The True Value of Connector Inspection: New Challenges and Best Practices Vincent Racine Product Line Manager August 2011 1
Table of contents 1 Best Practices 2 Connector Inspection Tools 3 Connector Inspection Criteria 4 Automating Connector Inspection 5 Connector Cleaning 6 Failing Connectors: Possible Causes 2
Best Practices 3
Best Practices What is the first step to any fiber testing? Cleaning Connector inspection 4
Best Practices Who should inspect connectors? Why? Any person handling optical fiber Particles on connectors can: Cause strong back reflections, which can lead to instability in the laser system Permanently scratch the connector ferule Cause an air gap or misalignment between the fiber cores, which significantly degrades the optical signal Degrade insertion loss (IL) and return loss (RL) connector performances Burn and permanently damage connector endfaces Affect the connector performance FACT: 1µm particle can block up to 1% of light (0.05 db) 5
Connector Inspection Tools 6
Most Common Inspection Tools Microscope Very affordable Only allows male connector ends inspection May not be always secure enough to inspect live fibers Fiber Inspection Probe & Display Affordable solution Allows inspecting male and female connectors Very secure, no direct eye exposure Fiber Inspection Probe on test instrument Affordable option Uses the instrument screen; no need for additionnal display Allows storage of images for record keeping Can perform automated analysis of images 7
Connector Inspection Criteria 8
Connector Inspection Challenges Connector inspection requires a great amount of judgment Should I change/clean this connector or not? How large are the particles? Do they matter? 9
Connector Inspection Challenges Manual inspection: Acceptance level may vary greatly from a user to another User may pass a defective connector, which can translate into additional truck rolls User may systematically fail a good connector, which can lead to unnecessary rejects Qualification 10
Connector Inspection Criteria Criteria are defined in the following standards: IEC 61300-3-35 Fiber-Optic Interconnecting Devices and Passive Components Basic Test and Measurement Procedures http://webstore.iec.ch/ IPC 8497-1 Cleaning Methods and Contamination Assessment for Optical Assembly http://www.ipc.org/ 11
IEC 61300-3-35 Connector Inspection Criteria Visual requirements are defined by connector and fiber types: SM-UPC (RL >45 db) SM-APC SM-PC (RL >26 db) MM Multifiber 12
IEC 61300-3-35 Connector Inspection Criteria A connector endface is divided into multiple zones Dimensions will depend on the connector and fiber type Multimode and singlemode connectors have different sizes IEC zone sizes for PC polished connectors, multimode fibers IEC zone sizes for polished connectors, singlemode non-dispersion shifted fiber, RL 45 db Core 0-65 µm Cladding 65-120 µm Core 0-25 µm Cladding 25-120 µm Adhesive 120-130 µm Contact 130-250 µm Adhesive 120-130 µm Contact 130-250 µm 13
IEC 61300-3-35 Connector Inspection Criteria There are many types of defects: particles, pits, chips, scratches, embedded debris, loose debris, cracks, etc. In standards, defects are divided into two groups: 1. Scratches: permanent linear surface features 2. Defects: all non-linear features detectable on the fiber; this includes particulates, other debris, pits, chips, edge chipping, etc. 14
IEC 61300-3-35 Connector Inspection Criteria Tolerances will differ for each zones Number of defects Number of scratches Size of defects and scratches IEC visual requirements for polished connectors, singlemode non-dispersion shifted fiber, RL 45 db Zones Scratches Defects A: Core None None B: Cladding No limit 3 µm None >3 µm No limit <2 µm 5 from 2 5 µm None >5 µm C: Adhesive No limit No limit D: Contact No limit None 10 µm 15
Automating Connector Inspection 16
ConnectorMax Pass/Fail Analysis Software Automation is the only way to comply to IEC and IPC standards Size and location of defects must be measured down to microns It is virtually impossible to qualify a connector against a standard with manual inspection Where are the zones? What is the size of each particle? How many defects are there? Am I exceeding the limits? 17
ConnectorMax Pass/Fail Analysis Software ConnectorMax will save valuable time where it matters the most: in the field EXFO is a pioneer in developing inspection tools integrated into test solutions ConnectorMax was the first analysis software to be integrated into a test instrument Using ConnectorMax, entry-level technicians will automatically get: Connector certification against IEC and IPC standards Detailed analysis information Full report documentation ConnectorMax analytical software on the FTB-1 compact OTDR 18
ConnectorMax Pass/Fail Analysis Software Using an analytical software like ConnectorMax allows to: Guarantee a uniform level of acceptance: Between users within an organization Between suppliers and customers Between contractors and network owners Facilitate decision process by removing subjectivity 19
ConnectorMax Pass/Fail Analysis Software ConnectorMax provides: Reporting capabilities for record keeping Proof of compliance to IEC or IPC standards Detailed defect analysis 20
