JP2009164156A - Power module - Google Patents

Abstract

Provided is a power module that has excellent heat dissipation performance when a semiconductor element generates heat, and that hardly causes cracks in a sealing resin body as a potting material.
A power module includes a first cooler and a housing that is mounted on one side surface of the first cooler and includes a plurality of partition walls intersecting in a lattice shape to form a plurality of receiving spaces. 2, a circuit unit 7 composed of an insulating substrate 71 and a semiconductor element 72 accommodated in the accommodation space 10, and a sealing unit filled and cured between the circuit unit 7, the partition wall, and the first cooler 1. It is formed from the resin body 3 and the second cooler 4 provided on the opposite side of the circuit unit 7 from the first cooler 1 side.
[Selection] Figure 1

Description

  The present invention relates to a housing type power module that exhibits a structure for cooling a semiconductor element from both sides and is excellent in heat dissipation performance and crack durability performance.

  In a power module equipped with a semiconductor element such as an IGBT (Insulated Gate Bipolar Transistor), the heat generated from the element is efficiently radiated, and adjustment is made so that the temperature is lower than the reference temperature even when the heat is generated.

  Here, in the power module, a semiconductor element is soldered to one side surface of an insulating substrate made of a laminate of an aluminum nitride (AlN) plate or a pure aluminum plate, and heat from the semiconductor element is insulated to the other side surface of the insulating substrate. A cooler for radiating heat is connected by soldering or an adhesive. In addition to the plate-shaped heat sink, this cooler has various forms such as those provided with a function of circulating a coolant such as cold water, and those combined with each other. More specifically, these are accommodated in a housing made of a resin material such as plastic and potted with a sealing resin to form a power module.

  Here, conventional power modules include a single-sided cooling housing type in which a cooler is provided only on one side of a semiconductor element, and a so-called power card type in which a cooler is provided on both sides of the semiconductor element to cool both sides. In the housing type, all semiconductor elements are arranged in a flat cooler, the periphery thereof is surrounded by a housing in which electric wiring such as a bus bar is in-molded, and the inside is potted with a gel-like resin. On the other hand, in the power module type, one semiconductor element, a tube for cooling both sides of the semiconductor element, and a lead frame for electrical connection with another unit are integrated with a sealing resin body, and one circuit unit and To do.

  By the way, a single-sided cooling housing type power module is difficult to cool on both sides due to its structure, and therefore, heat dissipation is inferior to that of a power card type. The reason is that the height dimensional accuracy of each semiconductor element deteriorates due to the warp of the cooler, and a gap is often formed between the separate cooler provided on the upper side of each semiconductor element. The effect is not expected despite the double-sided cooling structure. Therefore, when potting with a high thermal conductive resin material instead of a gel-like resin body to try to prevent the formation of gaps, this time, due to the size of the surface size of this resin material, shrinkage during molding and The expansion and contraction caused by the cooling and heating cycle causes cracks and breakage of the bonding wires.

  On the other hand, the power card type is superior in heat dissipation compared to the single-sided housing type, but on the other hand, there are problems that the number of components is relatively increased, the connection process is increased, and the assemblability is poor. The reason for this is that each power card is equipped with a lead frame for electrical connection between the power cards, external electrical wiring such as a bus bar is required outside of the power card, and cooling connection between the power cards Another reason is that a separate cooling tube is provided outside and it is necessary to fasten it with the power card. Therefore, it is possible to arrange the cooling tubes on both sides of the power card without in-molding the cooling tubes in the power card, but in this case, it is necessary to apply heat radiation grease between the power card and the cooling tube. This work will greatly deteriorate the assemblability.

  Patent Document 1 can be cited as a technique related to a conventional power module. In this power module, a metal substrate for cooling is provided on the upper and lower surfaces of the semiconductor element, and a resin is potted between the bases, but in this power module, due to the warp of the metal substrate in the cooling and heating cycle, The subject that the possibility that a crack will generate | occur | produce in a sealing resin body is high is considered.

JP 2006-13080 A

  The present invention has been made in view of the above-described problems, and has an object to provide a power module that has excellent heat dissipation performance when a semiconductor element generates heat and is less likely to crack in a sealing resin body that is a potting material. To do.

  To achieve the above object, a power module according to the present invention includes a first cooler, a housing mounted on one side of the first cooler, and a plurality of partition walls intersect to form a plurality of receiving spaces. A circuit unit composed of an insulating substrate and a semiconductor element housed in the housing space, a sealing resin body filled and cured in the housing space, and a side of the circuit unit opposite to the first cooler side. And a second cooler provided in the.

  In the power module of the present invention, first, in order to enhance the heat dissipation of the heat generated in the circuit unit, the circuit unit is molded with a high heat dissipation resin, and the first cooling that spreads the plurality of circuit units in a plane. Even if the cooler is warped due to resin molding shrinkage or cooling cycle during molding, the mold resin cracks or mold resin shrinkage due to this warping or resin molding shrinkage It is a power module that can effectively prevent the breaking of the bonding wire and has excellent heat dissipation.

  As a basic configuration, a housing unit mounted on one side of the cooler is configured such that a plurality of partition walls intersect to form a housing space, and a circuit unit including an insulating substrate and a semiconductor element is provided in each housing space. While accommodating, a sealing resin body is formed in this accommodation space. As described above, the cooler may be in any form such as a plate-shaped heat sink, a device that circulates cold water, cold air, or the like.

  As a result of the sealing resin body being divided by, for example, grid-like partition walls, it is suppressed from spreading in a plane. As a result, even if the entire power module is out of plane due to heat, each divided sealing resin The body is less likely to crack.

  Here, as a resin to be used, a resin such as an epoxy resin, a urethane resin, a silicone resin, an acrylic resin, or an olefin resin can be used. In order to further improve the heat dissipation, silica, alumina, boron nitride It is preferable to mix fillers such as silicon nitride, silicon carbide, and magnesium oxide in a predetermined content ratio.

  The power module according to the present invention includes a separate cooler (second cooler) above the first cooler below the first cooler as a measure for further improving the heat dissipation. is there. Specifically, a second cooler that is in direct or indirect contact with the upper surface of the circuit unit (this cooler also recirculates a plate-shaped heat sink, cold water, cold air, etc., like the first cooler). For example, the second cooler is formed integrally with the power module by embedding a part of the second cooler in the sealing resin body.

  Here, regarding the form in which the second cooler indirectly contacts the upper surface of the circuit unit, there is a form in which a heat dissipation material is interposed between the circuit unit and the second cooler. This heat dissipating material may be soldered to the second cooler in advance, or may be soldered to the upper surface of the circuit unit. The heat dissipating material can be composed of a face material that is in contact with the second cooler and a leg portion that supports the face material. The leg portion is connected to the circuit unit and the height of the leg portion is increased. By adjusting, it becomes possible to effectively transfer the heat from the circuit unit to the second cooler. This heat dissipating material is also preferably formed from the same heat conducting material metal as the first and second coolers.

  Moreover, regarding the second cooler, as a measure for further increasing the connection strength with the sealing resin body, there is a form in which the second cooler includes a flange on its side and the flange is embedded in the sealing resin body. .

  Further, with respect to the housing, a concave groove is formed on the end surface of the partition opposite to the side in contact with the first cooler, for example, a concave groove corresponding to the end surface of the plurality of partition walls is formed. There is also a form in which a plate-like second cooler common to the plurality of concave grooves is fitted.

  For example, in the case where eight storage spaces of 2 columns × 4 rows are formed by lattice-shaped partition walls, a common plate-like second cooler is provided above each of the four storage spaces in each column. In the case of providing, by accommodating a plate-like second cooler, a groove is formed at the end of each partition wall so as to accommodate the plate-like second cooler, The heat radiation performance from above the power module can be enhanced with as few coolers as possible.

  Further, in the form of fitting the plate-like second cooler described above, in order to fill the housing space with resin after the second cooler is fitted into the concave groove, It is preferable to form an unoccluded region that is not partially obstructed by the second cooler, and fill the storage space with resin through the unoccluded region. Here, as a form of the non-blocking region, a second cooler having an area smaller than the area formed by the grid-like partition walls is provided, or a through-hole is drilled in the second cooler. There is a form such as leaving.

