Mechanical Reliability Assessment of a Flexible Package Fabricated Using Laser-Assisted Bonding

Area of Science:

• Materials Science and Engineering
• Microelectronics Packaging
• Advanced Manufacturing Technologies

Background:

• Flexible electronic devices require advanced packaging solutions that balance thermal management, mechanical integrity, and miniaturization.
• Traditional bonding methods often involve high temperatures, limiting substrate choices and potentially damaging sensitive components.

Purpose of the Study:

• To develop a flexible package technology utilizing laser-assisted bonding (LAB) and anisotropic solder paste (ASP).
• To reduce bonding temperatures and improve the flexibility and reliability of flexible electronic packages.
• To analyze heat transfer, mechanical deformation, and flexibility through experimental and simulation methods.

Main Methods:

• Fabrication of a flexible package using a silicon chip and a polyimide (PI) substrate.
• Application of laser-assisted bonding (LAB) with anisotropic solder paste (ASP).
• Experimental analysis and numerical simulations to study thermal and mechanical properties.

Main Results:

• Rapid solder melting (220 °C) achieved within 2.4 seconds using LAB, followed by quick cooling.
• Formation of stable interconnections without thermal damage to the polyimide substrate.
• Minimal warpage (80 μm) and low stress observed in the flexible package post-bonding.
• Demonstrated high flexibility, with devices bending up to 7 mm without failure.

Conclusions:

• Laser-assisted bonding (LAB) with anisotropic solder paste (ASP) is a viable technology for creating reliable and flexible electronic packages.
• The developed method offers excellent mechanical endurance and reliability, suitable for demanding flexible device applications.
• Further improvements in flexibility can be achieved by optimizing silicon chip thickness.