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HELP! Plating issue on chassis

KA Stillings

#11372

HELP! Plating issue on chassis | 21 May, 1999

I normally handle the soldering issues for this facility but a question was asked of me -- What the H@## is this stuff and what is causing it? Was wondering of I could get some input from any Guru on plating issues. Need info ASAP!!!!!!!!!!!!!!!!!!!! Here's the problem: have a zinc plated chassis with a base of stainless steel and the handle is brass plated with nickel. We have finger prints that can't be removed and a wash-like streaking across the surface of the material. This stuff "oxidizes" just sitting in a room and transportation overseas only accelerates the process. Desiccant agents don't even work. Testing found iron oxidation randomly spaced along some finger print patterns. Unsuccessful attempts were made to lift the deposits using tape. Samples were then cut for testing evaluation. SEM/EDS analysis showed trace elements of zinc, low levels of chrome, oxygen, aluminum, calcuim chloride, phosphorus, carbon, chlorine, iron, potassium, silicon, and sulfur. Higher levels of "corrosive" chlorine were found in fingerprint areas with small definitive locations of very high calcium. Initiation of the corrosion has been determined to be at the plating.

Is it possible the plating vendor is using a washing agent after plating that contains the corrosives mentioned above and over time these elements are leaching out and corroding the plating? Can someone shed some light in this issue? We've been using the plating for 6 years and this is a new occurrence.

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JohnW

#11373

Re: HELP! Plating issue on chassis | 21 May, 1999

| I normally handle the soldering issues for this facility but a question was asked of me -- What the H@## is this stuff and what is causing it? Was wondering of I could get some input from any Guru on plating issues. Need info ASAP!!!!!!!!!!!!!!!!!!!! Here's the problem: have a zinc plated chassis with a base of stainless steel and the handle is brass plated with nickel. We have finger prints that can't be removed and a wash-like streaking across the surface of the material. This stuff "oxidizes" just sitting in a room and transportation overseas only accelerates the process. Desiccant agents don't even work. | Testing found iron oxidation randomly spaced along some finger print patterns. Unsuccessful attempts were made to lift the deposits using tape. Samples were then cut for testing evaluation. SEM/EDS analysis showed trace elements of zinc, low levels of chrome, oxygen, aluminum, calcuim chloride, phosphorus, carbon, chlorine, iron, potassium, silicon, and sulfur. Higher levels of "corrosive" chlorine were found in fingerprint areas with small definitive locations of very high calcium. Initiation of the corrosion has been determined to be at the plating. | | Is it possible the plating vendor is using a washing agent after plating that contains the corrosives mentioned above and over time these elements are leaching out and corroding the plating? Can someone shed some light in this issue? We've been using the plating for 6 years and this is a new occurrence. | KA..??that your name or u just being formal??

anyhoo seen this before on chassis for some end product's I used to be product eng for..till I escaped to the wonderfull world of Processes..ha liberation!!!! oh yeah the point.. sound's like it's plating run off problems. when the plating is applied the chassis is hung up to dry usually after it's hit with an air knife to run off the excess plaiting. Sound's like your plating house has messed up and allowed theangle of run off to be too shallow or there has been contamination in the tank. anyway's chances are you wont get it off at all..all you can do is send em back and get them stripped and replated.oh and bill the the fab house big time for your lost production..they should know better. There are some surface stuff u can remove with a rubber of all thing's..( that's an eraser in case anyone has a warped mind..or is it me for thinking folk's have warped mind's.?) anyway's go back to the fab house and kick up hell..

JohnW

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