The Study Of Dust Ingression Affected By Electric Field Of Devices And Experimental Simulation On Electric Contact Reliability

There are numerous electric contacts in electronics, electric-power and automatic control system. Their capability affects the reliability of electric and electronic devices directly. Lots of studies indicate that dust is one of the factors causing electric contact failures. Therefore the research of electric contact in dusty environment will improve the reliability of electric and electronic system. In this paper, the effects of dust particles on electric contact are detailed into two parts, one is the dust ingression, and the other is electric contact failures after dust deposition.The research of dust ingression mainly focuses on the electric field factors. Two-dimensional electro-magnetic models of finite element method were established using ANSYS software, simulated for mobile phones (3.7V). The electric field force after calculated is much smaller compared with the air flowing force and the gravity. This analysis proved the important results that the electric characteristic of electronic devices effects on dust deposition could be ignored, then relevant experiment are designed for analysis and verification. Extend to electronic Apparatus above 220V, the extreme ranges are given when electric filed are under the consideration.Dust deposition experiment is designed based on reliability theory, in order to research the process of electric contact failures. The criterion is given from the maximum of 200 dust tests on clean materials, and inserted probability of the dust is available.300/mm2 is gotten as the hazardous dust density that the inserted probability reaches above 90%. Furthermore, the curve fitting analysis of the inserted probability and dust density is discussed. The fitting result show that some functions are better forms, but the 4th polynomial and Power function is the best through analysis. Then contact resistance of 100mΩis given as the failure criterion in some field, and its probability fitting with the relevant dust density is given as the best form of the 2nd Gaussian function. Finally, two methods of curve generality analysis are discussed and its working area is given.