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What is Litz Wire?

Litz wire is a type of cable formed by combining multiple strands of thin insulated wire together side by side. It is used to carry high frequency currents as the insulated strands each carry a portion of the current and prevent losses due to the skin effect. Litz wire is commonly found in radio frequency (RF) applications, and high frequency power circuits such as induction heaters and Tesla Coils.

The strands in litz wire are typically twisted together either as a single bunch, or as multiple bunches twisted to form a large cable. By twisting the wires together it helps to control the magnetic fields around the wires and keep the currents flowing evenly.

What is the skin effect?

She skin effect is a term given to the phenomenon of when high frequency currents tend to flow near the surface (or skin) of an electrical conductor. This occurs due to magnetic fields being induced in the conductor by the changing currents. The magnetic fields make it difficult for the currents to flow anywhere but the outer surface.
 
With the currents being forced to flow in just part of the conducting wire, the effective resistance of the wire is greater. The higher the frequency, the more loss in the wire due to this resistance.
 
By using this skin effect calculator, we can see that at a frequency of 1MHz, the effective skin depth is just 65μm (0.065mm), while at 1kHz, the effective depth is 2062μm (2mm) in a copper wire. 
 

How to make litz wire

Using common magnet wire it is possible to make your own litz wire by twisting it together in bunches. It is not practical for large numbers of strands but is doable for short lengths with a small number of individual wires.

The simplest way is to cut equal lengths of the required magnet wire and to clamp or tie all of one end together. The other ends can be put in the chuck of a hand drill which is used to twist them tightly together.

How to solder litz wire

It can be very difficult to solder litz wire as they can contain thousands of individually insulated strands. It is necessary to remove this insulation before soldering can take place. This can be done by first burning the end to be soldered and then cleaning of the burned insulation with wire wool. Doing this without breaking the fine strands or leaving some of them uncleaned can be quite challenging.

The best way is to use a hot solder bath as this can both burn off the insulation and add the solder. The solder bath must be quite hot and it works best if the litz wire is first dipped into flux to help the solder to stick.

Where can I buy litz wire?

We have a range of litz wire sizes for sale and offer soldering services for ready to use litz cable assemblies. If there is a specific size you need that we do not stock, we can custom make it to your requirements.

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