1000 degrees is about the temperature of the hottest part of an
oxy-acetalene welding torch, the likes of which I have often used to repair
cars and other bits of machinery by melting bits of steel together. Please
note - "melting" and "steel".
Are the parts being heated, or the solder joints, actually seeing this
temperature, or are they such a large heat sink that much of the heat is
dissipated? i.e. where are you measuring the temperature?
At 1000 degrees, I would have thought the brass would have melted and the
st st parts be somewhat warped. The silver soldering would have come apart
as well, and as others have said the solder would be a nasty drossy lump of
oxide. Methinks there has to be more to this story than meets the eye -
what is this engineer's background? What has he designed before - and did
it work?
Sounds to me like it's not a very controlled, or controllable process, this
welding torch to do a bit of soldering. I confess I once (before many
people were born) tried to solder repair panels onto a car using a welding
torch. My theory at the time was that if I could apply enough heat
generally at soldering temperature, the buckling of the car's bodywork
would be minimised. I did manage to get the panels to solder after a lot of
trial and error, but the overall effect was not as predicted - the panels
still warped, the solder did tend to be very drossy unless I used a
carburising flame (oxygen-poor) and kept the flame from getting too close
to the panels themselves. Net conclusion - an unsatisfactory waste of a lot
of time - and flux and solder, and body filler to cover the warps in the
panels.
Peter
"Diamond, Pat" <[log in to unmask]> 25/07/2002 04:05 PM
Sent by: TechNet <[log in to unmask]>
Please respond to "TechNet E-Mail Forum."; Please respond to "Diamond, Pat"
To: [log in to unmask]
cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
Subject: Re: [TN] Overheated solder alloy
Dave,Roger,
this is not being used on a PCB or wiring harness, I will try to explain
but
it's a bit tricky.
One of our "Engineers" has come up with an RTD (Resistance Temperature
Device) assembly design which comprises of silver brazed peice parts
(st/steel),which are then joined to a tube (brass) internally, using solder
rings made out of solid 60/40 (both 20 & 18SWG) and using a flame torch to
heat the parts up (this was measured at 1000+ deg.C).
Added to this he has designed in HMP (221 deg. C) solder as a "sealant"
around the top of the assembly to seal the rod and the tube, also soldered
using a flame.
Oh I forgot, he has specified Multicore "Arax" as the fluxing agent.
Will these joints be reliable after seeing that temperature?
I would have thought the silver braze would also re-flow at the
temperatures
used, would they be affected?.
Is this guy crazy or is he a genius?
Does any of this make any sense!
regards,
Pat
-----Original Message-----
From: Dave Hillman [mailto:[log in to unmask]]
Sent: Wednesday, July 24, 2002 5:34 PM
To: [log in to unmask]
Subject: Re: [TN] Overheated solder alloy
Hi Pat! You will have molten Sn60 solder at a temperature of 1000C! Tin
boils at 2603C and Lead boils at 1750C so you won't start vaporizing the
Sn60 solder alloy until you get near the 1750 C point. I just have to ask -
why the concern of 1000C? Your printed wiring assembly will be quite toasty
and you would have molten solder running on the floor before you reach the
1000C mark!
Dave Hillman
Rockwell Collins
[log in to unmask]
"Diamond, Pat" <[log in to unmask]>@ipc.org> on 07/24/2002 08:38:17 AM
Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
to "Diamond, Pat" <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
To: [log in to unmask]
cc:
Subject: [TN] Overheated solder alloy
Technetters,
this may seem like a crazy question but.....what would happen to 60/40
solder alloy at temperatures of 1000 degrees C?
regards,
Pat Diamond
Weston Aerospace
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