Browse Prior Art Database

Semiconductor Module With Improved Air Cooling

IP.com Disclosure Number: IPCOM000086734D
Original Publication Date: 1976-Oct-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Cain, OJ: AUTHOR [+2]

Abstract

The drawing shows a ceramic wafer 2 having pins 3. A silicon chip 4 is connected to conductors (not shown) on wafer 2 by means of solder balls 5. A metal cap 6, shown in sections, is brazed to a base 8 of nickel plated molybdenum that is formed on wafer 2. These components of the module are conventional. For cooling chip 4, heat is transferred through solder balls 5 to wafer 2 or through the air space to cap 6.

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Semiconductor Module With Improved Air Cooling

The drawing shows a ceramic wafer 2 having pins 3. A silicon chip 4 is connected to conductors (not shown) on wafer 2 by means of solder balls 5. A metal cap 6, shown in sections, is brazed to a base 8 of nickel plated molybdenum that is formed on wafer 2. These components of the module are conventional. For cooling chip 4, heat is transferred through solder balls 5 to wafer 2 or through the air space to cap 6.

The module has a thin foil 9 of a metal such as silver and is connected between cap 6 and the upper surface of chip 4 (electrically the back side of the chip). This foil provides improved heat transfer from the chip to the metal cap.

Foil 9 is attached to cap 6 before the cap is brazed to wafer 2. A film 12 of solder is formed inside the cap and the silver foil is attached to the cap by heating the solder film. The backside of the chip is given a metal layer 14 to which the foil will bond after assembly.

Layer 14 can be formed by first evaporating a film of gold onto the chip and then heating the chip to 370 degrees C for a few seconds to cause the gold to react with the silicon and form a wettable gold-silicon alloy. Then a layer of tin, lead or indium is deposited on the gold layer. When the cap has been assembled, the module is heated for a few seconds to cause the foil to bond to the solder on the backside of the chip. This cooling apparatus and the assembly technique are useful for modules having a plural...