Michail Klimkovic, CEO, XIMEA s.r.o.

Surface Finish for High Frequency-mmWave-5G-RF-MW PCBs

The evolution of internet-enabled mobile, automotive and space application devices has driven innovation in the manufacturing and design of technology capable of high-frequency electronic signal transfer.

Among the primary factors affecting the integrity of high-frequency signals is the surface finish applied on PCB copper pads — a need commonly met through the electroless nickel immersion gold process, ENIG. However, there are well-documented limitations of ENIG due to the presence of nickel, the properties of which result in an overall reduced performance in high-frequency data transfer rate (insertion loss) for ENIG-applied electronics, compared to bare copper.

Other alternatives available in the market involving Palladium (EPIG/EPAG) also show insertion loss in high frequency PCBs.

The ideal choice of surface finish for high frequency PCBs is to have the insertion loss identical to the insertion loss of bare Cu over the 0 – 100+ GHz frequency range.

The insertion loss of Ni-less ENIG-Premium almost exactly identical to the insertion loss of bare Cu ("Non-Lossy") unlike ENIG or EPIG over the 0 – 100+ GHz frequency range.

An innovative, patented Ni-less ENIG-Premium involves a special nano-engineered barrier designed to coat copper contacts, finished with an outermost gold layer (only 2 microinches). It offers better reliability in terms of long shelf-life, up to 6 reflow cycle assembly capability, robust solder joints (optimized intermetallics), etc.

Award-winning Ni-less ENIG-Premium offers optimum performance for high frequency, 5G, HDI, RF, MW PCBs
• No insertion loss due to Ni
• Au wire-bondable
• Better reliability
• Cost-effective
• Eco-friendly (cyanide-free gold solution)