This part of IEC 61189 is used for evaluating the changes to the surface insulation resistance of a pre-selected material set on a representative test coupon and quantifies the deleterious effects of improperly used materials and processes that can lead to decreases in electrical resistance. An assembly process involves a number of different process materials including solder flux, solder paste, solder wire, underfill materials, adhesives, staking compounds, temporary masking materials, cleaning solvents, conformal coatings and more. The test employs two different test conditions of 85 °C and 85 % relative humidity (RH), preferred for a process that includes cleaning, or 40 °C and 90 % relative humidity (RH), preferred for processes where no cleaning is involved. NOTE 40 °C and 93 % RH can be used as an alternative to 40 °C and 90 % RH. Additional information is provided in 5.4 and A.5.2. Testing is material (set) and process / equipment specific. Qualifications are to be performed using the production intent equipment, processes and materials.
