Abstract:

A novel inverse approach is proposed for in situ measurement of gas diffusion properties of polymeric seals used in microelectromechanical systems (MEMS) packages. The cavity pressure evolution of a polymer-sealed MEMS package subjected to a constant bombing pressure is documented as a function of time using classical interferometry, and the diffusion properties of the polymeric seal are subsequently determined from the measured pressure history. A comprehensive numerical procedure for the inverse analysis is established considering three diffusion regimes that characterize the leak behaviour through a polymeric seal. The method is implemented to determine the helium diffusivity and solubility of a polymeric seal.

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