Method and apparatus for placing and attaching solder balls to substrates

摘要

A method and apparatus for placing and attaching solder balls to a substrate having conductive pads in a predetermined pattern is disclosed. The substrate is placed on a carrier plate. An alignment plate having holes corresponding to the predetermined pattern is mated to the carrier plate with its holes aligned with the predetermine pattern on the substrate. Solder balls are loaded into each hole of the alignment plate. The solder balls may be loaded with a vacuum plate which uses vacuum to pick up solder balls in the predetermined pattern and place them over the holes on the alignment plate. The vacuum is released for dropping the balls in the holes of the alignment plate. Alternatively a shutter plate having holes corresponding to the holes on the alignment plate is fitted on the alignment plate and afforded slidable movement between an offset position and an aligned position. A ball is loaded in each hole in the shutter plate when it is in its offset position. The shutter plate is then slid its aligned position wherein its holes are aligned with the holes on the alignment plate causing the balls to drop into the holes on the alignment plate and onto a conductive pad of the substrate. The assembly of carrier and alignment plate is then heated in a non-oxidizing atmosphere in a furnace causing the solder balls to reflow and attach to the pads on the substrate.