Electrical conductivity of rigid polyurethane foam at high temperature

Technical Report · Sun Aug 01 00:00:00 EDT 1982

OSTI ID:5106136

Johnson, Jr, R T

The electrical conductivity of rigid polyurethane foam, used for electronic encapsulation, has been measured during thermal decomposition to 340/sup 0/C. The conductivity below approx. 150/sup 0/C is < 10/sup -13/ (ohm-cm)/sup -1/ but increases dramatically to approx. 10/sup -9/ (ohm-cm)/sup -1/ as the temperature is increased to 260 to 270/sup 0/C. At higher temperatures the conductance continues to increase, but some of this increase is due to sample softening and changes in sample geometry. With pressure-loaded electrical leads, sample softening results in eventual contact between electrodes (at approx. 340/sup 0/C) producing electrical shorting. Experiments in air and nitrogen environments showed no significant dependence of the conductivity on the atmosphere over the temperature range examined. The insulating characteristics of polyurethane foam below approx. 270/sup 0/C are similar to those for silicone-based (glass-fabric reinforcing) materials used for electronic case (or support structure) housings and are better than those for phenolics (glass-fabric reinforced). At higher temperatures (greater than or equal to 270/sup 0/C) the phenolics appear to be better insulators (combined physical and electrical characteristics) to approx. 500/sup 0/C and the silicones to approx. 600/sup 0/C. The Sylgard 184/GMB encapsulant is a significantly better insulator at high temperature than the rigid polyurethane foam.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5106136
• Report Number(s): SAND-82-1259; ON: DE82020468
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
POLYURETHANES
ELECTRIC CONDUCTIVITY
PERFORMANCE TESTING
TEMPERATURE DEPENDENCE
ELECTRICAL PROPERTIES
MATERIALS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PHYSICAL PROPERTIES
PLASTICS
POLYAMIDES
POLYMERS
SYNTHETIC MATERIALS
TESTING
360403* - Materials- Polymers &amp; Plastics- Mechanical Properties- (-1987)