Measurement of pressure distribution during MEMS and Flip Chip encapsulation

This article investigates a new pressure measurement method usable during packaging of electronic systems. With pressuresensitive multilayers it is possible to determine the pressure distribution on the surface of mold cavities and on various electronic substrates during packaging processes. The pressuresensitive multilayer is based on commercially available surface pressure indicating fi lms such as Fuji Prescale®1 (www. sensorprod.com) that change color directly proportional to the amount of pressure applied. Homogenous pressure distribution within the molding cavity is of particular importance for encapsulation of mechanically sensitive electronic components, e.g., MEMS sensors, bare dies and Flip Chips. With the implementation of specially multilayered sensor fi lms, a fast estimation of the pressure distribution within the cavity will be possible. We successfully used the new sensor concept to investigate industrial transfer molding processes with epoxy molding com pounds (EMC). On distinct points of the mold cavity conventional piezo pressure sensors have been applied to get a time-dependent pressure signal.