Basic soldering tips

Thread Starter

Then along came a dummy

Joined Jun 24, 2005
Hi guys,

I'm still new at this and am practicing soldering. I'm just soldering with small capacitors and resistors now. Just practicing really. When i solder i touch the tip to the wire and hold the rosin core at a 45 degrees angle on the other side of the wire.

I make sure that the core does not come into contact with the heated solder tip. But when the rosin melts it inevitable sticks to the heated tip and not the wire lead to which intend. Furthermore if it doesn't stick then it leaves a big bulbous joint. This must be a cold solder joint from the pictures i viewed.

Maybe i'm just venting here, but anyone have any personal tips on hwat they do or what i might be doing wrong?

Thanks a bunch.


Joined Apr 20, 2004

Always wipe your soldering iron tip clean on something like a damp sponge or several thicknesses of damp paper towel. Touch a bit of solder to the iron so it is wet with solder - that way it will transfer heat more readily.

If the wire is hot, solder will flow onto it easily. If you're soldering to a pad on a pcb, hold the tip in contact with the pad and lead. You want the rosin to get on everything - it cleans off oxide that might prevent the solder from wetting the metal.

Wierdly enough, too much heat will make poor solder joints. It burns off the flux and leaves the solder looking dull and jagged. We call this a cold solder joint. You get better results with small solder - I use .031 diameter. I'm still using tin/lead stuff. The new solder that's all tin with a bit of silver needs too much heat for my taste.


Joined May 16, 2005
In soldering, cleanliness is critical. Just prior to soldering, clean your component leads. Clean your pads or lugs. Clean & tin your iron tip. Clean your solder too! Oxidation is not your friend. Beenthere's post describes good tip cleaning & tinning procedure. Isopropal alcohol and tissue paper works for cleaning everything but the iron. Try to find one of the "lint free" tissues.

You want the solder to be melted by the lead and the pad/lug - not by the iron. Solder will flow toward heat whenever gravity permits, so if it is heated by the iron it will simply build up on the iron.

I like to put the iron simultaneously against lead and pad/lug for a few seconds, then apply solder. Solder goes on the side opposite the iron. I remove the iron first, then remove solder feed.

Heat from iron should be approximately proportional to size of lead and pad/lug. Small stuff needs lower power. Big stuff needs more power.

A correct solder joint will have a concave fillet of solder, not a convex blob. Blobs can hide inclusions and bubbles. Blobs are bad. Good solder joints look dainty, like jewelry - not bulbous like cowpies.

Soldering is a manual skill, and as such it requires practice.


Joined Dec 14, 2004
Soldering 101

#1 Too hot will destroy traces, too cold will not flow well. You source does not need to be higher than 40 watts. Any higher you risk using too much heat and reducing the life span of your tips.

#2 Keep tips clean. I routinely use a razor blade and a little tin with a solder tip cleaner in it. You dip it your hot tip, it tins it and cleans it. You don;t have to razor blade it, but I like to keep all gunk off of it.

#3 Use a damp sponge. Not wet, not dry. BEFORE you place the tip to the trace, you wipe the tip QUICKLY to not lose to much heat and to give you a non oxidixed side on the tip. This is the side you will place against your trace or leg.

#4 Make sure you use the right type of flux. DO NOT use any form of plumbing flux paste. It has chloride ions typically in it and it is HIGHLY conductive. Instance short circuit using this crap. Stick will the liquid flux you can buy at a electonics store.

#5 Do not melt the solder to the tip then place the tip on the trace. Very bad. Heat the traces or legs of the components directly. If the component is heat sensitive like an IC or has plastic in it that could melt, place a heat sink between your point of heating and the point of issue. Alligator clips, forceps, needlenose pliers, what ever you can fit to disipate some of the heat. Let the sensitivity to heat determine how big of a heat sink you should use.

#6 Just a personal thing. Don't use rosen core solder. Its just plain nasty. Its fumes are disgustingly toxic and you can do a much better job with some nice thin solder and liquid flux.

