Formex GK Comparison to other materials

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 Formex GK vs…

Nomex or other aramid fiber - Nomex 410 is an organic aramid fiber based insulation that can absorb moisture through humidity or immersion. Absorbing up to 10% of its weight in moisture can cause Nomex to become dimensionally and dielectrically unstable.  Conversely, Formex will only absorb .06% of its weight.  The true benefit of Nomex is its ability to withstand temperatures up to approximately 480^oF (250^oC).  At 1/3 the cost, Formex can be used for most applications under 235^oF (115^oC).

Polycarbonate  – While having nearly the same temperature resistance and dielectric strength as polycarbonate (such as Lexan), Formex is far superior in its ability to be scored, folded and refolded.  Polycarbonate has a tendency to crack during cold forming, especially when exposed to harsh chemicals.  The cost of Formex is roughly 25% less than that of Lexan FR-700 Polycarbonate.  Polycarbonate is offered in a clear film version while Formex is only white or black.

Polyester - Though less expensive, polyester films such as Mylar are not UL 94 V-0 rated.  Many types of Mylar offered are UL 94 VTM-2 classified.  They also do not score and cold form well, partly because they are thermoset materials.  Polyester film does offer some advantages over Formex if very thin film is needed (less than .005") or a clear material is required.

PVC – PVC film is becoming less acceptable in design of new products as Europe has banned its use for electronics.  It obtains it UL 94 V-0 rating through the emission of poisonous chlorine gas that self-extinguishes the flame when burned.  It is still one of the least expensive films available but has temperature resistance and dielectric strength far lower than Formex.  It is also available in white or black but in fewer thicknesses.

Valox – Valox FR-1, by Sabic Innovative Plastics, (formerly made by GE Structured Plastics), is a thermoplastic polybutylene terephthalate.  Both Formex and Valox are useful in thin applications (down to .005” thick) as they both carry a UL 94 VTM-0 rating at that gage.  Valox has a dielectric strength about 30% lower than Formex and costs roughly 30% more.

Fishpaper or Cellulose Fiber Insulation – Paper and other fiber based insulations, while inexpensive can absorb as much as 60% of their weight in water, compromising their already low dielectric strengths (200-300 V/mil).  Often, Formex 1/3 as thick can be used instead, provide superior performance, and cost less than the thicker fiber/paper based materials.

Polyimide Film - Polyimide film, such as DuPont's Kapton HN offers true benefit in extreme temperature applications (-450F to +750F) where a very thin and durable material is needed.  Kapton feels much like a polyester film and has good dielectric strength.  With this extreme performance comes a premium price point.  Formex can be used for a fraction of the price in similar applications within a more moderate temperature range.