FIG. 1 shows the structure of a conventional spindle motor. The spindle motor 1 of the prior art mainly comprises a rotor 11, a stator 13, a circuit board 15 and a mounting plate 17, wherein the circuit board 15 includes a plurality of electronic components 15a and electric contacts 15b. The spindle motor 1 must use an external connecting piece 3 such as a cable to electrically connect with the plural electric contacts 15b, so that electric signals can go through the external connecting piece 3, the plural electric contacts 15b and the electronic components 15a for changing the electromagnetic fields of the stator 13 to rotate the rotor 11. By the fact that the circuit board 15 is made to the scale of a large area in pursuance of the scope covered by the rotor 11 and the stator 13, and it allows a part thereof with the electric contacts 15b to protrude to quite a degree, however, the circuit board 15 of the conventional spindle motor 1 of such a structure occupies quite a large space, therefore, the conventional spindle motor 1 of such a structure is hard to meet the requirement of being light, thin, and small.
In view of the above stated defects of the prior art, the inventor of the present invention tried hard to figure out an improvement and thus developed a spindle motor for a slim optical disk apparatus; the improved spindle motor of the present invention has the feature of being light, thin, and small, so that miniaturization of optical disk apparatuses can be more easily realized.