ASTM D5470 Based Thermal Interface Material (TIM) Tests

LW-9389 TIM Thermal Interface Material Tester 

Thermal Impedance & Thermal Conductivity

Long Win’s LW-9389 Thermal Interface Material TIM Tester is used by many TIM manufacturers worldwide to conduct thermal interface material tests to measure and calculate the thermal impedance and conductivity of Thermal Interface Materials (TIM). Thermal impedance and thermal conductivity are two major properties of TIMs. Although their values can be found on manufacturers’ datasheets, these values are often measured based on different standards (e.g. ASTM D5470, ASTM C-177, etc.) or under different test conditions (e.g. environment, contact pressure, etc.). In our thermal laboratory, we can help customers characterize the thermal impedance and thermal conductivity values based on ASTM D5470-06 standard under specified test conditions. Researchers are welcome to reserve our lab to conduct tests or have our thermal engineers conduct thermal impedance and conductivity tests and send an electronic report with results. We can provide a side-by-side comparison of several TIMs under the exact same test conditions. 

What Materials Can Be Tested and How Accurate?

TIM Tester

Almost all thermal interface materials can be tested:

  • Thermal Grease
  • Gap Filler Pads
  • Phase Change Materials
  • Thermal Tapes
  • Graphite Sheets
  • Thermally Conductive Insulators

In addition, the following materials can be tested:

  • Ceramics
  • Metals
  • Plastics
  • Printed Circuit Boards (PCB)
  • Metal Core PCB (MCPCB)
  • Metal-based Copper Clad Laminates (MCCL)


  • Thermal Impedance
  • Thermal Conductivity
  • Contact Impedance
  • Pad Deflection

Test Range and Accuracy:

  • Thermal Impedance: > 0.01 °C-cm²/W
  • Thermal Conductivity: < 20 W/m-°C
  • Accuracy: ±5%.


Gap and TIM



Features of LW-9389 TIM Thermal Conductivity and Resistance Tester


Thermal Conductivity and Resistance Tester


  • Based on ASTM D5470
  • Good repeatability and reproducibility
  • Suitable for measuring thermal impedance and conductivity of grease and pad
  • Automated setting of press load and input power
  • Automated setting of temperatures of hot surface, cold surface and average temperature
  • Suitable for reliability tests
  • Automated DAQ and output in Excel

SpecificationsTIM Test

  • Press Load Range: 4 ~ 50 kgf
  • Max. Heating Power: 160 W
  • Max. Heating Temperature: 180℃
  • Constant Temperature Range: Ambient+3℃~50℃
  • Overall Dimension: 1.37 (W) × 0.87 (D) × 1.88 (H) m (Ref.)
  • Power Source: AC220V, 10 Amp, Single Phase




The test is performed based on ASTM D5470:

ASTM D5470


Calculation of Thermal Conductivity and Contact Impedance:

In ASTM D5470-06 standard, the linear correlation of thermal impedance and thickness are measured based on one specimen with three different thicknesses. The values are extrapolated with the thickness set to zero, which is contact impedance. The thermal conductivity, also known as apparent thermal conductivity, can be found by taking the reciprocal of the slope.

Thermal Conductivity and Contact Impedance



Example of Software Interface – Pad/Grease Impedance Test:

Impedance Test



What is the cost and turn-around time of the test?

Testing of thermal interface materials (TIM) at MyHeatSinks are accurate, quick and cost effective. The average time for testing one material is 2-4 hours. However, due to equipment availability and scheduling, the typical turn-around time is one week. In case of a major holiday or an event like COVID-19 pandemic, the turn-around time will increase to two weeks.


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