Re: Off season skills: Learn how to Solder
 

A cold solder joint results when the wire hasn't been heated up enough for the solder - you can melt the solder because the iron is hot, but it won't adhere to the wire properly if the wire is too cold. The most common way I've seen this done from my students is to put the solder directly on the iron, then touch the iron to the wire. It appears to work quicker, as the solder melts immediately and then is transferred to the wire... but the solder can then be pulled off very easily as it's mostly just sitting on the surface.

That's why it's important to always put the iron on the wire first, then feed the solder into the wire, not the iron. It takes a bit longer than the "easy" way, but you're guaranteed a good joint, and you can actually watch the solder flow through and all the way around a stranded wire.

That's also why working with lead solder is easier... the lower melting point of lead makes it easier and quicker to get the wire to the correct temperature for that solder.

Re: Off season skills: Learn how to Solder
 

The "lead free" solder bashing is dumb. Let me harken back to the years of heating an iron with an external source, putting flux on the joint with a small brush and then heating it with the now hot iron, waiting the right amount of time and adding solder to seal the joint.

Purpose of classes is to TEACH people how to do it right. Right tools, right skills, right training, learning how to do it right.

Sorry you don't have an iron that reaches the right temperature, sorry that you didn't buy solder that has the right mixture of flux and metal. Sorry that you didn't learn to heat the joint first, then apply solder. Sorry you didn't learn to clean the tip and reflux/re-tin it every so often between joints.

And I can carry the "sorry parade" to other items: drills, saws, punches, welders, 3D printers, flux-capacitors, photon-tubes,warp coils, Transmogrifiers, and of course the center of all IFI and Andy/Mark parts, unobtainium.

Mostly sorry that I keep forgetting that CD is a whine fest of people that can't pull together the right skills :rolleyes: while most of us go "Ok, that didn't have a happy ending, how do I fix that." Lead free solder is here, deal with it.

Re: Off season skills: Learn how to Solder
 

My first post was not clear. I'm not trying to say that lead free solder can not be used well, but that it is much harder to have a high school student who has never seen a soldering iron before do a good joint with lead free solder. If you take the time, it is definitely possible to cause the lead free solder to flow and make a good connection. But it is very easy for an inexperienced student to just get the solder to form into a cold solder blob.

Also, in commercial electronics it is a proven fact that lead free solder is inferior and has a significantly higher rate of failure.

Re: Off season skills: Learn how to Solder
 

Bigger joints, like the ones used to mount wires on Banebots. I don't know how other teams do it, but our joints are pretty heavy duty. We don't do too many small joints, as we have plenty of adapters and splitter cables from previous seasons.

Congratulations on winning at IRI:)
Couldn't agree with sanddrag more. Leaded solder has a lower melting temperature, meaning the iron will take less wear when using it. This is because metal has a tendency to oxidize faster at higher temperatures. Tin is brittle and weak(for a metal), while lead is malleable and holds to itself very well. This is why an iron in storage will be preserved better if it is tinned using Leaded solder. If you are using the iron and solder properly, Leaded solder is no more dangerous than lead-free. As long as you don't set your iron above 600F or so, the fumes from lead solder will be all flux.

efoote, I have never heard of soldering the anderson connectors. We have a special set of crimpers designed for powerpoles and, when used properly, they work extremely well.

Re: Off season skills: Learn how to Solder
 

That is true that the heat of the xbox/ps3 doesn't cause the solder joints to fail, but the misconfiguration of the BGA soldering machines which caused the lead free solder joints to be cold and fail early. Same issue as some Macbooks had with Nvida integrated GPUs a while ago.

Re: Off season skills: Learn how to Solder
 

I had a Vex Cortex controller fail due to what appears to be a poor lead-free solder joint. The stuff just does not flow the same.

Re: Off season skills: Learn how to Solder
 

Jim,
We solder all joints. Not that they need it but we lost a World Championship to Beatty a long time ago because one of our crimps let go. We even solder the battery terminals.
There is an interesting NASA study done on lead free solders, printed a few years back. They found that the lead free grows conductive crystals with time and eventually short out adjacent circuitry on printed circuit boards. I have been careful to watch for that in my day job and have found hundreds of failed joints and shorted traces over the years. But lead solder also has failures, most often in temperature control. I just replaced a main relay in my daughter's Honda for defective joints.

