Printed board unit for optical transmission and mounting method

摘要

It is an object of the present invention to enhance laser beam transmitting efficiency by accurately controlling an interval between a light emitting (light receiving) element ( 20 ) and an optical wave-guide substrate ( 1 ) without causing any fluctuation in the interval in a mounting structure of the light transmitting element in which the light emitting (light receiving) element ( 20 ) is mounted on the optical wave-guide substrate ( 1 ). When the light emitting (light receiving) element is joined to the sub-mount chip ( 4 ) and when the sub-mount chip ( 4 ) is joined to the optical wave-guide while the element is being directed to the substrate side, the sub-mount chip and the optical wave-guide substrate are joined to each other by the solder bump ( 6 ). A post ( 5 ) is arranged for regulating an interval between the light emitting (light receiving) element and the optical wave-guide substrate.