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About a year ago made a LED-studded glove from flexible LED strip (like https://www.sparkfun.com/products/12027 but without the silicon coating) for a party.

Because I wanted to keep some mobility in the hand, I cut the strip into smaller segments and soldered some ribbon cable in between with some flexing capability.

This worked for about half an hour, but then the connections started breaking. The solder joints themselves were fine, but the teeny-weeny stranded wires in the ribbon cable broke because of the strain. Taking the glove off broke several in one go.

Now I'd like to make a v.2 that would survive slightly longer. I'd also like to avoid soldering all the connections again because there are over a hundred connections to be made. Obviously, stress reduction is key.

If there was some very flat (1-2 mm) connector that I could just clamp on the of the LED strip and a suitable interconnect cable, that would be optimal. But I have no idea what to look for.

(I'm also open to better suggestions on how to implement the connections. I've considered conducting thread but the shortcut risk is too high)

EDIT: Turns out there are such connectors: http://www.aliexpress.com/store/product/free-shipping-10mm-4pin-for-5050-RGB-led-strip-light-LED-Connector/1027020_1544738051.html

Unfortunately I've only found the 2-pin and 4-pin variants, whereas my LED strip has 3 pads.

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2 Answers 2

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The key to reducing breakage for your project is to not rely on solder alone to hold down the wire. What type of wire were you using?

I am working on a similar project right now but more as a therapy glove and we are using a very nice flexible braided core wires. This type of wire with proper strain relief using flexible materiels providers a solid connection has stood up to much abuse.

As long as you are leaving plenty of extra wire between the modules with hot glue on top of the solder joint to provide some flexibility before it even begins to pill on the solder you will be fine.

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  • \$\begingroup\$ OP mentions that the solder joints survived but the cable conductors got fractured through repeated stress. \$\endgroup\$ Commented May 12, 2014 at 3:59
  • \$\begingroup\$ Thus my recommendation for wire and joint construction that can handle the strain. If you use the wrong type of wire no amount of strain relief will help. \$\endgroup\$ Commented May 12, 2014 at 4:18
  • \$\begingroup\$ Oh, I don't disagree with that. Just pointing out that the hot glue etc aren't central to the stated problem. \$\endgroup\$ Commented May 12, 2014 at 4:19
  • \$\begingroup\$ The cable was 5 wires from an old IDE ribbon cable; two of the wires were left unconnected and were there just for getting the spacing better. So probably something like 0.15 mm^2 or AWG ~26. Stranded. Do you have a reference for the braided core wires? Those sound interesting. \$\endgroup\$
    – lrasinen
    Commented May 12, 2014 at 17:32
  • \$\begingroup\$ This: electronicplus.com/content/… would work well (Part# 26BS). The key to strain reduction is to have as many parallel connections sharing the strain as well as flexibility in the connection. To handle the parallel connections make sure all wires are equal and attached to each other. Handling flexibility is tough, make sure you do not rely only on solder or crimped connections, those will break given enough movement. This is where hot glue is perfect, you can add it over the connection to allow it to flex and not break. \$\endgroup\$ Commented May 12, 2014 at 18:16
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You could go for some kind of FFC. Check for instance Molex Premo-Flex, they are available at Digikey

http://www.molex.com/molex/products/family?key=premoflex&channel=products&chanName=family&pageTitle=Introduction

The problem is you will have to match the pitch on your PCB with the cable somehow. Also I'm not sure this will work with a simple clamp. You would probably need to construct something which creates some kind of tension force.

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