Large-scale synthesis of Ag nanoparticles by polyol process for low temperature bonding application

Lead is a toxic element which usually brings harm to natural resources and human health. The use of Pb-containing solder alloys are forbidden to be employed in electronic packaging, which led to the great efforts to the investigation and implementation of lead-free bonding materials. The novel low temperature sintering bonding using metal nanoparticles is a promising technique for lead free bonding method used in electronic packaging industry. In this article, a large scale chemical reduction method to synthesize silver nanoparticles (Ag NPs) for this low temperature bonding application was put forward. The obtained Ag NPs were confirmed by XRD to be crystalline silver with a face-centered cubic (fee) structure. We observed monodisperse spherical Ag NPs with a diameter range of 35 ± 15 nm. The influence of reaction parameters on the resulting particle size and its distribution is investigated. Robust joints were formed using the Ag NPs as the bonding materials at the low bonding temperature. The shear strengths of joints reach about 49.93 MPa at low temperature of 250 °C. The results show that the Ag NPs synthesized by this large scale chemical reduction method are suitable to be used as low temperature lead bonding material in electronic packaging industry.