Temperature controlled soldering iron

A temperature controlled soldering iron is a hand tool that provides heat to melt solder. It consists of:

The heating of electrically powered soldering iron is accomplished by running an electric current through a highly resistive wire made of nickel and chromium.

This wire is wrapped inside the heating element. It has a very high melting point and does not oxidize easily. During the manufacturing of soldering iron, different wattages can be achieved by changing the number of turns of nickel-chromium wire that is wound around a central core.

The most popular in the USA

Weller WE1010 solder station

Hakko FX-888D soldering station

Weller WLC100 (cheap solder iron)

Most of the soldering irons come with interchangeable tips.

The tips are interchangeable to allow the use of the same soldering iron for soldering a broad range of component types.

A good soldering iron is the single biggest factor to proper soldering.

It is important to have a quality tool for successful soldering.

Different types of soldering projects require different temperatures, so being able to change the temperature on the iron tip is critical for successful soldering.

These days unregulated single-wattage soldering irons are becoming rarer - most of the standard soldering irons have some kind of temperature control.

Temperature controlled soldering iron allows you to solder a wider range of electronics and circuit boards without overheating and damaging them.

It has the capability of controlling and adjusting the temperature of the iron tip. That means that operator can set the desired temperature of the tip with knob or push-buttons located on the front panel of the base unit.

Temperature controlled soldering irons come with a built-in adjustable temperature setting. Electronic temperature control allows precise control of the heat level at the tip of the soldering iron. Most of the soldering irons produce tip's temperature in the range of 662-842 degrees Fahrenheit (350- 450 degrees Celsius).

Electronic temperature control means you'll always know if the tip of the soldering iron is hot enough for the material you are soldering.

It makes your soldering work a whole lot easier.

This means that you can rest assured that your soldering iron is hot enough and ready for soldering, and at the same time you know that it is not too hot to burn some temperature-sensitive components on the circuit board..

If you do not pay attention to the temperature of the iron’s tip you can accidentally damage or ruin your soldering project by applying too much heat. For every soldering task, you need enough heat to quickly and reliably melt the solder and apply it to soldering joints, but you do not want too much heat that can burn or melt delicate electronic components or circuit boards.

The first attempt at temperature controlled soldering iron was made in 1949 by American company American Beauty. It was a simple system that allowed some adjustment of the temperature of the soldering iron. Later, in 1960, temperature controlled soldering iron was patented by Weller company.

Many new models of temperature controlled soldering irons have been introduced on market in the USA in recent years. Various manufacturers offer new models of variable temperature soldering irons.

Even dough brands such as Aoyue, Lonove, X-Tronic, Vastar are not as famous as Weller, Hakko and Pace they offer a solid quality of the soldering tools at a lower price.

These days it is possible to buy a good temperature controlled soldering iron with a digital display for under $50.

Top-quality temperature controlled soldering irons are in the range of $100 -$140 (Hakko FX-888 is around $100 and Weller WE1010 is around $140) but you can buy them at a lower price when they go on sale.

Many soldering stations are capable to accurately maintain the temperature at desired level – for example on WESD51 Weller soldering iron you can precisely control the temperature of iron within +/- 9 degrees Fahrenheit.

Temperature controlled irons should be used whenever we have to solder temperature-sensitive components.

Three basic designs of soldering irons regarding temperature control.

The first type of soldering iron does not have any form of temperature regulation.

This is a simple unregulated soldering pencil - just plug it in the power outlet and in a couple of minutes it is ready for soldering. This soldering pencil is usually sold as a separate soldering tool but it can be a part of a soldering kit.

It is good only for do-it-yourself projects, soldering a wire and some standard soldering projects in households. This type of soldering irons is the simplest and the cheapest type of soldering irons.

The temperature at the tip of these soldering irons can vary significantly during use. This is a situation when the iron is not being used but still turned on or where it is being used consistently for prolong time..

The price for a simple soldering pencil in the USA is in the range of 15-30 dollars.

The second type of soldering irons is a temperature controlled soldering iron. These soldering irons are used for fine, precise work.

These soldering irons have built-in temperature control to ensure that the temperature of the iron bit is maintained at a fixed level. A thermocouple is built into the iron tip or shaft, which monitors temperature. Some soldering irons have a bimetallic strip thermostat built into the handle.

These soldering irons come with a low-voltage power station (typically around 24 Volts DC) and a rotary control knob on the station as a controller for setting the desired temperature on the iron's tip. The power station automatically keeps the iron tip at an appropriate temperature.

Some models have a digital display to show the current temperature of the iron tip.

It is easy to adjust the desired temperature - turning the knob clockwise increases iron's temperature while turning a knob counterclockwise decreases temperature. Some models of temperature controlled soldering iron come with "+" and "-" buttons instead of the control knob, so increasing heater temperature is done by pushing the "+" button while decreasing temperature is done by pushing the "-" button. The temperature of the iron can be precisely adjusted within 10°F with the front panel temperature control knob.

The wattage of these irons is usually in the range of 50 -70 watt. .

These soldering irons are more expensive than unregulated soldering pencils. The price for decent temperature controlled soldering irons on the USA market (including soldering irons that have very accurate electronic temperature adjustment) is in the range of 50 -150 dollars.

From this group, we recommend the following irons:

The third type of soldering irons is a complete soldering system for repair and rework.

