JPH07202088A - Semiconductor device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a highly reliable semiconductor device capable of safely protecting a mechanically fragile insulating substrate on which a semiconductor chip is mounted from stress applied to a metal base plate which also serves as a heat sink. To do. [Structure] The insulating substrate 2 on which the semiconductor chip 1 is mounted is
It is mounted on the metal base plate 3 that also functions as a heat sink and soldered,
In the semiconductor device assembled by combining the resin case 4 and the external lead-out terminal 5 with this, concave grooves 10 and 11 for absorbing stress are formed in a portion outside the soldering region of the insulating substrate with respect to the metal base plate. Then, the stress applied from the outside to the metal base plate is concentrated and absorbed in the groove portion, and the insulating substrate is safely protected from cracks and substrate breakage due to the stress.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a power transistor,
The present invention relates to a semiconductor device for a diode, a thyristor module or the like.

[0002]

2. Description of the Related Art First, a conventional assembly structure of a semiconductor device to which the present invention is applied is shown in FIGS. In the figure, 1 is a semiconductor chip, 2 is an insulating substrate on which the semiconductor chip 1 is mounted (made of ceramic or aluminum nitride, and a circuit pattern is formed on the surface thereof),
3 is a metal base plate that also serves as a heat sink, 4 is a resin case, and 5 is a resin case.
Is an external lead terminal, 6 is a gel filler (silicone gel), 7 is a sealing resin (epoxy resin), and the insulating substrate 2 is mounted on a metal base plate 3 and joined by solder 8. . It should be noted that bolt holes 9 for attaching the semiconductor device to heat radiation fins, equipment, etc. are opened at the four corners of the metal base plate 3.

[0003]

By the way, the above-described conventional semiconductor device has the following problems. That is, the insulating substrate 2 made of ceramic, aluminum nitride or the like has a mechanically brittle property, and when stress such as bending is applied from the outside, cracks and substrate breakage easily occur, and the insulating substrate 2 functions as an insulating substrate. Disappear.

On the other hand, the metal base plate 3 on which the insulating substrate 2 is mounted and soldered is usually a copper flat plate having a thickness of about several mm. For this reason, when mounting the metal base plate 3 on the block of the heat radiation fins, equipment of the destination, etc., by inserting bolts through the bolt holes 9 and the surface of the mating mounting member is uneven, the flatness is low. When the bolts are tightened, bending stress is applied to the metal base plate itself to cause warping, and this stress may spread to the insulating substrate 2 to cause cracks or substrate breakage.

The present invention has been made in view of the above points, and an object thereof is to solve the above problems and to provide a highly reliable semiconductor device capable of safely protecting an insulating substrate from a stress applied to a metal base plate. To provide.

[0006]

According to the present invention, the above object is achieved by forming a groove for absorbing stress on a metal base plate at a position outside the soldering region of the insulating substrate. Further, the concave groove in the above configuration can be specifically implemented in the following modes.

(1) A groove is formed at an intermediate position between a plurality of insulating substrates mounted side by side on a metal base plate. (2) The concave groove is formed in the peripheral area of the mounting bolt hole drilled in the metal base plate. (3) The groove depth of the concave groove is 30 to 70 of the plate thickness of the metal base plate.
Set in the range of%. (4) The concave groove is filled with an elastic caulking material.

[0008]

According to the above construction, the thickness of the remaining portion of the recessed groove forming portion of the metal base plate is locally smaller than that of the other portion, and is easily deformed. Therefore, when bending stress is applied to the metal base plate due to bolt fastening or the like, most of the stress concentrates in the recessed groove portion formed in the metal base plate, and deformation (bending) occurs in this recessed groove portion to reduce the stress. Absorb.
As a result, no deformation occurs in the mounting area of the thick insulating substrate, and the mechanically fragile insulating substrate is safely protected from cracks and substrate breakage due to stress. The groove may be a slit-shaped continuous groove or a discontinuous groove formed by arranging depressions in a dotted line.

Further, in order to prevent the stress applied to the metal base plate from spreading to the mounting area of the insulating substrate, it is concave for a plurality of insulating substrates mounted side by side on one metal base plate. It is effective to form the groove between the insulating substrate and the insulating substrate and also form the concave groove in the peripheral region of the mounting bolt hole. Further, if the groove depth of the concave groove is too large, the remaining margin of the plate is thinned accordingly, and the mechanical strength of the metal base plate itself is lowered, so that unnecessary deformation is likely to occur during manufacture and assembly. Further, if the groove depth is too shallow, almost no stress absorption effect can be obtained. From this viewpoint, by practically setting the groove depth of the concave groove within the range of 30 to 70% of the plate thickness of the metal base plate,
The stress absorption effect can be effectively obtained while ensuring the required strength.

