I’ve seen these inexpensive cables on eBay for a while.
Bit the bullet and ordered one of each size.
At first glance, these looked reasonable.
After using them in several projects, the vote is in; these are the worst quality wire cabling I’ve ever used! (in 50 years) !
There is no problem with the crimp connection, the problem is with the cheap wire strands used in the wires.
A few flexes of the end of the wire where soldered to your PCB or a few more flexes of the wire somewhere along the wire length, the wire strands break.
The copper used in the strands is too brittle and end up breaking.
( Maybe aluminum with tin plating )
I had the same problem with a single dupont wire when soldering a switch.
No solder was accepted when tinning the wire, so I conclude that it is also aluminum wires.
None copper wires are a pain , but I have soldered those type successfully .
Any wire terminated into a PCB is likely to fail at that point if it’s continually flexed - unless it’s an “ extra flex” type cable designed for that purpose , but even that needs support .
A soldered junction is just that , if the there is any movement, the cable needs to be mechanically supported - eg cable tied to the board near the connection point .
Look at things like mains connectors which have a cable clamp to protect the connection point .
Another trick I've used with some success was to simply hot-glue the wires to the circuit board for mechanical strength. Don't overcoat the solder junction, just in case a resolder is needed, but simply glue the wires to the board at some convenient point. Looks like ^&*(, and more problematic if you want to boardswap, but then I'm not in industrial/commercial work, I'm working for my own entertainment in my own basement. YMMV.
Pro tip: when it comes time to undo anything you hot glued, isopropyl alcohol (the other IPA) turns hot glue into a friable cheese-like substance easily picked off with your Sorcerer's Pin.
I sometimes use a butane gas lighter for this purpose, however, then it is important to hold the shrink sleeve under the flame otherwise it becomes blackened with soot.
Interesting. I was wondering if, after crimping, the shape was regular enough to fit in a reasonably sized PCB hole (without having to be wildly oversized, that is). I have not actually used these myself in this application.
The wire is copper, it's just thin, probably of low quality - the stuff that goes into the ends and premade cables is typically worse than normal made in china wire, which is worse than domestic wire. Utter garbage.
The silicone insulated pre-crimped jumpers I've got were still like 4 AWG undersize. They all are. FEP wire does seem to be on target, for whatever reason (maybe the more difficult processing keeps out the riffraff?). I've gotten wire that was 8AWG undersize in PVC-insulated cable ends like that. They're crap. The dupont line, the problem is often the terminals (though some of the wire is horrible too - the ribbon cable is trash, as is anything that's magnetic, the best you can do on pre-crimped dupont starting from 1P jumpers or from individual wires (not ribbon cable) with terminals at the ends. There are 2 or 3 kinds of chinese knockoffs of harwin's original crap knockoff of DuPont's connector. The best kind of knockoff terminal, made in tin and gold surface treatment (when buying terminals, if you only buy the gold flash ones, you'll get these) is not much worse than Harwin's, though that connector attracted a lot of the same criticism as modern dupont connectors. The other two are horrible though, You can unfold them and flatten them into the flat sheet metal they were made from, and see the exact same pattern, just with slightly different dimensions, (particularly, shorter crimp area), and measure the thickness of the metal and see that the good ones are thicker. The worst of them is the type found on the ribbon cable. They have hair-thin wire, and ribbon cable dupont line always fails pull test.
Now, the wire breaking off when soldered straight to the board is NOT their fault. That is your fault - the very next thing you do after soldering on a wire to a pin is to glue it down with hotmelt glue or other fast-set adhesives. The solder wicks up the wire, then solidifies. Now there is a rigid structure making up the wire for a short distance, then an abrupt change to fully flexible; that is a stress point and the wire will fatigue and break shockingly fast. (also often complicated by the fact that part of the problem may be a weak solder joint (which you might add flux to and fix up once it was glued down and held in place by the glue so you don't need 3 hands), but the long wire, particularly once solder wicks up it, acts as a lever to more easily break the joint. (In tricky reqork cases, i someyimes alternately solder and glue, because ive broken off on wire in a cable being soldered to board while doing the others.
That's one of the advantages of using female -female cable and male board mount connectors when it's in a connector, and that often works better especially if wires may
There are various solutions to this seen in the field:
Wires + hotglue is very common in cheap crap.
Wires + adhesives of various other types is not uncommon. Silicone, some kind of godawful sticky waxy stuff, and some sort of super-glue like material.
