The classification of PCB circuit board gold fingers and the introduction of gold plating process

Gold Finger: (Gold Finger or Edge Connector) Insert one end of the PCB board into the connector card slot, and use the connector pin as the outlet of the pcb board to connect to the outside, so that the pad or copper skin is in contact with the pin at the corresponding position To achieve the purpose of conduction, and nickel-gold plated on this pad or copper skin of the pcb board, it is called a gold finger because it is in the shape of a finger. Gold was chosen because of its superior conductivity and oxidation resistance. Abrasion resistance. However, because of the extremely high cost of gold, it is only used for partial gold plating such as gold fingers.


Gold finger classification and identification, characteristics

Cheat classification: conventional cheats (flush fingers), long and short cheats (that is, uneven cheats), and segmented cheats (intermittent cheats).

1. Conventional golden fingers (flush fingers): rectangular pads with the same length and width are arranged neatly on the edge of the board. The following picture shows: network cards, graphics cards and other types of physical objects, with more gold fingers. Some small plates have fewer gold fingers.

2. Long and short golden fingers (i.e. uneven golden fingers): rectangular pads with different lengths at the edge of the board 3. Segmented golden fingers (intermittent golden fingers): rectangular pads with different lengths at the edge of the board, and the front section disconnect.

There is no character frame and label, and it is usually a solder mask opening window. Most shapes have grooves. The golden finger partly protrudes from the edge of the board or is close to the edge of the board. Some boards have gold fingers at both ends. Normal gold fingers have both sides, and some pcb boards only have single-sided gold fingers. Some golden fingers have a wide single root.

At present, the commonly used gold finger gilding process mainly includes the following two types:

One is to lead from the gold finger end as a gold-plated wire. After the gold plating is completed, the lead is removed by milling or etching. However, the products produced by this kind of process will have lead residues around the gold fingers, resulting in exposure of copper, which cannot meet the requirements of not allowing exposure of copper.

The other is to lead wires not from the gold fingers, but from the inner or outer layers of the circuit board connected to the gold fingers to achieve gold plating of the gold fingers, thereby avoiding copper exposure around the gold fingers. However, when the circuit board density is very high and the circuit is very dense, this process may not be able to make leads in the circuit layer; moreover, this process is powerless for isolated golden fingers (that is, the golden fingers are not connected to the circuit).