It is often necessary to plate rare metals on board-edge connectors, board-edge protruding contacts, or gold fingers to provide low contact resistance and high wear resistance. This technology is called finger strip plating or protrusion plating. Gold is usually plated on the protruding contacts of board-edge connectors with nickel as the inner layer. Manual or automatic electroplating technology is adopted for gold fingers or board-edge protrusions. Currently, gold plating on contact plugs or gold fingers has been replaced by rhodium plating, lead plating, and palladium plating. The process is described as follows:(1) Strip the coating: Remove the tin or tin-lead coating on the protruding contacts(2) Cleaning: Rinse with water(3) Scrubbing: Scrub with an abrasive(4) Activation: Immerse in 10% sulfuric acid(5) Nickel plating on protruding contacts: Thickness of 4 - 5μm(6) Cleaning: Remove mineral water residues(7) Gold penetration solution treatment(8) Gold plating(9) Cleaning(10) Drying

There are various methods to form a satisfactory electroplating layer on the hole walls of drilled substrates, which is called hole wall activation in industrial applications. The commercial production process of printed circuits requires multiple intermediate tanks, each with its own control and maintenance requirements. Through-hole plating is a necessary subsequent process after drilling. When the drill bit passes through the copper foil and the underlying substrate, the generated heat melts the insulating synthetic resin that constitutes the matrix of most substrates. The molten resin and other drilling debris accumulate around the holes and coat the newly exposed hole walls on the copper foil, which is actually harmful to the subsequent electroplating surface. The molten resin also leaves a layer of thermal residue on the substrate hole walls, which shows poor adhesion to most activators. This requires the development of technologies similar to decontamination and etch-back chemical effects.

A more suitable method for printed circuit board prototype production is to use a specially designed low-viscosity ink to form a high-adhesion and high-conductivity film on the inner wall of each through-hole. This eliminates the need for multiple chemical treatment processes; only one application step followed by thermal curing is required to form a continuous film on the inner side of all hole walls, which can be directly electroplated without further treatment. This ink is a resin-based substance with strong adhesion, which can be easily bonded to most thermally polished hole walls, thus eliminating the etch-back step.

Pins and headers of electronic components, such as connectors, integrated circuits, transistors, and flexible printed circuits, all use selective plating to achieve good contact resistance and corrosion resistance. This electroplating method can be manual or automatic. Selective plating of each pin individually is very expensive, so batch processing must be adopted. Usually, the two ends of the metal foil rolled to the required thickness are punched, cleaned by chemical or mechanical methods, and then continuously plated selectively with metals such as nickel, gold, silver, rhodium, palladium, or alloys such as tin-nickel, copper-nickel, and nickel-lead. In the selective plating method, a resist film is first applied to the parts of the copper foil that do not need electroplating, and electroplating is only performed on the selected parts of the copper foil.