) of the portion intersecting the electrode plate 63 is formed at a lower height position (Z-axis direction position) than the upper end (Z-direction end) of the other portion. The upper ends (Z-direction ends) of both ends of the partition portion 51 in the extending direction have the same height position (Z-axis direction position) as the upper end (Z-direction ends) of the case 5 .

Also, the three electrode plates 63 are integrated with the three external terminals 62 respectively, and are formed by inserting into the case 5 . By bonding the case 5 to the heat dissipation member 14 with an adhesive (not shown), the partition portion 51 is bonded to the bottom surface of the recess 19 .

As described above, in the power module 202 according to the second embodiment, since the partition portion 51 is formed integrally with the case 5, a part of the case 5 functions as a partition for the concave portion 19 of the heat dissipation member 14, By bonding the case 5 to the heat radiating member 14 with an adhesive (not shown), the rigidity of the heat radiating member 14 can be secured by a part of the case 5 .

<Modification of Embodiment 2>
FIG. 10 is a cross-sectional view of a power module 202 (6in1) according to a modification of the second embodiment. As shown in FIG. 10 , a partition 51 integrally formed with the case 5 may be combined with the partition 17 integrally formed with the heat radiating member 14 . Specifically, the partitions 51 are formed in portions corresponding to both ends in the extending direction of the partitions 51 shown in FIGS. It is formed in a portion corresponding to a portion of the portion 51 excluding both ends in the extending direction. By bonding the case 5 to the heat dissipation member 14 with an adhesive (not shown), the

partitions

51 and 17 are bonded together. Also in this case, the same effects as in the case of the second embodiment can be obtained.

<Embodiment 3>
Next, a power module 202 according to Embodiment 3 will be described. FIG. 11 is a top view of a power module (6in1) according to Embodiment 3. FIG. In FIG. 11, the sealing resin 7 is omitted in order to make the drawing easier to see. In addition, in Embodiment 3, the same components as those described in Embodiments 1 and 2 are denoted by the same reference numerals, and descriptions thereof are omitted.

In Embodiments 1 and 2, one ceramic substrate 10 is arranged on the N side, and three surface conductor layers 13 constituting the ceramic substrate 10 are formed. Furthermore, in Embodiment 3, the ceramic substrate 10 arranged on the N side is divided into three parts corresponding to the U, V, and W phase circuits, respectively. Specifically, three ceramic substrates 10 are arranged side by side in the Y-axis direction on the N side.

The U-, V-, and W-phase circuits are arranged on one ceramic substrate 10 on the P side, which shares the surface conductor layer 13 as the drain. On the other hand, on the N side where the surface conductor layer 13 is to be insulated, the U-, V-, and W-phase circuits are arranged on three ceramic substrates 10, respectively.

As described above, in the power module 202 according to the third embodiment, the circuit forming member includes the N-side electrode plate 64, the IGBTs 21 and the diodes 22 are connected so as to form a U-, V-, and W-phase circuit, and a plurality of Among the ceramic substrates 10, the ceramic substrate 10 on which the IGBTs 21 and the diodes 22 connected to the N-side electrode plate 64 are mounted is divided into three so as to correspond to the U-, V-, and W-phase circuits respectively.

As the size of the ceramic substrate 10 increases, the thermal stress generated in the ceramic substrate 10 and the heat dissipation member 14 also increases. Since the dimensions in the X-axis direction and the Y-axis direction of the ceramic substrate 10 are smaller than those in the first and second embodiments, the thermal stress generated in the ceramic substrate 10 and the heat dissipation member 14 can be reduced. This makes it possible to suppress the warp of the heat radiating member 14 more than in the first and second embodiments.

<Modifications of Embodiments 1 to 3>
In the above description, aluminum nitride was used as the material for the base material 11 of the ceramic substrate 10, but the same effects as those described above can be obtained by using silicon nitride or alumina.

In the above description, the back conductor layer 12 and the front conductor layer 13 are made of copper. By asking the question, the same effect as the above case can be obtained.

In the above description, an aluminum alloy is used as the material of the heat dissipation member 14, but the same effect as the above case can be obtained even if copper or a copper alloy is used.

In the above description, the IGBT 21 and the diode 22 are made of silicon, but the same effect can be obtained by using wide bandgap semiconductors such as silicon carbide and gallium nitride.

In the above description, solder 30 containing 96.5% tin, 3% silver, and 0.5% copper and having a melting point of 217° C. was used. % with a melting point of 224° C., or with a tin content of 95% and antimony of 5% and a melting point of 240° C., the same effect as the above case can be obtained. Also, the same effects as those described above can be obtained by partially replacing the solder with a bonding material such as a silver epoxy adhesive, a silver sintered material, or a brazing material.

Although the wires 41 made of aluminum are used as the wires 41 in the above, the same effect as the above can be obtained by using wires made of an aluminum alloy or copper containing a small amount of an additive such as iron.

In the above, the case 5 made of PPS was used, but it is also possible to improve the heat resistance by replacing it with one made of LCP (Liquid Crystal Polymer).

