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December 2014

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Subject:
From:
Anil Kher <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Anil Kher <[log in to unmask]>
Date:
Wed, 31 Dec 2014 10:20:45 +0530
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Agree. Want to know how much distortion could one expect. 20, 30, 50 um?
Anil
On 31 Dec 2014 01:13, <[log in to unmask]> wrote:

> Anil,
>
> FR-4 is composed of several layers of epoxy coated fiberglass fabric.
>
> The fabric has a warp and weft not unlike cloth.
>
> When the material is coated with the "B" stage epoxy it is subjected to
> strains from the conveyor.
> When the layers are added between copper there may be as many as three
> different fiberglass fabrics, all will have different strains.
> Heat up and cooling rates from the pressing or lamination cause additional
> strains to be applied.
>
> Movement during your processing are a product of the fabric, for instance
> the thicker glass (ie 7628) moves less, the thinner and higher resin
> content fabrics move more.
>
> There is no one standard for movement.  Work with your suppler technical
> support to find the best dimensional product but this may be a tradeoff for
> other factors.
>
> hope this helps,
>
> Chuck
>  ------------------------------
>
>  *Charles W. Brummer* | 3M Manufacturing Engineer
> 3M Electronic Solutions Division
> 3M Canoga Park, 8357 Canoga Ave. | Canoga Park, CA 91304
> Office: 818 734 4930
> *[log in to unmask]* <[log in to unmask]> | *www.3M.com*
> <http://www.3m.com/>
>
>
> This message (including any attachments) may contain material, non-public
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>
>
> From:        "Anil Kher" <[log in to unmask]>
> To:        <[log in to unmask]>
> Date:        12/30/2014 12:33 AM
> Subject:        [TN] Fr4 panel distortion
> Sent by:        TechNet <[log in to unmask]>
> ------------------------------
>
>
>
> We have yield issues in production of 500 mm size panels in pattern to hole
> alignment within 50 microns.
> Never thought fr4 panel will distort.
> Can anyone guide me on distortion of panel - 0.2 and 0.4 mm thick h/h
> Thanks a lot
> Anil Kher
>
>
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