sam mccorkel wrote:- >We're having trouble with boards that have large ground plane areas. The >solder isn't as flat as we need it to be and it puddles around the large >holes. We'd like to know if anyone out there has advise on what to adjust or >if a different process is recommended. Hi Sam, Just a few thoughts. Maybe the air knives are in need of replacement. If the slots are enlarged this can have a dramatic effect on the amount of solder remaining. I expect you have tried the obvious of increasing dwell time, slowing down the withdrawal speed, and increasing air pressure. Another factor is the movement of solder in the pot. Make sure the pump is working to prevent cold spots forming when the panel is inserted. You could try double cycling to get a better result. The first cycle can be considered the pre-heat. Failing that. If there is a large ground plane, can it be covered with solder mask or can thermal breaks be put around the holes. Is reflow an option instead of hot air level. We have one particular heavy backplane which is totally 2oz copper on the outside with many large holes and do not have a problem with flatness or solder thickness in holes so it is possible to do. Our machine is a vertical Quicksilver. Good luck. Paul Gould Teknacron Circuits Ltd [log in to unmask] Isle of Wight,UK ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################