Achieving high adhesion and low‐temperature sintering for multilayer ceramic capacitors by tunning the structure of SrO‐ZnO‐B₂O₃‐SiO₂ glass

Abstract

Multilayer ceramic capacitors (MLCCs) are one of the most widely used and rapidly advancing chip electronic components for high frequency and high integration applications. It is challenging to develop low‐temperature sintering copper pastes for fabricating MLCC terminal electrodes with high adhesion and reliability. Herein, our work demonstrates a novel SrO‐ZnO‐B2O3‐SiO2 glass as a fluxing agent for lowering the sintering temperature of copper paste to enhance adhesion and reliability for MLCCs. It is found that Sr ions as glass modifiers can not only effectively lower the sintering temperature of the glass to 775°C, but also contribute a promotion to the thermal expansion coefficient, which originates from the conversion of the stable [ZnO4] network into a loose [ZnO6] network. The copper paste containing 12.5 SrO‐32.5 ZnO‐40 B2O3‐15 SiO2 (mol.%) was applied for practical terminal electrode sintering at 775°C, exhibiting a dense surface without cracks, integrated cross‐sectional morphology, and high adhesion force (10.2 LB). Furthermore, MLCCs showed lower square resistance (5.65 mΩ/sq), higher reliability in reflow soldering testing (265°C,110 cm/min), and resistance to soldering heat testing (235 ± 5°C, 30 s). Therefore, this work blazes the trail of preparing a novel low‐melting glass for terminal electrode applicable copper paste for the practical MLCCs industry.