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Matte tin - what is the criteria appearance or thickness which determines coverage

2003

Hi,

We recently used matte-tin plating on our filters - according to ASTM B545. with a .0003 inch thickness. The filters have the matted dull look but some areas appear shiny after brushing during the cleaning process. I wanted to know if this means the matte-tin is no longer present in these areas. Our customer wanted to reject the parts saying there is not sufficient coverage because of the loss of the matted look. I'm trying to determine what is the criteria for matte-tin - the dull look or thickness?

Larine Harper
- Salisbury, Maryland, USA

I am also interested in the answer to this question.

Ramon Dehoyos
Military - Sykesville Maryland
2005

I believe the reason for specifying matte tin is so that organic brighteners are not used in the plating solution which might interfere with subsequent soldering.

The spec reads in part: "The appearance shall be uniform throughout, insofar as the basis metal will permit". And apparently it was so before the burnishing.

The fact that a surface burnishes up when burnished should be no surprise or, to my mind, any cause for rejection if the tin was deposited from a matte tin bath and is still the proper thickness, But it is necessary to check the plating thickness in that area and make sure it still complies. Just an opinion.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2005