Stepping motor and electric motor module

A stepping motor comprising:

• a housing;
• a rotating shaft rotatably connected to the housing:
• a magnetic steel fixed to the rotating shaft;
• and
• a winding assembly received and fixed to an inner side surface of the housing and spaced
• apart from and surround an outer side of the magnetic steel;
• wherein the winding assembly comprises:
• an annular bobbin coaxial with the housing;
• two claw poles spaced apart from each other along an axial direction of the rotating shaft;
• and
• a coil wound around an outer peripheral side of the bobbin;
• wherein the two claw poles extend into the bobbin and are spaced apart from and opposite to the magnetic steel;
• wherein the bobbin comprises a side wall around which the coil is wound, the side wall comprising:
• an arcuate portion having a first thickness;
• and
• a first planar portion having a second thickness less than the first thickness,
• wherein the first planar portion comprises an o9uter surface in contact with the coil, the outer surface being planar.