Thermal interface materials thermally conductive adhesives

The use of thermally conductive adhesives in electrical/electronic assemblies has been described [36,38]. In these applications, temperature rises due to evolution of heat from components including resistors, transformers, etc. in high-density circuits is often critical and a cause for concern. Heat sinks and fans are mechanical means that are used to keep the temperature of the electronics at a minimum, but materials also play a critical role. Materials are used to couple the electronics and heat sinks or fan sinks, as well as to couple interfaces with lids, baseplates, and heat spreaders. 

Thermal interface materials are slurries of thermally conductive particles, usually diamond or metallic oxides, suspended in liquid or low modulus adhesive. They are designed to be flexible or slightly fluid to maintain good thermal contact during temperature cycling. 

It is clear that CNTs have many advantages over other carbon materials in terms of electrical and thermal properties. These properties offer CNTs great potential for wide applications in field emission, conducting plastics, thermal conductors, energy storage, conductive adhesives, thermal interface materials, structural materials, fibers, catalyst supports, biological applications, and ceramics and so on [35]. 

Voids at the interface may be formed by the growth process during interface formation, by the accumulation of defects due to mass transport processes, or by the loss of material by diffusion. Voids at the interface are evidenced by low adhesion, high contact resistance, and possibly low thermal conductivity. Interfacial voids are studied by careful TEM sample preparation and by surface analysis of the failure surfaces after failure. 

Many new polymers have been synthesized and tested for their proton conductivity, methanol permeability, thermal as well as mechanical stability, electrode-manbrane interface connectivity, etc., aiming at improvanent in m brane performance for fuel cell applications. These efforts seem to continue with insightfirl vision and strong commitment in the fnture. However, only a handful of polymers are currently being used as the materials for commercial apphcations, and they are not necessarily the polymers of the best performance properties. This is mainly due to the cost factor that governs the present membrane rrrarket. The fuel cell performance of membranes is, on the other hand, known primarily ruled by the various factors, mainly, membrane fuel permeability, electrode-membrane adhesion (or compatibility), thermal and mechanical stabilities. The knowledge of the effects of these factors on... 

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