Thermal Properties and Thermal Analysis:
The chapter provides a summary of the fundamental concepts that are needed to understand the heat capacity C P, thermal conductivity κ, and thermal expansion coefficient α L of materials. The C P, κ, and α of various classes of materials, namely, semicond
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Thermal Prop
19. Thermal Properties and Thermal Analysis: Fundamentals, Experimental Techniques and Applications
The selection and use of electronic materials, one way or another, invariably involves considering such thermal properties as the specific heat capacity (cs ), thermal conductivity (κ), and various thermodynamic and structural transition temperatures, for example, the melting or fusion temperature (Tm ) of a crystal, glass transformation (Tg ) and crystallization temperature (Tc ) for glasses and amorphous polymers. The thermal expansion coefficient (α) is yet another important material property that comes into full play in applications of electronic mater-
19.1
Heat Capacity ...................................... 386 19.1.1 Fundamental Debye Heat Capacity of Crystals .................... 386 19.1.2 Specific Heat Capacity of Selected Groups of Materials ... 388
19.2 Thermal Conductivity ........................... 19.2.1 Definition and Typical Values ...... 19.2.2 Thermal Conductivity of Crystalline Insulators.............. 19.2.3 Thermal Conductivity of Noncrystalline Insulators ........ 19.2.4 Thermal Conductivity of Metals ...
391 391 391 393 395
19.3 Thermal Expansion .............................. 396 19.3.1 Grüneisen’s Law and Anharmonicity.................... 396 19.3.2 Thermal Expansion Coefficient α . 398 19.4 Enthalpic Thermal Properties ................ 398 19.4.1 Enthalpy, Heat Capacity and Physical Transformations ..... 398 19.4.2 Conventional Differential Scanning Calorimetry (DSC) ......... 400 19.5 Temperature-Modulated DSC (TMDSC)..... 19.5.1 TMDSC Principles........................ 19.5.2 TMDSC Applications .................... 19.5.3 Tzero Technology.......................
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References .................................................. 406 The new Tzero DSC has an additional thermocouple to calibrate better for thermal lags inherent in the DSC measurement, and allows more accurate thermal analysis.
ials inasmuch as the thermal expansion mismatch is one of the main causes of electronic device failure. One of the most important thermal characterization tools is the differential scanning calorimeter (DSC), which enables the heat capacity, and various structural transition temperatures to be determined. Modulated-temperature DSC in which the sample temperature is modulated sinusoidally while being slowly ramped is a recent powerful thermal analysis technique that allows better thermal characterization and heat-capacity measurement. In addition, it
Part B 19
The chapter provides a summary of the fundamental concepts that are needed to understand the heat capacity CP , thermal conductivity κ, and thermal expansion coefficient αL of materials. The CP , κ, and α of various classes of materials, namely, semiconductors, polymers, and glasses, are reviewed, and various typical characteristics are summarized. A key concept in crystalline solids is the Debye theory of the heat capacity, which has been widely used for many decades for calculating the CP of crystals. The the
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