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topic 36730

White stains in RoHS electroless nickel plating, not in non-RoHS

A discussion started in 2005 but continuing through 2019

2005

Q. My company is doing electroless nickel plating on brass. However, we are facing white stain issue more than 10% of total production every day. The all chemical concentrations involve are controlled in the spec. The nickel bath was made up in the past 2 1/2 years. only top up nickel was done. I would like to know does this nickel solution make up life time can contribute to the issue?

Cheng Souk Ping
Plating company - Penang, Malaysia

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2005 A. Unless you are using one of the baths with highly specialized equipment to remove the breakdown products of the hypo, the normal amount of tank turnovers (100% replacement of the nickel ion = one tank turn over) is 4-20 with 8-12 being common. I am rather shocked that you can even plate with a 2.5 year old bath, even at 100% analysis. James Watts - Navarre, Florida 2005 A. When you say all chemical concentrations are in the spec what do you mean, basic chemicals? Do you analyze sodium orthophosphite, deposited phosphorous? Do you keep track of metal turnovers? How do you maintain pH and temperature? Is your work load fairly constant? Two and a half years is quite a long time. Undesirable by-products will keep forming regardless of care taken during the operation. Guillermo Marrufo Monterrey, NL, Mexico

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To minimize your searching efforts and to offer multiple viewpoints, we've combined some threads into the dialog you're viewing. Please forgive any resultant repetition or failures of chronological order.

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RoHS EN leaves white stain, non-RoHS doesn't

2005

Q. Having problem plating RoHS EN on 300 Series Stainless Steel 0.4 mm thick cover (Surface 90 mm X 70 mm). Result 80% with white stain. This only happen when I use RoHS EN. If I use non-RoHS EN, there's no white stain found on surface. Anyone can help. Thanks

Stewart [last name deleted for privacy by Editor]
Plater - Malaysia

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2005

Q. This white stain also is new for my chemist. My chemical supplier suspect is the surface too big. Previous we are plating disk clamp (40 mm diameter) and no problem all the time. Recently I try to shake the jig non-stop during EN bath. This only help me to reduce to 50% reject.

Stewart [returning]
Plater - Malaysia

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August 30, 2013

Q. Hi,

Our company produces Hard Disk Drive components and we have the electroless Nickel Plating process. However, our company has a problem about the white stain and black dot issue on the parts. Example: I run 3 jigs, only 1 jig has this reject. So, if this problem is due to EN bath, why don't 3 jigs have same reject?

Please advice what I can do to prevent this issue and find the root cause.

Regards,
Zana

Nur Zana Binti Japar
- Selangor, Malaysia

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September 20, 2013

Q. I would like to ask if dried oil on raw material will cause white marks after electroless Nickel process. If so, what are the causes of this occurrence?

Grace J.
- Cebu, Phils

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White stains in electroless nickel plating of pendants February 22, 2017 Q. We produce gold plated jewelry. Prior to Gold plating we perform the following process: - Polishing using a motor/lathe and buffing compound - Electrocleaning with a Buffing compound remover - Electrocleaning with al alkaline degrease (6v) - Nickel plating (3 v) - Gold plating (6 v) The problem is that we have some white stains in the borders of the pendants. I have modified almost each variables of the process but still have the stains. Rafael Araujo Metalsmith - Bogota, Colombia March 26, 2017 A. Hi Rafael, I am not sure I understand your question because the title mentions stains on nickel but your post mentions gold as well. Are the stains on the gold or do you see problems prior to Au plate? Blake Kneedler Feather Hollow Eng. Stockton, California April 19, 2017 Q. Hi Blake. We are having "white" stains in the edges of the jewels during the nickel plating. It is just in the edges. I do not know if the problem is in the previous electro-cleaning process or during the nickel bath. I have pics of these edges: Rafael Araujo [returning] - Bogota, Colombia June 2017 A. Hi Rafael. Your title indicated that you were "electroless nickel plating" these items, but based on the additional info you've provided, I'm leaning towards thinking that this was perhaps a language difficulty or typographical error and you meant "electrolytic nickel plating"? Although it's hard to photograph brightwork, so pictures can be hard to read, this looks and sounds like classic "burning" to me -- that is, the edges are receiving excessive current density, beyond that at which satisfactory plating can occur. More agitation and/or lower current (voltage) is the first thing I'd look at. Good luck. Regards, Ted Mooney, P.E. RET finishing.com Pine Beach, New Jersey We need "Aloha" now more than ever May 8, 2019 Q. I'm also facing the same problem, but my product is plastics-based, mainly ABS resin. The stains are detected at the high current area. Also the rejection only occurs on morning shift and none at night shift. We already tried a lot of troubleshooting such as reduced current, reduced temperature, increased brightener, extra wetting agent. We also did carbon treatment but still can't solve the problem. We detect it coming from our nickel bath because after we skipped plating for that tank the white stain didn't come. Can you give me a suggestion toward my situation. Mal Az - Johor, Malaysia May 2019 A. Hi Mal. Actually, I don't think your problem has much in common with white staining on RoHS-compatible electroless nickel plating on brass, so you could probably profit from searching the site with terms like "milky nickel -electroless", nickel whitewash -electroless", "burned nickel -electroless" to exclude electroless nickel from your reading and more easily read about the various possible causes of white stains in electrolytic nickel plating. The straight forward way to solve this problem seems to be to move your plater & foreman from night shift to morning shift because they are operating the plating line in different fashion than the day shift. It sounds to me like the day shift simply has the current set too high so the parts are burning, although you say you tried reducing it, but I suppose it's possible they are adding boric acid without dissolving it, or something like that. But again, the obvious answer is that your night shift plating team know how to fix it :-) Meanwhile please send pics to for posting here because there are so many different types of "white stains". Thanks and good luck. Regards, Ted Mooney, P.E. RET finishing.com Pine Beach, New Jersey We need "Aloha" now more than ever

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May 10, 2019

Q. Thank You Mr Ted for the fast response. I don't really think the problem comes form our foreman because our company applies rotating shifts and even though the same person during night shift operate in day shift they also faced the the same problem. At first, we also suspected that the chemical not dissolving probably because they supply powder chemical about one hour before morning shift start. For that we try to dissolve first outside before supplying to tank. For another information, the White stain is only at the edge and milky white in colour.

     

Mal AZ [returning]
- Johor, malaysia

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May 17, 2019

Q. Actually the white stain I want to show you is not shown by the cursor but the long line. I upload again the picture for your review.

Now we adjusting again the brightener also the additive. Seems like the stain improves but only for a moment. Now the white stain already come on night shift but not in morning shift. Seems everything become inverted. We try to do the same thing we did on both shifts -- exactly the same. Parts come in also, same amount but it's not working. Now we already fall into a grey area.

Mal Az [returning]
- Johor, Malaysia

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