An electronic connector provides a separable interface between two subsystems of an electronic system. The contact spring is probably the most critical component in an electronic connector. Mechanically, the contact spring provides the contact normal force, which establishes the contact interface as the connector is mated. However, connector manufacturers have a basic struggle between the need for high normal contact forces and low insertion forces. Designing connectors with large numbers of pins that are used with today’s integrated circuits and printed circuit boards often results in an associated rise in connector insertion force. It is possible to lower the insertion force of a connector by redesigning the geometry of the contact spring, but this also means a decrease in contact normal force. In this paper, structural shape optimization techniques are used to find the optimal shape of the contact springs of an electronic connector. The process of the insertion of a PCB into the contact springs of a connector is modeled by finite element analysis. The maximum insertion force and the contact normal force are calculated. The effects of several design parameters are discussed. The geometry of the contact springs is then parameterized and optimized. The required insertion force is minimized while the normal contact force and the resulting stress are maintained within specified values. In our example, the insertion force of the final contact spring design is reduced to 68.3% of that of the original design, while the contact force and the maximum stress are maintained within specified values.

Silver particle (3 lm) carbon-matrix composites in the form of thick films (around 100 lm thick) on alumina, as prepared from pastes comprising silver and mesophase pitch particles (14 lm), have been attained. The films on alumina were fired at 650°C in nitrogen to convert pitch to carbon. The volume electrical resistivity attained ranged from 10 -5 X cm to 10 4 X cm, depending on the silver volume fraction. The percolation threshold was 12 vol% silver.

No abstract