Top 4 Types of Plating Methods for Printed Circuit Boards Manufacturing!

By | Date posted: | Last updated: May 9, 2020

PCB plating is a very important aspect of manufacturing printed circuit boards. It essentially ensures that oxidization and hence deterioration of PCBs is prevented. When it comes to plating methods for Printed Circuit Boards, 4 main types of methods are in vogue. These include:

  • Finger Plating
  • Through-hole plating
  • Reel linkage selective plating
  • Brush plating

Given below is a brief overview of the processes involved in each of these methods:

Finger Plating

Also referred to as protruding partial plating, this method is used for rare metals such as gold to provide lower contact resistance as well as higher abrasive resistance. The process typically comprises of the following steps:

  • First up, the coating is stripped to remove the tin coating of the contact head.
  • The next step involves rinsing it with water
  • This needs to be followed by scrubbing it with abrasive
  • Next activated immersion in ten percent sulfuric acid needs to be initiated
  • After this, nickel needs to be plated on the protruding contact head. It is important to keep the thickness at 4-5μm
  • Cleaning and removing mineral water needs to be undertaken next
  • This needs to be followed by the Gold permeation solution treatment
  • Finally the gold plating needs to be carried out
  • This is, in turn, followed by cleaning and drying.

Through-Hole Plating

Through hole plating is a crucial manufacturing process for the drilling process. When the drill goes through the copper foil and the substrate below it, the resultant heat causes the insulating synthetic resin to melt. In turn, the molten resin collects around the holes. In turn it offers poor adhesion till the time specific techniques are put in place. What works is to use an adherent conductive film on the inner walls of the via. With this method what you are effectively doing is to take away the need for multiple chemical treatments. In fact, this method requires a single application, which needs to be followed by thermal curing which can then be electroplated. The advantage of using the ink is that it has strong adhesion capabilities that can be bonded without too much effort.

Reel Linkage Selective Plating

This method is largely used for selectively plating components such as:

  • Connectors
  • Integrated circuits
  • Transistors and more

You could choose to go with a manual or automatic plating method. The one thing to be remembered, however is that it can turn out to be a fairly costly affair to individually select each pin. It is, therefore, recommended that batch welding be done to render the process cost-effective. The process involves flattening of the ends of the metal foil to a required thickness. Post that it is die-cut, cleaned and then plated. The process of plating is as below:

  • A portion of the metal plate is coated with a resist film
  • The plating is then performed only on the selected copper foil area.

Brush Plating

This is yet another method of selective plating that is widely used. In this plating process whereby a limited area is plated, care is taken to see that not all parts are immersed in the electrolyte. For example, this technique could be used with board edge connectors, where rare metals are plated on selected portions of the printed circuit boards. Brush plating finds a lot of usage in an electronics assembly shop when it comes to repairing waste boards. The process involves wrapping a special anode such as graphite in absorbent material to bring the plating solution to the specific parts that need to be plated.

As the intricacies of the process above reveal, it is imperative that you go with a PCB manufacturer that has the requisite experience in ensuring that the right PCB method be used and that the plating is done correctly and in a cost-effective manner.

Technotronix is one of the leading printed circuit board manufacturer based in the USA. We have over 4 decades of experience in providing innovative PCB manufacturing services using modern technologies and latest machinery. We are adhering to strict high-quality standards and compliant with the RoHS quality management system. We capable to fulfill the varied need of our customer from the simple board to the most complex board for PCB prototype to production.

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