A brazing material having 0.25-0.9 wt % of titanium oxide added to a basic formula consisting of 60-94.25 wt % Ag, 5-30 wt % Cu and 0.5-4.5 wt % of an active metal is processed to form a paste, which is applied to an AlN substrate and overlaid with a copper plate and heat treated to form a joint between the AlN substrate and the copper plate. A resist is applied to the copper plate to form a circuit pattern, which is etched to form a metallized circuit, thereby producing a metal-ceramics composite substrate capable of operation on high electrical power. The substrate is improved in various characteristics of a power module device over the composite substrates produced by using the conventional brazing materials.