JP2003007928A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device superior in heat dissipation performance from a semiconductor module to a cooler. SOLUTION: The semiconductor device is provided with the semiconductor module M where bus bars 11 and 12 on which semiconductor elements 21 and 22 are mounted by face-bonding, a bus bar 13 are integrated by a resin frame 1, and the semiconductor element 22 is sealed by filling an area S where semiconductor element is arranged with a gel member 4 so as to harden it; and with the cooler 2 where the semiconductor module M is fixed across a heat radiating sheet 3. A hole 100 passing from the area S where semiconductor element is arranged to a part facing the heat radiating sheet 3 of the semiconductor module M is formed in the connection part 1c of the resin frame 1. Consequently, the gel member 4 of the area S where semiconductor element is arranged intrudes into the gap among the bus bar 11, the bus bars 12 and 13 and the heat radiating sheet 3 through the hole 100.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor module in which a plurality of bus bars on which semiconductor elements are mounted are integrated by resin molding and the semiconductor elements are sealed with a sealing agent such as gel with a heat radiating sheet sandwiched therebetween. The present invention relates to a semiconductor device attached to a cooler.

[0002]

2. Description of the Related Art Semiconductor devices such as an inverter for converting DC power into AC power by using semiconductor elements such as transistors, IGBTs and thyristors, and a converter for converting AC power into DC power are known. In these semiconductor devices, the amount of heat released from the semiconductor element increases as the power increases, and it is necessary to attach a cooler to the semiconductor element for cooling.

For example, a power converter for converting DC P, N into AC U, V, W using an IGBT and a diode,
That is, in the power conversion circuit of the inverter, the semiconductor element (IGBT, diode) is directly connected to the bus bar by soldering. As the bus bar, for example, a sheared copper plate is used. The bus bars provided with the semiconductor elements are arranged at intervals from each other, and are molded with resin to be integrated so as to ensure electrical insulation. Normally, as a measure against heat generation of semiconductor elements, the bus bar integrated with resin is connected to the heat sink via a heat dissipation sheet, and the back surface of each bus bar (that is, the surface on which the semiconductor element is not provided) and the heat dissipation sheet make surface contact It has a structure that

[0004]

However, the surfaces of the bus bar and the heat radiating sheet have fine irregularities when observed microscopically, and can be strictly regarded as a collection of point contacts rather than surface contacts. Then, air having a small thermal conductivity is present in the gap where they are not in contact with each other. As a result, there is a problem that the thermal conductivity from the bus bar to the heat sink decreases.

An object of the present invention is to provide a semiconductor device in which a semiconductor module is attached to a cooler with a heat-dissipating sheet sandwiched between the semiconductor module and the cooler.

[0006]

An embodiment of the invention will be described with reference to FIGS. 2, 3, 8 and 9. (1) Explaining in association with FIG. 2 and FIG. 3, the invention of claim 1 uses a resin mold member 1 to form a plurality of busbars 11 and 12 on which semiconductor elements 21 and 22 are mounted by surface bonding and a busbar 13. The semiconductor module M, which is integrated, seals the semiconductor elements 21 and 22 by filling the liquid sealing agent 4 in the semiconductor element disposition region S and curing the same, and fixes the semiconductor module M with the heat dissipation sheet 3 interposed therebetween. The present invention is applied to a semiconductor device including a cooler 2 and achieves the above-mentioned object by forming at least one hole 100 penetrating from the semiconductor element disposition region S to a portion of the semiconductor module M facing the heat dissipation sheet 3. . (2) The invention of claim 2 is the semiconductor device according to claim 1, wherein the hole 100 is formed in the resin mold member 1c included in the semiconductor element disposition region S. (3) Describing in association with FIG. 8, the invention of claim 3 is the semiconductor device according to claim 2, wherein the resin mold member 1c has a protrusion 11 whose height H is higher than that of the semiconductor element.
0 is formed, and the hole 100 is formed in the protrusion 110. (4) Describing in association with FIG. 9, the invention of claim 4 is the semiconductor device according to claim 3, wherein the protrusion 11 is provided.
The height H of 0 is higher than the surface of the sealant 4.

