Common defects and causes of fiber optic connector polishing

Fiber optic connectors are very important passive optical components in fiber optic systems, and their performance directly affects the quality and reliability of fiber optic transmission. To ensure the performance of fiber optic connectors, it is necessary to perform fine grinding and polishing on the connectors, which is crucial for improving their optical performance. However, various defects may occur during the research and development process, which can seriously affect the performance of fiber optic connectors. The following is a detailed analysis of common defects and their causes during the polishing process of fiber optic connectors.
Splitting fibers
Fiber breakage refers to the phenomenon of deep fracture of optical fibers partially or completely, with a smooth and uniform fracture surface, displayed as large black blocks on the end inspection instrument. The main reasons for fiber breakage are as follows:
Protective glue problem: The protective glue on the plug head is too large, too thick, or too small, and when ground, the whole piece falls off, causing excessive local stress on the optical fiber and resulting in brittle fracture.
Grinding machine speed: If the grinding machine speed is too fast or the grinding process is not smooth, the stress on the optical fiber is too high and uneven, ultimately leading to fiber breakage.
Black and white dots
Black and white spots are actually pits on the fiber end face, with black spots being deep pits and white spots being shallow pits. The reasons for the occurrence of black and white spots include:
Insufficient cutting force: The cutting force of D1 grinding paper is insufficient, or the previous process is too rough to repair the damage to the fiber end face.
Impurity problem: There are large particles of impurities in D1 or polishing pads, which damage the optical fiber during the grinding process and form pits.
Coating detachment: D1 or polishing pad coating detachment, mixed between the plug and the grinding pad, causing the optical fiber to have pits due to excessive local stress.
Unstable operation of grinding machine: The grinding machine operates unstably or impurities are mixed in during the grinding process, causing excessive local stress on the optical fiber and forming pits.
Black border
Black edge refers to the dark ring appearing at the connection between the optical fiber and the ceramic, which is caused by the deep breakage of the fiber edge and epoxy adhesive, resulting in blackening due to differences in reflection. The reasons for black borders may include:
Excessive grinding force: D1 has excessive grinding force, causing cracks in the fiber edge and epoxy adhesive, which cannot be repaired by polishing.
Grinding blade powder detachment: D1 grinding blade powder detachment is severe, causing rolling grinding and resulting in fiber edge and epoxy adhesive cracking.
Grinding force too weak: D1 grinding force is too weak, and the edge pits caused by the previous grinding cannot be completely repaired, and polishing cannot be repaired either.
Grinding machine speed too fast or pressure too high: Grinding machine speed too fast or pressure too high may cause damage to the fiber edge and epoxy adhesive.
Burnt
The burning phenomenon refers to the adhesion of a thick layer of material (debris and adhesive mixture) on the end face of the plug-in core, making the fiber end face almost invisible. The causes of burning may include:
Excessive grinding pressure: The grinding pressure is high, and the hardness of the rubber pad is high, resulting in a decrease in abrasive on the surface of the grinding plate coating and a decrease in cutting force.
Low softening point of the coating: The coating has a low softening point, and under the action of grinding force, the adhesive becomes sticky, resulting in a large amount of debris adhering to the surface of the coating, which eventually transfers to the end face of the plug, causing burning phenomenon.
scratch
Scratches refer to linear damages that appear on the end face of the plug, which are divided into deep scratches (black lines) and shallow scratches (white lines). The reasons for scratches may include:
Impurities in grinding disc: There are abnormally large particles such as impurities in the grinding disc, or the surface of the grinding disc is uneven, which causes local stress on the optical fiber and large cutting depth, resulting in scratches.
Low grinding pressure: With low grinding pressure, the grinding machine operates unstably, resulting in excessive local stress and deep cutting, leading to scratches.
Grinding blade cutting phenomenon: The grinding blade has a cutting phenomenon, with a hard and uneven surface, resulting in excessive local stress and a large cutting depth, causing scratches.
Abnormal polishing pad: Silicon dioxide particles agglomerate in the polishing pad, or the polishing pad has no cutting force, resulting in scratches.
The research and development process of fiber optic connectors is crucial to ensure the performance of fiber optic transmission systems. In the process of grinding and polishing, various parameters must be strictly controlled, such as grinding pressure, grinding machine speed, and selection of grinding medium, to avoid the occurrence of the above-mentioned defects. At the same time, strict quality control of grinding and polishing pads to ensure their surfaces are free of impurities, smooth, and have appropriate cutting force is the key to ensuring the quality of fiber optic connectors. Through meticulous operation and strict quality control, defects in the polishing process can be effectively reduced, and the performance and reliability of fiber optic connectors can be improved.