Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – With provision for cooling the housing or its contents
Patent
1996-09-12
1998-02-10
Saadat, Mahshid D.
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
With provision for cooling the housing or its contents
257706, 257707, 257727, 361719, 361720, H01L 2334, H01L 2310
Patent
active
057172480
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a cooling and screening device for integrated circuits, in particular for VLSI chips. A prior art device is known from EP-A-0 340 959.
Chips of this type contain large-scale integrated complex circuits such as, for example, complete processors. The electric power consumption of these circuits is so high that they cannot be operated without additional cooling measures. A further problem is to be seen in that said circuits are operated at very high clock frequencies, with the result that they emanate energetic electromagnetic interfering radiation which must be screened.
It is already known to fasten to the surface of the circuit housing a heat sink whose upper side is provided with cooling ribs or cooling pins. This heat sink must be connected to frame potential in order to achieve a screening effect. FIG. 5 shows an exploded perspective representation of a cooling and screening device, known from the prior art, for an integrated circuit 2 arranged on a printed circuit board 1. Contained therein is a heat sink 3 which has a metal plate 4 on whose upper side cuboid cooling projections 5 are arranged at a regular mutual spacing. The heat sink 3 is placed with its flat bottom side 6 onto the integrated circuit and covered by a frame 8 with the interposition of electrically nonconductive spacers. Cut-outs 9 in the frame 8 permit the cooling projections 5 to penetrate the latter.
The integrated circuit 2 is surrounded by a sheet-metal spring strip 10 which is provided on its bottom edge with soldering tips 11 arranged at a regular spacing. These tips are inserted into plated-through bores 12 in the printed circuit board 1 and soldered therein. Stamped out on the upper edge of the sheet-metal spring strip 10 are S-shaped contact springs 13 which in the assembled state of the arrangement embrace the edges 14 of the cover frame 8 and produce an electrical connection between said cover frame 8 and the printed circuit board. This arrangement on the printed circuit board is generally connected to frame potential. A similar arrangement, having a closed cover plate which serves exclusively for screening purposes, is also known from European reference EP-A-0 256 285. In both cases, the cover is held only by spring force. There is no gastight connection between this cover and the contact springs.
The cooling effect of the known arrangement represented in FIG. 5 is sufficient as long as the cover frame is not detached from the springs by vibrations. In addition screening problems also arise at times. These problems occur because although the frame 8 is reliably at frame potential, the cooling projections 5 project from the cover frame and emit interfering radiation because of their antenna effect (depending on the length of the cooling projections 5).
The known heat sink 3 is produced from a press-drawn section having ribs constructed in the longitudinal direction on the upper side. Transverse grooves are milled into the ribs in order to achieve cuboid cooling projections. This necessitates an additional work operation when producing the heat sink.
SUMMARY OF THE INVENTION
It is the object of the invention to specify a cooling and screening device for integrated circuits which exhibits an improved cooling and screening behavior and has fewer parts.
This object is achieved by means of the features cited in claim 1. The heat sink is penetrated near its side edges by cut-outs which extend from its bottom side to its top side. Contact pins are inserted into these with one of their ends such that they form a reliable, permanent electrical contact with the heat sink. In this arrangement, they project perpendicularly from the bottom side of the heat sink and can therefore be inserted like a multi-contact electric component into plated-through bores the printed circuit board and be soldered in these bores. This produces not only a reliable electrical connection, but also a mechanical connection, with the result that the heat sink cannot become detached from the integrated ci
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Patent Abstracts of Japan, vol. 018, No. 643, (E-1640), 7 Dec. 1994, JP-06-252282, 09 Sep. 1994, S. Hidetoshi, Shield Structure of Package, pp. 1-6.
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John Hans-Jorg
Neumann Gerd
Weege Horst
Arroyo T. M.
Saadat Mahshid D.
Siemens Nixdorf Informationssysteme AG
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