Ceramic-metal substrate with differential thermal expansion compensation

摘要

Production of a ceramic-metal substrate involves attaching a first metal (preferably copper) foil layer (3) onto a ceramic layer (2a) surface and then slitting the ceramic layer (2a) by material removal as far as the metal layer (3). The novelty is that: (i) slits (5) are formed in the ceramic layer (2a) at a distance (a) from two or more edges (2a') and extending along the entire length of the edges to form, at both sides of each slit (5), a first ceramic section (2a") adjacent the edge (2a') and a further ceramic section (2a"'), each slit (5) having a width (b) of at least twice the thickness (d) of the ceramic layer (2a); (ii) the metal layer (3) is bent through 180 deg in the slit regions to form two or more U-shaped contacts (7, 7'), respective arms of which form upper contact faces (8, 8'), fixed to the further ceramic sections (2a"') on the substrate top surface, and lower contact faces (9) on the substrate bottom surface, the upper and lower contact face s being parallel to one another and being joined together at the substrate edge; and (iii) the upper and lower contact faces are spaced from one another, in the finished substrate, by at least two ceramic layers (2", 2"') formed respectively by the first ceramic sections (2a"0 and the further ceramic sections (2a"'). The ceramic layer (2a) consists of e.g. aluminium oxide or aluminium nitride ceramic. Also claimed is a substrate made by the above process.