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Piston-Like Structure With Electrically Isolating Plate Contacting Chip and Metal Structure Attached to Plate

IP.com Disclosure Number: IPCOM000034857D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Antonetti, VW: AUTHOR [+2]

Abstract

Some circuit modules have a thin, flat chip support, an array of chips on the upper surface of the support, and a cylindrical, thermally conductive member called a piston that releasably contacts the upper surface of the chip and conducts heat from the chip to a heat sink. The piston can be arranged to provide electrical isolation between the chip and the heat sink. Many piston-like structures have been proposed. This piston-like structure has a plate of beryllium oxide that contacts the chip and metal pins that are attached to the upper surface of the plate and extend to the heat sink. The plate can be larger than the chip. The plate is formed by a known process that provides a smooth lower surface for good contact with the chip. The upper surface is formed with shallow cylindrical cavities where the pins are to be located.

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Piston-Like Structure With Electrically Isolating Plate Contacting Chip and Metal Structure Attached to Plate

Some circuit modules have a thin, flat chip support, an array of chips on the upper surface of the support, and a cylindrical, thermally conductive member called a piston that releasably contacts the upper surface of the chip and conducts heat from the chip to a heat sink. The piston can be arranged to provide electrical isolation between the chip and the heat sink. Many piston-like structures have been proposed. This piston-like structure has a plate of beryllium oxide that contacts the chip and metal pins that are attached to the upper surface of the plate and extend to the heat sink. The plate can be larger than the chip. The plate is formed by a known process that provides a smooth lower surface for good contact with the chip. The upper surface is formed with shallow cylindrical cavities where the pins are to be located. A thin layer of tin is plated onto the upper surface of the beryllium oxide, covering the walls of the cavities as well. A low- temperature flowable alloy is placed in each hole, either as a preform or as a drop of melted alloy. The upper surface of the melted alloy is molded to a convex shape and the preform is given a convex upper surface. The metal pins are then positioned in the holes and the solder is reflowed to attach the pins to the plate. The convex upper surface of the alloy causes the reflow operation to proceed radially ou...