A tiny plastic package of piezoresistive pressure sensors constructed by sacrifice-replacement approach

In this study, a tiny plastic package of piezoresistive pressure sensor was fabricated and demonstrated by employing the sacrifice-replacement approach. A JSR THB- 151N photoresist layer with a thickness of 150 mum was deposited on the silicon membrane of the pressure sensor by using a two-stage spin-coating procedure. Following a high- temperature transfer molding process, the photoresist is removed and the package is cured at 175degC for two hours. The performance of the packaged sensor is evaluated both experimentally and numerically using a finite element analysis method. Experimental observations reveal that the silicon membrane of the pressure sensor is completely free of epoxy molding compound following the transfer process. Hence, the effectiveness of the photoresist layer in shielding the membrane during the molding process is confirmed. The experimental and numerical results indicate that the packaged sensor has a linear response (R²=0.9999) over a pressure range of 0-100 psi at room temperature.