Integrated circuit heat spreader including sealant interface material

An integrated circuit (IC) die package, comprising:

• a package substrate;
• an IC die coupled to a first region of the package substrate;
• a heat spreader over the IC die, wherein the heat spreader comprises:
• a top sheet having an interior surface area that is over the IC die, the top sheet comprising a metal surface finish covering an underlying material;
• and
• an interface material on a periphery of the top sheet, wherein the interface material substantially encloses the interior surface area and is absent from the interior surface area, wherein the interface material has a different composition than the surface finish, wherein a surface roughness is greater for the interface material than the for surface finish, and wherein the interface material has a surface roughness profile with peaks and valleys varying between a minimum surface profile valley and a maximum surface profile peak that differ by at least 10 μm in a direction normal to a plane of the top sheet;
• and
• an adhesive sealant in contact with the interface material and in contact with a second region of the package substrate that substantially surrounds the first region.