Advanced packaging, also known as High Density Advanced Packaging (HDAP), employs advanced design concepts and integration processes to reduce wire interconnect lengths, reconstruct chip-level system packaging, and effectively enhance system functional density. Current advanced packaging technologies include Flip Chip, Wafer-Level Packaging (WLP), 2.5D packaging (Interposer, Redistribution Layer/RDL), and 3D packaging (Through-Silicon Via/TSV).

Flip chip packaging involves first creating metal bumps on the chip. The chip is then placed face-down and directly interconnected with the substrate using solder. Epoxy-based resin or similar filler materials are dispensed along the edges of the device. Utilizing capillary action, these materials infiltrate to the bottom of the package, filling the gaps between the solder balls. Finally, the assembly is heated to cure the material, forming a complete underfill structure. The underfill adhesive primarily serves the following functions for the chip:

1. Form a protective barrier: Underfill adhesive effectively fills voids in the package, protecting weak points in the structure from environmental factors such as moisture and ionic contaminants.

2. Enhance reliability: Underfill adhesive absorbs stresses caused by CTE (Coefficient of Thermal Expansion) mismatches between different materials during temperature cycling, preventing solder joint fatigue and functional failure. It also mitigates mechanical stresses on solder joints under dynamic impacts like drops, thereby improving overall package reliability.

3. Improve thermal conductivity: Underfill materials for flip chips exhibit higher thermal conductivity than air, acting as a thermal medium to assist heat dissipation from the chip, enhancing performance and stability.

However, flip chip underfill adhesive faces several technical challenges, including:

1. Flowability and fillability: Flip chip underfill must exhibit excellent flowability and fillability to achieve uniform and complete coverage between the chip and substrate. This is particularly challenging for high-density chips and fine-pitched solder bumps.

2. Packaging process control: Flip chip underfill requires rapid curing within a specific timeframe to maintain stability. Precise control of curing temperature and pressure is critical to avoid introducing stresses or damaging the chip.

3. Material compatibility: Underfill materials must be chemically compatible with the chip, substrate, solder bumps, and other components to prevent adverse reactions or performance degradation.

CollTech is committed to becoming a materials application expert that addresses industry pain points, delivering high-performance materials application solutions and high-quality customized services to customers. CollTech’s flip chip underfill exhibits excellent flowability, fillability, and aging resistance, effectively enhancing chip reliability.

Typical Products:

EW 6364 is a one-part, solvent free, thermal curing adhesive based on epoxy system. It is designed for protection of chips as an underfill adhesive.

1. High Tg, Low CTE

2. Good flowability and easy filling

3. Compatible with various flux residues

4. High reliability

5. Excellent aging resistance

6. Fast curing at low temperatures

For more information, please contact us.