Chemical Attack of Nickel Plating
Chemical Attack of Nickel Plating
(OP)
We are considering making a protective cover for a transducer electronics out of Polyphenyl Sulfide (PPS) that would require EMI shielding and a decorative finish. Nickel plating, specifically electroless, was proposed to do this. Additionally this cover is in an area where leaks or drips of chemicals, organic solvents from 2pH - 13pH, could come in contact (incidental) with the plated finish and we are concerned about the part maintaining its appearance. Would EN be suitable againast chemical attack? What are the chemicals that could attack or discolor EN?





RE: Chemical Attack of Nickel Plating
A 4-page table “Corrosion Resistance of Electroless Nickel” is included in EN properties at http://www.stapletontech.com/pdf_files/State_of_EN_Scie...
“Properties and Applications of Electroless Nickel” from NiDI mentions:
High-phosphorus EN is more corrosion resistant at acidic or neutral pH, while low-P EN in more resistant at high pH. EN is superior to 316 SS in some chemical industry applications. Further, EN provides corrosion and wear resistance to moulds used for plastic and rubber parts. A minimum of 50 microns of high-P EN is used for optimal corrosion resistance. Also,
“Plating of plastic housings for EMI shielding requires many large areas to be covered. Electroless nickel is used in many cases to provide protection against corrosion and tarnishing for electroless copper, which is deposited directly on the plastic housings. Nickel thickness is typically 0.25 to 0.50 micron.”
http://www.nidi.org/multimedia/technical_support/techni...
Elsewhere, it has been claimed that the electroless copper and electroless nickel combination “has the best shielding characteristics of any of the coatings available.” http://pfonline.com/articles/129901.html
Due to your corrosive environment, I suggest using 25 microns of a mid- or high-phos. EN, plus passivation in a warm, 0.2% chromic acid solution and/or application of an anti-tarnish sealant: http://pfonline.com/articles/clinics/0402cl%5Fplate5.ht...