Patent ID: 6900073

Claim:
A method for flattening sintered ceramic electronic packaging substrates comprising: providing a plurality of sintered ceramic electronic packaging substrates having opposing faces with undesired camber, the ceramic substrates having a length and width and a thickness between the faces substantially less than the ceramic substrate length and width; providing a plurality of spacers having a length and width at least as great as the length and width of the ceramic substrates, and a thickness substantially less than the spacer length and width, the spacers further having a thermal conductivity at least as great as a thermal conductivity of the ceramic substrates; stacking the ceramic substrates and spacers such that the spacers are disposed between each of the ceramic substrates; providing a heat transfer medium along sides of the stack of the ceramic substrates and spacers, the heat transfer medium having an inside length and width substantially equal to the spacer length and width; applying heat to sides of the stacked ceramic substrates and spacers via the heat transfer medium to a maximum temperature not exceeding liquidus or softening temperature of the ceramic substrates; applying pressure to the stacked ceramic substrates and spacers in a direction normal to the faces of the ceramic substrates while maintaining the maximum temperature to reduce the camber of the ceramic substrate faces; and cooling the ceramic substrates and maintaining reduced camber of the substrate faces.