Hard substrate materials

Updated October 22 2006

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Hard substrates include ceramics such as alumina, aluminum nitride and beryllium oxide, and are desirable for applications where bare die (chips) are used such as in a hybrid module. Ceramics are used because they can withstand the extreme heat used in wirebonding.

Semiconductor substrates such as GaAs, InP and silicon are used in manufacturing RFICs.

Some of these numbers came from Aeroflex, TriQuint, CREE.

Material	Symbol or formula	Dielectric constant	Dissipation factor (tan)	Coefficient of thermal expansion ppm/°C	Thermal conductivity (W/m°C)	Mass density (gr/cc)
Alumina 99.5 %	Al₂O₃	9.8	0.0001	8.2	35	3.97
Alumina 96%	Al₂O₃	9.0	0.0002	8.2	24	3.8
Aluminum Nitride	AlN	8.9	0.0005	7.6	290	3.26
Beryllium Oxide	BeO	6.7	0.003	6.05	250
Gallium Arsenide	GaAs	12.88	0.0004	6.86	46	5.32
Gallium Nitride	GaN					6.1
Indium Phosphide	InP	12.4
Porcelain		6.5
Quartz		3.8	0.0001	0.6	5
Sapphire ^(note1)		9.3, 11.5
Silicon (high resistivity)	Si (HRS)			2.5	138	2.33
Silicon (low resistivity)	Si (LRS)
Silicon Carbide	SiC	10.8	0.002	4.8	350	3.2

Note 1. Anisotropic dielectric material, Er=9.3 perpendicular to C-axis, 11.5 parallel to C-axis.

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