Development of cleanliness specifications for single-mode connectors with 1.25 and 2.5 mm ferrules

Contaminated optical connectors result in degradation of optical performance, functional failures, and increased deployment costs. Currently there is no widely accepted cleanliness standard based on a systematic study of the impact of cleanliness on the optical performance of fiber optic connectors. This paper summarizes the latest research of iNEMI (International Electronics Manufacturing Initiative) on development of cleanliness specification for fiber optics connectors. This research is used as a baseline for the development of IPC-8497-1 "Cleaning Methods and Contamination Assessment of Optical Assembly" standard. It compares the influence of Arizona road dust particles on the optical performance of 2.5 mm ferrules, (SC and FC), and 1.25 mm ferrules, (LC and MU) type connectors. The team measured the insertion loss (IL), return loss (RL), and the geometric parameters for both clean and contaminated connectors. Fiberscope images of the connectors before and after each mating operation were also recorded. Correlations in the changes in optical performance were analyzed as a function of the level, size, and location of the contamination. The IL and RL data were analyzed using statistical methods and images were analyzed using automated software. The particle number, size and occluded area were identified as critical factors on optical signal performance. Based on the experimental results and statistical analysis, the iNEMI team has developed a proposal for an inspection criteria matrix for 1.25 mm ferrule and 2.5 mm SM UPC connectors. The iNEMI team continues to work with IEC Working Group 6, the TIA and the IPC on universally accepted industry standards for cleanliness of fiber optics connectors. The acceptance of an industry standard for single-mode (SM) connectors will result in significant cost savings to the fiber optics industry due to the elimination of insufficient cleaning , over-cleaning, and/or the reduction of contaminated non-conforming material.