The authoritative public forum
  for Metal Finishing since 1989
-----

Skip plating and rough plating

Our medium phosphorous EN bath in the first 3 MTO, it often skip plating at the down side edge of the parts( up side edge are all OK), sometimes the down side edge of the part plated EN, but the Ni crystal is rough, normally after 3 MTO, there is no such problem, need your help! Thanks!

Liang Zedong
- Singapore
2002

---

Dear Mr Liang,

What I understood that your bath is not homogeneous so may you reconsider the agitation system efficiency it could play important role in heat distribution so the upper part[high temperature layers] and all ingredient are dissolved so its OK but at the bottom of the bath temp. Is not OK AND some undissolved salts co-deposit with EN so it has a crystals in appearance. Hope I was understanding your problem.

RAAFAT ALBENDARY
plastics electroplating - Cairo, Egypt
2002

---

Try pre-leaching the filter in dilute sulfuric overnight before putting it in the new bath. Also try adjusting the solution flow -sometimes less is better, or vise-versa. I've seen this too and it seems some brands of EN are prone to this more than others.

Kevin Keating
- Rochester, New York
2002

You seem to have an imbalance of complexants, catalysts and inhibitors from the beginning. Skip or step plating is sometimes due to an abnormal high plate speed (too high catalyst and complexors or too low inhibitor). Sometimes and in some chemistries, orthophosphite can slow plate speed. For some reason, the accumulation of ortho after 3MTOs is acting in such way in your bath, that slows the speed and the problem seems to dissappear. You absolutely have to get a professional review and advise about your operation. An opinion through the web is not the answer to your problem.

Guillermo Marrufo
Monterrey, NL, Mexico
2002