PMIC IAS 17023:2005 Accredited
Precision Measurements and Instruments Corporation
3665 SW Deschutes Street • Corvallis, Oregon 97333-9285
Ph: (541) 753-0607 • Fax: (541) 753-0610
PMIC Testing Services

Thermal Conductivity

PMIC specializes in both in-plane and through thickness thermal conductivity evaluation of fiber composite laminates and sandwich structures. We can measure complex structures such as bonded and fastened joints, including IC chips bonded to heat sink material, thermal resistance of interfaces, multi-layer materials, and thin film materials. Testing can be performed in air or partial atmosphere, vacuum or inert gas.

A partial list of some of the materials we have tested are as follows:

  • Graphite and Carbon
  • Carbon Fibers
  • Silicon Carbide
  • Potting Compound
  • Porous Ceramics
  • Silica Aerogels
  • Carbon-Carbon
  • Silicon
  • Polymers
  • Concrete and Asphalt
  • Textiles
  • Textile Composites
  • Epoxy Resins
  • Fiberglass
  • Glass
  • Dense Ceramics
  • Liquids
  • Plastics
  • Firebrick
  • Cellulose insulation
  • Mineral fiber
  • Wood
  • Invar
  • Aluminum
  • Copper
  • Other metal & alloys

The choice of measurement technique depends upon the type of material, the expected conductivity and the desired test temperature range.

The testing at PMIC satisfies American Society for Testing and Material (ASTM) procedures C177, C518, C1113, C1114, E1225, E1530, and D5470.

SPECIFICATIONS OF THE MEASURING SYSTEMS

1. Guarded Hot Plates System, ASTM C177 – The system is used for testing thermal insulations and other low-density materials having low thermal conductivity. It conforms to ASTM C177 and ISO 8302.

Thermal Conductivity Range 0.01 to 2 W/mK
Mean Sample Temperature Range -175°C (98K) to 204°C (477K)
Sample Size A pair of 6.0" square specimens, up to 2.0" thick
Reproducibility ± 2%
Accuracy ± 3% to ±; 5%

2. Heat Flow Meter System, ASTM C518; E1530 – The instrument is suitable for testing materials having medium to low thermal conductivity in accordance with ASTM C518 and ISO 8301, and E1530.

Thermal Conductivity Range 0.1 to 2 W/mK
Mean Sample Temperature Range -180°C (193K) to 200°C (473K)
Sample Size Customized size
Reproducibility ± 2%
Accuracy ± 5% to ± 8% depending on sample and conductivity

3. Guarded-Comparative-Longitudinal Heat Flow System, ASTM E1225 – This system is ideal for evaluating materials in the moderate to high conductivity range. It conforms to ASTM E1225.

Thermal Conductivity Range 0.2 to 400 W/mK
Mean Sample Temperature Range -228°C (45K) to 600°C (873K)
Sample Size Customized size
Reproducibility ± 2%
Accuracy ± 5% to ± 10% depending on sample and conductivity

4. Thin Heater apparatus, ASTM C1114 – The guarded hot plate method (ASTM C177) for thermal conductivity of insulating panels has numerous limitations for use above 500°C (773K). The thin heater modification (ASTM C1114) has no upper temperature limitation in principle. PMIC has developed this technique to measure 6.0” x 6.0” (152 × 152mm) panels to temperatures in excess of 1200°C (1473K) in air, ideal for refractory bricks and insulation panels. A detailed description was presented at the 17th European Conference on Thermo-physical Properties, September 2005 in Bratislava and also at the ITCC 29 Conference in Birmingham, Alabama.

5. HOT Wire Technique, C1113 – The thermal conductivity of thermally insulating dielectric materials such as ceramics, foams, and polymers with k<5 W/mK is measured using a transient hot wire technique based on ASTM C1113. Measurements are performed in air, vacuum, or inert gas from room temperature up to 500°C (773K). Higher temperatures are available, contact PMIC for more information.

6. Thin Film Thermal Conductivity, D5470 – D5470 is used to determine the thermal conductivity of insulative sheet material from 0.02 to 5 mm in thickness. Specimens are measured using a steady state method based on ASTM D5470. This method is ideal for lower conductivity material such as polymer sheets of thin ceramic plates.

3 Ω is used for dielectric films less than 10um thick mounted on substrates. This technique is based on the pioneering work of David G. Cahill and has become one of the most widely used techniques for measuring thin films. A small metallic heater/thermometer is deposited on the film surface. An AC current at frequency w is applied to the heater and its 3w voltage response is monitored. This voltage increase is used to determine the temperature increase with time and calculate the thermal conductivity of the film.

7. Mathis TCi – A commercially available instrument manufactured by Mathis is also available for determining thermal conductivity and effusivity. This method has several distinct advantages over traditional measurement techniques for thermal conductivity. Measurements can be carried out in minutes thus decreasing the cost, and sample size is practically unlimited. It is based on a modified hot wire technique. It is ideal for lower conductivity materials including foams, polymers, powders, ceramics, and low k metals (<40 W/m-K). Tests can be conducted from -50°C (223K) to 200°C (473K).

8. Liquid Thermal Conductivity – Thermal conductivity of viscous liquids such as pastes, slurries, and oils is measured using a modified ASTM E1225 technique. Measurements can be made from 0°C (273K) to 90°C (363K). Additionally, a hot wire method can also be employed.

Please contact us with all of your Thermal Conductivity needs.