EPOXY PACKAGE FOR PRESSURE SENSOR

Publishing Venue

Motorola

Related People

Abstract

Low cost pressure sensor packages are typically molded from thermoplastic polymers and their thermal and mechanical limitations are of concern in certain applications. However, sensor packages molded from thermoset polymers significantly improve on these limitations.

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MOlOROLA INC. Technical Developments Volume 12 April 1991

EPOXY PACKAGE FOR PRESSUR$ SENSOR

by Victor J. Adams

   Low cost pressure sensor packages are typically molded from thermoplastic polymers and their thermal and mechanical limitations are of concern in certain applications. However, sensor packages molded from thermoset polymers significantly improve on these limitations.

   1. There is no seepage of air (3) into the package cavity along the leads (1) when an internal negative pressure (4) or vacuum is applied. Entrapped air (3) in the gel (6) distorts the sensor's electrical performance and often causes the gel (6) to erupt into the vent (7)

thereby attenuating the pr~essure signal altogether.

  2. The epoxy package (2) also provides excellent mechanical and dimensipnal stability over time and elevated temperatures, thereby avoiding parametric shifts that can occur with package distortions caused by external forces to the package.

  3. Thermoset epoxy ipackages have compatibility to a greater variety of midia than do the thermoplastic packages and do not conipromise adhesion properties when bonded to RTV's or other epoxies (9).

154 0 Motorola. 1°C. 1991