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Browse Prior Art Database

Use of a Tinned Copper Slug For Module Reworking

IP.com Disclosure Number: IPCOM000048190D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Le Pape, B: AUTHOR

Abstract

Module rework implies the elimination of the solder pads which remain on a ceramic substrate after the removal of a semiconductor chip.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 100% of the total text.

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Use of a Tinned Copper Slug For Module Reworking

Module rework implies the elimination of the solder pads which remain on a ceramic substrate after the removal of a semiconductor chip.

The present method consists basically in the use of a porous copper slug which will absorb the molten solder when heated.

It includes the following steps:

1. Tinning a porous copper slug (approximately chip size)

with a low fusion point eutectic solder. It has been

demonstrated that a 63/37 lead tin solder composition

was optimal.

2. Applying the slug to the ceramic substrate at the chosen

chip site to be cleaned.

3. Heating the substrate in an oven in a nitrogen atmosphere

at a working

temperature in order to melt the solder. The latter

is almost totally absorbed by the porous slug (by

capillarity), leaving only a thin solder film with a

controlled height ( less than or equal to 5 microns)

at the solder pads sites.

4. Cooling the substrate. When the above mentioned solder

composition is used, there is no adherence between the

slug and the substrate.

The above method improves final rework yields, and is both low cost and highly reliable.

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