Captive screw

A captive screw, comprising:

• a sleeve, comprising:
• a cylindrical body portion, having an inner surface, wherein the inner surface of the body portion surrounds and forms an accommodating space;
• and
• at least one positioning protrusion, protruding from the inner surface of the body portion and forming a channel, wherein a diameter of the channel is less than a diameter of the accommodating space;
• and
• a screwing member, comprising a head portion, a neck portion and a threaded portion, wherein the neck portion connects the head portion and the threaded portion, a diameter of the neck portion is less than a diameter of the head portion and the diameter of the channel, the neck portion passes through the channel, and the head portion and the threaded portion are located on two opposite sides of the at least one positioning protrusion, respectively;
• wherein the threaded portion comprises a wider section and a narrower section, the wider section is connected to the neck portion, the narrower section is directly connected to the wider section, the wider section and the narrower section each has a threaded profile with a step transition therebetween, the diameter of the channel is less than a major diameter of the wider section, and the diameter of the channel is greater than or equal to a major diameter of the narrower section and a minor diameter of the wider section.