Browse Prior Art Database

Solder Transfer Technique

IP.com Disclosure Number: IPCOM000082780D
Original Publication Date: 1975-Feb-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Noth, RW: AUTHOR [+2]

Abstract

Described is a technique for salvaging integrated circuit chips removed from defective substrates.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 93% of the total text.

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Solder Transfer Technique

Described is a technique for salvaging integrated circuit chips removed from defective substrates.

When good integrated circuit chips are removed from defective substrates, the solder pads on the chips become reduced in volume to between 10 and 20 mils /3/. A solder volume of at least 40 mils /3/ but less than 90 mils /3/ is required for suitable bonding.

Replacement of such solder volumes on such chips has been virtually impossible, because of the size of the chip and the difficulty of aligning the evaporation masks on the individual chips.

This technique teaches that small solder volume replacement solder pads 40 to 45 mils /3/ can be vacuum deposited on a backing material in any desired patterns or amount by using the usual vacuum evaporation techniques and masks, and that these replacement solder pads can be transferred from the backing material to individual chips, by aligning the chips with the evaporated solder pads and heating them.

It is necessary that the pattern replacement solder pads be deposited on the backing material as a mirror image of the pattern on the chip, and that the backing material be such that the evaporated material will adhere to it by mechanical action, yet will be released when heated to molten solder temperatures.

Polyimides such as KAPTON* have been found to be a suitable backing material. Such polyimides have a further advantage in that they are transparent, thus permitting fast, accurate alignment of th...