Better wire to board ideas? - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: June 20, 2013, 10:58:33 pm
content: Hi Everyone,So I've got this project that I connect some solid core ethernet wires directly to the board (6 connections). What I've been doing is using some through holes in the pcb, putting them through it, masking tape them down temporarily so they don't pull out, and then solder them. Then I end up putting the pcb in the enclosure it goes in which is a pain with this wire attached. You might be able to feel the tension in this process through my words, I really don't like the way this goes together currently. If I bend the cables too much, they will snap off, it is a pain.So, I've been trying to think of alternative methods.I've found a small block that you can install on the pcb that lets you push in a stripped wire, but it takes up a lot of pcb room and adds to the cost.Another idea is to drop the through holes and put some small square pads instead. Pretin them. Install the pcb into the enclosure without the attached cable. Then run the cable through and tack each of the 6 down to the pads.Any other ideas???

author: David_AVD
author_rank: Super Contributor
timestamp: June 20, 2013, 11:05:41 pm
content: Is an RJ12 (6P6C) connector not suitable?

author: asgard
author_rank: Regular Contributor
timestamp: June 20, 2013, 11:33:00 pm
content: If you really feel it necessary to direct-wire an ether connection then here's a way to mechanically protect it. If you have room on the PCB drill two holes just big enough to slip a cable-tie through. Make sure the join of the two ends of the tie is on the opposite side of the pcb, while the tie itself only touches the cable insulator. Built-in strain relief.

author: nctnico
author_rank: Super Contributor
timestamp: June 20, 2013, 11:59:19 pm
content: Wurth has several spring loaded contact blocks which aren't expensive.

author: peter.mitchell
author_rank: Super Contributor
timestamp: June 21, 2013, 09:20:57 am
content: Quote from: asgard on June 20, 2013, 11:33:00 pmLike this?

author: qno
author_rank: Frequent Contributor
timestamp: June 21, 2013, 12:23:04 pm
content: Last month i was at a tade show and picked up some samples from Zierick 5015 to 5054.This is and SMD wire clip with 2 pins that protrude the insulation.

author: asgard
author_rank: Regular Contributor
timestamp: June 21, 2013, 02:55:45 pm
content: Yes. That looks like it.

author: ejeffrey
author_rank: Super Contributor
timestamp: June 21, 2013, 04:38:35 pm
content: Another connector-less option: You can get PCB turrets: small posts that you solder to a through-hole. Some turrets are just posts you wrap a wire around and then solder, others have an eye that you can loop the wire through. You get a nice strong solder joint and you can solder the wire without access to the bottom side of the PCB.

author: alank2
author_rank: Super Contributor
timestamp: June 21, 2013, 06:30:06 pm
content: Lots of good ideas guys - thanks.

author: alank2
author_rank: Super Contributor
timestamp: August 14, 2014, 03:08:19 pm
content: Hi Everyone,Well, after trying a few things, I think I've come up with the technique I'm going to use. It seems to offer the most flexibility for the least trouble and price. I am going to use a simple through hole to put the wire through and then bend it flat against the board on the back side. I made the pad on the backside longer for the wire to bend flat against so it has more area to solder and will be held down by the solder. On the front side I am going to cable tie the cable down so the wire can't bend and break. Should be minimal work to do and no expense of any additional components.My last idea was a total pain, just having smd pads to solder to involved cutting the wires to just the right lengths and keeping them positioned with a clamp or tape while soldering and even then just not looking the way I wanted them to.Thanks,Alan

author: alank2
author_rank: Super Contributor
timestamp: January 20, 2015, 09:29:16 pm
content: I thought I'd post a follow up. I tried the previous msg technique and all it did was break the wires when I folded them tightly on the back side. I then tried plain old through holes and soldering from the top which works ok. I think in the end though the best technique might just be a smd pad pre-tinned like you would do to mount a smd resistor, etc. Just pre-tin the smd pads, then put the wire to it and heat the solder do it engulfs the wire. My mistake with this method before was trying to do 3 wires on a larger pad a time. From now on I'm going to dedicate a single pad so I can just hold the single wire to it and melt the solder...

author: ajb
author_rank: Super Contributor
timestamp: January 20, 2015, 09:40:58 pm
content: What about PC mount punch down terminals, which are specifically designed for thin solid core wire?

author: alank2
author_rank: Super Contributor
timestamp: January 20, 2015, 10:40:35 pm
content: Quote from: ajb on January 20, 2015, 09:40:58 pmLike a 110 block style thing? I'd love them if they were cheap...

author: Fsck
author_rank: Super Contributor
timestamp: January 20, 2015, 11:08:52 pm
content: Quote from: alank2 on January 20, 2015, 10:40:35 pmwhat was wrong with the typical screw down terminal blocks?or say a vertically oriented 8p8c. this is probably the best solution in terms of space efficiency + mechanical durability.

