IPC TP-1113

Abstract

<strong><u>Introduction</u></strong> <br>In the early 1970's the only fluxes permissible for electronics manufacturing for military applications were types R (pure rosin only) and RMA (rosin based, mildly activated). Before any of these fluxes could be approved and established on the military "qualified products list", it was necessary to demonstrate that were non-corrosive and did not contain ionic halides in of established critical levels. All fluxes were required to pass a silver chromate paper test which sensitively indicates presence of halide ions. <br>Additionally, the flux was subjected a copper mirror corrosion test which is a sensitive indicator any corrosive behavior of the flux toward copper. <br>Because of the desirability for using stronger, more active fluxes in electronic assembly, the military agencies decided to include the category RA (fully activated rosin) on their approved flux list. RA fluxes do not, as a rule, pass the copper mirror or chromate paper tests and there was, therefore, increased concern about allowing the more highly active rosin flux into military electronics manufacture. <br>Although circuit assemblies are ordinarily cleaned after assembly soldering, traces of RA fluxes, left after the final cleaning, would be considered a greater risk than those of RMA or R types. It was, therefore, imperative to thoroughly clean these assemblies to provide assurance that the potentially harmful active residues had been thoroughly removed.