In the above, various electrode plates made of copper were used, but the same effect as the above case can be obtained even if they are appropriately nickel-plated or replaced with those made of copper alloy or nickel-plated aluminum.

In the above description, an epoxy resin in which silica filler is dispersed is used as the sealing resin 7. However, a filler such as alumina may be used, or an epoxy resin mixed with a silicone resin may be used to achieve the same effect as in the above case. is obtained. Also, the same effect as the above case can be obtained by a method of sealing only with a silicone resin.

In addition, in the partition portion 17, it is desirable that the thickness in the vertical direction (Z-axis direction) at least at both ends in the extending direction is the same as the thickness in the vertical direction (Z-axis direction) of the peripheral wall portion 15, but is slightly thicker. This alone has the effect of increasing the rigidity. Also, if the solder 30 used for joining has a thickness of 0.3 mm or more in the vertical direction (Z-axis direction), the outflow of the solder 30 can be suppressed.

If the sum of the thickness of the back conductor layer 12 in the vertical direction (Z-axis direction) and the thickness of the substrate 11 in the vertical direction (Z-axis direction) is less than 1.1 mm, the ceramic substrate 10 can be positioned. By overlapping the back conductor layer 12 and the base material 11 while functioning, it is possible to suppress warping without increasing the size of the power module 202 .

In addition, if ceramic substrates 10 with different specifications or different dimensions may be arranged and it is difficult to form the partitions 17 in the heat dissipation member 14, in the soldering process of FIG. It is also possible to join while suppressing warpage by heating or cooling while fixing the heat radiating member 14 by attaching a pressing jig to the portion where the heat radiating member 14 is to be bent. Even when the heat radiating member 14 is formed with the partition portion 17, a pressing jig for suppressing warping is considered effective.

In addition, the wire 42 may be used as a circuit forming member as in the second modification of the first embodiment for the second embodiment, the modification of the second embodiment, and the third embodiment. Further, when connecting the electrode plate 63 and the external terminal 62 in Modification 1 of Embodiment 1, Embodiment 2, and Embodiment 3, a conductive adhesive 31 is used as shown in FIG. good too.

Further, with respect to the third embodiment, instead of the partitioning section 17 as in the first modification of the first embodiment, a partitioning section 171 may be provided, or the partitioning section 17 may be provided as in the second embodiment. Alternatively, a partition portion 51 may be provided. Furthermore, the partitioning portion 51 may be combined with the partitioning portion 17 as in the modification of the second embodiment in contrast to the third embodiment.

<Embodiment 4>
The present embodiment applies the power modules according to the first to third embodiments described above to a power converter. Although application of the power modules according to Embodiments 1 to 3 is not limited to a specific power converter, the power modules according to Embodiments 1 to 3 are applied to a three-phase inverter as Embodiment 4. is applied.

FIG. 12 is a block diagram showing the configuration of a power conversion system to which the power converter according to Embodiment 4 is applied.

The power conversion system shown in FIG. 12 is composed of a power supply 100, a power converter 200, and a load 300. The power supply 100 is a DC power supply and supplies DC power to the power converter 200 . The power supply 100 can be composed of various things, for example, it can be composed of a DC system, a solar battery, a storage battery, or it can be composed of a rectifier circuit or an AC/DC converter connected to an AC system. good too. Also, the power supply 100 may be configured by a DC/DC converter that converts DC power output from the DC system into predetermined power.

The power conversion device 200 is a three-phase inverter connected between the power supply 100 and the load 300 , converts the DC power supplied from the power supply 100 into AC power, and supplies the AC power to the load 300 . As shown in FIG. 12, the power conversion device 200 includes a main conversion circuit 201 that converts DC power into AC power and outputs it, and a control circuit 203 that outputs a control signal for controlling the main conversion circuit 201 to the main conversion circuit 201. and

The load 300 is a three-phase electric motor driven by AC power supplied from the power converter 200 . Note that the load 300 is not limited to a specific application, but is an electric motor mounted on various electrical equipment, such as a hybrid vehicle, an electric vehicle, a railway vehicle, an elevator, or an electric motor for air conditioning equipment.

The details of the power converter 200 will be described below. The main conversion circuit 201 includes a switching element (not shown) and a freewheeling diode (not shown). By switching the switching element, the DC power supplied from the power supply 100 is converted into AC power, and the load is 300 supplies. Although there are various specific circuit configurations of the main conversion circuit 201, the main conversion circuit 201 according to the present embodiment is a two-level three-phase full bridge circuit, and has six switching elements and It can consist of six freewheeling diodes in anti-parallel. Each switching element and each freewheeling diode of the main conversion circuit 201 is configured by a power module 202 corresponding to any one of the first to third embodiments described above. Six switching elements are connected in series every two switching elements to form upper and lower arms, and each upper and lower arm forms each phase (U phase, V phase, W phase) of the full bridge circuit. Output terminals of the upper and lower arms, that is, three output terminals of the main conversion circuit 201 are connected to the load 300 .

