JP3196540B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device called a power module in which a circuit board on which a semiconductor element is mounted is housed in a case frame, and more particularly to a structure for mounting a case frame and a heat radiation base plate.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 2 and 3, a semiconductor device (semiconductor module) called a power module or an intelligent power module includes a case frame 10 made of an insulating resin with a lead frame and a case frame 10 made of an insulating resin.
The heat radiation base plate (metal plate) 20 which is fixed to the opening step surface 14 on one side of the frame portion 12 with an adhesive to close the opening.
Circuit boards (ceramic substrates) 30 and 31 fixed to the inner surface of the heat dissipation base plate 20 by soldering or the like; and lead frames 40 to 45 in which the inner lead ends A are connected to thick film wiring on the circuit board 30. A large number of lead pins P1 to P1 are attached and fixed to the frame portion 12 of the case frame 10 and the inner lead ends B are connected to the thick film wiring on the circuit board 31.
Lead pin block 70 having P16 and case frame 1
0, and the inner leads and the lead pins P of the circuit boards 30, 31 and the lead frames 40 to 45 are filled.
A gel-like resin (silicone resin) sealing material 50 for immersing the inner leads 1 to P16 and an insulating resin made of an insulating resin for closing the opening by adhering to the opening step surface 18 on the other surface side of the case frame 10 with an adhesive. And a cover plate 60. Circuit board 30,
The semiconductor elements (chips) 32 and 34 such as power transistors, IGBTs (conductivity modulation type transistors), diodes, and thyristors are mounted on 31. The tips A of the inner leads of the lead frames 40 to 45 are
Is fixed to the thick film wiring (land portion) with solder or the like, and connected to the wiring and the corresponding semiconductor elements 32, 34 by bonding wires 32a, 34a. The lead frames 40 to 45 are embedded in the frame portion 12 by insert molding, and terminal screws (not shown) for external connection are screwed to the terminal seat plates 40 a to 45 a of the frame portion 12.

A semiconductor module having such a structure has a mounting seat 1 which is a thin portion at four corners of a case frame 10 made of an insulating resin.
A bolt (not shown) is inserted into a through hole 15a penetrating through the hole 5 and attached to an electronic device or the like. As shown in FIG. 4, the mounting hole 15 is formed in a metal cylindrical collar so that the edge of the through hole 15a and the mounting seat 15 do not suffer damage such as chipping or cracking due to the fastening with the through bolt. 15b is bordered by integral molding and embedding. For this reason, the through hole 15a is formed by the tightening force of the through bolt.
Even when the peripheral mounting seat 15 is sandwiched between the bolt head of the through bolt and the base plate 20, the metal tubular collar 15b reinforces, so that the mounting seat 15 is prevented from cracking.

[0004]

However, the above-described mounting structure of the case frame 10 made of insulating resin of the semiconductor module and the heat radiation base plate 20 has the following problems.

An adhesive 15c is applied to the stepped surface 14 of the insulating resin case frame 10 including the back surface of the mounting seat 15, and a metal base plate 20 is attached to close the opening. However, even if the amount of the adhesive 15c is optimized and applied by an automatic application machine, the thickness t of the adhesive layer varies depending on the bonding force of the base plate 20. If the bonding force is too strong, the adhesive 15c sandwiched between the step surface 14 and the base plate 20 excessively protrudes, so that the layer thickness t becomes too thin, and the adhesive layer peels off or gels after drying. There is a possibility that the resin sealing material may leak. If the bonding force is too weak, the layer thickness t is large because voids and the like remain in the film, but the adhesive layer is crushed by the tightening force of the through bolt when the semiconductor module is mounted on equipment or the like. Be deformed. As a result, the fastening force of the bolt acts as a bending moment on the mounting seat 15 made of resin, and the mounting seat 15 may be cracked.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to improve the mounting structure between a case frame and a base plate in a semiconductor module, thereby eliminating variations in the thickness of the adhesive layer and optimizing the adhesive. An object of the present invention is to prevent peeling of a layer, leakage of a gel resin sealing material, cracking of a mounting seat, and the like.

