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We characterize epoxy-related core cracking as a phenomenon because this problem can occur infrequently and irregularly. If you experience this, you can investigate the possible causes and solutions in this article.
Cure the epoxy by itself (not in your application) to ensure it meets the manufacturer’s specifications.
This simple experiment may offer clues to determine how to tweak your process. For example, if the epoxy takes longer to cure, you can keep it in the oven a bit longer or raise the temperature to ensure a complete cure.
It is common practice to inject epoxy into the rear of a ferrule, until a small bead of epoxy is observed exiting the ferrule tip. This is an effective way to ensure that the entire ferrule hole has been filled with epoxy prior to inserting fiber.
Starting from the point that the SC is an industry-standard connector, everyone knows that it is standardized on the connection point, meaning that all other areas like the inner housing, ferrule size and ferrule shape, housing color, backside, and strain relief boot are custom to the manufacturer.
From Our FOC Tips Series:
Backside: Traditionally SC connectors were accommodated with 3-3.5mm OD cable to withstand the IEC/Telcordia cable pull tests.
With the introduction of the smaller LC connector, which accommodates typically smaller OD’s like 2.0 or 1.6mm, the SC connector needed by many manufacturers a re-design to accept 1.6/2.0mm cables.
A critical eye on the backside design is needed to match it with the right cable manufacturer, taking the jacket thickness and the amount of Kevlar into consideration.
Some insight when it comes to changing a connector supplier….. let’s discuss a single-mode SC connector first for example:
Starting from the point that the SC is an industry-standard connector, everyone knows that it is standardized on the connection point, meaning that all other areas like the inner housing, ferrule size and ferrule shape, housing color, backside, and strain relief boot are custom to the manufacturer.
From Our FOC TIPS Series:
Inner Housing: most of today’s SC connectors are the ‘one-piece’ design which is an assembly of ferrule inner housing and backside. Often are the outer-housing, crimp sleeve, and strain relief boot in bulk packages separately provided. The traditional multi-piece design consists of more piece parts, like separate ferrule and spring and offers more flexibility. Customers can select various ferrule diameters as well as different connector backsides to accommodate bare fiber or different cables. Some of these connectors allows the ability for tuning.
In nearly all installation situations - in a patch-bay on an equipment rack, in a termination junction box, on the face-plate of electronic equipment - access to one of the connectors of any mated pair is very limited. If this “back-side” connector end-face is contaminated, it is very difficult (and sometimes impossible) to have access to remove the connector for cleaning.
This makes it even more important to ensure that these connectors, when installed, are in a clean and pristine a state as possible.
Fiber end-face defects (scratches, pits, cracks) and particle contamination have a direct impact on the performance of the connector, which contributes to poor IL/RL. Any irregularity that impedes light transmission from one fiber to the other will negatively affect IL and RL. If the fiber, anywhere within the assembly, is bent or pinched beyond its “minimum bend radius,” significant increase in IL will result.
Many of our customers report that contamination on the end-face is the #1 end-user complaint. Thankfully, contamination can be identified and controlled in the production environment. You may want to investigate the process your technicians follow to ensure end-faces are clean, and then shore up training as necessary.
Aramid yarns. These strength members are also known by the trade name Kevlar®. They provide tensile strength to the finished cable assembly (they are crimped to the connector body, so that any pull stress applied to the cable after it is connectorized will be taken by the aramid yarn, and not the fiber itself).
These high-strength synthetic fibers are notorious for dulling cutting blades. While this fabric can be cut with any sharp knife, razor blade, or scissors, they will easily dull such common off-the-shelf tools. Scissors designed specifically for cutting Kevlar should be used, and will provide much longer service life. They will need to be replaced or re-sharpened when they no longer cut easily.
When a manufacturer inspects an end-face, it is immediately capped afterward with a plastic dust cap, and (theoretically) this dust cap is never removed again until immediately before it is plugged into its final installation location by the installer. In theory, this ensures connectors will be sufficiently clean for installation.
