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July 2003

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Subject:
From:
"Barr, Bob" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 16 Jul 2003 11:30:20 -0400
Content-Type:
text/plain
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text/plain (60 lines)
Doug,

I had an experience once with failing crystals in this package, but not due
to soldering. Failure analysis by the component vendor showed internal
physical damage to the crystal. Our only conclusion was that a reel may have
been dropped by the operator damaging some of the components. The problem
has not occurred again since then. Components of this type are somewhat
sensitive to physical damage. This is just another failure mode you may want
to consider.

=========================
Bob Barr
Manufacturing Engineering
Formation, Inc.
=========================

> -----Original Message-----
> From: McCall,Doug [mailto:[log in to unmask]]
> Sent: Wednesday, July 16, 2003 11:10 AM
> To: [log in to unmask]
> Subject: [TN] HC49 SMT Crystals and Reflow Soldering
>
>
> Hi All
>
> Does anyone have any experience of HC49 crystals failing test
> following
> Reflow Soldering with a standard 183 Deg-C Eutectic solder
> paste (Sn62 Pb36
> Ag2).
>
> - The max temp found at crystal is 225 Deg-C;
> - Over 200 Deg-C is approx. 53 Seconds;
> - The crystal is over 200 Deg-C for 22 Secs longer than the component
> datasheet;
> - Pre-heat is ramping up at 1.8 Deg-C per second;
> - Time to 140 Deg-C is to long by 47 Seconds;
>
> The profile may have to be changed slightly, but any experience of
> failing SMT crystals and failure modes would be appreciated as the
> crystal spec apears to be very close to our profile parameters.
>
> Thanks.
>
> Regards,
>
> Douglas I McCall,
> PCB Manufacturing Engineer - Eastbourne,

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