A method of making an electronic circuit device includes expelling air from a gap between a circuit board and an electronic element mounted on only a first side of the circuit board by filling the gap with a filling member, placing the circuit board in a mold cavity such that a second side of the circuit board is held in close contact with an inner surface of the cavity. The method further includes encapsulating the circuit board with a resin material by injecting the resin material into the cavity.