In addition, by filling the concave groove with an elastic caulking material such as silicon resin, the metal base plate itself can be protected in handling without impairing the stress absorbing effect.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings of the embodiment, the same members corresponding to those in FIGS. 4 and 5 are designated by the same reference numerals and the description thereof will be omitted. First, in the embodiment shown in FIGS. 1 and 2, in comparison with FIG. Around the drilled mounting bolt hole 9, linear and circular slit-shaped concave grooves 10 and 11 are dispersed and newly formed. Here, the thickness of the metal base plate 3 is set to 3 mm, and the concave groove 10,
The groove depth of 11 is set to 1.5 mm, which is 1/2 of the plate thickness. Further, the concave grooves 10 and 11 are filled with an elastic caulking material 12 such as silicon resin.

With such a structure, even when bending stress is applied to the metal base plate 3 by fastening bolts through the bolt holes 9 of the metal base plate 3 to the mounting members (radiation fins, devices) on the other side, and the like. Most of the stress is the groove 1
Concentrate on the 0 and 11 parts and transform (bend) into this groove
Occurs and absorbs the stress. Therefore, stress does not spread to the mounting region of the thick insulating substrate 2 to cause warping and bending deformation, and the insulating substrate 2 is mechanically fragile.
Can be safely protected from cracks and substrate cracks caused by stress. Even if only one of the grooves 10 and 11 is provided, the stress absorbing effect is somewhat reduced, but the stress that spreads to the insulating substrate 2 can be reduced.

FIG. 3 shows an applied embodiment of the present invention, in which recesses 13 are intermittently formed on the metal base plate 2 along a portion corresponding to the slit-shaped groove 10 in the embodiment of FIG. They are formed to form discontinuous concave grooves.
It has been confirmed from the experimental results that the stress absorption effect almost equal to that in FIG. 2 can be obtained also in this embodiment.

[0014]

As described above, according to the structure of the present invention, as compared with the metal base plate which also serves as the heat dissipation plate of the semiconductor device,
Insulation board mounted with semiconductor chips (ceramic,
By forming a groove for absorbing stress in a place outside the mounting area of (made of aluminum nitride), even if bending stress is applied to the metal base plate due to fastening of mounting bolts, this stress is concentrated in the groove However, it is possible to safely protect the insulating substrate, which is mechanically brittle by absorption by the deformation of the concave groove portion, from cracks caused by stress, and thus the reliability of the semiconductor device can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing the configuration of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a plan view of the metal base plate in FIG.

FIG. 3 is a plan view of a metal base plate according to an application example of the present invention.

FIG. 4 is a sectional view showing the configuration of a conventional semiconductor device.

FIG. 5 is a plan view of the metal base plate in FIG.

[Explanation of symbols]

 1 Semiconductor Chip 2 Insulating Substrate 3 Metal Base Plate 4 Resin Case 5 External Lead-out Terminal 8 Solder 9 Mounting Bolt Holes 10, 11 Slit-like Grooves 12 Caulking Material 13 Dimples (Discontinuous Grooves)

Claims (5)

[Claims] 1. An insulating substrate on which a semiconductor chip is mounted,
It is mounted on a metal base plate that also serves as a heat sink and soldered,
In a semiconductor device constructed by assembling a resin case and an external lead terminal in combination with this, a groove for stress absorption is formed at a position outside the soldering region of the insulating substrate with respect to the metal base plate. Semiconductor device. 2. The semiconductor device according to claim 1, wherein the groove is formed at an intermediate position between a plurality of insulating substrates mounted side by side on the metal base plate. 3. The semiconductor device according to claim 1, wherein the recessed groove is formed in a peripheral region of a mounting bolt hole formed in the metal base plate. 4. The groove depth of the concave groove is set to 30 of the thickness of the metal base plate.
4. The semiconductor device according to claim 1, wherein the semiconductor device is set in a range of 70% to 70%. 5. The semiconductor device according to claim 1, wherein the concave groove is filled with an elastic caulking material.