From: Scott Westheimer
Date: 3/17/97

The addition of copper thieving on the actual inner layers an add to the
panel is normally a good idea for evening out pressure. However there is a
lot more reasons way you would have warpage. Non-symmetric designs and
lay-up, unbalanced coppers and glass weights, excesses lamination heat up
and cool down cycles, and distortion during thermal excursions i.e S/M
bakes, and HASL. You should discuss these with you fabricator.

The use of cross hatch can be a problem when it comes dry film imaging.
Sometimes the hatches come up and can cause opens during processing. I
would also recommend that before you use them that you discuss with the PCB
fabricator. 

----------
> From: chuan <[log in to unmask]>
> To: [log in to unmask]
> Subject: Re: DES: Cu fills on circuit layers
> Date: Saturday, March 15, 1997 6:42 PM
> 
> 
> Thomas,
> We use round feature on the side of panel "TRYING" to reduce the warpage.
> However, up to now we have not experience any significant effect of
> improving warpage by these dot. In fact these dot even contaminate our
> etching chamber! I suggest better control of your baking, and HASL
process
> (especially how you design your rack), that should be a better cure.
> 
> Good luck
> 
> At 18:57 97/02/05 +0800, you wrote:
> >
> >Hello Siggers,
> >
> >Here's the scenario:
> >
> >Board warpage has become an issue in our shop so we are adding fill to
> >open areas on the boards. Our fab houses like a round or square feature
> >of varying density. Mentor (version A3F) only has solid or hatch as
> >options. We have been using the hatch but it may not be optimum. CAM is
> >probally not an option because we must have 100% repeatability between
> >revisions, (Compliance approvals etc..) this is also why we can't let
> >the Fab house do it for us. Oh yeah - We'd like to keep this automated.
> >
> >Here's the Q's:
> >
> >Fab Folks - What would you consider to be an adequate hatch pattern?
> >.025 width on .05 grid? (If hatch is our only option) What would you
> >recommend for a spot pattern?
> >
> >Designers - Are there any other Mentor users adding fill areas and how
> >do you handle it?
> >
> >Thanks in advance for any comments or suggestions.
> >
> >Ty Thomas
> >Sr Product Packaging Designer
> >Paradyne Corp.
> >Largo FL
> >[log in to unmask]
> >813-530-8434
> >
>
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> >
> >
> Chris Wu
> Engineering Dept.
> Wus Printed Circuit (Kun Shan) Co. Ltd.
> Tel: -86-520-7314977/78/79 ext. 6800
> Fax: -86-520-732119
> email: [log in to unmask]
> 
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