Mark If your SMD's are desoldering you are going over the melting point of the solder. Well that's trivial I know. The question is, where in the soldering operation you pump enough energy into the board in order to increase this temperature. This can only be answered, if you measure the temperature- time behaviour of the boards during soldering. I assume that passing faster through the waves could ease the problem. Another approach I've seen is installing a van that blows cool air on the top side of the board. ( Nice job for a lab. technician). But without seeing the Temp.-time profile and the solder machine it's quite difficult to give a sophisticated advise. Blowholes are almost certain caused by pinholes in the plating of the trough holes. These pinholes are usually caused by glass fibres reaching out the drilled walls if the drills are pressed too fast through the PCB or if they are used too long. Whether there are any fibres can be seen with mircrosections where you see whether the surface of the walls of the holes was excessively rough before plating. Another reason is the plating process where the first plating ( don't know the correct expression in English ) is too thin, thus leaving free glass fibres uncovered. This again can be see in microsection. Be only sure the the sections are not just set in the directions on the glass fibres but also 45° to this direction. Best regards Guenter Grossmann *************************************************************************** * 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. * ***************************************************************************