Dip formation of flip-chip solder bumps
AssigneeCorning Incorporated
InventorsAlain R. Carre, Jurriaan Gerretsen
Life of this patent
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Abstract
A process for fabricating a solder bump (113) includes providing an inorganic de-wetting substrate (102). In order to form a composite substrate (20), having the desired wetting/dewetting composition, a wetting metal is first applied on the inorganic de-wetting substrate to create at least one wetting metal pad (52). The composite substrate (20) is then dipped or otherwise immersed into a reservoir of liquid solder (106). Next, the composite substrate (20) is redrawn (116), or otherwise removed, from the liquid solder to form solder bumps (113) on the at least one metal wetting pad (52).
Claims20
A process for fabricating a solder bump having a desired shape profile, the process comprising the steps of:
- selecting a liquid solder having a capillary length;
- providing an inorganic de-wetting substrate;
- applying a wetting metal to create a plurality of wetting metal pads on the inorganic de-wetting substrate to form a composite substrate having a composite surface of the plurality of wetting metal pads surrounded by a de-wetting background, wherein each wetting metal pad has a dimension smaller than the capillary length;
- containing a reservoir of the liquid solder having a horizontal top flat surface of the liquid solder;
- vertically dipping the composite substrate into the reservoir of liquid solder for wetting the liquid solder onto the composite substrate such that the composite surface perpendicularly immerses pass the horizontal top flat surface of the liquid solder;
- and
- vertically removing the composite substrate from the liquid solder such that the composite surface is perpendicularly withdrawn pass the horizontal top flat surface of the liquid solder for the liquid solder to remain only on the plurality of wetting metal pads as a solder drop having the desired shape profile and not adhere to the de-wetting background to form a remaining plurality of corresponding solder bumps having the desired shape profile to provide a sufficient bearing effect on the plurality of wetting metal pads.
A process for fabricating a solder bump having a desired shape profile, the process comprising the steps of:
- selecting a liquid solder having a capillary length;
- providing a substrate comprising a wetting pad on a de-wetting background on a composite surface of the substrate, the wetting pad having a dimension smaller than the capillary length;
- vertically dipping the substrate into the liquid solder such that the composite surface perpendicularly immerses pass a horizontal top flat surface of the liquid solder;
- and
- vertically redrawing the substrate from the horizontal top flat surface of the liquid solder such that the composite surface is perpendicularly withdrawn pass the horizontal top flat surface of the liquid solder for the liquid solder to remain only on the wetting pad as a solder drop having the desired shape profile and not adhere to the de-wetting background to form a resultant solder bump having the desired shape profile to provide a sufficient bearing effect.
A method for fabricating a solder bump having a desired shape profile for passive height alignment, the method comprising the steps of:
- selecting a liquid solder having a capillary length;
- providing a substrate comprising a gold wetting pad on a silica or silica-based glass de-wetting background on a composite surface of the substrate, the gold wetting pad having a dimension smaller than the capillary length of the liquid solder;
- and
- vertically dipping the substrate into a liquid solder, wherein the composite surface is perpendicularly immersed pass a horizontal top flat surface of the liquid solder and redrawn in an opposite direction such that the composite surface perpendicularly protrudes from the horizontal top flat surface of the liquid solder for the liquid solder to remain only on the wetting pad as a solder drop having the desired shape profile, wherein the solder drop has a contact angle greater than ninety degrees with respect to the de-wetting background and not adhere to the de-wetting background to form a resultant solder bump with a sufficient bearing effect and the desired shape profile for passive height alignment.
Dependencies are inferred from the claim text.