Sintering, Microstructure, and Dielectric Properties of Copper Borates for High Frequency LTCC Applications.

Dorota Szwagierczak,Norbert Pałka,Jan Kulawik,Beata Synkiewicz-Musialska

doi:10.3390/ma14144017

Abstract

New ceramic materials based on two copper borates, CuB2O4 and Cu3B2O6, were prepared via solid state synthesis and sintering, and characterized as promising candidates for low dielectric permittivity substrates for very high frequency circuits. The sintering behavior, composition, microstructure, and dielectric properties of the ceramics were investigated using a heating microscope, X-ray diffractometry, scanning electron microscopy, energy dispersive spectroscopy, and terahertz time domain spectroscopy. The studies revealed a low dielectric permittivity of 5.1–6.7 and low dielectric loss in the frequency range 0.14–0.7 THz. The copper borate-based materials, owing to a low sintering temperature of 900–960 °C, are suitable for LTCC (low temperature cofired ceramics) applications.

Highlights

For the compositions prepared as CuB2 O4 –Cu3 B2 O6 mixtures with a 5% CuBi2 O4 addition, the XRD analysis revealed two main crystalline copper borate phases, but additional crystalline phases were not detected (Figure 1d)
New ceramics based on two copper borates, CuB2 O4 and Cu3 B2 O6, were successfully prepared via solid state synthesis and sintering processes
All authors have read and agreed to the published version of the manuscript

Summary

Introduction

Modern high frequency communication systems create demand for new substrate materials with specific dielectric characteristics comprising a low dielectric permittivity, a low dielectric loss, and a low temperature coefficient of dielectric permittivity. Such dielectric properties of a substrate for microwave and mm-wave circuits improve the signal speed and quality, selectivity, and temperature stability of the operating frequency [1,2,3,4,5]. Tungstates, and phosphates, some borates are good candidates for new materials with a low sintering temperature [13,14,15,16,17,18,19,20,21,22,23,24]

Methods

Results

Conclusion