Luminous keyboard and backlight module thereof

A backlight module comprises:

• a spacer, having at least one spacer hole, an outer edge gap being defined outside an outer edge of the spacer;
• a lower substrate, disposed below the spacer;
• at least one light source, disposed on the lower substrate and located within the spacer hole;
• and
• a shielding structure, disposed outside said light source to at least partially block light provided by said light source from emitting towards the outer edge gap;
• wherein an inner adhesion layer and an outer adhesion layer are disposed on a flat surface of the spacer, and at least one air gap is located between the inner adhesion layer and the outer adhesion layer;
• wherein the inner adhesion layer, the at least one air gap and the outer adhesion layer are aligned in series toward the outer edge gap to jointly form the shielding structure to reduce partial light of the light source from leaking out of the outer edge gap.