Sulfamate Nickel Plating
Sulfamate nickel is dull gray in appearance with a slight yellow or golden cast. Prodigy Surface Tech’s process is especially suitable for brazing, bonding, and soldering. The plating solution has no brighteners or levelers yielding a pure deposit with a matte finish. The low stress of the deposit provides superior ductility, elongation and machinability. It is particularly useful as a diffusion barrier for gold plating used in electronic and microwave devices. It also aids wetting for braze attachments and glass to metal seals.
While we supply Sulfamate Nickel exclusively for some customers, most use Sulfamate Nickel as an underplate for gold plating or other coatings.
Our Military and Aerospace customers use Sulfamate Nickel under gold plating to prevent iron and copper from diffusing to the surface during component attachment. At the appropriate thicknesses our nickel and gold plating can withstand temperatures above 400C. Prodigy Surface Tech’s plating can easily withstand the temperatures required for CuSil, Gold/Germanium and Gold/Tin brazing.
Even though Sulfamate Nickel plating is not bio-compatible, our Medical products customers use it as an underplate for gold plating to facilitate wire die-bond attachments found in sealed implantable devices.
The advantages of Sulfamate Nickel include purity, ductility and malleability. Sulfamate Nickel plating baths are stable and relatively easy to control. Compared to brightened nickel or electroless nickel where daily or even continuous additions are required, Sulfamate Nickel chemistry can be used for extended periods with very limited additions.
As long as function is critical and a dull matte appearance is acceptable, the main disadvantage of Sulfamate Nickel is a non-uniform deposit thickness. The deposit thickness is determined by current density or current distribution. The factors affecting current distribution include geometry of the parts, distance of the parts from the nickel anodes and placement of the parts on the plating rack. Sharp corners and prominences on the parts will plate thicker. Parts closer to the nickel anodes will plate thicker and parts on the edges of a plating run will plate thicker. Conversely, recessed areas or cavities on parts will plate thinner. Parts further from or shielded from the nickel anodes will plate thinner and parts located in the middle of a plating run will plate thinner. Relative uniformity can be improved by adding thieves to draw current away from the parts. Shields can be used to block current from high current areas and auxillary anodes can be used to increase current in recessed areas or cavities.
To maintain the quality required for NADCAP certification and AS9100 registration we have a crew dedicated to plating bath maintenance. Our Sulfamate Nickel baths are analyzed, adjusted and re-analyzed multiple times per week. Our frequent periodic maintenance includes electrolytic purification for trace contaminants; removal, cleaning and replenishing of nickel anodes; particulate filter replacement and transfer filtration with carbon treatment.
AMS-QQ-N-290: These products have been used typically for electrodeposited nickel plating on steel, copper and copper alloys, and zinc and zinc alloys, but usage is not limited to such applications.
MIL-P-27418: This specification covers the processes and requirements for soft nickel plating.
AMS 2424: This specification covers the requirements for electrodeposited low-stressed nickel.
AMS 2403: This specification covers the requirements for electroplated nickel coatings applied to metal products for engineering applications, for example, for use as a buildup for mismachined or worn parts, for electronic applications, including as underplates in contacts or interconnections, and in certain joining applications.
ASTM B689: This specification covers the requirements for electroplated nickel coatings applied to metal products for engineering applications, for example, for use as a buildup for mismachined or worn parts, for electronic applications, including as underplates in contacts or interconnections, and in certain joining applications.