Method of bumping substrates by contained paste deposition
AssigneeHewlett-Packard Company
InventorsMatthew K. Schwiebert, Donald T. Campbell, Matthew Heydinger, Robert E. Kraft, Hubert A. Vander Plas
Life of this patent
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Abstract
A solder bump is stenciled into a substrate, providing bumped substrate at pitches below 400 microns. The solder is applied through stencil/mask and paste method; the mask, however, remains attached to the substrate during reflow. Pitches of greater than 400 microns may also be obtained through the invention. The invention further provides for generation of uniform, controllable volume metal balls
Claims29
A method for forming solder bumps directly on a substrate having a plurality of wettable pads comprising the steps of:
- positioning a non-wettable metal mask on the substrate such that a plurality of apertures in the mask align with the pads;
- applying solder paste to the metal mask such that the solder paste loads the mask apertures;
- reflowing the solder paste to form solder bumps on the pads;
- and
- removing the metal mask after formation of the solder bumps.
A method for electrically connecting a first substrate having a plurality of wettable pads to a second substrate having a plurality of wettable pads comprising the steps of:
- forming solder bumps on the first substrate by a method comprising the steps of:
- attaching a non-wettable metal stencil mask having a plurality of apertures on the substrate such that the mask apertures are in alignment with the pads;
- applying solder paste to the metal mask such that the solder paste loads the mask apertures;
- reflowing the solder paste to form solder bumps on the pads;
- and
- removing the metal mask after forming the solder bumps;
- positioning the solder bumps formed on the first substrate in registry with the wettable pads of the second substrate;
- and
- reflowing the solder bumps to form an electrical connection between the first substrate and the second substrate.
Dependencies are inferred from the claim text.