Microwave dielectric properties of SnO‐SnF₂‐P₂O₅ glass and its composite with alumina for ULTCC applications

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p>Ultralow‐temperature sinterable alumina‐45SnF₂:25SnO:30P₂O₅ glass (Al₂O₃‐SSP glass) composite has been developed for microelectronic applications. The 45SnF₂:25SnO:30P₂O₅ glass prepared by melt quenching from 450°C has a low Tg of about 93°C. The SSP glass has εᵣ and tanδ of 20 and 0.007, respectively, at 1 MHz. In the microwave frequency range, it has εᵣ=16 and Qᵤ × f=990 GHz with τf=−290 ppm/°C at 6.2 GHz with coefficient of thermal expansion (CTE) value of 17.8 ppm/°C. A 30 wt.% Al₂O₃‐70 wt.% SSP composite was prepared by sintering at different temperatures from 150°C to 400°C. The crystalline phases and dielectric properties vary with sintering temperature. The alumina‐SSP composite sintered at 200°C has εᵣ=5.41 with a tanδ of 0.01 (1 MHz) and at microwave frequencies it has εᵣ=5.20 at 11 GHz with Qᵤ × f=5500 GHz with temperature coefficient of resonant frequency (τf)=−18 ppm/°C. The CTE and room‐temperature thermal conductivity of the composite sintered at 200°C are 8.7 ppm/°C and 0.47 W/m/K, respectively. The new composite has a low sintering temperature and is a possible candidate for ultralow‐temperature cofired ceramics applications.</p></div>