Optical module assembly, optical module, package for optical module and flexible printed board

A package for an optical module comprising:

• a side wall;
• and
• a substrate provided through the side wall in a first direction, the substrate including
• a first wiring layer that is externally exposed, the first wiring layer including
• a first signal terminal extending along the first direction,
• a second signal terminal extending along the first direction, and
• a first ground terminal extending along the first direction, and being provided between the first signal terminal and the second signal terminal when viewed in a second direction perpendicular to the first direction,
• a second wiring layer disposed under the first wiring layer, the second wiring layer including
• a first ground pattern extending in both the first direction and the second direction, and
• a first insulating layer disposed between the first wiring layer and the second wiring layer, and
• a groove extending along the first direction, the groove being filled with a metal,
• wherein the groove is provided within the first ground terminal, in a plan view,
• wherein the first insulating layer is free of the groove, and
• wherein the first ground terminal is electrically coupled to the first ground pattern through the metal of the groove.