Electronic package with varying interconnects

An interconnect layer for an electronic device comprising:

• a plurality of solder bumps arranged with a uniform pitch, wherein:
• a first subset of the plurality of solder bumps comprises solder bumps each having a first cross-sectional area, and wherein the first subset is arranged along a first position at a first edge of the interconnect layer,
• a second subset of the plurality of solder bumps comprises one or more solder bumps each having a second cross-sectional area, and wherein the second subset is arranged at a second position of the interconnect layer, and
• the plurality of solder bumps have a plurality of cross-sectional areas, wherein individual cross-sectional areas decrease along an underfill flow direction from the first position to the second position, the plurality of cross-sectional areas causing underfill material, when dispensed into the interconnect layer at the first edge, to flow by capillary action in the underfill flow direction,
• wherein at least one of the plurality of solder bumps arranged between the first subset and the second subset has a third cross-sectional area that is less than the first cross-sectional area and greater than the second cross-sectional area, and
• wherein the cross-sectional areas of the plurality of solder bumps monotonically decrease along the underfill flow direction.

A method comprising:

• during a first plating process, forming a first plurality of C4 pillars on a first structure, wherein the first plurality of C4 pillars comprise a plurality of cross-sectional areas, wherein within the plurality of cross-sectional areas, individual cross-sectional areas monotonically decrease along an underfill flow direction between a first subset of the first plurality of C4 pillars to a second subset of the first plurality of C4 pillars, the plurality of cross-sectional areas comprising a first cross-sectional area of the first subset, a second cross-sectional area of the second subset, and at least one intermediate cross-sectional area;
• during a second plating process, forming a plurality of solder plates on the C4 pillars, wherein each solder plate of the plurality of solder plates comprises a mass of solder corresponding to a cross-sectional area of a respective C4 pillar on which the solder plate is formed, wherein the mass of solder provides for a consistent interconnect height upon solder reflow;
• and
• during a finishing process, forming a plurality of solder bump interconnects between the first plurality of C4 pillars on the first structure and a plurality of contacts on a second structure, the plurality of solder bump interconnects having a uniform pitch, the plurality of cross-sectional areas causing underfill material, when dispensed between the first structure and the second structure, to flow by capillary action in the underfill flow direction.