author: LabSpokane
author_rank: Super Contributor
timestamp: January 21, 2015, 12:17:46 am
content: Are you allowed to use better wire? Why can't you use a PC mount RJ-11 or RJ-45 block and crimp a proper connector onto the twisted pair? Those blocks are so ubiquitous that surely you could find an affordable solution.

author: alank2
author_rank: Super Contributor
timestamp: January 21, 2015, 12:22:37 am
content: Not enough room for a traditional type terminal block, or a rj11 or rj45. I'm using ethernet cable. I do use a cable tie to secure the cable to the pcb.

author: LabSpokane
author_rank: Super Contributor
timestamp: January 21, 2015, 02:29:05 am
content: Can you explain more about what you're trying to accomplish? What kinds of signals are you carrying? Is this a hobby or a commercial project? Are you building in quantity, or is this a one or two off deal? Is there a reason you are using CAT5/6 cable aside from the fact that it is available and cheap?

author: alank2
author_rank: Super Contributor
timestamp: January 21, 2015, 02:44:35 am
content: I use the cat5 because it is cheap just connected to some switches (practically no bandwidth necessary). The goals are (1) least amount of effort (2) cheap (3) reliable. I've tried ordering some push terminal blocks from Digikey that would work size wise thinking it might be worth the price, but I though I might be more concerned about getting the wire pushed in reliably vs. seeing it done by soldering it down. I think the bottom line is that I'm not going to get any cheaper or more solid than a smd pad for the wire.

author: LabSpokane
author_rank: Super Contributor
timestamp: January 21, 2015, 04:06:00 am
content: Cheaper? No. Lower profile? No, but close to it. More "solid" than 24ga wire soldered to pads ? There are many, better options. The solder inevitably creates a single flex point where the wire will eventually fail.Fine for a hobby project. Less fine for something you need to warranty. If it was my hobby project and I didn't want buy an expensive spool of cable, I'd be soldering Cat5 to pads just like you describe.Ribbon cable could be another alternative if the run is short.

author: alank2
author_rank: Super Contributor
timestamp: January 21, 2015, 04:09:14 am
content: Quote from: LabSpokane on January 21, 2015, 04:06:00 amAnything other than has already been suggested in this thread so far?Quote from: LabSpokane on January 21, 2015, 04:06:00 amIf the cable flexes right, but if it is held in place with a cable tie so it can't flex?

author: alank2
author_rank: Super Contributor
timestamp: January 21, 2015, 01:17:13 pm
content: evb149 those punch down connectors aren't bad at all!

author: dfmischler
author_rank: Frequent Contributor
timestamp: January 21, 2015, 04:04:47 pm
content: Perhaps one problem is that the wire is getting nicked when you are stripping it. That would create a weak point that could break when flexed.I have usedPhoenix screw terminal blocks like these. They make them with 2 up to 29 positions.You could put a header on the board and crimp connector terminals to the wire and stick them in a shell and plug the connector into the board.

author: DanielS
author_rank: Frequent Contributor
timestamp: January 21, 2015, 04:42:44 pm
content: Quote from: LabSpokane on January 21, 2015, 04:06:00 amJust about anything that mechanically restrains the conductors will eventually cause them to fail regardless of connection type if you give it enough vibration or other form of bending to get there. If you use cables to bridge two boards inside an application and tie it down properly should the cable be long or heavy enough to require additional support, dynamic stresses around the solder joints will be close to zero and the soldered connection will have indefinitely long lifespan.If you leave cables flapping in the wind, the wires will break, most likely near the connection points, regardless of what termination technique is used. Fancy connectors do not magically prevent this issue, that's why cables which might be vulnerable to vibrations are usually tied down and sometimes fitted with strain relief of some sort.

author: LabSpokane
author_rank: Super Contributor
timestamp: January 21, 2015, 07:08:42 pm
content: Quote from: DanielS on January 21, 2015, 04:42:44 pmHey, I'm with you. Is this was 18-20AWG, I'd have a different opinion. 24 AWG is pretty brittle after it's been soldered to a pad. Cat5 really is designed to be robust with the insulation left intact.I do realize that cables are solder terminated with 24awg and thinner all the time, but it gets done with fixturing and molded in strain reliefs and with insulation that's a lot more supple than cat5.

author: alank2
author_rank: Super Contributor
timestamp: February 24, 2016, 04:07:23 am
content: My quest for easy and cheap wire to board for my project goes on...I happened on to these:http://www.digikey.com/product-search/en/connectors-interconnects/solid-state-lighting-connectors/1443105?k=&pv28=2734&FV=fff40016%2Cfff80521&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25Why they are in the solid state lighting area instead of a general wire to board area I don't know, but they look interesting. Pretty cheap and you can slide a wire right on into place. Has anyone else used anything like this?