Sources of End Face Contamination on Fiber Optical Interconnects and Recommended Best Practices for Removing the Contaminates Brian Teague Product Line Manager 18 November 2016
Program Agenda 1. Do It Right The First Time 2. Residues Contamination 3. Dust Contamination 4. Electrostatic Charge 5. Solve the Problem
Do It Right The First Time A study of 300 reported failure causes of fiber cabling revealed: 57% (172) dig ups 7% (22) craft and workmanship failures 5% (16) unknown 4% (13) rodents 4% (11) fire 3% (8) defective cable 2% (6) flood 1% (4) lightning If you don t have time to do it right, when will you have time to do it over? Albert Einstein Source: Sumitomo Lightwave Optical Fiber Cable Design & Reliability P. VanVickle May 2014 for IEEE802
Industry Statics on Fiber Connector Cleaning HTI Martin Technical Research Survey of 89 network owners and network contactors study on network failure. 80% of Network Owners and 98% of Network Contractors have experienced fiber failures during the installation process 82% of Network Owners and 92% of Network Contractors use IPA as the cleaning agent 12% of Network Owners and 30% of Network Contractors use compressed air for cleaning Truck Roll Back Expense Stats: The average truck roll is ~ $150 NOT including labor. Labor $50/hour. The average PRISM truck roll results in a three hour visit. Matt Olson, Principal Architect at CenturyLink at CONF 2014 National Association of Regulatory Utility Commissioners estimates a truck roll costs upwards of $275 in 2014 and that does not take into consideration the cost of parts.
Case Study on Installation Expenses US National Association of Telecommunications Officers & Advisors Installation of new fiber cables added to an existing community network Adding 11KM of new fiber cables to connect to 9 buildings schools, fire station and government buildings Medium density suburban area outside of Washington, DC Using 144F SM cable fiber for right of way
Case Study on Installation Expenses Right of Way for 11KM Cabling $192,750 Fiber Drop Costs for 9 sites $7,200 $723,200 $52,740 Materials Labor Materials Labor 80% of project expense was spent on labor Understanding and avoiding problems reduces the variability installation labor expenses An upfront investment in fiber cleaning consumables reduces initial upfront labor expenses and truck roll back expenses
Contamination Issues Residues Residues change the refractive index of the transmission medium The higher the frequency of the light signal, the greater the refractive angle Changes in the refractive angle causes a phenomenon called chromatic aberration Light Refraction Through Glass & Water Chromatic Aberration 60 Glass 60 Water 35 41 60 60
Sources of Residue Contamination Outgassing of end caps Plasticizers residues in components Skin Oil, Vegetable Oil, & Hand Lotion Cross contaminated cleaning alcohol Humidity Skin Oil Source: Image taken with PROMET FiBO Cross Contaminated IPS Source: Image taken with PROMET FiBO
Isopropyl Alcohol Cross Contamination Issues Alcohol is hygroscopic meaning it attracts water Highly flammable and high vapor pressure Menda style bottles pull air in to dispense the alcohol Presaturated wipes packaging breaks down over time and leeches into wipe
Contamination Issues Fusion Splicing Fiber Ø125μm Fiber Core Ø 9μm Singlemode Ø 50μm for OM3/OM4 Dust from paper based wipe Water residue from cross contaminated IPA Dust from cross contaminated IPA Dirty electrodes and dust in fiber grooves
Dust Contamination is Common Source: RSM using RSM1 scope
Contaminations Issues Dust Particulates Back Reflectance Insertion Loss Dust interferes with physical contact creating small air gaps and permanent end face defects Residues in signal path change index of refraction between the connector pair causing signal loss Absorption Loss
Sources of Dust Contamination Common Internal Contributors: Dead skin, hair, and clothing lint Packaging and construction materials Foam based swabs and paper based wipes Connector wear debris and dirty test assemblies Zinc whiskers from electroplated surfaces Protective end caps for connectors and adapters Zinc Whiskers Source: NASA Electronics Parts & Packaging Program Left: Dust from top of cabinet. Right: Paper Fiber(wood) from inside drawer Source: Karen Brynjolf Pedersen & Morten RyhlSvendsen National Museum of Denmark
