Dear all,

Wanted some inputs on a problem which we are facing currently

We observe a separation, rather tendency for separation, on 2.5mm thick
MLB boards when subjected to 3X 288 deg 10 sec thermal stress. This is
mostly found only on one side ie in one of the outerlayers, and very few
on both outer layers. The inner layers are intact.

We use N4000-6 as well as 4000-13EP laminates for fabricating PCBs and we
use laminate construction for the stack up. We do Plasma desmear followed
by a run thru permanganate too. We tried various parameters in drilling as
well as reviewed all the basic electroless / electroplating parameters ,
and all were found as desired.

We use 1-1.2 microns thick electroless copper followed by a flash
electrolplated copper of about 12 microns before pattern printing. The
board is then pattern plated to achieve a minimum PTH copper of 30
microns.

Looking forward fro ur inputs

Rgds

Pradeep






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