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Coefficient of Thermal Expansion (CTE)

Definition: The coefficient of thermal expansion is defined as the fractional increase in the length per unit rise in temperature.

The coefficient of thermal expansion for a material is usually specified over a temperature range because it varies depending on the temperature. The following values are given for a temperature around 20 C. CTE is usually given in units of um/m/C or ppm/C.



Coefficients of Thermal Expansion (CTE) of some common materials

Material CTE (ppm/C) Material CTE (ppm/C)
AlAs 4.9 InAs 4.52
AlP 4.5 InP 4.75
Alumina 6-7 InSb 5.37
AsSb 4 Invar 1.3
Copper 16.7 Kovar 5.9
Cu/I/Cu 8.4 Molybdenum 7.0-7.1
Cu/Mo/Cu 6 Polymers 50-200
Cu/Mo-Cu/Cu 6-10 S-glass 16
E-glass 54 Silicon 2.6
Epoxy 55 Silicon Nitride (Si3N4) 3.2
Fused Silica 0.55 Silicone resins 30-300
Gallium Arsenide (GaAs) 6.86 Tin-Lead Solder 27
GaP 4.5 Titanium 9.5
GaSb 7.75 Tungsten 5.7-8.3
Germanium (Ge) 5.8


Sources:
www.owlnet.rice.edu/~msci301/ThermalExpansion.pdf
www.matweb.com
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