A Summary Report on the Mechanism of Electric Contact Failure Due to Particle Contamination

Particle contamination may cause serious electric contact failure. However a series of dust simulation tests could hardly reproduce the real contact problem of intermittent high resistance, i.e. very few contact failure has been found during the tests. This paper is based on testing and analyzing many practical failed connector contacts in mobile phones. The special features of the failed contacts that are due to particle contamination are then summarized. The mechanism of connector contact high resistance failure is that during micro movement, contaminated particles are accumulated and inserted at the interface instead of being pushed away. Therefore important criteria should be met: micro movement with irregular directions, variable moving lengths to wear out surface materials, stirring up particles of dust and corrosion products caused by the water soluble salts in the dust, trapping the dust particles and thus embed the particles into the contact surface, presence of some organics acting as adhesives to adhere particles together to prevent them from spreading away during micro movements. Materials within dust particles such as quartz, feldspar, mica, calcite and carbon etc. may also contribute to the contact failure. After several simulation tests it is verified that contact failure can occur only if the testing conditions and parameters include the above discussed phenomena. The testing and theoretical result have greatly convinced that further research is necessary in order to create and develop a workable simulation dust testing system for connectors.