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Watermarks (line) on plated components

We have Electroless Ni-Cu-Ni-Cr plating on ABS plastics, but recently we are facing the watermark (Lines) on plated components. Almost 99% of the plated area is having no problem with it.
Earlier we found this problem was because of increased conductivity of DM water, hence we maintained it below the suggested range i.e. 2 micro siemens. The issue is then solved.
since then we are maintaining the DM water conductivity below 2 microS But now after a year the problem is raised again. So what could be the reason and please tell the solution.
The Watermarks occurred only on the Uppermost (1 feet) component of every jig.
It is Visible after Cu plating.

Manisha Rathi
Engineer - Gurgaon, India
March 5, 2008

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Hi There,

Could you please let us know whether you are running the line at a single stage or after Electroless Nickel you change the jigs , if it is please have a good sponge wash for the components before going ahead to Acid copper, also air agitation in all the rinses would also be preferable.

Regards,

Praveen Kumar
plating process supplier
Mumbai, India
March 7, 2008

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Manisha, ensure that during jigging after electroless nickel plating,components should not dry and gloves used for jigging should not be sticky.
Also, maintain the acid dip concentration before acid copper plating is within range (i.e. 10%) and all water rinses should be clean(free of turbidity).
Maintain hypo (Reducer) content in El. nickel bath within range.

Manoj Kushwaha
plating & painting - Rampur, India
January 7, 2011