A Study Of Interconnection Reliability For Low-temperature Sintered Nano-silver Paste

Traditional chip level interconnection materials showed lots of weakness with the development trend of microelectronic packaging technology. In order to meet the need of high-temperature packaging of wide-band gap semiconductor in electronic industry, low-temperature sintered nano-silver as a novel semiconductor device-metallized substrate interconnected material was studied in this paper. One big difference between this material and traditional solder alloy is that the silver paste connects substrate and chips using a sintering process which processed at a lower temperature than melting point of nano-silver. In this paper, a series of reliability tests were designed to investigate the interconnection reliability of low-temperature sintered nano-silver paste. And dynamic mechanical properties of this interconnection material were also studied.Based on the traditional sintering theory and the special characters of nanoscale powder, a low-temperature sintering technology was employed in the preparation for sintered nano-silver die-attachment. Firstly, force-life curve and fatigue properties of this interconnection material were gained through the shear fatigue tests under different loading conditions. At the same time, one phenomenon that larger interconnect area would cause poorer interconnect quality had been found. The changes of the shear strength and nano-silver joints microstructures by using Scan Electronic Microscope (SEM) and optical microscope were observed with the different interconnection areas investigated in order to explain the mechanism. Besides, the thermomechanical reliability of sintered nano-silver die-attachment was studied through thermal cycling test, including shear strengths and microstructures with cavity ratios of nano-silver joints. Finally, low-temperature sintered nano-silver films were prepared for Dynamic Mechanical Analyzer (DMA) test. Basic dynamic mechanical properties of this interconnected material at working temperature were investigated, such as the stress-strain curves at different temperatures and the dynamic scan curves of the elastic modulus.