The price of gold is hovering near record highs, so it’s expected that manufacturers that use it would like to trim costs wherever possible. As a result, we’re often asked if the amount of gold could be reduced. Well, it depends. There are two ways this can be achieved: by either reducing the plated area or decreasing the thickness of the gold deposit. In certain cases, selective plating can be used to reduce the area where gold is needed.
As for reducing thickness, it depends on the application, many of which are subject to MIL specs or ASTM specs. This is particularly true for gold plated components used in military and aerospace. Commercial and consumer products could be candidates for thickness reduction, however the potential of sacrificing performance and longevity must be considered.
Specifying and maintaining the proper plating thickness is critical to get optimum performance from passive electronic components. Many factors must be considered when specifying thicknesses, including product application, environment, and life expectancy.
For some parts the greatest concern may be insertion and withdrawal forces and life cycle testing. Nickel hardened gold may be more forgiving to forces than its softer counterpart, pure gold, no matter what thickness is used. In this case, thickness is not as big a factor as hardness. But if life cycle testing is critical, then a thicker deposit of .000050” of gold will last more cycles than .000030”.
With other parts, solderability or porosity may be the critical characteristic. When porosity is critical, it is best to have a heavier gold deposit or two layers of gold. Solderability however would be negatively impacted with a higher gold thickness. Gold more than .000050” can cause a brittle solder joint so less gold is best for it to properly bond to the nickel underplate.
Don’t worry if you need high cycles, low forces, good porosity and solderability. A gold deposit with .000050’ gold will give you all the above if the connector is pre-tinned before it is put into use. The pre-tinning will remove most of the gold and preserve the nickel surface with the tin coating. Any remaining gold is removed when it is finally soldered in its application.
Many contact parts are mated only once in a relatively benign environment, making insertion/withdrawal and porosity less important. This is another instance where less gold is sufficient.
So, can thickness be reduced to save money? In some cases, yes. But we must remember that the primary reasons for specifying gold for connector parts are corrosion resistance and conductivity. These factors must be at the center of any decision to reduce thickness. Unless of course you are dealing with military or aerospace components. There’s no leverage here, you are at the mercy of the applicable standards, which dictate the minimum required thickness.