The Effects of Water Soluble Paste Formulation on the Ball Attach and Ball Shear Failure
Authors: Li Tianpeng, Jorcelyn Tan Ying Ru, C. D. Breach and A. Hawkins Company: Kester Date Published: 5/13/2014
ICSR (Soldering and Reliability)
Abstract: The solder balls attach of two water-soluble solder pastes, a novel zero halogen material and a halogenated material, was compared in nitrogen and air atmospheres after reflow in a Malcom Reflow Simulator. Videos of the reflow process showed that both pastes reflowed well in nitrogen. After air reflow the zero halogen paste exhibited good ball attach capability without defects and minimal degradation while the halogenated paste showed head-in pillow defects. Decomposition and weight loss of the pastes in air and nitrogen was studied using Thermogravimetric Analysis (TGA). The weight loss of the zero halogen paste in air and nitrogen atmospheres was similar which indicated that the presence of oxygen had a minor effect on the ability of the flux to protect the solder alloy. However, the halogenated paste exhibited significantly greater weight loss in air compared with nitrogen, demonstrating the poorer protection of the solder against oxidation due to the poorer thermal stability of the halogenated flux. Wetting balance results showed that the wetting force obtained with the zero halogen paste was very stable with the time, whereas the wetting force obtained with the halogenated paste displayed was unstable wetting force and decreased with time. Ball shear testing was conducted at different shear speed. Failure mode and failure force was analysed.