Near-Hermetic High Power Package using Liquid Crystal Polymer for 4-Watt Ka-Band Amplifier with Sparse Thermal Vias for Cost Reduction

This paper presents the design and development of a 10W power package at Ka-band with near a hermetic sealing cavity. The package has a 12x12x0.5 mm copper heat spreader on which Liquid Crystal Polymer films are laminated to form 50Ω feed-thru transition to a mother board. The experiment results demonstrate that a packaged GaAs power amplifier dissipating 10W DC power has the maximum channel temperature of 143.9°C. The Tch temperature is obtained using infrared thermal mapping technique with baseplate temperature at 80°C. Also the effect of using sparse corner vias at the PCB level will be presented as well. By reducing the number of vias at the corners from 196 to 148, a 24.4% reduction, the channel temperature of the packaged amplifier maintains approximately the same temperature. This LCP package will be near-hermetic without extra adhesive and will provide enough power dissipation up to 10W to maintain GaAs device lifetime at Ka-band.