Pure beryllium oxide (BeO) belongs to the cubic crystal system. Density is 3.03g / cm3. Melting point is 2570 ℃. It has a high thermal conductivity. Aluminum is almost equal with copper, thermal conductivity λ200-250W / (mK), there is a good thermal shock resistance. Dielectric constant 6 ~ 7 (0.1MHz). Dielectric loss tangent value of about 4 × 10-4 (0.1GHz).