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Laser Flash Thermal Conductivity 
Specifications
Thermal conductivity of constituent materials plays a critical role in many applications requiring component cooling or heat insulation. These applications include electronic packaging, design of new heat sink materials, advanced structural ceramics used in propulsion, and many other high thermal demand situations. Over the past few decades, the laser flash method has developed into one of the most accurate and flexible techniques for the measurement of the thermal conductivity of various kinds of solids, powders and liquids.  

Engineers at CMC Laboratories were some of the original developers of laser flash thermal conductivity testing.  With over 30 years in TC measurement analysis coupled with CMC's extensive background in materials science, we are able to provide extremely precise measurement results as well as a strong understanding of the specific material properties or defects that influence thermal conduction.
Thermal Conductivity & Diffusivity
Measurement Range
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CMC's Laser Flash system covers the widest measuring range of all techniques, 0.1 up to 2000W/m*K for Thermal Conductivity and 0.01 up to 1000 mm2/s for Thermal Diffusivity.  

(Values may vary for special applications)
Accuracy & Repeatability
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Highest Accuracy and Repeatability, +/- 1.5-3% depending on material and specimen construction.  

(Values may vary for special applications)
Materials Analyzed
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    - Ceramics (AlN, Alumina, BeO, etc)
    - Ceramic composites
    - Metals
    - Metal matrix composites
     - Semiconductors
     - Building materials (Concrete, etc)
     - Glasses and other dielectrics
     - Sapphire and diamond
    - Plastics (with and without fillers)
     -Polymers (with and without fillers)
Acceptable Sample Size
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CMC's Laser Flash system was designed to accept a wide range of sample sizes in order to test realistic components without size reductions.  (This avoids limitations common in many other laser flash systems of 10-25mm in diameter).  CMC can test thermal conductivity on the following samples ranges.

        Sample Diameter: 3mm - 150mm
        Sample Thickness: 0.1mm - 6mm
The Laser Flash Measurement

Laser Flash Thermal Diffusivity (TD) measurements consists of pulse heating the front side of a sample surface with a short laser pulse, and then measuring the time evolution of the back surface temperature using an infrared detector.  The resulting temperature profile curve is tailored using a one dimensiontal heat flow model (1D Model). The sample's TD is then extracted from the model and thermal conductivity (TC) can be calculated using the TD, density, and specific heat.  Sample thickness and sample size can affect the 1D model and may effect the accuracy of the TD results.  CMC Laboratories has developed a 1D model that allows for proper curve fitting evaluation to insure the 1D heat flow condition has been met. CMC can adjust apertures in the system to optimize the 1D condition.
Temperature and Enviromental Options
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 Samples can be tested at temperatures from RT to 350°C 
Standard Compliance​​
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CMC's Laser Flash system complies with national and international standards ASTM E-1461, DIN 30905, and DIN EN 821.
Thermal Diffusivity = α = 0.1388 L2/ t1/2m2/s
Thermal Conductivity = k = Cp p α
Cp = Heat Capacity        p = Density
Application Examples: Aluminum, Copper, and Graphite

Aluminum, Copper, and Graphite are perfect materials to show the performance of CMC's Laser Flash Thermal Conductivity measurement capability as a function of temperature.  Measured values are within 2% of published literature values.  CMC's system has been commonly used to certify standards for NIST as well as routineprocess monitoring coupons for the ceramics, telecommunications, aerospace, and semiconductor industries. 

Thermal Conductivity of Layered Structures


Utilizing the Laser Flash technique and advanced heat flow models, CMC has the capability of measuring the thermal conductivity of layered structures.
Typically this technique is used to find the thermal conductivity of an interlayer between two materials with known thermal conductivity. The interlayer thermal conductivity includes both the bulk thermal conductivity of the interlayer and the thermal impedance of the interfaces.

Here are some typical examples of how this technique is used:
* To determine the thermal conductivity of thermal interface materials such as thermal pads or thermal greases.
* To determine the actual thermal conductivity of die attach layers, particularly high thermal conductivity epoxy die attach, where resin segregation can have a large impact on thermal interface impedance