Physical and dielectric properties of BaTiO3–fluoride–glass systems for nitrogen-fireable embedded capacitors

BaTiO3-based dielectrics containing the selective additive combinations from Pb-free glasses and fluoride compounds such as AlF3, BaF2, CaF2, LiF and ZnF2 were studied mainly for a potential N2-fireable embedded capacitor in printed circuit board with Cu metallization. The physical and dielectric properties, such as dielectric constant (k), loss tangent (tanδ) and Tc, strongly depended on the choice of additive combination. A bismuth borosilicate glass was most promising in terms of the degree of densification and dielectric constant. The samples containing LiF and ZnF2 and sintered at 950 °C looked most beneficial in that these additives produced high k of >1,200 and low tanδ of < 0.022 at room temperature regardless of sintering atmosphere. As an example, the 95BaTiO3–2LiF–3(Bi borosilicate) sample exhibited k ~ 1,340 and tanδ ~ 0.022 at room temperature when fired at 950 °C in N2.