Method and apparatus for placing and attaching solder balls to substrates
First Claim
1. A method for attaching solder balls to a substrate in a predetermined pattern defined on the substrate comprising the steps of:
- providing an alignment plate comprising a plurality of through-holes in a pattern which corresponds to the predetermined pattern, said through-holes having a diameter slightly larger than the diameter of the solder balls;
placing the alignment plate over the substrate so that the through-holes of the alignment plate are aligned with the predetermined pattern on the substrate;
loading a solder ball into each hole of the alignment plate whereby each solder ball falls into contact at a location defining the predetermined pattern on the substrate;
heating the solder balls in a vacuum to a temperature sufficient to reduce oxides;
heating the solder balls in an inert atmosphere to a temperature sufficient to melt the solder balls; and
cooling the melted solder balls sufficiently to resolidify the solder balls which bond to the substrate.
2 Assignments
0 Petitions
Accused Products
Abstract
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.
47 Citations
23 Claims
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1. A method for attaching solder balls to a substrate in a predetermined pattern defined on the substrate comprising the steps of:
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providing an alignment plate comprising a plurality of through-holes in a pattern which corresponds to the predetermined pattern, said through-holes having a diameter slightly larger than the diameter of the solder balls; placing the alignment plate over the substrate so that the through-holes of the alignment plate are aligned with the predetermined pattern on the substrate; loading a solder ball into each hole of the alignment plate whereby each solder ball falls into contact at a location defining the predetermined pattern on the substrate; heating the solder balls in a vacuum to a temperature sufficient to reduce oxides; heating the solder balls in an inert atmosphere to a temperature sufficient to melt the solder balls; and cooling the melted solder balls sufficiently to resolidify the solder balls which bond to the substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification