Where Can you Find a Suitable Surface Finish for 5G, High Frequency, and High-Density Applications?
By Kunil Shah, Ph.D., chief scientist, LiloTree
Key Summary
• High frequency and high density electronics require surface finishes that minimize insertion loss and maintain signal integrity.
• ENIG is widely used but its nickel layer reduces performance due to higher conductor losses and ferromagnetic effects.
• Nickel’s properties can degrade high-frequency data transfer compared to bare copper surfaces.
• Selecting a finish for 5G applications requires low insertion loss, long shelf life, cost effectiveness and high reliability.
• Alternatives such as EPIG, EPAG and DIG exist, though each has limitations for advanced applications.
The advent and ongoing evolution of internet-enabled mobile devices has continued to drive innovation in the manufacturing and design of technology capable of high-frequency/high-density electronic signal transfer. The combined requirements for both fast, always-on data transmission, and small geometric form-factors can be difficult to satisfy without compromised performance and signal loss. Among the primary factors affecting the integrity of high frequency signals is the surface finish applied on PCB copper pads – a need commonly met by technology manufacturers through the electroless nickel immersion gold process, ENIG. However, a well-documented limitation of ENIG is its insertion loss due to the inferior conductivity of nickel over copper, leading to higher conductor losses. Additionally, nickel’s ferromagnetic properties adversely affect circuit performance. The result is an overall reduced performance in high-frequency data transfer rate for ENIG-applied electronics, compared to bare copper. The selection criteria of surface finish for 5G, high frequency, high density application involves minimal insertion loss, long shelf life, cost-effective and high reliability. There are few options (EPIG, EPAG, DIG, etc.) available in the market and there are limitations involved with each offering. You can learn more at IPC APEX EXPO Technical Conference Session 15 (Surface Finishes 1) on Wednesday, February 5 at 1:30-3:00 pm. For more information, visit www.ipcapexexpo.org.
ENIG introduces insertion loss because nickel has lower conductivity than copper and its ferromagnetic properties weaken circuit performance.
These applications require minimal insertion loss and high reliability to maintain fast, consistent data transmission in compact designs.
Nickel increases conductor losses and its ferromagnetic behavior negatively impacts high frequency circuit performance compared to bare copper.
A suitable finish should provide low insertion loss, long shelf life, cost effectiveness and high reliability for advanced applications.