Study of tungsten metallization surface states for multilayer ceramic

Ceramics are widely used in high reliable microelectronic packaging for their good electricity, thermal, mechanical characteristics and dimension stability. Metallization of multilayer ceramic is one of the key techniques affecting the packaging quality and reliability. Metallization conductor should have appropriate resistivity, compact structure and can be co-fired with ceramic etc. There are many reports about Mo-Mn metallization technology, but rare about multilayer ceramic tungsten metallization especially about its surface states. Surface states of metallization affect the adhesive strength, airtightness character and reliability of nickel-plating directly. The tungsten metallization surface state of three pastes was analyzed with SEM and EDS. Study the influence of viscosity, printing parameters, conductor thickness, sintering cycle etc. In order to analyze the effects of microstructure to the performance and surface quality of products, metallization surface states of every product was observed. The experiments indicated that two of the three pastes have alumina grains in the metallization surface after printing. According to the printing parameters, the printing process influences the surface state but doesn´t have obvious effect on grains. The amounts of grains decrease with the increase of conductor´s thickness. After fired, the ceramic grains in the conductor grow up apparently. The results indicated that adhesion of the metallization can be controlled by adjusting the sintering temperature and soaking time. For the ceramic grains exists in the nickel layer, the nickel layer has many impurities which affect the roughness of nickel-plating apparently. In a word, control metallization state and optimize process parameters are very important to the quality and reliability of products.