Tried and true epoxy/polish and newer no-epoxy-no-polish methods are both getting better with age.
By Eric Leichter
Over the last 20 years, fiberoptic field connection techniques have steadily improved to create repeatable processes that result in quality terminations.
We will look at the two most common field-termination techniques and compare their benefits, but first, let’s review the basic components of a single fiber connector (Figure 1). The fiber is aligned within the center of the ferrule, and the ferrule of one connector mates up with that of another. The spring force ensures that the ferrules obtain physical contact so that the fibers touch. The boot helps maintain bend radius and protects the fiber, while the body gives the connector its shape and a method to latch into an adapter port.
 FIGURE 1. In a typical single-fiber termination, the spring force of the connector ensures that the ferrules obtain physical contact so that the fibers touch. |
The standard method to terminate connections has been epoxy-and-polish (E/P). In this method, you use a syringe to inject a curing agent into the connector ferrule, then remove the coating from the field fiber and push it through the ferrule until it seats against the ferrule holder.
A slow cooker
The original curing agent was heat activated and the connector would sit in an oven for six or more minutes until cured. That curing method fell out of favor in the field due to the time and mass of portable ovens required. Heat-cured epoxies are now mostly limited to cable assembly houses where an assembly line process can be created.
Today, installers are using an EZ anaerobic adhesive agent that does not require an oven, heat lamp, or other powered device. By eliminating the requirement for power, and the duration needed to warm up the oven and cure the epoxy, the anaerobic method has become the most common field termination method today. A primer is often used to speed up the curing process, which is now down to 45 seconds.
Additional improvements have been made to the polishing procedures to further simplify and speed up the termination process. Polishing can be a complicated process and, historically, different papers and steps were required for each connector type. This year, CommScope streamlined the process so that the same papers and basic polishing steps are used for all three common connector styles (LC, SC, and ST). Beyond making it easier to polish these connectors, it will also make it easier to order and stock these items.
The process was simplified through an improvement to the LC connector. A standard version arrived to the installer with a “flat” ferrule that had to be polished into a dome. The CommScope version has a domed ferrule known as a “pre radiused” endface (Figure 2). Creating the dome in the factory eliminates the polishing step previously required to create this dome.
 FIGURE 2. A pre-radiused enface is designed to produce a better polished connector with fewer steps and improvement to the polishing process. |
As shown in the table (below), the polishing times are approaching those of the newer no-epoxy, no-polish connectors. The benefits of the new polishing process include:
- One consumable kit for all three connector types;
- Fewer sheets or polishing paper and no pads or spacers required;
- Less inventory of termination materials to maintain;
- More efficient use of consumables;
- Fewer steps for pre-radiused LC connectors;
- Improved end-face geometry;
- Consistently low insertion loss.
E/P vs. NENP
An alternative technology has come along to challenge the reliable epoxy- and-polish method. These connectors are all based upon the use of a fiber stub that is inserted into the ferrule, cured into place, and polished in the factory. The termination is created by cleaving a field fiber and creating a mechanical splice.
These “no-epoxy and no-polish” (NENP) connectors give you the ability to terminate a connector without the use of consumables or timely curing and polishing steps.
NENP technology has been available since the early 1990s and, as a new technology, has had some growing pains; manufacturing of this connector is not as easy as for a standard E/P product. The polished endface, the internal fiber stub cleave, the quality of the splice and the cleanliness of the internal components make the NENP connectors a challenge to manufacture.
Over 15-plus years, however, the technology has matured and is now a fairly reliable product that can be used in typical enterprise applications. CommScope has released the Qwik LC, Qwik SC, and Qwik ST connectors to provide customers a quality NENP connector that can be used as part of a complete SYSTIMAX or Uniprise solution.
When comparing the two technologies for performance, the NENP product is at a disadvantage because of its mechanical splice; there will always be a higher typical loss compared to an E/P, which does not have a splice to create loss.
For customers requiring very low losses (0.1 – 0.2 dB average), the E/P product is highly recommended. Additionally, E/P connectors are generally less expensive because the product is a relatively simplistic tube that does not contain splice or fiber stub components.
The NENP, meanwhile, has its own advantages, including a reduction in consumable costs and installation time. NENP connectors are best suited for indoor or controlled environments and can be used for behind the wall (BTW) applications, rapid repairs or in limited spaces where polishing may be difficult (i.e., fiber to the desk).
You can calculate the potential savings due to reduction in these two costs versus the increase in connector cost; generally, the E/P connector will provide the lower cost solution; coupled with the better performance, the E/P connector is the recommended connector type for many field installation solutions. But customers who have a strong preference for NENP technology can, for example, choose the new Qwik LC, Qwik SC, and Qwik ST connectors. (See sidebar, “Taking a Qwik-look,” above.) Remember that the use of factorymade patch cords are receommended for the best all-around performance.
Two good choices
The technology for connector termination has improved greatly over the years, and there are now two viable options for connectorization within the field. While the epoxy-and-polish connector has been a solid termination method that produces great performance at a reasonable cost and will continue to be used for many years, the newer no-epoxy, no-polish termination methods are gaining popularity because of their reduced set-up and installation time, as well as the elimination of consumables.
It is good to have quality choices!
ERIC LEICHTER is training manager at CommScope Enterprise Fiber Solutions (www.commscope.com).
Taking a Qwik-look...
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As a no-epoxy no-polish (NENP) solution, CommScope claims its Qwik Connectors offer:
- Less overall installer training;
- No work surface required;
- No visual fault locator (red laser light) required for accuracy;
- Performance results equal to that of field-polished connectors;
- Controlled end-face geometry for better insertion loss and return loss performance;
- Precision cleaving tool for consistent angles;
- Small tool kit that terminates ST, SC and LC connectors;
- No consumables needed for polishing;
- No bonding agents needed;
- Installation in typically less than 11⁄2 minutes per connection;
- 62.5-μm, 50-μm and singlemode fiber types;
- ST, SC and LC connectors.
