Golden Finger PCB refers to a printed-circuit board whose edge carries a row of gold-plated contact pads. These pads (the "fingers") are inserted into a mating connector to provide a low-resistance, corrosion-free, high-wear path for power and high-speed signals between boards or sub-systems.

• Structure
  • Located on the board edge; can be single- or double-sided
  • 3-6 µm nickel under-layer + 30-100 µin (0.75-2.5 µm) hard gold (Au-Co or Au-Ni alloy)
  • 20°-45° bevel is normally ground on the tip to ease insertion and reduce abrasion
• Function
  • Acts as a pluggable edge connector that can survive ≥1,000 insertion/removal cycles
  • Provides excellent conductivity (<10 mΩ contact resistance) and long-term oxidation resistance
• Typical uses
  • RAM modules (DDR4/DDR5), graphic cards, PCIe cards, disk-drive carriers, industrial backplanes, USB sticks, smart-card sockets--any application where a sub-board must be quickly and repeatedly connected to a motherboard or backplane
• Manufacturing note
  • After solder-mask, only the finger area is exposed; nickel is electroplated first, then hard gold; finally the edge is bevelled. The rest of the board can receive any normal surface finish (ENIG, OSP, etc.)