Electricity: conductors and insulators – Feedthrough or bushing – Compression
Patent
1979-07-12
1982-07-20
James, Andrew J.
Electricity: conductors and insulators
Feedthrough or bushing
Compression
357 81, 357 80, 174 52R, H01L 2302, H01L 2312, H01L 3902
Patent
active
043409024
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a semiconductor device and more particularly to a semiconductor device with an improved heat radiating ability.
2. Background Art
Recently, integration of a semiconductor device and an electric-circuit device packaged therewith have been improved a great deal. As a result, power consumption per unit area of the semiconductor has greatly increased. A high power semiconductor device generates much heat. Accordingly, sufficient heat radiating from a semiconductor chip, i.e. sufficient cooling of the semiconductor device, becomes a requisite condition to improve the semiconductor device and the electric-circuit device.
FIG. 1 of the drawings illustrates a first example of the prior art (U.S. Pat. No. 3,872,583). In FIG. 1 a semiconductor device such as a package for a large scale integrated circuit (LS1) chip is illustrated.
The device illustrated in FIG. 1 comprises a ceramic base 11, a semiconductor chip 12, a metalized lead pattern 13, external connecting terminals 14, a ceramic frame 15, a cover 16, a cylindrical cooling stud 17 and cooling fin assembly 18. The semiconductor chip 12 is received within a central recess provided on one of the major surfaces of the ceramic base 11, and is secured onto said ceramic base by way of soldering. The lead wires extended from wire bonding pads of the semiconductor chip 12 are bonded to the inner extremities of the metalized lead pattern 13 and then the outer extremities of the pattern 13 are connected to the external connecting terminals 14. The cover 16 is secured on the ceramic frame 15 so as to hermetically enclose the semiconductor chip 12 within the recess. The cooling stud 17 is secured to a metalized layer provided on the other major surface of the ceramic base 11 and, then, the cooling fin assembly 18 is press-fitted around the stud 17 so as to be firmly fixed thereon.
In the semiconductor device having the package structure, described above, which is incorporated with the semiconductor chip, heat generated in the semiconductor chip 12 during operation, is transferred to the stud 17 and to the fin assembly 18 via the ceramic base 11. However, since the thermal conductivity of ceramic is rather low, sufficient cooling through the ceramic base 11 can not be expected. On the other hand, the semiconductor chip 12 and the ceramic base 11 or the ceramic base 11 and the cooling stud 17 are strongly secured to each other. Accordingly, when thermal stresses are caused in the ceramic base 11, based on the difference in the thermal expansion coefficients of the ceramic base 11 and the radiating stud 17, the ceramic base 11 together with the semiconductor chip 12 are apt to be cracked. Also, in a case where the fin assembly 18 is designed to be firmly secured on the stud 17 by press-fitting alone, a required accuracy in press-fitting between the inside diameter of the fin assembly 18 and the outside diameter of the stud 17 must be on the order of 1/100 mm. When the fin assembly 18 is press-fitted with such high-accuracy on the stud 17, a large mechanical pressure will be applied to the ceramic base 11 and the external connecting terminals 14, and will often cause the ceramic base to be destroyed and the terminals to be deformed.
In order to eliminate the above described drawbacks, the applicant of the present invention has provided the following described semiconductor device. FIG. 2 of the drawings illustrates a second example of the prior art (Japanese Laid open Patent Application No. 50-139,674). In FIG. 2, a semiconductor device, which has a semiconductor chip in a through hole provided substantially in a central portion of a ceramic base, comprises a beryllia plate which covers one side of the through hole and which is secured to one of the major surfaces of the ceramic base; the semiconductor chip being secured through an oxygen-free copper plate and a molybdenum plate to the bottom of the recess formed by one side of the beryllia plate and the through hole of the ceramic base; a cooling stud being se
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Honda Norio
Sugahara Takehisa
Fujitsu Limited
James Andrew J.
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