Preparation Of Silver Nanoparticle Paste And Its Application For Low-Temperature Sintering Interconnection

With the development of the semiconductor industry,the third generation of wide bandgap semiconductor materials represented by Si C and GaN have attracted great attention in power device applications in recent years.This puts higher requirements on the high-temperature service and heat dissipation performance of packaging materials for high-power density devices.For traditional chip interconnect materials such as conductive paste and alloy solder,which are unable to meet the needs of high-temperature service.Silver nanoparticle paste with low-temperature sintering and high-temperature service properties is one of the most potential replacement for traditional package interconnect materials.The sintering temperature of silver nanoparticle paste is related to the size of silver nanoparticles and the decomposition temperature of organisms.At present,the development of silver nanoparticle pastes with low-temperature sintering and high-temperature service still faces the following problems:the technology for preparing silver nanoparticles with a particle size of less than 50 nm faces great challenges,and the organic system of silver nanoparticle paste is difficult to completely decompose at low-temperatures,and the sintering performance of the silver nanoparticle paste needs to be improved.In view of the above problems of package interconnection,this paper studied the preparation of silver nanoparticles with particle size less than 50 nm,screened the organic system used to prepare silver nanoparticle pastes,and then analyzed the sintering quality and performance of silver nanoparticle pastes.The connection process of package interconnection and the relationship between joint strength and microstructure were studied.The main research contents of this paper are as follows:1. Controllable preparation of silver nanoparticles.The reduction of AgNO₃by chemical reduction was carried out,and the influence of different factors on the particle size and morphology of the silver nanoparticles was investigated to prepare silver nanoparticles with a particle size of less than 50 nm.The morphology and purity of silver nanoparticles were characterized by SEM and XRD instruments.Nano Measurer software was used to measure the particle size and distribution of silver nanoparticles.It was found that when the concentration of AgNO₃was 0.1 mol/L and the concentration of PVP was 0.15 mol/L,silver nanoparticles with a particle size of 20-40 nm could be prepared.2. Preparation of silver nanoparticle paste and investigation of its low-temperature sintering properties.The prepared silver nanoparticles are used and the organic composition of the silver nanoparticle paste was determined to preparing a silver nanoparticle paste having a suitable viscosity and a certain fluidity.By investigating the influence of different sintering conditions on the quality of the silver nanoparticle paste sintered body,it was found that when the content of the binder was about 10 wt%,the sintering temperature was 250?,and the holding time was 30 min,the sintered body of silver nanoparticler paste has a porosity of only 0.1%,a grain size of 0.4-0.7?m,a thermal conductivity of 161.45 W/m·K,and a resistivity as low as 8.73??·cm.3. Study of sintering process of silver nanoparticler paste and joint reliability.The sandwich-like package interconnect structure was used to investigate the bonding properties of silver nanoparticler paste package interconnects,and the effects of different external factors on the shear strength of interconnected joints were investigated.It was found that when the content of the binder was about 10 wt%,the sintering temperature was 250?,and the holding time was 30 min,the shear strength of the interconnected joint reached 24.1 MPa and the organic residue was about 1 wt%.