Forming solder balls on substrates
OwnerJohn Mackay, Tom Molinaroinventors
Life of this patent
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Abstract
A mask (stencil) having cells (openings) is disposed on a surface of a heater stage, and is then filled (printed) with solder paste. Then a substrate is assembled to the opposite side of the mask. Then the solder paste is reflowed. This may be done partially inverted. Then the mask is separated from the substrate, either before or after cooling. Solder balls are thus formed on the substrate, which may be a semiconductor wafer. A biased chuck urges the substrate into intimate contact with the mask. A method for printing the mask with solder paste is described. Methods of forming high aspect ratio solder bumps (including balls and reflowable interconnect structures) are described.
Claims7
Apparatus for forming solder balls on substrates comprising a chuck assembly, said chuck assembly comprising:
- a rigid, generally planar chuck base having a cavity extending into the chuck base from a top surface thereof;
- a generally planar, flexible diaphragm extending across the cavity and secured to the chuck base;
- said cavity being sized and shaped to receive the diaphragm;
- further comprising:
- a generally planar, flexible manifold element;
- a recess, coaxial with and larger than the cavity, extending into the chuck base from the top surface thereof, said recess being sized and shaped to receive the manifold element;
- further comprising:
- a permeable substrate disposed beneath the diaphragm, between the diaphragm and a bottom surface of the cavity;
- wherein the permeable substrate comprises a powdered metal plate.
Dependencies are inferred from the claim text.