To DIY'ers-how not to wire things

[joff]

Originally Posted by jkstill

Want the best of both worlds? Use some cheap bare crimps, and flow a little solder into it. You can get these at radio shack, and it makes it easier to make a good solder connection.

Actually, contrary to common sense, this is not the best of both worlds. Its identical to soldering only and has none of the benefits of the crimp. The only reason to favor a crimp connection is when temps are over 400F (solder melts) or when the wire is under tension/stress.

The copper/solder alloy is more brittle than the regular copper and doesn't bend much before it will fracture. Many non-engineers will fixate and overreact to this fact but the truth is it usually doesn't matter as none of the wires in our wiring harness are under significant stress. Vibration alone does not matter as the flexible wire before and after the joint flex before the solder/copper alloy flexes -- it needs to be high vibration and under tension in such a way that the joint "feels" like its being bent. For instance, voice coils in speakers are soldered and they are under extreme vibration -- BUT -- there is slack in the wire so the solder joint is not effected and there is no stress to the copper/solder.

When you crimp + solder, your crimped connection now contains the brittle solder/copper alloy. All you did was waste time and a perfectly good crimp on a soldered joint and you didn't even save any time.

[jkstill]

Originally Posted by joff

When you crimp + solder, your crimped connection now contains the brittle solder/copper alloy. All you did was waste time and a perfectly good crimp on a soldered joint and you didn't even save any time.

I appreciate the input. I've had a few years practice and do know how to solder.

The issue of not soldering a crimped joint doesn't seem that clearcut.

Here's a couple articles, one clearly against the practice, and one that tells how to properly do it. Granted, the second article is for larger wire than you will probably find in a car.

It may or may not apply to smaller wire.

http://www.ch601.org/resources/crimpsolder.htm

http://www.connex-electronics.com/?u...imp_guide.html

Personally, that's all the time I have to spend on looking up info on it.

Anyone else have anything?

[joff]

Originally Posted by jkstill

I appreciate the input. I've had a few years practice and do know how to solder.

The issue of not soldering a crimped joint doesn't seem that clearcut.

Here's a couple articles, one clearly against the practice, and one that tells how to properly do it.

Good info.

Yeah, I agree its definitely not clear-cut. :-) There are places for both.

I remember hearing NASA mostly uses crimp connections because anybody doing a solder joint has to be certified. A good crimp connection that is 99.9% the same as a solder joint is easy to make with the proper tool, proper hardware and proper prep and requires no skill (which is usually good for quality).

Being in the electronics industry though, its hard for me to imagine there being any question as to the reliability of soldering. We employ 3 full time soldering professionals for prototypes and repair work and have product lines with 20 years of production history and 100s of thousands of boards built so one can imagine the cumulative reliability data acquired. If there was anything wrong with solder joints, we would see it in our repair dept and in production yield stats and I'd be (as well as the rest of the industry) trying to find alternative ways to manufacture electronics.

Some further useful facts to contribute:

One of the biggest surprises to be learned about soldering is that rosin flux residue becomes corrosive at high temperatures. It is very important to clean the solder joint (acetone works best). It is not apparant immediately, but over the course of several years an invisible amount of flux can eat heat shrink, wire, and cause problems.

Also, the electronics industry recently got hit with B.S. (IMHO) Eco-legislation (RoHS) that requires us to take the lead out of solder. Soon it may become difficult for Joe Blow to get leaded solder which is superior in every way to the new "Greener" solder. Without the lead in solder, a phenomenon called "tin whiskers" causes solder joints to grow metal "hair" which can cause shorts to anything nearby. They take many years to grow such that the real hit to electronics reliability probably won't be known for 5-10 years. It also requires a hotter iron, easier to make a cold joint, doesn't flow as well, and is more expensive. It is also interesting to note that high reliability industries such as military and aerospace, have been given convenient exceptions to this new lead-free solder legislation.

[REVIT93RX7]

There are tools for every application. It is a matter of determining the environment one is using the wire in. Crimping will work is some applications and solder works for others. In the auto industry I think either one is fine. It just comes down to the skill of the person doing the work. Space I think is some cases dictates which method to use. Solid wire verse stranded wire is also an issue.