Surface insulation resistance testing of solder pastes with protective coating

This paper presents the results obtained after performing SIR testing in order to evaluate different solder materials. The scope of the test was to determine the effects of the reflow process used and of a protective coating on surface insulation resistance (SIR) in the presence of medium heat and high humidity for several solder pastes. There were used special designed test pattern boards according to IPC-B-24 and several solder pastes with no-clean fluxes: SAC305, OM338PT, OM5300, SN100C and SN100C-XF3. After 110 hours, the measurements showed the reduced values of the average surface insulation resistance. The optical inspection did not show any electrochemical formation (dendrites) between conductors.