Manufacturing low thermal resistance/low cost composite radiator through cold spray process
Electronic equipment generates heat during operation, which leads to a decrease in performance and reliability. IC components with large thermal power consumption usually use a heat sink to conduct heat to prevent the junction temperature from exceeding the maximum allowable limit.
Installing a heat sink on a silicon-based semiconductor chip and finally dissipating the heat of the chip through air or liquid is a common cooling method for electronic devices. These radiators are usually made of copper or aluminum alone, or a combination of copper and aluminum.
Copper radiators are expensive, but aluminum radiators have insufficient thermal conductivity
The thermal conductivity of copper is greater than that of aluminum, and the heat dissipation capacity per unit volume is better than that of aluminum. Excluding the influence of weight and cost, copper is the preferred material for heat sinks. Aluminum has low thermal conductivity, so aluminum radiators cannot dissipate heat fast enough, and require larger surface area and higher fins. In many compact applications, especially in the pursuit of high power density systems, aluminum radiators are not best choice.
Why do we need a copper-aluminum composite radiator?
The radiator includes a base that contacts the heat source chip, and fins connected above the base by manufacturing methods such as stamping welding, extrusion, gear cutting, and shoveling. The base contacts the chip, absorbs the heat of the chip and conducts it to the fins. The fins try to increase the surface area, speed up the air heat exchange efficiency, and finally take away the heat of the chip.
High-power electronic equipment often heats up the chip very quickly. If the heat sink is an aluminum base, the heat transfer speed of the base may not be enough to quickly diffuse the heat to the surface of the fin, resulting in an increase in the thermal resistance of the heat sink and cooling Insufficient performance.
The entire or partial area of the aluminum radiator base can be replaced with a copper material with better thermal conductivity to solve the problem of insufficient heat diffusion speed. Such a composite heat sink base uses copper to quickly conduct heat from the chip, and the fins are still aluminum, which can achieve both rapid heat diffusion and cost-effectiveness.
Disadvantages of traditional technology to manufacture composite radiators
Adding copper to the aluminum radiator base to improve heat conduction, the usual methods are copper embedded and soldered copper, but they inevitably introduce some new defects:
Copper embedding: first remove the aluminum material at the copper embedding position on the base by cutting chips, and then apply thermal interface material on the bottom of the copper embedding area, then the copper block is embedded in the aluminum matrix of the base under a tight fit, and finally the chips are polished again. A copper-embedded base with a smooth and flat surface is obtained. This brings about two problems. The thermal interface material of the copper-aluminum interface brings additional thermal resistance, the mosaic interface is in a long-term thermal expansion mismatch and causes looseness, there is a risk of sinking of the copper embedded, and the risk of a sharp drop in the performance of the heat sink.
Welding copper: Aluminum is usually used for direct bonding of copper or brazing, and the copper material is combined on the base. It is very difficult to directly bond copper with aluminum, the process cost is high, and the economic benefit is low; brazing must introduce welding materials, and there are problems such as interfacial corrosion, inconsistent thermal conductivity of the interface, and mismatched thermal expansion.
