Patent attributes
The present invention provides a fluid dynamic bearing device having high durability and capable of being produced at low cost. In the fluid dynamic bearing device, a housing and a disc hub are resin molded parts, and a thrust bearing gap is formed between an upper end surface of the housing and a lower end surface of the disc hub. In this case, the surfaces function as sliding portions temporarily in sliding contact with each other during operation of the bearing. A diameter of PAN-based carbon fibers blended as reinforcement fibers in the resin housing is 12 μm or less, and the blending amount is within a range of 5 to 20 vol %, thereby making it possible to prevent occurrence of flaws and wear in the sliding portions.