This paper proposes a new methodology to detect the gas-leakage and the corresponding diffusion coefficient of PDMS. We use PDMS instead of Pyrex 7740 glass to seal the backside V-groove of pressure sensor chips. We put the sensor into a pressure testing machine and pressurize with CO2 at 300 psi. By observing output voltage, the time of CO2 permeated into cavity of the sensor was easily to find. In this paper, we use two PDMS membrane with different thickness, 45.mu.m and 500.mu.m, to package the sensors and explore the gas-leakage of PDMS membrane. The mathematical model for the leaking process shows that the diffusion coefficients D are 7.49*10/sup -10/m2 /sec for 45.mu.m thick PDMS and 1.38*10/sup -9/m2 /sec for 500.mu.m thick PDMS, respectively.
Proceedings of the 4th Asia Pacific Conference on Transducers and Micro-Nano Technologies (APCOT 2008)，4p.