Research Of Test Methods On The Influence Of Dust To Electric Contacts

The contact failure, most of which are caused by dust particles in the atmosphere, widely exists in electric equipments nowadays. A research on connectors in the failed communication terminals shows that over 65 percents of all the contact surfaces are polluted by dust, and nearly 50 percents have dust accumulations. During the operation of connectors, dust particles in the atmosphere can be brought to the contact interfaces, and contact reliability problems may appear. So it is very important and necessary for us to research the influence of dust on electric contact.To research the influence of dust on electric contact, the contact resistance of dust polluted connectors has to be measured. The very first problem we need deal with is dust observation and location problem, which is how to move the probe right onto the dust particle. In this paper, a mini-microscope system was adopted, it was proved in the mathematic way that all the design goals were achieved, for example the magnification of this system was 120, the resolution was 6μm, the depth of field was 23.2μm and the angle of vision was 10°.We also studied the process of dust locating based on the precise relocation contact resistance testing system and mini-microscope system. A testing method and the steps on the influence of dust on static contact resistance were proposed. We also focused on how to choose the experiment dust, how to disperse dust, etc. By experiments, we proposed an experiment step flow, which could be used as guidance of following research on influences of various dust particles to static contact resistance.Theoretical analysis indicates that there is a hazardous size range of the dust particles within which dust particles can cause contact problems even the density is small. In this paper, we talked about how to verify this size range of various dust particles based on the fretting test system and mini-microscope. An experiment step flow was also proposed and experimentally proven.The mini-microscope system makes it possible to observe the mini-size dust particles around the contacts during resistance testing. It is a good way to precisely research the influence of dust on both static and dynamic contact resistance.