Abstract :
Electronic systems are almost invariably built with a hierarchical structure, and testing procedures and Automatic Test Equipment (ATE) have been developed to permit verification of correct operation of the system and of its component modules at all levels of the hierarchy. As circuit complexities increase, it has become increasingly clear that circuits have to be designed to suit the ATE if the testing costs are to be contained to an acceptable level. Developments in electronics over the last few years have not brought about any fundamental changes in circuit techniques or basic circuit components. There have, however, been dramatic changes in a number of aspects of mechanical technology. These changes impact in many different ways on the demands placed on the ATE and hence on the strategies that need to be adopted by system manufacturers for test, repair, maintenance, and field service. These considerations should, in turn, influence the initial design of the system: design for testability (DFT) needs to embrace mechanical as well as electrical considerations. This paper reviews some of the changes that are taking place in the mechanical structure of electronic components and circuits, and discusses how these changes affect test ability. Finally, it describes a new constructional technique (Hierarchical Interconnection Technology¿HIT) which is intended to address some of the problems.
