Folks, I talked with several kind and knowledgeable folks since Friday. It is obvious to me, as it must be to you, I have much to learn about CAF and its direction. I have condensed my replies into the following and am now ready to take my medecine or just get shot at though hopefully missed: xxxxxxxxx, First let me thank you for inviting me into your worlds. That makes you a big part of mine as I do understand the need for effective reliability testing and appropriate test methods. You, Werner, and some other fine folks have drilled that into me. I do understand your concern with various test methods being considered. However, you understand mine as considering why the stated phenomenon should be a concern. I clearly understand electrical shorting, whether at/in hole walls or through innerlaminar planes and MLB structures, is not desirable, to say the least. My biggest problems relate to: 1) Drilling holes as small as those spaced on 10.5 mil centers and who does that or would want to with other circuit alternatives available. Even at 25 mil spacing, these would become buried vias obviously not found on the surface especially a BGA pattern as there are so many problems associated there with this issue. However, I do understand possible use in the BGA device substrates themselves. 2) I've never doubted there could be hollow glass fibers. I've always believed the phenomenon to be very rare as 7 and 9 micron diameter filaments, drawn from a molten silica bath, almost makes that impossible. Also, these glass fibers should be drawn under extremely well managed vacuum processes for Class 3, and other, applications where cost is not the primary issue though extreme reliability, under extreme operations, is. 3) Hole "drilling" for such small diameter holes as mentioned in 1, above, should not be considered using mechanical processes. Laser drilling of such holes for micro/blind, micro/buried, and micro/interfacial can really only be effected efficiently using laser or plasma methods, depending on materials used. 4) As the Navy, as it always does and well much of the time, spends very much time and money on such issues, I'm sure it must recognize the type boards, no matter their class, should be considered only with MCM's or device substrates (BGA?s as one example) that is a whole other world from "regular" Class whatever types. Also, with the increasing ability to use ASIC's with down to .18 micron line widths on fairly "standard" BGA ball spacing (to .5 mm), we really don't need such a plethora of such small diameter holes in such thin substrates no matter their construction ? as paint thin dielectrics, etc. 5) As I asked on the TechNet forum, who really uses low resin content materials, as 7628, anyway in anything over a really cheap four layer board? Using 2113, and other higher percent to glass ratio materials, removes most of the problem being discussed either at hole wall junctures or those inner- plane. 6) The thing with extremely thin, unsupported "paint" or resin systems is an ongoing issue as well it should be. One of the reasons we created rigid/flex circuitry was to take advantage of very thin polymide film and adhesives in conjunction with foils. I have built, as have others, purely rigid MLB's using these materials and the CAF problem was never a problem, for obvious reasons, though other problems presented themselves as they continue doing. 7) I am in no way against CAF reliability studies or it's impact, positive or negative, on HDI systems that have few, if any, reliability data. It possibly could aid in finding that data but I know not how. My concern is spending too much time on that and not enough on finding better interconnect technology where CAF would not be a factor. This point seems a target rich environment to me as well as doing reliability studies associated with the environment. 8) I understand how glass fracturing can and does occur especially in not well managed drilling process conditions as poor feeds and speeds effecting hole "punching" instead of cutting ? while admitting this process cannot be managed perfectly anyway. Also, too wear can be a part of the poor process management equation. Too many hits, etc. but still, these are nearly micro holes and should not, most of the time, be mechanically drilled. 9) Micro delamination is micro-voiding most often except when micro-voids propagate. IPC-6012, for "normal" board performance and qualification requirements clearly indicates the "old time" requirements for void sizes in the laminate evaluation area. It is concerned as will with performance during thermal stress for qualification purposes. It also points to pre-conditioning specimens before subjecting them to thermal stress and shock conditions. This is analog to baking, or otherwise pre-heating, boards before soldering operations while elevating and otherwise removing moisture in the MLB structure anywhere, supposedly. 10) And this is far as I can go now is, again, all the thermal cycles boards undergo during their fabrication and assembly cycles. FR-4, at about a .2% hygroscopic level, is pretty "dry" anyway so I really have a hard time with the CAF issue here. Plus, after so many fabrication, assembly, and performance cycles ? over many years, doesn?t the salt and bromide issue kind of dry up? Well, the bromide issue doesn?t as it is inherently part of the resin system and is required to put out the fires. Polyimide has no bromine or fire retardant problems. Again, I am not being argumentative. Simply, I don't get it. However, folks far more knowledgeable and astute than I have really dug into the dirt, not being derogatory here, to find this stuff. My hat?s off to them for doing it but what?s the alternative to more studies when the facts are in and we need new materials and processes to turn them into initially acceptable quality and long term reliability product. Again, why aren't we finding alternatives to the processes and parts instead of going down a path of finding CAF testing methodology. We have, you have, the proof CAF exists. So, lets find a process or material, or whatever that is CAF free, for lack of better terms. One thing of that I am sure is my book has lot's of room for upgrading over the years to come. I?m really not even trying to stir the pot here. I?m really just want to learn why realizing I have a lot of it to do, Earl --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------