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November 2001

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Subject:
From:
"<Peter George Duncan>" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 15 Nov 2001 16:26:40 +0800
Content-Type:
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Hi, Pat,

HMP solder has a melting point about 100 degrees lower than your example
for electronics. Depends what you are soldering, but most components have
an upper temp limit for the dies around 230 deg C and a few go to 250 deg
C. Beyond that you risk internal damage.

In-service temperature excursions depend on the operating environment and
are limited by, and to, the rating of your components. Commercial parts are
rated between -20 deg C (at best) and +70 deg C. Industrial parts are rated
between -40 deg C and +85 deg C, while military parts are rated between -40
deg C and +125 deg C. Outside of these temperatures, the components may
work, but their specified performance is not guaranteed. They should not
see temperatures approaching soldering temperature in operation - they
definitely wouldn't survive for long at that.

Temperature settings for soldering should be 20 to 30 deg C above
liquidous, but watch out for the max case temperature of the components -
you may be getting pretty close to that with these settings. You will have
to tread a fine line between peak temperature and its duration to get the
boards to solder without damaging the component dies.

Good luck

Peter Duncan





                    "Diamond, Pat"
                    <PDiamond@WESTO        To:     [log in to unmask]
                    NAERO.COM>             cc:     (bcc: DUNCAN Peter/Asst Prin Engr/ST
                    Sent by:               Aero/ST Group)
                    TechNet                Subject:     [TN] Solder temperature question
                    <[log in to unmask]
                    G>


                    11/13/01 04:17
                    PM
                    Please respond
                    to "TechNet
                    E-Mail Forum."






/Dear all,

I'm looking for some advice on the threshold limits for solder
temperatures,
if for example, HMP solder is solidus/liquidus at say 296-301 deg C, what
is
the highest temperature excursion it can see in service before the
properties of the soldered connection are affected?

I heard somewhere that as a rule of thumb you should allow around 40 deg C
below the melting point of the solder being used.

Any help/advice that you can give would be appreciated.

regards,

Pat Diamond
Weston Aerospace
Farnborough
UK

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