Liquid discharge apparatus and liquid discharge module

A liquid discharge apparatus comprising:

• a head that includes a first connector and discharges a liquid;
• a substrate unit including a second connector fitted to the first connector and a third connector different from the second connector;
• and
• a relay substrate including a relay substrate front surface and a relay substrate back surface opposite to the relay substrate front surface, wherein
• a first cable through which a first voltage signal propagates is coupled to the relay substrate front surface,
• a fourth connector fitted to the third connector of the substrate unit is provided on the relay substrate back surface,
• the relay substrate includes a first side and a second side,
• the substrate unit includes:
• a first substrate including a first substrate front surface, a first substrate back surface opposite to the first substrate front surface, and a third side;
• and
• a second substrate including a second substrate front surface, a second substrate back surface opposite to the second substrate front surface, and a fourth side,
• the first substrate and the second substrate are electrically coupled to each other,
• the first side of the relay substrate is positioned along the third side of the first substrate,
• the second side of the relay substrate is positioned along the fourth side of the second substrate, and
• a normal direction of the relay substrate back surface intersects both a normal direction of the first substrate front surface and a normal direction of the second substrate front surface.