Figure 7 shows three-dimensional (3D) and cross-section images of the central region of the
pressure sensor package assembled with the dam-ring approach. Free space for the sensing-channel
was completely reserved in the central area of the plastic pressure sensor package. The top surface of
the silicon membrane was free of EMC contamination, as shown in Figure 7(b). Therefore, the damring
parts successfully shields the inner space of the dam-ring from the overflowing or leakage of fluid
EMC at a high molding temperature of 165 °C. The injected molding pressure pushed the fluid EMC
which squeezed the outer sidewall of the dam-ring during transfer molding process so that the
peripheral borders of the dam-ring had a slight inward deformation. However, the dam-ring was still
tightly bound to the top surface of the pressure sensor. The fluid EMC did not bleed to cover the top
surface of the silicon membrane through the interface between the dam-ring and the top surface of the
pressure sensor. Therefore, the dam-ring performed its function. The slight deformation of the damring
walls can be improved by employing a thicker dam-ring sidewall to enhance its bending strength.
The packaging dimensions of the packaged pressure sensors, sacrifice-replacement and dam-ring
approaches, are 4 × 4 × 1.5 mm3 and Table 1 shows the basic dimensions of the both packaged
pressure sensors. Table 2 shows the dimension comparisons between our proposed two packaged
pressure sensors and the commercialized pressure sensor packages. Both packaging volumes of the
proposed two packaged pressure sensors are about seven times less than the commercialized pressure
sensor packages.