In-Plane Thermal Diffusivity and Resistance Test

LW-9614 In-Plane Thermal Diffusivity and Thermal Conductivity Measurement Apparatus

LW-9614 In-Plane Thermal Diffusivity and Thermal Conductivity Measurement Apparatus is based on the Angstrom Method. This can be applied for isotropic and anisotropic sheet materials with high thermal conductivity. Our apparatus provides a sinusoidal temperature wave and automatically measures corresponding temperature differences and amplitudes at certain positions of the material. The thermal diffisuvity of the material can then be calculated afterwards.

Experimental Items:

  1. Thermal Diffusivity
  2. Thermal Conductivity
  3. Sinusoidal Temperature Waveform
  4. Correlation of Amplitude and Phase Difference

Key Factors of Measurement

  • Temperature
  • Time (Phase Shift)
  • Thickness: 20 ~ 600 μm
  • Thermal Diffusivity: 0.05 ~ 10 cm2/s
* “Specific heat” and “density” of the specimen can be manually keyed-in, and the software will calculate a corresponding thermal conductivity.
* In LW–9614 system, measurement devices for density and specific heat are excluded.

Apparatus Features

  • Based on Angstrom Method
  • Specimens: Highly thermal conductive films/sheets Ex: Graphite, copper, aluminum, etc.
  • Thermal Diffusivity: 0.05 ~ 10 cm2
  • Thermal Conductivity >15 W/m
  • With high in-plane thermal diffusivity, graphite has been widely applied in smart phones, tablets, and many consumer electronics to remove the “hot spot” and dissipate heat



Angstrom Method (1863) based on one-dimensional transient heat transfer equation. The system provides a periodical heating and cooling condition and deduce thermal diffusivity.

α : thermal diffusivity

h : heat loss coefficient


Analytical Solution:

Boundary Condition:

T is periodic at x=0      at x=∞

Solution of Thermal Diffusivity:

  1. A long specimen receives periodic temperature waveform on one side.
  2. Measure the temperature of T1 and T2, the amplitude of M and N, and the phase shift between two corresponding waveforms (dt).
  3. Finally, thermal diffusivity (α).


  1. Sinusoidal Temperature Waveform
  2. Specimens and the Clamping Mechanism for Temperature Sensors
    • Distance between the two sensors from 10 to 100 mm
    • Specimen Dimension:
      • Length: > 300 mm
      • Width: 20 ~ 30 mm
      • Thickness: 0.02 ~ 0.6 mm
    • Tension stress for Specimens: 100 ~ 1000 gf/mm²
  3. Software for DAQ Analysis
    1. Calculate the correlation of amplitudes and phase differences
    2. Get the value of thermal diffusivity
    3. Specific heat and density of the specimen can be manually keyed-in for parameters acquiring a corresponding thermal conductivity
  4. Over Dimension: 90 (W) x 65 (D) x 164 (H) cm


  • Heating & Cooling Unit: 20 x 20 mm (Ref.)
  • Specimen Dimension:
    • Length: >200 mm
    • Width: 20 ~ 30 mm
    • Thickness: 0.02 ~ 0.6 mm
  • Amplitude and Sine Waves Generator are PC-based controlled
  • Tension Strength of Specimens: >100 gf/mm2
  • Overall Dimension: 0.9 (W) x 0.65 (D) x 1.65 (H) m
  • Power Source: AC 220 V, 5 Amp, single phase

Reserve Laboratory:

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