On Jan 27, 2009, at 8:13 AM, Peter wrote:

> most non-smd large series boards (phenolic, low resolution) are
> made in a totally different way from FR4 boards. Holes are punched,  
> not drilled,
> boards are punched out, not router cut, copper masking is printed on  
> not
> photoexposed, and so on.

I believe there is also a significant set of boards made where the  
"resist" is actually the tin/lead plate, and the etchant is some  
ammonia based concoction.  (I'm not sure what RHoS has done to this  
process.)  Naturally, a plated resist makes for the possibility of  
very fine lines...

BillW

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