Embedded chip-in-flex (CIF) packages using wafer level package (WLP) with pre-applied anisotropic conductive films (ACFs)

For maximizing space efficiency and reducing process steps, embedded chip-in-flex (CIF) packages using wafer level package (WLP) with pre-applied anisotropic conductive films (ACFs) are one of the innovative packaging technology. This study was focused on the demonstration of CIF packages and their reliability evaluation. WLP was successfully performed in case of void-free ACF lamination on a 50 mum thin wafer, wafer dicing without ACF delamination, and flip-chip assembly which showed stable bump contact resistances. After flex-on-flex (FOF) assembly conditions were optimized, the CIF packages were successfully fabricated. The reliability of the packages such as high temperature/ humidity test (85degC/85% RH), high temperature storage test (HTST), thermal cycling test (T/C) was evaluated. As a summary, the CIF packages showed excellent 85degC/85% RH reliability.