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[on:]

Hi,

After years of soldering (badly), I need some help to find out what I'm doing wrong.

Essentially my problem is that the parts I am soldering often start to melt or get very hot before my solder gets hot enough to flow on to the parts.  I've had this with all sorts of jobs and the only way I have found around it is to put a small blob of solder on my tip first to bridge the part to the iron and that seems to allow me to feed the solder into the molten bit.

In all of the videos I've seen, the idea seems to be to bridge both parts with the iron then feed solder in but when I do this the iron is on the parts so long that they start to melt while I am trying to feed the solder in as the solder just bends up rather than melt as its fed in.

I'm wondering if the solder I have is the problem, I have heard some people saying that newer lead free solder can be extremely difficult to work with.

Having worked mainly on connectors for my RC hobby I've always been able to throw bits away or cut wires back for another attempt but having just tried to solder some wires to a small ultrasonic sensor, I can see that i'll soon be destroying valuable components if I don't sort myself out.

In all the videos, getting solder to flow seems to be the easy bit!

Thanks

Dave

[Reply #1 on:]

1) Always keep your sponge wet
2) Always keep your tip clean
3) Don't use the absolute point of the tip, it's not the hottest part. Use the side.
4) Make sure you have a good enough iron that is getting sufficiently hot. Too cold and you'll struggle, especially with lead free solder.
5) Use additional flux, if required, to help the solder flow. Of course, you need the iron tip to be hot enough for the solder to melt properly.

I'm sure there will be some more experienced solderers that can offer other advice.

[Reply #2 on:]

If you don't mind lead use 60/40 medium diameter.
A HOT iron is essential!  40/50Watt get in and out quickly.
Keep the point clean on a wet sponge.

[Reply #3 on:]

Flux, Flux Flux.

I love these Flux Pens.  See if you can get one or something similar:
http://www.mgchemicals.com/products/prototyping-and-circuit-repair/pens/rosin-flux-835-p/

[Reply #4 on:]

There is one thing I've always found the and that is to apply the solder at the 'junction' of tip and work a slight delay after applying heat...
The 'slight delay' is the art of soldering.

Bob

[Reply #5 on:]

I'm wondering if the solder I have is the problem, I have heard some people saying that newer lead free solder can be extremely difficult to work with.

Yep. Lead-free is very troublesome, I imagine that's the problem.

At a hobby level you're not going to save the planet by using lead-free. You might as well use lead.

[Reply #6 on:]

I would definitely recommend using extra flux. Ever since I started using flux I've never had a problem with wetting.

[Reply #7 on:]

Thanks all for the quick replies.

I have a temperature controlled iron from Maplin (which I run at 350c, it'll go to 450c though) and I broke out some new tips this evening just for the sensor, I've got 1.2mm lead free solder.

This is the iron I use: http://www.maplin.co.uk/48w-lcd-display-solder-station-98133

I have a flux pen but if I'm honest I don't know how and when it should be used.

My solder station came with a sponge which I use all the time to keep things clean.

I'll get some leaded solder and see how that goes as a starting point.

Dave

[Reply #8 on:]

I would disagree with

1) Always keep your sponge wet

I never use a wet sponge. I prefer this http://dx.com/p/soldering-iron-tip-cleaner-ball-golden-137118 kind of stuff.

[Reply #9 on:]

At work, I use a 120W iron normally set to 320C, and leaded 60/40 solder. Gets up to temperature and transfers heat to the workpiece quickly, and with the occasional tip-change the same iron works for everything from soldering shielding tape over everything, doing wiring looms, connectors and sticking stuff on PCBs. I'm hardly an expert (although I rarely fuck anything up so badly it can't be re-done), but the golden rules for me are:

1) Plenty of flux
2) Clean EVERYTHING with plenty of IPA before working on it
3) Keep that tip tinned and shiny
4) Use the brass brillo pad things instead of a wet sponge

Lead-free solder is horrible, nobody I work with likes it, and thankfully we're not required to use it due to an exemption. I'd NEVER use the stuff at home either. Just wash your hands after handling it and there's no real harm... although good luck finding it at Maplin these days!

[Reply #10 on:]

I have a flux pen but if I'm honest I don't know how and when it should be used.

If your putting solder to something, use flux.  If I turn my iron on, I am opening my flux.  I don't use a pen, so I have a small painters brush that I apply flux with.  And I put it on everything and lots of it.

I use leaded 60/40 at .032" solder.  I love it.  My iron sits at 300C most of the time.

I also use a wet sponge.  Works for me.  Every so often, I clean the tip and go back soldering.

[Reply #11 on:]

I use lead-free solder, well, because I sell my stuff internationally... so I'd rather keep it lead-free. At first I hated it, but now it's no big deal to me. In fact, they're cleaner looking than using a 60/40 lead. (though not as shiny).

Keeping a CLEAN tip is a must... gunk on your soldering iron tip prevents efficient transfer of heat... which ruins soldering job.
I use this to keep my tips clean.


Keeping the PCB surface clean and oil free helps too (use a 91% Isopropyl alcohol). 

Flux helps too for "stubborn parts". I use a dropper bottle with a syringe tip.

[Reply #12 on:]

the iron is on the parts so long that they start to melt

What I don't understand is what exactly is melting here? About the only thing I've seen
that will actually melt is the plastic case of an Led.

I've not used lead-free solder, but here's my 2-cents into the pot.

1. use a damp sponge, and not a wet sponge. Squeeze out the excess water.
2. wipe the tip on the sponge after every few solder joints.
3. use a beveled tip and not a pointy tip, as the former has a nice flat surface and
    will apply heat much better.
4. I don't know about heat levels, but my temperature-controlled station has a mark on
    the dial that works great for standard 60/40 flux solder. Then I sometimes have to
    adjust  +/- from there for very small parts or larger parts, pcb-heatsinks, etc.
5. I never use extra flux, as the solder has rosin flux in the core already.
6. some parts, typically TO-220s, have an oxidation on the leads, and I usually scrape
    this off with an exacto knife before soldernig.

7. be sure to tin the new solder tip, and also dab some solder on the tip after it's
    warmed up at the beginning.
8. apply the tip to one side of the joint for a second or 2, and then touch the solder
    to the other side of the joint so it flows across via surface tension. If the heat is
    adjusted correctly, it won't take any longer than this.
9. it also helps to again dab a bit of solder on the tip before making a joint, after
    the tip has been wiped clean.
10. for some reason, sometimes the pins on some DIP sockets don't take solder well, so
     if I happen to have received such sockets, I toss them in the garbage right off.

[Reply #13 on:]

A flux pen will change everything.

I like the Kester 2331-ZX. You could use radio shack flux paste, but honestly the pen works much better with less mess. I've tried the no clean Kester but I don't like it as well. Anyway your jaw will drop the first time you see solder flow after application of flux.

I proved to myself that it's possible to solder with a $ Store cheapo crap soldering iron provided I used a flux pen. (http://www.bot-thoughts.com/2012/10/dirt-cheap-soldering-iron.html)

The next great thing is a brass sponge tip cleaner.

Works so much better than water sponge, with so much less mess and no need to pour on new water.

[Reply #14 on:]

Anyway your jaw will drop the first time you see solder flow after application of flux.

Agreed.  The other jaw-dropping moment for me was when I applied the flux pen directly to solder braid.  The rate at which solder was wicked-up was almost like magic.