Transcript Megladon Manufacturing Group, Ltd.

Extending the Lifecycle of
Fiber Optic Cables
John Culbert
President and Partner, Megladon Mfg. Group
Austin, TX
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
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
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
Scratches and Pitting
Case Study –
International Electronics Manufacturing Initiative (iNEMI)
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 Descriptions
Zone 3
Ferrule
Zone 1C
Epoxy Ring
Zone 2
Contact Area
Zone 1B
Cladding
Zone 1A
Core
Zone 3
Ferrule
Inspection Criteria
From IPC-8497-1
Cleaning Methods and Contamination Assessment for Optical Assembly
Allowable Visible Contamination
Zone
Description
Diameter
Non-Removables
1a
Area Near Core (SMF
only)
None
None
Area Near Core (MMF only) < 66 um
Total of 5 NRs < 5um
None > 5um
Total of 5 scratches < 3
um
None > 3 um
Cladding 7 (SMF Only)
25 um to 125 um
NRs < 2 um are
Acceptable
Total of 5 NRs < 5um
None > 5um
None > 3 um
Cladding 7 (MMF Only)
66 um to 125 um
NRs < 2 um are
Acceptable
Total of 8 NRs < 5um
None > 5um
None > 3 um
--
Epoxy Ring Zone
120 um to 130 um Any
Any
2
Contact Diameter 8
130 um to 250 um None > 10um
None > 3 um
3
Ferrule Diameter 8
250 um to 400 um None > 30 um
Any
1b
< 25 um
Scratch Width
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
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
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.
Contamination
Case Study – iNEMI
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
5th Mating, 200x
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
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
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
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
Inspection Best Practices
Inspection Criteria - Revisited
Zone Descriptions
Allowable Visible Contamination
Zone
Description
Diameter
Non-Removables
1a
Area Near Core
(SMF only)
Area Near Core
(MMF only)
1b
-2
3
Scratch Width
< 25 um
None
None
< 66 um
Total of 5 NRs <
5um
None > 5um
Total of 5 scratches
< 3 um
None > 3 um
NRs < 2 um are
Acceptable
Cladding 7 (SMF
25 um to 125
Total of 5 NRs <
Only)
um
5um
None > 5um
NRs < 2 um are
Acceptable
Cladding 7 (MMF
66 um to 125
Total of 8 NRs <
Only)
um
5um
None > 5um
120 um to 130
Epoxy Ring Zone
Any
um
130 um to 250
Contact Diameter 8
None > 10um
um
250 um to 400
Ferrule Diameter 8
None > 30 um
um
None > 3 um
Zone 3
Ferrule
Zone 1C
Epoxy Ring
Zone 1B
Cladding
Zone 1A
Core
None > 3 um
Any
None > 3 um
Any
Zone 2
Contact Area
Zone 3
Ferrule
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
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
Cleaning Best Practices
From IPC-8497-1
Comparison of Cleaning Fluid Properties
Installation Guidelines
Fiber Mechanical Limits
•Maximum Cable lengths
•Minimum Bend Radius
•Pull Tension Restriction
Installation Guidelines
•Never Pull by the Connector
•Use Pulling Eye or Grip for
Trunks
•Monitor Pulling Tension
•Use “Straight Pull”
•Do not twist cable
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
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
Tempered Mating Surface
Benefits
Easy to install
Repeatable Network Performance and Reliability
Reduced Network Downtime
Increased Customer Satisfaction
Saves Time and Money
Tempered Mating Surface
Visual Inspection Summary Report
December 9, 2008, 11:24:51 AM
File Name
No Insertions
Serial Number 2567812
Inspection Summary
Diameter (um)
Zone Name
Inner
Outer
Zone A
0
25
Zone B
25
120
Zone C
130
240
Zone D
240
400
Core Size
9um Fiber type
Pass
Scratches
Result
Count
Pass
0
Pass
0
Pass
0
Pass
0
Simplex
Fiberchek2, Westover Scientific Inc.
Visual Inspection Summary Report
December 11, 2008, 3:45:44 PM
File Name
1000 Insertions
Serial Number 2567812
Inspection Summary
Diameter (um)
Zone Name
Inner
Outer
Zone A
0
25
Zone B
25
120
Zone C
130
240
Zone D
240
400
Core Size
9um Fiber type
Fiberchek2, Westover Scientific Inc.
Pass
Scratches
Result
Count
Pass
0
Pass
0
Pass
0
Pass
0
Simplex
Tempered Mating Surface
Number of Matings VS Insertion Loss
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
References
(1) “Accumulation of Particles near the Core during
repetetive Fiber Conenctor Matings and Dematings.” 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