Solder and conductive adhesives served as interconnections since the 1920’s. Few situations allowed for the exchange of one with the other. With the Industry moving away from lead, metallurgical alternatives surfaced. Several systems successfully replace solder in applications including cell phones and hand-held electronics. Although the United States has been slow to respond, conversion is inevitable, including high reliability applications.

Alternatives must prove reliable to be acceptable. Alternatives include nonlead solders or conductive adhesives; neither are direct drop-ins. Metallurgical substitutes re-flow at higher temperatures causing component / processing concerns. Data indicate several may offer improved reliability; the aforementioned concerns remain. For some applications, adhesive technology may provide higher reliability.

Newer polymers are demonstrating improvements over previous adhesives. Nano-metals with unique morphology can exhibit electrical conductivities greater than traditional polymer technology. Advances in low glass transition technologies have improved the performance of adhesives allowing for successful applications in high stress environments. This paper describes an application.

This article originally appeared in Global SMT & Packaging magazine 6.6 - June/July 2006.

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Keywords : Frank Liotine, Jr., Conductive adhesive, lead-free solder, medical, military, space electronics, hybrid polyurethane, nano-metal, nanotechnology

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