I have a board that has about one quarter of the component side
covered with a copper pour.  The rest of the board just carries signal
traces.  This board has been hand assembled and soldered for over a year

without a twist.  Now we are sending it through a wave solder and
noticed a twist.   It is within spec (1.5%) but it is disturbing.  We
have received two pieces of advice on how to counteract this twist.  1.
To make the copper pour a cross hatch  2.  To make a similar copper pour

on the solder side to mirror the component side.
    I was given advice that you should strive to have less than a 20%
difference in copper in any area between any two mirrored layers.  Both
these suggestions seem to provide this solution.  However, I was told
that I might get a bend in the board if I try #2.  I was also concerned
about reducing the shielding that the copper pour provides if I try #1.
Any ideas??  Can this be minimized greatly by Fab and assembly
considerations alone?  Thanks.



--
Matthew M. Leary   (617) 338-4171 Tel
Newgrange Design   (617) 338-6748 Fax
8 Winter Street   Suite 508  email: [log in to unmask]
Boston, MA 02108   Web: http://idt.net/~ntbost19/

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