Metallisation of Laserdrilled Holes in 96 Alumina by Screen Printing Mixedbonded PdAg Printing Technology and Reliability of Metallisation

Hybrid manufacturers are uncertain as to whether laserdrilled holes on 96 alumina are suitable for mixedbonded 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 aslaserdrilled holes and thermallytreated laserdrilled holes are metallised using a mixed bonded PdAg conductor paste. Both encapsulated and nonencapsulated metallised holes are then subjected to various accelerated life tests, followed by powerup tests to the extreme of circuit destruction. An account is also given of a printing setup which allows volume production of printed throughholes without the need for special skill or attention on the part of the printing operator.