TY - GEN
T1 - Non-uniform thermal properties of an alumina granule/epoxy potting compound
AU - Maddox, John F.
AU - Knight, Roy W.
AU - Bhavnani, Sushil H.
PY - 2010
Y1 - 2010
N2 - In harsh environments, including high shock and vibration, magnetic devices such as transformer coils are potted to enhance thermal performance and provide mechanical protection. One potting compound frequently used is epoxy containing alumina particles. A nominally isotropic and uniform potting compound consisting of about 70 to 80% by volume 14-28 mesh (0.6 to 1.2 mm across) alumina granules in low viscosity epoxy was tested to determine its thermal properties. Examination by optical microscopy revealed that there was significant variation in volume fraction of alumina particles by location. The specific heat and thermal conductivity of the compound were measured using a Differential Scanning Calorimeter and guarded heater method based on the ASTM D5470-06. The thermal properties were found to vary with time, location, and temperature; with the specific heat ranging from 1.00 J/g°C ± 14% at 25°C to 1.22 J/g°C ± 12% at 125°C and an apparent thermal conductivity of 2.56 W/m·K ± 23%. Users of such compounds should be aware that the thermal properties are not necessarily constant in time or uniform, and assuming that they are could lead to significant errors when modeling their performance.
AB - In harsh environments, including high shock and vibration, magnetic devices such as transformer coils are potted to enhance thermal performance and provide mechanical protection. One potting compound frequently used is epoxy containing alumina particles. A nominally isotropic and uniform potting compound consisting of about 70 to 80% by volume 14-28 mesh (0.6 to 1.2 mm across) alumina granules in low viscosity epoxy was tested to determine its thermal properties. Examination by optical microscopy revealed that there was significant variation in volume fraction of alumina particles by location. The specific heat and thermal conductivity of the compound were measured using a Differential Scanning Calorimeter and guarded heater method based on the ASTM D5470-06. The thermal properties were found to vary with time, location, and temperature; with the specific heat ranging from 1.00 J/g°C ± 14% at 25°C to 1.22 J/g°C ± 12% at 125°C and an apparent thermal conductivity of 2.56 W/m·K ± 23%. Users of such compounds should be aware that the thermal properties are not necessarily constant in time or uniform, and assuming that they are could lead to significant errors when modeling their performance.
KW - Spatially varying thermal properties
KW - Time varying thermal properties
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U2 - 10.1109/ITHERM.2010.5501342
DO - 10.1109/ITHERM.2010.5501342
M3 - Conference contribution
AN - SCOPUS:77955212431
SN - 9781424453429
T3 - 2010 12th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, ITherm 2010
BT - 2010 12th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, ITherm 2010
T2 - 2010 12th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, ITherm 2010
Y2 - 2 June 2010 through 5 June 2010
ER -