Recent advances of interconnection technologies using anisotropic conductive films

Anisotropic conductive films(ACFs) consists of conducting particles and adhesive resins and have been widely used for packaging technologies in FPDs(Flat panel displays) such as LCDs(Liquid crystal displays) for last decades. So far various packaging technologies such as TCP(Tape carrier package) on LCD panel or PWB(Printed wiring board), COF(Chip on flex) on LCD panel or PWB and COG(Chip on Glass) using ACFs have been realized to meet the requirement of fine pitch capability and make the flat panel displays smaller, lighter and thinner. In order to meet the requirement of finer pitch interconnection of outer lead of TCP in LCD packaging technologies, the influence of conducting particles on contact resistance of ACF joints was investigated. It was found that the 50 micron pitch of outer lead interconnection of TCP is realized by optimizing the hardness of conducting particles. In addition, to meet fine pitch capability smaller than 50 micron pitch, the improvement of the adhesion characteristics against COF has been demonstrated in outer lead interconnection. It was confirmed that making conducting particles smaller is advantageous for the driver IC with small bump size and space in COG. Low temperature curable ACF using new curing system which cross-links at 140 degrees C in 10 sec bonding has been demonstrated in TCP/PWB interconnection.