[0007]

In order to solve the above-mentioned problems, the means of the present invention is to use the metallic tubular collar itself as a spacer for defining the thickness of the adhesive layer. That is, the present invention provides a case frame made of an insulating resin in which a lead frame extends from a frame portion, a metal heat dissipation base plate fixedly closed with an adhesive on one of the step surfaces of the case frame with an adhesive, A circuit board fixed with an inner surface of the heat radiation base plate and mounted with a semiconductor element connected to a tip of an inner lead of the lead frame, and an inner space of the case frame is filled, and the circuit board and the inner lead are immersed therein. A gel-like resin sealing material, a cover plate made of an insulating resin for closing the other opening of the case frame, and a metal cylindrical shape for a through hole embedded in the mounting seat at the four corners of the case frame by integral molding. in a semiconductor device having a color, metallic cylinder end surface of the metallic, cylindrical collar has issued the projecting from the coated by the opening stepped surface level of the adhesive by a predetermined length, projecting
When the end face of the collar contacts the heat dissipation base plate,
Formed between the opening step surface and the heat dissipation base plate.
The adhesive is interposed in the formed gap . This gap is desirably 0.1 to 0.2 mm .

[0008]

According to the present invention, the adhesive is applied to the step surface of the opening of the case frame, and then the metal frame is bonded to the base plate by bonding a metal heat dissipation base plate. Protruding from the level of the step surface by a predetermined length , this
The end of the protruding metal cylindrical collar abuts the heat dissipation base plate
Between the step surface of the opening and the heat dissipation base plate.
Since the adhesive is interposed in the formed gap ,
An adhesive layer having a thickness corresponding to this gap is secured, and the thickness of the adhesive layer is not too thin or too thick. The crack of the part can be prevented. The semiconductor device having such a structure is also designed so that bolts are inserted through metal cylindrical collars at four corners of a mounting frame of an insulating resin case frame and tightened and fixed to an electronic device or the like. Since the base plate does not directly contact the resin portion of the case frame, the tightening force is not applied to the resin portion of the case frame, so that resin deformation can be prevented, and inadvertent warpage of the case frame can be eliminated. In the case where an escape reservoir groove for the adhesive is formed around the step surface of the opening, the excess resin that has protruded at the time of bonding can be escaped and accumulated, and appearance defects can be eliminated.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1A is a partial cross-sectional view showing a state before mounting a case frame and a heat radiation base plate in a semiconductor device according to an embodiment of the present invention, and FIG. FIG. 4 is a partial cross-sectional view showing a state after attachment to a heat dissipation base plate.

The semiconductor device of this embodiment is a semiconductor module called a power module or an intelligent power module, and has the same planar structure as shown in FIG. Similarly to the conventional example, the cross-sectional structure of the semiconductor module of this example is substantially the same as that of FIG. A radiating base plate (metal plate) 20 fixed to the step surface 14 with an adhesive to close the opening, and circuit boards (ceramic substrates) 30 and 31 fixed to the inner surface of the radiating base plate 20 with solder or the like. This circuit board 30
A lead frame 40 to 45 in which the inner lead tips A are connected to the upper thick film wiring, a gel-like resin (silicone resin) sealing material 50 for immersing the inner leads of the circuit boards 30, 31 and the lead frames 40 to 45; A cover plate 60 made of insulating resin is fixed to the stepped surface 18 on the other surface side of the case frame 10 with an adhesive to close the opening.

At four corners of the case frame 10, there are formed mounting seat portions 15 which are thin portions of resin, into which metal cylindrical collars 80 for the through holes 15a are embedded by integral molding (insert molding). I have. This metal cylindrical collar 8
0 is embedded so that the end face on the back surface side thereof protrudes beyond the level of the opening step surface 14 by a gap d (for example, 0.1 to 0.2 mm). A relief groove 85 for the adhesive 15c is formed around the step surface 14 of the opening.

The adhesive 1 is applied to the step surface 14 of the opening of the case frame 10.
After applying a predetermined amount of 5c with an automatic coating machine, a heat dissipation base plate 20 having a metal through-hole 20a is attached to fix the case frame 10 and the base plate 20 together. At this time, since the end surface of the metal cylindrical collar 80 protrudes from the level of the opening step surface 14 by the gap d, as shown in FIG.
An adhesive layer having a thickness corresponding to the gap d is secured. For this reason, the thickness variation of the adhesive 15c can be eliminated. It is possible to prevent peeling of the adhesive layer, leakage of the gel resin sealing material, and cracking of the mounting seat.

