Anisotropic conductive paste available for flip chip

This report aims to explain the applications, concepts, and properties of ACP (anisotropic conductive paste), which was developed for flip chip joining. ACP is a nonsolvent, one-pack-type of liquid connection material. It is composed structurally of fine conductive particles diffused in liquid thermosetting resin. With this paste thermally crimped between two electrodes to provide physical bonding, electrodes that are located opposing or adjacent to each other are provided with conductivity or insulation, respectively. ACP is outstanding in terms of hardening time, requiring only a few seconds at 200°C or above, thus assuring high industrial productivity. Also, it is highly stable in long-term storage extending over a few months. Furthermore, the paste´s conductivity and insulation properties mean that it can successfully provide flip chip connection with assured reliability. Mounting does not involve the use of lead or flux, and thus the paste is environmentally friendly. ACP is easy to handle and outstanding in terms of productivity, and can thus be recommended as a mounting method with a wide scope for application