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 fiber optic connectors.The 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), with the performance of 1.25 mm ferrules, (LC and MU).The team measured the IL, RL, and the geometric parameters for both clean and contaminated connectors. Fiberscopic 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 Fiberscopic images were analyzed using automated software. The particle number, size and occluded area were identified as critical factors on optical signal performance.Specifically, contamination of the 25 um diameter zone around the core resulted in IL increases of up to 1.8 dB for 2.5 mm ferrule connectors and up to 1.1 dB for 1.25 mm ferrule connectors. Contamination of this zone near the core, along with the presence of clusters of particles with a diameter of more than 30um in the cladding may result in catastrophic changes of RL of 10-40 dB for all examined connectors.Contamination can prevent direct physical contact creating an air gap between two endfaces. The air gap was calculated based on the RL data and the maximum contact diameter was also evaluated. It was also shown that removable contamination can migrate towards the core during repeated mating/demating operations particularly for 1.25 mm ferrule connectors as shown in Figure 1. In 60 % of all examined LC and MU connectors a series of five repeated matings/demating operations resulted in an increase of IL of up to 0.5-1.1 dB due to particle movement from the ferrule and cladding areas towards the core. SC and FC connectors appear to be more resistant to particle movement during repeated mating/demating operations.Based on the experimental results and statistical analysis, the iNEMI team has developed a proposal for an inspection criteria matrix for 2.5 mm ferrule and 1.25 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 SM connectors will result in significant cost savings to fiber optics industry due to the elimination of insufficient cleaning and over cleaning and the reduction of contaminated non-conformance material. Figure 1. The fiberscopic images of MU contaminated connector after (a) the first (IL1=0.12dB, RL1=51dB) and (b) the fifth (IL5=1.23dB, RL5=15dB) mating/demating operation.
© 2006 Optical Society of AmericaPDF Article