Back in the late 70's I worked for a company that had a captive PCB plant. Boards were plated with SnPb as the resist for etching. The plating was fairly heavy and had a rough surface. The boards were placed in a bath of hot peanut oil to level the solder surface and then cleaned. Solder mask was then applied with a silk screen followed by the ledgends with anohter silk screen.
Craig
--- In Homebrew_PCBs@yahoogroups.com, KeepIt SimpleStupid wrote:
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> I did it this way: I used a frying pan, peanut oil and something to keep the board off the bottom of the pan.
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> Solder dip and wet rag.
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> The oil residue was tough to remove. I would not use this method on critical circuits though.
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> ------------------------------
> On Fri, Jan 11, 2013 1:34 PM EST Rick Sparber wrote:
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> >I was playing around with some scrap pieces of circuit board I etched and
> >drilled in order to find a way to simulate the HASL (Hot Air Solder
> >Leveling) process. This process puts down a very thin coat of solder over
> >the copper. The solder protects the copper plus makes soldering in
> >components easier.
> >
> >
> >
> >I found that I could brush the board with flux. Then I built up a small bump
> >of solder on the ground plane. Using my soldering iron as a paint brush, I
> >dipped into the bump and then painted the copper. When done, I scrubbed the
> >board with alcohol. Worked great. I had no shorted paths.
> >
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