Thermal conductivity optimization of aluminum powder metallurgical heat dissipation substrates in the field of electronic packaging: porosity and interface thermal resistance control

In the field of electronic packaging, heat dissipation performance directly affects the reliability and service life of electronic devices. Aluminum powder metallurgical heat dissipation substrates are widely used due to their low cost and good processability, and thermal conductivity is a key indicator to measure their heat dissipation ability. By controlling porosity and interface thermal resistance, thermal conductivity can be effectively optimized.

The porosity has a significant impact on the thermal conductivity of aluminum powder metallurgical heat dissipation substrates. The presence of pores can hinder the conduction of heat inside the substrate and reduce thermal conductivity. On the one hand, with the increase of porosity, the effective aluminum matrix area for conducting heat in the substrate decreases, and the heat transfer path is blocked, resulting in an increase in thermal resistance and a decrease in thermal conductivity. On the other hand, the shape, size, and distribution of pores also affect thermal conductivity. Irregular and interconnected pores will form more tortuous heat flow channels, increasing the difficulty of heat conduction; The negative impact of uniformly distributed small closed pores on thermal conductivity is relatively small. Therefore, during the preparation process, it is necessary to strictly control the porosity. By optimizing the particle size, shape, and pressing process parameters of aluminum powder, such as pressing pressure, holding time, etc., the generation of pores can be reduced, porosity can be lowered, and the thermal conductivity of the substrate can be improved.

The interface thermal resistance is also an important factor affecting the thermal conductivity of aluminum powder metallurgical heat dissipation substrates. In electronic packaging structures, there is an interface between the heat dissipation substrate and components such as chips and heat sinks, and the thermal conductivity efficiency at the interface determines the overall heat dissipation performance. The interface thermal resistance mainly comes from the differences in physical properties of materials on both sides of the interface, surface roughness, and possible gaps or pollutants between the interfaces. To reduce interface thermal resistance, various methods can be used. Firstly, fine machining is carried out on the surface of the substrate and the components in contact with it to reduce surface roughness, enabling better adhesion between the two and reducing heat flow obstruction caused by uneven surfaces. Secondly, high thermal conductivity interface materials such as thermal grease and thermal pads are introduced at the interface, which can fill the small gaps between the interfaces, improve the interface contact condition, and reduce the interface thermal resistance. In addition, through surface treatment techniques such as chemical plating, electroplating, etc., a metal coating with a thermal expansion coefficient that matches the adjacent material and good thermal conductivity can be formed on the substrate surface, which can effectively reduce the interfacial thermal resistance.

In summary, in the field of electronic packaging, by precisely controlling the porosity of aluminum powder metallurgical heat dissipation substrates, optimizing the pressing process, and using appropriate surface treatment and interface materials to reduce interface thermal resistance, the thermal conductivity of heat dissipation substrates can be significantly improved, meeting the demand for efficient heat dissipation in electronic devices and ensuring stable operation of electronic devices.