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