A method of manufacturing a lighting module comprises: mounting one or more light emitting diode (LED) packages on a circuit board to define a lighting unit; and injection overmolding the entire lighting unit except the one or more LED packages using a single type of overmolding material. A lighting module comprises: one or more LED packages mounted on a circuit board; and an injection overmolding sealing the circuit board, the injection overmolding not having openings corresponding to piece holding pins, the injection overmolding not covering at least a light emitting portion of the one or more LED packages.