Werner,
I always believed RoHS was a political decision the European solder people stood against. They had to work a viable solution, just like anybody else. Does anybody know which company had the hadron contract?
Regards,
Ioan Tempea, ing.
Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
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-----Message d'origine-----
De : Werner Engelmaier [mailto:[log in to unmask]]
Envoyé : Sunday, November 22, 2009 9:56 PM
À : [log in to unmask]
Objet : Re: [TN] NTC Large Hadron Collider Restarts
Hi Steve,
Sorry, I have not seen the arrangement and I do not if there is sufficient strain relief.
Werner
-----Original Message-----
From: Steven Creswick <[log in to unmask]>
To: [log in to unmask]
Sent: Sun, Nov 22, 2009 7:45 pm
Subject: Re: [TN] NTC Large Hadron Collider Restarts
Steve,
I admit that I should have taken more than a quick glance at the process
document which you presented, however, if the both parts of the joint have
been pre-tinned, AND the JOINT to be soldered is indeed brought up to 230C+,
why shouldn't the joint be reasonable?
My recollection is that the Sn96.5/Ag3.5 is a eutectic solder, melting at
221C, so the 230C is certainly a whole lot closer than I would prefer to run
with, but it should indeed have melted and bonded with the pre-tinned
surfaces.
Subsequent posts have discussed tin pest, etc.
My greatest apprehension is in regard to the stresses imposed in the joint
[any joint material] when transitioning from room temp to cryogenic and back
again. I hope there is some serious stress/strain relief built into the
joint structure!
Werner, since you have had the opportunity to see the instrument to some
degree, can you provide insight as to the physical size and potential delta
length which may be involved in the soldered joint?
What are the physical sizes of the 'leads'. Are they too large to join them
with a high-power ultrasonic welder, and do away with solder altogether??
Steve C
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of stephengregory5849
Sent: Sunday, November 22, 2009 1:50 PM
To: [log in to unmask]
Subject: [TN] NTC Large Hadron Collider Restarts
Some of you may have heard that the LHC (Large Hadron Collider) has
restarted after shutting down last year because of a reported bad solder
joint.
I have wondered what kind of solder was used for the connections of the
superconducting cables that failed in the LHC, I think I know now...SN96. I
also think I found out how they soldered them. Resistance soldering. Here's
the procedure:
http://tinyurl.com/yksdbt6
and another reference:
http://accelconf.web.cern.ch/AccelConf/e06/PAPERS/THPCH183.PDF
What bothers me in both of them, is that they are only heating the
connections up to 230 C. and caution not to exceed 240 C. Is that high
enough using SN96 to form a good metallurgical bond?
Steve
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