<p>A heat dissipating substrate (1) comprises a first metal-diamond composite layer (11), a second metal-diamond composite layer (12), and a core material layer (10) disposed between the first metal-diamond composite layer (11) and the second metal-diamond composite layer (12). The first metal-diamond composite layer (11) and second metal-diamond composite layer (12) each have a diamond content of less than 50% by volume. The core layer (10) has a coefficient of thermal expansion in a direction parallel to a main surface of 4.5 × 10-6 K-1 - 13 × 10-6 K-1 and a thermal conductivity of 140 W·m-1·K-1 or greater in the direction of thickness. Thus, a low-cost heat dissipating substrate having a coefficient of thermal expansion and high thermal conductivity suitable for mounting or holding a semiconductor element is provided.</p>
