4. Conclusions
The present study aims to provide a thermal interface material with
aligned graphite nanofibers in the thermal interface material to enhance
the thermal interface material performance. The effect of filler volume
fraction on the thermal resistivity of the thermal contact and the
thermal conductivity of the thermal interface material is investigated
for graphite platelets and carbon black. The effect of pressure on the
bond line thickness of the thermal interface material is evaluated for
smooth and rough surfaces. Particular emphasis is placed upon the heat
conduction properties of thermally conductive interface materials with
exfoliated graphite platelets. The major conclusions are summarized as
follows:
- Polymeric elastomer materials offer both high thermal performance and
reasonable gap filling capability to enable good contact between a
semiconductor component and a heat sink.
- Under mechanical pressure, the soft thermal interface material
conforms to the microscopic surface contours of the adjacent solid
surfaces and increases the microscopic area of contact between the
thermal solution surface and the silicon die surface and therefore
reduces the temperature drop across this contact.
- The heat dissipating component should advantageously be relatively
anisotropic, as compared to a metal like copper or aluminum and
exhibit a relatively high ratio of thermal conductivity to weight.
- Thermal interface materials provide a limited heat-conduction path and
may include flexible heat-spreading materials and one or more layers
of soft thermal interface material.
- Reducing the strain on the thermal interface material may reduce the
potential for pump-out and the associated increase in thermal
resistance due to loss of material from the interface.
- Thermal conductivity is driven primarily by the nature of the filler,
which is randomly and homogeneously distributed throughout the organic
matrix.
- Pump-out of the thermal interface material results in increased
thermal resistance due to loss of material from the interface.
- The thermal interface material can migrate out of the interface volume
between the thermal conducting members and onto the power input pads,
resulting in excessive heating and part failure at the power
interconnect.