Film Insulations

What is Magnet Wire?

The term “magnet wire is used to describe solid conductor wire—usually copper—insulated with a polymer-based film. The films are designed to provide a uniform dielectric coating while taking up as little space as possible.

In specifying a magnet wire, there are several areas an engineer needs to be concerned with including:

  • Size or Diameter
  • Insulation Thermal Class
  • Insulation Build or Thickness
  • Color and Coatings

All the magnet wire used in manufacturing our Litz wire is certified to the most rigorous requirements of federal, NEMA and military specifications.

The chart below displays some commonly used magnet wire film insulations.  Please note, this is not an exhaustive list and other options may be available for your project. 

InsulationTemperature RatingAWGAdvantagesConsiderations
Polyvinyl FormalClass 105C
MW 15-C
14 - 50- Excellent abrasion resistance
- Excellent compatibility with transformer oils
- Good electrical proper ties
- Used in Cryogenic Applications
- Must be stripped before soldering
- Should be annealed before
application of varnish
PolyurethaneClass 155C
MW 79-C


Class 180C
MW 83-C
30 - 50


24-50
- Excellent electrical properties for high "Q" coils
- Easily solderable 390C/360C
- Excellent film adhesion & flexibility
- Good moisture & chemical resistance
- Not recommended for applications with the possibility of severe thermal overload
Polyurethane-NylonClass 155C
MW 80-C


Class 180C
MW 83-C
10 - 46


25 - 46
- Good electrical properties
- Easily solderable 430C/390C
- Excellent film adhesion & flexibility
- Improved chemical & mechanical resistance from nylon topcoat
- Nylon overcoat provides low coefficient of friction
- Not recommended for applications with the possibility of serve thermal overload
- Nylon topcoat is hygroscopic
Solderable PolyesterClass 180C
MW 77-C
14 - 50- Solderable 470C
- Excellent thermal proper ties
- Good electrical proper ties
- Good compatibility with varnishes & solvents
- Improved thermal overload
- Good moisture resistance
- Low abrasion resistance compared to Nylon & amide imide topcoat materials
- Preheat before varnishing is recommended
Solderable Polyester NylonClass 180C
MW 78-C
14 - 50- Solderable 470C
- Excellent thermal proper ties
- Good electrical proper ties
- Good compatibility with varnishes & solvents
- Improved thermal overload
- Good moisture resistance
- Nylon overcoat provides low coefficient of friction
- Nylon topcoat is hygroscopic
- Preheat before varnishing is recommended
Polyester
Amide-Imide
Class 200C
MW 74-C
34 - 44- Excellent flexibility & abrasion resistance
- Excellent thermal overload
- Excellent dielectric strength
- Excellent moisture resistance
- Good chemical resistance
- Must be stsripped before soldering
- Not recommended for use in oil- filled transformers
- Preheat before varnishing
Polyester/Poly-amideimideClass 200C
MW 35-C
8 - 33- Excellent flexibility & abrasion resistance
- Excellent thermal overload
- Excellent dielectric strength
- Excellent moisture resistance
- Good chemical resistance
- Must be stripped before soldering
- Preheat before varnishing
PolyimideClass 240C
MW 16-C
10 - 30- Excellent flexibility
- Excellent thermal overload
- Excellent dielectric strength
- Excellent moisture resistance
- Excellent chemical resistance
- High dielectric strength
- Adequate abrasion resistance
- Low outgas
- Must be stripped before soldering
- Must be annealed before varnishing
- Will solvent craze

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New England Wire Technologies is a privately held, employee owned company with a rich history dating back to 1898. Our Lisbon, NH facilities consist of over 385,000 square feet of manufacturing, quality/testing, tooling/machine fabrication, and office space.

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130 North Main Street

Lisbon, NH 03585

Phone: (603) 838-6624
Fax: (603) 838-6160

Email Us: info@newenglandwire.com