Thermal Management in High Performance RF and Microwave PCBs

As new RF and microwave systems evolve, we are seeing a greater need for effective thermal management and significantly higher RF performance from Printed Circuit Boards (PCB’s) and subsystems; at the same time these systems are required to decrease in mass and still offer greater functionality than ever before. Constraints like these are often most acute in applications where Size, Weight and Power (SWaP) are high priorities such as military and aerospace and typically include RF power amplifiers and phased array TxRx modules. This paper reviews the various methods of thermal management and reviews in detail the advantages of “Coin” technology versus traditional thermal via technology.

High density active power devices, such as GaN power transistors, can dissipate significant heat. One of many roles that the PCB has to perform is to channel heat from the underside of the semiconductor device through to the chosen heatsinking scheme as efficiently and effectively as possible. The design challenge is how best to accomplish this while achieving the other tradeoffs required such as RF performance, manufacturability and cost.