濕氣引起 eWLB 封膠晶圓膨脹研究

The electrical packaging methods follow the market requirement and technology trend. Therefore the consumer electronics progresses from P-DIP, PLCC, PQFP, through BGA, LBGA and VFBGA, to FCBGA that is packaged by flip chip structure. In order to meet the trend of the cost down or small/thin requirement, the CSP packaging was developed. Because of the trace width upgrading speed in back-end packaging is much faster than that of PWB, the WLCSP packaging was developed following bumping technology to meet the requirements of better electrical function, shorter assembling process flow and cost down issue. For the same reason, the trace width upgrading speed in front-end packaging is much faster than that of back-end packaging, the bump pad pitch on WLCSP is getting smaller and smaller, and even smaller than the solder ball manufacturing capability. Thus, the development and application of WLCSP products are restricted. Infineon’s Brunnbauer et. al. [1] announced a new processes and structure compared to the standard wafer level package, namely the fan-out type eWLBTM (embedded wafer level ball grid array) reconfigurated by molding compound. It is well known that the polymer is easy to sorb moisture, and some of the properties will be therefore changed more or less. This thesis is primarily based on the processes and structure of Infineon eWLBTM semi-product to discuss the moisture sorption and swelling impact at different temperature / humidity environments (30℃/60%RH, 85℃/60%RH, 85℃/85%RH). It is known from the experimental results that the moisture sorption and swelling are indeed involved by the environmental temperature and humidity. There are the closely impact to moisture sorption, the moisture sorption follows the Non-Fickian diffusion model, the humidity impact to swelling is more critical than that by temperature. Finally the moisture diffusion coefficient and the activation energy are found from this experiment, also the fitting equations of the time related moisture sorption rate and the time related strain, and the coefficient of moisture expansion.