MEMS packaging technology using a cavity structure for mass production

摘要

Lower cost package for microelectromechanical systems (MEMS) have been required, because the cost portion of the MEMS package is more than 30 % of the cost of a MEMS product. For the reason, cost effective MEMS packaging platforms are proposed in this paper for high volume production. Two package platforms are developed using an epoxy molding compound (EMC) onto copper (Cu) pre-plated lead frames (L/F). One is a cavity wall type with attaching a flat lid. The other is an in-frame type with attaching a folded cap lid. Finite element method (FEM) numerical modeling is performed to anticipate the mechanical warpage and stress of the packages. The finally assembled packages are tested for wire pulling, lid pulling, hermetic test, and reliability tests. The wire bonding strength was improved in about 40 % using plasma cleaning before wire bonding. Through a lid pulling test, the lid bonding strength of 2.40 kgf in average was obtained using an epoxy adhesive. Finally, all samples of the packages passed the reliability tests of the TC, HAST and HST, standardized by JEDEC (Joint Electron Device Engineering Council). Also, this cavity package showed excellent hermeticity through leak test.