Chip-Level Packaging of Edge-Emitting Laser Diodes Onto Low-Cost Transparent Polymer Substrates Using Optodic Bonding

Nowadays, the optoelectronic industry increasingly occupies a pivotal position in modern communication fields. Packaging of optoelectronic components and modules ensures the reliable performance in mechanical, electrical, and optical properties. As the demand for a mechanical flexibility of optoelectronic packaging and also for a lower manufacturing budget is continuously growing, cost-effective transparent polymer foils are becoming more favored. They are employed for establishing novel planar optronic systems, which are applied as high-integrated sensing networks. In this contribution, we choose a bare edge-emitting laser diode as the light source for the optronic sensor systems and mainly investigate its optical performance in the chip-level packaging directly onto polymeric carrier substrates. Since these materials with low glass transition temperatures require thermal-restricted processes, we adopt previously developed optodic bonding utilizing light energy instead of heat energy to accomplish the chip-level packaging of the laser diode. However, the heat dissipation of the active optoelectronic components constitutes one of the most critical issues in their packaging technologies, even more severe because of the extreme low thermal conductivity of the employed polymer foils. Addressing this challenge, packaging of the laser diode die directly on the conventional substrate FR4 for printed circuit boards without any thermal management is attempted as a reference for packaging onto flex polymeric foils. The optical output power and the heat accumulation behavior in the form of the temperature of the active laser diode onto both substrates are measured and continuously monitored. Heat dissipation approaches based on accelerating the dissipation speed and reducing the heat accumulation are investigated.