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Acidity in activator bath for electroless nickel plating

I am an engineer from a PCB shop in China; I have encountered a problem of controlling the acidity of the activator bath for EN plating.

We are using Pd catalyst and the recommended range is 80 - 200 ml/L, but now we have raise to ~270 ml/L and looks like it will require a further raise.
There are 2 sources of acid:
1. from Pd replenish during normal operation, acidity of this is 1200 ml/L.
2. drag-in from acid pre-dip, acidity of pre-dip 1000 ml/L

Kenneth Chen
PCB shop engineer - Suzhou, China
March 16, 2011

I think you need to clarify your post, since a concentration of 1200 ml/L is impossible in normal usage.

James Totter, CEF
- Tallahassee, Florida

Hi Kenneth,

Pd catalyst bath acidity shouldn't go up if predip acidity is lower than catalyst bath. When you replenish Pd into catalyst bath, don't replenish Pd and acid together. Most ENIG suppliers provide Pd catalyst solution without acid inside (or contains only very small amount acid) and let user to add generic acid (either H2SO4 or HCl) separately if acid content in catalyst bath drop too low.

Regards,
David

David Shiu
- Singapore

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