Issue link: https://resources.mouser.com/i/1537950
C h a p t e r 3 | I n f i n e o n ' s T o p - S i d e C o o l e d ( T S C ) Q - D P A K P a c k a g e System designers must consider multiple factors: package height variations, potential PCB warpage under mounting pressure, electrical isolation requirements, and mechanical assembly constraints. Each application requires careful evaluation to optimize the thermal solution. Thermal Interface Solutions Gap Pad Approach Compressible gap pads provide one approach to address height tolerance challenges. Made of solid materials, they come in various thicknesses and thermal conductivities, providing design flexibility. Testing with a gap pad that has a thermal conductivity of 6 W/m·K, initially 1 millimeter thick and compressed to 0.5 millimeters with mechanical standoffs, showed a thermal resistance of 1 C/W. Reducing standoff height can improve thermal performance by decreasing the thermal interface thickness. However, this also increases mechanical stress on the PCB, which could cause warping and impact long-term reliability. Softer materials can withstand higher mounting pressures while reducing stress, but typically have lower thermal conductivity. Engineers must balance thermal efficiency with mechanical reliability for each specific application. Ceramic Substrate Method For applications that require electrical isolation along with good thermal performance, aluminum oxide ceramic substrates provide a practical alternative. With a thermal conductivity of around 30 W/m·K, ceramics outperform polymer-based options. Testing involved a 1.5-millimeter ceramic with 50-micrometer layers of thermal grease on both sides. Comparative measurements between Q-DPAK and TO- 247 packages using identical chip sizes and thermal stacks produced similar results, both around 1.2 C/W in thermal resistance. However, this method is limited to a few devices per heatsink, since Q-DPAK height tolerances usually require gap-filling materials thicker than the 50-micrometer grease layers needed for multi- device assemblies. Liquid Gap Filler Systems Complex assemblies with multiple devices benefit from liquid gap filler materials combined with isolation foils. The liquid material naturally conforms to height variations while providing electrical isolation. Automated dispensing equipment can apply these materials efficiently, supporting high-volume manufacturing. The additional isolation layer does impact thermal performance, but careful material selection minimizes this penalty. As with all thermal interface options, the overall stack's thermal conductivity determines the achievable thermal resistance. Implementing Topside Cool Technology Success with topside cool packages depends on understanding both their benefits and assembly needs. These packages deliver on their promise of combining thermal performance with automated assembly, but achieving the best results requires careful attention to thermal interface design. Infineon offers comprehensive design tools and resources to support implementation, helping designers select thermal interfaces and optimize assembly. When properly implemented, topside cool Q-DPAK packages enable power electronic systems that are both thermally efficient and cost-effective to produce, finally addressing the industry's longstanding trade-off between performance and manufacturing efficiency. 17 Enabling Compact, Efficient Designs with High Voltage CoolSiC™ Discretes