Multi-level metalization on a ceramic substrate

Abstract

The invention relates to a method for producing a copper multi-level metallization on a ceramic substrate ( 4 ) consisting of AIN or Al 2 O 3 . High power regions ( 1 ) with metallization having a high current-carrying capacity and low power regions ( 2 ) with metallic coatings having a low current-carrying capacity are created on one and the same ceramic substrate ( 4 ). According to the invention, the metallization is printed multiple times in the high power range.

1 .- 8 . (canceled) 
     
     
         9 . A method for producing a metallized ceramic substrate comprising a copper multi-level metallization on a ceramic substrate, wherein the ceramic substrate comprises a ceramic selected from the group consisting of AIN and Al 2 O 3 , whereby a high power area with metallization having higher current-carrying capacity and a low power area with metallization having lower current-carrying capacity are created on the same ceramic substrate, comprising the sequential steps of:
 printing a common base metallization from a copper-based paste for the high power area and the low power area having a thickness of 20 to 50 μm with use of screen or pad printing;   reinforcing the base metallization in the high power area with multiple or several printings of a copper reinforcement paste without glass component on the base metallization using screen or stencil printing up to a total copper thickness of 300 to 500 μm;   annealing the metalized ceramic substrate with the high power area and the low power area together at 850 to 950° C. under nitrogen;   mechanical leveling of the high power areas to create an even surface having a roughness R z <5 μm to yield a metallized ceramic substrate.   
     
     
         10 . A method according to  claim 9 , whereinafter the leveling the high power area and/or the low power areas are currentlessly provided with a metallization. 
     
     
         11 . A method according to  claim 9 , wherein the ceramic substrate is processed by laser scribing before or after the printing to prepare for a later separation of the ceramic substrate into individual sub-substrates. 
     
     
         12 . A method according to  claim 9 , wherein during the leveling 100 to 150 μm are removed. 
     
     
         13 . A method according to  claim 9 , wherein the proportion of glass of the glass-containing copper-based paste is between 4 and 8%. 
     
     
         14 . A method according to  claim 9 , whereinafter the leveling the metallization of the high power area has a thickness of 180 to 220 μm. 
     
     
         15 . A metalized ceramic substrate produced by the method according to  claim 9 , wherein the thickness of the metallization is 180 to 220 μm in the high power area and 20 to 50 μm in the low power area and the adhesive strength of the metallization is above 60 N/qmm. 
     
     
         16 . A metalized ceramic substrate according to  claim 15 , wherein the edge steepness of the metallization of the high power area is 120 μm with a total copper thickness of 200 μm. 
     
     
         17 . A method according to  claim 10 , wherein the metallization comprises metal selected from the group consisting of Ni, NiP+Pd+Au, Ag and Ni+Au. 
     
     
         18 . A method according to  claim 9 , wherein the proportion of glass of the glass-containing copper-based paste is 6%.