Doug,
We use an SMT crystal, which survives our reflow, but has problems with
hand soldering. The solder holding the crystal in the package reflows when
the iron is held on the package instead of the PWB pad for an extended
length of time. The crystal can also be damaged electrically by too much
input power. You will need to do a failure analysis to determine how the
crystals are failing.
Jim Carlson
Rockwell collins reliability Engineer
"McCall,Doug"
<Doug.McCall@BOCE To: [log in to unmask]
DWARDS.COM> cc:
Sent by: TechNet Subject: [TN] HC49 SMT Crystals and Reflow Soldering
<TechNet@listserv
.ipc.org>
07/16/2003 10:10
AM
Please respond to
"TechNet E-Mail
Forum."; Please
respond to
"McCall,Doug"
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,
BOC EDWARDS,
Marshall Road,
Eastbourne,
East Sussex,
BN22 9BA UK
Tel: +44 (0) 1323 501 147
Fax: +44 (0) 1323 509 824
mailto:[log in to unmask]
Regards,
Douglas I McCall,
PCB Manufacturing Engineer - Eastbourne,
BOC EDWARDS,
Marshall Road,
Eastbourne,
East Sussex,
BN22 9BA UK
Tel: +44 (0) 1323 501 147
Fax: +44 (0) 1323 509 824
mailto:[log in to unmask]
BOC Edwards is a part of BOC Limited
Registered Office: Chertsey Road, Windlesham, Surrey GU20 6HJ
Number 337663-English Register
Ultimate holding company: The BOC Group plc
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