High Coupling Efficiency Adhesive for Photonic Packaging

The rapid rise of 5G and artificial intelligence (AI) has accelerated the demand for high-speed data communication and driven the evolution of advanced packaging technologies such as 2.5 D and 3 D architectures for AI applications. Within this field, silicon photonics packaging is becoming an attractive alternative to conventional copper-based electronics, offering faster data transfer with lower power consumption. Although electronic packaging has seen remarkable progress, photonic integrated circuit (PIC) packaging still faces major hurdles in achieving consistent performance and reliability. Key challenges include the need for highly accurate and efficient active alignment for optical coupling, ensuring durability during reflow and environmental testing, and managing heat dissipation effectively. Adhesives play a vital role throughout the photonic packaging process, providing solutions to these technical barriers. Their properties-such as bonding strength, optical transmission, and resistance to environmental impact are crucial factors determining the success of packaging applications. This paper examines the primary bonding tasks in photonic packaging and outlines the specific requirements that adhesives must meet. Emphasis is placed on both the optical and mechanical characteristics of adhesives, as well as their ability to retain stable performance under varying operating conditions. Recent advancements in adhesive technology are also highlighted, demonstrating how they improve efficiency and reliability in photonic devices, supported by experimental results on coupling efficiency. In addition, the paper presents a wafer-level photonic packaging method designed to preserve optical performance during key steps such as sawing and grinding. By selecting materials with specialized optical properties, this approach ensures that the packaging process maintains the integrity and functionality of photonic components.