Characterizations for 25G/100G High Speed Fiber Optical Communication Applications with Hermetic eWLB (Embedded Wafer Level Ball Grid Array) Technology

Abstract

As the fan-out wafer level package (FOWLP) technologies have become the popular solution for the next level of thin, high speed, high frequency and fine routing pitch packaging capability, the Embedded Wafer Level Ball Grid Array (eWLB) is designed to address the growing mismatch in interconnection gap, higher level of integration, improved electrical performance and shorter vertical interconnects. The eWLB technology is a versatile FOWLP platform providing a robust packaging platform to achieve a more space-efficient package design enabling the very dense interconnection and routing of multiple-dies, a smaller footprint and lower package profiles and a very reliable package solution. Due to the benefits of shorter interconnection length, lower conductor loss with smooth Cu surface as well as lower dielectric constant and dielectric loss of polymer layers at high frequency, eWLB is a suitable packaging solution for high speed and high frequency applications, especially in the applications of 5G/mmWave, automotive radar, fiber optical communication (FOC) and others. Among these applications, the FOC device has been viewed as the core technology to be developed to meet high-density, high-speed optical interconnects demands for devices used in communication networks, high performance computing (HPC) and data centers. This paper addresses the hermetic eWLB package characterization, assembly process and reliability study in two different FOC devices, the 25 Gb/s high speed single channel optical receiver and DML (directly modulated laser) transmitter as well as the 100 Gb/s high speed quad-channel DML transmitter. The characterization data includes optimization of equipment handling, wafer singulation, reconstitution process, warpage characterization of molded wafer and device electrical validation are reported. In addition, the package level long-term reliability tests are evaluated to examine the reliable quality and yield of these eWLB packages. The result shows that the eWLB technology is a robust and cost-effective package solution for high bandwidth and weather-proof FOC applications.