Ways to minimize defects in electroplating

A. Hi Lweis,
Unfortunately there are components which cannot be "jigged once and done" because they will either cup so much dragout as to be non-feasible, or trap so much air as to be :-(

You may be confronted with the need to do one of three unpalatable things:
1. Turn the parts mid cycle (and maybe not just in one tank but in many tanks).
2. Design some sort of sparger system which can drive liquid into that cupped area and drive the air out (again this may need to be done in more than one tank).
3. Get permission to modify the parts, for example drilling a small hole for the air to escape if the needs of the component are such that the hole isn't problematical.

Luck & Regards,


Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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A. Hi Saran. The trite answer to your question is that you avoid defects by doing proper mechanical preparation, proper chemical pretreatment, proper electroplating, proper post-treatment, proper rinsing between each stage, proper drying, proper packaging, proper storage, and proper transportation :-)

But the fact that there are tens of thousands of postings just on this one site, just on the subject of plating defects, tells you that you can't get a useful answer to such a broad question -- it's like asking how to cure all disease or prevent all automobile accidents :-)

But there are entire library aisles of books on the subject, and if you give us the specifics of one particular defect, the readers will try to help you through it. Good luck!

Regards,

A. Hello Saran,

A good idea would be to go to a good company with wide experience in the field who consistently produce defect-free work without variation over millions of parts.

best wishes

A. Hi Saran. When you cite the problems of 'contact issues' AND 'airlocks' AND 'jig marks' it almost surely involves either poor design or poor maintenance of the plating racks. So you might start with inspection of the general condition of the plating racks, along with a quick study of the historical data related to these defects and the rack repair history & schedule, to try to ascertain whether it is a design issue or a maintenance issue. But don't overdo the 'study' part because "walking the line" is the key to most plating problems. Try to spend more time watching the plating line than analyzing it from your office :-)

'Undercoverage' is too vague for much useful comment. Instead, please name one part, one plating, and one defect, and list the process steps and we'll try to help :-)
Good luck!

Regards,

A. Saran, your question is very vague, but one golden rule in all electroplating is cleanliness. You must ensure that your components are as clean as possible before you start trying to plate them. You must also ensure that all your electroplating solutions and pretreatments are working to the manufacturer's specification. You must also ensure that your equipment is working properly -- this includes your rectifiers, agitation systems and filtration. For instance, "undercoverage" (I presume you mean the coating is too thin) can be caused by too low pH, low Nickel content in the bath, anode polarisation (resulting in poor dissolution and solution depletion of nickel ions), faulty rectifier, etc., etc. Pitting can be caused by too low pH, lack of surfactant, poor agitation etc. I suggest you speak to your chemical supply house and possibly ask them to provide a training course. Alternatively, contact the Institute of Materials Finishing in the UK - they provide distance learning courses in electroplating.