Nanofrog - It is clear this is a subject that you have done a lot more research on then I have but some of your statements goes against my own personal experience
Part of my job.
I am curious what you base that statement on, specifically the part that I highlighted?
Hence the use of crimp connectors in most automotive applications (vibration has caused soldered joints to fail in automotive applications)
It's not that a soldered joint is **** when done correctly, but that there are consistency problems associated with it (breakage due to vibration at the solid to stranded transition junction, corrosion [either due to moisture/chemicals, or from flux that remains due to a poor cleaning = remains active this way], cold joints [also breaks due to vibration], and a few others).
So the automotive companies worked with the electrical industry to find a solution, and they came up with crimp connectors and their respective tooling. Specifically, open barrel types (including later versions such as Weatherpack and Metripack) and non-insulated **** splices for automotive use (the insulation crimp is what makes these suitable for automotive use due to the strain relief provided by the insulation crimp).
As a result of all of this, most car makers made using crimp connectors company policy for electrical connections (separate from electronics). There's even legality issues, but I won't go into that (different specifications between automotive, aerospace, and marine applications found under MIL-Spec, DOT, DIN, ISO, CSA, TUV, ... types of regulated standards).
To give you a bit more information, here's a few sources.
I ask because I've worked on a lot of wiring in a lot of cars from all over the world and have never seen a factory installed crimp connector other then the ones used to terminate a line into a disconnect plug and to my knowledge, those plugs are used to simply to make assembly and servicing easier and faster.
Can you elaborate? Pictures would be ideal if possible.
Even in the instances I've seen a solder joint (one wire into two wire splice), it's part of a crimp as well (compression solder crimp; may or may not have adhesive lined heat shrink covering it, depending on vehicle age from what I've seen). For example, early '80's Jeep CJ's I've seen had this type connector (flat, not round), but no adhesive heat shrink over it, but rubberized adhesive tape instead (definitely factory). Wire strip length was quite long as well to be sure that the solder wasn't wicking up into the insulation.
As per using disconnects, it's definitely there to make production and service much easier and faster. But it was also chosen for the previously listed reasons vs. say a screw terminal to bare wire or insulation displacement connectors (cuts through insulation to make contact with the wire).
I can also tell you I never once saw a car come into our shop with a failed solder joint (and that's the only way we did it) but I could have made a small career out of fixing electrical connections made using other methods, including crimp connectors.
If the joint is done properly (sealed, and there's mechanical support), it would be fine.
Where you run into the issues with crimp connectors, is that the terminal, tooling (wrong die, insufficient location,...), or skill of the operator (location of the terminal in the die, incorrect pressure, strip length, ...) weren't correct for the application.
It may seem illogical, but keep in mind that in a production setting, those crimps are not usually created using traditional hand tools. They're either using electric or pneumatically operated with precise pressure control (can even include electronic monitoring, equivalent to tracking torque values for bolts and other fasteners), the dies are definitely the correct ones for the terminal being used (no "close enough" mentality), ... that give a consistent terminal each time. They even have to go in periodically to measure the dies for wear and replace them as necessary.
Quite a bit different from how they're done in the field. But it's not impossible to do in the field by any means (repairs, add-ons, or low volume production), but it does take some care to be sure to use the correct techniques (location positioning, strip length, proper insertion of the wire into the ferrule, ...) and tooling with the terminal being used. Not that hard, but the right tools and some practice to get it right is important. Otherwise, the crimp will be incorrect and fail (what I suspect you're seeing).
And in the case of the tooling for hand use, it can be fairly expensive to have a full range of tools (not all of them have interchangeable dies, or may not have every profile you need). Particularly if you're buying what was designed for and sold by the terminal manufacturer such as T&B, Molex, Panduit, ... vs. an inexpensive Taiwanese or Chinese tool in my experience (cheap stuff is a **** shoot, even for the ratcheting types in my experience).
Personally, I stick with
Pressmaster (specifically, the
MCT system for field use). BTW, they're the ODM for many terminal manufacturers, including Molex, T&B, Tyco, and NWS make at least some for Panduit (the other company I prefer to Knipex or Sargent as their die sets currently offered are too small/shrunk respectively).
I'm not keen on the non-ratcheting plier types either as it's too easy to be inconsistent on pressure (no compound jaw types, just that of a regular plier with typically 2 - 3 profiles ground in them). Too hard to get it right the first time IMHO (seen where it looks good, but when measured against specifications, it wasn't).
I would considering trying one of their 550 or 650 models but most reviews I read seem to indicate that their [Weller] quality has really fallen off in recent years?
Unfortunately, it has due to Cooper's more recent management decisions.
I've used Weller for years, and own a WD1001 personally (WD1 power head + WMP iron + WP80 iron), and they're not the same quality as older stations. Their newest line, the WX series, had to be recalled they were so bad.
For a home/DIY'er, I'd recommend a
Hakko FX-888 for those that live in the US (can be had off of Amazon for just over $80; pricing tends to get ugly in other parts of the world), and for professional use,
JBC.
- No sweat man. That suggestion was actually helpful because I've been wanting to get a good bench unit too!