For most calculations regarding the thermal analysis of electronic systems, thermal conductivities of solid materials are required. It is felt that many designers would welcome a comprehensive list showing these values for certain classes of objects, such as PCB materials, leadframes, molding compounds, alloys etc.. This issue starts with 45 leadframe materials, the data for which is published by the suppliers. Of course, such a list can never be complete, and most certainly, materials that have been marketed recently are missing. It should be stressed that the accuracy of the data is not guaranteed.
It is often not recognized that the accurate measurement of thermal conductivity is still a very challenging task, and an abundance of literature describing the substantial differences quoted by established Standard Laboratories testifies to this assertion.
In addition, it is usually not known how the suppliers calculate this data. When accurate predictions of temperature are the objective of the analysis, it is recommended that measurements be taken in situ, by imposing a variety of well-known boundary conditions to the package under study, and fitting the unknowns of the package to match the measured temperatures.
BILL HAKALA says
Hi, I was curious about most recent data on conductivity through elastomers like HNBR with modest amounts of carbon black and some mineral fillers and perhaps fibers like aramids.
I doubt there is much specific unfo, but good to see at least regular NBR is mentioned although I’m more interested above 100C.
Thanks.
Admin says
I am not sure what your application is but mostly HBNR is used as O-rings, damping blocks and many applications outside the domain of electronics cooling. One reason they look for high (well, relatively) thermal conductivity is to prevent so-called heat build up caused by mechanical load. It is difficult to find reliable values, especially because of the material’s compliance. I highly recommend to follow my advice to design an experiment in situ with the objective of fitting the unknown material property to a numerical model, mimicking as much as possible the real conditions. Hence, apply hard boundary conditions everywhere (no free convection or fans), apply the same load, same size etc.
Hope this helps.
-Clemens Lasance
Manu says
Can you list out inorganic fillers, metallic ones, that are used today to improve HEAT CONDUCTIVITY OF BLOWN PE FOAMS, PP FOAMS, PVC FOAMS. BLOWN RUBBER ARE USED FOR COVERING COPPER PIPES FOR IMPARTING INSULATION.
Admin says
Hi Manu,
Your question has been forwarded to the author of this article, Clemens J. M. Lasance.
Regards,
Electronics Cooling
Admin says
I am not sure if I understand your question. You talk about imparting insulation, and then about increasing its thermal conductivity. Those two don’t match. Could you please be more specific about the application?
-Clemens Lansance