Homebrew PCBs

In a message dated 7/30/2004 6:49:38 AM Central Standard Time, 
eemikez@... writes:
It wasn't clear from your post if you were talking about tinning the 
copper traces or tinning the thruholes. For traces to be tinned, the 
solution needs to be hot, otherwise it takes very long time. Mike
Yes, there must FIRST be good copper PTH "IN there"!  Then the PC-pattern is 
"tin-plated".  The tin-plate also plates INSIDE the holes, of course!  The 
etchant then will attack only the bare copper, NOT the tin.  After all undesired 
copper is gone, I understand the boards are heated under IR lamps, etc, to 
"reflow" the tin-plate, leaving a nice shiny "solder plating" where you have no 
green "solder mask" (a kind of high-q. epoxy-paint).  Jan R.


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