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Extraction of Chloride in Epoxy Circuit Package

IP.com Disclosure Number: IPCOM000083581D
Original Publication Date: 1975-Jun-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

DiGiacomo, G: AUTHOR

Abstract

In some circuit modules, a semiconductor chip has an epoxy package. These packages may contain chlorides that are leachable by water that enters the package. The water carries the chlorides to the conductors of the module and cause the conductors to corrode and fail. Packages can be tested to determine the amount of leachable chloride, and the failure rate of the circuit modules can be predicted from the test results.

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Extraction of Chloride in Epoxy Circuit Package

In some circuit modules, a semiconductor chip has an epoxy package. These packages may contain chlorides that are leachable by water that enters the package. The water carries the chlorides to the conductors of the module and cause the conductors to corrode and fail. Packages can be tested to determine the amount of leachable chloride, and the failure rate of the circuit modules can be predicted from the test results.

The package is abraded parallel to the chip to expose the chip and the metal conductor frames, and the frames and the chip are removed. The remainder of the package is cut into two parts. The two parts are given a coating of graphite which makes them conductive, so that they do not accumulate a charge during a subsequent microprobe operation.

One of the parts is then exposed to boiling water vapors for 25 hours. This time and vapor concentration are sufficient to remove all the leachable chlorides, without regard to the actual concentration of chlorides and the diffusion coefficient of water. In the normal operation of a circuit module these factors rate in an actual situation and thereby establish the rate at which chlorides are leached, and they thereby establish the rate at which modules fail from leachable chlorides. The part that has been exposed to water vapor is then dried in a desiccator or in air.

The two parts are then rejoined so that a test for chlorides can be made on two regions that are...