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I feel a bit silly here. I managed to build a complex multi-board block of digital logic, but I can't figure out how to plug in a wire...

My plan was to buy a simple set of standard square-pin connectors, solder those to my PCB, and then connect to it with some ribbon cable. Well, I mean, I need 4 wires, so actual ribbon is maybe excessive. I thought I could just poke 4 separate wires on there.

Anyway, I purchased some 4-pin headers, and some 4-pin IDC plugs. Reading Wikipedia, I was under the impression that "IDC" means you just mash the wires in there and the blades are supposed to cut through the insulation, but... well, I can't get it to work at all.

I tried just smooshing the wire in there, but it easily falls out again. I tried pressing it down with the end of a screwdriver, but it still comes out, and the insulation is clearly still perfectly intact. Heck, I even tried stripping the ends of the wire and soldering it in there, but that didn't work either.

Am I supposed to use some kind of special tool to insert the wires or something?? How is this stuff meant to work?

The actual item in question is

https://uk.farnell.com/amp-te-connectivity/3-640440-4/housing-22awg-4way/dp/1098455

It plugs into the header just fine, but I can't figure out how to put wires into it. Supposedly it works with "AWG 22" wire, and the datasheet for my wire says it's "AWG 23", which I believe is meant to be thinner, so...

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  • \$\begingroup\$ Using a flat screwdriver will push the metal prongs out of the way, making it not displace the cable. Take a spare slim flat screwdriver and cut a slot into it. And grind down the tip to make it less pointy \$\endgroup\$
    – Passerby
    Commented Aug 31, 2018 at 18:01
  • \$\begingroup\$ Like this instructables.com/id/Leatherman-Punchdown-Tool or get a generic punch down tool at home depot or whatever. \$\endgroup\$
    – Passerby
    Commented Aug 31, 2018 at 18:10
  • \$\begingroup\$ if you view the 3D model on the farnell website, you will see that each contact has two pairs of blades that cut through the insulation ..... you need to press the wire in three places ..... you could use two small bladed screwdrivers to push down on either side of each contact blade \$\endgroup\$
    – jsotola
    Commented Sep 1, 2018 at 2:51

2 Answers 2

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Yes, for this particular type of connector you need a special tool, like a screwdriver blade with two cuts. Something like this one:

enter image description here

Here is a home-made punch tool, using a flat-blade screwdriver and Dremel with thin diamond cut wheel:

enter image description here

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  • \$\begingroup\$ So, a punch down tool. \$\endgroup\$
    – Passerby
    Commented Aug 31, 2018 at 17:50
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    \$\begingroup\$ Geez they want 25 bucks for that piece of plastic. \$\endgroup\$
    – Passerby
    Commented Aug 31, 2018 at 17:56
  • \$\begingroup\$ Interesting. I see several of these things for sale. Any idea how to determine which one(s) will work with my particular part? Are they more or less standard, or all manufacturer-specific? \$\endgroup\$
    – MathematicalOrchid
    Commented Aug 31, 2018 at 18:10
  • \$\begingroup\$ @MathematicalOrchid, Yes, the tools are connector specific. I usually make the "punch down tool" (thanks Passerby) out of a freely available and cheap screwdriver. I make cuts in its blade using Dremel tool with thin diamond cut-off disk. Works fine for me. \$\endgroup\$
    – Ale..chenski
    Commented Aug 31, 2018 at 18:15
  • \$\begingroup\$ 25$ that's cheap, harwin makes an extraction tool that is 60$ for a modified IC puller newark.com/harwin/t5746/connector-separator-tool/dp/01E9678 \$\endgroup\$
    – Voltage Spike ♦
    Commented Aug 31, 2018 at 18:36
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IDC connectors require the wire to be pushed down firmly on both sides of the contact blades. Trying to push them by hand or with an inappropriate tool will often just result in the wire bending out of the way.

Different types of connector handle this differently.

The most common type of ribbon cables and connectors uses double row connectors with a 0.1 inch (2.54 mm) pitch on the connector and a 0.05 inch (1.27 mm)pitch on the cable. On these connectors the lid of the connector acts as a die. You put the cable in the connector and then squish the lid down with a vise (special tools are available but I've found the cheap ones at least are worse than a cheap vise).

Your connector however is a single row connector designed to be used with either single wires, or a larger 0.1 inch pitch ribbon cable and appears to need a tool to push the wires down.

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