Packaging methodology for RF devices using a BCB membrane transfer technique

Abstract

This paper presents a whole benzocyclobutene (BCB) film encapsulated 0-level packaging using a wafer level BCB bonding technique. The wafer-scale membrane transfer technique using silicon carrier wafers was used to make BCB membrane caps for encapsulation placed above the device wafers. The BCB multiple coating process using CYCLOTENE 4026-46 was developed to make an encapsulation cap. The average height of the BCB cap was 40 µm with a little curvature on the membrane for the dimension of 2 mm × 3 mm. The RF characteristics using coplanar waveguide (CPW) lines were measured to evaluate the effect of BCB film packaging and the results were compared with those of pyrex #7740 glass packaged CPW lines. It shows that the insertion loss (S12) of BCB-packaged CPW lines is better than that of pyrex glass packaged CPW lines at high frequencies. The insertion loss change of CPW lines by BCB film packaging is below 0.01 dB up to 90 GHz, while the glass-packaged CPW lines show about 0.1 dB deviation from 20 GHz to 110 GHz.