JP2000174197A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb a mechanical stress according to a difference of thermal expansion coefficients or a vibration and to effectively maintain an electric connection of an electrode plate to a conductive circuit, by sandwiching a board relatively sliding in a range limited to the plate and a heat sink between the plate and the sink. SOLUTION: A frame 12 made of an insulating material such as a synthetic resin or the like having an opening 13 is clamped on a heat sink 7. The opening 13 is formed in a rectangular shape by disposing four control pins 11 arranged in one row at both ends in the longitudinal direction. A length of the opening of a direction perpendicular to an arraying direction of the pins 11 is formed slightly longer than a length in the longitudinal direction of boards 5. The boards 5 are disposed in the frame 12 slidably to the sink 7 in a range limited by the pins 11 and the opening 13. Thus, an electric connection of the plate to a conductive circuit can be effectively maintained, and a mechanical stress caused by a difference of thermal expansion coefficients of the plate, the board and the sink or a vibration can be absorbed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device in which a substrate on which a semiconductor chip is mounted is mounted on a heat sink.

[0002]

2. Description of the Related Art A structure in which a substrate having a semiconductor chip is mounted on a heat sink is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-9048.
As is already known from Japanese Patent Application Publication No. 7-107, etc., in such a conventional semiconductor device, a substrate is fixed to a heat sink, and an electrode plate connected to a conductive circuit on the substrate is also fixed to the heat sink.

[0003]

However, when the positions of the substrate and the electrode plate with respect to the heat sink are fixed, as in the conventional case, mechanical stress caused by the difference in the coefficient of thermal expansion between the electrode plate, the substrate and the heat sink. Also, mechanical stress due to vibration may occur, and a good conduction state between the electrode plate and the conductive circuit may not be obtained.

The present invention has been made in view of such circumstances, and has as its object to provide a semiconductor device capable of obtaining good heat conduction while maintaining good conduction between a conductive circuit and an electrode plate. And

[0005]

In order to achieve the above object, the present invention provides a substrate having a conductive circuit formed on a surface thereof, and a semiconductor electrically connected to the conductive circuit and fixed on the substrate. In a semiconductor device including a chip and a heat sink on which the substrate is mounted, an electrode plate in contact with the conductive circuit is fixed to the heat sink, and the substrate relatively slides in a limited range with respect to the electrode plate and the heat sink. Preferably, the substrate is sandwiched between an electrode plate and a heat sink.

According to such a structure, the substrate sandwiched between the electrode plate and the heat sink can move within a limited range in a state where the electrode plate is in contact with the conductive circuit of the substrate. In addition, it is possible to reliably maintain the electrical connection of the electrode plate to the conductive circuit while absorbing the mechanical stress due to the difference in the coefficient of thermal expansion of the heat sink and the mechanical stress due to vibration. Moreover, the mutual contact portion between the electrode plate and the conductive circuit is cleaned by a self-cleaning action accompanying the relative sliding of the electrode plate and the substrate.
Good conduction of the electrode plate to the conductive circuit can be maintained, and good heat conduction can be obtained.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 3 show one embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a semiconductor device, and FIG.
2 is an exploded perspective view of the semiconductor device, and FIG. 3 is a plan view of FIG.

First, in FIG. 1, this semiconductor device is configured as a power module for a three-phase motor, and is made of aluminum nitride that corresponds to each of U, V, and W phases in the motor. And five semiconductor chips 6 fixed on each of the substrates 5.
, And a heat sink 7 made of an aluminum alloy on which the substrates 5 are mounted in common.

Referring to FIG. 2 and FIG. 3 together, a surface of a substrate 5 formed in a rectangular shape having a thickness of 2 to 5 mm by aluminum nitride is provided with a conductive pattern patterned by metallization bonding of a copper plate. A circuit 8 is formed,
Each semiconductor chip 6 is joined to a predetermined position of the conductive circuit 8 by solder having a high melting point. In addition, both ends of conductive wires 9 such as aluminum wires are bonded to the respective semiconductor chips 6 and the conductive circuits 8 in order to achieve electrical connection between the semiconductor chips 6 and the conductive circuits 8.

The back surface of each substrate 5 is provided with a heat transfer grease 10.
Through the upper surface of the heat sink 7. On the upper surface of the heat sink 7, four regulating pins 11 spaced slightly larger than the width of each board 5 are planted in a line, and each board 5 is attached to each regulating pin 11. .. Are arranged so as to abut each other on the upper surface of the heat sink 7 via the heat transfer grease 10.

A frame 12 made of an insulating material such as a synthetic resin is fastened to the heat sink 7 with an opening 13, and the opening 13 is provided with four regulating members arranged in a line. The pins 11 are formed in a rectangular shape so as to be arranged at both ends in the longitudinal direction, and the length of the opening 13 in the direction orthogonal to the arrangement direction of the restriction pins 11 is
Are formed slightly longer than the length in the longitudinal direction. That is, each of the substrates 5 is arranged in the frame 12 so as to be able to slide with respect to the heat sink 7 within a range limited by each of the restriction pins 11 and the opening 13.

