Electronic control unit

A flexible circuit board assembly comprising a flexible circuit board having a first portion and a second portion separated by a bendable region and a substantially rigid substrate having a first portion and a second portion separated by a bend region. The rigid substrate has an inside surface and an outside surface. The first and second portions of the circuit board are affixed to the respective first and second portions of the substrate such that when the substrate is bent the bendable region of the circuit board must also bend. The bend region has a recess extending outwardly from the inside surface of the substrate, and the recess is sized to accept the bendable region of the circuit board around a single bend axis when the substrate is bent. The recess provides for a larger bend radius of the circuit board reducing stress.