Electronics > Projects, Designs, and Technical Stuff

Your Experience with Reliable Connections?

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Wendy_Preston:

--- Quote from: Mr. Scram on August 07, 2020, 04:03:21 pm ---
--- Quote from: Wendy_Preston on August 07, 2020, 07:20:00 am ---Now, please don't blast me for mentioning our own company's connectors - but high-reliability is kind of our bread-and-butter. We supplied Datamate connectors to NASA for the Robonaut...

https://www.harwin.com/connectors-hardware/high-reliability-connectors/

On a more general basis, I'd say you need to consider at least the following features:

* Some sort of fixing between mated pairs. Jackscrews, screw-loks, bayonet locks, latching - something. This will prevent the vibrating apart. Depending on how often you need to disconnect the pair will help you with your choice of fixing feature and how quick or easy it is.

* Backpotting, cable hoods, heatshrink - some form of additional strain relief on the cables at the rear of the connector. This is one of the more vulnerable spots over long-term vibration. As elsewhere mentioned as well, make sure there is a bit of slack in the cable loom - but not too much that it's flapping around.

* On that note, consider cable management near the connection, like cable tying it to a fixed part so it vibrates with the rest of the build rather than against it.Other solutions are available  ;)

--- End quote ---
Not to hijack this thread, but are those Gecko connectors suitable for board to board connections too?

--- End quote ---

Sorry for not replying on here earlier Mr Scram, but I'm only on once a week, apologies! And yes, Gecko is definitely suitable for board-to-board. We have applicable options with both latches and screw-loks. If you need to disconnect them at any time, latches will need side access (to reach in and press the latches), screw-loks will need rear access to unscrew. Both styles are tested for vibration and shock.

If you need any help with these, do please reach out to one of our Technical Experts!


--- Quote from: Alaezae on August 07, 2020, 08:58:07 pm ---I looked at the Harwin Connectors, I like them. Definitely expensive at $20 for one of those circular connectors, but certainly in problematic areas it is something to consider. Thanks for everyone’s help, I think the main thing is mechanical support and some sort of lock. I’m still going to try and avoid solder. Thanks!

--- End quote ---

Unfortunately Alaezae, yes, they are not the cheapest connectors on the market - they are priced to reflect the processes, development, higher level of test & inspection and quality materials that we need to utilise to make a micro-connector withstand the environments that it does. There are more expensive options available too ;D. But seriously, we find our connectors have good traction in larger companies with planes, racing cars, medical or other vibration issues - for hobbyists and start-ups, it might not be an option unless other lower-priced options have already failed.

cmcraeslo:
Soldered wire-to-board connections work perfectly (tested in real life in various rough environments for many years, but have not gone to space with them). Trick is to use long enough wires so they don't stress the boards/joints and properly fix them on the board somewhere, so the only thing moving/stressing the joint is the weight of the wire from fixting point and the joint (leaded). If you have such vibrations that this method fails, then you the connectors will be the least of your worries.

If you use modules that are constantly plugging/unplugging, make them with integrated wires and use a wire-to-wire connector like automotive Amphenol ATM series. We use it like that and hadnt had a failure due to the wiring.

max_torque:

--- Quote from: cmcraeslo on August 17, 2020, 09:40:37 am ---Soldered wire-to-board connections work perfectly (tested in real life in various rough environments for many years, but have not gone to space with them). Trick is to use long enough wires so they don't stress the boards/joints and properly fix them on the board somewhere, so the only thing moving/stressing the joint is the weight of the wire from fixting point and the joint (leaded). If you have such vibrations that this method fails, then you the connectors will be the least of your worries.

If you use modules that are constantly plugging/unplugging, make them with integrated wires and use a wire-to-wire connector like automotive Amphenol ATM series. We use it like that and hadnt had a failure due to the wiring.

--- End quote ---

Directly soldering wires to a pcb is a real no-no unless you can absolutely anchour the wire to the pcb independantly of the solder joint!   What i have found works is two plain holes through which the wire is threaded like a snake and then soldered to a surface mount pad, or poked into a plated through hole and soldered.  Here it is critical that only just enough solder is used to anchour the conductor to the PTH, but not so much that the solder wicks up the wire!  ANY solder in any bit of unsurpported wire that can flex in any way WILL result in a very early life failure.

With the "wire snaked though the pcb first" trick, you can also use an adhesive to  help retain the wire to the pcb, and if necessary, also probide a second set of holes through which to thread a zip tie to strain relieve the wire bundle.

All of this takes up a fair bit of pcb real-estate of course

RJSV:
Datamate Connectors, (seen in recent posts), even three of those, what quantity could you use up, in six months, or worse: how many failures are OK, in six months, say?
 
  I did testing, Systron Donner, Concord, CA.  Any failure could have disabled an engine fire detection!
Or, less bad, cause a false alarm, turn the airliner back to airport. Yeah, I guess I got attitude, with safety issues.
  Map your failures, aggravation. What if some key Engineers QUIT, over that. If it was a good subject to ask, then try spend that, out. Just monitor things.

  Can connectors be changed, with later package ?
Or is this a less formal setting ? My job, got pretty up-tight, with 379 $ for one, Mil-spec 9 pin conn.

cmcraeslo:

--- Quote from: max_torque on August 17, 2020, 11:36:04 am ---Directly soldering wires to a pcb is a real no-no unless you can absolutely anchour the wire to the pcb independantly of the solder joint!   What i have found works is two plain holes through which the wire is threaded like a snake and then soldered to a surface mount pad, or poked into a plated through hole and soldered.  Here it is critical that only just enough solder is used to anchour the conductor to the PTH, but not so much that the solder wicks up the wire!  ANY solder in any bit of unsurpported wire that can flex in any way WILL result in a very early life failure.

With the "wire snaked though the pcb first" trick, you can also use an adhesive to  help retain the wire to the pcb, and if necessary, also probide a second set of holes through which to thread a zip tie to strain relieve the wire bundle.

All of this takes up a fair bit of pcb real-estate of course

--- End quote ---

Exactly. This works great in real life (tested this method in all kind of motorsport applications and hadn't had a failure). Using fancy connectors with incorrect tools for crimping the cables, brings a lot more trouble than this method.

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