Design, fabrication and characterization of BCB polymer embedded 60 GHz parallel-coupled BPF

This paper presents 60 GHz BCB embedded bandpass filter (BPF) with a merit of the reduction of interconnect of Si-based System-In-Package (SIP) for millimerter-wave applications. Photosensitive BCB polymers placed between two Si substrates of the SIP serve as both bonding layer and RF substrate material of some embeddable passive components such as inductor, capacitor and filter. Indeed, it was chosen due to low dielectric constant, low tangent loss at higher frequencies, its multilayer manufacturability and easy bonding capability. For RF characterization of manufactured BCB embedded proto-type filter, vertical transition through BCB was designed and implemented to minimize signal loss from microstrip mode of filter to CPW one of probe. The total size of implemented embedded filter was 7.5 mm × 3.4 mm × 0.3 mm. The insertion loss of −13 dB including probe-toprobe loss and the return loss of −18 dB were measured at the center frequency of 65.5 GHz. In addition, the implemented filter has shown the 4 % 3-dB bandwidth at the same center frequency.