Multilayer capacitors with bismuth copper tantalate dielectric fabricated in LTCC technology

Abstract

Purpose

The work was aimed at preparation of green tapes based on a new material Bi_2/3CuTa₄O₁₂, to achieve spontaneously formation of an internal barrier layer capacitor (IBLC), fabrication of multilayer elements using low temperature cofired ceramics (LTCC) technology and their characterization.

Design/methodology/approach

The study focused on tape casting, lamination and co-sintering procedures and dielectric properties of Bi_2/3CuTa₄O₁₂ multilayer capacitors. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) studies of the ceramic elements were performed. Impedance spectroscopy was used for characterization of dielectric properties in the frequency range of 0.1 Hz to −2 MHz and in the temperature range from −55 to 400°C. DC conductivity was investigated in the temperature range 20 to 740°C.

Findings

SEM observations revealed a good compatibility of the applied commercial Pt paste with the ceramic layers. The EDS microanalysis showed a higher content of oxygen at grain boundaries. The dominant dielectric response, which was recorded in the low frequency range and at temperatures above 0°C, was attributed to grain boundaries. The dielectric response at low temperatures and/or high frequencies was related to grains. The fabricated multilayer capacitors based on Bi_2/3CuTa₄O₁₂ exhibited a high specific capacitance.

Originality/value

A new material Bi_2/3CuTa₄O₁₂ was applied for preparation of green ceramic tapes and utilized for fabrication of multilayer ceramic capacitors using the LTCC technology. This material belongs to the group of high permittivity nonferroelectric compounds with a complex perovskite structure of CaCu₃Ti₄O₁₂, that causes the spontaneously formation of IBLCs.

Citation

Szwagierczak, D., Kulawik, J., Synkiewicz, B. and Skwarek, A. (2016), "Multilayer capacitors with bismuth copper tantalate dielectric fabricated in LTCC technology", Microelectronics International, Vol. 33 No. 3, pp. 118-123. https://doi.org/10.1108/MI-02-2016-0016