Abstract: An apparatus and test method for determining the cleanliness (based on corrosivity) of a specific area on an electronic circuit assembly, such as the area between holes or pads on a single side of an assembly. The apparatus includes: (1) an extraction cell for providing an extraction fluid to an electronic circuit assembly ("ECA") area to be measured; (2) an extraction fluid for extracting residue from the ECA area to be measured; (3) a test cell with two or more electrodes and a voltage source for providing a voltage to the electrodes; and (4) a timer for measuring the time between the application of the voltage and an electrical short between the electrodes.