In this study, we present the implementation of flip-chip GaN (Gallium Nitride) power devices in a double-side ceramic cooling packaging structure, designed for use in power devices and modules such as PM (Power Modules) and IPM (Intelligent Power Modules). This packaging approach is engineered to maximize thermal dissipation and enhance electrical performance, making it highly suitable for high-power and high-frequency applications.
1. Key benefits of the double-side Cooling fliP-chip power GaN ceramic QFN/DFN architecture: 1.1. Enhanced thermal management and power density. 1.2. Reduced electrical path lengths, resulting in lower parasitic effects and improved high-frequency operation. 1.3. Higher current handling capability and improved EMI performance
2. Flip-Chip GaN with Double-Side Cooling Design The flip-chip GaN die is mounted upside-down on a ceramic substrate featuring fine line/space (100 µm / 100 µm) and thick copper patterns (150–300 µm). For top-side heat dissipation, a 3D copper-structured ceramic clip is mounted directly on the GaN die. This clip may include a two-layer copper stack, for example: 100 µm (1st Cu) + 300 µm (2nd Cu).
3. Key structural considerations include: 3.1 Both the ceramic substrate and ceramic clip are inorganic and organic-free along the thermal path, ensuring reliable heat flow. This design allows for thermal and electrical separation in both top and bottom paths. 3.2 Substrates are fabricated from high thermal conductivity ceramics such as AlN (Aluminum Nitride) or Si₃N₄ (Silicon Nitride) with metallized surfaces to support electrical connections and thermal dissipation.
4. Ceramic QFN/DFN Design Highlights The bottom-side ceramic substrate enables efficient heat removal through the PCB, while also maintaining electrical isolation. The top-side ceramic 3D clip functions as a heat spreader, facilitating heat transfer to a top-mounted heatsink. The use of purely inorganic materials in the thermal path improves reliability under high-power cycling.
Following are the packaging solution considerations: Feature Ceramic QFN/DFN Standard QFN/DFN Substrate AlN, Si₃N₄ (High thermal conductivity) FR4, BT resin Power GaN Clip chip/Wire bond available Wire bond Thermal Conductivity 170–230 W/m·K ~1–20 (With copper vias W/m·K) Die Attach Sintered Ag Solder SnAgCu Top Cooling Support Direct attached ceramic spreader Ceramic with isolation polymer Reliability Excellent Moderate
5. Summary of Packaging Technologies in This Study 5.1 Ceramic substrate with fine line/space (100 µm/100 µm) and thick Cu (150–300 µm) patterns for flip-chip GaN devices. 5.2 Thermal and electrical separation design in the ceramic substrate for enhanced bottom-side cooling in QFN/DFN packages. 5.3 3D copper-structured ceramic clip, acting as a top-side heat spreader. 5.4 Sintered silver process for high-reliability flip-chip die attachment. 5.5 Ceramic QFN/DFN package solutions tailored for PM and IPM applications, with a focus on thermal performance, reliability, and scalability for production.
