As one response to Technet has already said the key is checking the compatibility of the cleaning solution with the preferred paste. The paste supplier should be able to define the best cleaning solution for the removal of wash offs and reflowed board if you need to clean them at any time. You can buy a cleaning system and the machine will mechanically remove any trace of balls and residues but that is not cleaning. You need to first define the process which will allow the residue to go into solution with the cleaner in the shortest time possible. Manual hand cleaning only make it difficult for the chosen machine to get the metallic particles out of the holes, via holes and resist windows. The paste manufacturer then normally is blamed for causing solder balls after reflow when they were there before the process started. Bob Willis Process Engineering Consultant Electronic Presentation Services 2 Fourth Avenue, Chelmsford, Essex CM1 4HA. England. Tel: (44) 01245 351502 Fax: (44) 01245 496123 Home Page: http://ourworld.compuserve.com/homepages/Bwillis Email: [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************