Hard Gold plating technology discussion

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The definition of the hard gold plating

First of all we should know what is the hard gold plating.
Hard Electrolytic Gold is a layer of plated gold on the surface of rigid PCB.
And this Hard Electrolytic Gold can protect circuit layer due to it over a barrier coat of nickel.

The applications of Hard Electrolytic Gold

Most of hard materials were very durable.
This situation some with Hard Gold, also extremely durable.
So the most commonly applied to high-wear areas.
For example the edge connector fingers or keypads.

The parameters of Hard Gold Plated process of rigid PCB

If you have learned the ENIG process of rigid PCB, you may know the protect layer cannot be controlled very exact.
But this situation is different with Hard Gold Plated process.
In other words, the Hard Gold Plated protect layer can vary by controlling the duration of the plating cycle.

Two factors related to The thickness of Hard Gold plated technology

First of all we should know the thickness of nickel.
The typical minimum values for rigid PCB fingers are 30 μin gold over 100 μin nickel for Class 1 and Class 2, 50 μin gold over 100 μin nickel for Class 3.
But Hard Gold can not plated so thick.
Because most not generally applied to solderable areas, and the plated cost and hard cost material cost very expensive.
Then is it relatively poor solderability.

Rigid PCB experts explain the thickness of Hard Gold Plated

Every customer has each own Hard Gold Plated requirement.
But not all customers know the maximum thickness.
So Emma have asked our 4MCPCB rigid PCB experts, about the thickness of the
Hard Gold Plated.
He told Emma that IPC as a professional international PCB standard, 17.8 μin is the maximum thickness to be solderable.
Then he also mentions that thus the maximum number, but not the idea thickness or Hard Gold Plated.
So consider using on surfaces to be soldered, the recommended nominal thickness should be about 5-10 μin.