Hi Pat! Wow, what a soldering process - sounds like something "Tim the Tool
Man" would thoroughly enjoy! Actually the process you described is called
flame or torch soldering and is fairly common in a number of industries.
Also, many people consider any process which applies a filler material
using a temperature above 800F to be considered brazing. The torch
temperature impact on the solder is not the problem but you do need to have
a good flux plan. The flux chemistry choice will determine what kind of
surface preparation you need and how much solder alloy oxidation will be an
issue. The mechanical joint fit design and the diffusion of other surface
finishes into the soldering joint need to be understood also. You could
also consult with companies who supply brazing materials/services as they
may be able to assist with some of the design issues. Good Luck.
Dave Hillman
Rockwell Collins
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"Diamond, Pat" <[log in to unmask]>@ipc.org> on 07/25/2002 03:05:32 AM
Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
to "Diamond, Pat" <[log in to unmask]>
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To: [log in to unmask]
cc:
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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