Motorola Corporation

Robert M Foss

Gerald R Severson

James R Hooker

A method for encapsulating electronic components in high acceleration and high thermal cycling environments. A liquid uncured thermal setting polyurethane formulation is mixed with a finely ground particulate foam which serves as a nucleating agent. The mixture is in accordance with the polyurethane formulation. The resultant foam contains open air pockets which allow it to be compressed and then re-expand.

Method of producing polyurethane foams for low stress encapsulation

Electronic packages and the like, particularly finished packages with leaky welds, are hermetically sealed by vapor deposition of a polymer film through a sealable port. A high quality film is obtained by slow deposition of a monomer vapor which subsequently polymerizes. The process is not destructive due to the lack of high temperatures and curing agents. Extremely low permeability for common molecules and for water vapor is achieved by utilizing C-type para-xylylene as the polymer material.

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Scottsdale, AZ, United States of America

Robert M Foss