This part of IEC 61189 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 are used for the evaluation. Coupons are conditioned and measurements taken at a high temperature and humidity. The electrodes are electrically biased during conditioning to facilitate electrochemical reactions, as shown in Figure 1 and Figure 3.
Reference can be made to IEC TR 61189-5-506, which examines different geometry comb patterns: 400 µm x 500 µm; 400 µm x 200 µm; and 318 µm x 318 µm.
