4
\$\begingroup\$

I have a board with a Samtec SFM-115-L2-S-D-LC connector. This connector has 30 (15*2) pin holes, with a 0.050" / 1.27mm pitch, and accepts pins that are smaller than those used in breadboard / prototyping jumper wires. Therefore, I can't directly connect my prototyping jumper wires to the connector holes.

In the datasheet for the male version of my connector (TFM-something) I can see that the pins have a width of 0.018" / 0.46mm, while my jumper wires have the standard thickness (0.0254" / 0.65mm).

How can I connect individual pins/holes of my Samtec connector to, say, a breadboard? Are there jumper wires or headers with the appropriate thickness?

\$\endgroup\$
3
\$\begingroup\$

Yes there are headers you can use... like the Samtec TFM. A better option for hand soldering a breakout wire would be the Samtec FTS or FTSH (low profile vs standard profile), a plain 0.05" male header, in smd or through hole. It has some standard options and can be found through the typical distributors, Digikey, Mouser, etc.

If you want a standard or easily found part, your out of luck. Either use a header, or grab some appropriately sized wire an make your own cables by splicing the thin wire to some thicker wire, each side going to the corresponding board.

Another option would be to file the pin on your jumper wire down some with a piece of sand paper or a file. Even a nail file would work. Just rub it on it until the pin is thin enough to fit properly. Shouldn't take more than a minute per pin at worst. Alternatively slice some of the copper off with an exacto knife.

\$\endgroup\$
  • \$\begingroup\$ I'm marking this as accepted for now, but I hope someone comes along with a better solution :-) \$\endgroup\$ – Luís Marques Jan 5 '16 at 7:32
4
\$\begingroup\$

You can try using standard 24 AWG solid wire. This is the standard size used in solid-core CAT-5 Ethernet cable and is also one of the most common sizes used in the telephone industry. The nominal diameter is 0.020".

If the conductor is just that tiny bit too thick, try squeezing the conductor slightly with a pair of smooth-jaw pliers. It won't take much pressure to reduce the thickness by a couple of mils.

FWIW - I use 24 AWG solid-core wire for all of my breadboarding. It fits standard breadboards perfectly and is also a perfect fit in machine-pin IC sockets. You get huge amounts for free just by chatting with your local Telco guys.

One final tip: I normally cut the very end (tip) of the bare conductor at an angle using scissor-type cutters (Miller type 101 Wire strippers / cutters). This angled cut gives the conductor a taper which can make it much easier to push into a connector.

\$\endgroup\$
  • \$\begingroup\$ A piece of 25 pair cable will give some of each colour code colour, telco guys use a different numbering scheme, but the same colours as the resistor code. \$\endgroup\$ – Jasen Jan 5 '16 at 6:28
  • \$\begingroup\$ Thanks, that seems like it might also be a reasonable solution. I'll try it. \$\endgroup\$ – Luís Marques Jan 5 '16 at 7:44
  • \$\begingroup\$ I found some machine pin headers with a 18 mil diameter. Wouldn't those fit perfectly (individually)? proto-advantage.com/store/product_info.php?products_id=1900034 \$\endgroup\$ – Luís Marques Jan 5 '16 at 8:17
  • \$\begingroup\$ I ordered those, some other pins (correct pitch but thinner headers) and some pitch adapters. I'll see what works better. \$\endgroup\$ – Luís Marques Jan 5 '16 at 19:21
1
\$\begingroup\$

I think you may be out of luck here Luis. I've never seen them ready made and as you've noted, most ready made jumpers are for the more standard size of .0254", which also conveniently corresponds to 22 gauge wire, at least making it easy to roll your own. 0.018" corresponds most closely to 25 gauge (0.0179"), so you may have to search for a small roll of insulated wire in this thickness and make some of your own. Even there I was coming up dry looking for this guage in insulated wire. I did find some "Magnet Wire" with this guage on Amazon, at this link: TEMCo 25 AWG Copper Magnet Wire. But of course its insulation is a coating you'd need to remove at the ends to make jumpers, and at that thickness they'll be a little floppy.

The other possibility is to buy a few headers from the same company with matching pins, spend an afternoon soldering little wire loops to them (maybe with some of that more common insulated 22 guage wire), and later cut them apart. If you start with a single row header that will obviously be easier. Good luck.

\$\endgroup\$
  • \$\begingroup\$ Thank you for researching the specific wire. I'll see if the 24 gauge can be prodded into making the service, otherwise I'll try the 25 gauge one you mentioned or one of the other options from the other answers. The problem with the headers from Samtec is that their model variants confused me, and also when it came time to order IIRC it was "call us". "Hi, I'm calling about ordering a wire or two..." :-) \$\endgroup\$ – Luís Marques Jan 5 '16 at 7:49
  • \$\begingroup\$ And then there is the sad truth about measurements. Samtec probably at least has mechanical drawings you can download and get good numbers. I have a ton of samples from them because they have some of lowest profile header sockets I've ever seen, which is what I needed. I do find them a bit pricey though, even more then 3M whom I already thought was ridiculous. But my point is, Samtec seems pretty good about sample requests, and they don't cost a cent. :-) \$\endgroup\$ – Randy Jan 5 '16 at 21:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.