Letter 29071

ENIG vs. ENAG  

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I am evaluating the quality and reliability of two plating processes used in PCB manufacturing specifically at the plating process:

* What is the difference between Electroless Ni Immersion Au versus Electroless Ni Autocatalytic Au plating processes?
* What is the process flow and chemistry differences?
* What are the end result quality differences?
* What are the surface morphology differences?

Filmore A. Ochoco
laminate PCB user - Warren, New Jersey, USA

We are in the manufacture of PCBS with ENIG plating .

Recently we have experienced black spots on large size pads of 12 mm and 16 mm in Finished Board.
Question : How to remove this tarnishing . If we do any rework on ENIG , Is it reliable ???

HARAGOPAL
ECIL - Hyderabad India

Filmore: I'm a little out of the loop on progress in ENAG, since it is both relatively new and proprietary, and you need to be doing it yourself to keep up. In general, though, the biggest advantage of an autocatalytic process is that the thickness is not as limited because you can build gold on gold rather than the operation slowing to a halt as soon as no more nickel is exposed.

Haragopal: See the previous disclaimer, but I would suspect the EN as being unsatisfactory and porous. If an area is reworked, it would seem that you could use brush electroplating of gold; you might contact brush plating suppliers about that.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

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