Crimp Good/Crimp Bad

[echo]

NASA/military doesnt want flux on the solder connections. They have VERY high cleanliness standards for circuit boards. Why? Corrosion over decades of use. So they make us clean everything in a high pressure soponifier solution in a special machine. The high pressure solution can get into sealed parts and ruin them! And the thing is, its only old fashioned acid fluxes that corrode things. Rosin fluxes if reasonably cleaned wont hurt a thing. Ah but it gets deeper! Acid fluxes actually give a better solder joint than rosin fluxes! Acid flux is easily washed away with low pressure soap and water! So theres NO CHANCE of it getting into sealed parts! I know this because I work on a bench every day for 30 years soldering things. But...the ding dong people who sit behind a desk all their lives and write the specs dont have a clue. They make us use rosin flux (which wont hurt a thing) make us wash the boards in a high pressure cleaning machine (which can ruin the parts) which produces an inferior (but adequate) solder joint!

That's hilarious! Typical suits thinking they're doing things more efficiently!

Its even more unbelieveable than that. I think these specs are more about politics that actual production reality. (if something fails something (or someone) must be made to blame)

[DiscoPete]

An electronics instructor once told me that wire wrapping is superior to solder joints. I think he said it was more resistant to vibration.

Well....maybe. A properly done solder joint is strong, but so is a proper wire wrap.

Anybody know what's the real deal with that?

[echo]

Yep. Wire wrapping is very good. We used to do that alot, although I never did it myself. Right now we dont have any contracts that require it. Ill get ahold of one of the old timers who used to do it and find out all about it.

[Chiba]

It's best to use a ratchet style crimper, never the combination crimper/wire cutter, if you want a reliable joint.

Pshaw, Jerry. That ain't NASA spec.

--chiba

[BchrisL]

A solderless crimp is better than a soldered, uncrimped joint because the heat generated by high current through the connection can melt solder, resulting in a failed joint.

It's best to use a ratchet style crimper, never the combination crimper/wire cutter, if you want a reliable joint.

+1 ( the ratchet style is expensive though, but it will "git 'er done" right.

Jerry, Chris, as part of my cruise control research, I talked to a guy who mentioned "rolling" crimpers which he said were better than traditional crimpers. Do you know what he's talking about and is it true?

Thanks!

Rolling crimpers is a new one to me. I would like to see what they are.

[echo]

An electronics instructor once told me that wire wrapping is superior to solder joints. I think he said it was more resistant to vibration.

Well....maybe. A properly done solder joint is strong, but so is a proper wire wrap.

Anybody know what's the real deal with that?

Heres the real deal. We make the communications system for the Aegis cruisers, destroyers, and frigates known as IVCS. Basically its an old fashioned telephone exchange. The heart of it is the backplane. The backplane is made of of about a bazillion wires all hooked up to each other. Its about four feet by two feet by three or four inches deep. Its like a bunch of rats made a nest out of a thousand miles of very thin insulated wires. Its all tangley looking. The wires are all interconnected sometimes two together, three together, or even ten together. There are held together (at the bare ends) by a very thin wire that is wrapped tightly around them. Basically the backplane is built on a computer controlled machine that works very fast. There are tens of thousands of connections. Once it is built the backplane is hooked up to a computer that tests are the connections. Where there are bad ones a worker goes into the rats of wires and fixes them. They use a handheld gun looking thing which wraps the very thin wires around whatever connection that has to be made. We dont build the backplanes anymore but when we did people spent their entire careers (30-40 years) doing nothing but making these wire wrapped connections, maybe be hundreds or thousands of them aday.

[ylexot]

I got some of these:
http://www.harborfreight.com/cpi/ctaf/d ... mber=97420

...and haven't had to do any electrical work since Of course, I do have some planned. I'll get to it some day and be able to see how well they work.

[JimVonBaden]

I got some of these:
http://www.harborfreight.com/cpi/ctaf/d ... mber=97420

...and haven't had to do any electrical work since Of course, I do have some planned. I'll get to it some day and be able to see how well they work.

I have them, and they work great! I have used them a LOT!

Jim

[BchrisL]

I got some of these:
http://www.harborfreight.com/cpi/ctaf/d ... mber=97420

...and haven't had to do any electrical work since Of course, I do have some planned. I'll get to it some day and be able to see how well they work.

I have them, and they work great! I have used them a LOT!

Jim

That is a bargain! Do they have die sets to crimp insulated as well as open barrel (like the ones in original pictures on page one) uninsulated terminals?

[JimVonBaden]

I got some of these:
http://www.harborfreight.com/cpi/ctaf/d ... mber=97420

...and haven't had to do any electrical work since Of course, I do have some planned. I'll get to it some day and be able to see how well they work.

I have them, and they work great! I have used them a LOT!

Jim

That is a bargain! Do they have die sets to crimp insulated as well as open barrel (like the ones in original pictures on page one) uninsulated terminals?

Not exactly, but the jaws are adjustable, so they can be used similarly.

Jim

[RocketMan]

Personally, I like to 'tin' my wires before crimping them. This usually eliminatesstary strands.

We found that the lead/tin solder was higher in resistance and in a crimped connector would heat under load more than a conductor without tinning. The constant heat/cool cycle would lead to failure of the connector due to metal fatigue brought on by the repeated expansion contraction of the joint.

can't say I've ever worried about my joints expaning or contracting.....






but then I generally use a pipe...









no wait,








wrong forum







nevermind..........


RM

[Deano]

[DiscoPete]

An electronics instructor once told me that wire wrapping is superior to solder joints. I think he said it was more resistant to vibration.

Well....maybe. A properly done solder joint is strong, but so is a proper wire wrap.

Anybody know what's the real deal with that?

Heres the real deal. We make the communications system for the Aegis cruisers, destroyers, and frigates known as IVCS. Basically its an old fashioned telephone exchange. The heart of it is the backplane. The backplane is made of of about a bazillion wires all hooked up to each other. Its about four feet by two feet by three or four inches deep. Its like a bunch of rats made a nest out of a thousand miles of very thin insulated wires. Its all tangley looking. The wires are all interconnected sometimes two together, three together, or even ten together. There are held together (at the bare ends) by a very thin wire that is wrapped tightly around them. Basically the backplane is built on a computer controlled machine that works very fast. There are tens of thousands of connections. Once it is built the backplane is hooked up to a computer that tests are the connections. Where there are bad ones a worker goes into the rats of wires and fixes them. They use a handheld gun looking thing which wraps the very thin wires around whatever connection that has to be made. We dont build the backplanes anymore but when we did people spent their entire careers (30-40 years) doing nothing but making these wire wrapped connections, maybe be hundreds or thousands of them aday.

Thanks, Echo.

Yeah, I've seen those telephone backplanes that look like a rat's nest of wires. I'm not surprised that wire wrapping would be used there.

Wire wrapping can also be used to connect conventional components on a circuit board. The circuit board has tall, thin, square metal pegs arrayed on it and the component leads and connecting wires are wrapped on the pegs to connect up the circuit. It is tedious to build and a pain to repair when replacing components or looking for a bad connection. The only time I've ever seen a wire-wrapped circuit was on a project we had to build in tech school. Such circuits must have a damned near heroic resistance to vibration, or some other huge advantage over a printed circuit board, to be worth the trouble.

[wiredcur]

Interesting discussion but I really want to know why the subject wasn't "Good Crimp/Bad Crimp"?

[Deano]

Here's a story about one of the bad chimps:

http://ace.mu.nu/archives/077789.php





Oh, wait....never mind