Check the internal method of fiber optic connector

The cross-section questions of fiber optic connectors are answered here. How many ways do we have to look inside the connector? There are currently three methods of looking inside a fiber optic connector:

(1) Non-destructive X-ray

(2) Lossless sonar

(3) Destructive cross section

These methods help engineers determine the causes and effects of fiber optic connector failures and monitor the connector assembly process. All three methods have advantages and disadvantages, which are highlighted here:

The high cost of X-ray and sonar inspection services adds $1,000 to the cost of each fiber optic connector, and $300-600 per connector for destructive cross-sections. X-ray and sonar are much more invested than destructive cross-section equipment. Better visibility into internal details of how connectors are assembled, and better detail for destructive cross-sectional failure analysis.

Although x-rays and sonar are non-destructive, they can only provide a limited view of the interior, revealing key features of the bare fiber within the internal connector. This includes epoxy wicking through connectors, under/over epoxy application, air bubbles and scratches/cracks in the fiber Comprehensive failure analysis to prevent persistent problems and defects in connectors.

This unique cross-section service is provided to identify and isolate issues related to fiber terminations that would otherwise be invisible. The process begins with metallographic analysis of fiber optic connectors, requiring hours of vacuum drying, followed by vacuum fixing of the samples with a slow-curing, low-expansion epoxy.

Samples of these packages were then manually polished to maintain precise planarity, depth and co-planarity with the ceramic holes to provide the best vantage point for final inspection. FOC then provides failure mode explanations and suggests failure causes or sources. Photographic documentation of various magnifications, lighting techniques, and microscopes are included to illustrate this analysis.

Connector A

Fiber optic connector inspection

Observations: This particular connector has multiple cracks inside the ceramic ferrule (Photos A.1-A.3) and a considerable length of fiber is missing. See photos A.2 and A.3. From the location of the missing fiber, it appears that a portion of the fiber was present during the assembly process prior to heat curing. During the assembly process (during insertion of the fiber), this particular fiber was subjected to a lot of shock. I've seen ferrules with a tight fit before, and when trying to push the fiber through the hole, the fiber cracked and snapped inside the ceramic ferrule. Not sure exactly what aperture this is, it appears the cause of the failure has something to do with how the fiber is inserted into the ferrule.

Connector B

Fiber optic connector failure

This connector has (1) an apparent fiber break at the start of the ceramic internal chamfer (Photo B.2). I did notice more "epoxy shrinkage" than usual on the inside. This shrinkage during heat curing causes the fiber to break, where the cut fatigues the fiber, and the stress of heat curing and shrinkage actually separates the fiber at that location. The remaining fiber trapped inside the ferrule shaft acts as an anchor point. This is the most common problem caused by fiber nicking caused by improper use of mechanical strippers or misaligned blades.

Connector C

inside the connector

Observations: There is a large gap between the end of the stripped bumper area and the fracture point (inside the internal chamfer of the ceramic ferrule). Also noticeable is the shrinkage of the epoxy, which is very noticeable on chamfers. It appears that the epoxy inside the ferrule cures first and acts as an anchor point during the heat cure. When thicker areas of epoxy cure, accidental backward movement of the fiber can pull and break the fiber, creating a visible gap; or rapid contraction of the epoxy can pull everything and "separate" from the anchor fiber inside the ferrule ".