Laser Assisted Reflow Process for Solder Bump Interfaces

This technical report introduces and evaluates a contactless laser-assisted reflow (LAR) process aimed at creating stable solder bump interfaces on semiconductor substrates. The study focuses on minimizing the CO2 emissions associated with conventional oven-reflow methods, which require significant energy and gas consumption. The research utilizes silicon chips and flexible FR4 substrates to assess the effects of the LAR process on solder joints made from SAC305 and Sn42Bi58 materials. Various analytical techniques, including shear tests and thermal cycling tests, are employed to compare the soldering quality of laser-reflowed samples against conventionally reflowed samples. The report details the laser reflow process, including the equipment used, the modulation of the laser beam, and the introduction of process gas to prevent oxidation. Additionally, it discusses the benefits of the LAR process, such as reduced thermal impact and enhanced intermetallic compound properties, contributing to the reliability of solder connections. The findings suggest potential applications and future prospects for this technology.