Simultaneous flip chip underfill and encapsulation

This article describes work carried out at Fraunhofer IZM to investigate the feasibility of combining the underfill process with encapsulation of the flip chip in a single vent-molding process step. A vent hole in the substrate beneath the chip permits existing transfer molding equipment to be used with minor modifications to carry out the process. The use of existing equipment and combining underfill and encapsulation into a single process both potentially reduce costs. Since the same material is used for encapsulation and underfilling, the single-process approach allows selecting materials that will provide the best coefficient of thermal expansion (CTE) match for improved reliability.