Yes, same Maine SailFYI
The best wire termination info I have found:
Making Your Own Battery Cables - Marine How To
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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
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.Who gets to make the call on what portion of a wire is required to remain flexible?
I'm not saying the spec is wrong. I just know I don't have to worry about any of that if I make a proper crimp.
Sure.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.
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.Ultrasonic fused? Good question, probably something involving lots of gold I would guess.
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.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?
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.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.
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?
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'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.
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.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
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.But nothing wets and flows so nice as 60-40 solder... I will stick with lead as much as possible.
Chemistry was never my thing,
But I thought it was absence of halide ions in flux primarily credited to inhibit dendrite growth.
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.I was comparing vibration and g-force but in the end I was saying we still need to be careful about soldering and wicking because there are still vibrations and forces on the wiring.