Four methods of electroplating in circuit board

There are four main electroplating methods in circuit board, namely: finger row electroplating, through-hole electroplating, roller linked selective plating and brush plating.
Here is a brief introduction:
Finger Plating:
Rare metals need to be plated 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 row plating or protruding part plating. Gold is often plated on the protruding contact of the board edge connector whose inner coating is nickel. The gold finger or the protruding part of the board edge adopts manual or automatic plating technology. At present, the gold plating on the contact plug or gold finger has been replaced by plating, lead and button.
It refers to row electroplating, and its process is as follows:
Peel off the coating and remove the tin or tin lead coating from the protruding contact
Rinse with cleaning water
Scrub with abrasive
The activated carbon is contained in 10% sulfuric acid
The nickel plating thickness on the protruding contact is 4-5 μ m
Clean demineralised water
Gold osmotic solution treatment
gold-plated
clean
dry
Through hole plating:
There are many methods to establish a satisfactory electroplating layer on the hole wall of substrate drilling, which is called hole wall activation in industrial application. The commercial production process of printed circuit requires multiple intermediate storage tanks, and each storage tank has its own control and maintenance requirements. Through hole electroplating is a necessary subsequent manufacturing process of the drilling process. When the drill bit drills through the copper foil and its underlying substrate, the heat generated melts the insulating synthetic resin constituting most of the substrate matrix, and the molten resin and other drilling fragments accumulate around the hole and are coated on the newly exposed hole wall in the copper foil. In fact, this is harmful to the subsequent electroplating surface. The melted resin will also leave a layer of hot axis on the hole wall of the substrate, which shows poor adhesion to most activators, so it is necessary to develop a kind of technology similar to stain removal and corrosion back chemistry.
One method more suitable for pcb prototype production is to use a specially designed low viscosity ink to form a high adhesion and high conductivity coating on the inner wall of each through hole. In this way, there is no need to use multiple chemical treatment processes. Only one application step and subsequent thermal curing can form a continuous coating on the inner side of all hole walls, which can be electroplated directly without further treatment. This ink is a resin based material, which has strong adhesion and can be easily bonded to most hot polished hole walls, thus eliminating the step of back etching.
Roller linkage type selective plating:
Pins and pins of electronic components, such as connectors, integrated circuits, transistors and flexible printed circuits, are selectively plated to obtain good contact resistance and corrosion resistance. This electroplating method can be manual or automatic. It is very expensive to select each pin separately, so batch welding must be adopted. Generally, both ends of the metal foil rolled to the required thickness are punched, cleaned by chemical or mechanical methods, and then selected for continuous electroplating, such as nickel, gold, silver, rhodium, button or tin nickel alloy, copper nickel alloy, nickel lead alloy, etc. In selecting the plating method, first, a layer of resist film is coated on the part of the metal copper foil plate that does not need to be plated, and only the selected copper foil part is plated.
Brush plating:
Another method of selective plating is called "brush plating". It is an electrodeposition technology. Not all parts are immersed in the electrolyte in the electroplating process. In this electroplating technology, only a limited area is electroplated without any impact on the rest. Typically, rare metals are plated on selected parts of the printed circuit board, such as areas such as board edge connectors. Brush plating is more used in electronic assembly workshop to repair waste circuit boards. A special anode (chemically inactive anode, such as graphite) is wrapped in an absorbent material (cotton swab) to bring the electroplating solution to the place where electroplating is required.

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sales@commax-tech.com

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Keyword：Circuit Board   Plating   Finger Row Plating   Through Hole Plating   Reel Linked Selective Plating   Brush Plating   Commax-Tech Electronic