Development of Cleanliness Specification for Single - Mode Connectors

This paper summarizes research performed by the NEMI (National Electronics Manufacturing Initiative) Fiber Optic Signal Performance Project team. The project focused on the development of a cleanliness specification for single mode connectors. The influence of two grades of Arizona road dust on optical performance of single mode fibers is investigated. The researchers record insertion loss, return loss, and fiber optic microscope images for each connector pair before and after contamination. Interferometry data including radius of curvature, apex offset and fiber undercut are also recorded for each test and reference connector. The changes of insertion loss and return loss as a function of distance of the closest particle from the core are investigated. Results of mathematical modeling of contaminated fibers are correlated with experimental data. The results show that contamination particles can prevent direct physical contact creating an air gap between two end-faces. The area encompassed by a 25 _m diameter from the core is identified as critical. Particles located in this area, even if not directly on the core, result in an increase in insertion loss (a delta of 0.5 to 1.8 dB) and an increase in reflectance (a delta of 10 to 44 dB). Dust particles of 1-25 _m result in an air gap of up to 200 nm. The NEMI team is collaborating with the International Electrotechnical Committee (IEC), Telecommunications Industry Association (TIA) and IPC (Optoelectronic Assembly and Packaging Technology). Specifications will be jointly submitted to IEC SC86B Working Group 6 (interconnecting devices) for incorporation with IEC 61300-3-35, and to IPC as a draft of the IPC-8497-01 standard. In addition, the project will collaborate with TIA and IPC on the development of cleaning methods and contamination assessment for multi-level optical assemblies.