John
Here is what we've seen:

1.  We have customers using both bright and matte tin baths, sulfuric acid based.  There doesn't seem to be an advantage to use one over the other.
2.  Thickness should be about 0.0003 (300µinches).  Any less will resist etchants, but low current density areas are safer at this thickness.
3.  Bar anodes versus nuggets is only a factor in cost; as nuggets are used completely, and bars leave you with sword-shaped pieces.
4.  Tin is a higher priced metal, but lead is removed from rinse waters and strippers.  A real waste treatment advantage.

Ed

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Ed Wright	Technical Support 
Oliver Sales Company 	Phone:  (214) 231-1522
13445 Floyd Circle 	Fax:  (214) 644-3585
Dallas, Texas  75243-1595 	E-mail:  [log in to unmask]
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From:  John Parsons[SMTP:[log in to unmask]]
Sent:  Monday, April 22, 1996 1:17 PM
To:  'IPC TechNet'
Subject:  Tin/Lead to Straight Tin Plating

From:	John Parsons
	Circuit Graphics Ltd.

We are currently plating tin/lead at 15amp/sqft over copper to act as an etch resist.  We are looking to replace the SnPb with straight Sn.
1. What are the pros and cons of bright tin vs matt tin?
2. What is the recommended plating thickness or current/area?
3. Pros and cons of bar anode vs ball and basket?

Thank you in advance for your help.