However, there are a number of ways in which the end-face can (and do) become contaminated along the way:
When installing the dust cap, the manufacturer accidentally touches the end-face with the dust cap itself, leaving plastic mold-release grease or other contamination. Since the dust cap is never removed again by the manufacturer, it’s impossible to detect this.
In some poorly-designed dust-caps, the interior surface dimensions are such it permits contact with the end-face it is trying to protect, usually leaving a super-contaminated end-face.
During installation, dust caps are removed prematurely, while cables are still being organized/routed, and the end-face is exposed, and prone, to contamination.
There are a total of eight tips and considerations regarding freezing epoxy in FOC’s blog article, Ideas to adjust your epoxy process: Recommendations to reduce waste (and save money) in your fiber optic cable assembly process.
Important one to highlight: Consider implementing process controls, so operators have a clear understanding of all steps and labeling requirements.
There are a total of eight tips and considerations regarding freezing epoxy in FOC’s blog article, Ideas to adjust your epoxy process: Recommendations to reduce waste (and save money) in your fiber optic cable assembly process.
Here is an important one to highlight: Thawing epoxy is fast and easy.
The connector’s specifications dictate the quality of its performance and long-term reliability. That’s why it’s imperative to purchase high-quality connectors. Lower-quality connectors with lax tolerances can lead to optical performance issues such as high Insertion Loss, low Return Loss, and non-repeatable results. Lower-quality connectors can also invite a host of mechanical issues.
Whether you’re buying single mode connectors or multi-mode connectors, you want the best measurement tolerances possible for the following connector specifications:
Ferrule hole diameter – The ferrule is arguably the most important component in a fiber optic connector. For minimum Insertion Loss, you should use the tightest-tolerance ferrule hole diameter available.
Ferrule hole concentricity – The shape of the ferrule’s hole bore must be round. If not, you have ferrule hole eccentricity: an egg-shaped or oblong hole, which will not hold an optic fiber in perfect alignment and will degrade the performance of the connector. Ferrule hole concentricity is measured inside diameter to outside diameter (ID to OD).
Ferrule hole to outside diameter (OD) – The hole in the ferrule must be perfectly centered. If not, the fiber it holds cannot be properly centered and aligned. This is why it’s important to purchase ferrules with exacting tolerances.
At Fiber Optic Center, Inc., we encourage our customers to purchase quality connectors that offer the tightest tolerances for ferrule hole diameter, ferrule hole concentricity, and ferrule hole to outside diameter. When your fiber optic cable assembly house uses connectors that meet stringent measurements tolerances, you are positioned to build world-class fiber optic cable assemblies that deliver performance and long-term reliability.
Damaging inner materials when stripping any layer of the cable, is a ticking time-bomb. A fiber which has been scratched on the outer diameter may indeed function perfectly well for some time.
Stress points from which cracks in the glass can propagate over time, lead to (potentially) sudden and catastrophic failure of the cable assembly. This is why most Cable Assembly Houses will implement some method of evaluating newly-stripped fibers to help ensure no unseen damage has been done during the stripping process. A common such method is to perform a 45-degree bend test on the fiber where, if the fiber OD had been “nicked” by the stripping tool, this bend would cause the fiber to break at the scratch point. While this would then require re-stripping of the cable, it’s a much better problem to resolve than a fiber break in a deployed product!
There are a total of eight tips and considerations regarding freezing epoxy in FOC’s blog article, Ideas to adjust your epoxy process: Recommendations to reduce waste (and save money) in your fiber optic cable assembly process.
Here is an important one to highlight: Consider implementing process controls, so operators have a clear understanding of all steps and labeling requirements.
There are a total of eight tips and considerations regarding freezing epoxy in FOC’s blog article, Ideas to adjust your epoxy process: Recommendations to reduce waste (and save money) in your fiber optic cable assembly process.
Here is an important one to highlight:
The recommended length of time to keep epoxy frozen is typically 6 months or less. When freezing epoxy, expect about 50% of the room-temperature shelf life. For example, if the material’s data sheet states a room-temperature shelf life of 12 months, when you freeze the epoxy plan to use it within 6 months.