A portion connected to the positive side of the power supply in the conductive circuits 8 of the substrates 5 on both sides of the three substrates 5, and a portion connected to the positive side of the power supply in the conductive circuit 8 of the middle substrate 5 , The rectangular electrode plates 14, 14 extending between the adjacent substrates 5, 5 are in contact with each other, and one end thereof is in contact with a portion of the conductive circuits 8 of both substrates 5, connected to the positive side of the power supply. Rectangular electrode plates 15, 1
The other end of 5 protrudes laterally from both substrates 5, 5. The conductive circuits 8 of the substrates 5 on both sides of the three substrates 5.
The portion connected to the negative side of the power supply and the portion connected to the negative side of the power supply in the conductive circuit 8 of the middle substrate 5 are parallel to the electrode plates 14 and 14 between the adjacent substrates 5 and 5. Are in contact with each other, and the conductive circuits 8 of the substrates 5 on both sides are contacted.
, One end of which is in contact with a portion connected to the negative side of the power source, and the other ends of the rectangular electrode plates 17, 17 arranged in parallel with the electrode plates 15, 15 are on the opposite sides from the substrates 5, 5 on both sides. It is protruded toward. Further, the conductive circuits 8 of each substrate 5.
Electrode plates 1 whose one end is individually brought into contact with the output part of
8 protrude outward from one longitudinal end of each substrate 5. Moreover, the electrode plates 15 ..., 17 from each substrate 5 ...
, 18 ... cylindrical connecting portions 15a, 17a ..., 18a for fitting and connecting pin-shaped terminals.
... are provided.

Each of the above-mentioned electrode plates 14, 15, 16, 1.
, 18 ... are adhered to the back surface of an insulating sheet 19 formed in a rectangular shape with an insulating material such as insulating paper, and the other ends of the electrode plates 15 ..., 17 ..., 18 ... Projected outward from the

On the other hand, on the frame 12, steps 20, 20, which are continuous with both ends of the opening 13 in the direction along the arrangement direction of the respective restriction pins 11, put a part of the electrode plates 15,. And the insulating sheet 19 of the electrode plates 15.
Are formed in such a shape that the projecting portions from them are fitted together, and three step portions 21 connected to one side of the opening 13 in a direction orthogonal to the arrangement direction of the respective restriction pins 11 are formed on the electrode plate 1.
8 are formed in such a shape that the protruding portions from the insulating sheet 19 are fitted and placed.

The insulating sheet 19 is provided with three windows 22 through which most of the substrates 5 are exposed.
Are sandwiched between four metal holding plates 23
Are adhered to the surface of the insulating sheet 19. These holding plates 23 are provided with a pair of insertion holes 24, 25 at positions sandwiching each of the restriction pins 11 and are inserted through one of the insertion holes 24 so that the insulating sheet 19 is inserted. The bolts 26 penetrating between the electrode plates 15 and 17 and the electrode plate 1
The bolts 27 which are screwed to the heat sink 7 between the holes 4 and 16 and which penetrate through the insulating sheet 19 by being inserted into the other insertion holes 25 and sandwiching the regulating pins 11 with the bolts 26. To the heat sink 7.

On the back surface of the insulating sheet 19, metal spacers 28 arranged on the left side of the bolts 27 in FIG. 3 are adhered. , 15 ..., 16 ..., 17 ..., 18 ...
Is set the same as The three bolts 28 except for the rightmost bolt 28 in FIG. 3 are arranged between the electrode plate 18 and the spacers 28, and the leftmost spacer 28 in FIG. The other spacers 28 abut on the step portions 20, but are in contact with the conductive circuits 8 on the surface of each substrate 5 so as not to perform an electrical connection function.

In this way, the electrode plates 14, 15, 16, 17 contacting the conductive circuits 8 on the surface of each substrate 5.
..., 18 ... are fixed to the heat sink 7.
Each substrate 5 is sandwiched between each of the electrode plates 14, 15, 16, 16, 17, 18, and the heat sink 7.
, Are electrode plates 14,..., 15,..., 16 in a range limited by each regulating pin 11 and the opening 13 of the frame 12.
, 17 ..., 18 ... and the heat sink 7 can be slid relative to each other.

Next, the operation of this embodiment will be described. The back surface of the aluminum nitride substrate 5 on which the conductive circuit 8 formed of a copper plate is formed is connected to the heat transfer grease 10.
, And the heat resistance between the substrate 5 and the heat sink 7 is smaller than that of the conventional one in which a copper plate, a solder layer and a copper base are interposed between the substrate and the heat sink. Therefore, even if the semiconductor chips 6 mounted on the substrates 5 are for power control as in this embodiment, sufficient heat radiation from the substrates 5 to the heat sink 7 can be obtained. Moreover, compared to a method in which the copper plate on the back surface of the substrate 5 and the copper base are joined by soldering over a relatively large area, soldering over a large area is unnecessary, so that a skilled technique is unnecessary, and assembly is not required. The number of work steps is also reduced.

