Research Information System
Journal of the Korean Ceramic Society, vol.59, no.3, pp.383-392, 2022 (SCI-Expanded)
© 2022, The Korean Ceramic Society.LTCC applications require densification at temperatures lower than 950 °C to allow co-firing with metal electrodes, lower dielectric constant to increase signal transmission speed, a thermal expansion coefficient matched to Si for reliability and higher thermal conductivity to dissipate heat. For this purpose, (SiO2–Al2O3–CaO)-based glass (50–60 wt%)/ceramic (Al2O3 or mullite) composites with nano-hBN (0–10 wt%) addition were investigated. Al2O3 was replaced by mullite to decrease dielectric constant and to match thermal expansion coefficient to Si, and hBN was incorporated to increase thermal conductivity and to decrease dielectric constant. Densification at temperatures ≤ 900 °C was easily achieved for all compositions due to viscous sintering of the glass matrix. hBN did not react chemically with crystalline and amorphous phases, which effectively decreased dielectric constant and increased thermal conductivity. Hence, both mullite and nano-hBN strongly improved dielectric and thermal properties required for the LTCC applications. Dense mullite/glass (55 wt%) base composite with 10 wt% hBN addition was successfully engineered and had comparable dielectric and thermal properties (i.e., 2.3 gcm−3 after sintering at 900 °C, dielectric constant (loss) = 5.13 (0.003) at 5 MHz, thermal conductivity = 1.91 Wm−1 K−1 at 25 °C, and thermal expansion coefficient for the base composite = 4.75 ppm°C−1) with respect to the commercial LTCC products. Graphical abstract: [Figure not available: see fulltext.]