  According to the power module of the present invention described above, heat is dissipated with high heat transfer from the vertical direction by the coolers provided above and below and the sealing resin body of the high heat transfer material filled and cured in the accommodation space. Therefore, the heat radiation performance can be remarkably enhanced as compared with the conventional power module. Furthermore, by dividing the sealing resin body into as small an area (small volume) as possible by the grid-shaped partition walls, it is possible to effectively generate cracks in the sealing resin body even when the power module expands and contracts due to heat. Therefore, the crack durability can be increased.

  This power module is suitable for an inverter mounted on a hybrid vehicle or an electric vehicle, etc., whose production has been recently expanded and heat dissipation and durability against high heat generation such as a drive source are urgent issues. .

  As can be understood from the above description, according to the power module of the present invention, it is possible to provide a power module excellent in both heat dissipation performance and crack durability.

  Embodiments of the present invention will be described below with reference to the drawings. 1 is a plan view of the power module of the present invention, FIG. 2 is a view taken along the line II-II in FIG. 1, FIG. 3 is a view taken along the line III-III in FIG. 1, and FIG. It is an IV-IV arrow line view. The radix of the accommodation space defined by the grid-shaped partition walls is not limited to the illustrated embodiment, and the second cooler mounted above the power module is not limited to the illustrated embodiment. The form etc. which provided the resin filling part in the position corresponding to each accommodation space may be sufficient while closing the accommodation space.

  In the illustrated power module 100, a housing 2 is mounted above a flat plate-shaped first cooler 1, and the housing 2 is defined by a lattice-shaped partition wall to form a plurality of housing spaces 10. ing. As shown in FIG. 3, each of the accommodation spaces 10 accommodates a circuit unit 7 in which a semiconductor element 72 is mounted on an insulating substrate 71. Specifically, the insulating substrate 71 is a first cooling member. For example, two circuit units 7 and 7 are connected to each other by a thin metal wire 82 in one housing space 10, and lead terminals projecting on the power module laterally in the housing space 10 81 is further connected.

  The two circuit units 7 and 7 housed in one housing space 10 are soldered with the leg portions of the heat radiation material 6 having a gate shape when viewed from the front. A second cooler 4 is provided at intervals.

  Although not shown, a flow path through which a coolant such as cold water, cold air, or cold oil flows is formed in the first and second coolers 1 and 4, and the coolant provided from a coolant source (not shown) Is provided to the second cooler 4 through the connecting pipe 5 connecting the first and second coolers 1 and 4 after providing the cold energy below the power module 100 through the first cooler 1. The cooling power is provided above the power module 100, and the heat radiation performance from the vertical direction of the power module 100 is enhanced by the action of the refrigerant.

  In the embodiment shown in the figure, seven storage spaces 10 are formed in each row in two rows of grid-like partition walls, and a common second cooler 4 is provided across the seven storage spaces 10 for each row. It has been.

  Here, as shown in FIG. 4, a concave groove 21 into which the second cooler 4 is fitted is formed in each lattice wall, and the second cooler 4 is bonded within the concave groove 21. By being fixed, it is integrally fixed above the power module 100.

  In FIG. 1, resin is filled into the accommodation space 10 through a gap formed between the accommodation space 10 and the second cooler 4. Although not shown, the second cooler 4 completely covers the accommodation space 10 in a planar manner, and through holes are formed at positions corresponding to the accommodation spaces 10 of the cooler 4. The form which fills each accommodation space 10 with resin through a through-hole may be sufficient.

  In the housing space 10, a resin and filler mixed material is filled and cured to form a sealing resin body 3, and the sealing resin body 3 not only seals the circuit unit 7 but also from the circuit unit 7. The heat radiation effect to the first and second coolers 1 and 2 is enhanced.

