High temperature NCP bonding process for COF package

초록

COF(Chip-on-Film) package for LDI(LCD drive IC) module has been manufactured by underfill process following Au-to-Sn thermocompression bonding. As the interconnection pitch becomes finer below 25 ㎛, a new process, such as NCP(NonConductive Paste) bonding, is required to replace capillary underfill process. In this study, NCP formulation and process variables for high temperature flip chip bonding were investigated to form the metallic bonding between bumps. NCPs were formulated with epoxy resin, hardener and catalyst according to the response surface method. The LDI chip for test package had a thickness of 470 ㎛, area of 11,772x924 ㎛and the smallest bump pitch of 25 ㎛. The snap cure behavior of NCPs were characterize by DSC (Differential Scanning Calorimetry) and DEA(Dielectric Analysis). The peel strength and void formation at the joint were measured and the various reliability tests, such as high temperature storage, thermal cycling and pressure cooker tests, were performed. The results showed that the high reliability of COF package could be achieved by the high temperature NCP bonding process.