FIW vs TIW – Which Insulated Wire Is Right for Your Transformer Design?

To begin with, in terms of structure: FIW wire is multi-layer coating. It is made up of multiple coats of insulating varnish, forming a very thick insulation layer which is treated as a single conductor. In contrast, TIW wire( triple insulated wire) is made of three separate layers of insulation, which is an extrusion process, and you can easily identify the three layers from the structure.
Secondly, on the temperature rating: FIW wire can be used at temperatures as high as 180°C, and TIW wire comes in two temperature ratings of 130°C and 155°C.
Third, solderability: It is possible to solder FIW wire directly at high temperature (about 390°C) without removing the film of insulation, but TIW wire must be stripped either manually or mechanically before soldering.
Finally, on the advantages of each type. FIW wire has the advantage of a smaller overall diameter for transformer miniaturization, and better solderability and more options for the thickness of insulation. TIW wire has a three-layer independent structure with more reliable insulation performance and is relatively matured technology.
However, FIW reconstructing also has a number of challenges and limitations to successfully replace TIW:
1. Strict safety standards testing: Following IEC 62368-1 the FIW-based transformers have also to be tested to a number of extra tests, making design and certification more complicated. Thermal cycling test: It takes about 36 days and temperature cycling under load condition. * Partial discharge test: It is compulsory to take this test in case peak voltage across the insulation is more than 750V. Scope of application: FIW is only for tools in the overvoltage category OVC I or II, but not for OVC III or IV.
2.Industry and process maturity: Others argue that the FIW industry is gaining enough regulation and that its manufacturing method is that of an immature process compared to that of TIW wire. In reality production,high temperature conditions (such as too high reflow soldering temperature) can result in wire melting damage and other hazards.
Ruiyuan offers both TIW wire and FIW wire, we look forward to your inquiries!