Cu Pillar Flip Chip Cleaning Chemistry Evaluation

This technical article presents an evaluation of cleaning chemistry for Cu Pillar flip chips, focusing on the challenges of cleaning Water Soluble (WS) flux residues. The article outlines the advantages of Cu Pillar technology in flip chip packaging, particularly in relation to miniaturization trends in electronics. It discusses the transition from solder bump technology to Cu Pillar technology and the associated cleaning challenges, such as partial cleaning due to fine pitch and low standoff gap height. The article details two case studies conducted by KYZEN Corporation, where they collaborated with manufacturers to assess and resolve cleaning issues. It describes the evaluation process of different cleaning chemistries, specifically comparing KYZEN's MICRONOX MX2708 with a previously used chemistry, Chemistry X. The evaluation considered various factors, including flux types, concentrations, and cleaning conditions, to determine the effectiveness of the cleaning agents in achieving complete solubilization of WS flux residues. The findings indicate that higher concentrations of cleaning chemistry are more effective in promoting solubility rates, which is critical for maintaining product reliability in advanced packaging applications.