ConnectorMax Pass/Fail Analysis Software Full-link certification reports Connectors offer flexibility to optical links but they can also become their weak points Testing with an OTDR does not allow characterization of the far-end connector OTDR is a single-ended tool Using an inspection probe and ConnectorMax allows to certify the far-end connector Mechanical splice Fiber section Fiber section Patch Panel Patch Panel 21
ConnectorMax Pass/Fail Analysis Software Full-link certification reports: A global pass/fail status for the entire link OTDR: fiber and splices ConnectorMax: connectors (patch panels) 22
Connector Cleaning 23
Cleaning The IEC 61300-3-35 standard suggests an attempt to clean before rejecting a connector If the fiber fails inspection for defects, the user shall clean the fiber and repeat the inspection process. Some organizations standardize using different approaches, such as performing up to three cleaning attempts before rejecting 24
Cleaning Dry method An efficient technique for removing light contaminants Often considered the technique of choice in a controlled manufacturing environment where speed and ease of use are important factors Advantages Convenience of readily available tools Fast and easy Disadvantages Can possibly create electrostatic charges Not effective in removing all contaminant types Example of dry cleaning supplies: Specialized lint free wipes and swabs Mechanic cleaning devices 25
Cleaning Wet method The main purpose of using the wet-solvent approach is to raise dust and contaminants from the connector s endface to avoid scratching the connector The most widely-known solvent in the industry is the 99.9% isopropyl alcohol (IPA), which removes most contaminants Advantages Can dissolve complex soils and contaminants Eliminates the accumulation of electrostatic discharge on the ferrule Disadvantages Can leave residue on the ferrule when too much solvent is used and not properly dried Solvent choice can be confusing with issues of performance and EH&S Example of wet cleaning supplies: Pre-saturated swabs 26
Cleaning Combination method (hybrid) Combination cleaning is a mix of the wet and dry cleaning methods The first step in hybrid cleaning is to clean the connector end-face with a solvent and to dry any remaining residue with either a wipe or a swab Advantages Disadvantages Cleans all soil types Reduces potential static field soil accumulation Automatically dries moisture and solvent used in the cleaning process Captures soil in wiping material as an integrated aspect of cleaning procedure Requires multiple products Example of combination cleaning supplies: Specialized wipes and solvents Not expensive 27
Failing Connectors: Possible Causes 28
Connector Issues A fail result will not identify the problem The first step in solving a problem is understanding it The image of a connector can tell a lot Different issues may be recognized by looking at the image Wrong cleaning technique Mishandling Chips Pits/dust particles Scratches 29
Connector Issues After drying Wet residue: Most often caused by an improper cleaning technique fibers must be dried after a wet cleaning When drying, remaining dust particles will migrate toward the core Proper cleaning will remove the residue 30
Connector Issues Oil residue: Most often caused by touching the fiber end users must never touch fiber ends An oil residue may act as a matching gel: May not affect IL and RL short term May trap dust and increase IL and RL with time Additional truck rolls: $$$ Proper cleaning will remove residue 31
Connector Issues Dust/dirt residues transfer: If not cleaned properly: Residues will transfer and may create permanent damage when mating Before mating: After mating: Patch Panel 32
Connector Issues Circular residue: Most often caused by improper cleaning technique Show when fiber is mated while still wet Patch Panel Typically happen within the contact area Contamination will migrate from male to female fiber ends Proper cleaning will remove the residue 33
Connector Issues Adhesive region defects: May originate during the manufacturing process or a mishandling Epoxy and chips may show in this region Are most often permanent defects May show as dark or light defects Are normal if size does not exceed the IEC and IPC criteria 34
Connector Issues Scratches: Are linear defects in nature Are critical if appearing in the core area May originate from mishandling or improper cleaning technique Are permanent defects May be normal if they are on the ferule surface (contact zone) depending on manufacturing techniques and connector grade 35
Connector Issues Scratches: May appear as light or dark defects May be hard to see with the naked eye Are critical if appearing in the core area of SM fibers 36
Conclusion The IEC and IPC standards are defining inspection criteria Inspection is the first step to fiber testing Integrated inspection probes on test instruments represents the most convenient and secure approach to fiber inspection Cleaning is a critical step Proper cleaning supplies and methods must be followed Using analytisis software such as ConnectorMax: Is the most effective solution to standardize inspection procedures Provides means of certification for the entire network (fiber and connectors) against IEC and IPC standards 37
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Vincent Racine EXFO Product Manager OPTERNUS GmbH German Distributor www.opternus.de August 2011 39