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1.
The use of 0.6 vol.% single-walled carbon nanotubes in a poly(ethylene glycol)-based dispersion gave a thermal paste that
was as effective as solder for improving thermal contacts. A thermal contact conductance of 20 × 104 W m−2 K−1 was attained. An excessive amount of nanotubes (e.g. 1.8 vol.%) degraded the performance, because of conformability loss.
The nanotubes were more effective than hexagonal boron nitride particles but were less effective than carbon black, which
gave a thermal contact conductance of 30 × 104 W m−2 K−1. 相似文献
2.
A paste in the form of a polyol ester vehicle (liquid) containing 0.6 vol.% nanoclay is an effective thermal interface material.
Nanoclay with a high conformability and hence a small bond line thickness is preferred, namely montmorillonite containing
a quarternary ammonium salt organic modifier (dimethyl dehydrogenated tallow) at 125 meq/100 g clay, after exfoliation by
using the vehicle. When it is used between smooth (0.009 μm) copper surfaces at a pressure of 0.69 MPa, the thermal contact conductance reaches 40 × 104 W/m2 K, in contrast to the corresponding values of 28 × 104 W/m2 K, 28 × 104 W/m2 K, 25 × 104 W/m2 K, and 24 × 104 W/m2 K previously reported for carbon black, fumed alumina, fumed zinc oxide, and graphite nanoplatelet pastes. Between rough
copper surfaces (12 μm), the conductance provided by the nanoclay paste is slightly below those of the other pastes. The superiority of the nanoclay
paste for smooth surfaces is attributed to the␣submicron bond line thickness; the inferiority for rough surfaces is due to
the low thermal conductivity. The conductance provided by the nanoclay paste increases from 31 × 104 W/m2 K to 40 × 104 W/m2 K when the pressure is increased from 0.46 MPa to 0.92 MPa. This pressure dependence is stronger than that of any of the
other pastes studied. 相似文献
3.
The hygrothermal stability of electrical contacts made from silver and graphite electrically conductive pastes is comparatively
evaluated by measurement of the increase in contact electrical resistance during immersion in water at 15°C and 40°C. The
pastes are silver paint, silver paint with a nonconductive epoxy overcoat, silver epoxy, and graphite colloid. Each electrical
contact is made between a seven-strand tin-coated copper wire and the surface of a carbon fiber epoxy-matrix composite. Silver
paint and graphite colloid penetrate the spaces among the 130-μm-diameter strands, but silver epoxy does not. Partly due to its low penetrability and the silver flake (15 μm) preferred orientation, silver epoxy gives contacts of significantly higher resistance than silver paint. Graphite colloid
is comparable to silver epoxy in the resistance. Among the four pastes, silver paint with an epoxy overcoat is most durable,
though it gives slightly higher resistance than silver paint without epoxy. Silver epoxy is less durable than silver paint
without an epoxy overcoat, particularly at 40°C, due to the low hygrothermal stability of epoxy. Graphite colloid is even
less durable than silver epoxy, due to its being water based. 相似文献
4.
Parisa Pour Shahid Saeed Abadi Chia-Ken Leong D.D.L. Chung 《Journal of Electronic Materials》2009,38(1):175-192
Finite element modeling is conducted to understand the factors that govern the performance of thermal interface pastes of
controlled thickness between copper surfaces of controlled roughness. Carbon black paste is lower in thickness than metal
particle paste, so it shows better performance. The performance of both pastes is more influenced by the paste-copper interfacial
conductance than by the paste thermal conductivity. The effects of pressure, paste thickness, and copper surface roughness
on performance are mainly due to the change in fractional filling of the valleys in the copper surface topography. Reasonable
agreement is found between modeling and experimental results. 相似文献
5.
Chia-Ken Leong Yasuhiro Aoyagi D. D. L. Chung 《Journal of Electronic Materials》2005,34(10):1336-1341
This paper addresses thermal interface materials for thermal conduction of excess heat for microelectronic applications. Carbon
black (30 nm) thixotropic paste based on polyol ethers is comparable to carbon black fluidic paste based on polyethylene glycol
(PEG) in its effectiveness as a thermal paste, and in its dependence on pressure history. Prior pressure (up to 0.69 MPa)
application is helpful. The optimum carbon black content is 2.4 vol.% for the thixotropic paste. The thermal contact conductance
across copper surfaces is 30 × 104 and 11 × 104 W/m2-°C for surface roughness of 0.05 μm and 15 μm, respectively. The volume electrical resistivity is 3 × 103 Ω-cm. Boron nitride (BN) (5–11 μm) and graphite (5 μm) thixotropic pastes are less effective than carbon black thixotropic
paste by up to 70% and 25%, respectively, in thermal contact conductance, due to low conformability. 相似文献