Soldering Tips: How To Solder Properly

Amped blogger Pat Freuler has written a handy guide on how to solder   16-May-13

Soldering Tips: How To Solder Properly
Image courtesy of Tim Patterson

Pat Freuler is a design engineer for Amplified Parts, he has noticed a surge in DIY guitar hobbyists asking for advice on soldering, so has tackled the subject head-on in this guide to soldering for guitarists...

One of the biggest obstacles facing new electronics hobbyists is the art of soldering. Based on the number of non-working kit builds and DIY amp/pedal modifications I've been asked to repair, as well as my own experience as a novice builder, poor soldering is the most common source of unsuccessful electronics projects.

And a lack of early success for a beginner often leads to abandoning a project or the entire prospect of kit building. I've cobbled together what I hope will be helpful tips on basic soldering skills essential to the successful completion of any electronics project. Like any new skill, practice is key.

Don't skimp on your soldering iron. Starting out it isn't necessary to get a top of the line soldering station, but a basic name brand soldering iron like Weller or ECG can be purchased for around $20, and will last for years. A soldering iron stand and a small damp sponge used to clean the iron will complete a basic soldering set up.

If electronics is something you anticipate staying with for a while, it would be worth the extra cash to pick up a basic soldering station with an adjustable heat range. Quality units are available in the $50 - $60 range.  An adjustable station will pay off in the long run. Never use a soldering gun for several reasons, but primarily because they get too hot and are big and clumsy.

When you get your new soldering iron, you'll need to tin the tip. This means heating the iron up and covering the tip with a coat of melted solder.  This seals the surface of the tip and provide better heat transfer, and better solder joints.

While in use, ideally you should wipe the tip clean on your damp sponge (provided with many stations and soldering iron stands) before  each use.  An alternative to the damp sponge tip cleaner is a brass wire sponge tip cleaner. The advantage of the wire sponge cleaner is that you don't drop the temperature of the soldering iron like you do when using a damp sponge.

It also cleans just as well if not better than a damp sponge and lasts a very long time. These are widely available with a holder for under $10. When you are finished soldering, tin the tip again before turning the soldering iron off.  Never use an abrasive such as sandpaper or a file to clean a tip. Modern tips are often a copper core plated with an alloy and once this outer coating is gone the tip is useless.

Use 60/40 tin/lead rosin core solder and avoid lead free solder. Lead free solder melts at a higher temperature and can be a difficult to work with as well as being much more expensive than tin/lead solder.  Lead free solder is becoming the standard in electronics manufacturing to comply the the RoHS directive, concerned with the leaching of lead and other metals into the environment.  As a hobbyist, stick with the leaded solder.

The most useful diameters of solder are .03" and .05". I use the .03" for solid state PCB (printed circuit board) work and .05 for tube amplifiers with larger lugs and terminal points. Don't use plumbing solder that is available from home improvement stores.

The basic rule of soldering is to heat the metal (wire and connecting point) and then apply the solder. If you melt the solder on the tip of the soldering iron and apply it to the connection, you'll likely end up with a cold solder joint. A good solder joint is smooth and shiny. A cold solder joint is dull and often lumpy or cracked.  It might look connected, but often becomes intermittent or open, resulting in frustration and excessive time troubleshooting the bad connection.

This is where the "art" of soldering comes in. With practice your goal is to find a balance between enough heat to create a good solder connection without overheating the parts you are soldering. This is especially true of semiconductors such as transistors, diodes and ICs.

They are prone to failure if exposed to overheating. Too much heat can also damage the copper pads and traces on a PCB (printed circuit board). And, when soldering the ends of insulated wires, too much heat can cause the insulation to melt and pull back.

An easy and inexpensive way to get some soldering practice is to use a prototyping board. These are available through many sources in PCB and lug/turret style. Many electronics suppliers sell grab bags of miscellaneous resistors, capacitors, transistors, etc., for pennies on the dollar.  You can use these to hone your soldering skills.

These tips are the basics of soldering and there is much I've left out. As you gain experience and move on to more advanced projects, you will pick up techniques and learn about soldering tools and supplies that will make the job of soldering easier.

I'll close with a brief comment on safety.  Like anything involving potential injury, common sense goes a long way. Soldering irons can run as hot as 900°F. I've burned my fingers using a soldering iron and it was always the result of a cluttered workspace, being distracted or going the extra hour instead of taking a break. Keep your work area well lit and clear of all but the essentials. While soldering, wear eye protection and long pants. If you drop the iron, let it fall.

Sounds simple but most of us instinctively to try and catch something we drop. Breathing in solder fumes isn't good for you. There are fume extractors which are basically a small fan pulling the fumes away from your area and pushing them through a carbon filter.  At the very least, work in a well ventilated area or have a small fan blowing the fumes away from your work area. If you solder regularly you might consider getting a solder fume extractor.

That's it for now. There is a wealth of useful information on the topic of soldering and I've only touched the surface of the topic. But, as I stated at the beginning, experience is the best teacher, so break out your soldering iron and jump in.

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