Crimping & Soldering - Keys to Connection Performance and Longevity

[AJinFLA]

Hey at least you're employed.
Yeah, what a fiasco that was less than 2 weeks in. Figured you might have some insight on that. I guess things can go amiss at 7 TeV eh.
Sent a pm. I'll try to keep them straight over in Loudspeakers, though not too technical oriented their either.

later,

AJ

[jneutron]

Hey at least you're employed.
Yeah, what a fiasco that was less than 2 weeks in. Figured you might have some insight on that. I guess things can go amiss at 7 TeV eh.
AJ

Actually, they were not running beam at the time. They were training the magnets to achieve top current. One of the interconnect lap joints ran away thermally.

The solder joints are critical when you're running 10 kiloamps and the wire is approximately 1.5 cm wide and 1 or 2 mm thick.

Cheers, John

[tsteves]

jneutron
You're working at the LHC?!!!

One thing to note, much of the solder technique depends upon pre fluxing, or not pre fluxing. I agree with your technique as long as the work gets up to temperature. Inexperienced solderers may try it and not get things up to temperature, especially with speaker connectors.

[sparky77]

For starters, I think tls will even agree with me, start with a good 60/40 rosin core solder, heat both parts till the solder starts to wick into the parts being joined... thats about all there is too it.

One note is that with some insulated wires the insulation will tend to shrink back under the heat, so if the insulation on the wire is rather soft and rubbery, don't strip the insulation too far back. Grab the wire with a pliers and pull the insulation back till it tries to spring back, this way, when it warms up, it will spring back into position rather than melting back away from connection... making the connection much cleaner, even if wrapping with shrink wrap.

[Haoleb]

Another thing I would like to add is about taking care of the tip of the soldering iron. A good practice i have found is that before you go to solder a joint, clean off the tip usually with a wet sponge, (ideally wetted with Deionized water) and then tin the tip, and solder your joint. Its easier to have a wetted tip vs a dry one when you go to solder because if you have a small amount of molten solder on the tip when you touch it to the work it tends to transfer the heat better. Then before you return the iron to its stand re wett it again so that the tip has a blob of molten solder on it while its sitting in the stand which will keep it from oxidizing.

Also, when it comes to De-soldering, I have found its easier to desolder old joints by first adding in more fresh solder as it seems to make the old solder melt and flow more easily and it can then be more easily extracted with wick or a sucking device. I prefer wick for most jobs, And for the big jobs removing the majority with a sucker and then wicking up the rest.

also, The BEST wick i have ever used is techspray prowick I like the blue one because its just about the perfect size for everything. That stuff is a priceless tool when it comes to desoldering joints on circuit boards and so on.

[jneutron]

jneutron
You're working at the LHC?!!!

No. (but I did stay at a Holiday Inn Express last night)

My experience with the design and fabrication of superconducting lap joints pre-dates the LHC. I detailed the issues and concerns about 12 years ago, but the information obviously did not make it down to the assembly level where the rubber meets the road.


My experience includes about 4000 of these lap joints, using R type paste flux and tin/silver eutectic. They run at 6300 amps. There have been no catastrophic failures in 9 years of operation. A testament to the abilities of the gentlemen who actually did the work (what, you think they'd allow an engineer to work with dangerous stuff??)

Cheers, John

ps..I've worked on LHC stuff, but not the main ring components..I'm just small potatoes...

[Midcow2]

Midcow2
I can tell you are an old school solderer like me!
But I would like to comment on a few of your comments... not to nit pick, just to clarify.

This is sometimes a solution, but for one thing it depends on your pain threshold! If the clip is used directly on the bare wire and contact the clip is a heatsink, if used to hold the wire farther back it is way too time consuming to set up. Good solderers have callouses!


You need to try to bring both the wire and contact up to the proper temperature at the same time. If you are soldering a "big honking" spade lug (as Tom Andry might say) to a comparatively smaller wire, you need to spend more time heating the spade than the wire. So you'd wet the iron and pre-heat the spade until it gets close, and then heat both wire and spade and apply solder to the joint, not just the wire. Applying solder to just the wire gives you a blob, not the concave look you want. It takes practice to time things out.

Tsteves,

Thanks for your comments

Later

MidCow2

P.S. - I just gave you a scaler thanks --- notice you have 3 green chicklets now

[tsteves]

There are no small potatoes in projects like that! Everything is critical.
It's an honor having you in the discussion! Thanks for taking the time to share.

Tom

[tsteves]

Thanks Midcow2!
BTW
I'd wrestle an alligator or even a crocodile for your plasma!