In the section of the means for solving the above problems, the drawings of the embodiments of the present invention are used to make the present invention easy to understand, but the present invention is limited to the embodiments of the present invention. Not something.

[0008]

(1) According to the invention of claim 1, the liquid sealing agent filled in the semiconductor element disposition region is guided to the heat dissipation sheet side of the semiconductor module through the hole, and the semiconductor module and the heat dissipation sheet are connected. Penetrate the gap. As a result, the gap between the semiconductor module and the heat dissipation sheet is filled with the sealing member to reduce the gap space, so that the heat dissipation performance from the semiconductor module to the cooler is improved. (2) In the invention of claim 2, the same effect as in claim 1 is obtained, and since the hole is formed in the resin mold member, it is possible to easily form the hole without considering the current path. (3) According to the invention of claim 3, the same effects as those of claims 1 and 2 are obtained, and since the height of the protruding portion is higher than that of the semiconductor element, bubbles discharged from the holes during filling of the liquid sealing agent are Does not adhere to semiconductor elements. As a result, the sealing effect of the semiconductor element by the sealing member does not decrease. (4) According to the invention of claim 4, the same effects as those of claims 1 and 2 are obtained, and the bubbles discharged from the holes at the time of filling the liquid encapsulant are contained in the liquid encapsulant in the semiconductor element disposition region. It is directly discharged to the outside of the liquid sealant without being discharged. As a result, it is possible to reliably prevent bubbles from adhering to the semiconductor element.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a part of a power converter circuit of an inverter that converts direct current P, N into alternating current U, V, W by using semiconductor elements 21, 22. It shows a portion related to a phase component, for example, a U phase. In the example shown in FIG. 1, the semiconductor elements 21 and 22 are
MOS FET is used. 11 is a bus bar for P pole,
12 is a bus bar for inverter output, and 13 is a bus bar for N pole. Further, 51, 52 are semiconductor elements 21,
22 is a gate terminal for applying a drive signal to each gate G of 22.

FIG. 2 is a perspective view showing the structure of the circuit shown in FIG. The semiconductor element 21 is fixed on the bus bar 11 with a conductive bonding material 31.
The back surface (drain D in FIG. 1) of the above is surface-bonded to the front surface of the bus bar 11 for the P pole. Similarly, the semiconductor element 22 is fixed on the inverter output bus bar 12 by the bonding material 32, and the back surface of the semiconductor element 22 (drain D in FIG. 1) and the front surface of the bus bar 12 are surface-bonded. Bonding material 3
1, 32 are semiconductor elements 21, 22 and bus bars 11, 1
The two are electrically connected and also play a role of thermal connection, and solder or the like is used. The bonding material 3
In addition to solder, conductive paste containing silver filler or the like may be used as 1, 32.

The sources S and the gates G of FIG. 1 are formed on the upper surfaces of the semiconductor elements 21 and 22 in the figure, and the source of the semiconductor element 21 is the metal wire 41 for the bus bar 12.
, And the gate is connected to the gate terminal 51 by a metal wire 61. A signal for driving the semiconductor element 21 is input to the gate terminal 51. On the other hand, the semiconductor element 22
The source is connected to the bus bar 13 by the metal wire 42, and the gate is connected to the gate terminal 52 by the metal wire 62.

Since the bus bars 11 to 13 have different electric potentials, they are arranged at intervals so as not to contact each other. 1
Is molded with an electrically insulative resin so as to cover the edge portions of the bus bars 11 to 13 and fill the spaces between the bus bars 11 to 13, and will be referred to as a resin frame 1 below. Note that, in FIG. 2, a part of the resin frame 1 has a fracture surface. With this resin frame 1, a plurality of bus bars 11 to 13
Are joined together to form an integral module M.
The resin frame 1 also has a function of electrically insulating between the bus bars 11 to 13.

The integrated module M is fixed to the heat sink 2 via the heat dissipation sheet 3. A flow path 2a through which a coolant such as cooling water flows is formed in the heat sink 2. The heat dissipation sheet 3 plays a role of transferring the heat transferred from the semiconductor elements 21 and 22 to the busbars 11 and 12 to the heatsink 2 and ensuring electrical insulation between the busbars 11 and 12 and the heatsink 2. . The heat generated in the semiconductor elements 21 and 22 is transferred to the bus bars 11 and 12
The heat is also transmitted to the heat sink 2 via the heat dissipation sheet 3 and is radiated to the refrigerant flowing through the flow path 2a.

