The first thought that may come to mind concerning gold is for jewelry. However, gold can be used for plating purposes for all types of electrical equipment. There are times when the cost of gold can limit its applications but for the most part, gold plating, when used for decorative purposes, can be less expensive than you would think. Deposits of gold can be changed so as to provide different characteristics of solderability, hardness, color, wear and luster. It will also not tarnish or oxidize.
How it’s Done
Gold plating involves depositing a thin layer of gold onto the exterior surface of another metal by either chemical or electrochemical means. Several finishing methods can be used in the depositing of gold.
Barrel plating uses a barrel filled with electrolytic plating solutions into which the parts are placed. All parts are given a uniform and precise finish as the barrel rotates. This is an efficient and low-cost method of plating and is best for small and durable parts. Rack plating is the better option for parts that are large, complex, or fragile. In this process, parts are arranged on coated metal racks and to which they are fixed with screws, spring fingers, or wires, based on their size, weight, and configuration. The racks are placed in a tank and do not move while the items are being plated.
In reel-to-reel plating, strips of manufactured products or reels of raw material are plated before they are stamped into parts. This is an efficient and economical process which allows for select deposits of metal. Vibratory plating is best suited for small parts with blind holes and threaded areas requiring complete coverage. The parts are placed into special barrels and are lightly agitated so that the solution can be transferred to the substrate.
Gold Types
Gold can be either hard or soft, and the type of gold used for plating depends on the application.
Hard gold is an alloy of 99.7% gold and 0.3% of a hardening agent, most commonly either nickel or cobalt. It is used in applications where the design requirements call for corrosion resistance, electrical conductivity, and solderability. Soft gold is pure gold and has no additives. As it is pliable and easier to solder than hard gold, it is typically used in lead frame wire bonding applications and high-reliability solder applications where hard gold would not be appropriate.
General Metal Finishing was founded over 40 years ago to supply rack and barrel gold electroplating services to machining, glass-to-metal seal, and stamping companies throughout New England. It has since grown in its capabilities to provide other precious metal plating and electro-polishing services to customers around the world. For further information about their services, visit their website at www.pepgenmetal.com.
