Study on the Resistivity and Porosity of Nano Copper Powder Under Low-Temperature Sintering without Pressure

Copper powders with an average particle size of 300 nm were prepared by ascorbic acid reduction using methionine as a protective agent and further mixed with ethylene glycol to make a copper paste for pressureless low-temperature sintering. The sintering properties of copper paste were tested using SEM, XRD, TG, and four-probe tester, and the changes of resistivity and porosity at different sintering temperatures and sintering times were investigated, and the sintering behavior was analyzed by microstructure transformation. The results show that the resistivity can be as low as 17.7 µΩ-cm, the sintering temperature reaches 250℃ to form the initial sintering neck, the resistivity is around 50 µΩ-cm, which can be satisfied with the application, and the porosity increases with the increase of the sintering neck.