Patent ID: 8310833

Claim:
An electronic circuit device comprising: a circuit board having first and second sides opposite each other; an electronic element mounted on only the first side of the circuit board; and a resin casing configured to encapsulate the circuit board and the electronic element, wherein: the second side of the circuit board is exposed to one side of an outer surface of the casing to define part of the one side of the outer surface of the casing, the entire one side of the outer surface of the casing including the exposed second side of the circuit board is a machined flat surface, the circuit board includes a first base and a second base joined to the first base, the first base and the second base being joined together through a prepreg layer, the first base has trace patterns on both sides and defines the first side of the circuit board, and the second base has no trace pattern and defines the second side of the circuit board.