Fully Insulated Wire (FIW) is a wire product that can replace traditional TIW (Triple Insulated Wire) for the production of switching transformers. Due to the wide selection of finished FIW outer diameters, it allows customers to produce smaller transformers at a lower cost. At the same time, FIW has better winding performance and soldering performance than TIW.
FIW adopts a multiple coating process and has undergone more than 30 coating treatments to ensure reliable and defect-free insulation.
FIW’s insulating material is based on an improved polyurethane, which has a working life of 20,000 hours at 180 °C according to the IEC 60172 standard. The FIW production process has multiple separate insulation coatings and online high-voltage continuity tests to ensure reliable and defect-free insulation.
FIW defines different levels to specify varying insulation thicknesses: FIW3, FIW4, FIW5, up to FIW9. For example, FIW3 0.050 mm wire has a maximum total diameter of 0.072 mm with 3,000 volts breakdown voltage. FIW8 0.050 mm wire has a maximum total diameter of 0.127 mm and a minimum 8,000 volts breakdown voltage.
Advantages of FIW
- Different insulation layer thicknesses can be selected, allowing product optimization such as reducing transformer size and cost
- Excellent solderability
- Excellent windability
- Based on IEC 60172, FIW can reach a high temperature class of 180 °C
- Heat resistance of 0.10–0.71 mm wire diameter tested per UL 2353 appendix U obtained Class B (130 °C) and Class F (155 °C) certification; 0.10–0.50 mm also obtained reinforced insulation certification at 155 °C
- UL insulation system certification for enameled wire, with safety verified through years of use
FIW Technical Value
FIW technical value in accordance with IEC 60317-56. FIW is typically a 180-class enameled round copper wire with a single-layer coating based on polyurethane resin. Specifications and technical data generally match the P.Leo catalog number FIW (MW85-C) and UL file number E158033 in accordance with IEC 60317.
However, due to special requirements for weldable wires with fully insulated zero defect, some specifications extend beyond the previous scope. Special technical values are specified in IEC 60317-0-7 and IEC 60317-56. P.Leo FIW meets and exceeds the FIW requirements of IEC 60317-56.
FIW technical value in accordance with IEC 60950 Annex U. Specific requirements for FIW test conditions appear in standard IEC 60950 (Annex U) for safety of information technology equipment. P.Leo FIW results shown on page U of the IEC 60950 Annex demonstrate compliance with IEC 60950 (Appendix U) requirements.
IEC 62368-1 integrates the IEC 60950-1 and IEC 60065 standards, released in 2014. As equipment and applications develop rapidly with converging technology, IEC 62368-1 increases requirements for fully insulated winding wires (FIW).
| Test Parameter | Test Method | Spec Value — 0.30 mm FIW6 | Typical Value — 0.30 mm FIW6 |
|---|---|---|---|
| Mechanical | |||
| Elongation | IEC 60851-3.1 | ≥23% | 56% |
| Tensile strength | IEC 60851-3.2 | Not specified | 310 N/mm² |
| Springback | IEC 60851-3.4.1 | Not specified | 68° |
| Solderability | |||
| At 390 °C | IEC 60851-4.5 | ≤4 s | <3.0 s |
| Thermal | |||
| Temperature index | IEC 60172 | ≥180 °C | 192 °C |
| Heat shock | IEC 60851-6.3.1.1 | ≥200 °C | 220 °C / 6 mm mandrel |
| Cut-through | IEC 60851-6.4 | ≥245 °C | — |
| Breakdown voltage (air-filled) | |||
| Volts | — | 10032 V | > 15 kV |
| Room temperature, V/µm | IEC 60851-5.4.3.2 | min. 76 V/µm | > 100 V/µm |
| At 180 °C, V/µm | IEC 60851-5.4.3.2 | min. 53 V/µm | 74 V/µm |
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