THE APPLICATION OF NUCLEAR TECHNIQUES TO THE MANUFACTURE OF HIGH-RELIABILITY PRINTED CIRCUIT BOARDS

摘要

Certain process solution leave undesirable residues in the manu-facture of printed circuit boards that are below the level of detectability by conventional analytical techniques. The purpose of this investigation was to test the effects of some of these residues on circuit board relia¬bility by radiotracer techniques and further show that these techniques could be used routinely on a production line.nIn this study, the use of radioactive tracers has been shown to be a Hd technique for determination of the amounts of residual process con-tamination. Health and safety problems related to the use of such figures demonstrated to be minimal.nBy use of the radioisotope tracing technique, it has been shown that process contamination from resist paint and ferric chloride etch, employed in circuit board manufacture at or near normal manufacturing levels, causes an increase in solder joint defects. This degradation of solder joint relia¬bility can be detected and controlled by production-line use of radiotracers.nThe corrosion potential of boards fluxed with radioisotope tagged flux can be determined by an integrated count rate of the entire board surface. This investigation suggests that this method is the only noh-destructive technique available for assuring the minimum corrosion potential of all boards manufactured. This method will also test all the individual circuit boards and gives results immediately, releasing the circuit board to production.