Ultra-Millisecond Flip-Chip Bonding Process via Intense Pulsed Light Irradiation

Area of Science:

• Materials Science
• Manufacturing Engineering
• Semiconductor Packaging

Background:

• Flip-chip ball grid array (FC-BGA) packages are critical in modern electronics.
• Ensuring the mechanical reliability of solder joints is essential for device longevity.
• Conventional reflow processes can lead to suboptimal intermetallic compound (IMC) formation and joint strength.

Purpose of the Study:

• To investigate an intense pulsed light (IPL) flip-chip bonding process for enhanced FC-BGA mechanical reliability.
• To optimize IPL parameters for reduced bonding time and temperature.
• To analyze the impact of IPL bonding on solder joint microstructure and mechanical properties.

Main Methods:

• Utilized in situ temperature and resistance monitoring for real-time bonding data.
• Developed and validated a numerical thermal transient simulation model.
• Employed scanning electron microscopy (SEM) to examine solder joint microstructure.
• Conducted die shear tests to evaluate mechanical reliability.

Main Results:

• IPL bonding significantly shortened process time from 90s to 56.4ms.
• Maximum bonding temperature was reduced from 250°C to 221.7°C.
• Intermetallic compound (IMC) thickness was reduced from 6 μm to approximately 800 nm.
• Die shear force improved by 30% compared to conventional reflow.

Conclusions:

• IPL flip-chip bonding offers a highly effective method for improving the mechanical reliability of FC-BGA packages.
• The optimized IPL process leads to finer IMCs and enhanced solder joint strength.
• This technology presents a promising alternative for advanced semiconductor packaging manufacturing.