Heat-dissipating composition, heat-dissipating member, and filler aggregate for heat-dissipating member
The heat-dissipating composition according to the present invention comprises a polymer matrix and diamond particles. The present invention provides the heat-dissipating composition compatibly satisfying both electric insulativity and heat dissipativity.
1. A heat-dissipating composition comprising a polymer matrix and thermally conductive fillers, the polymer matrix comprising silicone resin, silicone oil or epoxy resin, the thermally conductive fillers comprising diamond particles, and the composition having a void fraction of 2% or lower,
wherein the diamond particles have an average particle diameter of 0.5 μm or larger, and
wherein the diamond particles have a surface oxygen content of 10% or larger,
wherein the surface oxygen content is an intensity ratio of oxygen obtained by measuring the diamond particles by XPS analysis to determine a surface element ratio.
2. The heat-dissipating composition according to claim 1 , wherein the void fraction is obtained by calculating (1−Dr/Di)×100 where Dr represents a real density of the heat-dissipating composition, and Di represents an ideal density of the heat-dissipating composition, the ideal density calculated from the density of each component and the mixing ratio, and on the assumption of no voids.
3. The heat-dissipating composition according to claim 1 , wherein a gradient (ΔW/ΔD) of change in a thermal resistance value with respect to change in a thickness is 1.8 or lower,
wherein the gradient (AW/AD) is a value obtained by calculating the expression of ΔW K·cm 2 /W/ΔD mm=(W2−W1)/(D2−D1),
wherein W1 and W2 are respective thermal resistance values measured in the thickness direction in a case where the heat-dissipating composition is made to be ones having different thicknesses D1 and D2, respectively.
4. The heat-dissipating composition according to claim 1 , wherein the diamond particles are surface-treated with a silane compound.
5. The heat-dissipating composition according to claim 1 , wherein the polymer matrix comprises silicone resin or silicone oil, and the diamond particles are surface-treated with a silane compound.
6. The heat-dissipating composition according to claim 1 , wherein the polymer matrix comprises epoxy resin.
7. The heat-dissipating composition according to claim 1 , wherein the diamond particles have a spheroidicity of 0.5 or higher, and the spheroidicity of each filler is determined as an average value of the following calculation by examining an electron microscope photograph: for each of 300 particles in an acquired image, a diameter of a circle whose area is equivalent to a projected area of a particle/a diameter of the smallest circle circumscribing an projected image of the particle is calculated.
8. The heat-dissipating composition according to claim 1 , wherein a volume of the diamond particles is 15% or higher with respect to a total volume of the heat-dissipating composition.
9. The heat-dissipating composition according to claim 1 , comprising other thermally conductive fillers other than the diamond particles.
10. The heat-dissipating composition according to claim 9 , wherein the other thermally conductive fillers have an average particle diameter of 0.1 μm or larger and 200 μm or smaller.
11. The heat-dissipating composition according to claim 1 , wherein a total volume of the thermally conductive fillers is 40% or higher and 92% or lower with respect to a total volume of the heat-dissipating composition.
12. The heat-dissipating composition according to claim 1 , comprising, as thermally conductive fillers, diamond particles, or both of diamond particles and other thermally conductive fillers other than the diamond particles,
wherein the thermally conductive fillers have a first diamond population of diamond particles having an average particle diameter of 10 μm or larger and 200 μm or smaller and a second diamond population of diamond particles having an average particle diameter of 0.1 μm or larger and 10 μm or smaller, wherein a volume ratio of the first diamond population to the second diamond population is 0.2 to 5.
13. The heat-dissipating composition according to claim 1 , wherein the polymer matrix has a contact angle to the thermally conductive fillers comprising the diamond particles of 70° or smaller.
14. The heat-dissipating composition according to claim 1 , wherein the diamond particles are diamond particles synthesized by being crystallized at a high temperature and under high pressure in the presence of a metal catalyst.
15. The heat-dissipating composition according to claim 1 , wherein the heat-dissipating composition is in a form of paste.
16. The heat-dissipating composition according to claim 1 , wherein the thermally conductive fillers comprise a diamond having an average particle diameter of 10 μm or larger and 200 μm or smaller and a globular filler having an average particle diameter of 0.1 μm or larger and smaller than 10 μm.
17. A heat-dissipating member, being formed of a heat-dissipating composition according to claim 1 .
18. An electronic device comprising an electronic component and the heat-dissipating member according to claim 17 arranged on the electronic component.