Further, the main conversion circuit 201 includes a drive circuit (not shown) for driving each switching element, but the drive circuit may be built in the power module 202 or may may be provided. The drive circuit generates a drive signal for driving the switching element of the main conversion circuit 201 and supplies it to the control electrode of the switching element of the main conversion circuit 201 . Specifically, in accordance with a control signal from the control circuit 203, which will be described later, a drive signal for turning on the switching element and a drive signal for turning off the switching element are output to the control electrode of each switching element. When maintaining the switching element in the ON state, the driving signal is a voltage signal (ON signal) equal to or higher than the threshold voltage of the switching element, and when maintaining the switching element in the OFF state, the driving signal is a voltage equal to or less than the threshold voltage of the switching element. signal (off signal).

The control circuit 203 controls the switching elements of the main conversion circuit 201 so that the desired power is supplied to the load 300 . Specifically, based on the power to be supplied to the load 300, the time (on time) during which each switching element of the main conversion circuit 201 should be in the ON state is calculated. For example, the main conversion circuit 201 can be controlled by PWM control that modulates the ON time of the switching element according to the voltage to be output. Then, a control command (control signal) to the drive circuit provided in the main conversion circuit 201 so that an ON signal is output to the switching element that should be in the ON state at each time point, and an OFF signal is output to the switching element that should be in the OFF state. to output The drive circuit outputs an ON signal or an OFF signal as a drive signal to the control electrode of each switching element according to this control signal.

In the power conversion device 200 according to the present embodiment, the power module 202 according to Embodiments 1 to 3 is applied as the switching element and freewheeling diode of the main conversion circuit 201, so durability can be improved.

In the present embodiment, an example in which the power modules 202 according to Embodiments 1 to 3 are applied to a two-level three-phase inverter has been described. It is not limited and can be applied to various power converters. In this embodiment, a two-level power conversion device is used, but a three-level or multi-level power conversion device may be used. The power modules 202 according to 1 to 3 may be applied. Further, when power is supplied to a DC load or the like, it is possible to apply the power module 202 according to Embodiments 1 to 3 to a DC/DC converter or an AC/DC converter.

Further, the power conversion device to which the power module 202 according to Embodiments 1 to 3 is applied is not limited to the case where the above-described load is an electric motor. It can also be used as a power supply device for a device or a contactless power supply system, and can also be used as a power conditioner for a photovoltaic power generation system, an electric storage system, or the like.

Although this disclosure has been described in detail, the above description is, in all aspects, illustrative and not restrictive. It is understood that innumerable variations not illustrated can be envisaged.

It should be noted that each embodiment can be freely combined, modified, or omitted as appropriate.

5 case, 7 sealing resin, 10 ceramic substrate, 14 heat dissipation member, 15 peripheral wall, 16 bottom wall, 17 partition, 19 recess, 21 IGBT, 22 diode, 30 solder, 31 conductive adhesive, 42 wire, 51 Divider, 62 External terminal, 63 Electrode plate, 64 N-side electrode plate, 65 P-side electrode plate, 171 Divider, 200 Power converter, 201 Main conversion circuit, 202 Power module, 203 Control circuit.

Claims

a heat dissipating member having a peripheral wall portion and a concave portion formed on the inner peripheral side of the peripheral wall portion and recessed downward;
at least one insulating substrate bonded within the recess;
a plurality of semiconductor elements mounted on at least one insulating substrate;
a case fixed along the upper end of the peripheral wall portion and filled with a sealing material;
a circuit forming member including an electrode plate that connects between a plurality of the semiconductor elements and between the semiconductor elements and the at least one insulating substrate, respectively;
In the power module, the thickness of the peripheral wall portion of the heat radiating member in the vertical direction is greater than the thickness of the bottom wall portion forming the bottom surface of the recess in the vertical direction.
The power module according to claim 1, wherein at least one of said insulating substrates and said heat radiating member are joined by solder having a lower melting point than the heat-resistant temperature of said case.
The power module according to claim 2, wherein the electrode plate and the external terminals formed on the case are joined with a joining material having a heating temperature lower than that of the solder.
at least one said insulating substrate comprises a plurality of said insulating substrates;
4. The power module according to any one of claims 1 to 3, wherein the heat dissipation member is provided with a partition portion that is arranged between the adjacent insulating substrates and divides the concave portion into a plurality of portions.
The circuit forming member is arranged to straddle the adjacent insulating substrates,
5. The power module according to claim 4, wherein the vertical thickness of a portion of the partition portion intersecting with the circuit forming member is smaller than the vertical thickness of the other portions.
The power module according to claim 4 or 5, wherein the partition part is formed integrally with the case.
The circuit forming member includes an N-side electrode plate,
the plurality of semiconductor elements are connected to form a U-, V-, and W-phase circuit;
3. Among the plurality of insulating substrates, the insulating substrate on which the semiconductor element connected to the N-side electrode plate is mounted is divided into three so as to correspond to the U-, V-, and W-phase circuits, respectively. The power module according to any one of claims 4 to 6.
a main conversion circuit having the power module according to any one of claims 1 to 7, for converting input power and outputting the power;
a control circuit that outputs a control signal for controlling the main conversion circuit to the main conversion circuit;
A power conversion device comprising: