JP2020088010A - Cooler, base plate thereof, and semiconductor device - Google Patents

Abstract

To provide a cooler capable of avoiding adverse effects on a member to be cooled due to thermal expansion and contraction of a base plate.SOLUTION: A cooler according to the present invention includes a box-shaped container body 1 having an opening on the upper surface, and a base plate 5 on which a member to be cooled can be arranged on the upper surface side of an inner peripheral portion 6, and the lower surface side of the outer peripheral portion 7 of the base plate 5 is fixed to the peripheral edge portion of the upper surface opening of the container body 1, and therefore, the base plate 5 is intended for a cooler assembled so as to close the upper surface opening 11 of the container body 1. The inner peripheral portion 6 of the base plate 5 is formed separately from the outer peripheral portion 7 via a gap S, and the inner peripheral portion 6 and the outer peripheral portion 7 are connected to each other a low buffer portion 8 having a strength higher than that of the inner peripheral portion 6 and the outer peripheral portion 7.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cooler used for cooling power semiconductor elements and the like and a base plate thereof, and further to a semiconductor device including the cooler.

BACKGROUND ART Power semiconductor elements used to control main power of electric motors such as hybrid vehicles (HVs) and electric vehicles (EVs), industrial machinery, home appliances, power driving equipment such as information terminals are large in handling large power. With fever. For this reason, in order to avoid the adverse effects of high heat and maintain high performance, a cooler is bonded or adhered to the mounting board on which the power semiconductor element is mounted, and the heat generated by the cooler is released. I have to.

If a large space for heat dissipation can be secured around the mounting board, such as in stationary equipment, an air-cooled cooler can be used, but many in a limited space such as an automobile. In the case where the above devices are densely arranged, it is usual to employ a liquid-cooled (water-cooled) cooler.

The following Patent Documents 1 and 2 disclose liquid cooling type coolers for cooling the mounting substrate. This cooler includes a box-shaped container body such as a water cooling jacket having an opening on the upper surface, and a base plate attached so as to close the upper surface opening of the container body. A large number of heat radiation fins are integrally formed on the lower surface side of the inner peripheral portion of the base plate, and a mounting board is mounted on the upper surface side. The outer peripheral portion of the base plate is fixed to the peripheral edge portion of the upper surface opening of the container body in a state where the large number of heat radiation fins of the base plate are accommodated in the container main body through the upper surface opening. With this, the container body and the base plate form a refrigerant flow path through which a refrigerant such as cooling water flows, and the refrigerant supplied from the outside of the cooler to one end of the refrigerant flow path passes through the refrigerant flow path to the outside from the other end. Configured to be spilled into. In this way, the coolant circulated in the coolant passage of the cooler and the semiconductor element exchange heat with each other through the base plate and the heat radiation fins, and the heat generated from the semiconductor element is released to the outside through the coolant. The semiconductor element is cooled by this.

A mounting substrate used for such a semiconductor device includes an insulating plate such as a ceramic plate, a wiring layer such as solder laminated on both upper and lower surfaces of the insulating plate, and a semiconductor element laminated on the upper wiring layer. Each of these layer members is laminated and integrated via a brazing material or the like. The lower wiring layer of the mounting board is laminated and integrated with the base plate of the cooler via a brazing material.

JP, 2016-92209, A JP, 2008-67691, A

In the conventional coolers disclosed in Patent Documents 1 and 2, there is a concern that the thermal expansion and contraction of the base plate may adversely affect the mounting board and the like. For example, during operation of the cooler, the base plate and the mounting substrate are cooled, and the base plate and the mounting substrate are thermally contracted toward the inner side (inner diameter direction). On the other hand, the base plate is made of aluminum or copper (including alloys thereof; the same applies hereinafter), and the insulating plate of the mounting board is made of ceramic or the like, so the thermal expansion coefficients of the two are greatly different. .. Therefore, the contraction rate of the base plate during thermal contraction becomes larger than that of the insulating plate, and the insulating plate cannot follow the contracting operation of the base plate, and the mounting board including the insulating plate bends due to the stress during the contraction, A so-called mountain warp occurs in which the central portion of the mounting board rises upward. When the mounting substrate warps in this manner, the semiconductor element or the insulating plate may have a poor contact with the wiring layer, which may cause a malfunction, or the heat dissipation performance may be deteriorated. Not only that, but in some cases, the insulating plate is cracked and damaged, and the insulating performance is also impaired.

The present invention has been made in view of the above problems, and provides a cooler capable of avoiding an adverse effect on a member to be cooled such as a mounting substrate due to thermal expansion and contraction of the base plate, the base plate, and a semiconductor device. The purpose is to

In order to solve the above-mentioned subject, the present invention comprises the following means.

[1] A box-shaped container body having an opening on the upper surface, and a base plate on which an object to be cooled can be arranged on the upper surface side of the inner peripheral portion, and the lower surface side of the outer peripheral portion of the base plate is the upper surface opening of the container body. A cooler in which the base plate is attached to the container body so as to close an upper surface opening thereof by being fixed to a peripheral portion,
The inner peripheral portion of the base plate is formed separately from the outer peripheral portion via a gap, and the inner peripheral portion and the outer peripheral portion have a lower strength than the inner peripheral portion and the outer peripheral portion. A cooler characterized in that it is connected via a section.

[2] The cooler according to the above item 1, wherein a bent portion having a V-shaped cross section is formed in the buffer portion.

[3] The cooler according to the above 1 or 2, wherein the outer peripheral portion of the base plate is formed of a material having high strength with respect to the inner peripheral portion.

[4] The cooler according to any one of the aforementioned Items 1 to 3, wherein the inner peripheral portion of the base plate is made of a material having a higher thermal conductivity than the outer peripheral portion.

[5] The cooler according to any one of items 1 to 3, wherein the outer peripheral portion and the inner peripheral portion of the base plate are made of aluminum.

[6] A base plate of a cooler, which is assembled to a box-shaped container body having an opening on the upper surface so as to close the upper opening,
An inner peripheral portion on which the cooling target member can be arranged on the upper surface side,
An outer peripheral portion that is provided outside the inner peripheral portion and that can be fixed to the upper surface opening edge portion of the container body on the lower surface side,
The inner peripheral portion is formed separately from the outer peripheral portion via a gap, and the inner peripheral portion and the outer peripheral portion are interposed via a buffer portion having lower strength than the inner peripheral portion and the outer peripheral portion. A base plate of a cooler characterized by being connected.

[7] A box-shaped container main body having an opening on the upper surface, a base plate whose lower surface side of an outer peripheral portion is fixed to a peripheral edge portion of the upper surface opening of the container main body to close the upper surface opening of the container main body, and the base plate A semiconductor device which is disposed on the upper surface side of the inner peripheral part of and which includes a mounting substrate including a semiconductor element,
The inner peripheral portion of the base plate is formed separately from the outer peripheral portion via a gap, and the inner peripheral portion and the outer peripheral portion have a lower strength than the inner peripheral portion and the outer peripheral portion. A semiconductor device, characterized in that the semiconductor devices are connected via parts.

[8] The semiconductor device according to the above item 7, wherein the mounting substrate includes an insulating plate, and the semiconductor element is arranged above the insulating plate.

According to the cooler of the invention [1], the inner peripheral portion of the base plate is formed separately from the outer peripheral portion with a gap therebetween, and the two are connected by the buffer portion having low strength. Even if the outer peripheral portion of the base plate undergoes thermal contraction during cooling to generate an inward stress on the outer peripheral portion, the stress is absorbed by the deformation of the buffer portion. Therefore, it is possible to surely avoid the adverse effect due to the thermal expansion and contraction of the base plate.

According to the cooler of the invention [2], when the buffer portion is deformed by the stress generated by thermal contraction or the like, the V-shaped bent portion serves as the deformation starting point and the deformation is started. Even if is small, the stress can be reliably absorbed, and the adverse effect of thermal expansion and contraction of the base plate can be more surely avoided.

According to the cooler of the invention [3], since the outer peripheral portion of the base plate is formed of a material having higher strength than the inner peripheral portion, the elastic repulsive force of the seal member interposed between the outer peripheral portion and the container body is prevented. However, the outer peripheral portion is not deformed. Therefore, the base plate can be securely attached to the container body with the seal member sufficiently compressed.

According to the cooler of the invention [4], since the inner peripheral portion of the base is formed of a material having high thermal conductivity, the cooling target member provided in the inner peripheral portion and the refrigerant in the container body are efficiently provided. Heat can be exchanged, and sufficient cooling performance can be reliably obtained.

According to the cooler of the invention [5], the above effects can be obtained more reliably.

According to the base plate of the cooler of the invention [6], since it has the same main part as described above, the same effect as described above can be obtained.

According to the semiconductor device of the invention [7], since the same main part as described above is provided, the same effect as the above can be obtained.

According to the semiconductor device of the invention [8], it is possible to reliably prevent the insulating plate from cracking due to thermal contraction.

FIG. 1 is a sectional view showing a power semiconductor device to which a cooler according to a first embodiment of the present invention is applied. FIG. 2 is a sectional view showing a power semiconductor device to which a cooler according to a second embodiment of the present invention is applied. 3A and 3B are enlarged cross-sectional views showing the periphery of the buffer portion in the semiconductor device of the second embodiment. FIG. 3A is a cross-sectional view in a normal state, and FIG. It is a sectional view in the state where it is. FIG. 4 is a sectional view showing a conventional power semiconductor device as a reference example.

<First Embodiment>
FIG. 1 is a sectional view showing a power semiconductor device to which a cooler according to a first embodiment of the present invention is applied. As shown in the figure, this semiconductor device includes a container body 1 such as a cooling jacket, a base plate 5, and a mounting substrate 2 as basic components.

In the present specification and claims, the term aluminum is used to include not only pure aluminum but also aluminum alloys, unless otherwise specified. Further, in the present specification and claims, terms such as “upper (upper)” and “lower (lower)” indicating directions are not based on the direction of gravity, but are shown in FIG. 1 for convenience. It is based on the state. That is, the cooler and the semiconductor device of the present invention are in actual use, in addition to the state shown in FIG. 1, for example, a state in which the top and bottom are inverted with respect to the state in FIG. Alternatively, it may be used in a state where the upper and lower parts are arranged obliquely.

In the semiconductor device of the first embodiment, the container body 1 is formed in a rectangular shape in plan view, and is formed in a box shape as a whole. The container body 1 has an opening 11 on the upper surface, and the inside of the container body 1 is opened upward by the upper surface opening 11.

The outer peripheral shape of the base plate 5 is formed in a rectangular shape corresponding to the outer peripheral shape of the container body 1 in a plan view. The base plate 5 constitutes a rectangular inner peripheral portion 6 forming an inner region of the base plate 5 and an outer peripheral region of the base plate 5, and is arranged outside the inner peripheral portion 6 with a gap S therebetween. A rectangular ring-shaped outer peripheral portion 7 and a rectangular ring-shaped cushioning portion 8 arranged in the gap S between the inner peripheral portion 6 and the outer peripheral portion 7 so as to close the gap S.

The inner peripheral portion 6 has an outer peripheral recessed step portion 65 formed above the outer peripheral edge portion. Further, the outer peripheral portion 7 has an inner peripheral concave stepped portion 75 formed above the inner peripheral edge portion. The inner portion of the buffer portion 8 is joined and integrated in a liquid-tight state by being placed on the outer peripheral concave step portion 65 of the inner peripheral portion 6, and the outer portion of the buffer portion 8 is located inside the outer peripheral portion 7. As it is placed on the circumferential concave step portion 75, it is joined and integrated in a liquid-tight state. As a result, the inner peripheral portion 6 and the outer peripheral portion 7 that are separately formed via the gap S are connected and integrated via the buffer portion 8 to form the base plate 5. The buffer portion 8 of the base plate 5 is arranged so as to fill the gap S between the inner peripheral portion 6 and the outer peripheral portion 7 over the entire circumference thereof.

In the first embodiment, the bonding (joining) method between the inner peripheral portion 6 and the buffer portion 8 and the bonding (bonding) method between the outer peripheral portion 7 and the buffer portion 8 are not particularly limited, and brazing Each of them is appropriately joined and integrated by an appropriate method such as a treatment, a welding treatment, and a knotting material coating treatment.

A large number of heat radiation fins 61 are integrally formed on the lower surface of the inner peripheral portion 6 so as to project downward. In the present embodiment, the structure of the radiation fin 61 is not particularly limited, and may be a plate fin or a pin fin. Further, when the pin fin is adopted, the cross-sectional shape is not limited, and it may be formed in any cross-sectional shape such as a circular shape, an elliptical shape, an oval shape, a polygonal shape, and an irregular shape.

