Premium
Microstructural Characterization of Cofired Tungsten‐Metallized High‐Alumina Electronic Substrates
Author(s) -
Behrens Gesa,
Heuer Arthur H.
Publication year - 1992
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1992.tb05510.x
Subject(s) - materials science , devitrification , anorthite , sintering , aluminate , spinel , metallurgy , tungsten , ceramic , composite material , mineralogy , chemical engineering , crystallization , cement , chemistry , engineering
Microstructural characterization of a high‐Al 2 O 3 substrate containing cofired thick‐film tungsten metallization, with particular emphasis on the metal/ceramic interface, was conducted. The substrate contained tabular Al 2 O 3 grains surrounded by a continuous calcium magnesium aluminum silicate glass containing particles of monoclinic ZrO 2 and reduced rutile (TiO 2‐ x ). The metal/ceramic adhesion was caused by mechanical interlocking between the W and Al 2 O 3 grains by the glass phase which penetrated the porous W layers during sintering; there was no interfacial reaction or diffusion zone. The mechanical properties of the W metallization did not limit interfacial strength. Heat treatments of the substrate at 1400 K in air and under vacuum resulted in the devitrification of the intergranular glass. The most abundant devitrification product was anorthite (CaAl 2 Si 2 O 8 ), accompanied by magnesium aluminate titanate, magnesium aluminate spinel, α‐cristobalite (SiO 2 ), and α‐cordierite (Mg 2 Al 4 Si 5 O 18 ). In addition, small rutile particles precipitated within the Al 2 O 3 grains.