Phase change material containing fusible particles as thermally conductive filler

1. An electronic assembly comprising:

a microelectronic die;

a heat spreader;

a heat sink; and

first and second thermal interface materials, the first thermal interface material being between the microelectronic die and the heat spreader and the second thermal interface material being between the heat spreader and the heat sink, the first and second thermal interface materials comprising a first and second phase change polymer, respectively, each phase change polymer selected from the group consisting of a polyolefin, an epoxy, a polyester and an acrylic, and the first phase change polymer different from the second phase change polymer, a solder material, said solder material different than said phase change polymer, and a plurality of thermally conductive non-fusible particles, the solder material interconnecting the non-fusible particles to form a plurality of columnar structures within each of the first and second phase change polymers.

2. The electronic assembly of claim 1 , wherein at least one of the first and second thermal interface materials further comprise a non-phase change polymer.

3. The electronic assembly of claim 1 , wherein at least one of the first and second phase change polymers is a liquid above 45° C.

4. The electronic assembly of claim 1 , wherein a non-fusible mesh is placed within at least one of the first and second phase change polymers.

5. The electronic assembly of claim 1 , wherein the non-fusible particles include at least one of glass fiber, graphite fibers, carbon fibers, boron nitride, aluminum oxides, zinc oxide, aluminum, silver, graphite, carbon fibers, diamond, metal coated carbon fiber, and metal coated diamond.

6. The electronic assembly of claim 5 , wherein the non-fusible particles are excluded from the group consisting of lead, cadmium, mercury, antimony and arsenic.

7. A method of constructing an electronic assembly comprising:

interconnecting a microelectronic die and a heat sink with a first thermal interface material, the first thermal interface material comprising a first phase change polymer selected from the group consisting of a polyolefin, an epoxy, a polyester and an acrylic, a solder material different from said first phase change material, and a plurality of thermally conductive non-fusible particles, the solder material interconnecting the non-fusible particles to form a plurality of columnar structures within the first phase change polymer; and

interconnecting a heat spreader and the heat sink with a second thermal interface material, the second thermal interface material comprising a second phase change polymer selected from the group consisting of a polyolefin, an epoxy, a polyester and an acrylic and different from the first phase change polymer, a solder material different from said second phase change material, and a plurality of thermally conductive non-fusible particles, the solder material interconnecting the non-fusible particles to form a plurality of columnar structures within the second phase change polymer.

8. The method of claim 7 , wherein at least one of the first and second thermal interface materials further comprises a non-phase change polymer.

9. The method of claim 7 , wherein at least one of the first and second phase change polymers is a liquid above 45° C.

10. The method of claim 7 , further comprising placing a non-fusible mesh within at least one of the first and second phase change polymers.

11. The method of claim 7 , wherein the non-fusible particles include at least one of glass fiber, graphite fibers, carbon fibers, boron nitride, aluminum oxides, zinc oxide, aluminum, silver, graphite, carbon fibers, diamond, metal coated carbon fiber, and metal coated diamond.

12. The method of claim 11 , wherein the non-fusible particles are excluded from the group consisting of lead, cadmium, mercury, antimony and arsenic.