Hello Larry,
Just a few observations from my own experiences;

There appears to be no problem with Solder Mask Over Bare Copper with modern
masks.
(over tin/lead you would get bubbling of the mask when reflowed or waved.)
I have seen in the past where a black oxide finish has been used to promote
good adhesion.
The extra copper will heatsink the solder joints, but should be no problem
if you use thermal reliefs.
The use of cross hatches can make the board easier to fabricate. It is very
difficult to plate a board where there is a large solid copper area near
fine tracks.
As far as warping goes, I try to maintain an even and balanced amount of
copper on each side of the board. Sometimes hatching will help here.
RF board designs however will usually require solid copper fills for
electrical reasons.

regards,

Phil Dutton C.I.D.
Senior CAD Technician
IPC Certified Interconnect Designer

Tenix Defence Systems Pty Ltd
Systems Division - Adelaide
Second Avenue, Technology Park,
Mawson Lakes.  SOUTH AUSTRALIA  5095

================================
Phone   (08) 8300 4400 (reception)
Fax             (08) 8349 7420
email           [log in to unmask]
Internet Page   http//www.tenix.com
================================


-----Original Message-----
From: Larry Jindra [mailto:[log in to unmask]]
Sent: Tuesday, 24 October 2000 11:16
To: [log in to unmask]
Subject: [TN] Crosshatch vs Solid Fill


We are having some discussion of the pros/cons of crosshatch vs. solid fill
for copper ground planes on surface layers of multilayer boards.  Perhaps
someone can help me with some answers.

Is there a discernable difference in soldermask adhesion?
Does the extra copper detract from reflow or rework operations?
Is there a difference in board warp susceptibility?
Why would an electrical guy want one vs. the other?


> Larry Jindra
> TRW/Avionics Systems Division
> mailto:[log in to unmask]   ph (858) 592-3424   fax (858) 592-3606
>

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