Bonding of Cu wires by solid state sintering of Ag nanoparticles at low temperatures
- PDF / 218,860 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 22 Downloads / 233 Views
1207-N07-36
Bonding of Cu wires by solid state sintering of Ag nanoparticles at low temperatures Hani Alarifi, Anming Hu, Mustafa Yavuz, Y. Norman Zhou Centre of Advanced Materials for Joining, Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
ABSTRACT Solid state sintering of Ag nanoparticles was used to bond Cu wires to Cu foils at temperatures less than 250oC. The Ag nanoparticles are coated with an organic shell to prevent sintering at room temperature. After annealing the nanoparticles at 200oC, the decomposition of the organic shell was confirmed using TGA and Raman spectroscopy. The joint strength was measured by tensile shear tests, which shows that the joint strength increases as the bonding temperature increases. Metallic bond between Ag nanoparticles and Cu was achieved with no contamination. Bonds formed by our method, was confirmed to withstand temperatures higher than the bonding temperatures.
INTRODUCTION Developing bonding methods at low temperature is important for polymer and flexible electronic. On the other hand, decreasing the bonding temperatures for electronics packaging and interconnection leads to cost reduction. It’s desirable that these joints can bear high temperature environment such as those around car engines. Thus, forming joints at low temperature that can operate at higher temperature environment is very promising. Sintering of nanoparticles occurs at temperatures much lower than microparticles due to their high surface to volume ratio. Thus, it became possible to bond metals at low temperature by sintering of nanoparticles. Ag nanoparticles coated with organic shells were used to bond metals at temperature as low as 250oC [1-6]. These bonds were formed by sintering of nanoparticles, which starts at the temperature were the organic shell decomposes. Ag nanoparticles were observed to sinter at temperatures as low as 150oC in ambient air [7]. Sintering of Ag nanoparticles was also achieved at room temperature by removing the dispersant using methanol [8,9]. Sintering of Ag nanoparticles on Cu single crystal substrate was observed at 100oC [10]. In this work, we use low temperature sintering of Ag nanoparticles to bond copper wires to copper foils. The nanoparticles concentration in water was increased by centrifugal action to enable us to develop Ag naoparticles paste. The used Ag nanoparticles have very thin organic shell which allows sintering of nanoparticles to occur around 100oC and the bond with copper to form at 160oC. These bonds formed with copper do not degrade when the joints are tested at higher temperature environments. Metallic bond between sintered Ag nanoparticles and Cu was achieved with no contamination.
EXPERIMENTAL Ag nanoparticles with an average size of 50 nm and size distribution in a range of 20 nm to 100 nm are used in the sintering and bonding studies. The Ag nanoparticles are prepared by reduction action of AgNO3 using sodium citrate dehydrate Na3C6H5O7.2H2O. The conc
Data Loading...
