| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve accuracy about the impedance matching of a signal conductor on a main surface and an upper surface of a sub mount substrate. <P>SOLUTION: A sub mount substrate 12 includes an insulating substrate 121, and a signal conductor 122 and a ground conductor 12 provided on the insulating substrate 121. The insulating substrate 121 includes a main surface 121a including a mounting area 121a<SB POS="POST">1</SB>of an optical semiconductor element 2, a back surface 121b provided on the opposite side of the main surface 121a, and an upper surface 121c. The back surface 121b includes a first surface 121b<SB POS="POST">1</SB>facing the main surface 121a at the back side, and a second surface 121b<SB POS="POST">2</SB>facing the upper surface 121c at the back side; and has a recessed portion 121e defined by at least the first surface 121b<SB POS="POST">1</SB>and the second surface 121b<SB POS="POST">2</SB>. The signal conductor 122 is provided from the main surface 121a to the upper surface 121c. The ground conductor 123 is provided on at least the first surface 121b<SB POS="POST">1</SB>and the second surface 121b<SB POS="POST">2</SB>of the back surface 121b. <P>COPYRIGHT: (C)2012,JPO&INPIT |