Re: Off season skills: Learn how to Solder
 

*cough2001* I can imagine that the terminals used now are much more robust, though. Our electrical mentor told us about how his company normally uses lead-free solder, but they have to use leaded solder in products shipped to the middle east because they found that the dust and smog causes lead-free solder to grow crystals like you described.

Re: Off season skills: Learn how to Solder
 

No, the insulation itself contains small amouts of lead. I know an electrician who used to chew on the insulation from THHN, he got lead poinsining that way.

A properly crimped joint is superior to an uncrimped but soldered one.

But in FRC most teams don't know how, or don't have the tools, to do it "properly". So, crimp then solder. Just don't wick solder up the stranded wire, this causes it to become stiff like solid wire and break more easily.

Re: Off season skills: Learn how to Solder
 

Along with a lot of other nasty stuff to keep the smoke down, limit flames, stabilize the plastics. Yuch!

Re: Off season skills: Learn how to Solder
 

I'll point out that immediately after saying that "lead free solder bashing is dumb", you go on to point out several reasons why using lead free solder is more difficult than using leaded solder. I agree with all of your reasons why it is easier to learn soldering using leaded solder. In my experience having a positive first exposure to any skill set will likely lead a student to want to continue exploring and learning in that area, so therefore I would heartily agree with the recommendation to use leaded solder when teaching introductory electronics.

At least that is the purpose of my clasess... teaching electronics... and if I can get students to focus on the electronics and to have a positive experience then maybe they will stick with it and end up finding a job in an ROHS compliant environment where lead-free soldering skills will matter.

Lead free solder is a great way to mitigate envirnomental hazards for large-scale industrial operations. Leaded solder is a great way to introduce people to soldering in small scale educational operations. Comparing the differences between them is a great way to introduce people to some interesting aspects of metallurgy.

But mostly I'd like to point out that if you have come to the conclusion that "CD is a whinefest of people who can't pull together the right skills" then we have obviously been reading different threads. My experience on CD has been one of meeting lots of people keen to learn, and in turn learning from many very skilled people who take the time to post thoughtful, constructive insights.

Jason

P.S. If anyone would like more information on soldering iron tips, and extending their life using both leaded and unleaded solder, I have found the following document to be an excellent reference. http://www.newark.com/pdfs/techartic...ingTipLife.pdf

Re: Off season skills: Learn how to Solder
 

Actually I went into a rant of how solder used to work before the spiffy digital controlled tips. I'm going to guess that only a few people (Al, Ether) nodded and went "I've done that".

All the roboteers learned to use un-leaded solder on Saturday. It was a little more of a struggle, but they got it to work. We spent lots of time on keeping the tips clean, keeping the iron hot, keeping it well tinned at all times, etc. I still use leaded solder, but then I have the better part of a case of 1/2lb spools to go through. I bought and used ROHS compliant solder since they will see un-leaded solder in the future.

You missed the :rolleyes: in that comment. You've been here a long time, think of topics like Omni vs 6 wheel drive, Who in their right mind would use swerve, Mentors that build, Why Team [insert any world champ winner] should be [praised, hated, loved, followed, has too much money, too many people, karma, unlimited source of Andy/Mark parts or for that matter actually has Andy on their team]. Dozens upon Dozens's of posts, only a few that really add a great deal of value.

Like your post with the PDF on care and feeding of irons. That was good stuff.

Re: Off season skills: Learn how to Solder
 

A poorly made electrical connection will have high resistance. If current is forced through the connection, the power loss (P = I * I * R) can cause the all sorts of issues. In addition to causing electrical problems, the metal at the joint oxidizes much more rapidly than the intended design life, making matters worse. Sometimes, the oxidation proceeds rapidly enough that it is called fire. It does not matter whether the connection is soldered, crimped or bolted, it needs to be done correctly to get the desired result.


Using the various lead-free solders effectively is tricky. Only some of the technicians where I work are formally "Qualified" to do work with lead-free solder and we stick to one type. The document Jason linked to is the best and most comprehensive summary of best practices relating to the care of soldering iron tips that I have seen. Please remember that soldering iron tips are a semi-consumable item like your car tires. They will not last forever but will last longer if not abused.


Great advice. The lead-free stuff is probably not very good for you either. I always wash my hands well after handling any sort of solder. Often my hands are sticky from the flux anyways.