Reliability of materials for the thermal management of electronics

Risto Hienonen, Jari Keskinen, Timo Koivuluoma

Research output: Book/ReportReportProfessional

Abstract

The main goal of this project was to research the properties and reliability of the thermal interface materials used in electronics. The selected materials for measurements and tests contained elastic pad sheets, phase change materials and greases. The thermal impedance at pressures of 0,1...0,8 MPa was measured from the 34 materials. From these 14 materials were selected for the reliability tests. A new measurement method for thermal impedance and a new type of test structure for material testing was developed. The new test structure for materials was designed for use in environmental tests. The test structure makes it possible to select test surface quality, test pressure and material thickness. The materials were tested in various environmental conditions (high/low temperature, temperature/humidity cycle, temperature cycling) to see how their properties change in these conditions and what is the life endurance in use. The main criteria for evaluation of materials was the measured thermal impedance (K·cm2/W) at power densities from 10 to 25 W/cm2. The high power density means that samples are heated during the measurements into the high operating temperature. Greases, phase change pads and graphite pads had the lowest impedance value. The measured thermal impedance showed that the pressure and the wettability of materials have in many cases a larger effect on the impedance than the thermal conductivity of the bulk material. Therefore the impedance should be measured with the low pressures (< 0,3 MPa), which are achievable in practical solutions. The tested materials (14 types) performed quite well in the reliability tests, although there were some samples, which had quite large changes of impedance values. The long term behaviour of the tested materials seems to be good. Quite important observation of the tests is that the variation from sample to sample in initial and final measurements is larger than the changes during the tests. Therefore the user should take care of the surface quality and contact pressure while calculating the total variation of thermal impedance for the whole life cycle of products.
Original languageEnglish
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Number of pages149
ISBN (Electronic)951-38-6872-9
ISBN (Print)951-38-6871-0
Publication statusPublished - 2006
MoE publication typeD4 Published development or research report or study

Publication series

NameVTT Publications
PublisherVTT
No.619
ISSN (Print)1235-0621
ISSN (Electronic)1455-0849

Fingerprint

Electronic equipment
Lubricating greases
Surface properties
Thermal management (electronics)
Temperature
Materials testing
Phase change materials
Wetting
Hot Temperature
Life cycle
Thermal conductivity
Atmospheric humidity
Graphite
Durability

Keywords

  • thermal interface material
  • electronics
  • measurements
  • thermal impedance
  • thermal conductivity
  • phase change materials
  • reliability
  • environmental testing

Cite this

Hienonen, R., Keskinen, J., & Koivuluoma, T. (2006). Reliability of materials for the thermal management of electronics. Espoo: VTT Technical Research Centre of Finland. VTT Publications, No. 619
Hienonen, Risto ; Keskinen, Jari ; Koivuluoma, Timo. / Reliability of materials for the thermal management of electronics. Espoo : VTT Technical Research Centre of Finland, 2006. 149 p. (VTT Publications; No. 619).
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Hienonen, R, Keskinen, J & Koivuluoma, T 2006, Reliability of materials for the thermal management of electronics. VTT Publications, no. 619, VTT Technical Research Centre of Finland, Espoo.

Reliability of materials for the thermal management of electronics. / Hienonen, Risto; Keskinen, Jari; Koivuluoma, Timo.

Espoo : VTT Technical Research Centre of Finland, 2006. 149 p. (VTT Publications; No. 619).

Research output: Book/ReportReportProfessional

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N2 - The main goal of this project was to research the properties and reliability of the thermal interface materials used in electronics. The selected materials for measurements and tests contained elastic pad sheets, phase change materials and greases. The thermal impedance at pressures of 0,1...0,8 MPa was measured from the 34 materials. From these 14 materials were selected for the reliability tests. A new measurement method for thermal impedance and a new type of test structure for material testing was developed. The new test structure for materials was designed for use in environmental tests. The test structure makes it possible to select test surface quality, test pressure and material thickness. The materials were tested in various environmental conditions (high/low temperature, temperature/humidity cycle, temperature cycling) to see how their properties change in these conditions and what is the life endurance in use. The main criteria for evaluation of materials was the measured thermal impedance (K·cm2/W) at power densities from 10 to 25 W/cm2. The high power density means that samples are heated during the measurements into the high operating temperature. Greases, phase change pads and graphite pads had the lowest impedance value. The measured thermal impedance showed that the pressure and the wettability of materials have in many cases a larger effect on the impedance than the thermal conductivity of the bulk material. Therefore the impedance should be measured with the low pressures (< 0,3 MPa), which are achievable in practical solutions. The tested materials (14 types) performed quite well in the reliability tests, although there were some samples, which had quite large changes of impedance values. The long term behaviour of the tested materials seems to be good. Quite important observation of the tests is that the variation from sample to sample in initial and final measurements is larger than the changes during the tests. Therefore the user should take care of the surface quality and contact pressure while calculating the total variation of thermal impedance for the whole life cycle of products.

AB - The main goal of this project was to research the properties and reliability of the thermal interface materials used in electronics. The selected materials for measurements and tests contained elastic pad sheets, phase change materials and greases. The thermal impedance at pressures of 0,1...0,8 MPa was measured from the 34 materials. From these 14 materials were selected for the reliability tests. A new measurement method for thermal impedance and a new type of test structure for material testing was developed. The new test structure for materials was designed for use in environmental tests. The test structure makes it possible to select test surface quality, test pressure and material thickness. The materials were tested in various environmental conditions (high/low temperature, temperature/humidity cycle, temperature cycling) to see how their properties change in these conditions and what is the life endurance in use. The main criteria for evaluation of materials was the measured thermal impedance (K·cm2/W) at power densities from 10 to 25 W/cm2. The high power density means that samples are heated during the measurements into the high operating temperature. Greases, phase change pads and graphite pads had the lowest impedance value. The measured thermal impedance showed that the pressure and the wettability of materials have in many cases a larger effect on the impedance than the thermal conductivity of the bulk material. Therefore the impedance should be measured with the low pressures (< 0,3 MPa), which are achievable in practical solutions. The tested materials (14 types) performed quite well in the reliability tests, although there were some samples, which had quite large changes of impedance values. The long term behaviour of the tested materials seems to be good. Quite important observation of the tests is that the variation from sample to sample in initial and final measurements is larger than the changes during the tests. Therefore the user should take care of the surface quality and contact pressure while calculating the total variation of thermal impedance for the whole life cycle of products.

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PB - VTT Technical Research Centre of Finland

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Hienonen R, Keskinen J, Koivuluoma T. Reliability of materials for the thermal management of electronics. Espoo: VTT Technical Research Centre of Finland, 2006. 149 p. (VTT Publications; No. 619).