Stencil design for solder paste printing

A stencil for stencil printing of metal onto a semiconductor wafer for semiconductor wafer bumping comprising:

• a substrate having a hole defined therein substantially shaped to correspond to and receptive to the semiconductor wafer as a whole;
• and,
• an interior edge of the substrate surrounding the hole and having a rectangular in cross-profile shape upper lip under and directly against which outer-most edges of the semiconductor wafer are adapted to be positioned without a gap therebetween,
• wherein the upper lip of the interior edge of the substrate surrounding the hole substantially prevents the solder from flowing onto the outer-most edges and a bottom of the semiconductor wafer during stencil printing of the solder.

A stencil for stencil printing of metal onto a semiconductor wafer for semiconductor wafer bumping comprising:

• a substrate having a hole defined therein substantially shaped to correspond to and receptive to the semiconductor wafer as a whole;
• and,
• an interior edge of the substrate surrounding the hole and having a triangular in cross-profile shape upper lip under and directly against which outer-most edges of the semiconductor wafer is are adapted to be positioned without a gap therebetween,
• wherein the upper lip of the interior edge of the substrate surrounding the hole substantially prevents the solder from flowing onto the outer-most edges and a bottom of the semiconductor wafer during stencil printing of the solder.