Hello all you Techies ou there. First off - Happy New Year to one and all - trusting this year will be a tad better than the last one we had.

I've been reading the postings about hole-wall sep. I must agree with Susan on the point she brought up - on " Low Tg material". When using low Tg material - by the time an aggressive desmear or etchback is applied....at times...all is left but the glass bundles. Then of course a good glass etch...and voila...not much there.

Poor conditioning in the PTH process....and of course....it is much more difficult to deposit copper on glass strands .... and eventually by the time we get to "Thermal Shocking" the board " HASL " ..... lucky if anything is stuck to anything.

Also, a fast accelerated electroless deposit doesn't help the condition either. Gouging during drilling adds to the final condition....and so on and so on.

Susan....not for the sake of sounding rude...but isn't microsectioning a visual assessment?

Hole walls do explode..especially when there isn't enough electroplated copper in the through-holes. Any good microsection will diplay that. Copper must attain a certain thickness in order to take the HASL application. If not, you'll usually see the solder being sucked in on one side. If you section that hole, 9 out of 10 times one will see, that there is an insufficient electroplated copper deposit in it.

But in my most humble opinion, there are several causes as to why hole-wall pull away,resin recession and separation can be all linked into one major situation...every board shop has a situation...not a problem...and eventually...every situation is finally put under control.

If one saw sections with copper adhering to the inner layers and not the resin, i would have to believe that there was no copper in the hole wall to begin with. But again, that's only my opinion...and we know what they say about opions...they're like the nose on a face...everybody has one.

Cheers

Rick Fudalewski

Florida Cirtech