Fiber Optic Ferrule Delamination Prevention via Pre-Compression
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Solution Overview
Problem
The mismatch in coefficient of thermal expansion (CTE) between epoxy, fiber optic ferrules, and optical fibers leads to delamination during temperature changes, limiting the operating temperature and causing optical performance issues due to air gaps and reflections.
Innovation Solution
Applying an external compressive force greater than the thermal expansion force during the curing process to maintain the optical fibers and epoxy securely within the ferrule, using a cap and resilient member to ensure internal compressive forces between the fibers and ferrule, and employing UV light for curing to prevent delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy is used to bond optical fibers to the ferrule, then strong bonding is achieved, but delamination occurs during thermal expansion
Solution Approach 1:
The patent applies preliminary anti-action by pre-compressing the epoxy-bonded fiber assembly before thermal expansion occurs. A compression element is positioned to apply continuous compressive force on the ferrule, counteracting the tensile stresses that will develop during thermal cycling. This preventive measure stops delamination before it can occur by maintaining compressive contact between the epoxy and bonding surfaces throughout temperature variations.
2Manufacturing precision
If the ferrule is heated to cure the epoxy, then the epoxy hardens and secures the fibers, but air gaps form due to differential thermal expansion
Solution Approach 1:
The patent implements preliminary action by applying compression to the ferrule assembly before the epoxy curing process begins. The compression element is positioned and activated prior to heating, ensuring that the epoxy remains under compressive stress throughout the entire curing cycle. This pre-applied compression prevents the formation of air gaps during thermal expansion, ensuring uniform bonding and precise fiber positioning is maintained throughout the curing process.
3Temperature
If the operating temperature is increased, then the ferrule expands, but the epoxy bond fails due to expansion forces
Solution Approach 1:
The patent applies parameter changes by fundamentally altering the stress state of the epoxy bond from tensile to compressive through the continuous application of external compression. By changing the mechanical parameter (stress type) through the compression element, the system can withstand higher temperatures without bond failure. The compressive pre-stress counteracts the thermal expansion forces, allowing the operating temperature to increase while maintaining bond integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents epoxy delamination, ensuring secure bonding and maintaining optical performance across a wider temperature range by maintaining the applied force during curing, thus reducing air gaps and reflections.
Implementation Method 1
a resilient member (e.g., a spring) that provides a compressive force on the fiber optic ferrule
Implementation Method 2
employing UV light for curing to prevent delamination
Data Source
AI summary
A method for terminating a fiber optic ferrule included applying a force to a fiber optic ferrule while simultaneously holding the optical fibers. The fiber optic ferrule uses epoxy to hold the optical fibers, the epoxy can be either heat or light cured. The force is applied through a pusher that engages a cap on the front end of the fiber optic ferrule.