  Here, as the resin forming this mixed material, any one of epoxy resin, urethane resin, silicone resin, acrylic resin, olefin resin and the like can be used, and as filler, silica, alumina, boron nitride Any one filler can be used from silicon nitride, silicon carbide, magnesium oxide, and the like. Further, by adjusting the filler content in the mixed material to about 60 to 70 vol%, a highly thermally conductive sealing resin body 3 having a thermal conductivity of 1 to 5 W / mK can be formed, and a lattice-like partition wall The crack durability can be further enhanced in combination with the small area (small volume).

  Furthermore, by forming from a mixed material having a filler content in the above range, a highly tough sealing resin body having a thermal expansion coefficient of about 15 to 30 ppm can be formed.

  In addition, regarding the groove 21 shown in FIG. 4, there is a gap between the groove 21 and the second cooler 4 in a normal temperature atmosphere, and the cooling due to a difference in thermal expansion due to preheating when the sealing resin is filled. It is preferable to set the dimensions so that there is no gap between the container 4 and the container 4.

  FIG. 5 is a view taken along the line III-III in FIG. 1 like FIG. 3, and is a diagram for explaining another embodiment of the second cooler.

  The second cooler 4A is provided with a flange 41 projecting outwardly below the second cooler 4A. The flange 41 is embedded in the sealing resin body 3, thereby the second cooler 4A and the sealing resin body. The bond strength of 3 can be increased. The flange 41 is provided only at a position corresponding to the accommodation space 10 in the second cooler 4A, and is not provided at a portion corresponding to the concave groove 21 at the end of the lattice-like partition wall.

  According to the power module 100 described above, the sealing resin body is divided into small areas (small volumes) by the lattice-shaped partition walls formed in the housing, thereby improving the crack durability of the sealing resin body. be able to. Furthermore, the coolers 1 and 4 are arranged in the vertical direction of the power module 100. Furthermore, a sealing resin body made of a resin (and a mixed material of fillers) of a high heat dissipation material is disposed in the plurality of housing spaces 10. By being formed, the heat dissipation performance of the power module 100 is remarkably enhanced. This power module with high durability and excellent heat dissipation is most suitable for application to recent hybrid vehicles and electric vehicles that require high performance, high durability, and high heat dissipation in the mounted devices.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

It is a top view of the power module of the present invention. It is an II-II arrow line view of FIG. It is the III-III arrow line view of FIG. It is the IV-IV arrow line view of FIG. It is the III-III arrow line view of FIG. 1, Comprising: It is the figure explaining other embodiment of the 2nd cooler.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... 1st cooler, 2 ... Housing (partition wall), 3 ... Sealing resin body, 4 and 4A ... 2nd cooler, 41 ... Flange, 5 ... Connection pipe, 6 ... Radiation material, 7 ... Circuit unit , 71 ... Insulating substrate, 72 ... Semiconductor element, 81 ... Lead terminal, 82 ... Metal fine wire, 10 ... Housing space, 100 ... Power module

Claims (6)

A first cooler;
A housing mounted on one side of the first cooler, wherein a plurality of partition walls intersect to form a plurality of accommodating spaces;
A circuit unit comprising an insulating substrate and a semiconductor element housed in the housing space;
A sealing resin body filled and cured in the housing space;
The power module which consists of a 2nd cooler provided in the opposite side to the 1st cooler side among the said circuit units.   The power module according to claim 1, wherein a heat dissipation material is interposed between the circuit unit and the second cooler.   The power module according to claim 1 or 2, wherein the second cooler includes a flange on a side thereof, and the flange is embedded in the sealing resin body. A concave groove is formed on the end face of the partition opposite to the side in contact with the first cooler,
The said recessed groove corresponding to the said end surface of the said some partition is formed, The plate-shaped 2nd cooler common to several this recessed groove is fitted, The any one of Claims 1-3 The power module described in 1.   A part of the accommodating space is an unoccluded region that is not obstructed by the second cooler, and the unoccluded region is a gap region between the lattice-shaped partition wall and the second cooler, or The power module according to any one of claims 1 to 4, wherein the power module is any one of a through-hole drilled in the second cooler.   The power module according to claim 1, wherein the sealing resin body is made of a highly heat conductive resin material or a mixed material of a resin and a filler.

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