Connectors and crimpers
- Thread starter Photobug
- Start date
Yes, same Maine SailFYI
The best wire termination info I have found:
Making Your Own Battery Cables - Marine How To
Pick Your Crimp Tool FTZ 94284 & Ancor Hammer Crimper TEMCO TH0005 & FTZ Bench Mount BUY FTZ 94284 CRIMP TOOL - BAY MARINEmarinehowto.com
Marine Wire Termination - Marine How To
Marine Wire Termination - Tools of the Trade MHT Recommended Tools: The products below are our top picks for crimp tools. RecommendationsI include; PRO GRADE, MARINE GRADE, & PENNY SAVER GRADE. Every tool recommended BELOW, we have tested here.marinehowto.com
People can of course do whatever they like on their own rigs.
No need to keep arguing against what others recommend about best practices.
You would not believe the things that fly under yhe "done this way for decades never had a problem" flag.
DaveInDenver
Middle Income Semi-Redneck
You still have to worry about flex with crimps, just that you don't have to worry about the terminations causing additional issues with stiffness and the stress concentration at the transition from solid to stranded.
What is an acceptable amount of flexure depends on the cable type (strands, copper composition), bundling, insulation type (plus new variables with heat and chemical reactions from the wicking), radius tightness, environmental factors like temperature or vibration frequency. IPC doesn't specify this because minimum acceptable criteria here is not a workmanship question, it's a requirements question.
If you can't be sure that wicking under insulation has not occurred you probably should support the cable with a backshell, strain relief or just hold it fast with a wire tie back to an unaffected stranded section. But the reality is we're not talking about Mars rovers, so it's not that important.
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shade
Well-known member
Sure.
I meant that there's another example of how there's a relatively simple recipe for a good crimp compared to doing the same job with solder correctly.
Speaking of Mars rovers, what type of terminations do they use on that kind of equipment?
shade
Well-known member
Ultrasonic welding is one of those gee-whiz techs that is just darn cool. I think I first stumbled onto it when trying to figure out how some plastic thing was made that I wanted to repair.
DaveInDenver
Middle Income Semi-Redneck
I personally never worked on the rovers but have worked on 11 programs that made it to their orbits (one is around Mars), one that is a deep space probe and one that got a ride on a vehicle that failed on launch (now sits at the bottom of the Pacific). Every cable used crimped terminals. Gold is pretty typical of mating surfaces. Crimping has an additional benefit since even stuff that leaves the Earth has to adhere to RoHS so not having to deal with lead-free solder is a benefit. The substitute for lead solder is a tin-based solder that likes to grow dendrites due to electro migration and create micro-shorts. It'll even grow through conformal coating on PCBAs.
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shade
Well-known member
I've read about that. Seems like an issue that will slowly rear its head as older tech that reached the point of "good enough" stays in service longer and longer.
Space-grade D subminiature, micro D, and circular connectors, chosen based on application and packaging.
As Dave said above, it's crimped connections wherever possible, which is as it should be for any serious/OEM application. (Definitely no "crimp-then-solder".) All use machined circular contacts, crimped with 4 indent/8 impression tools per M22520/1 and /2, rather than the open-barrel types common with volume production OEMs.
Where there is no crimp option, soldered connectors are used... in particular some user-terminatable small connectors have no crimp option, so solder it is, with very stringent training and inspection processes. But they'd def crimp 'em if they could!
DaveInDenver
Middle Income Semi-Redneck
Talking about tin whiskers, it's kind of an odd one. It's actually not a new problem but goes back to the early days of electronics. They are usually tiny hairs so typically they've just burned up but it's become a serious problem in the past 20 or so years because the switching voltages and currents have gotten so low that they don't vaporize like they did. The whiskers also cause issues as switching frequencies go up as the length of a stub that's just a couple of mm long affects the circuit tuning. At 10 GHz a whisker 7 mm long is actually a 1/4 λ antenna. Mitigating the phenomenon is why lead was put into solder in the first place. Tin and zinc are better conductors, so it's kind of a problem we knew but forgot about.
I too have had to solder due to not having a good crimp tool so that's something I do need to invest in. Sure we are not subjecting our wiring to rocket launch stress but engine vibrations and/or lots of bumpy roads can flex wires a bit so one should be careful to not let the solder wick out of the crimp as it can make the wire stiff and more likely to break.
I prefer to keep consistent with whats in the vehicle as my own best practice so currently I try to stick with mertr-pak since thats what my current truck uses. This way my tool/spares kit for my own additions works as a vehicle tool/spares kit as well.
One thing I did learn myself is that most automotive connectors, being intended to be under a hood or inside a cabin or under a body, are not designed to be UV safe. I'm having to redo my CB antenna setup currently because the current connector insulation and heat shrink have sun rotted and are flaking off after 10 years of sun exposure.
I prefer to keep consistent with whats in the vehicle as my own best practice so currently I try to stick with mertr-pak since thats what my current truck uses. This way my tool/spares kit for my own additions works as a vehicle tool/spares kit as well.
One thing I did learn myself is that most automotive connectors, being intended to be under a hood or inside a cabin or under a body, are not designed to be UV safe. I'm having to redo my CB antenna setup currently because the current connector insulation and heat shrink have sun rotted and are flaking off after 10 years of sun exposure.
DaveInDenver
Middle Income Semi-Redneck
Don't underestimate it, automotive environments can be amongst the most harsh for component manufacturers to meet. Just take the typical electronic component temperature ranges.
- Standard Commercial: 0°C to +70°C
- Standard Industrial: -20°C to +85°C
- Extended Industrial: -40° to +85°C
- Standard Automotive: -40°C to +125°C
- Military and Aerospace: -55°C to +125°C
The car companies have their own system and the published AEC-Q100 (Automotive Electronics Council) grades can be harsh. The design grades are applied based on several things, high or low under the hood, where on the chassis, inside or outside the passenger cabin, etc.
- Grade 4: 0°C to +70°C
- Grade 3: -40°C to +85°C
- Grade 2: -40°C to +105°C
- Grade 1: -40°C to +125°C
- Grade 0: -40°C to +150°C
Most component manufacturers consider automotive as a high reliability application also with respect to vibration and shock. When you think about it even just a plain passenger vehicle is very hot under the hood, might be used in the arctic, the desert, low and high elevation while being pretty sure it's not going to fail at 75 MPH or in a year.
Nevermind commercial and utility users aren't usually buying military vehicles and aren't necessarily refitting from the ground up. So a humble F350 off the lot has to meet fairly high reliability requirements by design. They usually just lack the ultra low temperature range and won't have the same radiation requirements.
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DaveInDenver
Middle Income Semi-Redneck
Kester 44 (63/37 eutectic) for the win! In 2021 using it pretty much guarantees you'll meet no requirements anywhere. But it melts like butter and flows smooth like Velveeta. You could probably use a Bic lighter and still not end up with cold solder joints.
DaveInDenver
Middle Income Semi-Redneck
Yup. It's just easiest to illustrate that automotive approaches military specs with temperature ranges. But yes, a big reason crimps are preferred over soldering is mechanical and how you deal with the transition from relatively flexible wire to a fastened terminal. Solder wicking up the conductor makes an abrupt transition that can vary with workmanship while crimping is easier to validate and highly repeatable.