plating, anodizing, & finishing Q&As since 1989
Nickel peel-off on Siclanic (Cu/Ni/Mg/Si alloy)
April 16, 2012
Q. We have been experiencing Nickel is failing adhesion on a special base material called Siclanic (Copper alloy containing Ni, Mg, and Silica). The process being used is as below:
1. Alkaline Cathodic Cleaning
3. 15% Sulfuric Acid Dip
5. Dry Acid Salt treatment (fluoride containing)
7. Sulfamate Nickel
9. Silver plating (selective)
11. Gold Plating (selective)
The failures on more predominant on the area where the final finish is Gold.
There were various trials carried out using different conc., temp. and CD in cleaner also a combination of soak followed cathodic.
Also applied cathodic current in dry acid salt and additional Nickel strike (wood's Nickel) prior to sulfamate Nickel.
Kindly suggest suitable treatment to over come the peeling off of Nickel from base material.
Electroplating - Sales and support - Bangalore, Karnataka, India
A. You need a strike nickel prior to the sulfamate nickel. By strike I don't mean
WOOD's^WATTS nickel but a solution based on Nickel chloride and Hydrochloric acid.
Ed. note: I think there was a typo there, Sara. I think you "don't mean Watts" :-)
A. You do not give the composition of your Siclanic, but I would suggest you need to ensure the surface is silica free and this is best done by a pretreatment in fluoboric acid acid/ hydrogen peroxide dip; use about 10% acid and 5-10% peroxide, but be very careful - this stuff is very aggressive and hazardous. However, you may need to increase the acid strength, depending on the silica content. I would then plate it in a copper fluoborate bath and then plate with nickel sulphamate. If possible try to avoid rinsing after the hydrofluoric acid treatment, but if that is not possible, use a dilute HBF4 rinse. I also suggest you develop the process in the lab first.
R&D practical scientist
Chesham, Bucks, UK