Hermetically Sealed Glass Package for Highly Integrated MMICs

A novel hermetically sealed RF packaging concept based on glass is presented. Using the laser induced deep etching (LIDE) technology enables the fabrication of glass vias without degrading the mechanical stability as micro-cracks are completely avoided. Furthermore, aspect ratios of up to 1:10 make this technology superior over conventional packaging solutions for the upper millimeter wave regime beyond 150 GHz. As an initial design demonstration, this paper shows a vertical RF-transition through the glass substrate using Through-Glass Vias (TGVs) with an aspect ratio larger than 1:6. The realized prototypes intended for highly efficient LO/VCO distribution within the glass package show excellent reproducibility with a maximum insertion loss of 0.4 dB up to 40 GHz. In addition, a very compact RF-interconnection from PCB to the glass package using solder balls is presented. The simulation of the RF-transition is in good agreement with the measured reflection and transition coefficient not exceeding -15 dB and -1.5 dB up to 35 GHz, respectively.