| 摘要 |
PURPOSE: To obtain an optical recording medium which has sufficient welding strength and is free from the warpage of a substrate and the degradation in double refraction and a production method thereof. CONSTITUTION: A hub 5 having a welding rib 6 is ultrasonically welded to the substrate 2 formed with a recording layer, etc., 3. This optical recording medium is so formed that the relation of the following equation holds between the height L of the welding rib of the hub and an ultrasonic welding depth D: 0.12mm3D<=(L-0.05mm). |