A wall 1a is formed in the resin frame 1 so as to surround the semiconductor elements 21 and 22, and a semiconductor mounting region S surrounded by the wall 1a is filled with a gel member 4 as a sealing member. The gel member 4 is not shown in FIG. FIG. 3 is a sectional view taken along the line AA of FIG. 2, in which the gel member 4 is filled up to the vicinity of the upper end of the wall 1a. As a result, the semiconductor element 2
1, 22 and the metal wires 41, 42, 61, 62 are sealed in the gel member 4 to protect the semiconductor elements 21, 22 and
The resonance of the aerial wiring portion of the metal wires 41, 42, 61, 62 can be prevented.

As shown in FIG. 3, in addition to the wall 1a described above, the resin frame 1 includes the connecting portions 1b and 1c between the bus bars and the wall 1.
It has a flange portion 1d extending to the outside of a. The bottom surfaces of the bus bars 11 to 13 project below the bottom surfaces of the connecting portions 1b and 1c and the flange portion 1d in the drawing, and the bottom surfaces of the bus bars 11 to 13 are in contact with the heat dissipation sheet 3. In addition, a through hole 100 is formed in the connecting portion 1c, and the gel member 4 passes through the hole 100 to form a gap between the bottom surface of the connecting portion 1c and the heat dissipation sheet 3, and further the bus bars 11 to 13.
Also penetrates into the minute gap between the bottom surface of the heat radiation sheet 3 and the heat radiation sheet 3.

FIG. 4 is an enlarged view of portion B of FIG. 3, and FIG. 5 is a further enlarged view of portion C of FIG. As described above, since the surfaces of the bus bars 11 to 13 have microscopic unevenness, a minute gap is formed between the bottom surface of the bus bar and the heat dissipation sheet 3 as shown in FIG. In the present embodiment, the liquid gel member 4 is formed in the hole 10 formed in the connecting portion 1c.
0, and enters into the gap between the connecting portion 1c and the heat dissipation sheet 3 (see FIG. 4), and further, the gel member 4 penetrates into the gap 5 between the bus bar 11 and the heat dissipation sheet 3 (see FIG. 5). On the other hand, in the conventional case, since the through hole is not formed in the connecting portion 1c, the gap 5 between the bus bar 11 and the heat dissipation sheet 3 in FIG. 5 is an air layer. The thermal conductivity of air is 0.0
Although it is 3 (W / m · K), the thermal conductivity of the gel member 4 is higher than that, for example, 0.15 (W / m · K). Therefore, the gap 5 between the bus bar 11 and the heat dissipation sheet 3
By introducing the gel member 4 into the heat sink 2, heat dissipation performance from the bus bar 11 to the heat sink 2 can be improved.

<< Explanation of Gel Member Filling Procedure >> FIGS. 6 and 7 are views for explaining the procedure of the filling operation of the gel member 4. Figure 6
As shown in (a), a plurality of through holes 17 for screw fixing are formed in the flange portion 1d of the resin frame 1, and the module M is screw-fixed to the heat sink 2 using the through holes 17. 14 is a gel filling jig in which a module mounting screw hole 19 is formed. The module M is attached to the jig 14 so that the heat radiation sheet 3 is sandwiched by the screws 16 as in the case of attaching to the heat sink 2. At this time, the screws 16 are tightened so that the bottom surfaces of the bus bars 11 to 13 are pressed by the heat dissipation sheet 3. The heat dissipation sheet 3 also has through holes 18 formed at positions corresponding to the through holes 17.

Next, as shown in FIG. 6B, the gel member 4 is filled in the inner space of the semiconductor element disposition region S surrounded by the wall 1a using the dispenser 15. The gel member 4 contains silicone as a main component, and is a low-viscosity liquid in a sol state at the time of filling. After the filling, the gel is hardened from the sol state by leaving it at room temperature or high temperature for a certain time. The filled gel member 4 penetrates into the gap 5 (see FIG. 5) between the bus bars 11 to 13 and the heat dissipation sheet 3 through the hole 100 of the connecting portion 1c.

