About Round Enameled Copper Wire

  • Round Enameled Copper Wire is a kind of winding wire, usually made of copper or aluminum, insulated with enameled wire, used to make windings and coils. Litz wire is usually made of enameled wire. Despite its simple appearance, enameled wire is a complex product. The enameled wire must withstand the mechanical stress caused by bending and stretching during the winding process of the coil, which is usually carried out at the fastest possible speed to increase productivity. In addition, during normal operation (and overload events), mechanical forces, thermal stresses, and chemical and environmental conditions require wires and their insulation materials to have a certain level of performance so that a reasonable service life can be expected. The technical parameters of commonly used brands are standardized in accordance with international standards, such as: IEC 603176), NEMA MW10007) and JIS C32028). For example, for round enameled wire, define or control the following parameters: Size (diameter) insist Mechanical flexibility (crack resistance of enamel) Elongation (due to the tension required during the winding process) Thermal shock resistance Rebound (after bending) Dielectric breakdown strength (Tooth enamel) fully cured Solderability (easy to apply solder directly through enamel) Thermoplastic flow (cut in) Solubility Transformer oil resistance and hydrolytic stability key Heat resistance Scratch resistance of enamel Quality loss resistance Lap shear bond strength Enamel performance In addition to electrical insulation, enamel can also prevent corrosion or oxidation of copper wires. The typical electrical strength of enamel is about 170-220 V/μm, which is why a relatively thin layer of enamel can withstand high voltages. For example, the 0.375 mm wire with a cracked enamelled wire shown above has a breakdown voltage of 4.35 kV even though the enameled thickness is only 0.0275 mm. The life of electrical insulation is related to its use temperature. The typical shortest life of enamel at its nominal temperature is about 20,000 hours. There are several nominal temperature ranges (heat levels), which list the basis for making enamel, such as: 155-180°C-Polyurethane (good solderability at 370-390°C) 180-200°C-Polyesterimide (good heat resistance and chemical resistance, can be soldered above 470°C) 220°C-Polyamideimide (good heat resistance and mechanical properties, not solderable through enamel) 240°C-Aromatic polyimide (very good heat resistance, chemical resistance and radiation resistance, can not be welded by enamel) welding The enameled wire of this common mode choke coil is directly soldered to the PCB using the "self-melting" characteristic of the enameled, without the need to remove the coating by any mechanical means. The presence of enamel hinders welding (compared to bare copper). For this reason, the chemical properties of the enameled wire are optimized to facilitate soldering (especially for enameled wires rated up to 200°C), which can be achieved by applying heat and solder directly to the outer surface of the enameled wire. The enamel will dissolve or evaporate, exposing the copper underneath, and to some extent provide even some fluxing or self-melting properties. This is sometimes indicated in the product name, such as "Polysol" by Elektrisola. Enamel with a higher temperature rating does not support the function of direct welding to copper. Instead, the coating must first be removed by some mechanical means. Self-adhesive enameled wire There are also special grades of enamel for specific applications. For example, there is a "self-adhesive" type of enamel, which has an additional layer of adhesive. After winding into a circle, the formed wires can be bonded to each other by activating the adhesive or heating components with a solvent. The coil can be heated using thermal methods (depending on the type of adhesive), usually to about 120-220°C. By: blowing hot air on the component and putting it in the oven, or by the "resistance method" (the current Heating by coil). Using the solvent method, the adhesive can be activated by applying (brushing, spraying or wicking) a suitable solvent (such as denatured alcohol (ethanol or methanol)) during the winding process. The solvent can be diluted with water as needed, but it will reduce the adhesive strength. score Enameled wire is usually divided into three "levels", the number of which is related to the thickness of the enameled bag (usually assumed to be the number of coatings): Class 1-Thinnest insulating material, single layer Class 2-Medium insulation, double layer Class 3-the thickest insulating layer, three layers Class 3 enameled wire should not be confused with triple insulated wire. For example, the size comparison of 0.5mm enameled copper wire. Higher levels of voltage breakdown increase significantly, but at the expense of thicker insulation and the outer diameter of the wire (so fewer wires can be installed in the same cross-sectional area of ​​the winding).