Browse Prior Art Database

Chip Support Assembly

IP.com Disclosure Number: IPCOM000086404D
Original Publication Date: 1976-Sep-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 50K

Publishing Venue

IBM

Related People

Coombs, VD: AUTHOR [+2]

Abstract

This chip support assembly provides a means for elongating the ball-solder joints connecting the electrical contacts on a semiconductor chip to conductive lands on a substrate. It is desirable to elongate such joints so that they will be subject to a minimum of stress due to thermal expansion within the structure during usage.

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Chip Support Assembly

This chip support assembly provides a means for elongating the ball-solder joints connecting the electrical contacts on a semiconductor chip to conductive lands on a substrate. It is desirable to elongate such joints so that they will be subject to a minimum of stress due to thermal expansion within the structure during usage.

A pair of brackets 10 are attached to the chip 11 prior to chip positioning for reflow soldering. For the bracket-to-chip attachment, a solder with a melting point higher than any subsequent processing temperature is used in conjunction with a metallization coating on the back of the chip. The chip-bracket assembly is positioned on the substrate 12 and attached thereto by the ball-solder joints 13 (Fig. 3).

A substrate bracket 14 is positioned over the chip-bracket assembly and is soldered to the substrate. The substrate lands which act as solderable bases for the substrate bracket feet may be located where substrate circuitry necessitates. The metal chip and substrate brackets are sufficiently elastic in the X-Y direction that thermal expansion differences between the brackets and the chip and/or the substrate will not cause high stresses in the bracket solder joints.

If the ball-solder joints 13 (Fig. 4) were remelted, the chip lifted a distance "Z" (Fig. 3) and the chip brackets were caused to touch and be soldered to the substrate bracket, then a chip-substrate assembly will be produced, which assembly would have stretched the ball-solder joints 13 and would have the chip supported by the bracket-to-bracket structure.

One procedure for effecting chip joint remelting, chip lifting and bracket-to- bracket joining is shown in Figs. 1 and 2.

With the chip-bracket...