Reliability Evaluation of Board-Level Flip-Chip Package under Coupled Mechanical Compression and Thermal Cycling Test...

Area of Science:

• Materials Science and Engineering
• Mechanical Engineering
• Reliability Engineering

Background:

• Flip Chip Ball Grid Array (FCBGA) packages are crucial for high I/O density and high-performance computing.
• External heat sinks improve thermal dissipation but can negatively impact solder joint reliability.
• Understanding these trade-offs is vital for advanced electronic packaging.

Purpose of the Study:

• To investigate the impact of heat sinks on the solder joint reliability of lidless on-board FCBGA packages.
• To analyze the effects of heat sink presence and loading distance on reliability under thermal cycling.
• To provide insights for optimizing the design of high-performance electronic packages.

Main Methods:

• Construction of a three-dimensional (3D) numerical model for FCBGA packages.
• Simulation of thermal cycling test conditions (JEDEC standard test condition G: -40 to 125 °C).
• Validation of the numerical model using experimental warpage measurements from a shadow moiré system.

Main Results:

• The numerical model accurately predicted FCBGA package warpage, confirming its validity.
• The addition of a heat sink was found to increase solder ball creep strain energy density (CSED).
• A longer loading distance also contributed to increased CSED, negatively affecting reliability.

Conclusions:

• Heat sinks, while beneficial for thermal management, significantly reduce the board-level thermal cycling reliability of FCBGA packages.
• Increased solder joint inelastic strain energy density is the primary mechanism for reliability degradation.
• Design considerations for heat sinks and loading distances are critical for ensuring the long-term reliability of high-performance computing packages.