As others have said there is insufficient data here Pradeep, you need to
describe the issue fully. I.e. are the boards delaminating in specific areas
such as a BGA via hole field? Size/description of the d-laminations, is it
the top or back of the board etc - photo's would also help.

Regards 

John Burke
(408) 515 4992


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Pradeep Menon
Sent: Thursday, April 01, 2010 11:11 PM
To: [log in to unmask]
Subject: [TN] Outer layer separation
Importance: High

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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