This part of IEC 61189-5 is used to quantify the deleterious effects of flux residues on surface insulation resistance (SIR) in the presence of moisture. Interdigitated comb patterns comprising long parallel electrodes on an IPC B53 standardized test coupon shall be used for the evaluation. Coupons shall be conditioned and measurements taken at a high temperature and humidity. The electrodes are electrically biased during conditioning to facilitate electrochemical reactions, see Figure 1 and Figure 3. Reference should be made to IEC TR 61189-5-506 that examined different geometry comb patterns: 400¼m x 500¼m; 400¼m x 200¼m; and 318¼m x 318¼m. Specifically, this method is designed to simultaneously assess: " Leakage current caused by ionized water films and electrochemical degradation of test vehicle, (corrosion, dendritic growth). " Provide metrics that can appropriately be used for binary classification (e.g. go/no go; pass/fail) " Compare, rank or characterize materials and processes. This test is carried out at high humidity and heat conditions.