Z-axis conductive adhesive for TAB and fine pitch interconnects

Solder are used extensively in both die-attach and component attach in the first and second levels of electronic packaging. With the commercialization of VLSI and ULSI devices, both levels of fabrication have encountered difficulties in both manufacturability and reliability. These problems are analyzed and a novel solution of Z-axis, `stress-free´, and thermally conductive adhesives are introduced. The adhesive system has been engineered to simulate all the desirable characteristics of soldering such as fast `curing´ speed (milliseconds), ambient storage, low thermal and low electrical contact resistances, and reworkability. The drawbacks of solders, such as fatigue failures, stress-induced failures, and bridging, are avoided. All of these basic properties and some of the applications are discussed