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stain between the electroless nickel substrate and the copper strike plating on plastic

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 sulphuric 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

Dear Steve, Maintain the same concentration of sulphuric acid in second water rinse before copper strike as in strike copper Varun

Varun Kumar
- India

This has a direct bearing on your problem. Check out "Who Really Cares About the Surface Preparation Requirements for the Sucessful 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

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