This soldering system usually consists of a complete benchtop control unit where you can plug in a variety of soldering tools including temperature controlled soldering iron, hot air soldering gun, de-soldering gun, thermo–tweezers, stand for iron, etc. Thermo–tweezers are an excellent tool for removing surface-mount resistors and capacitors,

These soldering stations are designed for professional use, continuous production line, rework and repair stations in high volume manufacturing. They are also recommended for those who need to use a soldering tool regularly.

This is the most expensive type of soldering iron. The price for a professional soldering system (rework and repair) is in the wide range of 200- 2500 dollars.

From this group, we recommend Pace multichannel rework station MBT350.

Three different versions of temperature controlled soldering iron

In the first version, an operator can increase or decrease the voltage across the heater and therefore change the temperature of the iron tip. As we mentioned earlier,, basic soldering irons have constant voltage applied to the heater without the possibility to vary it.

In the second version, the temperature of the iron tip can be set with a temperature-controlled magnetic switch within the heater block. Here we have a small magnet that has been designed to lose its magnetic properties at a certain temperature. This magnet forms part of the switch within the heater assembly, and when the magnet loses magnetic properties (at a certain temperature) as result, the switch opens and cuts off the voltage to the heater.

The third version of temperature controlled soldering iron is a soldering iron that contains a temperature sensor built within the heater assembly. The operator sets the desired temperature for his soldering project and then the temperature sensor within heater assembly, through the feedback system, turns on and off the heater element to maintain the temperature at the desired level.

How to choose soldering iron

This article is about choosing soldering irons used for soldering electronic components and wires to circuit boards in electronics.

So, when choosing soldering iron for applications in electronics, consider iron wattage in the range of 30-70 watts.

Wattage

Wattage is a very important factor to consider when thinking to purchase soldering iron which is the best for your application.

The majority of temperature-controlled soldering irons available on market in the USA have a power rating of between 50-70 watts. Weller soldering iron WE 1010 has a power rating of 70 watts. Hakko FX-888 has also a power rating of 70 watts.

Basic soldering pencil without any temperature control capability have power rating starting with 15 watts.

Higher wattage does not mean that the soldering iron runs at a higher temperature. Desired temperature value of iron is set at iron’s base station and is maintained at that level all time during soldering Higher wattage of soldering iron means that iron has more “spare” power when soldering larger solder joints.

Temperature-controlled soldering irons recover faster to working temperature when dealing with heavy soldering work such as soldering thick wires together or too big connectors such as banana connectors or alligator clips.

Soldering wires on a too big and wide ground plane on a circuit board may require a lot of heat as well.

When attempting to solder large solder joints with a low-wattage soldering iron, thick wires or large component leads will draw heat away from the soldering iron cooling it down too much.

This will prevent solder to melt and flowing properly in the solder joint since low-wattage soldering iron does not have enough power to quickly recover. The result is a poor connection or cold solder joint.

Higher wattage of soldering iron allows you to work in a wider range of soldering tasks.

So, when choosing soldering iron for applications in electronics, consider irons which wattage in the range of 30-70 watts.

Voltage

Soldering irons are designed for use in many different countries. Different countries have different voltages in their power outlets.

That means that the same model of soldering iron has a few different versions and may be set for other voltages.

Make sure that your soldering iron runs directly from mains at 110 Volts A.C. In other words, check if your soldering iron is made for the USA market. This is very important when purchasing your soldering iron from online vendors in Europe or Chine.

Iron tips

Iron tips are available in a large range of shapes and sizes.

It is useful to have a set of spare iron tips in different sizes and shapes – you will be able to perform a wider range of soldering tasks.

Always use only those tips which are recommended by the manufacturer of the particular soldering iron.

A medium-sized chisel iron tip is used for soldering most of the through-hole electronic components, although a small number of specialized components may require a different iron tip.

Iron tips for soldering surface-mount components are quite different than iron tips for soldering through-hole components.

Surface-mount electronic components are much smaller than through-hole components so iron tips for soldering surface-mount components are much smaller.

They usually have a conical shape.

Many iron tips are shaped and sized to fit specific surface-mount components.

It wouldn't be possible to solder tiny surface-mount component with the same iron tip that is used for soldering through-hole components, for example with chisel tip 3/32”(2.38mm).

After some time you will find that you solder best with one particular shape of tip for the majority of your soldering projects.

Soldering iron ergonomics

Comfort is also an important factor when choosing which soldering iron to buy. Since soldering irons come in many different shapes and various types of designs, there is a lot of difference in soldering iron ergonomics.

Cheap soldering pencils typically come with a larger and thicker handle, which makes soldering more difficult especially when you solder for prolong time without break. You simply don’t feel right when holding uncomfortable iron in your hand.

If you are buying your soldering iron online, you will not be able to test it before purchase, but you can consider what shape of iron and diameter of handle you might prefer.

Auto shut off power

Most of the soldering stations come with auto shut-off power as a standard feature. This feature is adjustable, it is usually in the range of 0-99 minutes.

This is a good safety feature.

Spare Parts

When you planning to buy an expensive soldering station it is a good practice to find out if spare parts are available.

That way, if any part blows you may replace only that particular part and fix your exiting soldering iron – you don’t need to replace the entire soldering iron with a brand new one.

Digital Soldering Iron

Some models of temperature controlled soldering iron might have built-in digital temperature readout. The current temperature of soldering iron is displayed on digital readout all time during soldering.

As soon as you push one of the buttons to adjust the temperature of the heating element, the digital readout shows a set temperature.

When you are done with setting the digital readout switches back and shows the current temperature of the iron's tip.

Updated: February 09, 2024