Tin/Nickel has been around for along time. You're absolutely right. The conductor overhang can be such as to produce bad slivers that can easily create shorts. A good way to overcome that issue is to tightly control the plated thickness to an extreme minimal. (Generally this must be negotiated with the customer up front due to customary Nickel requirements.) If the deposit thickness is <250 u inches, (50-100 preferred, 100-200 with fairly good results) you can generally cleanly etch the circuitry with the overhang at a minimal or even removed during the etching process. If a mild scrub is required, at that thickness you can eliminate the overhang issue(s). Tin/Nickel, however, has really only focused on niche markets such as high temp boards (BIB)and a few others. It really never was widely accepted due to similar issues that you listed. The tin surface is more user friendly. Surface Tin plating is something that many large volume shops are doing that has been successful. (No solderstrip required. HASL readily takes to the solderable surfaces with tin over copper.) I'm waiting to see what their comments are. ______________________________ Reply Separator _________________________________ Subject: Re: Solderability of Electrolytic Tin Plating Author: [log in to unmask] at SMTPLINK-HADCO Date: 9/27/95 9:34 PM In a previous life I worked for a place that made thousands of tin boards. The customer (Texas Instruments) specified nickel as a migration barrier between the copper and tin. There is no reason you can't use bright acid tin as a surface finish. The one caveat we encountered was that using tin nickel as an etch resist tended to give very sharp edges to the lines where the etchant undercuts the nickel. Operators can cut their hands and if you overetch and get slivers they are like little razors. --------------------------------------------- While cruising the Internet, be sure to visit our home page at http://www.automata.com --------------------------------------------- On Wed, 27 Sep 1995 [log in to unmask] wrote: > Does anyone have any experience soldering surface mount devices to > Electrolytic Tin plating as opposed to Tin/Lead reflow or HAL? We have a > customer that is interested in this but wants us to ensure that they'll be > able to solder the boards. They are using a BTU convection oven for > reflowing the boards after assembly. Thanks in advance for any > correspondence. > >