ASTM D5470 Based Thermal Interface Material (TIM) Tester

LW-9389 TIM Thermal Interface Material Tester

Thermal impedance and thermal conductivity are two major properties of Thermal Interface Materials (TIM). 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. We can provide a side-by-side comparison of several TIMs under the exact same test conditions. To do this, we use Long Win’s LW-9389 TIM Thermal Interface Material Tester, which is used by many TIM manufacturers worldwide to characterize their materials.


What Materials Can Be Tested and How Accurate?

ASTM D5470 TIM Tester

TIM Tester ASTM D5470

Thermal Interface Material Tester can test almost any thermal interface materials including:

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

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)

Test Range and Accuracy:

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


The test is done based on ASTM D5470 standard.




Features of LW-9389 TIM Thermal Conductivity and Resistance Tester

  1. Follows ASTM D 5470-06 Standard.
  2. Suitable for thermal resistance and equivalent thermal conductivity testing on the Z axis of grease, thermal pad and board.
  3. Good reproducibility and repeatability.
  4. Thermal resistance test under a vairety of press load and heating power conditions.
  5. Controlled temperature of heating and cooling meter bars.
  6. Long term reliability test.
  7. Automatic software controls designated testing conditions.
  8. Automatic data acquisition by PC.
  9. Measurement range: Thermal impedance > 0.01°Ccm2/W; Accuracy ± Thermal conductivity < 20 W/m°C





Calculations:According to Fourier’s Law:

Qh: Heat flux on the hot side

Qc: Heat flux on the cold side

Km: Thermal conductivity of meter bar’s material

A: Cross area of meter bar

Th1, Th3 ,Tc1 ,Tc3: Temperature points on the meter bar

X1, X2, X5, X6: Distance between the points on the meter bar

As measuring temperature of Th1, Th3 ,Tc1 ,Tc3, Q, Qc can be calculated and the average heat flux through specimen can be known by:

Extrapolate Th and Tc, which are at contact surfaces of specimen.









Determine Thermal Conductivity and Contact Resistance:

In ASTM D 5470-06 standard, the linear correlation of thermal resistance and thickness were measured based on one specimen with three kinds of thickness. Secondly, the values were extrapolated while the thickness is equal to zero, which is contact resistance. Thirdly, reciprocal of the slope is thermal conductivity which is called apparent thermal conductivity.

Test conducted by LW-9389


Plot test result:

Contact Resistance is 0.4732°C*cm2/W. Thermal conductivity is:

Total Thermal Impedance – Grease or Pad:

Thermal Impedance of MCPCB:

Total Thermal Impedance = I_MCPCB+ Ic_Grease + Ic_Grease

Step 1: Measure Grease Impedance

Step 2: Measure Grease & MCPCB Total Impedance

Step 3: Apparent Thermal Conductivity Equal Thickness Divide by MCPCB Impedance

Result of Thermal Grease

Result of Thermal Pad





    • 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


Reserve Laboratory:

Please let us know the date, time and apparatus you would like to reserve or if you have any other questions about our machines.


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