Wire for harsh environment

Question

One of the jobs I often have to perform is repairing the infra-red sensing headsets for BattleSports equipment.

Basically the headset consists of a pair of IR detectors and red LEDs for indication. They are worn on the head, and connect to the BattleSports gun via a coiled (Telephone Handset-style) cable.

One end of this cable has a proper RJ-11 (4P4C) connector, the other end is soldered directly into one of the sensor modules on the headset.

The cable used is really not the best cable in the world.

It breaks where it enters the gun, even with a rubber grommet
It breaks where it enters the sensor
It's not designed to be soldered

And on top of all that while doing the repairs I am finding the actual copper of the wire is getting badly corroded and oxidised by being outside all day every day (kids are not gentle with the kit). The wire gets brittle with the oxidization, and breaks are more common as it ages.

So I ask: is there a better kind of cable that is specially designed to resist oxidisation? I'm not asking for a specific product or anything, just if such a wire exists and what it would be called. From there I can try and source coiled cable, or as a last resort investigate custom cable producers. I just need to know what metal / alloy etc to look for...

Update:

Thanks to @RussellMcMahon I now have a term to search for, and a concept to look into. It just so happens that I bought a headset cable to try out to see if it was any good - closer examination shows that it is indeed made from this "Tinsel Cable" that Russell mentions.

enter image description here

And yes, I can attest that it is almost impossible to solder it.

For more detail here's some pictures of the headset end.

This is one of the two sensors:

enter image description here

The wire enters between the casing and the circuit board:

enter image description here

(That's fluff,by the way, not blood :P ). The wire is soldered direct to the circuit board (surface mount pads):

enter image description here

That's my attempt at soldering the tinsel wire there...

The most common break at the headset end is at the point the wire enters into the plastic casing. There's quite a bit of crimping pressure placed on the wire at that point, and bends there are usually fatal.

Hmm, is it possible to add an RJ-11 jack to the headset, and just use actual phone cable? Easy and inexpensive to replace those. — rdtsc, Mar 16 '15 at 05:55
Alas not. The headset consists of two small semi-spherical sensors on an elastic headband. They can't be modified. — Majenko, Mar 16 '15 at 09:40

score 4 · Answer 1 · edited Jun 11 '20 at 15:10

4

You may want to try horrible to work with fiendish to solder or otherwise terminate super nasty BUT stunningly robust & flexible "tinsel" - as used in old telephone and instrument cords when people wanted them to last.

A surprisingly large number of people still supply it.

Good commentary - 2011 Designing Cables for Increased Flexibility They say:

Tinsel Wire

For low voltage applications, tinsel wire offers the greatest degree of flexibility.

Tinsel wire is made by flattening the conductor material into a ribbon and then spirally wrapping one or more conductors around a strong fabric core. Tinsel conductors are typically made of copper and are often plated with tin or silver. Because the fabric core is what gives tinsel wire its strength, the conductors can be made very thin and flexible.

Micro photo of a single strand of tinsel wire – flattened conductors wrapped spirally around a strong fabric core

Tinsel wire made up of seven strands of tinsel conductor Due to the nature of the construction; tinsel wire is more expensive than common stranded copper wire. However in applications where both high flex life and tensile strength is required, tinsel wire, or cable made up of tinsel conductors, may be the best design choice.

enter image description here

By the containerload, probably

And many more aaand some of these are even relevant - ignore the Christmas decorations.

Wikipedia not marvellous

edited Jun 11 '20 at 15:10

Community

1

answered Apr 13 '15 at 14:20

Russell McMahon

147,325
18
210
386

I have a 6.2m handset cord that I have bought to experiment with. It looks like it may be made from tinsel wire, since it is almost impossible to solder and the wires are very fibrous. Maybe I should examine it under the microscope to check it out. – Majenko Apr 13 '15 at 14:33
1

Nasty tricksy horrible olde british telecom rubbish stuff. We hatesim, my precious. But they work so well. Not fair. Should not be so good. We HATESem. (Some of my very earliest electrical merging into electronics experiences involved trying to solder British Standard Tinsel [tm], finding it was only just not quite impossible, and wondering how real people did it. Methinks crimping suitably miniature ferrules or similar may be Occam's choice.] – Russell McMahon Apr 13 '15 at 14:45
Unfortunately I don't have the luxury of the space to do that. I have about 5mm between the enclosure and some oval surface pads that the wire has to be soldered to. The outer insulation must continue to the inside of the enclosure, and there is about 2mm of space between the surface of the pads and the base of the enclosure. Not a nice design at all, and I would have done it so differently had I been designing them. – Majenko Apr 13 '15 at 14:52
You can solder at least some versions of it. – Russell McMahon Apr 13 '15 at 17:19
I have found in tests that the best device for stripping the tinsel wire of this headset cord I have is to use the built-in wire stripping device (groove) that has developed over many years in one of my teeth. Once stripped a liberal amount of solder which also melts the insulation further back from the end seems to do the job. – Majenko Apr 13 '15 at 17:26
Long ago - when still living at home as a teenaager, I decided that using my teeth for wirestripping, which I did extensively, was liable to cause major damage long term, and I stopped doing it. About 6 months ago, for the first time in many decades, I simply held a wire in my teeth while I stripped the other end with side cutters. One of my front teeth fractured across diagonally and I had to have it rebuilt. I di enough other crazy things that I'll try to give that one a miss in future. – Russell McMahon Apr 13 '15 at 17:50

score 1 · Answer 2 · answered Apr 03 '15 at 18:42

I think what you are looking for is a cable for industrial control or sensing, maybe even a cable for robotics. A practical example would be a factory welding robot making the same kind of movements 24/7. The movements would probably include bending and twisting, all in a harsh environment. In these kind of applications moving cable chains and guides sometimes mitigates the problem of stress at the connectors.

I would suggest heading over to: http://lappusa.lappgroup.com/wire-cable.html Then checking if they are available to buy here (or similar): http://uk.rs-online.com

You also add some sort of coating on the PCB after the cable is soldered to the board. Electrolube and others manufacture conformal coating that is also removable.

You can read more about conformal coating here: http://en.wikipedia.org/wiki/Conformal_coating

score -1 · Answer 3 · edited Jan 14 '18 at 18:21

-1

Tinsel wire IME is aluminium and impossible to solder. A crimped ferrule is needed. Copper tinsel is often plated and after a few months becomes unsolderable, a problem well known in PCB manufacture where electroless plating is used.

EDIT: In Post Office days (later BT / British Telecom) this problem was known and soldering was not attempted the whole cable had to be replaced.Failures were not that common though.

Sorry, I just noticed this is an old thread.

edited Jan 14 '18 at 18:21

Transistor

168,990
12
186
385

answered Jan 14 '18 at 15:37

beerbug

85
2

This may do. http://cpc.farnell.com/unbranded/ccx-20kp/curly-stereo-extension-cable-flex/dp/AV01486?CMP=KNC-GUK-CPC-GEN-SHOPPING-UNBRANDED-AV01486&gross_price=true&mckv=s6xrrQ2Ra_dc|pcrid|224645119674|kword||match||plid||pid|AV01486|&gclid=Cj0KCQiAnOzSBRDGARIsAL-mUB2EU9Q-0tCft8L9Rg_Fp9MdqmhfXKHPFYy54YtQKKwiwWjTyN1A258aAm8VEALw_wcB it is copper not tinsel – beerbug Jan 14 '18 at 16:45
1

There's no need to comment on your own post. You can edit it to update or improve it. – Transistor Jan 14 '18 at 18:20

Wire for harsh environment

3 Answers3