Scott: I�m not familiar with some of the things you�re talking about, but let me: * Agree with Russ & Peter regarding immersion silver. * Give some snips of information on the substrate side of things that might help you to tie this together. � FR-1 is cheaper than FR-4. In fact no substrate material is cheaper than FR-1. � FR-1 is a phenolic / kraft paper laminate. (FR-4 is a resin/glass laminate). � FR-1 has no plated through holes. It has plated trace on a single side. (FR-4 can have plated through holes and more than one layer). � FR-1 is a punch grade material. Over 50% of the world market is punch grade. � Part of the price you pay for being able to punch is tg. FR-1 has a tg of 90�C. So, it�ll sag during wave soldering, but punch grade ain�t at 50% �cause no one can work with it � Following on with that, FR-1 will blister on a 260�C solder pot after 80 seconds (FR-4 will last for a coupla minutes. � Most people size the through holes on single sided boards to provide support of the component leads. � Most electrical properties of FR-1 are not superior to other substrates.
Good luck Dave F
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