Elsevier

Composites

Volume 22, Issue 3, May 1991, Pages 219-226
Composites

Resilient composite of silicone and foamed tin as a new material for electrical and thermal contacts

https://doi.org/10.1016/0010-4361(91)90322-8Get rights and content

Abstract

Silicone-infiltrated tin foam containing 14 volume % metal is a new composite material that is resilient up to a compressive stress of 2 MPa and a strain of 13%. Its volume electrical resistivity is 5 × 10−4ω cm and remains below 1 × 10−3ω cm up to 1700 compressive loading cycles (0.075 MPa). Its contact resistivity (with copper) decreases with pressure and levels off at 0.22 ω cm2 at a pressure of 0.07 MPa. Beyond 1000 compressive loading cycles (0.08 MPa), the contact resistivity rises, reaching 0.48 ω cm2 at 1700 cycles. The thermal expansion coefficient is 215 × 10−6°C−1 at 45°C, compared with a value of 282 × 10−6°C−1 for silicone. This composite is attractive as a material for electrical and thermal contacts in electronic packages. Compared with silicone-infiltrated tin foam, silicone-infiltrated tin-lead foam exhibits a lower volume electrical resistivity, a lower contact resistivity (with copper) and a higher fatigue resistance, but it is resilient only up to a compressive stress of 0.4 MPa and a strain of 0.8%. The bonding between silicone and tin is stronger than that between silicone and tin-lead.

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There are more references available in the full text version of this article.

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