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Electrical Insulators

Kapton Insulator

Kapton Insulator

Die-Cut Insulators were one of NEDC first products. This product line went along with gaskets as some of the first parts NEDC cut for customers. When NEDC first started, most electrical insulators were die-cut. However, with the new machinery that NEDC employees, waterjet, laser, and other machines also play a part.


Many of the materials used for electrical insulation are also used on our other products. In other words, gaskets, and thermal pads may also isolate an electrical current. As a result, materials including plastic, thermal interface pads, rubber, and paper like products all may have the ability to be electrically isolating.

Thermal Pads

One of NEDCs core products are thermal pads. For that reason, its interesting that thermal pads oftentimes serve as electrical insulators. Products such as Sil Pad®, and Gap Pad®, are marketed because of their high volume resistivity making them ideal for electrical insulation while providing a thermal management solution.

Many Gap Pad® products offer electrically insulating properties. Gap Pad® products such as GPVOUS, GPVOS, GP5000S35, GPHC3.0, GPHC5.0 offer high levels of electrical insulating properties. This is in addition to their thermally conductive properties as well.

Many Sil-Pad® products offer electrically insulating properties. Sil Pad® products that are electrically isolating include Sil-Pad 900S, Sil-Pad 2000, Sil-Pad 400, and others.

Thin Plastics

Many thin plastics that NEDC cuts are electrical insulators. Materials like Kapton®, Mylar®, Lexan®, Formex®, G10/FR4 Epoxyglass all may serve as electrical insulators. These plastics can be converted into die-cut insulators.

Mylar® is a polyethylene terephthalate(PET) that is registered by DuPont. These materials usually come in thin films ranging from .002” to .014” in thickness. It is commonly used as an electrical insulator. MYLAR® A is the most common type. Mylar® MO is approved for Class B insulation.

Kapton® is a polyimide film that is registered by DuPont. This plastic can be certified to MIL-P-46112 Type 1, and ASTM D5213 Type 1 Item A. It usually comes in thin formats such as .0005” to .005” in thickness. Anything above this enters into the category of Cirlex®. Common applications include insulation blankets, and insulation tubing. There are a few different types of Kapton Film besides Kapton HN. These include Kapton® FN, Kapton® FWR, Kapton® GS,  Kapton® MT+, and Kapton® RS.

Lexan® is a polycarbonate plastic that is oftentimes die-cut in film form. Lexan® plastic is a registered trademark by SABIC. Lexan® is extremely tough, but is formable. There are many different types. However, NEDC mainly die-cuts 8010, FR700, and others.

Formex® is a flame retardant polyproylene plastic. Formex® has excellent electrical properties. This plastic is fungus inert. There is GK-5, GK-10, GK-17, GK-30, GK-40, and GK-62. These plastics run from .005” in thickness to .062”.

Epoxyglass/G10/FR4 is a plastic like material that is really laminated glass with epoxy bonding it together. These materials are oftentimes used as electrical insulators. Most often NEDC die-cuts these materials, the thickness is below .015”. G10 is generally not thought of flame retardant. However, FR4 is flame retardant. MIL-I-24768 encompasses many different options. G10 being /2, and FR4 being /27. These materials are generally available .005”-many inches thick.


At NEDC we cut many rubber materials to make gaskets. However, rubber materials can also sometimes serve as electrical insulators. For example, silicone rubber is a great electrical insulator that is commonly used in cables or wiring. Some other rubber materials used for electrical insulation include fluorosilicone, neoprene, EPDM, or urethane.

Silicone Rubber is commonly used as an electrical insulator. In fact, this material is probably the most commonly used material at NEDC. We use silicone rubber for gaskets, insulators, vibration dampening, and many other uses. Common certifications include A-A-59588, ZZR765, and others.

Fluorosilicone Rubber is another commonly used electrical insulator. However, it is not as commonly used as silicone because of its other qualities that tend to make it more expensive. Some specifications include MIL-R-25988, AMS-3329, and others.

Neoprene Rubber is a synthetic rubber also another commonly used electrical insulator. It is used in cable jacketing for wire and cable. It is often flame resistant.

Paper like Products – Die Cut Insulators

Many paper like products serve as electrical insulators. Some common ones that NEDC sees are Nomex®, Fishpaper, Kraft Pulp, and others.

Nomex® is a aramid fiber paper. It has a high dielectric strength. This paper is used for The most common type of Nomex® is Nomex 410. Nomex 410 comes in a number of thicknesses ranging from .002” to .030”.

Fishpaper is an electrically insulating paper that is resistant to heat. It is an excellent insulator used in fuse tubes, and electronic devices. Thicknesses of fishpaper range from thin (.005”) to thicker (.030”). Specifications include MIL-I-495. It mostly comes in dark colors such as gray, or dark blue.

Electrical Qualities to look for with Die-Cut Insulators

Volume Resistivity

Volume Resistvity plays a huge part in die-cut insulators. The higher this number the better. A low number indicates the materials conductivity. This number indicates how much the insulator resists electric currents.

Dielectric Strength

Dielectric Strength is an important metric with die-cut insulators. It helps determine the quality of the insulator. It is defined as the maximum voltage required to produce dielectric breakdown through the material. All the materials above would register a high dielectric strength, for example.

Different Custom Gaskets

Thermal Pad, Silicone, g10, Sponge


As with most materials NEDC provides, adhesive backing is available on certain products. Some common tapes we use from 3M are acrylic based 9485PC, 9472, 467MP, and 9469PC.  For more information on electrical insulators, or you believe you have a project that could use a die-cut insulator, please contact sales@nedc.com.

Electrical Insulators Blog
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All of the information presented above is believed to be factual and accurate; however, NEDC is not liable for any design or application utilizing this information.

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