Choosing the Right Soldering Iron for Electronics Work

Dan, one of my Facebook buddies, wrote to me asking about choosing a soldering iron:

Soldering Iron Gun

"Quick question... I'm looking for a new soldering iron. would you recommend anything under 40 dollars without a soldering station? I'm getting tired of my RadioShack 45 watt iron with the screw on tips (and having to use a bench grinder everyday to clean the tips)."

Soldering Iron Gun

I've been asked this question quite a bit, so I thought it was time to put something together explaining about soldering irons, flux and tinning.

Soldering Iron
The first thing I would recommend is getting an adjustable temperature soldering iron, and get used to setting the correct temperature for the different types of parts you are working with - hotter for larger gauge, and cooler for thinner, finer work. I typically work in the 325F to 400F range. I've been using the Velleman LAB1U, it has a built in multi-meter and power supply. These can be a bit pricey, so check out the Weller brand - sometimes they go on sale for around . I would avoid the Cold Heat soldering irons - they are unsuitable for delicate electronics, as are the big soldering "gun" type irons.

I used to use quite large gauge solder and tips, but just recently (after doing a lot of surface-mount work) switched to 1/32″ tip and 0.32″ diameter solder. This allows for much finer control with less overspill.

My soldering iron has a built in "damp sponge" to clean off excess solder inbetween uses. In the past I have used regular paper towels to do the same job, but a dedicated sponge with a circular hole cut in the middle really works best.

Helping Hands
The next thing I wouldn't be without is are some "Helping Hands" - these are pairs of crocodile clips that can be used to hold the workpiece while you concentrate on the soldering. this is really important, as it won't be long before you realise that you need 4 hands to solder things.

Even better than helping hands is a:

Bench Vice/Vise
I bought one of these 2 years ago and it's proven to be invaluable. The brand I use is "PanaVise" and they come with a range of bases and options - Fry's carries them, and they are available online. You can put the whole PCB you are working on into the vice, insert the components and then just flip it over to solder.

Flux Pen
Rosin Flux is a substance that encourages the solder to flow. If you find that you are having trouble getting a good solder joint then it's probably because the heat transfer isn't working correctly, or the components are dirty. Applying some solder flux to the joint area will really help - I've been using a flux pen for years and wouldn't want to be without one. An alternative is flux paste - like toothpaste it comes in a tube and can be applied with the fingers.

Tip Tinner and Cleaner
When you first fit a new soldering iron tip it will be bright, shiny and very difficult to work with. The solder will not stick to it and so you cannot "tin" the tip properly. Some people will use fine sandpaper to break in a new tip but I prefer to dip the new tip into some RadioShack "Tip Tinner and Cleaner". This starts the process nicely. It's also a good idea to dip the soldering iron after you are finished, and before you switch off. I find that it really helps to prevent the tip from wearing out prematurely.

Fume extractor
If you do a lot of soldering, then you need to get something installed on your bench to divert the fumes away from your face. It's not recommended to breath in solder fumes at all. I use a small fan, but a proper extractor is a very good idea.

Wire Cutters
The final piece of essential equipment is a pair of sharp, flat bottomed wire cutters. These are used to trim off excess component wire (the "leg") after soldering. The flat bottom is important to get the cut as close to the PCB as possible. Don't go too cheap with these, I paid about for mine.

That just about covers the basics of soldering, I would also think about getting a loupe (magnifier), some solder wick and solder "sucker" for removal, wire strippers and isopropyl alcohol and an old toothbrush for flux removal.

Very soon I'll put together a series of articles on soldering technique - covering basic through-hole assembly, and the more advanced surface-mount technology.

Choosing the Right Soldering Iron for Electronics Work
Soldering Iron Gun