Next, as shown in FIG. 7A, the module M filled with the gel member 4 is loaded into the vacuum furnace 30 while being fixed to the jig 14, and the inside of the vacuum furnace 30 is vacuum pumped.
Evacuate at 4. As a result, the air present in the gaps between the bus bars 11 to 13 and the heat radiation sheet 3 is discharged from the gap 36 between the flange portion 1d and the heat radiation sheet 3 and also discharged as bubbles 35 from the holes 100 of the connecting portion 1c. To be done. The liquid gel member 4 having a low viscosity enters the gap where the air is discharged.

Thereafter, the temperature inside the vacuum furnace 30 is set to 1 at maximum.
The temperature is raised to 50 ° C. and the gel member 4 is gel-hardened. The furnace temperature and the standing time at this time are set according to the curing conditions of the gel member 4. When the gel member 4 is gel-hardened, the screw 16 is removed and the module M is removed from the jig 14 as shown in FIG. 7B. Since the gel member 4 penetrates into the gaps between the heat dissipation sheet 3 and the bus bars 11 to 13, the heat dissipation sheet 3 and the module M are integrated with each other by the van der Waals force and the anchor effect using the gel member 4 as a medium.

As described above, in the present embodiment, the through hole 100 is formed in the connecting portion 1c of the resin frame 1, and the gel member 4 filled in the semiconductor element disposition region S surrounded by the wall 1a.
By infiltrating into the gap between the bus bars 11 to 13 and the heat dissipation sheet 3, the heat dissipation performance from the bus bars 11 to 13 to the heat sink 2 can be improved. Further, by placing the module M filled with the gel member 4 in a vacuum atmosphere, the air intervening in the gap 5 is discharged, and the gel member 4 can be surely infiltrated into the gap 5.

Further, as shown in FIG. 7A, the through hole 1
Since 00 is formed avoiding the portion where the metal wire 42 is provided, the bubbles 35 discharged during evacuation
Does not adhere to the metal wire 42. For example, when the gel member 4 is gel-hardened with the bubbles 35 attached to the metal wire 42, the portion to which the bubbles 35 are attached becomes a void without the gel member 4. Therefore, if the bubbles 35 adhere to the metal wire 42, the metal wire 42 may be insufficiently fixed or the resonance may be prevented. However, in the present embodiment, such an inconvenience can be avoided.

[Modification 1] FIG. 8 is a first modification of the above-described embodiment and is a sectional view taken at the same position as in FIG. A columnar portion 110 is formed in the connecting portion 1c, and a hole 100 is formed so as to penetrate the columnar portion 110 and the connecting portion 1c. When the depth H of the gel member 4 is D1 and the height of the semiconductor element 22 is H1, the height H of the columnar portion 110 is
It is set so that H1 <H <D1. Preferably,
About the same as D1 is good. The columnar portion 1 having such a height H
The hole 100 is formed in the hole 10 and the outlet of the hole 100 is near the surface of the gel member 4, so that the hole 10 can be removed during vacuuming.
The bubbles discharged from 0 are the semiconductor element 22 and the metal wire 4
It can be prevented from adhering to 2.

Further, as shown in FIG. 9, the height H of the columnar portion 110 in which the hole 100 is formed may be made larger than the depth D1 of the gel member 4. When the gel member 4 is filled, the dispenser 1 is placed so that the discharge port 15 a is directly above the hole 100.
5 is positioned and filling is performed. The gel member 4 flows into the holes 100 and fills the semiconductor element disposition region S as well. In the case of FIG. 9, the bubbles discharged from the hole 100 are directly discharged to the external space without being discharged to the gel member 4 in the semiconductor element housing space. Therefore, it is possible to reliably prevent air bubbles from adhering to the semiconductor element 22 and the metal wire 42, and to consider the distance from the hole 100.
The layout of the metal wire 42 can be designed.

