In the 1990’s FC/APC connectors were essential to high-bandwidth systems requiring minimal return loss prominently used in CATV networks and other high-sensitivity applications. Transitioning into the early-2000s, SC/APC connectors gained popularity for their ease of installation attributed to their push/pull design. As we navigate the landscape of modern networks and look ahead, there is a growing need to minimize the interconnect form factor sizes to make room for more bandwidth. This shift is primarily driven by the escalating costs associated with data center operations and the urgent need to optimize space to support the expanding network demands. In particular, those demands are brought on by advancements in AI Technologies.
While MPO and MTP connectors are very popular the necessity for single fiber APC simplex and duplex connectors remain, especially those with compact form factors for efficient interconnectivity to equipment and panels. Among the emerging preferences, LC/APC and MU/APC connectors stand out for their reduced size compared to larger counterparts like SC/APC, positioning them as the dominant choice in today's evolving network infrastructure.
APC Interconnect Type Products: Problems and Solutions
End-Face Angle Forming: Because APC connectors have an angled cone type end-face with a spherical radius, there is an inherent shift in the actual measured angle, necessitating adjustments during the forming and polishing process to achieve the precise eight-degree angle. For instance, cone ferrules require a fixture angle of 8.3 degrees to obtain an effective angle of 8.0 degrees. Additionally, it is critical to adhere to tolerances maintained within +/-0.25 degrees to minimize excess loss. It is imperative that test cables are certified and procured from reputable manufacturers to guarantee compatibility and prevent intermatability issues throughout the system.
Key Error (Apex Offset): Because of the intricacies involved in manufacturing APC interconnect products, it is imperative that all internal and external keying components adhere to strict tolerances. The cumulative effect of tolerance stacking will lead to key error, becoming a significant factor affecting insertion loss and contributing to excess loss across all APC interconnect designs. However, maintaining consistency in high-volume production of injection-molded and machined parts can be challenging to maintain. Again a reputable connector manufacturer must be used so this is a non-issue!
Ferrule Concentricity and Bore Size: The ferrule is the most critical component in any interconnect design. This is because its tolerances are maintained with an order of magnitude greater than all other components. It is advisable to select a reputable company that conducts comprehensive testing of bore size and concentricity on all products. This ensures that potential issues are identified before fibers and ferrules are permanently bonded, preventing the discovery of inferior performance after assembly
Non-angularity of the Ferrule's ID Bore Hole and the End-Face: This issue, which we are prepared to reveal to the global market, may represent one of the final yield challenges that numerous ceramic ferrule manufacturers either choose not to address or fail to comprehend.
It has been observed that when the ferrule undergoes polishing to approximately 0.1mm to create the APC Angle, the end-face ID bore hole shifts resulting in a non-concentric error of up to 0.003mm on a percentage of the ferrules.
Precision Fiber Products (PFP) has been a key player in the manufacturing of APC connectors for over two decades. During this time we have been aware of yield issues associated with APC interconnect products. Initially, these issues were deemed acceptable given the significant benefits in return loss performance. However, we now recognize the need to improve yields and further reduce costs. Achieving this objective will require ceramic ferrule manufacturers to improve their processes. Our engineering team has conducted comprehensive evaluations of major ferrule manufacturers across Japan, China and various other regions worldwide. We have discovered that this issue is prevalent among most of them.
Test Results
Measuring concentricity, especially after the angled end-face has been formed, presents a challenge for many of us. Therefore, in all of our tests we opted to assess the concentricity both before and after removing 0.1mm of material from the end-face, utilizing a flat ferrule fixture for simplicity and accuracy.
PFP's dedication is underscored by our engineering team's thorough comparative testing. This testing is done before and after the process of removing the 0.1mm formation from the end-face on samples from three leading ferrule manufacturers. In this way we can compare the cause and effect of creating the angle.
The following are the results of these tests from 3 leading ferrule manufacturers:
Conclusion
Precision Fiber Products (PFP) has conducted a comprehensive analysis of several leading ceramic ferrule manufacturers to examine the impact of material removal in the creation of the angled end-face. The study reveals that the removal of 0.1mm of the material adversely affects the concentricity due to issues with the inner diameter (ID) hole’s angularity near the end-face arising during the manufacturing process of ceramic ferrules
Our most sincere apologies for any redundancy, but it is crucial to emphasize the importance of procuring interconnect components from a well-regarded and knowledgeable source. Particularly one that specializes in APC styles and understands the intricacies of engineering and manufacturing. We encourage engineering teams worldwide to conduct sample testing on their APC inventory, to ascertain the presence of yield issues or substandard connectors. If you do not have a way to test concentricity, we invite you to collaborate with us. We offer complimentary concentricity testing services to confirm the quality of your components. Our sincere desire is to improve quality and reduce costs for our industry.