Conductive Paste for Multilayer Ceramic Capacitor Manufacturing
The conductive paste used to form the inner electrode layer is mainly made from nickel slurry with an organic “vehicle”. Typical contaminants found in Ni paste also include large particles and agglomerations, and contaminants from raw materials (oversized and agglomerated Ni slurry).
The nickel inner-electrode requires a sufficient number of nickel particles lined up in order to achieve proper current flow. The presence of oversized nickel particles can prevent such particle line-up and negatively impact electrical performance.
Nickel slurry is made from Ni powder, additives and aliphatic (or aromatic) hydrocarbons. One especially suitable additive is the same BT powder, 20 nm - 30 nm, used for making the dielectric. The vehicle is comprised of a cellulosic binder, terpineol and an aliphatic (or aromatic) hydrocarbon.
Formulation of the nickel conductive paste is completed upon mixture of the nickel slurry and the vehicle.
Filtration of Ni conductive paste is particularly challenging due to its high viscosity (10,000 to 30,000 cP and 50 wt % to 60 wt %.) Pall Corporation has successfully implemented proprietary filtration technologies for such high viscosity applications.
Filtration Products for Conductive PastePall Corporation’s Ultipor® GF-HV filter contains an additional strong supporting layer to address the high viscosity demands of this application.