scope:

Definition of performance requirements. Advice is given on defining the performance requirements of gasket/flange systems by reference to the performance requirements of the host equipment. Those requirements having a particular impact on the EMI seal design are identified.The need to integrate that design with the overall host equipment design is explained. The importance of participaing in the management and planning procedures of Def Stan 59-41, which ensure the required equipment EMC performance, is stressed.

Gasket/Flange systems. The comparative performance of the following five gasket types, as components in an EMI seal, is considered qualitatively:

(a) Conductive polymers.

(b) Wire mesh with or without polymer.

(c) Oriented wires in polymer.

(d) Expanded or woven mesh with or without polymer.

(e) Formed metal strips.

The chemical, electrical an1 mechanical properties of the flanges retaining those gasket types, is discussed is relation to the performance requirements of the EMI seals to be designed.

Performance testing. Some guidance is given on the degree of testing to be specified in gasket procurement. Attention is drawn to the importance of performance evaluation testing during equipment development.