Flip chip with integrated mask and underfill
OwnerKenneth Burton Gilleoinventor
Life of this patent
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Abstract
A flip chip having solder bumps, an integrated underfill, and a separate flux coating, as well as methods for making such a device, is described. The device is characterized in that the underfill material is provided on the chip surface prior to the application of solder bumps, and then treated to form apertures therein which act as a mask for solder bump application. The resulting device is well suited for a simple one-step application to a printed circuit board, thereby simplifying flip chip manufacturing processes which heretofore have required a separate underfilling step.
Claims17
An integrated circuit assembly which comprises:
- a) a substrate having at least one solderable contact site on a surface thereof;
- and
- b) an underfill material applied to the surface of the substrate, the underfill material substantially entirely covering the surface of the substrate having the solderable contact site.
An integrated circuit assembly which comprises:
- a) a substrate having at least one solderable contact site on a surface thereof-, and b) an underfill material applied to the surface of the substrate, the underfill material substantially entirely covering the surface of the substrate having the solderable contact site except at the solderable contact site itself, thereby allowing the underfill to act as a mask exposing substantially only the solderable contact site on the substrate surface.
A method of making an integrated circuit assembly which comprises the steps of:
- a) providing a substrate having at least one solderable contact site on a surface thereof-, b) applying an underfill material to the substrate surface in a manner which substantially entirely covers the substrate surface and the solderable contact site;
- c) treating the underfill material to form at least one aperture therein, the at least one aperture extending substantially entirely through the underfill material and being located such that it exposes only the solderable contact site;
- d) applying at least one solder bump to the assembly in a manner such that a bump occupies each aperture in the underfill, contacts the exposed solderable contact site therein, and extends above the underfill material;
- and
- e) applying a flux to the surface, the flux covering at least the exposed portions of the solder bumps.
A method for affixing an integrated circuit chip to a substrate which comprises the steps of:
- a) providing a substrate having a plurality of solderable contact sites on a surface thereof;
- b) providing an integrated circuit chip having a plurality of solderable contact sites on a surface thereof, each solderable contact site on the integrated circuit chip having a corresponding solderable contact site on the surface of the printed circuit board, the integrated circuit chip further characterized in that it was made by a process including the steps of:
- i) providing a semiconductor wafer having at least one solderable contact site on a surface thereof;
- ii) applying an underfill material to the wafer surface in a manner which substantially entirely covers the wafer surface and the solderable contact site;
- iii) treating the underfill material to form at least one aperture therein, the at least one aperture extending substantially entirely through the underfill material and being located such that it exposes only the solderable contact site on the wafer;
- iv) applying at least one solder bump to the assembly in a manner such that a bump occupies each aperture in the underfill, contacts the exposed solderable contact site therein, and extends above the underfill material;
- v) applying a flux to the surface, the flux covering at least the exposed portions of the solder bumps;
- and
- vi) dividing the wafer into at least one integrated circuit chip;
- c) positioning the integrated circuit chip relative to the printed circuit board such that each solder bump is in contact with a solderable contact site on the printed circuit board;
- d) heating the integrated circuit chip to a temperature sufficiently high to melt the solder and the underfill material;
- and
- e) allowing the solder and underfill material to solidify.
Dependencies are inferred from the claim text.