Best way / options to wire to board?

[A-sic Enginerd]

Doing a board that will have a number of wires connecting. Most are just signal wires (on order of 5v), then there's mains.
In products, I've seen a gauntlet of connectors, terminal blocks, and even just solder a wire straight to a pad.

Personally, I hate the idea of soldering a wire straight to the board. I realize there are some pretty big advantages to doing that, but it just seems tacky to me (other than mains maybe). I've seen a number of connectors I like, but from what I've found they usually require some pricey hand tools to be able to make up a cable that mates to it. Terminal blocks are clean and make things more serviceable, but I'm leery of a reliable connection over time.

What are your thoughts / preferences for mains and / or signals?

And no, it's not practical in this case to have all things mount directly to the board. I did the best I could, but I'm still left with a few things that will have to be wired.

[Neilm]

You are right - there are many different types of connector.

Soldering to the board looks simple and will do if you are making a one off or something you don't mind going in to fix. However, there can be reliability issues with solder joints to wires. There are also safety issues. For instance, if you are making a product that has to comply wth IEC61010-1 (for instance multi-meters)  you are not allowed to solder mains wires to a PCB without the wire being mechanically restrained.

In high reliablility applications (for instance military) you are not allowed to have wires soldered to a board (unless it is a mod to that board).

For mains I would use (and have used) spade terminals. The crimp tool is reasonably cheap (£60) and will work with several different crimps.

Terminal blocks can be used, but I would not use them for anything long term unless I don't have a choice.

If this is for a product rather than a home project I would go with a good connector and either invest in crimp tools or find a company that will builid the looms for you.

Yours

Neil

[ejeffrey]

For signal wires, the easiest thing to do is to put the off-board elements on a separate PCB, put pin headers on both the main PCB and the daughter board and run a ribbon cable between them.  For something smaller, you can use flat-flex cable.

If you can't do that, use JST connectors or similar.  Cheap and easy.  They do require a crimp tool, but it isn't hard to come by.

For mains, I second the use of spade connectors -- make sure you get the shrouded kind.

[ciccio]

 

 However, there can be reliability issues with solder joints to wires. ........
In high reliablility applications (for instance military) you are not allowed to have wires soldered to a board (unless it is a mod to that board).

That is true, vibrations can cause the wire to break in the space between insulation and solder point.
There is a technique used in musical instruments (bass, guitar, keyboard) amplifiers, that have an high power speaker transmitting vibration to the PCB.
An example can be seen see in the attached image: drill a hole near the pad where the wire has to be soldered, and pass the wire trough this hole.
I was doing this years ago, and it worked (and it worked for more than 20 years)
I'm not sure that this will cost less than using wire-to-board connectors (JST are really cheap).

[Jon Chandler]

Single row headers and Amp IDC connectors make a reasonable solution.  The hand tool to punch down the wires is about $20, but the connectors are  less than 50 cents a piece so it's affordable.





One warning - the wire gauge must match the connector.  There's no leeway on this.  Some USB cables have larger power and ground conductors so you can't cut apart a USB cable and put one of these connectors on it.

There's a brief article here.