Liu Sushi,Yang Le,Xin Jianbo,Lv Xiaochun,Chen Yi,Liu Yang
Cu particles sintering is considered one of the most suitable connection technologies for power devices, but Cu has poor oxidation resistance and Cu oxides hinder the sintering process. In this paper, formic acid vapor is used for baking Cu paste to achieve high strength Cu–Cu joints at low temperature. The Cu–Cu joint of 33.9 MPa is obtained easily at 200 °C through baking by formic acid vapor at 130 °C for 15 min. Formic acid vapor effectively reduces the Cu oxides on the surface of the Cu particles, improving the sintering performance of the Cu paste. The effects of baking atmosphere, temperature and time on the shear strength on Cu–Cu joints are analyzed. Additionally, the mechanism of formic acid vapor in reducing the sintering temperature of Cu paste is investigated by the analysis of phase composition and thermal behavior. This work further expands the application of Cu paste in the packaging of high-power semiconductor devices.
The thermal annealing process is significant for the crystallization of perovskite films ((FAPbI 3 ) 0.9 (MAPbBr 3 ) 0.1 ). However, conventional annealing methods suffer from non-uniform heating of film samples. Herein, we report a vapor annealing method that the perovskite film was annealed in formic acid vapor, generating a uniform thermal field to control crystallization. Simultaneously, HCOOH efficiently enhances sample crystallinity, passivates defects and suppresses deprotonation, establishing an optimal physicochemical environment for perovskite growth. In addition, the electron transport layer (ETL) composed of SnO 2 and ZnO nanoparticles (NPs) demonstrates enhanced electrical conductivity and light transmittance. Methylammonium Chloride (MACl) is introduced to suppress ZnO NPs-induced deprotonation. The experimental and theoretical results manifest the mechanism of inhibiting the deprotonation reaction by MACl. The stable power conversion efficiency (PCE) of the device prepared by this method achieves 23.41 % and maintains 83 % of initial PCE during the long-term stability test.
危险品化学品经营许可证（带存储）