Continuous Coating Process for Magnet Wire Insulation, Phase II

In recent decades, advances in electronic components have led to smaller devices that generate significantly more heat per unit area. The processes by which waste heat is removed are less efficient, and the system must operate at higher temperatures. Magnet wire is a key component of many of these devices, and the durability of the insulating coating is critical to operation at elevated temperatures. Additional stresses on the wire insulation also come from the use of high-frequency, pulse-width-modulation control schemes. The integrity and lifetime of the magnet wire coating are therefore directly related to system performance and reliability. In previous work, Ultramet developed a rapid, low-cost method of applying oxide, nitride, and carbide interface coatings to carbon and silicon carbide fibers at low temperatures (as low as 100 degrees C) through ultraviolet-activated chemical vapor deposition (UVCVD). In this process, ultraviolet energy is used to decompose coating precursor gases at much lower temperatures than when thermal energy is used alone. The low temperature process has clear advantages over alternative coating methods because it is not line-of-sight and therefore can uniformly coat intricate shapes such as individual fine fibers. In Phase I, Ultramet established the initial feasibility of a continuous magnet wire coating process using low temperature UVCVD for applying a boron nitride high temperature insulating coating on copper wire. BN is an excellent electrical insulator. Although the potential exists to increase the insulating properties and use temperature of organic wire insulators to some extent by adding a BN powder filler, a much greater impact on electrical component use temperature can be achieved by using a pure BN layer. The non-optimized wire insulation coating applied in Phase I was shown to provide effective insulation at temperatures up to 370 degrees C. In Phase II, Ultramet proposes to further optimize the coating for maximum use temperature using low-cost processing and to demonstrate practical application within a high temperature electrical component, in conjunction with a commercial component manufacturer.