Indium-based interface structures, apparatus, and methods for forming the same

1. A method, comprising forming a solid indium-based interface between a first surface and a second surface by:

first positioning a first side of an indium-based material in contact with the first surface while heating the indium-based material above the melting point of the indium-based material, and forming at least one bump on an opposing second side of the indium-based material, the bump having an outer surface that extends outward and away from the second side of the indium-based material;

then maintaining the indium-based material in contact with the first surface while allowing the indium-based material to cool below the melting point of the indium-based material;

then positioning the outer surface of the bump in contact with the second surface while again heating the indium-based material above the melting point of the indium-based material to melt the bump into a raised contact having an outer surface that extends outward and away from the second side of the indium-based material in contact with the second surface; and

then maintaining the second surface in contact with the outer surface of the raised contact while allowing the indium-based material to cool below the melting point of the indium-based material to form a solid indium-based interface that is mechanically adhered without the presence of solder to the first surface and to the second surface with a height of the raised contact forming a gap between the second surface and the second side of the indium-based material.

2. The method of claim 1 , where the first surface comprises a heat sink; and where the second surface comprises an external surface of at least one heat-emitting component.

3. The method of claim 1 , where the step of forming at least one bump on an opposing second side of the indium-based material further comprises;

positioning the second side of the indium-based material in contact with a mandrel surface that has at least one opening defined therein while the first side of the indium-based material is positioned in contact with the first surface and while heating the indium-based material above the melting point of the indium-based material to cause the indium material to flow into the mandrel opening to form the bump on the second side of the indium-based material;

then maintaining the second side of the indium-based material in contact with the mandrel surface while allowing the indium-based material to cool below the melting point of the indium-based material to solidify the bump on the second side of the indium-based material; and

then separating the mandrel surface from contact with the second side of the indium-based material while the first side of the indium-based material remains in contact with the first surface.

4. The method of claim 3 , where the first surface comprises a heat sink; where the second surface comprises separate external surfaces of multiple electronic components that are mounted to a substrate at given locations; where the step of forming at least one bump on the opposing second side of the indium-based material further comprises forming multiple bumps disposed on the opposing second side of the indium-based material at mating locations to the given locations of the multiple electronic components; and where the method further comprises:

then positioning the outer surfaces of the multiple bumps in contact with corresponding external surfaces of the multiple electronic components while again heating the indium-based material above the melting point of the indium-based material to melt each of the bumps into a raised contact having an outer surface that extends outward and away from the second side of the indium-based material in contact with at least one corresponding external surface of one of the electronic components; and

then maintaining the outer surfaces of the multiple raised contacts in contact with corresponding external surfaces of the multiple electronic components while allowing the indium-based material to cool below the melting point of the indium-based material to form a solid indium-based thermal interface material (TIM) adhered to and thermally coupled between the heat sink and the multiple electronic components with a height of the raised contacts forming a first gap between the external surfaces of the multiple electronic components and the second side of the indium-based material, and with a second gap formed between the substrate and the second side of the indium-based material.

5. The method of claim 4 , where the melting point of the indium-based material is from greater than or equal to 125° C. to less than 230° C.

6. The method of claim 4 , further comprising applying a compressive force of from 1 psi to 10 psi between the indium-based material and each of the first surface and the second surfaces while heating the indium-based material above the melting point of the indium-based material and allowing the indium-based material to cool below the melting point of the indium-based material to form a solid indium-based interface; and releasing the compressive force after the indium-based material has cooled below the melting point of the indium-based material to form the solid indium-based thermal interface material (TIM) to have an effective bulk linear thermal conductivity of from 16 W/m-K to 86 W/m-K in the absence of applied compressive force between the indium-based material and each of the first surface and the second surfaces.

7. The method of claim 1 , where the indium-based material is indium.

8. A method, comprising forming a solid indium-based interface between a first surface and a second surface by:

first positioning a first side of an indium-based material in contact with the first surface while heating the indium-based material above the melting point of the indium-based material, and forming at least one bump on an opposing second side of the indium-based material, the bump having an outer surface that extends outward and away from the second side of the indium-based material;

then maintaining the indium-based material in contact with the first surface while allowing the indium-based material to cool below the melting point of the indium-based material;

then positioning the outer surface of the bump in contact with the second surface while again heating the indium-based material above the melting point of the indium-based material to melt the bump into a raised contact having an outer surface that extends outward and away from the second side of the indium-based material in contact with the second surface; and

then maintaining the second surface in contact with the outer surface of the raised contact while allowing the indium-based material to cool below the melting point of the indium-based material to form a solid indium-based interface that is mechanically adhered without the presence of solder, adhesive, or chemical bonding to the first surface and to the second surface with a height of the raised contact forming a gap between the second surface and the second side of the indium-based material.