The process of soldering differs from welding in that it connects two pieces of metal together by melting a third piece of metal, one with a lower melting point. Welding, on the other hand, actually requires melting the metal that is being connected together. While additional metal might be added to the weld joint, it is of the same type that is being connected together.
Soldering can actually be used for a variety of purposes, such as "sweating" copper plumbing pipe together and making jewelry. However, when we’re talking about using a soldering iron, we aren't talking about those types of soldering. To solder plumbing pipe or jewelry, a torch is used. Although large soldering irons were used in the past by a tinsmith, in our modern era, the only thing a soldering iron is used for is making electrical connections.
The main reason why a soldering iron is used for electrical soldering rather than a torch is to localize the heat, controlling it so that it can't damage the components. While you could probably solder wires together with a torch, if you were to try and solder a printed circuit card with one, you would destroy it.
As electronic technology has improved over the years, there has been a need to improve the quality of soldering irons used for working on its components. The copper traces on modern circuit boards are much smaller than those found on electrical equipment manufactured 30 years ago. This means that the soldering irons must have better temperature control, as well as a smaller tip. A large tip or too hot a soldering iron could burn the board, detaching the copper traces.
Professional soldering irons used in industry are fairly expensive devices, often costing several hundred dollars. The main advantage of these tool is that they provide very accurate and adjustable temperature control. This allows the user to set the ideal temperature for the work they’re doing and be assured it will maintain that temperature within a very small tolerance.
For consumers, these soldering irons are a bit too much. I have one, which I've had for over 25 years, and it works remarkably well. But most of the soldering I do doesn't require that good a soldering iron, even when I'm repairing electronic equipment.
On the other end of the spectrum, there are inexpensive pencil type soldering irons with no temperature control whatsoever. The only control there is comes from the rating of the heating element. A higher wattage heating element will put out more heat than a lower wattage one. These inexpensive soldering irons aren't good enough for working on printed circuit boards but if all you are going to do is to solder wires together, they’re adequate for the task.
When selecting a soldering iron, you must select one appropriate to the purpose for which you’re going to use it. Always buy one adequate for your most critical task because that way it will work for less critical tasks as well. In this list, we are going to concentrate on soldering irons suitable for work on printed circuit boards, as selecting one for this application is harder than selecting an inexpensive one for simply soldering wires together.
There are three basic power sources for soldering irons; plugging them into the wall, batteries, or butane. While plugging in a soldering iron is less convenient, these soldering irons are the best for working on sensitive electronics, as they are the ones which provide ideal temperature control. Battery operated soldering irons don't work well as they go through batteries quickly and as the battery is used, the iron temperature drops. Butane models are good for emergency repairs in places where there is no electrical power, but one must be careful about damaging electronics with them.
Weller makes the broadest line of soldering irons on the market. This unit, while an industrial model, is an excellent choice for those that need a reliable, temperature controlled iron at a reasonable cost. Read Full Review
Weller is probably the biggest manufacturer of soldering guns, with the most models available. The temperature controlled iron I mentioned above is a Weller unit. Their equipment is top quality and while designed with industrial use in mind, their consumer line of equipment shows the quality their industrial line is known for.
This ESD safe soldering iron is part of their industrial line, but a lot of them are sold as consumer products. The controller and stand are separate to make it easier to locate on your workbench and you can use this iron all day long, as it’s designed for constant use. Temperature can be set anywhere from 350 degrees to 850 degrees Fahrenheit and held to plus or minus ten degrees. The innovative heater and sensor combination allow for quick heat-up and rapid temperature recovery while the station automatically powers down after 90 minutes of inactivity for safety and to help extend the life of the tip. Tips are replaceable, as well as the entire pencil, which is connected to the controller via a plug for easy changeovers.
This kit from X-Tronic wins the prize for providing the most for your money. A complete, temperature controlled soldering station, it even comes with a lighted magnifier to better see your work. Read Full Review
Hakko is one of Weller's biggest competitors. This soldering station is intended to be a high quality consumer product, providing an adjustable temperature range of 120 to 899 degrees Fahrenheit, with an accuracy at idle of 1.8 degrees. The digital display will read out in either Celsius or Fahrenheit, as you select with five preset temperatures which can be stored in the unit to facilitate ease of changing projects.
A ceramic heating element provides fast heat-up and thermal recovery as well as a wide selection of tips available for this unit and the stand has dual tip cleaners installed. This unit is ESD safe and will also work with Hakkko's FX-8804 hot tweezers for soldering of surface mount devices (SMD).
The digital display on this unit from Hakko provides instant and accurate readout of the set temperature. Five presets allow you to pre-program the unit for various common tasks. Read Full Review
X-Tronic is another strong competitor for Weller, producing a number of different soldering iron models, including this one, which is right on the edge between being an industrial or consumer unit. It has a temperature range of 392 to 896 degrees Fahrenheit, with 3.6 degree stability at idle. The digital display will provide temperature readout in either Celsius or Fahrenheit.
This kit comes with a lot of extras, giving tremendous value for the money and include a lighted magnifier for working, ten assorted soldering tips for a variety of applications and anti-static non-magnetic tweezers. It appears that X-Tronic is trying to make up for their lack of fame by providing a more complete soldering kit than the competition.
For those that don't want to spend the money for a temperature controlled soldering station, Weller offers this consumer model. While it doesn't allow you to pick an exact temperature and set it, it’s still adjustable, allowing you to use it for a wide variety of soldering tasks. Read Full Review
For those that want a good soldering station for electronic repair, without paying the price of the units we've seen, I'd recommend Weller's WLC100. This 40 watt station has an adjustable temperature control, although it doesn't have the temperature control circuitry of the more expensive units. Temperature control is managed by setting the wattage of power supplied to the iron, not a temperature setting.
The soldering pencil plugs into the base via a standard two-prong AC plug while an additional three-prong outlet is provided for connecting other equipment. While the temperature control is not as accurate as industrial units, the 150 to 900 degree ranges makes it useable for almost all electronic applications. Putting Weller quality together with this unit's pricing makes it a winner.
This butane unit from Power Probe is ideal for field service or use in remote areas where electrical power may be lacking. The kit comes complete with several tips and solder, all packaged in a convenient carry case. Read Full Review
There are only a few butane soldering irons on the market, of which Weller's unit and this one from Power Probe are the best. Intended for use in the field, where no electricity is available, this unit will work either as a torch or a soldering iron. As a torch, it reaches 2500 degrees Fahrenheit and as a soldering iron it will reach 950 degrees. Temperature control is imprecise and provided by controlling the flame level. It will operate as long as two hours on a butane charge at lower temperatures. This soldering iron is packaged in a plastic carry case, with everything you need, including solder and several tips.