andre, solder balls could be a result of incorrect placement of components by the placement machine. Also depending upon what placement equipment you are using, also check to see how far the nozzle is comming down to place the component. I am assuming you are checking your printing registration, when the board is processed through the printer. A good check would be to to inpsect board after printing, and then after placement. Also, where are you finding the solder balls? Is it along a particular area on the board or at random places. If you are finding them at random places,and you have done the inspection before the reflow oven, you might be introducing the board and paste to initial high soak temp's which is causing the moisture in the solder paste to boil and explode. What is your processing window between the processes? How long does a board sit in the environment before it is reflowed? If the solder balls are at a specific location at all times then it may be a design issue. Have you checked your paste? Some paste vendors, due to out of control processes might produce pastes with very fine solder balls , which lend towards solder balls? Thanks Nasir ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################