WW91IGhhdmUgbWljcm8tc2VjdGlvbmVkLCBzbyB5b3UgY291bGQgY2hlY2sgdGhlIHJvdWdobmVz cyBhbmQgcGxhdGluZy The above means I might agree if I understood what you were trying to say. Looks good though. I just wrote some stuff about BGA's in an earlier posting. Dull stuff really and very old as everyone knows. Some of it may be pertinent here. I talked about developing a simple process to form micro vias in Kapton. I used plasma to "drill" 3 to 5 mil holes in 1 mil thick material and bonded the sheet over the MLB top and bottom. Essentially it was a rigid/flex board without the flex part. Anyway, the concept worked very well but for some outgassing issues as I stated before. The cause turned out to be some problems associated with using a standard acrylic adhesive to bond the Kapton to the outer layers and effect the plating process. Not that it matters here, but used the same technique on inner layers as buried vias. Someone patented the idea, or one similar, for micro vias, not that that matters here either. Just writing myself a note. Is that legal on this forum? uvia outgassing can be a problem but shouldn't be so. I can only guess it is an issue relative to what you are experiencing. Outgassing out of any via is cause for concern and most causes have been discussed many times. You know the ones as moisture, process chemical entrapment, and all the rest. Of course, it could just be entrapped air in the via. MoonMan --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------