Hello Brad,

Thanks for responding!

Our board design is two layer (1/2 oz. copper sandwiching .030" FR4). I only
took one semester of deformable solids, but I agree that a standard layer of
LPI should not be able to bow a .030" stack to any significant extent... The
concern was raised by our vendor (three letters - starts with a D)

Your input has emboldened me; we're going to stick with a full mask on the
BGA side. I'll keep you posted :o)

Thanks again!

Tom Ochenas
Maxtek Components Corporation


-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Thursday, May 30, 2002 5:58 PM
To: [log in to unmask]
Subject: Re: [TN] soldermask ring v. full coat for BGA design


Hello Tom,

My that is an unusual request/requirement.  .004 is the min I like, it can
go down to .003.  Below that... I wouldn't trust it.  Actually the "ring"
configuration you speak of is unique enough that I believe it will be
problematic.  I would not do it.

As to the statement of board warping due to soldermask on one side; I
disagree.  Soldermask, especially LPI is pretty friendy stuff relative to
warp.  Unless there is some unusual condition of board thickness or finish,
one side solder mask will not warp a board.

Brad Saunders
Coretec Boston Office
781 858 0783