Liquid-cooled integrated substrate and manufacturing method of liquid-cooled integrated substrate

A liquid-cooled integrated substrate in which a metal circuit board made of aluminum or an aluminum alloy is bonded to one surface of a ceramic substrate, one flat surface of a plate-like metal base plate made of aluminum or an aluminum alloy is bonded to another surface of the ceramic substrate, and a liquid-cooling type radiator composed of an extrusion material with flow paths for a coolant integrally formed by extrusion processing is bonded to another flat surface of the plate-like metal base plate by brazing, wherein a brazing material layer is formed in a gap part between the liquid-cooling type radiator and the another flat surface of the plate-like metal base plate, wherein a relation between a thickness t1 of the metal circuit board and a thickness t2 of the plate-like metal base plate satisfies a following expression (1)

• t2/t1≧2 (1)
• where the thickness t1 of the metal circuit board is 0.4 to 3 mm and the thickness t2 of the plate-like metal base plate is 0.8 to 6 mm, wherein the radiator has a hollow inner space that is partitioned by partition plates into the flow paths for the coolant, wherein a relation between a width W (mm) of a flow path and a depth D (mm) of the flow path satisfies 3.3W<D<10W, and wherein a relation between the width W (mm) of the flow path and a width T (mm) of a partition plate satisfies
• −W+1.4<T/W<−1.5W+3.3 (when 0.4≦W≦1.0)
• −0.2W+0.7<T/W<−1.5W+3.3 (when 1.0<W<2.0).