“Never solder vs crimp” logic?

I was interested to see reference to wire-wrapping. When I was involved in prototype electronics in the 1980s, my colleague who built the stuff use wire-wrap almost exclusively to build the circuit boards (no one-off PCBs in those days; it was Veroboard and wire interconnections). He swore blind that the electrical connectivity was better than a soldered joint, and the connections were very quick and easy to do with the right tool. Our circuit boards were used in an aircraft (Twin Otter), and subject to a lot of vibration and shock loads. We never had a failure, and these were pure wire-wrap with no extra solder.

We used soldered joints elsewhere, especially to connectors, and I've soldered a very large number of D-type connectors, but the circuit boards were built using wire-wrapping. It has obvious advantages when you're changing things in a prototype, but they do work very well.

That said, it's difficult to see how wire-wrap techniques would be useful on a boat, unless you were wiring a panel. It also doesn't work with stranded wire.
 
It is not wire wrapping (no square post, and solder is still used etc), but a useful trick with a difficult solder joint is tightly wrapping the components together with fine tinned wire. The aim is to to hold everything together before the solder is applied. This can be helpful especially in tight awkward situations. When the solder is applied it fuses everything together forming a neat and strong joint.
 
ip485 said:
lw395 - thats is a very good point - but wouldnt the tin still oxidise when crimped and infact would you not have two different metal then in contact? Isnt it likely the surface area effectively bonded together with a crimp would be much less than the total contact surface area with mulit strand being wound together over some mm's. J...l.
Click to expand...
No, a proper crimp moves copper around to the extent that's it's almost a cold weld. Oxides are sheared off and surfaces bond together. Market stall crimp tools are not like that off course.
 
AntarcticPilot said:
I was interested to see reference to wire-wrapping. When I was involved in prototype electronics in the 1980s, my colleague who built the stuff use wire-wrap almost exclusively to build the circuit boards (no one-off PCBs in those days; it was Veroboard and wire interconnections). He swore blind that the electrical connectivity was better than a soldered joint, and the connections were very quick and easy to do with the right tool. Our circuit boards were used in an aircraft (Twin Otter), and subject to a lot of vibration and shock loads. We never had a failure, and these were pure wire-wrap with no extra solder.

We used soldered joints elsewhere, especially to connectors, and I've soldered a very large number of D-type connectors, but the circuit boards were built using wire-wrapping. It has obvious advantages when you're changing things in a prototype, but they do work very well.

That said, it's difficult to see how wire-wrap techniques would be useful on a boat, unless you were wiring a panel. It also doesn't work with stranded wire.
Click to expand...

Wire wrapping, done properly knifes the corners of the square pin into the copper wire and leaves the wire tight on the pin.

I've got some 70s wire-wrapped equipment and it's starting to play up now.
ISTR wire wrap was OK for small signals but didn't take much current, even for the small wires used?
 
Wire wrap was using solid wiring to mainly interconnect edge connect PCB frame racks. I used then when building S100 based computer systems to connect processor cards with separate RAM, ROM and I/O cards.

The wire wrap connectors had square corners that would cause the solid copper wire to cold weld at the sharp corner.

There were/are both hand and powered wire wrapping tools. The process did not last long as PCB back plains started to take over, then single board PCB's

wirewrap_fig6.jpg



https://en.wikipedia.org/wiki/Wire_wrap
 
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lw395 said:
Wire wrapping, done properly knifes the corners of the square pin into the copper wire and leaves the wire tight on the pin.

I've got some 70s wire-wrapped equipment and it's starting to play up now.
ISTR wire wrap was OK for small signals but didn't take much current, even for the small wires used?
Click to expand...

Rogershaw said:
Wire wrap was using solid wiring to mainly interconnect edge connect PCB frame racks. I used then when building S100 based computer systems to connect processor cards with separate RAM, ROM and I/O cards.

The wire wrap connectors had square corners that would cause the solid copper wire to cold weld at the sharp corner.

There were/are both hand and powered wire wrapping tools. The process did not last long as PCB back plains started to take over, then single board PCB's

wirewrap_fig6.jpg



https://en.wikipedia.org/wiki/Wire_wrap
Click to expand...

