Study of rapid cure BGA mold compound on warpage with shadow moire

For a plastic package as a whole, more than 70% of package volume is made of plastic material, such as mold compound, solder mask and die attach adhesive. Typically, they are thermosetting materials whose chemo-rheological, exothermic and thermo-mechanical characteristics are highly temperature dependent. PBGA's asymmetric package design has encountered with a material-and process induced problem during the manufacturing, i.e. warpage. Therefore, analyzing the characteristics of rapid cure mold compound in advance can provide more information for process optimization (warpage control). Some instrument are capable of characterizing these behaviors, for example, Capillary Rheometer (viscosity), DSC (curing condition), TMA (CTE), DMA (visco-elasticity), RVSI (warpage) and shadow moire (real-time warpage changes during reflow). In this study, two materials were firstly compared instrumentally. They are regular and rapid cure mold compounds, i.e., different gelation time. Secondly, process effect on the warpage of packages (35/spl times/35 mm with 4-ply substrate) was investigated by RVSI. Finally, the real-time warpage measurement was conducted via shadow moire with simulated surface mount reflow profile.