When you open a computer PCB case, you will find graphics cards inserted in the slots. These PCB assemblies have a neat, narrow, and long row of PCB pads on the edge. We call the rectangular row of PCB pads "gold fingers" because these conductive pads used for connection look like fingers.
Compared with other PCB pads, PCB gold fingers have a higher gold thickness. According to IPC-4556, the normal PCB gold finger thickness is 32u" (microinch), and the gold thickness range of PCB gold fingers is 3u" to 50u".
Gold on the PCB gold fingers is a gold alloy, which has a higher hardness than immersion gold.
PCB gold fingers can be classified into three types:
Normal PCB gold fingers - most common PCB gold fingers with a level and even array. The PCB pads have the same length, width, and space.
Uneven PCB gold fingers - the PCB pads have the same width but different lengths, and sometimes, different spaces.
Segmented PCB gold fingers - the PCB pads have different lengths, and the gold fingers are segmented.
PCB gold fingers is a good option for PCB board connection
PCB gold fingers provide a direct connection to the PCB boards with the system/device. This connection has better conductivity and mechanical strength than PCB connectors and wires. PCB gold fingers are used for connection with slots and interfaces of commercial and industrial systems and devices because they provide:
Excellent conductivity because of the direct board connection and more gold thickness,
Strong wear resistance so that the PCB can be plugged in and out thousands of times,
Good oxidation resistance due to the hard-gold plating process to the PCB pads.