As the industry heads towards a point where surface mount technology and dense circuit topologies are the norm it becomes imperative to revisit the issue of to tent or not to tent. With liquid photoimageable solder masks still being an unreliable means of providing a uniformly conformal coating over copper features, is dry film the answer? Have strides been made of late in this technology which allay the inherent problems of process control, media thickness, and contamination due to oily residue buildup and its subsequent promise of sundry other problems such as delimitation? Has MIL SPEC 2000 (is rev C out yet?) acquiesced in the use of either the dry film or lpi tenting of vias as an acceptable practice? I have seen boards produced in the orient with dry film thicknesses as small as 50 microns. Are these available in the US or is their use shunned as being too thin? The suppliers I have spoken with cite minimum thicknesses in the >1 mil range. This lays bare other problems, such as potential tomb stoning while providing the opposite benefit of creating a solder well around SMT lands. The latter stated benefit is of dubious value if paste stencils and application coupled with fine tuned temperature control bogs down production and outweighs the reliability bonus, if any. It is a confusing issue and all the literature I can find seems to be horribly out of date (the latest being an excerpt from PC FAB magazine dated 1991. I am reasonably certain things have progressed since then, but where is the data? If you have any insights into this well masked dilemma, I for one could stand the relief. [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************