Meanwhile, in a conventional device in which an aluminum nitride substrate is soldered on a copper base provided on a heat sink, the thickness of the substrate is 0.2 to 0.3 mm.
However, the thickness of the substrates 5 is set to 2 to 5 mm, and the heat capacity of the substrates 5 can be increased by increasing the thickness of the substrates 5 in this manner.
As a result, even if the copper base serving as a heat mass is abolished and the substrate 5 is mounted on the heat sink 7 via the heat transfer grease 10, the heat generated in the semiconductor chips 6 can be used by the copper base. It can be dissipated as well as the conventional one.

The electrode plates 14, 15, 16, 17, 18, 18 which are in contact with the conductive circuits 8 on the surface of the substrate 5 are fixed to the heat sink 7, and the electrode plates 14, 15, 1,
, 17 ..., 18 and the heat sink 7 can be slid relative to each other within a limited range, so that the substrates 5 ...
..., 18 ... and the heat sink 7,
The conductive circuit absorbs the mechanical stress caused by the difference in the coefficient of thermal expansion between the electrode plates 14, 15, 16, 17, 18, the substrate 5, and the heat sink 7 and the mechanical stress due to vibration. , Electrode plates 14 ..., 15 ..., 16 ...,
.., 18... Can be reliably maintained.

Moreover, the electrode plates 14, 15, 16, 1
, 18 and the conductive circuit 8 are cleaned by a self-cleaning action accompanying the relative sliding of the electrode plates 14, 15, 16, 17, 17, 18 and the substrate 5. Therefore, the electrode plates 14, 15, 16, 17
, 18 ... good heat conduction can be obtained while maintaining good conduction to the conductive circuits 8 ...

FIG. 4 shows a first modification of the electrode plates 14 to 18. The contact portions of the electrode plates 14 to 18 with the conductive circuit 8 are formed as substantially U-shaped projections 30 by press molding. As in the second modification shown in FIG. 5, a pair of protrusions 31 formed integrally with each of the electrode plates 14 to 18 may be in contact with the conductive circuit 8. As in a third modification shown in FIG.
A plurality of peaks 32 may be formed at the distal end of the electrode plate 31. Each of the electrode plates 14 to 18 may be bent toward the conductive circuit 8 as in a fourth modification shown in FIG. A large number of irregularities 34 may be formed by knurling on the surface on the conductive circuit 8 side of the contact portion 33 provided at one end of the contact plate 33. Further, as in a fifth modification shown in FIG.
A large number of irregularities 34 may be formed by knurling on the surface of the protrusion 30 provided on the conductive circuit 8 side of the protrusion 30.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible to do.

For example, in the above embodiment, the substrate 5 is made of aluminum nitride, but the substrate 5 may be formed of another non-conductive material.

[0026]

As described above, according to the present invention, the electrode plate,
By absorbing the mechanical stress due to the difference in the coefficient of thermal expansion between the substrate and the heat sink and the mechanical stress due to vibration, the electrical connection of the electrode plate to the conductive circuit can be reliably maintained, And good heat conduction can be obtained while maintaining good conduction to the conductive circuit.

[Brief description of the drawings]

1 is a longitudinal sectional view of the semiconductor device, and is a sectional view taken along line 1-1 of FIG. 3;

FIG. 2 is an exploded perspective view of the semiconductor device.

FIG. 3 is a plan view as viewed in the direction of arrow 3 in FIG. 1;

FIG. 4 is a side view of a main part of a first modification of the electrode plate.

FIG. 5 is a perspective view of a main part of a second modification of the electrode plate.

FIG. 6 is a perspective view of a main part of a third modification of the electrode plate.

FIG. 7 is a side view of a main part of a fourth modification of the electrode plate.

FIG. 8 is a side view of a main part of a fifth modification of the electrode plate.

[Explanation of symbols]

 5 ... substrate 6 ... semiconductor chip 7 ... heat sink 8 ... conductive circuit 14, 15, 16, 17, 18 ... electrode plate

Continued on the front page (72) Inventor Katsuhiko Iwasawa 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd. (72) Inventor Takahiko Hamada 1-10-1 Shinsayama, Sayama City, Saitama Honda Engineering Co., Ltd. Inside the company (72) Inventor Takeshi Ueda 1-10-1 Shinsayama 1 Sayama-shi, Saitama Honda Engineering Co., Ltd.

Claims (1)

[Claims] 1. A substrate (5) having a conductive circuit (8) formed on a surface thereof, and a semiconductor chip (6) electrically connected to the conductive circuit (8) and fixed on the substrate (5). And a heat sink (7) on which the substrate (5) is mounted, wherein the electrode plates (14, 15, 16, 17, 18) contacting the conductive circuit (8) are provided by the heat sink (7). To allow the substrate (5) to slide relative to the electrode plates (14-18) and the heat sink (7) within a limited range. ) And a heat sink (7).