F.D. Sims Limited: Solderable Polyurethane Enamel Round Wire Technical Page

Solderable Polyurethane Enamel Round Wire is covered with a modified polyurethane resin which was introduced to combine excellent dielectric strength and pin hole resistance with the advantage of soldering without prior removal of the element from the wire. This factor makes it most useful for multi-connection windings as it eliminates costly stripping operations, especially on finer wires.

Specification

Solderable Pu Wire has a very low power factor which shows little change at high frequencies or under humid conditions. It possesses excellent flexibility and adhesion and has good pinhole resistance. Its windability, due to careful selection and processing of the copper, is excellent.
This wire meets the proposed draft requirements of EN60317-51.

Health and Safety Note

In common with all polyurethane enamels, Solderable Pu may produce minute quantities of Methylene Isocyanate (M.D.I.) on soldering. As the maximum allowable concentration of this gas is 0.005 parts per million, it is strongly recommended that fume extraction equipment be installed in the area where soldering is carried out. (For the method of measuring M.D.I. concentration see HSE Publication MDHS 25 Methods for Determination of Hazardous Substances - Organic Isocyanates in Air).

Chemical Properties

Solderable Pu will withstand the normal solvent combinations used in the majority of impregnating varnishes.

Temperature Classification

Solderable Pu Wire is suitable for use in Class H Systems provided that a suitable and correctly applied impregnating varnish is used and that all other associated insulating materials are of the same classification.
However, as is well established, this classification is dependent upon other factors, especially the nature of the operating environment. When evaluated in accordance with the procedures laid down in I.E.C. Publication 172 this covering has a Temperature Index on 185°C. It should be noted, however, that this wire covering can be damaged by overload temperatures which exceed 240°C.