Metallisation of Laser-drilled Holes in 96% Alumina by Screen Printing Mixed-bonded Pd Ag: Printing Technology and Reliability of Metallisation

Hybrid manufacturers are uncertain as to whether laser-drilled holes on 96% alumina are suitable for mixed-bonded thick film conductor metallisation, or whether they require further treatment before metallisation if reliable circuitry is to be produced. Moreover, although the metallisation of holes on ceramic through the use of screen printed thick films is fairly common in the hybrid industry, this paper shows that published information on this topic is scant, at times contradictory, and, because of proprietary constraints, generally of little use. The authors report on an extensive study in which both as-laser-drilled holes and thermally-treated laser-drilled holes are metallised using a mixed bonded Pd-Ag conductor paste. Both encapsulated and non-encapsulated metallised holes are then subjected to various accelerated life tests, followed by 'power-up' tests to the extreme of circuit destruction. An account is also given of a printing set-up which allows volume production of printed through-holes without the need for special skill or attention on the part of the printing operator.