With the rapid development of semiconductor devices in the direction of high power, high frequency and high integration, the heat generated during the operation of chips is increasing, which puts forward higher requirements for the thermal management performance of packaging materials. Among many packaging materials, molybdenum-copper alloy (Mo-Cu alloy) has become an ideal candidate material for high-end power devices and semiconductor chip packaging due to its excellent thermal performance and thermal expansion matching.
Mo-Cu alloy is a metal matrix composite with molybdenum (Mo) as the reinforcing phase and copper (Cu) as the continuous phase, which has the high melting point and low thermal expansion coefficient of molybdenum and the high thermal conductivity and high electrical conductivity of copper. The molybdenum-copper alloy prepared by powder metallurgy process has a low density and dense structure, and can adjust the copper content (generally 1535 wt%) according to the actual demand, so as to control the coefficient of thermal expansion (CTE) in the range of 69 ×10??/K. This value is close to that of common semiconductor materials such as silicon (Si, about 3~4 ×10??/K) and gallium arsenide (GaAs, about 6 ×10??/K), which helps to achieve the matching of thermal expansion between the chip and the carrier, significantly reduce the thermal stress, and improve the stability and service life of the device.
In addition, Mo-Cu alloys have extremely high thermal conductivity, generally between 180~220 W/m·K, which is much higher than traditional ceramic-based packaging materials (such as Al?O? or AlN) and iron-nickel alloys (Kovar）。 This makes it play a key role in chip heat dissipation, especially in packages of devices with demanding heat dissipation requirements, such as IGBTs, lasers, and RF power amplifiers. Molybdenum copper material can be used as a heat sink, base plate or intermediate heat diffusion layer of the chip, effectively conducting the heat generated during the operation of the chip to the heat dissipation system, so as to avoid overheating damage.
In terms of processing adaptability, Mo-Cu alloys are also superior to other superalloys. Thanks to the presence of the copper phase, the material has good machinability and is suitable for conventional processes such as CNC turning, milling, grinding and surface coating, which can meet the manufacturing requirements of high-precision and complex structural parts, and is convenient for integrated design and packaging applications of miniaturized devices.
However, molybdenum-copper alloys also present certain challenges in practical applications. For example, it is easy to oxidize on the surface in a high-temperature oxidation environment and needs to be used under vacuum or inert gas protection; At the same time, the presence of copper leads to a lower melting point, limiting its long-term use in extremely high temperature environments. However, through further material modification (such as adding microalloying elements such as Re and La) and surface protection measures, its high-temperature oxidation resistance and structural stability can be improved to a certain extent.
