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To: Mani1 who wrote (77886)	4/22/2002 7:02:14 AM
From: Bill Jackson	Respond to of 275872

Mani, 95% by volume or density? Big difference in heat conduction, if each particle is isolated in plastic that would be the case, which would occur at 95% by weight, by volume however I believe that at some point you reach a certain density of particles where there is enough direct contact between the diamond particles to allow for larger w/m.k, esp with a MacAdam size distribution among the diamond particles. (A MacAdam size spread has a graded particle distribution such that there are zero voids....now that cannot be achieved in reality, but there is a level where there is a high level of direct contact between the particles, and this makes many parallel paths. This direct contact enhances the conductivity of heat(and the load bearing ability in the case of roads)This is also used in DAG type paint on RF shielding for tubes and silver bearing heat sink compounds that can be varied from insulating to conducting by varying the size distribution and loading) MacAdam was the famous Scot who invented the graded particle size concept, leading to MacAdamized roads, add tar and you get tar-MacAdamized roads....tarmac, also called asphalt for it's famous ability to keep the snakes out of Eire. Of course I am speculating and Mani does this for a living, so I am just doing a first principal analysis as to what might be the reason for making compound heat sink materials that just add costs? by the use of diamond particles? Of course diamonds are costly, but industrial diamond of small size grit, esp with a lot of smalls to fill the voids, is a lot cheaper than Lizzie Taylors large lumps Bill