Aluminium transfers heat well, but poor contact can erase much of that advantage. In practical assemblies, microscopic gaps trap air between the heat spreader and its adjacent component. Air is a poor thermal path. Improve the interface before increasing fin size. Measure both surfaces for flatness, burrs, and contamination. Even a thin oxide film or machining chip can raise contact resistance.
Use a thermal interface material only when it fills real surface gaps. Apply the thinnest continuous layer supported by the material data and assembly tolerance. Excess compound may behave like insulation. Clamping pressure must remain even across the contact area. Too little pressure leaves voids, while too much can distort a thin aluminium cover. Controlled torque, suitable washers, and a stiff mounting pattern improve repeatability. Clean with approved methods, then assemble without touching the prepared surface.
In practical testing, record interface temperature, heat input, and ambient conditions. Thermal camera readings can mislead when surface emissivity is not corrected. A useful check compares the temperature drop across the joint before and after refinement. One workshop trial showed a cooler housing, but the result changed after repeated heating cycles. The initial measurement was too optimistic. Recheck after vibration, thermal cycling, and service-like tightening. Contact quality is not permanent. Surface finish, mounting distortion, and interface aging deserve attention during design reviews.