Soldering Hell


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!



  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.

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.

Flux, Flux Flux.

I love these Flux Pens. See if you can get one or something similar:

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.


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.

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

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:

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.


I would disagree with

  1. Always keep your sponge wet

I never use a wet sponge. I prefer this kind of stuff.

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 :wink:

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!

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.

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.

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.

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. (Bot Thoughts: Dirt Cheap Soldering Iron)

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.

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.

Interesting, I keep hearing about flux and flux pens, but I've never seen any problems
with solder not flowing flow or not adhering, except in a few minor situations, like pins
with oxidation on them [like TO-220 parts seem to have], or the occasional crappy socket
pins. I use rosin-core solder, and 99% of the time it just flows right onto the joints, no
problem. I don't do much smt.

What are you guys doing that needs a flux pen? Could you qualify this? Specific situations
or for every solder joint of every kind?

Flux, Flux, Flux... Get rid of the lead free solder, use a good quality solder, Ersin, If they are still around Kester if not. I use leaded solder, a Hakko 936 iron and the brass tip cleaner. I have used water for all my life and I am finally free of the whole water mess.
I use the 'paste' flux from Radio shack for smd parts only. The paste is a petroleum jelly with Rosin in it.
Extremely messy but worth the effort.
FWIW, I learned to solder when i was 13 years old and passed the mil spec soldering requirements test at Gonset... I was the youngest to ever do that at Gonset. Gonset was a mfr of military RF devices, radios... Etc in the 40's and thru the 60's where I lost contact with them.
Soldering is an art, more than a science as with practice after a while you just know when to apply solder and when to lift the iron from the work piece.
Yes that tin crap does require more flux and No your work with lead solder isn't going to hurt anything ecologically either so use the lead solder and be done with it.
My $0.02 worth...


If all else fails, go for 300W [just kidding],


One thing that shows your soldering iron tip is too hot .... many years ago I had a
cheapo Radio Shack soldering iron, non-temperature-controlled. After having the iron
turned on for a couple of hours, the tip was already starting to pit and deteriorate.
OTOH, I have been using a temperature-controlled iron for the past 7-8 years, and
the original tip still looks like new.


[quote author=Dave Twilley link=topic=141820.msg1064682#msg1064682 date=1357761555]
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.

Lead-free is perfectly usable - but the iron must be a bit hotter than for lead/tin - otherwise you've just back to the cold-iron issues.

I've used lead/tin solder for 20 years, and for the last 10 have used tin/silver and there is very little difference at all if
the iron is hot enough. lead-free doesn't behave as well if reworking a joint, but you just have to add a little more.
With the iron at a higher temperature you have to switch off when not using to stop iron-oxide building up on the tip
(this prevents wetting of the tip).

One little detail (sort of mentioned above) is that the iron must melt the solder directly onto the part - place the end of the solder wire
between the iron and the part-to-be-soldered and squeeze it gently - once the solder melts (should take 1/2 second or less) it will
spread heat to the part to be soldered - you hold the iron there for 1 to 2 seconds to bring the part upto temperature, feeding in a
little more solder to fully wet the part, then withdraw iron and solder. Yes you do need three hands!

If it takes longer than 2 or 3 seconds then something is wrong (large areas of copper like ground planes take longer though, 5 to 6 secs).

Always wet the iron tip with solder, then wipe it on the wet sponge immediately before each joint. Any oxide build-up will
cause problems. Parts must be clean and bright too.

Temperature-controlled soldering iron is pretty much a requirement. Something like 300 C for lead/tin, 330 C for lead-free.

[PS lead contaminates your fingers and cannot be removed to any significant degree by normal soap - avoid lead solder!]

@oric_dan(333) - I use two types of solder, Radio Shack 0.015" silver bearing (95% sure it's not rosin core) and a 0.032" rosin core. The latter I use for big through hole stuff, pin headers.

It flows good enough without any help from a flux pen. But only just good enough. (I'm not saying its the best rosin core solder).

However, whenever I need to rework a joint, the flux pen has to come out. Also, with the pen, solder wicks into plated through holes better, so most of the time I just use the flux pen.

I use the thin solder for SMT and flux pen is a must there. The solder just flows so much better with it.

As for leaded solder, do your own research. LIke anything. There are multiple viewpoints on washing and how dangerous it is and such.