We are trying to determine the amount of cleaning necessary, if necessary, prior to conformal coating with HumiSeal 1A20. We currently use water soluable flux in our wave soldering machine. We clean with water, no additivites, in a Trieber SMT type machine. Additional components may be added, after cleaning, using a no clean flux core solder. A residue is left on the boards with this type flux. The question are: 1. Should secondary cleaning be accomplished prior to conformal coating? 2. What should be used for the second cleaning? This is asked with regards to using materials without CFC and/or requiring special equipment? 3. How clean is clean for adhesion ot the conformal coating material, HumiSeal 1A20 or 1A27. Any input regarding the above questions will be appriciated. Richard E. Ackerson Sr. Industrial Engineer Elsag Bailey Process Automation Phone 216-585-7646 Fax 216-585-8867 Interne [log in to unmask]