Suspension substrate, suspension, suspension with head, hard disk drive, and method of manufacturing suspension substrate

A suspension substrate includes a metal substrate, a first insulating layer provided on the metal substrate, a first wiring line layer provided on the first insulating layer, a second insulating layer provided on the first insulating layer and the first wiring line layer, and a second wiring line layer provided on the second insulating layer. When a total of a thickness of the first wiring line layer and a thickness of the second insulating layer on the first wiring line layer is T1 and a thickness of the second insulating layer at a position where a surface of the second insulating layer is flat and which is away from the first wiring line layer by a predetermined distance is T2, T1−T2