Evaluation of the Reliability of Film Adhesives Under Hygrothermal Condition

Mechanical evaluation method of adhesive strength for bonding IC chips in chip-stacked packages is investigated. These film adhesives are required to bond IC chips securely under JEDEC moisture/reflow test. The stress condition of film adhesives under the moisture/reflow test is analyzed by FEM to clarify proper stress condition for the adhesive test. Thermal strain, moisture expansion and strain induced by vapor pressure is considered. It is found that the shear stress is the main loading factor on reflow process in the analysis. A shear test using chevron-shaped chip is proposed as the adhesive test, which apply shear load to the film adhesive at the corner of a chip. The specimen is fabricated by the same process of actual semiconductor manufacturing. The evaluation method is conducted without any problem. The proposed method is thought to be suitable for film adhesives of chip bonding.