Study of Electromigration of Nano Silver Paste by Direct Writing with Needle Type Dispenser

• Main Authors: Po-ChengSu, 蘇柏丞
• Other Authors: In-gann Chen
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/9vamxb

碩士 === 國立成功大學 === 材料科學及工程學系 === 106 === The relationship between porosity and electromigration can be discussed by fabricating nano-scale structures. Electromigration usually occurs during the accumulation of atoms accompanied by protrusions or hillocks at the anode and during the depletion of atoms accompanied by voids or an open circuit at the cathode. However, we show that electromigration occurs over the entire stripe surface, not just at the anode or cathode. Paste PM03 was the nano-silver paste used in this research. After using Needle Type Dispenser to direct write paste PM03 on the silicon substrate, a hot press technique was used to help the silver nanoparticles sinter to form a dense structure with a hot press temperature and pressure of 250oC and 5 MPa, respectively. Internal pre-existing pores existed (porosity about 7%). The internal pore structure was expected to alter during current-stressing. The parameters of the current-stressing test were a temperature of 250℃ and a current density of 5x105 A/cm2. We discuss the microstructure change in the silver nano-stripe and electromigration for different time points. In the interruption test, the silver nano stripe did not occur obvious electromigration phenomenon at 48 hrs., which means that it did not form hillocks at the anode or voids at the cathode on the surface. However, voids formed all over the silver nano-stripe, and hillocks developed near the middle and cathode at 140 hrs. and 216 hrs. The porosity decreased from the cathode (23.5±4.5%) to the anode (4.6±1.2%), which follows the direction of the electron force.