US Patent 9977204 Optical apparatus, printed circuit board

A printed circuit board includes a main body of laminate structures, and a metal piece. The main body has a first opening and a second opening. The metal piece is held by the laminate structures of the main body. The metal piece has a first face and a second face opposite to the first face. The first opening and the second opening respectively extend to the first face and the second face of the metal piece. A semiconductor optical device can be mounted on the first face of the metal piece, in the first opening.