Soldering Iron Not Melting Solder

This page assumes that your soldering iron is turning on and producing some heat, but is just failing to melt solder effectively. If your soldering iron isn't heating up at all, we've got a different page for that instead.

Many issues with soldering or soldering irons can be the result of improper usage. Make sure your soldering iron hasn't just gone to sleep and needs to heat up a bit. Some Irons can do this to save wear and tear on the tip.

You may be trying to feed solder to a part of the tip that is cooler than other parts. The side of a conical tip is the best place to feed the solder and to hold against the joint; the sharp tip may be too cool.

Check out our Soldering Best Practices to ensure you aren't the problem.

Many soldering irons are temperature adjustable. If your soldering iron has this feature, ensure the temperature is set correctly for the solder and components you're working with. Make sure it is warmed up too.

• Set it to 300 °C (~570 °F) if you're using leaded solder
• Set it to 375 °C (~700 °F) if you're using lead-free solder

You may have to adjust these values slightly depending on what you're soldering. Components with a large thermal mass such as metal connectors, thick wires, or power resistors require a higher temp to form a good solder joint. Small components, especially surface mount require a lower temperature to prevent heat damage.

Best practice for tip maintenance is to "tin" the tip of your soldering iron after each use by melting a small amount of solder over the tip. This prevents oxidation, which can hinder proper heat transfer. Sometimes your soldering iron may act as though it won't melt the solder, but it might be heavily oxidized and need some TLC. This isn't common but here's a guide to the process.

If the iron has been sitting for extended periods of time without being tinned, visible oxidation or corrosion is apparent on the tip, or the tip is otherwise cracked or damaged, replace it.

Sometimes the heating element inside the soldering iron or tip will partially fail, and not allow the soldering iron to get hot enough. Remove the tip and inspect the heating element for any cracks or damage and replace it if necessary. If you can't see any damage disassemble your soldering iron and replace the heating element.

On some irons the tip will be part of a cartridge assembly. If you have a cartridge-style soldering iron try replacing the tip cartridge. Some soldering stations will give an error if the heating element has failed.

The temperature control on your iron may fail, either the sensor or the control itself.

Higher quality soldering irons work on a controlled temperature principle. They have a sensor (usually a thermocouple) integrated in the tip heating portion, and an electronic control that uses the thermocouple signals to match the tip temperature to the settings on the iron.

If the thermocouple is damaged or the wiring fails, the iron may not heat. The control circuitry itself can be the problem as well. Unless you can obtain another control board, or are ready for board level repairs, this can be a game ender. You can try changing the heater portion since that will give you both a new element and a new sensor. If that doesn't work the control circuitry is likely at fault.