Thermal control mold for making three-dimensional microstructures

A method for fabricating three-dimensional microstructures, the method comprising:

• disposing a substantially planar reflow material on a mold having a molding region, a boundary region, and a thermal-isolating region disposed therebetween, wherein the molding region includes a cavity formed therein and a protrusion projecting upwards from a bottom surface of the cavity and the thermal-isolating region includes at least one pocket formed adjacent to and along a perimeter of the cavity of the molding region, wherein
• a thermal resistance of the thermal-isolating region is proportional to
• R
• 3
• -
• R
• 2
• T
• -
• D
• recess
• ⁢
• ⁢
• 2
• ,
• where R3 is an outer radius of the thermal-isolating region, R2 is an inner radius of thermal-isolating region, T is a thickness of the mold, and Drecess2 is a depth of the at least one pocket of the thermal-isolating region, and
• the mold has a geometrical relationship defined by one or more of [(R3−R2)/(T−Drecess2)], [(R2−R1)/Drecess1], and [(R2−R1)/Drecess2], where R1 is an outer radius of the cavity of the molding region and Drecessl is a depth of the cavity of the molding region;
• heating the reflow material while the reflow material is disposed on the mold, wherein the molding region has a first temperature at or greater than the softening temperature of the reflow material and the boundary region has a second temperature less than the softening temperature of the reflow material and the thermal-isolating region divides thermal masses of the molding region and the boundary region;
• and
• reflowing the reflow material towards the bottom surface of the cavity by creating a pressure gradient across the reflow material, whereby the protrusion extending from the bottom surface of the cavity helps to shape the reflow material and thereby form a three-dimensional microstructure and the reflow material does not flow into the at least one pocket of the thermal-isolating region.

A method for fabricating three-dimensional microstructures, the method comprising:

• disposing a substantially planar reflow material on a mold having a molding region, a boundary region, and a thermal-isolating region disposed therebetween, wherein the molding region includes a cavity formed therein and a protrusion projecting upwards from a bottom surface of the cavity and the thermal-isolating region includes at least one pocket formed adjacent to and along a perimeter of the cavity of the molding region, wherein the at least one pocket of the thermal-isolating region is free from a through-hole extending therefrom, wherein
• a thermal resistance of the thermal-isolating region is proportional to
• R
• ⁢
• ⁢
• 3
• -
• R
• ⁢
• ⁢
• 2
• T
• -
• Drecess
• ⁢
• ⁢
• 2
• ,
• where R3 is an outer radius of the thermal-isolating region, R2 is an inner radius of thermal-isolating region, T is a thickness of the mold, and Drecess2 is a depth of the at least one pocket of the thermal-isolating region, and
• the mold has a geometrical relationship defined by one or more of [(R3−R2)/(T−Drecess2)], [(R2−R1)/Drecess1], and [(R2−R1)/Drecess2], where R1 is an outer radius of the cavity of the molding region and Drecess1 is a depth of the cavity of the molding region, wherein T and Drecess1 are different and wherein T and Drecess2 are different;
• heating the reflow material while the reflow material is disposed on the mold, wherein the molding region has a first temperature higher than a second temperature of the boundary region and the thermal-isolating region divides thermal masses of the molding region and the boundary region;
• and
• reflowing the reflow material towards the bottom surface of the cavity by creating a pressure gradient across the reflow material, whereby the protrusion extending from the bottom surface of the cavity helps to shape the reflow material and thereby form a three-dimensional microstructure.