Integrated cold sintering of ceramic circuit substrate for power device packaging

The Al₂O₃ ceramic substrate exhibits significant potential in advanced packaging due to its superior comprehensive properties but is hindered by complex technology (separate processing of ceramic sheets and circuits), stringent processing conditions (>1000 °C), and high thermal expansion coefficient, thus limiting its application in high heat dissipation devices. The cold sintering process (CSP), an advanced method for processing ceramic sheets, offers notable advantages in technology, costing, and flexibility, but still encounters restrictions regarding the thermal properties of the ceramic sheet, and the feasibility of concurrently preparing the ceramic sheets and circuits remains unexamined. Therefore, a straightforward and economical method for creating integrated ceramic circuit substrates based on CSP was proposed herein. The Al₂O₃ ceramic sheets and circuit layer metal were directly combined by molding copper foil and Al₂O₃ slurry together under a pressure of 300 MPa, the circuits were subsequently refined through pattern etching to create the Al₂O₃ CSP ceramic substrate, and the performance of the novel substrate in white light-emitting diode (WLED) packaging was validated. The exceptional CSP method significantly enhances the preparation efficiency and overall performance of the Al₂O₃ ceramic substrate. The Al₂O₃ CSP ceramic sheets exhibit minimal mass loss of 1.47 %, a high densification of 3.0263 g/cm³, a low thermal expansion coefficient of 1.286 × 10⁻⁵/°C, and superb bonding strength with copper foil (12.0 MPa). The Al₂O₃ CSP ceramic substrate ensures stable optical and thermal performance of the WLED, demonstrating its potential as a strategy for power device packaging and broadening the fabrication methods and application scope of the ceramic substrate.