In the first embodiment, the inner peripheral portion 6 of the base plate 5 is made of a material having a higher thermal conductivity than the outer peripheral portion 7. Further, the outer peripheral portion 7 is made of a material having higher strength than the inner peripheral portion 6.

Specifically, as the material of the inner peripheral portion 6, it is preferable to use pure aluminum having an alloy number of A1050 (thermal conductivity 230 W/mK, proof stress 30 MPa), A1100 (thermal conductivity 220 W/mK, proof stress 35 MPa). it can. As the material of the outer peripheral portion 7, an Al-Mg-Si alloy such as alloy No. A6063 (thermal conductivity 210 W/mK, proof stress 145 MPa), Al-Mg-Si alloy such as A3003 (thermal conductivity 170 W/mK, proof stress 125 MPa). A Mn-based alloy can be preferably used.

Further, in the present embodiment, the buffer portion 8 of the base plate 5 is made of a material having lower strength than the inner peripheral portion 6 and the outer peripheral portion 7. Specifically, as the material of the buffer portion 8, pure aluminum having an alloy number of A1050 (thermal conductivity of 230 W/mK, proof stress of 30 MPa), A1100 (thermal conductivity of 220 W/mK, proof stress of 35 MPa) or the like can be preferably used. ..

The base plate 5 having the above structure is assembled to the container body 1 to form a cooler. That is, the heat radiation fins 61 of the base plate 5 are accommodated in the container body 1 through the upper surface opening 11 of the container body 1, and the lower surface of the outer peripheral portion 7 of the base plate 5 is attached to the peripheral edge of the upper surface opening of the container body 1 by an O-ring. It is placed via a seal member 3 such as a metal gasket or a metal gasket. In this state, the bolt 4 penetrating the outer peripheral portion 7 from above is fastened and fixed to the peripheral edge portion of the upper opening of the container body 1. As a result, the base plate 5 is assembled to the container body 1. In this assembled state, a refrigerant flow path sealed by the container body 1 and the base plate 5 is formed, and the heat radiation fins 6 are arranged in the refrigerant flow path.

In this assembled state, the lower ends of the radiation fins 61 may be in contact with the inner bottom surface of the container body 1.

Further, the mounting substrate 2 as a cooling target member is provided above the inner peripheral portion 6 of the base plate 5. The mounting board 2 includes an insulating plate 21 formed of a ceramic plate or the like, and wiring layers 22 and 22 made of aluminum are laminated on the upper and lower surfaces of the insulating plate 21 with a brazing material or the like, and the upper wiring layer is formed. A power semiconductor element 24 is fixed to the upper surface of 22 via a solder layer 23.

The lower wiring layer 22 of the mounting board 2 is bonded to the upper surface of the inner peripheral portion 6 of the base plate 5 by brazing, welding, adhesive coating, or the like. As a result, the semiconductor device of this embodiment is formed.

In the present embodiment, the procedure for assembling the semiconductor device is not particularly limited. For example, the mounting board 2 may be assembled to the base plate 5 to form a semiconductor module, and the semiconductor module may be assembled to the container body 1. Alternatively, after the base plate 5 is assembled to the container body 1, the base of the container body 1 is assembled. The mounting substrate 2 may be attached to the plate 5.

In the semiconductor device of the present embodiment having the above-described configuration, the container body 1 is provided with a refrigerant inlet and a refrigerant outlet (not shown), and the refrigerant flows into the container body 1 (refrigerant flow path) through the refrigerant inlet. After flowing through each of the plurality of heat radiation fins 61 in the refrigerant flow path, the refrigerant flows out from the refrigerant outlet. In this way, heat exchange between the refrigerant flowing through the container body 1 (refrigerant flow path) and the semiconductor element 24 causes heat generated from the semiconductor element 24 to be radiated to the outside through the refrigerant, and The element 24 is adapted to be cooled. In this embodiment, a cooling fluid such as cooling water is used as the refrigerant.

According to the semiconductor device of the first embodiment having the above-described configuration, the base plate 5 is divided into the inner peripheral portion 6 and the outer peripheral portion 7, and the space between them is connected by the buffer portion 8 having low strength. Even if the semiconductor module such as the base plate 5 and the mounting substrate 2 is cooled by the operation of the container 1, and the outer peripheral portion 7 of the base plate 5 is thermally contracted to generate an inward stress F in the outer peripheral portion 7, the stress F is generated. F is absorbed by the deformation of the buffer portion 8. Therefore, it is possible to avoid the adverse effect due to the heat shrinkage of the outer peripheral portion 7. For example, it is possible to prevent a problem in which the insulating plate 21 of the mounting substrate 2 is warped due to the stress F generated when the outer peripheral portion 7 is thermally contracted, and the semiconductor element 24 and the wiring layer 22 of the insulating plate 21 due to the warping can be prevented. It is possible to prevent contact failure, prevent the occurrence of operation failure and deterioration of heat dissipation performance, and it is possible to reliably prevent problems such as breakage and damage of the insulating plate, and maintain good insulation performance. ..

More specifically, when the base plate 105 is formed as an integral component as in the semiconductor device of the reference example corresponding to the related art shown in FIG. 4, an inward stress F due to thermal contraction is generated in the base plate 105. Since the insulating plate 21 of the mounting board 2 has a smaller thermal contraction rate than the base plate 105, the insulating plate 21 cannot absorb the stress F, and the mounting board including the insulating plate 21 as indicated by an imaginary line L in FIG. A mountain warp occurs such that the central portion of the whole 21 rises upward. Then, the semiconductor element 24 or the insulating plate 21 may have a poor contact with the wiring layer 22 or the like, resulting in a malfunction or a decrease in heat dissipation performance. May be damaged. In addition, in the configuration of the semiconductor device of the reference example of FIG. 4, parts corresponding to the configuration of the semiconductor device of the first embodiment shown in FIG.

On the other hand, in the present embodiment, as described above, since the stress F due to the heat shrinkage of the base plate 5 is absorbed by the deformation of the buffer portion 8, it is possible to avoid the adverse effect of the stress F on the mounting substrate 2. it can.

Further, in the base plate 5 of the semiconductor device of the present embodiment, the inner peripheral portion 6 in which the heat radiation fins 61 are formed is made of a material having a high thermal conductivity, so that the heat generated from the semiconductor element 24 is generated in the inner peripheral portion. It is smoothly absorbed by the refrigerant in the container body 1 via 6, heat exchange can be efficiently performed, and sufficient cooling performance can be obtained.

Further, in the present embodiment, the outer peripheral portion 7 of the base plate 5 fixed to the container body 1 is made of a material having high strength, and therefore the outer peripheral portion 7 is also deformed by the elastic repulsive force of the seal member 3. Therefore, the outer peripheral portion 7 can be reliably attached to the container body 1 in a state where the seal member 3 is compressed. Therefore, the outer peripheral portion 7 serving as the base plate 5 can be attached to the container body 1 in a stable state with high positional accuracy while sufficiently ensuring the hermeticity, and the product value can be significantly improved.

In the present embodiment, for example, when the thickness of the inner peripheral portion 6 of the base plate 5 is made smaller than the thickness of the outer peripheral portion 7, the heat transfer coefficient of the inner peripheral portion 6 can be further improved, and cooling can be performed. The performance can be further improved, the strength of the outer peripheral portion 7 can be further improved, and the base plate 5 can be attached to the container body 1 in a more stable state.

<Second Embodiment>
FIG. 2 is a cross-sectional view showing a power semiconductor device to which a cooler according to a second embodiment of the present invention is applied, and FIG. 3 is a cross-sectional view showing an enlarged periphery of a buffer portion in the semiconductor device.

As shown in both figures, in this semiconductor device, a bent portion 81 is formed by bending a middle portion of the buffer portion 8 connecting the inner peripheral portion 6 and the outer peripheral portion 7 of the base plate 5 into a V-shaped cross section. Has been done. The tip (valley bottom) of the bent portion 81 is configured as a deformation starting point.

Since the other configurations of the semiconductor device of the second embodiment are substantially the same as those of the first embodiment, the same or corresponding parts will be denoted by the same reference symbols and redundant description will be omitted.

Also in the semiconductor device of the second embodiment, the same operational effects as above can be obtained. Furthermore, in the semiconductor device of the second embodiment, the stress F generated in the outer peripheral portion 7 of the base plate 5 due to heat contraction is absorbed by the deformation of the buffer portion 8 as in the above, but at the time of the deformation, the buffer portion The V-shaped bent portion 81 of FIG. 8 serves as a deformation starting point, and the bent portion 81 is deformed from the state of FIG. 3(a) so that the bending angle is reduced to the state of FIG. 3(b). Become. As described above, in the second embodiment, since the bent portion 81 of the buffer portion 8 starts to be deformed smoothly and reliably, the stress F generated in the outer peripheral portion 7 can be reliably absorbed even if the stress F is small. Therefore, it is possible to more reliably avoid the adverse effect of thermal expansion and contraction of the base plate 5, and it is possible to further improve reliability.

<Modification>
In the above-described embodiment, the cooler that cools the semiconductor element 24 (mounting substrate 2) has been described as an example, but the invention is not limited to this. In the present invention, the member to be cooled (member to be cooled) is mounted. The invention is not limited to the substrate, and can be applied to a cooler that cools a member to be cooled (heating element or the like) other than the mounting substrate (semiconductor element).

Further, in the above embodiment, the case where the base plate is fixed to the container body by the bolt has been described as an example, but the present invention is not limited thereto, and in the present invention, the fixing means for the base plate to the container body is not limited. Absent. For example, instead of bolts, fixing means such as screws or clamps may be used for fixing.

The cooler of the present invention can be suitably used as a cooling device for cooling a member to be cooled such as a mounting substrate on which a power semiconductor element is mounted.

1: Container body (jacket)
11: Top surface opening 2: Mounting board (member to be cooled)
21: insulating plate 24: semiconductor element 5: base plate 6: inner peripheral part 7: outer peripheral part 8: buffer part 81: bent part S: gap

Claims (8)

A box-shaped container main body having an opening on the upper surface, and a base plate on which an object to be cooled can be arranged on the upper surface side of the inner peripheral portion, the lower surface side of the outer peripheral portion of the base plate is the upper opening peripheral edge portion of the container main body. By being fixed, the base plate is a cooler assembled to the container body so as to close the upper surface opening,
The inner peripheral portion of the base plate is formed separately from the outer peripheral portion via a gap, and the inner peripheral portion and the outer peripheral portion have a lower strength than the inner peripheral portion and the outer peripheral portion. A cooler characterized in that it is connected via a section. The cooler according to claim 1, wherein a bent portion having a V-shaped cross section is formed in the buffer portion. The cooler according to claim 1 or 2, wherein the outer peripheral portion of the base plate is formed of a material having higher strength than the inner peripheral portion. The cooler according to claim 1, wherein the inner peripheral portion of the base plate is formed of a material having a higher thermal conductivity than the outer peripheral portion. The cooler according to claim 1, wherein the outer peripheral portion and the inner peripheral portion of the base plate are made of aluminum. A box-shaped container body having an opening on the upper surface, a base plate of a cooler assembled so as to close the upper opening,
An inner peripheral portion on which the cooling target member can be arranged on the upper surface side,
An outer peripheral portion that is provided outside the inner peripheral portion and that can be fixed to the upper surface opening edge portion of the container main body on the lower surface side,
The inner peripheral portion is formed separately from the outer peripheral portion via a gap, and the inner peripheral portion and the outer peripheral portion are interposed via a buffer portion having lower strength than the inner peripheral portion and the outer peripheral portion. A base plate of a cooler characterized by being connected. A box-shaped container body having an opening on the upper surface, a base plate whose lower surface side of an outer peripheral portion is fixed to a peripheral portion of the upper surface opening portion of the container body to close the upper surface opening portion of the container body, and an inner periphery of the base plate. A semiconductor device arranged on the upper surface side of the part and including a mounting substrate including a semiconductor element,
The inner peripheral portion of the base plate is formed separately from the outer peripheral portion via a gap, and the inner peripheral portion and the outer peripheral portion have a lower strength than the inner peripheral portion and the outer peripheral portion. A semiconductor device, characterized in that the semiconductor devices are connected via parts. The semiconductor device according to claim 7, wherein the mounting substrate includes an insulating plate, and the semiconductor element is arranged above the insulating plate.

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