Polyimide is one of the most heat resistant polymers with high electric breakdown strength, good mechanical properties, and chemical resistance. Polyimide is used in severe environmental condition. Polyimide is commonly applied as electrical insulation in a fine gauge of invertered motor windings and in high voltage coils of encapsulated fly-back transformers. The wire insulation may be exposed to multi-stresses like ac, dc high voltages, temperatures etc. In this thesis, magnet wire insulation properties under multiple stresses are studied under ac, dc voltages and high temperatures. Accelerated degradation test is used to do study of Life -time characteristics of Magnetic wire MW 16-C, which has polyimide insulation. The results of accelerated aging test are evaluated with statistical tools Weibull and ALTA. The result shows that the time to failure can be represented by the inverse power law and the Arrhenius equation with respect to test voltage and temperature respectively.

Abstract not only influence on development of basic industries in a country but relate with business cycle. Hi-tech industries grow rapidly and play a key role with ¡§innovation¡¨ in stock market. The trends of hi technology make people forget that traditional industries not only keep existing but play a great role of economic activities. Historically speaking, Electric wire and cable industries still exist and even stably develop.¡C I hope to apply the following theories including innovation management, dependence of resources and product life cycle to explain why traditional industries are not sunset industries. Besides, I also chose Feng-chin Corporation as a case with best skills at magnet wire manufacturing to explain how a company keeps his competitive advantages in the matured market. Through case study and theory applied, the followings are concluded. 1. With less possibilities the products are replaced, the greater possibilities of continuity of the industry. In aspects of attributes of product itself, no alternatives appear to substitute for the copper and therefore the magnet wire industry would not disappear as the raw materials with the copper. Even though we can find the new material to replace the copper, the magnet wire industry will still exist with other alternative to replace the copper. When PLC model are applied, the products with greater continuity represent highly matured products. Hence, the products with greater continuity have the following characteristics including less possibilities to be replaced, highly matured and unclear decline stage, and high dependence of the below companies. 2. In low value added industries, individual company should emphasize on process innovation and diversified customers. The Feng-chin Corporation struggles to innovate technologically and in process by the following ways. (1) They make traditional products into hi-technology industries by raise added values. (2) They concentrate on costing down and their own field (3) They well utilize their resources to enforce the mutual-depend relationship with the below companies. Likewise, in the industries which pursue economic scales to reduce the cost, it is more important to diversify the costumers when they have the following characteristics including high matured products, high pricing products and lower mobility of the equipments. Key words: innovation management product life cycle magnet wire industry continuity

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