Soldering questions

[Nathan]

Hi, I'm a programmer trying to solder. Dangerous combination, I know.

I've got two questions...

One: I bought a cheap soldering iron from RadioShack, and frankly is sucks. What's a good soldering iron to buy on a budget?

Two: This may sound a little odd, but I'm trying to solder the ends of a piece of 1.x mm thick copper wire together. Do I need to get the copper wire hot enough to melt the solder directly, or can I just get some solder on the tip of the iron and then put that on the wire?

Thanks,
Nathan

[John Gutmann]

The soldering iron from radio shack doesn't suck you just need to learn how to use it. I have been using the cheapest one radio shack sells for about 2 years now.

Try Googleing soldering tutorial first. There is a good video on makezine.com

-John

[Kevin Sevcik]

One: I'd really recommend just getting a Weller iron or some similar brand name. Most others are just going to disappoint you.

Two: If you mean you're trying to make a butt join, like if you stuck two pencils together eraser to eraser, that's a bad idea. It's better to twist the wire together and get a reasonable mechanical connection first, then apply solder. As far as the actual application, you need to do three things. First, clean the wires (twisted together) and your iron tip. Next, tin the tip with a small amount of solder. The idea is to have a little solder there to increase the contact area with the wire. Finally, you have to heat up the wire with the iron and apply solder to the wire or right where the iron touches the wire. The important thing is to make sure solder "wets" the copper. It should look smooth and flat like a drop of soapy water spreading out on a piece of glass. It should not look like a bead of water that's bunched up on a piece of plexi. If it looks like the latter, you didn't heat up the copper enough before apply solder and you've gotten a cold solder joint that's likely to result in disappointment sometime in the future.

[ebarker]

Somewhere on the web there should be a good tutorial but I'll give you the basic rundown.

Let's start with basic defects.

a) using solder to make 'mechanical' connections
b) dirty or corroded copper
c) using the iron to melt the solder, not the work.

The answers.

a) If a connection has any sort of mechanical stress it is to be configured to handle the stress without solder. The solder just takes care of the electrical part. This is true of cable, harnesses, are larger leaded parts. Surface mounts parts have low enough mass that the soldered joint is sufficient.

b) if the materials are excessively corroded then clean the work with an abrasive material. Use solder designated for electronic work. DO NOT use solder for plumbing. plumbing solder has highly acidic cleaning fluxes and will destroy electronics. Electronic type solders has fluxes (cleaning agents) that are suited for this type work. In hobby work if you use a resin core flux solder it will smell like turpentine pine. You can leave the residue on. The new organic core fluxes wash off in water or with a damp cloth. If you leave the flux residue on it will eventually corrode and get messy.

c) what heats what ? This is where a lot of people really get messed up. The iron heats the work, the work melts the solder. Go get a perfboard with a lot of tin plated holes and a bag of cheap resistors and practice. Put the iron tip into the vee between the resistor wire and the pad. put the solder on the opposite vee and it will 'strike' and the flux will clean and the solder flow.

You don't ever want to solder butt to butt to wires. you can do it but it will be a piece of complete junk.

[N7UJJ]

Nathen,

You are right, the soldering iron should heat the metal hot enough to melt the solder. Putting meleted solder on cooler wire can produce a weak :cold solder joint"

Soldering irons and soldering funs have a wattage rating. The small the wire (or metal) a lower wattage iron is appropriate. Thicker wire may need a larger iron. Really big stuff may even need a tourch.

So your Radio Shak iron is probably not able to heat the wire enough. You will have to use a higher wattage iron or solderng gun.

Just like hammers: there are small ones and big ones; it just depends on how big the nail is.

BTW: if you can solder, you can fix half the electronics repairs you will ever have in your lifetime!

Good luck,

Allan

[Nathan]

Unfortunately it is a "butt-to-butt" connection, I think. What I'm trying to do will look like this:

The two ends of the copper wire will meet at approximately 45 degree angles. This is going to be an antenna, so there's virtually going to be no stress on the wire itself.

There does need be be an electrical connection between the two ends, which I think someone said the solder will provide. But again, do I really have to heat up the wire enough to melt solder directly? I bought the 40W iron from RadioShack and after holding it on the wire for like 10 minutes it still wouldn't get hot enough to melt the solder!

Thanks,
Nathan

[Gdeaver]

But splicing with solder is a bad idea. If you must but splice, then you need to look at brazing not soldering. For small wires, jewelers use silver brazing wire and flux. For larger wire normal brazing rods will work. Brazing is done with a torch not an iron.

[MrForbes]

for heavy wire like that you might want to use a soldering gun. Small soldering irons work great for electronics work (circuit boards) but not for heavy stuff like that.

You do need to have the parts hot enough that the work melts the solder, otherwise it will not bond. And for the job you're working on, a blob of solder holding the ends of the wires will probably work ok. however, if you could rearrange the shape of the wire so the wire ends have some overlap at the solder joint, it will be easier to build and stronger.

