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.
Electrically conductive adhesives (ECAs) are one of the low temperature bonding materials. It can be used to replace toxic Sn-Pb solder. The key issue for the application of ECAs is how to improve their electrical properties. In the present study, we develop an effective method to promote the electrical properties of ECAs by addition of polyaniline (PANI) nanoparticles. PANIs were synthesized via a facile one-step chemical oxidative polymerization method. After adding 0.5 wt% PANI nanoparticles, the conductivity of ECAs increased dramatically by an order of magnitude. The bulk resistivity of 8.8 × 10−5Ω·cm is achieved for 65 wt% silver fillers with 0.5 wt% PANIs loaded ECAs. Besides, this improvement has no negative effect on the shear strength and the aging life of ECAs. Moreover, the use of PANIs not only lowers the percolation threshold of ECAs, but also reduces the cost and improves the bonding reliability. Finally, PANIs enhanced ECAs patterns were successfully printed by a stencil printing method, which proved their potential applications in replacing conventional solder pastes and printing functional circuits.Keywords:Electrically conductive adhesive;polyaniline;electrical property and reliability;low-temperature bonding;printable circuits
危险品化学品经营许可证（带存储）