This problem is likelu a process control problem when the board was manufactured. From your description, I suspect the boards had solder applied first then the plugs. If you LPI first with the pads open and then HASL and then screen print via plugs the HASL process must blow out all via holes, otherwise there may be air trapped between the ink plug and the solder plug. When you heat it up at wave solder the air expands and the solder blows out. Problems can be worse if you plug the vias first and t hen HASL. This creates a dead-end hole with solder at the top and plug ink at the bottom that often traps flux or in the worst case, pre-clean micro etch chemistry. This can blow out at wave solder as you describe or even worse cause long term opens in the plated holes. Your designer can help by either making the vias large enough to blow out more easily at HASL or by not requiring the vias to be plugged. This may require not using metal jacketed components over the vias or using stand-offs to prevent shorting.. On Sat, 14 Sep 1996 23:28:52 +0800 Poh Kong Hui <[log in to unmask]> writes: >Hi, > >Could anyone please tell me why a bare PCB with plugged via-holes, has >solder in the via-hole. ??? > >When I reflow the board, the solder in the via-hole explode out of the >via >hole and fly practically anywhere on the board or somewhere in the >oven. > >The solder has formed a ball and even shorted some area > >Thanks .. Regards. > > >Poh Kong Hui >Nera Electronics >Fax: (65) 7765492 > >*************************************************************************** >* 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. > * >*************************************************************************** > > *************************************************************************** * 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. * ***************************************************************************