a flip - chip bonder fabricates an optical assembly by horizontally positioning a flexible portion of a substrate including a waveguide with the waveguide exposed at one end edge of the substrate ; bending a portion of the flexible substrate to place the waveguide exposed end in approximately a vertical position ; vertically positioning a bond head containing an optical component upon the waveguide exposed substrate edge to optically mate the optical component with the exposed waveguide ; and fixably mounting the optical component to the substrate edge .