In a message dated 06/27/2000 10:08:37 AM Central Daylight Time, [log in to unmask] writes: << <Rod Serling voice over> That must be of the few board related experiences you have missed, Steve. ;-) I believe what you are referring to is what I call "via plugging", which we have done at our fabrication suppliers. This is a thermal epoxy applied after HASL by silkscreening thermal epoxy soldermask. We normally do this only on the "solder" side of the panel. Our vendors create the necessary artwork to do this from the drill chart, and plug only the vias (typically 0.010" dia PTH's with 0.025" pads). This is done because the "tenting" of the via with LPI mask would not be reliable, and because the LPI "plugs" might rupture in the thermal excursion of HASL, entrapping HASL flux or other nasty stuff. The cost is just a few dollars per panel, so on a unit basis, should be slight. <back to "normal" comm mode> regards, Jerry Cupples Interphase Corporation Dallas, TX USA >> Hi Jerry and all, I didn't explain things enough. This board uses dry-film solder mask, and has only the vias open that are used for ICT testing. We've been building these boards in the past by masking the vias off just prior to wave solder to prevent the cleaning issues that would happen because some of the vias are beneath the LCCC's. This has been a pain in the butt, but not so bad because there weren't that many vias to worry about. But now they want to expand ICT coverage, and instead of selectively going into the soldermask layer of the gerber and opening the additional test vias that they need, they want to do a global change and relieve ALL vias from the soldermask! There's a number of different assemblies that they want to do this to, and I was told that it would be too much work to edit each and every gerber to accomodate the expanded test coverage on each assembly. I told them that I had a real concern with the cleaning issues that will arise from this, as well as being able to get good via fill. I've had trouble in the past getting good via fill during wave solder on boards using a dry film solder mask. I've read a few posts over the past months that a half-filled via is worse than no-fill or full-fill. So what I was asking was; can the fab vendor fill the vias during the HASL process? If they can, is it expensive? -Steve Gregory- ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################