Hey all ya'll!! (That better Doug? Hehehe...Doug told me last week that I wasn't using "ya'll" properly...hehehe) Just discovered 2 built-up assemblies at final QC that had some delamination blisters, and we're trying to figure out what happened... To give a little history about this board; we've been building them since November of last year. It's a 14" X 13" PTH board, 4-layer, .062" thick FR4, got close to 600 components on it. We build anywhere from 50-70 assemblies per day of this board. The bare boards have been coming from the same fab vendor and we've not had this problem at all in the past...and again, it's just on these two assemblies. We've not been baking the boards because we've not had a problem with them (we usually don't with FR4, we bake all our polyimide fabs though). I have some pictures of the blisters at: http://stevezeva.homestead.com/index.html The questions I have are: Can this sort of thing happen for some other reason that absorbed moisture? I don't think it was moisture related, the reason I feel that is there were no blow-holes, or pin-holes in any of the solder joints at all. It's been my experience that if a board has absorbed moisture, you'll see that soldering problem as well. I don't feel we over-temped the board either. I'm using the same wave profile that was created back in November of last year, and we've waved thousands of boards since then without a problem... Can a cross section determine what caused the blisters? Thanks! -Steve Gregory-