TEST & MEASUREMENT
Detecting and correcting connector contamination Down and Dirty By Martin Warne, Senior Application Engineer, EXFO
Introduction All connectors, regardless of type, whether single fibre, multi fibre, P2P, FTTA or FTTH, must be clean. The effects of connector contamination are well-known in the industry and proper inspection is the best way to prevent problems. Obviously, the solution is not to just
Martin Warne discusses the best way to prevent network performance and quality issues.
systematically clean all connectors. They should only be cleaned when an inspection reveals that they are dirty. The objective is to know when and where to clean. As far as where to clean, the following items should always be on your inspection list: patch panels, test jumpers and cable connectors. Remember, cleaning can be done at all testing phases: construction, activation and maintenance.
Dirt and Defects When not properly cleaned, residues will transfer and may lead to permanent damage. A connector that is scratched, dirty or defective in any way, will have a direct negative impact on overall network performance and quality. These performance and quality problems will tend to grow as fibre networks expand to homes and other premises. Obviously, the more fibre there is, the
higher the chance of problems related to connectors. Connector contamination can be
dry, fluidic or a combination of the two. Common sources of contamination include residual grease/oils and dust from the storage or manufacturing process, exposed connectors, testing as well as scratches or chips that can or cannot be polished. The worst single contaminants are lubricants, sand, graphite, carbon black.
There are countless ways to contaminate a connector: • Environmental contamination from the surroundings
• Wet residue from incorrect drying techniques
• Oily residue from fingers • Circular residue from mating a still-wet connector
• Adhesive region defects from the manufacturing process or a result of mishandling
• Dirty, damaged connectors from poor handling or cleaning
• Scratches • Lack of cleaning tools and inappropriate cleaning techniques/equipment
Dry or Hybrid? There are two types of cleaning: dry cleaning and wet-to-dry or hybrid cleaning. Dry cleaning involves using a mechanical cleaner and a fabric to eliminate grease/oil and light dust particles. Hybrid cleaning involves using a solvent or an IPA solution to clean the endface and then dry it with a wipe or swab. The generic inspection technique,
which is supported by the IEC/TR 62627-01 document, is as follows: Dry clean > Inspect > Repeat two or three times > Hybrid clean > Inspect. However, regardless of the method
that is implemented, the goal remains to implement a technique that cleans a connector right the first time. This will lower costs, reduce worker frustration and encourage troubleshooting using OTDRs or other tools.
Inspection Tools In addition to a stringent cleaning method, the best way to confirm that a connector is in good condition is to use an inspection tool. Although, direct view microscopes are still available, the fact that they only inspect male connectors, that they are not always secure enough to inspect live fibres and that they increase the risk of exposure to laser radiation has led to the growing use of handheld inspection microscopes. In addition to using cutting-edge technology, these systems can generate files and images for easy viewing and follow-up. Once a connector is clean, its
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permanent features should also be qualified. Connector qualification relies on industry standards like BS EN 61300-3-35, which is used to define the connector face areas that are of critical interest, i.e., the core, cladding, adhesive and contact. Unfortunately, this standard is also very broad in scope and applies to both new and old connectors, in every situation. This is a problem for 100G and higher data rates; they will need a specific standard. At the moment, there are four
possible results: All connectors must be clean. 18 NETCOMMS europe Volume III Issue 1 2012
1. Meets all BS EN 61300-3-35 conditions
www.netcommseurope.com
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