Abstract
The criteria of reliability, mechanical property and aging lifetime in adhesiveless copper/polyimide (Cu/PI) can be identified and described by distinct environmental stress testing, peel strength testing and cyclic loading testing. Systematic samples of various assembly structural thickness of Cu/PI were employed and investigated in this study. The statistical values of mechanical performances were calculated and compared. In peel strength, better adhesive performance of the PI film was set as 20 μm and copper to 18 μm. However, the comparative calculations of the better peel performance at 85 °C/85% RH condition. It is expected that through comparison between 85 °C/85% RH and 150 °C after 240h in mechanical reliability, a criterion of lifetime can be predicted by 85 °C/85% RH which has been used to realize the changes occurred during operation or storage in real situations. To compare with the identical structures were maintained at room temperature and normal relative humidity for a period of three years. The results are close to those obtained for the 85 °C/85% RH conditions. It is assured that this test can be applied to predict the lifetime following a period of three years. Most failure regions existed at interface of Cu side in cyclic loading test due to the stress accumulation. The correlation between the crack generation and different structural Cu/PI composite were established on the QC-104 COMETECH test machine via field-emission scanning electron microscopy (FE-SEM). According to the trend, the Cu influence was focused in both attachment and assembly with various PI film. The microstructure evolution, different mechanical reliability vehicle, failure mode and crack generation of Cu in the attachment and assembly with critical PI film thickness. This research is to set up a systematic method to evaluate the mechanical reliability in different construction of Cu/PI composite. In addition, a large amount of data base were collected to identify the relationship of lifetime and to reveal the critical factor of surface improvement for attached Cu/PI in the PCBs and electronic industries. The optimal conditions for the surface cleaning could be pre-controlled in the attachment Cu/PI assembly, and the yield enhancement in fabrication was further conducted. It is expected that the effort and results in this study should provide a potential contribution for PCBs and electronic industries.