Ferrule fabrication for the MT-type optical fiber connector using the microinjection process

This study presents a novel design to fabricate the hole array mold parts for 12 ports of the MT-type ferrule using a LIGA process. This fabrication technique can reduce the positioning error efficiently when making the mold assembly. The present design also makes replacing the mold parts convenient. The hole fabrication consists of a single x-ray exposure and development process, Ni-Co (nickel-cobalt) electroforming, and microinjection molding for a fast-curing epoxy liquid compound. Compared to conventional transfer molding technology, the present method for microinjection reduces the cycle time to about 35 s and saves on raw material. The 12 ports in the MT-type optical fiber ferrule were designed using the JIS C5981 and IEC60874-16 specifications. The diameters of the fiber holes had errors of ≤1 νm, and their position was smaller than 2 νm; these dimensions conform to the single-mode specifications. The proposed LIGA technique has been proven to be effective in reducing the positioning error in mold assembly construction. For the single-mode MT-type connector in the present study, the mean insertion loss (IL) was lower than that shown in the reported literature while the mean return loss (RL) was higher. The uniformities exhibited in IL and RL are much better than those previously reported.