Typically if you fluxed right and you placed the hot tip to the leg/pad/trace and got it hot enough so that the flux is boiling and the solder will melt, it will flow right into position for you. You shouldn't have to be fighting with it ever.

Anytime soldering something is hard or not working, there is a good chance your doing something wrong or you forgot something on the way. Flux, cleaning the tip, not hot enough, or too hot, etc. DONT EVER, EVER.. once more, EVER use those soldeirng iron that look like a screw gun you pull the trigger on. Those things generate heat at 100 Watts and and burn though a PCB fairly easily.
#7 Always turn iron off or onto lowest setting whilst not actually soldering. The lower temp will prolong the tip life by reducing the oxidisation of the tip metal. Pure metal is a better conductor than its oxide. Also, tips are really difficult to remove once they become corroded into the barrel. Often a new barrel or iron is required- 16 years of classroom experience tells me this!


Joined Aug 14, 2005
Re #1 & #6. The best soldering iron is one with high power AND temperature control. A 40W iron may sometimes be on the low side, at least when you solder more than 2 layer pcb's with power layers. 80W - 100W with a good & fast temperature control is a good alround soldering iron/ station. 50W with pencil thin tips for SMD works only.

When using a soldering iron, change and use correct sized tips for different pads and components. In this, there is no one-size-fits-all :D

TOK ;)


Joined Jun 23, 2004
one thing to remember, is that the copper (trace, pad, via, plane) is really only glued to the substrate, which is mean't to take some heat, but not for extended periods or too repeatedly. once you have the trace come away from the board, the real trouble begins - beware using glue to fix you can create some real toxic fumes this way -

not all bad joints can be spotted visually, I've had PCB connections that look bright & shiny with no excess, but have an oxide layer between pad copper and solder, so everything looks and feels sound but has resistance in the megohms. (this situation probably would have passed factory testing, but months or years later a small inclusion has become a self formed oxide layer)

beware the badly made PCB, large components and small pads generally dont mix (specifically large components like TO-220 packages & 40mil pad)
not so prevalent nowdays with everything doulble layer or more, and most PCB production houses specifiing minimum standards, but if you're starting into repair you may still see some single layer boards out there. I do.

some really great tools if you're into proto/hobby PCB manufacturing, or even repair...

my $0.02 +GST
Brandon made this comment.

#6 Just a personal thing. Don't use rosen core solder. Its just plain nasty. Its fumes are disgustingly toxic and you can do a much better job with some nice thin solder and liquid flux.

I don't know what kind of rosen core solder you are using but the stuf I use has the same thing in the core as liquid flux that you apply. It is a standard RMA flux that is based in pine resin (Yes from pine trees). The only toxicity of it is the smoke that comes of it whe you over heat it. These fumes are the same as if you over heat the liquid flux you speak of.

With reference to the wattage of a soldering iron. I am not quite sure how anyone could produce good joints with any iron over 40W. Also the wattage is not the bit you should be worrying about. The temperature is much more important. Standard 60/40 solder has a liquid point of approx 275C. You should have whatever iron you are using set to about 300C so when you place the iron on to the workpiece it will drop close to the 275C required.

I spent many years teaching military technicians to solder to the same standards as used at NASA. As one can imagine the quality requirments for NASA and also military aircraft is pretty high. The vibration of a jet engine can very quickly cause a dry/cold solder joint to fail. Also if you happen to have caused a bubble to form in the joint and the aircraft climbs to 40,000ft that bubble can explode and cause the joint to fail.

Obviously the run of the mill back yard solderer doesn't need to worry about these things but it is still nice to liook at well formed solder joints.


Joined Jul 2, 2006
well, if the solder sticks to my iron tip i usually clean it with few layers of a thick cloth, but when i forget it and it forms a solid deposit on the tip i just SAND it away with normal sand paper(this also gets rid of that oxide layer). I don't know whther it is an accpeted way cause i am also new to this soldering.