Hermetic plastic molded MEMS device package and method of fabrication

摘要

A hermetically packaged microelectromechanical system (MEMS) device has a substrate with an assembly pad (101) and a plurality of terminals (102); a chip (110) with a MEMS mechanical element (111) of a first height (111a) assembled on the pad and connected to the terminals by wires (120) with an insulating coat (121); a ridge (130) on the substrate, which surrounds the MEMS element (111) with a second height (130c) greater than the first height and comprises a plastic compound (131) filled with particles (132) and a surface (130a, 130b) having an adhering moisture-impermeable seal layer (133); and a moisture-impervious lid (140) attached to the ridge by moisture-proof bonds (150, 151), sealing the volume (160) enclosed by the lid, the chip, and the metalized ridge as a hermetic space for the MEMS element (111).

主权项

1. A method of packaging a microelectromechanical system (MEMS) device, comprising:
providing a MEMS device chip on a pad of a leadframe substrate and connected with conductive bonding wires extending from the chip to the leads, the chip having a micromechanical element extending a first height above an upper surface of the chip; molding on the substrate a ridge surrounding the micromechanical element and enclosing the leads, the ridge having a second height above the surface greater than the first height, the molding process using a compound comprising a polymerizable resin and metal filler particles; depositing a moisture-impermeable seal layer over an upper surface of the ridge and over downwardly extending surfaces of the ridge surrounding and facing the micromechanical element, and joining the upper surface of the chip with a moisture-proof juncture spaced from and continuously surrounding the micromechanical element; and bonding a moisture impervious lid to the upper surface of the ridge, spaced above and continuously surrounding the micromechanical element with a moisture-proof bond, thereby enclosing the micromechanical in a moisture-sealed volume defined by facing surfaces of the lid, the chip upper surface, and the seal layer over the downwardly extending ridge surfaces.