Female JST connector for PCB mount

[dgrz]

I've designed a small PCB for controlling a WLED-driven set of Halloween costumes for the family. It's working very well, but I've been soldering BTF-Lighting JST pigtails onto the PCB and the strain on the solder joints / wires are a weak spot. I have been trying to find an appropriate 3-pin through hole female connector, but can't seem to find one that fits. Does anyone know which JST variant would be appropriate?

Thanks!

[ajb]

I don't think there is one, and if there were it would have to be pretty tall to accommodate the latch. 

You have some options for making the soldered wire-to-board connection much better.  The key is to make sure that the solder joint isn't what's taking the mechanical load.  If you extended the PCB out from where the holes are, you could place two 3-4mm holes either side of the wires and run a zip tie around the wire + PCB via the holes.  Make it nice and tight, you should see the insulation compress a bit, so that the zip tie is what's keeping the wire in place, not the solder.  You may want to run the wires through a bit of heatshrink tubing to provide additional strain relief.  You may be able to approximate this method on your current boards by folding the wire around the edge of the board towards the back, then wrapping a zip tie around the whole lot. 

If you need more secure grip you can run the wires up and down through a couple of holes in the PCB before soldering, but that's a pain to assemble. 

[dgrz]

I don't think there is one, and if there were it would have to be pretty tall to accommodate the latch.

I hadn't even considered that option, but that does make sense! 

You have some options for making the soldered wire-to-board connection much better.  The key is to make sure that the solder joint isn't what's taking the mechanical load.  If you extended the PCB out from where the holes are, you could place two 3-4mm holes either side of the wires and run a zip tie around the wire + PCB via the holes.  Make it nice and tight, you should see the insulation compress a bit, so that the zip tie is what's keeping the wire in place, not the solder.  You may want to run the wires through a bit of heatshrink tubing to provide additional strain relief.  You may be able to approximate this method on your current boards by folding the wire around the edge of the board towards the back, then wrapping a zip tie around the whole lot.

Thanks for the suggestions! I think I'll also see if I can use a more standard JST connector on the PCB and simply make an adapter from JST to the BTF variant...

[tooki]

I looked into this a while back, and it doesn’t exist. That’s the JST SM connector (I sure do wish people would stop calling all of JST’s product by brand only, since they make dozens of connector families!), and it has no board-mount counterpart. However, SM female connectors with just a few pins will fit onto normal headers, and if you really want a nicer fit, the JST NH headers are designed to mate with the same contacts. (NH female and SM female use the same crimp contacts, just in a different housing.)

I’d either use NH headers, or just solder WAGO (or similar) spring terminals onto the PCB and insert the stripped wires directly into that — it’ll be much more reliable than soldering stranded wire directly into a PCB. WAGO 233-503 is 2.54mm pitch, but if you need a lower profile connector (at the expense of larger pitch), look at, for example, 2086-1223, and lower still, 2060-473.

[dgrz]

Thank you. Those Wago connectors look nice - I'll order some and check them out!

[coromonadalix]

put the pcb in a small  longer box

make a small slot for the cable but be sure when closing the enclosure, it will lock the wires and kept them from moving


the design should have taken this into account, longer pcb with added holes to keep the wires secure ??  a learning process for a next iteration

[wraper]

There is a large problem with making female PCB connectors and that's why you don't see them that often. Springy female contacts are made out of thin metal. It works perfectly on wire side as it also allows crimping. However on PCB side it makes connector mechanically weak if electrical contacts are the only thing that holds it in place. And then you have another problem on wire side since you need thicker prong that does not get easily bent but it need to be crimped too which requires thin metal. So male wire side connector prongs are usually made out of thin metal that is folded into prong shape. It makes them much weaker than normal prongs on PCB side made of solid piece of metal.

[markietas]

"I sure do wish people would stop calling all of JST’s product by brand only, since they make dozens of connector families!"

Preach!!

JST, Molex, Ect... Literally thousands if not more different connectors you could be talking about. Drives me up the wall, the drone community is particularly bad about it except with XT-x series for some reason.

[tooki]

Yes, the drone community’s terrible usage has not escaped my observation, either.

And of course then there’s the awful way that “DuPont” has become a generic term for any 0.1” header product, and to some extent, a synonym for any crimp connector at all. :/