In this study, the thermal and hygro-thermal behaviors of flip chip (FC) packages with a non-conductive paste (NCP) were evaluated under thermal shock (TS) and temperature-humidity (TH) tests. The main failure mode in TS and TH tests was a delamination between the bump and pad in the package. The electrical resistance of the package in the TH test was higher than in the TS test, indicating that the hygro-thermal expansion of NCP was larger than its thermal expansion. It was concluded that the stresses in the package were due to thermal and hygroscopic swellings during TS and TH tests, respectively. (C) Koninklijke Brill NV, Leiden, 2008