IE52449B1

IE52449B1 - A semiconductor integrated circuit device with an improved heat sink

Info

Publication number: IE52449B1
Application number: IE1626/86A
Authority: IE
Original assignee: Fujitsu Ltd
Priority date: 1980-02-29
Filing date: 1981-02-26
Publication date: 1987-11-11

Description

The present invention relates to a semiconductor device, and more particularly to a semiconductor device which has a plurality of IC (Integrated Circuit) packages mounted on a mother board. to example of a known semiconductor device with four IC packages mounted on a mother board is described in Proceedings of the Technical Program, National Electronic Packaging and Production Conference, Ceramic Chip Carrier - The New Standard In Packaging by M. L. Burch and Β. M. Hargis, Minnesota Mining and Manufacturing Company, 1977. This publication describes an arrangement in which the IC packages or chips are mounted in a row, using bonding pads to connect chip carrier assemblies to a ceramic substrate.

The IBM Technical Disclosure Bulletin, Vol. 22, No. 6 November 1979, pages 2294 - 2296, discloses a matrix of heat sinks overlying corresponding chips and embedded in a cap sealed to a substrate to which the chips are also connected.

Heat sinks for isolated semiconductor chips are also known (for example a cylindrical stand with a cooling fin assembly, as diclosed in U.S. Patent No. 3872683).

According to the present invention, there is provided a semiconductor device comprising: a mother board; a plurality of semiconductor elements each having a plurality of bonding pads, the semiconductor elements being mounted in a matrix on the mother board; a plurality of pin terminals extending from the mother board, the mother board having electrical interconnections to make connection to the pin terminals; and a plurality of heat sinks mounted on the respective semiconductor elements, each heat sink comprising a heat-conducting shaft arranged perpendicularly to the semiconductor elements and provided with heat-dissipating fins; each semiconductor element being an IC package and forming part of a separate IC package unit which also 52448 - 3 comprises the respective heat sink, in which the heatdissipating fins are in planes perpendicular to the axis of the shaft of the heat sink, and a base board the area of which is substantially greater than the crosssectional area of the shaft of the heat sink and which is also in a plane perpendicular to the axis of the shaft, the IC package units being independently mounted on the mother board and the mother board comprising a multi-layer circuit through which the IC packages are connected to the pin terminals.

In order that the invention may be better understood, the invention will now be described with reference to the accompanying drawing which is a perspective view illustrating a semiconductor device having a multi-package structure and a heat-sink structure according to a preferred embodiment of the invention.

As illustrated in the Figure, the present embodiment of the invention comprises a square-shaped mother board within which printed circuit patterns having a multilayer structure are formed. A plurality of pin terminals are attached to the four edges of the mother board 6 and each of the pin terminals 7 is electrically connected to the printed circuit within the mother board 6 appropriately. On the mother board 6, four IC packages are mounted. Each of the IC packages 2 contains a semiconductor element therein and has a'plurality of bonding pads at the base thereof which are electrically connected to the semiconductor element. Each of the bonding pads is bonded to a corresponding one of printed circuit patterns which are formed on the mother board 6 under the bonding pads and which are connected to the printed circuit patterns formed within the mother board 6. The semiconductor device according to the present embodiment further comprises four heat sinks 1 each of which adheres to a respective one of the four IC packages 2. The heat sinks 1 which are made 53449 - 4 of materials having high thermal conductivity such as aluminum comprise a cylindrical heat conducting shaft portion 11' arranged perpendicular to the base board portion at the centre thereof. A plurality of heat dissipating fins 3 are arranged around the heat conducting shaft portion 11' at a constant distance and in parallel with each other. Each of the heat dissipating fins 3, of which the lowest 3' constitutes the base board portion, is a thin board having approximately a round shape.

The base board (i.e. the lowest fin) of each heat sink 1 may be joined to its respective IC package 2 by means of an epoxy adhesive agent, or by means of brazing, between the base board portion and the top surface of the IC package.

When the above-mentioned semiconductor device is operated, each of the IC packages 2 generates heat due to the heat generation from the semiconductor element mounted within the IC package. The heat generated from each of the IC packages 2 is transferred from the top surfaces of the IC packages 2 through the base board portion of each heat sink 1 to each heat conducting shaft 11'. Since each heat conducting shaft 11' is made of materials having high thermal conductivity, the heat conducting shaft 11' is heated up so that the temperature distribution is approximately the same throughout the whole length of the heat conducting shaft 11'.

The heat delivered to the heat conducting shaft 11' is further transferred from the heat conducting shaft 11* to each of the heat dissipating fins 3 and dissipated into the surrounding air.

Claims

1. CLAIflS

1. A semiconductor device comprising: a mother board; a plurality of semiconductor elements each having a plurality of bonding pads, the semiconductor elements being mounted in a matrix on the mother board; a plurality of pin terminals extending from the mother board, the mother board having electrical interconnections to make connection to the pin terminals; and a plurality of heat sinks mounted on the respective semiconductor elements, each heat sink comprising a heat-conducting shaft arranged perpendicularly to the semiconductor elements and provided with heat- dissipating fins; each semiconductor element being an IC package and forming part of a separate IC package unit which also comprises the respective heat sink, in which the heatdissipating fins are in planes perpendicular to the axis of the shaft of the heat sink, and a base board the area of which is substantially greater than the cross-sectional area of the shaft of the heat sink and which is also in a plane perpendicular to the axis of the shaft, the IC package units being independently mounted on the mother board and the mother board comprising a multi-layer circuit through which the IC packages are connected to the pin terminals.

2. A semiconductor device according to Claim 1, including four IC packages and in which the mother board is substantially square in shape with the semiconductor devices mounted on the mother board each in a different quarter of the square, the pin terminals extending from the four sides of the mother board.

3. A semiconductor device according to Claim 1 or 2, wherein the heat sinks are joined to their respective IC packages by means of an epoxy adhesive agent.

4. A semiconductor device according to Claim 1 or 2, wherein the heat sinks are joined to their respective IC packages by a brazing operation between the base board portion and the top surfaoe of the IC package. - 6 5. A semiconductor device according to any preceding claim, wherein the heat-dissipating fins for the heat sinks are shaped as discs. 6. A semiconductor device according to Claim 1,

5. Substantially as hereinbefore described with particular reference to and as illustrated in the accompanying drawing.