I'm not exactly a stranger to PCB design, but I've never been confident about the long term reliability of my wire to board connections. In the past, I've used Euro-style terminal blocks such as
It's no coincidence that both have a 0.1"/2.54mm pitch--I didn't want to have to redesign and reorder my PCB in the event that one connection wasn't that great. I found out about the former through building a JLM Audio kit and thinking the terminal blocks were pretty clever and simple, but I'm worried about oxidation and mechanical stress possibly being issues (although the latter really shouldn't be given that everything's going to be in a sealed box). The Molex headers seem to pull out too easily and don't seem to make very solid contact. Worse still, the crimp terminals are kind of annoying to crimp even with the proper tool.
What I'm looking for is something that will allow me to connect a few wires (say, from a panel mounted XLR jack for audio signals or a switch for digital inputs or something) to a particular place on the circuit board in a non-permanent but still stable way. I'm under the impression that it would probably be better to use PCB-mounted components for everything but still support the PCB in the enclosure through other means, but I'm just a guy with a center punch and a hand drill (and no 3D CAD software), so it would be tough for me to get everything to line up. What's the best I can do?
Suggest listing your requirements first: maximum current/pin, max voltage, vibration resistance, corrosion resistance, ease of
plugging/unplugging, max cost, max/min number of pins per connector...
No one connector is "best" without a concrete set of criteria to judge against, and there are literally hundreds of
0.1" connectors to choose from because of this, mainly variants of molex header and IDC style ribbon cable
connectors.
The molex connectors you mention are probably much better than you think - they are rated to 4A which implies
very good contact is made. If you want increased reliability consider gold-plated contacts for all connectors, this
really makes a difference in long term corrosion resistance. Molex style connectors are widely used so I think your
worries are misplaced.
I suppose 4A at 18VDC and 1A at 48VDC would be sufficient for almost all of my purposes. I'm not really sure how to quantify vibrational resistance, but there's a definite chance that some of my projects will end up mounted to a motorcycle. I'm a fan of modular systems, so it would be nice to be able to unplug/replug the connectors many times with no degradation in the electrical connection. I think I'll usually use 2-4 pins per connector--for PCB to PCB wiring where I need more pins, I'm satisfied with using a IDC connectors. I'm not married to the 0.1" pitch, but I like that it's reasonably economical in terms of space. In terms of the cost of part, cheaper is better, but my absolute price ceiling is probably around $7/connector. One additional criterion that I only briefly touched on in the original post is that I'd like something that's easy for me to assemble and is adaptable to a wide variety of wire gauges. Sometimes I'll be hacking up USB cables with 28AWG wire, most of the time I'll be using something like 20AWG, and sometimes I may want up to 16AWG. There are probably cases in my life where I might want to use up to 12AWG, but in those cases, I'll probably just go with PCB spades.
I'll reconsider my feelings towards the Molex connectors I've listed above, although I have seen them pull out before. Granted, the wire was being pulled slightly taught due to some misguided attempts at strain relief (not my doing), but I'd still prefer something that feels more solid. In the past, I've been hesitant to use gold plated contacts because I've heard in the audio world, the plating on frequently used phono plugs can eventually flake off and lead to worse electrical performance than nickel. Then again, I'm not going to be frequently plugging and unplugging these components once everything has been debugged, so I guess I don't have to worry about that.
Can also look into small screw terminals.
Digikey carries Phoenix screw terminals, I use 3.5mm pitch on this card to break out all the pins on a Mega/Due board.
Smaller are also available, but may not support the wire sizes you want - read their specs.
Another connector type is JST connectors, there are types availalble with a locking tab too.
Those are basically what I posted in the first link, although the manufacturer calls them "Eurostyle terminal blocks" or "Buchanan terminal blocks." As far as JST connectors go, I looked into them once, and they seem to only be available in 2 and 3 pin versions, but it's possible that I didn't look hard enough.
