Batch-fabricated high-power rf microrelays with direct on-PCB packages

This paper describes a process for batch manufacturing, assembly, and packaging of metal alloy microrelays directly on printed circuit board (PCB) substrates for high-power radio frequency (RF) applications. Stainless steel cantilevers with Pt-Rh tips are mounted on Rogers 4003 PCB substrates to demonstrate the approach. A multilayer PCB design allows for the use of subsurface metal layers to transmit the RF signal into and out of the sealed encapsulation. The electrostatically actuated microrelays with 8.4-mm ² footprints have 78-V pull-in voltage and 1.1-Ω on-state resistance. Packaged microrelays exhibit down-state insertion loss and up-state isolation better than $-$ 0.25 and-15 dB, respectively, for frequencies up to 5 GHz. Packaged devices remain functional up to 20-W RF power under hot switching conditions. The high power lifetime of the microrelays is 10913 cycles for 1-W incident RF power in 1-s pulses and 8414 cycles for 10-W incident RF power in 0.1-s pulses. The impact of device encapsulation and multilayer PCB substrate on device performance is addressed.