Fiber optic patch cords are one of the simplest elements in any optical network, consisting of a piece of fiber optic cable with a connector on each end. Despite its simplicity, the patch cord can have a strong effect on the overall performance of the network. The majority of problems in any network occur at the physical layer and many are related to the Fiber Optic Patch Cord quality, reliability, and performance. Therefore, using patch cords that are more reliable helps reduce the chance of costly network downtime.
Network designers would prefer components with a history of proven long-term performance. However, since optical networking is a relatively new technology, there is no significant long-term data for many components. Therefore, designers must rely upon testing from the component manufacturer or supplier that can simulate this history and assure the quality and reliability over the life of the network. This paper discusses the importance of quality, reliability, and performance as they relate to industry standards and manufacturing practices. The performance of the patch cord is also studied using a “perfect patch cord” and polishing observations as tools to understand patch cord principles.
Patch cord reliability is guaranteed not only by using quality components and manufacturing processes and equipment, but also by adherence to a successful Quality Assurance program 4). While patch cords themselves are typically tested 100% for insertion loss and return loss, if applicable, there are many other factors that need to be monitored to insure the quality of the patch cord.
One of the most important factors is the epoxy. Epoxies typically have a limited shelf life and working life, or “pot life.” This information is readily available from the manufacturer. It is absolutely necessary that both of these criteria be verified and maintained during manufacture. Epoxy beyond its expiration date needs to be discarded. Chemical changes affecting the cured properties of the epoxy can occur after this date. This date can also be dependent on storage conditions, which need to be observed.
Most epoxies used in fiber optic terminations are two-part epoxies and, while they cure at elevated temperatures, preliminary cross-linking will begin upon mixing. Once this has started, the viscosity of the epoxy can begin to change, making application more difficult over time. The epoxy can become too thick to fill the ferrule properly and too viscous to enable a fiber to penetrate, causing fiber breakage.
Mixing two-part epoxies introduces trapped air, or “bubbles”, which is injected into the connector. This trapped air introduces inconsistency in the cured epoxy, leading to a high risk of mechanical failure. The trapped air, or bubble count, must be minimized.
Many of the tooling used in patch cord assembly also has periodic maintenance and a limited tool life. This includes all stripping, cleaving and crimping tools. Most stripping tools, whether they are hand tools or automated machines, can be damaged by the components of the cable, most notably the aramid yarn strength members. Buffer strippers will dull with prolonged usage, increasing the likelihood that they will not cleanly cut the buffer. This can lead to overstressing the fiber when the buffer is pulled off. When a cleaving tool wears out and a clean score is not made, it is almost impossible to detect during manufacturing. However, the result could be non uniform fiber breakage during the cleave, which can result in either breaking or cracking the fiber below the ferrule endface. In this instance, the connector will have to be scrapped. Even crimp tools require periodic maintenance to insure the proper forces and dimensions are consistent. Crimp dies also have a tendency to accrue epoxy build-up, which can affect the crimping dimensions and potentially damage the connector.
The integrity of the incoming materials and manufacturing processes, once specified, needs to be adhered to all the appropriate guidelines and procedures. The importance of these materials not only has a strong influence on product reliability, but also on product performance.
Fiberstore manufactures and stocks fiber optic patch cables. Our stock cables feature FC/PC, FC/APC, and SMA connectors, and use single mode (SM),or multimode (MM) fiber.For example, LC to LC fiber patch cable, multimode fiber patch cables, single mode fiber SC to LC. We offer ar-coated cables for fiber-to-free space use, lightweight cables for optogenetics, high-power cables, and many other specialty fiber patch cables from stock. We also offer multimode fiber bundles, as well as custom patch cables with 24 hour turnaround on many orders. If you do not see a stock cable that is suitable for your application, please contact us. Our extensive experience with fiber patch cables enables us to offer a custom patch cable service that can ship on the same day, without a minimum order quantity.