Summary for stain between electroless nickel and copper strike Discussion
The thread on stain between the electroless nickel substrate and the copper strike plating on plastic centers on a striated, ridging-like appearance forming after electroless nickel and before an acidic copper strike. Steve Jennings says the line has two rinses and spends 20 seconds in an acidic copper pre-dip, but he still sees the defect and wonders whether sulfuric acid in the last bath should neutralize the surface enough. Varun Kumar replies that the sulfuric acid concentration in the second water rinse should be maintained the same as in the strike copper, implying the rinse chemistry is directly tied to the problem. A second answer adds that the issue has a direct bearing on surface preparation and points Steve to Brad Durkin’s article, “Who Really Cares About the Surface Preparation Requirements for the Successful Application of Electroless Nickel?” in Products Finishing, which reportedly gives a step-by-step method for solving this kind of issue.
Q. I am having troubles with a stain or striated appearance between my electroless Ni substrate and my copper strike.
the appearance is almost that of a ridging effect associated with an acid copper,I have 2 rinses between the E/Ni and Cu strike and the latter being acidic,i understand that the alkalinity will affect the surface but I thought that at least 1 litre of sulfuric acid in the last bath (600 lt cap)would neutralise the surface enough to avoid this problem.
Does anyone have any other suggestions or methods that they use to overcome this problem.The line is automated and sits in the acidic copper pre dip for 20 seconds. Thank you
Steve Jennings
– Australia
2000
A. Dear Steve, Maintain the same concentration of sulfuric acid in second water rinse before copper strike as in strike copper Varun
Varun Kumar
– India
2000
A. This has a direct bearing on your problem. Check out “Who Really Cares About the Surface Preparation Requirements for the Successful Application of Electroless Nickel?” by Brad Durkin of Macdermid in Products Finishing. It also gives a step by step method for solving your kind of problem.
James Totter, CEF
– Tallahassee, Florida
2000