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letter 42907

Brown stains on electroless nickel plated materials



A discussion started in 2006 & continuing through 2017

(2006)

Q. Our company experiences a significant increase of material defects due to brown stain. We always thought that this is caused by high conductivity on water rinses. We maintain the conductivity of our rinses to less than 1 uS/cm. Still brown stain persists. Would there be any other causes of this problem?
Thanks.

JM Puguan
Plating company - Cavite, Philippines


(2006)

A. Suggest to:

1. Check if Ni bath metallic contamination such as Cu is high. If so, run dummy at 2-5 ASF for several hours;
2. Measure nickel thickness (too low?) and porosity (too high?)
3. Verify whether plating parts are completely dried after plating;
4. Storage condition such as temp and relative humidity is important also


David Shiu
- Singapore


(2006)

A. Brown spots causes are existence of Fe3+; mechanical contaminations; overdosage of brightener/leveling agent; or pH value is too high. Best regards,

Ada Garber
- Istanbul


(2006)

Q. We are experiencing a problem with brown staining/ tarnishing appearing a few hours later on radio components that we are electroless nickel plating . The components are machined from solid aluminium billets and are electroless coated for one hour using a high phosphorous solution. After plating they are rinsed in de-ionised water and then blown with compressed air to clear any blind holes , corners, etc.Does anyone have any advise for us ? We cannot use any de - watering or oil based coatings as some components are then powder coated afterwards .

MARK WRIGHT
electroplating - DURBAN, KZN, SOUTH AFRICA


(2006)

A. Hello Mark,
Can you pinpoint if the staining is coming from blind holes or corners on the part? If so, an air agitated DI rinse may be in order. I like to use a 2 to 3 counterflow rinse system with the last rinse being air agitated. As you probably know the last DI rinse should be the cleanest. Good Luck!

Mark Baker
Process Engineer - Syracuse, New York


(2006)

A. I THINK FINAL DI WATER RINSE SHOULD BE HOT TEMP. 60-70 °C.
IMMERSION TIME 2 TO 3 minutes WITH AIR AGITATION.
THEN DRY HOT AIR, OIL-FREE

ajay raina
Ajay Raina
Ludhiana, Punjab, India


(2006)

A. Dear,

The quality of rinse water can cause brown stains. First make sure you use DM water for rinse. Second check silicate in rinse water. There are chemicals and color disk to check silicate in water. If you exceed 1 ppm of silicate, you are likely to get stains. A regeneration of DM plant will bring down silicate contamination. Check silicate and try. Best wishes.

Kaushik Magiawala
plating shop employee - Gandhinagar, India


August 11, 2009

Q. We are having problem regarding rust in our plating on Fe material, we already increased our concentration on acids and plating thickness but still rust exists. What are the countermeasures do you suggest we should implement? Thank you.

Mie Leoveras
Plating Company - Cavite, Philippines


August 12, 2009

Hi, Mie. Are you from the same plating company in Cavite as JM Puguan, and is this a continuation of the same question? Several suggestions were already made. Can you frame your question in terms of those previous suggestions rather than asking everyone to re-post their answers again? Thanks!

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


March 28, 2013

Q. Hi..
Actually my company produces the product from electroless nickel plating.
Currently my company also has same problem about the stain issue. Until now we also cannot solve this problem. We already do adjustment at rinsing tank, but still have stains. Can you advice me of the solution to avoid this problem.

Nur Zana
- Selangor, Malaysia


June 3, 2013

Hi Nur.

As you see, nobody replied to you in over 2 months. People are not unsympathetic to your problem, but they already took the time to think through an issue and offer their suggestions, and then you post that you have exactly the "same problem" and ask what to do? Well, "same problem" = same answer :-)

You really can't expect David and Ada and the other responders to have anything to say until you acknowledge their suggestions and tell them your reactions and your findings regarding those suggestions. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



May 31, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. We have a bright Nickel Solution about 1500 gal and we are getting Brown Stains after plating and rinses (triple rinse).
The concentrations in the tank are:
Nickel (metal)= 9.8 oz/gal
Nickel Chloride= 13.15 oz/gal
Nickel Sulfate= 29 oz/gal.
Boric Acid= 6.5 oz/gal.

Any clue about these brown stains or any suggestion? Thanks.

E. Vargas
- Miami, Florida, USA


June 2, 2013

A. Hi E. Although your problem is with bright nickel plating, we appended your inquiry to a thread about brown stains in electroless nickel plating because I think the causes are probably the same. Too much iron in the bath and/or the pH too high may be causing the rusting.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


June 3, 2013

Q. Thanks for the suggestion. I just received the results for the lab of metals contamination. These are the values:

Fe= 2.4 ppm
Cu= 0 ppm
Zn= 3.9 ppm
Ca= 237 ppm
Mg= 42 ppm

So once again... Any suggestion ...

Thanks,

E. Vargas
- Miami, Florida, USA


June 5, 2013

A. Hi.
Usually occurs when plating steel parts in a barrel. After cyanide copper strike then bright nickel plating the parts, the problem was solved.

SK Cheah
- Penang, Malaysia



Mating section:
42907-1a
Other affected area:
42907-1b
February 20, 2017

Q. Hello,

The company I work for makes Ultem parts and are sent to an outside process to plate with Copper first then Nickel. The parts return with black/brown marks as mentioned in the trend. My concern is whether the bonding material we use (Dichloromethane) is causing the problem or is it more related to the previous answers? Two parts are bonded and most of the time the brown/black spots are around the crack where they are mated.

Hugo Martinez
- Santa Maria, California, USA


March 26, 2017

A. Hi Hugo,
It is common to have surface defects around assembly joints. The primary cause is usually contamination caused by entrapped liquids. Very thorough dragout, spray rinsing, triple cascade, final IPA, even the drying process all must be optimized. Batch size might be too big or too many parts might be on one rack. Poor rack design could be a factor because you need to be able to spray and rinse effectively. Also, consider the direction of the parts on the rack to optimize dragout.

blake kneedler
Blake Kneedler
Feather Hollow Eng.
Stockton, California



April 6, 2017

thumbs up signBlake Kneedler,

Thank you for your response. Our source started using a different process that involves dehydration. I'm not sure after what step they do the dehydration, but it seems to work. Our parts are finally looking better. Thank you.

Hugo Martinez [returning]
- Santa Maria, California, USA



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