Zero-level packaging using BCB adhesive bonding and glass wet-etching for W-band applications

A small size zero-level packaging method, by using wafer-level benzocyclobutene (BCB) adhesive bonding and a pyrex glass wet-etching technique, is presented. A simple process was developed to make a pyrex glass to have housing cavities and BCB sealing ring for a packaging. During a wet-etching of glass for making a cavity and pad feedthroughs, BCB was protected by 1.2 μm-thick AZ1512 photoresist. To estimate a pyrex 7740 packaging material in W-band, a 50 W coplanar waveguide (CPW) was designed and an insertion loss (S₁₂) was measured. The insertion loss change of CPW lines by the fabricated package is below 0.1 dB from DC to 110 GHz.