Effects of the degradation of methane sulfonic acid electrolyte on the collapse failure of Sn–Ag alloy solders for flip-chip interconnections. Issue 37 (27th April 2017)

• Record Type: Journal Article
• Authors: Park, Mi-Seok; Nam, Do-Hwan; Jung, Ki-Min; Hong, Kyung-Sik; Kwon, Hyuk-Sang
• Is Part Of: RSC advances. Volume 7:Issue 37(2017)
• Page Start: 23136
• Page End: 23142
• Publication Date: 2017-04-27
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c7ra02193c
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : The degradation mechanism of the methanesulfonic acid based electroplating bath used for the electrodeposition of Sn–Ag alloy solder bumps and its effects on the collapse failure of flip-chip solder bumps. Abstract : The present study investigates the degradation mechanism of a methanesulfonic acid (MSA) based electroplating bath used for the electrodeposition of Sn–Ag alloy solder bumps, and its effects on the microstructure of the solder and on the collapse failure of flip-chip solder bumps. To examine the degradation behavior of the electroplating bath, a degraded electrolyte is prepared by accelerated aging treatment. In the presence of dissolved oxygen and Ag + ions in the electrolyte, the chemical oxidation of Sn 2+ ions to Sn 4+ ions and the precipitation of SnO2 nanoparticles with a diameter below 100 nm are promoted by the reduction of Ag + . Under cathodic bias, colloidal SnO2 particles are adsorbed on the surface of the Sn–Ag solder bumps via electrophoresis, and incorporated into the layer by the electrodeposition layer of Sn–Ag. The presence of oxide layer mainly composed of SnO2 on the surface of the bumps significantly reduces the friction coefficient of the solder surface by hardening the electrodeposits and deteriorates the solderability of the solder bumps, which leads to collapse failure during solder reflow.