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topic 17284

How to plate the bright nickel over the brass parts


2002

How to plate bright nickel over the brass parts? We have soak cleaner, electrocleaner, power acid (sulfuric acid 10% by vol ), Wood nickel strike and bright nickel. What is the plating cycle to plate nickel over the brass parts?

popat patel
Popat Patel
    Beacon Park Finishing LLC - Roseville, Michigan


2002

Brass used to manufacture parts usually contains lead as a machining aid. Sulfuric acid and hydrochloric acid form insoluble compounds with lead in the surface of the brass resulting in a star dusting type of appearance in the bright nickel. One cycle that works well is mild alkaline clean, rinse acid dip in either sulfamic acid 4-5 oz/gal., or fluoboric acid, 6-10% by vol. Rinse copper strike (either cyanide or fluoboric acid copper) 1-2 minutes, rinse, acid dip in sulfamic acid 4 oz/gal, rinse, and nickel plate.

Note: cyanide copper strike will accumulate lead in the solution. Small additions of sodium sulfide will precipitate the lead to be picked up in the filter. Do not add a large excess of sulfide.

Either process will result in a clear bright finish.

don baudrand
Don Baudrand
Consultant - Poulsbo, Washington

(Don is co-author of the
book "Plating on Plastics")


2002

There seems to be no problem with the process that you are following. The woods nickel strike also may not be required, but I would recommend using a dilute HCl predip after the alkaline cleaners instead of the H2SO4 if brass is the substrate.

Khozem Vahaanwala
Khozem Vahaanwala
Saify Ind supporting advertiser
Bangalore, Karnataka, India

saify logo


2002

Hi Popat Patel,

Your pretreatment cycle is perfect. You don't need a nickel strike. Sulphuric acid should work well and acid concentration also is good. If your plating the parts with watts nickel which has both nickel sulphate and nickel chloride you can use either sulphuric or hydrochloric acid for activation. Both works equally well. If you want to improve your cleaning you can introduce solvent cleaner preferably with ultrasonic effect. If the brass parts are tarnished it can be dipped in 5% sodium cyanide solution.( optional, not a must)

Venkat Raja
- Kitchener, Ontario, Canada


2002

I would agree with Don, but lean towards the fluoroboric acid option. Note: this is an immersion dip not electrolytic.

Gene Packman
process supplier - Great Neck, New York


Cu underplating needed for Ni plating on brass?

October 8, 2018

Q. For a brass terminal (terminal A) in an electrical connector for an automotive sensor application we use 1-3 µm Ni plating. A similar brass terminal (terminal B) has 2.5-5.0 µm Ni over 0.75-2.50 µm Cu preplating.

1) What could be the reason for using a Cu preplating under Ni?
2) What would be the risk (if any) if I would increase the Ni thickness of terminal A to 2.5-5 µm without a Cu underplating?

Jaap Hoftijzer
Design Engineer - Hengelo, The Netherlands


October 2018

A. Hi Jaap. I don't think copper plating is required. My own theory of why it sometimes seems worthwhile is that when you have rather thin plating you are liable to get a pin-hole, but the chance of having a pinhole at the same spot in two different plating layers is small. So the chance of exposed brass may be smaller with the copper plating.

If 2.5-5 µm of nickel is free of pinholes, as determined from salt spray testing, I think it will offer better protection than a layer of copper followed by a thinner layer of nickel.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


October 24, 2018

Q. Hi Ted,

Thank you very much for your reply.
Just to confirm. The Cu underplating would be intended for corrosion protection not to improve adhesion of the Ni layer? Is there a risk of adhesion problems (or flaking) with a 2.5-5.0 µm Ni layer?

Best regards,

Jaap Hoftijzer [returning]
Sensata Technologies - Hengelo, The Netherlands


October 2018

A. Hi Jaap. I can only give you my understanding, not ultimate non-challengeable fact :-)

If the brass is leaded, it requires fluoride-bearing acids; and in that case most platers prefer the next step to be copper fluoborate plating. But assuming that the brass is not leaded, nickel plating adheres well.

The idea of the forum is that if a reader disagrees they will hopefully chime in :-)

Good luck.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


October 24, 2018

Q. Hi Ted,

Thanks again for your reply.
The terminal supplier is using C2600 brass which has a Pb content <0.05%. Would that be considered a brass type without Pb for plating purposes?

Best regards,

Jaap Hoftijzer

Jaap Hoftijzer [returning]
Sensata Technologies - Hengelo, The Netherlands


October 2018

A. Hi again. My understanding is that per recent California legislation, <0.20% is considered lead-free brass. I would certainly not expect <0.05% to require special processing due to lead content.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



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