[Modification 2] FIG. 10 is a view showing a second modification and is a perspective view similar to FIG. The heat sink 2 is not shown in FIG. In the module M of FIG. 2 described above, the hole 100 was formed only at one place of the connecting portion 1c, but in the module M2 of FIG. 10, the hole 100 was formed at a plurality of places of each connecting portion 1b, 1c.
However, it is formed in the portion excluding the positions directly under the metal wires 41, 42. Also in this case, the columnar portion 1 as shown in FIGS.
A plurality of 10 may be formed and the through hole 100 may be formed in each columnar portion 110. By forming a plurality of through holes 100 in this manner, it becomes easy for the gel member 4 to penetrate into the entire bottom surfaces of the bus bars 11 to 13. In addition, the path of the air discharged from the gap 5 (see FIG. 5) during evacuation is shortened, and the air can be discharged efficiently,
The work time for vacuuming can be shortened.

In the above-described embodiment, the through hole 100 is formed in the resin frame 1 which insulates the bus bars from each other for the following reasons (a) and (b). (A) With the resin frame 1, the through holes 100 can be easily formed when the resin frame 1 is molded. (B) With the resin frame 1, it is not necessary to consider the current path.

However, for the purpose of guiding the gel member 4 into the gap between the bus bars 11 to 13 and the heat dissipation sheet 3, it is not always necessary to form the through hole 100 in the resin frame 1. For example, the semiconductor elements 21 and 22 and the metal wire 4
The through holes 100 may be formed in the bus bars 11 to 13 as long as they do not affect the positions 1, 42, 61 and 62.

Although the present invention has been described by taking the circuit for one phase of the inverter circuit as an example, a plurality of bus bars on which semiconductor elements are mounted are resin-molded and integrated, and the gel member 4 is provided in the semiconductor element mounting region S. If it has a structure for filling the

In the correspondence between the embodiment described above and the elements in the claims, the resin frame 1 constitutes a resin mold member, the gel member 4 constitutes a liquid sealant, and the columnar portion 100 constitutes a protruding portion. .

[Brief description of drawings]

FIG. 1 is a diagram showing a part of a power conversion unit circuit of an inverter.

FIG. 2 is a diagram showing an embodiment of a semiconductor device according to the present invention, and is a perspective view showing the structure of the circuit shown in FIG.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is an enlarged view of part B shown in FIG.

5 is an enlarged view of a C portion shown in FIG.

FIG. 6 is a diagram showing a procedure of a filling operation of the gel member 4,
The work proceeds in the order of (a) and (b).

FIG. 7 is a diagram showing a work procedure following FIG. 6, (a),
The work proceeds in the order of (b).

FIG. 8 is a sectional view showing a first modification.

9 is a height H of the columnar part 100 in the first modification. FIG.
FIG. 6 is a cross-sectional view showing a case where is larger than the depth D1 of the gel member 4.

FIG. 10 is a perspective view showing a second modified example.

[Explanation of symbols]

1 resin frame 1a wall 1b, 1c connection part 1d flange 2 heat sink 3 heat dissipation sheet 4 Gel member 5 gap 11,12,13 busbar 21,22 Semiconductor element 30 vacuum furnace 34 Vacuum pump 35 bubbles 41, 42, 61, 62 Metal wire 100 holes 110 Column M, M2 semiconductor module S Semiconductor element mounting area

Claims (4)

[Claims] 1. A semiconductor element is sealed by integrating a plurality of bus bars on which semiconductor elements are mounted by surface bonding with a resin mold member and filling a liquid sealing agent in a semiconductor element arrangement region and curing the liquid sealing agent. A semiconductor module,
In a semiconductor device having a cooler in which the semiconductor module is fixed with a heat dissipation sheet sandwiched, at least one hole penetrating from the semiconductor element disposition region to a portion of the semiconductor module facing the heat dissipation sheet is formed. A semiconductor device characterized by the above. 2. The semiconductor device according to claim 1, wherein the hole is formed in the resin mold member included in the semiconductor element disposition region. 3. The semiconductor device according to claim 2, wherein a protrusion having a height higher than that of the semiconductor element is formed on the resin mold member, and the hole is formed in the protrusion. apparatus. 4. The semiconductor device according to claim 3, wherein the height of the protrusion is higher than the surface of the sealant.