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TOC levels in PCB acid copper baths
Q. Hello,
We are a large PCB mfg. We are currently reviewing our plating procedures and are discussing TOC levels in the baths. I an familiar with TOC levels being maintained below 4000 ppm but one of our vendors is recommending 5000 to 6000 ppm as a normal operating range. Does this sound acceptable? I have been unable to find any information where baths were maintained at such high levels.
PCB mfg - Samutsakhon, Thailand
October 2, 2012
A. Hi Jason,
There's no absolute TOC (total organic carbon) tolerance of acid copper bath because it depends on what kinds of organic contamination. Some harmful organic contaminants even present in very small qty (<100 ppm) can spoil the bath while some harmless organic contaminants even above 1000 ppm may not affect plating performance significantly. Therefore, you need to base it on your own process (those can cause organic leach out into your acid copper bath such as dry film photoresist, plating additive by-product, etc.) to figure out TOC tolerance (you need to perform reliability test such as elongation/tensile strength, Hull cell, IST, etc., at different TOC levels and define TOC tolerance at which reliability performance will turn bad when TOC reach such tolerance level).
Regards,
David
David Shiu
- Singapore
October 21, 2012
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