Inkjet-Printed Multilayer Bandpass Filter Using Liquid Crystal Polymer System-on-Package Technology

This paper presents the fabrication of an inkjet-printed multilayer bandpass filter using the liquid crystal polymer (LCP) system-on-package (SOP) technology. The LCP-SOP technology adopted by lamination bonding process reduces the occupied area of a device and is suitable for radio frequency (RF) package applications. The surface morphologies and RF performance of the inkjet-printed silver film on an LCP substrate after the lamination bonding process, which entails applying high temperatures and pressures, were observed and analyzed. Acceptable performance of the inkjet-printed silver film of an optimal lamination bonding condition was 0.69 MPa at 270 °C. Using the inkjet-printing and LCP-SOP technologies, a miniature bandpass filter was created with a minimal S
₂₁
value and a maximal S
₁₁
value of -1.5 and -17.4 dB at 10.6-14.5-GHz passband, respectively. A strain effect of silver line and bandpass filter was also analyzed. The results demonstrated the effectiveness of the proposed design methodology and the fabrication technique.