Screw locking unit structure

A screw locking unit structure, comprising:

• a screw main body including a head portion, a stem portion extended from a lower side of the head portion, a first screw locking section located below the stem portion, and a second screw locking section located below the first screw locking section;
• the first screw locking section being externally provided with a first male thread and the second screw locking section being externally provided with a second male thread;
• and the first male thread and the second male thread being different in their tightening directions;
• an elastic element being externally fitted around the stem portion of the screw main body and located between the head portion and the first screw locking section;
• and
• a sleeve being integrally formed on or previously connected to an assembling interface;
• the sleeve including an upper end and internally defining an axial bore;
• the upper end being formed with an inner shoulder portion, and a length of the axial bore extended through the inner shoulder portion being formed with a female thread corresponding to the first male thread;
• and
• wherein when the screw main body is extended into the sleeve with the first male thread on the first screw locking section of the screw main body meshed with the female thread on the sleeve and two opposite ends of the elastic element elastically pressed against the lower side of the head portion of the screw main body and an upper surface of the inner shoulder portion, the screw main body can be held temporarily to the assembling interface before the latter is screw locked to a heat source;
• and the first and the second male thread with different tightening directions provide a function of stopping screwing automatically to prevent the second screw locking section extended through the assembling interface from being excessively screwed into the heat source.