The Conductivities of Electrically Conductive Adhesives Containing Silver-Coated Graphite Particles By Self-Activated Deposition

Polymer-based conductive-adhesive materials have become extensively utilized in many applications including electronic packaging interconnects. Electrically conductive adhesives (ECAs) have acquired prestige as a potential replacement for solder interconnects. They not only provide a ‘lead-free’, ‘no clean’ alternative to solder; these highly compatible materials also offer viable answers to problems where solder is totally deficient. Other advantages such as lowered process temperature, increased metallization options, reduced thickness, decreased cost and equipment needs. The ECAs principally comprise an organic/polymeric binder matrices and conductive fillers. The conductive fillers furnish the ECAs with excellently electrical properties and the polymeric matrices provide the mechanical and physical properties. Meanwhile, it is very important to select the suitable materials for conductive particles. Nickel (Ni), copper (Cu), gold (Au), and silver (Ag) are by far commonly used conductive fillers for electrically conductive adhesives, and silver is totally unique among the affordable metals for its high conductivity of the oxide after exposure to heat and humidity. Besides, silver particles are easy to form and to fabricate into ideal shapes. This means that accurately the right sizes of particles can be produced for use as is, or for milling into fine flakes. However, from the aspect of its high prices, silver content may be lowered down for its applications in conductive adhesives. To overcome this, many improved methods are adopted. Metallization of graphite surface is one way deemed to be an effective approach to endow graphite with excellent metallic thermal and electrical conductivity and reduces the silver content of conductive fillers. Up to now, many methods have been adopted for surface metallization of materials, including electrophoretic deposition [1], electrodeposition [2], and chemical vapor deposition [3]. These techniques require either special equipment or complicated process control. Electroless deposition [4, 5] provides a highly effective but simple and advantageous method for industrial production, such as low-cost, uniform thickness, and low coating rate, etc [6].