Sources of Dust Contamination Environmental Contributors: Electricity generation & vehicle emissions Aerial blown dirt and sands Plant pollen and molds Concrete dust Flower Pollen Source: Dartmouth College Electron Microscope Facility Coal Ash Source: University of Kentucky Center for Applied Energy Research
Electrostatic Charge Contact Friction Before material contact, materials are not charged At material separation, materials are oppositely charged + + + + + + + + + + + + Material 1 3 Electrons +3 Protons 0 Net Material 2 3 Electrons +3 Protons 0 Net Material 1 2 Electrons +3 Protons +1 Net Material 2 4 Electrons +3 Protons 1 Net
Electrostatic Charge Attraction The Role of Electrostatic Charge Effect on Contamination of Fiber Optic Connectors and Ways of Eliminating it by T. Berdinskikh, A. Fisenko, J. Daniel, J.Bragg, D.Phillips of Celestica Applications of Photonics Technology 5, 420 (Feb 2003) 1. ST Connector is cleaned and image captured 2. ST placed 2mm above iron dust 3. ST placed 4mm above iron dust 4. ST placed 2mm above nickel dust Conclusions: The contact friction of the dry wipe created an electrostatic charge on the ceramic ferrule surface The oppositely charged dust particles bonded on the ferrule surface quickly
Electrostatic Charge Decay 1. Base line image of cleaned ST 2. 7 Day Observation 3. 14 day Observation 4. 30 day Observation Conclusions: The electrostatic charge on the ferrule surface came after the contact friction from the dry wipes The electrostatic charge remains and does not go away on its own
Sources of Electrostatic Charge Dry wiping connectors with wipes that do not have dissipative properties Cleaning only with compressed air Inserting or removing a connector into the adapter during mating Removing the protective end cap from the connector or adapter Connecting to test equipment Using foam based cleaning sticks to dry an end face
Installer Best Practice NO Clean It Is It Clean? Inspect the end face YES Always clean just before mating. Connect It! Cleaning process takes < 10 secs (How much time does it take to trouble shoot a problem?
Best Practices for Removing Contamination Wetdry cleaning is most effective for removing all forms of contamination and eliminates electrostatic charge Use optical grade cleaning fluids that are zero residue and fast evaporating Use cleaning fluids in hermitically sealed packaging to prevent cross contamination If you must use IPA, change it out frequently and thoroughly wash and dry (no water) the container When using stick cleaners, one stick per end face to avoid cross contamination When using sticks, rotate them in the same direction 6x to 8x times Mechanical cleaners are good for light and medium levels of contamination levels Boxes and tubs of optical grade wipes plus cleaning fluid are best for splicing pigtails to bulk cable Clean your test assemblies and ports of the test gear Always clean both ends of a mated connector pair just before mating
Cleaning Selection Guide What kind of contamination have the connectors been exposed to? Residues, Dust, Both Light, Medium, Heavy Levels What are the work conditions like at the work site? Ventilation and Air Flow Flammability Concerns Operating and Storage Conditions How do the cleaning fluids need to be transported? Air Shipment Requirements HAZMAT Restrictions Spill and Leak Concerns What are regulatory requirements? DOT Restrictions RoHS, REACH, GHS Compliance Substance
Final Thoughts Best Practices for Cleaning Fluid: Use hermetically sealed containers to avoid cross contamination Less is more Dispense just enough to clean a connector Best Practices for Sticks & Swabs: Rotate stick at least 6X in a single direction Limit force to about the same pressure you would use for a writing pen Never excessively scrub the end face to prevent scratching with wear particulates Best Practices for Wiping Connectors: Wipe connectors in a single direction Always wipe MT based connectors (i.e MPO) in a single direction vertical direction Tilt end face for APC so the 8 angle is touching the wipe General Best Practices: Never look directly into a connector with the bare eye Inspect, clean if necessary & reinspect Reusing wipes & sticks causes cross contamination
Thank You for your time. Questions? Technical Support Brian Teague Product Line Manager C: +1.860.406.2576 (US Based) Local Contact Jerald Chan Asia Market Manager C: +65.9688.7451 (Singapore Based)