[John Gutmann]

For trying to connect 2 wires together that have the purpose of conduction I agree that it is a bad idea. But I have done many many projects such as this and never ahd any problems with a bit joint. Just solder it on a flat metal surface so that the solder doesn't fall off.

Have you tried heating the metal a little with a propane torch?

-John

[EricVanWyk]

Big copper wire is a pain to solder, as it is essentially a giant heat sink. The secret is to get the entire thing hot. I'd recommend baking it in the toaster or microwave until it gets good and crispy, and then quickly use the iron to get it the rest of the way there.

As fair warning, you are not using the right tool for the job. I use a 500 Watt Iron for things easier than this.

I would try wrapping the joint with some bare wire to give your solder something to stick to. Might give it a slightly better chance.

Good luck, you'll need it, especially if you think I was serious about the microwave

[Kevin Sevcik]

Originally Posted by EricVanWyk

Big copper wire is a pain to solder, as it is essentially a giant heat sink. The secret is to get the entire thing hot. I'd recommend baking it in the toaster or microwave until it gets good and crispy, and then quickly use the iron to get it the rest of the way there.

As fair warning, you are not using the right tool for the job. I use a 500 Watt Iron for things easier than this.

I would try wrapping the joint with some bare wire to give your solder something to stick to. Might give it a slightly better chance.

Good luck, you'll need it.

Eric.... I'm going to pretend I didn't hear you suggest that this impressionable student ruin his parents' microwave by nuking a single piece of copper wire until hot. There's a reason they say not to do these things and trying to microwave a metal object long enough to significantly preheat it will likely greatly shorten the life of your magnetron.

[dtengineering]

Originally Posted by Nathan

Unfortunately it is a "butt-to-butt" connection, I think. What I'm trying to do will look like this....

That looks like it should work fine... thank you for posting the photo, as it makes it much easier to understand.

Heat is an issue and there is some good advice given here. I like to use a little butane torch for heating stuff like this. You can get fancy ones at cooking shops for doing creme brule, but you can also get cheap (sub ten bucks) ones at discount hardware and surplus stores. Princess Auto comes to mind, but they haven't expanded to the States yet, so I can't recommend a local shop to you.

The high wattage soldering gun should work, too as will the propane and even heating it up in the oven (or bbq) and then using the soldering iron, I suspect. You just need some more heat! (And that whole "clean surface" thing... thats kind of key, too.)

Jason

P.S. If you do decide to heat it up in the microwave, please make sure you take the time to take photos and post them here.

[eugenebrooks]

Go buy yourself a Hakko 456 soldering iron.
It was designed for situations like the one you show.

A good general purpose soldering iron is the Hakko Mach-1,
that heats up to soldering temp from stone cold in 10 seconds.
It is small enough to do fine pc board work, and you can
change to a larger tip that can handle heavy wire. I rarely
have to resort to the 456 these days. The mach-1 is a really
good iron for use in the pit because of its fast heating time and
the fact that you can get a heat proof sock for it. After soldering
you put the sock on it and no one gets their fingers burned
with a hot iron that has been laid down.

Leave the bbq for heating aluminum heads in preparation
for driving out valve guides...

Eugene

[Al Skierkiewicz]

Nathan,
What you are trying to do is one of the most difficult soldering jobs there is. From the picture, I will assume you are trying to solder to a connector of some sort. This will prove to be bad for the connector is not done correctly. The first thing you have to realize is that an iron no matter how hot, must conduct the heat to the work. If the tip is dirty or corroded, no heat will transfer. Start by touching the tip with some solder to form a pool of conducting solder to transfer the heat. If you need it, a wet sponge can be used to clean the gunk off the tip.
Second, the wire must be clean to accept the solder once heated, Sandpaper works OK for this, be sure the wire is nice and shiny. Then tin the parts separately by heating and applying solder to the metal. Note in your picture how there is solder on the wire almost 1/4" from the end? That came from the tinning process. Do the same for the connector leaving enough solder to form a blob on each of the intended targets on the connector and wire end. When the wire is hot enough to melt solder then bring all three things into contact, the iron, the connector and the wire. When you see the solder start to flow, remove the iron and hold the wire in place while blowing on it to cool it down. You might want to try soldering scrap wires together before tackling the connector. There is no coming back from a damaged connector at the frequency this antenna is designed for. A good connection will have a shiny appearance on the solder surface. If it looks textured or crystalized, it is cold soldered and needs to be redone. As others have pointed out, this type of connection is only as sound as the solder so don't expect it to hold together with movement. Let us know how it goes.
BTW, if you hold the wire with a pair of pliers near the point you are trying to solder, or if you have the wire in a vise to hold it, the heat may be drawn away from the tip of the wire. Try holding the wire further away. I think when you add some solder to a clean iron tip will you will have much better results.
I forgot to address the suggestions about the microwave. Please don't do this! Damage to you and the microwave may result.

[ebarker]

Nathan,

I gotta ask the programmer what he is up to.

We've gone from software to soldering to E-Mag.

I see an antenna. Who/What we talking to ?

Inquiring minds need to know.