Thanks! In all cases, we were looking at TTL level signals, so no power concerns. And yes, some of the stuff was S100 - the CPU I used was an S100 single card computer board with (gasp!) a Z80 processor and (wait for it...) about 2k of RAM! My job was programming the Z80, using a development system comprising an Osborne 1, Wordstar, ASM and LINK! The wire-wrap was mainly interface cards for the motley collection of equipment (not many proprietary boards for custom built 300MHz ice-sounding radars!)
 
Back to the original question:
A pragmatic answer is that I use a good quality crimper because I can't be troubled to heat up a gas powered soldering iron for one or two wires and I don't have 240V power onboard, so crimping it is.
 
RivalRedwing said:
Back to the original question:
A pragmatic answer is that I use a good quality crimper because I can't be troubled to heat up a gas powered soldering iron for one or two wires and I don't have 240V power onboard, so crimping it is.
Click to expand...

Good point. I get it might be faster for individual joins.
 
thinwater said:
Wago connectors do not meet marine standards for pull-out resistance. I tested this and other methods for an article.

Chock blocks do.
Click to expand...

Ah. Adding chock blocks to the mix will make this thread explode.

I would assume that stress relief is out of scope and dealt with. For example the NASA specs are quite explicit about dealing with this.

Is there a link to your article or is it a paywall?
 
thinwater said:
Wago connectors do not meet marine standards for pull-out resistance. I tested this and other methods for an article.

Chock blocks do.
Click to expand...

Quite. But I don't aim to leave any wiring in tension near connections. If wiring is supported adequately or left with enough slack, tension should not be a huge issue?
 
pagoda said:
Quite. But I don't aim to leave any wiring in tension near connections. If wiring is supported adequately or left with enough slack, tension should not be a huge issue?
Click to expand...

But the pull resistance is an indicator of whether the wire is held securely in good contact with the terminal.
If it pulls out easily, it might be in marginal contact and prone to failure from corrosion.
A crimp that fails pull test is a bad crimp, which won't be reliable.
Not so sure with Wago-type connectors, because they are a spring action, so the contact force will still be there if something moves a bit.

You would expect it to be easier to pull a mains plug out of a socket than to pull the wires out the back. Both are good for the same current.
 
gregcope said:
Ah. Adding chock blocks to the mix will make this thread explode.

I would assume that stress relief is out of scope and dealt with. For example the NASA specs are quite explicit about dealing with this.

Is there a link to your article or is it a paywall?
Click to expand...

It was in Practical Sailor Magazine.

Pull out strength is just a surrogate for robustness. Particularly small wires, are not very secure. Stress relief is a great idea. During service, sometimes wires get horsed on by accident. You know they do.
 
So, some other info about this thread (this is a draft from a few days ago... work go in the way).

My boat, built by a reputable UK Boat builder (since gone bust) seems to have issues with Crimps.

I seem to be replacing lots of the female space connectors as they break on the rounded parts the grip the male connector. So you think you have a join, that sometimes passes a connectivity test, sometimes not. Usually when you do not want it to. These problems initially wound me up no end trying to debug issues like the fridge not working.

Secondly, the other issue I have found, which is odd for what looks like a pro job, is some of the crimps are lose and fail a pull test. The old crimps do not have heat-shrink, just clear covers. So again a non-obvious fault that is sometimes hard to find.

Third thing is that until recently found it hard to make a good crimp. I blame the crimpers. Well really it is the person who brought it (me) who got the wrong jaws, not knowing there are lots of different sorts. I often have many goes to make a crimp that would survive any pull test.

Finally none of my solder joints appear to have ever failed. Yes I do cover with glue lined heat shrink and make a good mechanical join with sufficient overlap, as well as supporting the wire.

And yes ... I also have the "wire changes colour in the middle, unseen somewhere" which also leads to me worry about the join (ref crimps failing above).

I might need crimp training!

Thanks for all the replies so far. Great discussion and some really good observations. Thank you.
 
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