Novel Nano-Scale Conductive Films With Enhanced Electrical Performance and Reliability for High Performance Fine Pitch Interconnect

In this paper, a novel nano-scale conductive film which combines the advantages of both traditional anisotropic conductive adhesives/fllms (ACAs/ACFs) and nonconductive adhesives/fllms (NCAs/NCFs) is introduced for next generation high-performance ultra-fine pitch packaging applications. This novel interconnect film possesses the properties of electrical conduction along the z direction with relatively low bonding pressure (ACF-like) and the ultra-fine pitch (< 30 mum) capability (NCF-like). The nano-scale conductive film also allows a lower bonding pressure than NCF to achieve a much lower joint resistance (over two orders of magnitude lower than typical ACF joints) and higher current carrying capability. With low temperature sintering of nano-silver fillers, the joint resistance of the nano-scale conductive film was as low as 10^-5 Ohm. The reliability of the nano-scale conductive film after high temperature and humidity test (85degC/85% RH) was also improved compared to the NCF joints. The insertion loss of nano-scale conductive film joints up to 10 GHz was almost the same as that of the standard ACF or NCF joints, suggesting that the nano-scale conductive film is suitable for reliable high-frequency adhesive joints in microelectronics packaging.