An Approach for Evaluating Polymer Materials as Protective Coatings on Hybrid Microcircuits

Results are discussed of an evaluation program for polymer materials considered for applications as protective coatings on hybrid microcircuits. The general organization of the program was in terms of seven potential mechanisms by which coatings could fail to provide protection. Emphasis is on describing those six tests which developed differences in material behavior considered to be significant in terms of the general application. Three involved electrical performance of the films alone or in conjunction with hybrid circuit elements, two dealt with mechanical properties, and one with chemically related behavior. It is suggested that the tests could be used in selecting promising candidates for particular applications which relate to the test conditions or in understanding some failure modes which could be expected in complex hybrid microcircuit assemblies. A brief review is given of those tests which were not considered to develop distinctions between materials. As a point of exception, the role of organic coatings on bare semiconductor device surfaces was not investigated.