Patent ID: 8449143

Claim:
A metal base circuit board comprising: a plurality of insulating layers and circuits that are alternately provided on top of a metal plate, and a white film that is provided at least on top of the insulating layer that is furthest from the metal plate, wherein the reflectivity of said white film for light having three wavelength ranges of 450 to 470 nm, 520 to 570 nm, and 620 to 660 nm is 80% or greater, and wherein at least one of said insulating layers contains25 to 50% by volume of a thermosetting resin, the remainder being two types of inorganic filler having average grain sizes in a range of 0.6 to 2.4 μm and in a range of 5 to 20 μm, and the shapes thereof being spherical, crushed, or scale-like.