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July 2010

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Subject:
From:
Eric Christison <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Eric Christison <[log in to unmask]>
Date:
Fri, 2 Jul 2010 16:12:27 +0100
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I'm wondering about an issue we have with the dimensional stability of a
substrate made of FR4.

We're finding it's deforming during a flex attach operation, not by much
but enough to cause us a problem. We use ACF and a hot bar. The
substrate sees a temperature of 155 deg C for about 10 seconds. Someone
suggested that the movement may be due to incomplete curing of the
substrate.

I'm wondering if a temperature of 150 deg C for 10 seconds is likley to
have any effect at all on the matrix.

If it did, would the volume of the matrix increase, decrease or stay
much the same?

I realise that we'll see deformation due the application of pressure as
well but in some instances the substrate seems to be moving in the wrong
direction.

Thanks,

--
Eric Christison
Consumer&  Micro group
Imaging Division

STMicroelectronics (R&D) Ltd
33 Pinkhill
Edinburgh EH12 7BF
United Kingdom

Tel:	+44 (0)131 336 6165
Fax:	+ 44 (0)131 336 6001




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