Interrupting the tests and removing the specimen in the middle of the series caused a slight increase in current leakage. These changes might be due to the wettability of the surface of the substrate board. We can also report that migration is not as likely to occur when using organic acid flux in the dew cycle test. Our theory is that when organic material exists between water and the surface of the substrate board, there is less bonding strength between water molecules and the surface of the substrate board, causing lower wettability. Changes in leakage current are thought to be related to the moisture absorption of the substrate board, but that does not seem to contribute very much to leakage.
Leakage seems to be caused mainly by the wettability of the substrate board.
In general, measuring insulation resistance between conductors is not adequate for evaluating the amount of ion migration. Because leakage is severe when dew condensation is on the substrate board, you can only measure the insulation resistance when the dew condensation has evaporated. It is crucial, therefore, to observe the growth of migration, especially up to the point that insulation resistance deteriorates. To make this observation, this specimen must be removed from the chamber during the test. Finally, we need to continue to study how dew condensation affects conditions in the dew cycle test chamber.