NFC 31 670 : 1988

Specifies the requirements of solderable enamelled round copper winding wire of class 155 with a sole coating based on polyurethane resin, which may be modified as long as it retains the chemical identity of the original resin and meets all specified wire requirements. Covers the following range of nominal conductor diameters: 0,018 mm up to and including 0,800 mm (Grade 1); 0,020 mm up to and including 0,800 mm (Grade 2). Coverage includes dimensions, elongation, heat shock, solderability, loss of mass, springiness, temperature index, breakdown voltage, and packaging.