Wires looped around the edge of the board and through a hole, or through a pair of holes where there isn't a nearby edge)
Wire-to-board pins and terminals Sometimes in consumer electronics one will find cables on which one end unplugs easily, and the other end, gee, it looks like a connector but it just doesn't budge. That's often a row of wires crimped to through-hole pins, in a housing soldered down. (Look inside a vcr or stereo thats being thrown out, about 50% of them have these ime - usually connector on one end and fake connector fornstrain relief on the other)
Typically the higher end stuff uses wire to board connector with actual connectors on both ends with a clear relationship between the quality of the connectors and how many digits the list price had. When you see something filled with wacky connectors that look expensive, dont be surprised when you get to thw single photon detector the crazy optics or some other wacky thing because the unidentified contraption you're disassembling is from a biotech lab, and cost somewhere between what a car and a house would, when it was new a couple decades ago. (Weve gotten to take apart a few things like that - a l9cal biotech startup got bought by a much larger company, and all their lab equipment wound up at the dump. Didnt get much of value from it, but damn, it was fascinating to look at the guts of. Sometimes youre disassembling something and its so well made you feel unworthy)
I often use UV glue to tack the wire securely to a surface.
After examining the wire strands under a microscope and doing some flex testing the wires are copper but have to conclude the copper strands is very poor quality.
The silicone wire discussed above with the 40AWG strands, i.e. huge number of strands, is simply the best .
Interesting, ill have to see if i can see what ypu mean when i get back to my base of opperations.ive got tons of shit wire to examine. What did you look for under the microscope?
Did you ever consider it worth the effort to figure out how many awg undersized it is (you need the number of strands twisted together, and a measurement of the diameter of one strand accurate to 0.01mm minimum (at .1, the uncertainty is too large). (The calculations are a PITFA, but ive got a setup in excel that i can just enter those in and get the actual awg)
Under magnification X70, I used a new scalpel and slowly scraped thru wire strands.
There was no silver/aluminum colour visible in doing this; meaning aluminum with electroplated copper was unlikely ?
After multiple wires that had a breaking issue, only copper scrapings were seen.
From this I concluded the strands must be solid copper.
However, there might be a possibility the strands are a poor alloy .
BTW I measured silicone insulated wire strands in 28AWG wire (made from 16 strands of 40 gauge), they all were around .003".
That is... surprisingly good to me, its closer than mosy, but measurement accuracy insufficient. 0.003 inch is about .075mm but it could be as thin as 0.0625, or as thick as .0875. (My spreadsheet uses metric inputs - this is because my calipers will give me inches to 0.001, but millimeters to 0.01, making metric units 2.54 times more accurate due to the measuring too, but also to sanity check listings. Sometimes they show an awg, and a metric stranding and claimed crosssectional area. Before buyi g any wire with those stats, i check it in my spreadsheet. If calculated from metric s t randing doesnt match the calculated metric area, the stats may all be completely bogus. Do not buy the wire. If the metric stats match, but the awg indicated its thicker, buy only if you want wire with the metric specs and the price is still fair - thats what youre getting, at best.
Sometimes the photos show a stripped end and are good enough that uou can just see visually "that aint 22 awg" and move on.
Anyway result from your numbers ranges between:
Thats a 2 to 1 difference in wire crossextional area and hence current carrying capacity. 16/0.0875mm stranding would give 27 awg. 16/0.0625 would be 30 awg. I think its safe to say that it is no larger than 28 awg. Question is just where it lies between 28 and 30 awg.
I also dont think there are 16 strands, i think you either missed or double counted one. They can only use certain numbers of strands, because that many strands need to be able to make a roundish bundle. Anyway - all im seeing on my chart up to 33 strands is thst the only ones ive gotten my hands on have 7, 11, 15, 17, 19, 21 - or they have more than 33 strands. Starting at 34, instead of every one being odd, every one is even. But my record of over 50 different types of wire contains not a single example of a wire with an even number of strands less than 34, nor off number of strands larger than 24
Wow. Unusual. I wonder if they use different stranding to help achieve thw well known flexibility.
And, wire and its thickness suddenly becomes a very interesting topic when a string of lights and controller you made fails and you examine it, thinking "wait, there should be a red and a black wire, why do i see two black wires. And then i noticed that yhe wires were hard and brittle. And when broken, one of the wires had a slight reddish tone to the black wire. An additional conector+lead was located stripped and measured. After a considerable ampount of pain figurong out the two wacky systems (this was when the spreadsheet was made, after doing two wires out by hand and being sure i had made a mistake) nope, no mistake, "22awg" i n sulation around 30 awg wire. I think some imof the heat came from the terrible inefficient buck converter it fed, which in this case happened to be below it). That was running in the living room of the house myself and three friends lived in! Sooooo after you see something like that, you disasseble all the strings you have, and start redoing the whole thing with better wire, better buck converters, etc.. the failure happened 2 years agp and i am still working on the replacement. Most strings are done, but the conttrol software also needs to be revised.....
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just rechecked the 28, 26, and 24AWG wires under microscope.