Illuminated keyboard and backlight module thereof

A backlight module of an illuminated keyboard comprising:

• a circuit board having a top surface and a bottom surface opposite to the top surface, wherein the top surface has a plurality of key assembling regions, each of the key assembling regions has at least one stress release hole, and the at least one stress release hole is defined through the top surface and the bottom surface;
• and
• a plurality of light-emitting elements respectively disposed on the key assembling regions, wherein each of the light-emitting elements comprises a main body and at least one conductive portion connected to the main body, the at least one conductive portion is electrically connected to the circuit board, and the at least one stress release hole is adjacent to the at least one conductive portion of each of the light-emitting elements,
• wherein the at least one conductive portion comprises a first conductive portion and a second conductive portion, and the first conductive portion and the second conductive portion are respectively connected to two opposite sides of the main body;
• the at least one stress release hole comprises a first stress release hole and a second stress release hole, the first stress release hole and the second stress release hole are respectively at the two opposite sides of the main body, and the first stress release hole and the second stress release hole are respectively adjacent to the first conductive portion and the second conductive portion.