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Resistance Soldering Frequently Asked Questions

There are things here that you might not have thought of when it comes to resistance soldering. In among the answers to questions that we have received, you may find useful ideas.

There are four sections to this page. The first covers the questions, the secondĀ  shows free books on resistance soldering, the thirdĀ  contains an extensive collection of video tutorials on resistance soldering and the last an index of our complete series on resistance soldering.


How does resistance soldering work?

Resistance soldering works much like an electric stove. By passing current through a resistive material the material gets hot.

Utilizing the resistance of metals, soldering tips on resistance soldering irons generate high temperatures, rapidly, at localized points.

What are advantages of resistance soldering?

There are many!

  • Heat is localized at the point where the soldering iron tip touches the metal.
  • Localized heating is nearly instantaneous so nearby joints are not affected. The result is that you can make joints that you could not make with a conventional soldering iron.
  • Hobby modelers can solder photo etched parts, etched brass kits and other thin copper based metals without damaging them.
  • Eliminates the need for a torch. Not only is there no flame or burn hazard, because the heat is localized, there is no oxidation or fire scaling of the work and therefore no requirement for pickling.
  • Burn hazards are eliminated because soldering probes cool rapidly.
  • Removing enamel from magnet wire is fast and efficient.
  • They are particularly time efficient with solder paste. There is no need for flux, pre-tinning, or after soldering flux and excess solder cleanup.
  • Material and operating costs are lower.
  • If you use flux, you need less because flux activation is higher.
  • Solder use is lower because tip pretinning and conditioning is eliminated.
  • Power consumption is reduced. While conventional soldering irons are continuously on, resistance soldering irons are on demand units and that demand is typically only 1 to 4 seconds.
  • Power consumption can be lowered further by adjusting power to exactly what is needed.
  • Soldering iron tips and probes last longer.
  • Damage to heat sensitive parts is eliminated. This makes for efficient circuit board repair.

In short these are efficient, on demand units that allow for fine scale and general high quality soldering.


On What Type Projects Is Resistance Soldering Used?



Photo Etched Parts

Etched Brass Kits

Silver Soldering


Circuit Boards

Soldering In Positions Or Places That A Hot Soldering Iron Can Be A Burn Hazard

Anywhere You Need Heating Without Damaging Components Or Nearby Solder Joints

Note that resistance solderers are in reality variable power spot welders. You choose the power capability based on the work that must be done.

Are Resistance SolderingĀ  Irons Safe?

Most resistance soldering irons use low voltage AC current. Use of them is generally safe. One should, of course, always be careful when working with any electrical equipment – particularly if you have a medical condition.

Because they are heat on demand and the soldering probes cool rapidly, burn hazards are reduced to a minimum.


What Power Should I Use?

For craft and electronics work, 60va max is generally fine. Low range should be about 30va.

Craft work includes jewelry, silver solder and photo etched part work.

For industrial type applications, it is best to discuss your particular requirements with a resistance soldering supplier.

Are DIY Resistance Soldering Irons Safe?

There are two aspects to this. Are they safe for the operator and are they safe for the piece to be soldered?

The heart of a resistance soldering iron is the transformer. Using a transformer for a purpose other than that for which it was designed is STRONGLY discouraged. The taps off the secondary winding may create probe va values that will either damage your work or not be high enough to make the solder joint. Additionally the wiring may end up being dangerous.

Use only a commercially made transformer rated for your needs. Commercially made transformers normally are made in compliance with all regulatory requirements and they will have secondary taps that suit your particular power requirements.

For a craft user, we recommend you look here.. There are, of course, other transformer suppliers out there. But this is the one that we use.


Do Resistance Soldering Iron Tips Need Either Conditioning Or Tinning?

No. The best resistance soldering iron tips are carbon rods. The only conditioning that they need for most efficient work, prior to each use, is a wipe with steel wool or scotch brite to keep them clean.

This can add up to a significant savings in solder costs.

How Do I Keep From Breaking Resistance Soldering Iron Tips?

Too much pressure is the cause of tip pressure. Clean tips do not require pressure to make a good electrical connection. Clean the tip with scotch brite or steel wool before making a joint.


How Do I Check The Power Of My Resistance Soldering Iron?

Power is a function of voltage and amperage.

Use a multimeter to check the voltage between the probe and probe ground.

Then check the current.

There are many videos on the web to show you how to make each of these measurements.

What Is The Cheapest Way To Get A Resistance Soldering Iron?

Make your own. Watch YYYYYYYYYYYYYYYY

Get a kit to make your own resistance soldering iron here.


The books shown here are excellent reference books that beginners and experts alike will find useful. They are highly recommended. Try at least one now. Click on the image.

how to make a resistance soldering iron book cover resistance soldering frequently asked questions book cover resistance soldering book cover


Resistance Soldering Video Tutorials

Resistance Soldering Tutorial Library

About DIY Resistance Soldering Irons

Why Resistance Soldering Instead Of Conductive Soldering

How to build your own DIY resistance soldering unit. –

How To Make And Use Resistance Soldering Pickle

Resistance Soldering Frequently Asked Questions

How To Make Resistance Soldering Iron Tools

Resistance Soldering Tips And Hints




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