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Adhesion problem plating tin onto Aluminium castings

1998

We have a problem with adhesion of tin deposits of 25 microns on aluminium castings. Our spec is to plate the tin directly with no pre-plate over the zincate deposit as the product must be crimped after plating.

Any comments on preparation other than the standard procedures in the data sheets and books & magazines?

Bob Lynch
plating company - Sydney, Australia

If you are going into an acid tin bath I don't see how you can avoid at least a five minute dull nickel pre plate after the zincate. The nickel would be a watts type bath, pH around 5. You should go in live entry on high power to prevent blistering in the low current areas. This shouldn't cause any problems with crimping if the time in the nickel is kept between 5 and ten minutes. Going into an acid tin would dissolve the zincate layer almost immediately without this pre plate.

Simon Lee
electroplating shop - Auckland
1998

dear bob
try the plating in alkaline tin bath.

sunil singh
- Bangalore, India
January 9, 2010

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