Nylon vs.Polyesterimide Taped Litz Wire: 

TThere are three aspects that need to be compared between the nylon serving litz wire and the polyesterimide (PI) taped litz wire.

To counteract skin effect litz wire is a requirement in high frequency electrics. Two options for insulation surround the air core litz wire: First is the Teflon or nylon fusing yarn, which is applied as a ribbon like to the litz wire.
Similarities

Twisted together to minimize AC losses: Both litz wires are composed of multiple strands of enameled copper wire that are twisted together. Added layer of strength and flexibility.Each litz wire has an extra outer layer that enhances electrical safety and good flexibility, they are applicable for winding.

Key Differences
The key difference being the purpose of the insulation for nylon serving litz wire and polyesterimide (PI) taped litz wire.
Taped litz wire is the litz wire wrapped with a film, one of the films is polyimide, it's the best insulation film, it provide high thermal rating, and increasing the dielectric strength – round wires can withstand over 6000 V, if the taped litz wire is processed into rectanglar form, the standard voltage standoff can still achieve at least 3500V, it far beyond the nylon serving litz wire.

Applications of Nylon Serving and Polyesterimide Taped Litz Wire

Nylon serving litz wire is very suitable for familiar high frequency transformers, wireless charging coils etc,– particularly where vacuum impregnation with varnish is necessary, since the nylon serving facilitates good resin penetration. Some nylon serving litz wires have a minimum standard withstand voltage as high as 1300 V. 

PI taped litz wire is widly used in high‑voltage and high‑reliability fields: on‑board chargers and DC/DC converters in electric vehicles, transformer, aerospace power supplies, and any system requiring VDE‑certified reinforced insulation and long‑term reliability under high stress.

Selection Guide

Choose nylon serving for general‑purpose HF designs where cost, flexibility, and impregnation compatibility matter, and where voltages stay below 1300 V. Opt for PI taped litz wire when your design demands high voltage (>6000 V), or reinforced insulation. The right choice hinges entirely on your voltage and reliability priorities.