At last a sensible answer on this matter. Soldering in theory will always be a better bond. Trouble is, soldering properly requires skill, and I've seen lots of attempts at soldering by people who think it involves throwing some molten tin/lead at a couple of bits of wire and "glueing" them together. Crimping on the other hand de-skills the task. That's why such as wire- wrapping and crimping were developed many years ago, although the reason for use now is mechanisation of manufacture. A soldered joint will always be at least as good as a crimped joint, provided the soldering is done correctly and the crimp produces a proper cold weld. The unreliability then comes in the strain relief... but thats been said.
When I worked for Westland Aerospace the components like resistors and diodes on PCBs would have loops formed in the legs to help with strain relief. These components were in a carrier inside the input shaft of a helicopter gearbox and were potted too. I didn't see what they did with connectors though, that was done elsewhere.
On what type of cable? I stated earlier they work ok on solid core or stranded mains cable - just not on flexibles as used on cars.
I'd really suggest you make a few trial ones on car cables of various sizes then cut off the insulation and look at the result. A good crimp grips the cable all the way round - which requires a 'heart' shaped crimp formed by the tool. These are simply flattened.
The other thing is I dislike the look of them. They look like the bodge they are. The proper connectors as used by the makers of looms are easily available by mail order as are decent crimp tools. While I can accept a one off use by an amateur of these easily available crimps there's no excuse for pros using them.
Only crap ones. A decent crimp is airtight - which is why I dislike those red blue and yellow ones.
Snag with soldered connections is the wire is mechanically weakened either side of the solder. The PVC outer is also altered and will harden by the heat. But a well made solder joint is certainly preferable to a poorly made crimp. And without the correct expensive tool that's what you get.
Which is why proper car crimp terminals - of the type the makers use on the looms from the factory - include a crimp to the insulation after the crimp to the conductor. That's not to say this can't fail - it's common knowledge that a connector is the weak link in any chain. But that is the most reliable form around.
I always through those little wiggles were to space the component off the board rather than sit hard down on the surface. That's certainly why I used to do it if I had a resistor I knew was going to get warmer than I'd like.
Indeed - which is why it's unsuitable for a repair to a loom.
If jointing two cables where you have plenty spare, strip back about 30mm separate the cores into two lots, twist those from either cable first then twist the lot together. Then with a hot iron quickly solder only the last
5mm or so, using pliers as a heat sink to prevent the heat going up the cables. Then insulate with glue heatshrink sleeving. You'll then have a mechanically strong low resistance joint.
How do you think they join several wires together in wiring looms? Manufacturer's generally recommend looms be repaired in service, due to the uneconomical cost of replacing complete looms, although the germans hate repaired looms, and will always advise complete replacement.
But if you use the correct size that covers the wire you're joining, then it will provide a satisfactory crimp.
By using the 1/4" connectors that you've suggested, you've just put an extra joint into the loom. Not only that, but it's not a fully sealed connection. On a vehicle interior, it'll be fine, but on the exterior, water will get in. And if water can get in, it will corrode. On a power wire, it'll take a long time for the corrosion to become bad enough to cause problems, but on a sensor or CAN wire, it doesn't take much corrosion to cause problems. Also, if you join say 6 wires by putting in 1/4" terminals, one 1/4" terminal will take up the equivalent room of about 6 (probably more) wires, so instead of having a loom 6 wires big, you've got one equivalent to about
36 wires big. Off course you can stagger the connections, but they'll still take up alot of room, which is usually at a premium on modern vehicles, meaning you'll struggle to get trim panels back in place. The heat shrink butts don't add that much to the size of the loom in comparison, and only take up slightly more room than a soldered connection with heatshrink over it.
Well considering we've got several recovery lorries that had the original rear light looms (which lasted about 18months) repaired with heatshrink butts, and they're still working perfectly 4 years later, in what's about the worst enviroment for wiring on vehicles (fully exposed to road spray, with minimal support), you can't really say they're not upto the job.
All the pro crimp tools for RG&B pre-insulated terminals simply flatten the terminal - regardless of the pretty pattern they leave on the insulation. I'd suggest you actually examine the terminal crimp by removing the insulation.
Red pre-insulated are said to be suitable for 0.65 - 1.5mm² cable Blue 1.5 - 2.5mm² Yellow 3 - 6 mm²
BTW - I don't use junk crimping tools. They are pointless. The one I have for *proper* car terminals cost over 70 quid. Pre-insulated terminal crimpers - even decent ones - tend to be considerably cheaper due to economies of scale. The most expensive crimping tool I have for specialist small terminals cost over 200 quid.
No way can a 'flattening' crimp tool achieve a good crimp - the best you can hope for is a crimp that you can't just pull off with your fingers...
The other problem with the preinsulated types is that you can't see the actual crimp - I've seen many joints where the only electrical contact is where the connector has just about been squeezed so hard it pierces the insulation that it's crimped onto.
Yup. Pretty well all others produce a sort of heart shaped crimp - ie they indent the crimp to actually tighten its circumference. You need to do this to produce a gas tight seal over all of the conductor. A pre-insulated type cannot do this as it would pierce the insulation.
Yup again. I'd suggest those who think them ok cut off the insulation and examine the crimp. And compare to a properly made non insulated type. Chalk and cheese.
Not with those pre-insulated types I'm talking about certainly. Why would they use a 'universal' crimp in production when it's just as cheap - or even cheaper - to use the correct one?
Where have you seen a maker recommending those RB&Y crimps for loom repairs?
Care to explain how any crimp is air tight? With any crimp, unless in a fully sealed multiplug/junction box, or covered with self adhesive heatshrink, air is going to get into the wire/connector. And where air can get in, water can get in.
Most common ones I deal with are the ones that come with replacement advance solenoids for Bosch VP pumps, plus I've seen them mentioned in official loom repair guides. Manufacturers spec a watertight and mechanically sound repair, which heatshrink butts meet. Plus they offer the advantages of being quicker to fit, and being able to fit them in more inaccesible places than you can solder. Manufacturer's certainly don't advise adding in extra connectors.
These were a complete 360 degree loop. Probably a combination of vibration resistance and heat dissipation although, as I said they were potted as well. In a compound called X 11/49 if I recall correctly. It had the property that it would expand when setting and crushed the casing of a hybrid circuit that we were testing. That takes some doing as I couldn't even put a tiny dent in the casing with my bare hands.
Eww.. I guess that potting compound must have had redeeming features - I've only ever used ones that didn't expand at all.
Got bloody hot, though...
Were you making the hybrids, or buying them in? It all gets very strange working at that sort of scale - things melt and stick just from pressure, and you can barely see what you're working on, even with a microscope. And even then, ICs (hybrids just use the bare chips) don't look like they could possibly do anything, they're just covered in grey
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