In mounting the semiconductor module of this embodiment, through-hole bolts (not shown) are inserted into the through-holes 15a of the metal cylindrical collar 80 and the through-holes 20a of the base plate 20, and tightened and fixed. However, since the protruding portion of the metal cylindrical collar 80 serves as a stopper as a base plate receiving portion, the metal base plate 20 does not directly contact the resin portion of the case frame 10, so that the tightening force is reduced. Resin deformation can be prevented irrespective of the resin portion of the frame 10, and unintentional warpage of the case frame can be eliminated.

Furthermore, in the present embodiment, the escape reservoir groove 8
5, the excess resin that has protruded from the gap is released when the adhesive is applied.
And is not exposed on the surface of the base plate 20, so that the appearance defect can be eliminated.

[0016]

As described above, according to the present invention, the metal cylindrical collar for the through hole in the mounting seat at the four corners of the case frame is provided with a predetermined end face whose level is determined from the level of the stepped surface to which the adhesive is applied. Protrudes by the length of the metal cylinder
The end face of the
Adhesion to the gap formed between the difference surface and the heat dissipation base plate
It is characterized by the presence of an agent . Therefore, the following effects are obtained.

Since the adhesive layer having a thickness corresponding to the gap is secured and its variation can be eliminated, peeling of the adhesive layer, leakage of the gel resin sealing material, and cracking of the mounting seat can be prevented. .

Since the protruding portion of the metal cylindrical collar serves as a stopper and the metal base plate does not directly contact the resin portion of the case frame, the tightening force is not applied to the resin portion of the case frame, thereby preventing the resin deformation and unexpectedly It is possible to eliminate the warp of the case frame.

[0019]

[Brief description of the drawings]

FIG. 1A is a partial cross-sectional view showing a state before attachment of a case frame and a heat radiation base plate in a semiconductor device according to an embodiment of the present invention, and FIG. 1B is a case frame and heat radiation base plate in the semiconductor device. It is a fragmentary sectional view showing the state after attachment.

FIG. 2 is a plan view illustrating a structure of a semiconductor device called a power module.

FIG. 3 is a cross-sectional view showing a state cut along a line QQ ′ in FIG. 2;

FIG. 4 is a partial cross-sectional view showing a mounting structure of a case frame and a heat radiation base plate in a conventional semiconductor device called a power module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Insulating resin case frame 12 ... Frame part 14, 18 ... Opening step surface 15 ... Mounting seat part 15a, 20a ... Through hole 15c ... Adhesive 20 ... Metal heat dissipation base plate 30, 31 ... Circuit boards 32, 34 ... Semiconductor elements (chips) 32a, 34a Bonding wires 40 to 45 Lead frames 40a to 40a Terminal seat plates 50 Gel-like resin sealing material (silicone resin) 60 Insulating lid plates A, B ... Inner lead tips P1 P16: Lead pin 70: Lead pin block 80: Metallic tubular collar 85: Relief storage groove

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-81461 (JP, A) JP-A-59-86249 (JP, A) JP-A-60-88446 (JP, A) 177295 (JP, A) JP-A 2-108377 (JP, U) JP-A 56-81546 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 23/28-23 / 31

Claims (2)

(57) [Claims] 1. A case frame made of an insulating resin having a lead frame extending from a frame portion, a metal heat dissipation base plate fixed to one of the step surfaces of the case frame with an adhesive and closed. A circuit board on which a semiconductor element mounted on the inner surface of the heat radiation base plate and connected to the tip of the inner lead of the lead frame is mounted; and a gel filling the inner space of the case frame and immersing the circuit board and the inner lead. Resin sealing material, a cover plate made of an insulating resin for closing the other opening of the case frame, and a metal cylindrical collar for a through hole embedded in the mounting seats at the four corners of the case frame by integral molding. Wherein the end face of the metal cylindrical collar projects from the level of the stepped surface to which the adhesive is applied by a predetermined length, and the protruding metal cylindrical collar
The end face of the
A groove formed between the opening step surface and the heat dissipation base plate.
A semiconductor device , wherein the adhesive is interposed in a gap . 2. The semiconductor device according to claim 1, wherein
The semiconductor device , wherein the gap is 0.1 to 0.2 mm .