Method of encapsulating a saw device

Abstract

A bi-layer encapsulation system for a planar acoustic wave device, e.g., a SAW device, employs a layer of controlled particles to contact the active surface of the SAW device, and another layer to lock the first layer in place. A back surface of the device is bonded to a supporting substrate, e.g., a ceramic backing. The particles may be glass microspheres of a nominal 50 micron size. A layer of microspheres cover the acoustically active area of the device. Then, an epoxy or other suitable potting material covers the glass microspheres and bonds to the device and to the supporting substrate. The glass spheres may be solid glass or balloon-like microspheres filled with nitrogen or another gas. A second layer of glass microspheres may be applied over the first layer and around the edges of the first layer. This layer may contain an appropriate B-stage epoxy or a commercially available syntactic foam material. A plurality of devices can be packaged and encapsulated together while in wafer form. A first wafer on which the devices are formed is laminated to a second ceramic wafer. Streets and alleys are removed, and the devices are wire bonded to conductive traces on the ceramic wafer. The devices are encapsulated while the ceramic wafer is still intact.

Dependencies are inferred from the claim text.