Extending the Lifecycle of Fiber Optic Cables

1. Extending the Lifecycle of Fiber Optic Cables John Culbert President and Partner, Megladon Mfg. Group Austin, TX

2. Introduction • Fiber optic cables are considered a weakness in optical networks • Fiber cables are very fragile and sensitive to damage when handling • Making fiber optics meet performance expectations and withstand field/installation handling are important challenges • Industry Best Practices can help us achieve these goals, but robust connector technology can help us avoid the challenges

3. Outline • 1) Common Physical and Mechanical causes for Performance Decline in Fiber Optic Connectors • Inspection and evaluation criteria • Individual Factors • Case Study Discussions and Experimental Evidence • Industry Best Practices and Prevention Techniques • 2) Proposed Solution through Tempering Technology

4. Scratches and Pitting Scratches on the end face of a fiber optic surface drastically reduce its performance Scratches are created by: Improper Handling Improper Cleaning Insertions into Inspection Equipment Multiple Matings Any time the end face contacts something other than a cleaning tool or another properly oriented fiber end face, there is the potential for scratches to develop

5. Scratches and Pitting Case Study – International Electronics Manufacturing Initiative (iNEMI) Zone Descriptions Scratches have a negative effect on Return Loss (RL), a key fiber performance indicator Connectors under regular test environment use for 18 months saw return loss increased from -55db to an average of -42db Conclusions: Scratches significantly degrade optical performance, especially return loss Zone 3 Ferrule Zone 1B Cladding Zone 1C Epoxy Ring Zone 1A Core Zone 3 Ferrule Zone 2 Contact Area

6. Inspection Criteria From IPC-8497-1 Cleaning Methods and Contamination Assessment for Optical Assembly

7. Scratches and Pitting Prevention • Inspection – Follow inspection criteria. Any scratch can degrade performance • Proper Handling – protect end face at all times. Cap un-used connectors • Proper Cleaning – Use only approved cleaning products to prevent scratching • Carefully insert connectors into inspection ports – even this can create scratches Solutions • Proper Technician Training • More robust connectors that withstand handling

8. Contamination Contamination • Consists of dust, dirt and various other forms of debris • Difficult to avoid – Contamination happens anytime you remove the end cap and endface is exposed • Subject to the inspection guidelines mentioned earlier • Prevents even contact between cable end faces during mating • Blocks signal through core • 80% of contaminants are silica particles

9. Contamination Case Study – International Electronics Manufacturing Initiative (iNEMI) Experimental Dust Applied During repetitive connector mating and de-mating cycles, dust particles can accumulate and redistribute at the connector end face. Electrostatic charge force was one of the mechanisms responsible for the particle accumulation, redistribution and their movement in the core area.

10. Contamination Case Study – iNEMI 5th Mating, 200x Particles had a tendency to migrate specifically towords the core over the course of multiple matings The core is EXTREMELY sensitive to contamination. The accumulation of dust particles seriously impaired fiber performance A dust particle 5um wide in the core of a SM fiber assembly can effect more than one half of the signal

11. Contamination Best Practices – Per IPC-8497-1 • Always inspect and clean fiber connectors before insertion • Clean with dry wipes and cleaning fluid • Absorbent wipes of woven or entangled nature • Use IPA or other solvent to clean end face • Always clean with dry wipe again after solvent use • Clean connectors again when re-inserting in another port • Careful – some contamination can lead to scratches during cleaning • See IPC-8497-1 for cleaning methodology Solutions • Reduction in ESD Generation during cleaning • Smoother end face is more resistant to contamination gathering

12. Multiple Insertions • Multiple insertions can impact cable performance by: • Creating scratches • Increasing contamination • Migrating contamination towards core of fiber • Damaging epoxy ring • All connectorized fiber assemblies have a limited number of matings that they can withstand and still perform adequately

13. Multiple Insertions Case Study - iNEMI Based on iNEMI research in 60 % of all examined LC connectors, a series of five repeated matings/demating operations resulted in an increase of IL of 0.5 to 1.1 dB due to particle movement from the ferrule and cladding areas towards the core

14. Multiple Insertions Prevention Exercise Cleanliness Best practices between matings Verify both connectors are free of contaminants Solutions Develop connectors that are resistant to the effects of multiple matings Note that connectorized assemblies have a mating limit – replace cables that have exceeded their life cycle

15. Inspection Best Practices Inspection Criteria - Revisited Zone Descriptions Zone 3 Ferrule Zone 1B Cladding Zone 1C Epoxy Ring Zone 1A Core Zone 3 Ferrule Zone 2 Contact Area

16. Inspection Best Practices Keys to Successful Inspection Use Proper Inspection Equipment Bench Top Scope Handheld Scope, Port Probe Scratches can be identified @ 200x or 400x magnification Scratches and contamination on the core or cladding is unacceptable If scratches, re-polish the connector Contamination should be cleaned, then connector re-inspected

17. Cleaning Best Practices Keys to Successful Cleaning Use Proper Cleaning Equipment and Technique Dry Wipe on soft surface – Hard surfaces may damage ferrule Cleaning Cassettes IPA or other non-water based cleaning solvent Always use dry wipe after solvent use Contamination on the core or cladding is unacceptable Contamination should be cleaned, then connector re-inspected If contamination contains oils or residues, a solvent must be used

18. Cleaning Best Practices From IPC-8497-1 Comparison of Cleaning Fluid Properties

19. Installation Guidelines Fiber Mechanical Limits • Maximum Cable lengths • Minimum Bend Radius • Pull Tension Restriction

20. Installation Guidelines • Never Pull by the Connector • Use Pulling Eye or Grip for Trunks • Monitor Pulling Tension • Use “Straight Pull” • Do not twist cable

21. Proposed Alternative Tempered Mating Surface Accomplished by heat treating mating surface similar to a tempered windshield Hardness of Mating Surface increases Smoothness of mating surface increases

22. Tempered Mating Surface Features Scratch Resistant Promotes minimum insertion loss and return loss Heat anneals mating surface to prevent contaminant leaching Heat “heals” any imperfections near the end of the glass Smooth surface reduces ESD build up (less friction) Smooth surface reduces build up of contaminants Extended life span Easy Cleaning Durable enough to handle multiple matings Compatible with all existing connectors

23. Tempered Mating Surface Benefits Easy to install Repeatable Network Performance and Reliability Reduced Network Downtime Increased Customer Satisfaction Saves Time and Money

24. Tempered Mating Surface

25. Tempered Mating Surface Number of Matings VS Insertion Loss

26. Conclusions • Scratches and Contamination on Fiber Optic cables drastically reduce performance • By following industry best practices, we can prevent some scratches and make better efforts to keep connectors clean from contamination • Following these practices does not guarantee clean connectors and a scratch free surface • Tempering (heat treated) technology exists that creates a scratch resistant mating surface and extends the life cycle of the product

27. References (1) “Accumulation of Particles near the Core during repetetive Fiber Conenctor Matings and De-matings.” NFOEC 2007 Presentation. Berdinskikh, Tatiana, March 29, 2007 (2) “Cleaning Methods and Contamination Assessment for Optical Assembly.” OFC 2006 Presentation. Berdinskikh, Tatiana, March 6, 2006 (3) “Degradation of Optical Performance of Fiber Optic Connectors in a Manufacturing Environment.” iNEMI Presentation. Berdinskikh, Tatiana (4) “The Investigation of ESD effects on Mated Fiber Optic Connectors.” iNEMI Presentation. Culbert, John (5) IPC-8497-1 Cleaning Methods and Contamination Assessment for Optical Assembly