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Four Summaries of Special plating Methods for PCB Circuit Boards

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Finger-row Plating

Often need to rare metal plating on the board edge connector, board edge outstanding contact or gold finger to supply lower touch resistance and higher wear resistance, the skill is known as finger-row plating or outstanding part of the plating. Often gold plating in the inner layer of nickel plating for the board edge connector outstanding contacts, gold finger or board edge outstanding part of the selection of craft or active plating skills, the current touch plug or gold plating on the gold finger has been basal plating, lead plating, plating button instead. The process is described as follows.

a, Strip the coating to remove the tin or tin-lead coating on the outstanding contacts;

b, Rinsing with washing water;

c, Wiping with abrasive;

d, Activation in 10% sulphuric acid;

e, Plating nickel thickness of 4-5 μm on outstanding contacts;

f, Cleaning to remove mineral water;

g, Gold impregnation solution treatment;

h, Gold plating;

i, Cleaning;

j, Drying.

Through-hole Plating

There are a variety of ways to drill holes in the substrate to establish a layer of plating on the hole wall to meet the requirements, which is known in industrial use as hole wall activation, the commercial production process of its printed circuits require a number of central storage tanks, each of which has its own control and maintenance requirements. Through-hole plating is a necessary manufacturing process subsequent to the drilling manufacturing process, when the drill bit drills through the copper foil and the substrate below it, the heat generated causes the insulating synthetic resin that makes up most of the substrate substrate to melt, and the melted resin and other drilling debris builds up around the holes to coat the newly exposed hole walls in the copper foil, which is in fact detrimental to the surface of the plating that follows. Melted resin will also be left on the substrate hole wall under a layer of thermal axis, it for most activators have embodied the poor adhesion, which requires the development of a class of similar to remove stains and etch back the chemical effect of the skills.

More suitable for printed circuit board prototyping of an approach is to use a specially planned low-viscosity ink, used in each through-hole walls constitute a high adhesion, high conductivity of the film. This eliminates the need for multiple chemical treatment processes, and only one application process, followed by heat curing, is able to form a continuous overlay on the inside of all the hole walls, which can be plated directly without further treatment. The ink is a resin-based substance that is intensely adhesive and bonds effortlessly to most heat-polished hole walls, thus eliminating the process of etching back.


Reel-linked Pick-and-plating

Electronic components pins and pins, such as connectors, integrated circuits, transistors and flexible printed circuits, etc. are selected to pick plating to obtain outstanding touch resistance and corrosion resistance. This plating method can choose the craft method, can also choose the active method, individually for each pin to select the plating is very expensive, so it is necessary to choose the batch welding. Generally, the metal foil will be flattened into the required thickness of the ends of the punch, the choice of chemical or mechanical methods for cleaning, and then selective selection of nickel, gold, silver, rhodium, button or tin-nickel alloy, copper-nickel alloy, nickel-lead alloy, etc. for successive plating. In selective plating this plating method, first in the metal copper foil plate does not need to plating part of the overlay a layer of resist film, only in the selected part of the copper foil for plating.

Brush Plating

Another method of selective plating is called "brush plating". It is a kind of electrodeposition skill, not all parts are submerged in the electrolyte during the plating process. In this plating technique, only a limited area is plated without any effect on other parts. Generally, rare metals are plated on selected portions of the printed circuit board, such as areas like board edge connectors. Brush plating is more commonly used when repairing discarded circuit boards in electronic assembly shops. A special anode (chemically inactive, e.g. graphite) is wrapped in an absorbent material (cotton swabs) and used to carry the plating solution to the area to be plated.

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