Of course gold finger PCB doesn't mean there is a PCB with a golden finger, you can't image that. Gold finger, also called Edge connector or connecting finger, is a row of sodering pads which looks like "fingers" used to insert into a slot where conducted with metal spring sheets. While it often require high standard on surface scratch resist and conducting performance, so a layer of gold and Ni will be applied.
Such kind of circuit board are mostly seen in the graphic card PCB and memory bank PCB.
Options on gold finger surface
Hard gold plated (NI-AU): with a hard gold layer of 30U". With hard gold treatment, the gold finger surface can have a high performance on scratch resistance which means it can be slide in-and-out many times with out quality issue. The other hand, hard gold treatment has reletively higher requirements on manufacturing technology and consumption on raw materials, so the manufacturing cost will rise up higher accordingly.
immersion gold: some PCB with gold finger do not need frequent slide in-and-out, so thick layer of gold is not necessary. Therefore, immersion gold (soft gold, thickness 2-3U") is used instead to reduce PCB manufacturing cost.
Bevelling of Gold finger edge
Bevelling treatment are made for easier slide-in to motherboard, as shown below
Welcome to send any PCB manufacturing inquiry to us at inquiry@cheemau.com