Design a microchannel heat sink for a 500W power electronics module with 1cm² footprint.

Design constraints: q'' = 500 W/cm², junction limit T_j < 125°C, coolant inlet 25°C. Microchannel geometry: hydraulic diameter 200-500μm balances heat transfer and pressure drop; aspect ratio 4-8 for high effectiveness. Using Churchill correlation for developing laminar flow (Re~500): with D_h=300μm, w_ch=100μm, H=800μm, 50 channels across 1cm give Nu≈8-10, h≈50,000 W/m²-K. Thermal resistance: R_total = R_conv + R_cond + R_TIM + R_spreading. At m_dot=0.01 kg/s water: ΔT_fluid=12°C, ΔT_conv=5°C, ΔT_cond(Cu base)=3°C, requiring T_base<50°C for junction compliance. Pressure drop: ΔP≈50 kPa acceptable for micropumps. Manifold design prevents flow maldistribution. Manufacturing: CNC or laser machining in copper, diffusion bonding for cover. Validate with infrared thermography on powered module.