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.