Carbon Nanotube Filled Conductive Adhesives

Conductive adhesives have been used in electronics packaging for many years for their low temperature lead-free processing capability, simple processing and thereby low cost. One fact hindering the replacement of traditional solder paste by conductive adhesives is that high loading of filler decreases the impact strength, while decreasing filler loading results in poor electrical properties. Carbon Nanotubes (CNTs), a new material based on CM Fullerenes (Bucky Balls) and graphite rolls have many interesting properties. One of the properties is the electrical conductivity, which we employed in the development of new lightweight, electrically conductive adhesives. Nanotubes have the potential to produce high conductivity materials at very low weight percent loadings while still maintaining the desirable mechanical properties of the polymer matrix. In this paper, new conductive adhesives were formulated by adding the multiwall nanotubes (MWNT) as filler to a two-part epoxy. Different loadings of CNTs and mixing methods were used to make the new conductive adhesives. SMT assembly processes were performed using the new CNTs filled conductive adhesive to prepare the test pattern. The properties were tested and compared with traditional solder bump (Sn/Pb 63/37).