PROBLEM TO BE SOLVED: To provide a lead-free solder alloy which can suppress crack progress of a solder joint even under such a severe environment that a difference in temperature is large and vibration is loaded, and can suppress crack progress in the interface vicinity between an electronic component and the solder joint even when solder joining is performed by using an electronic component not subjected to Ni/Pd/Au plating and Ni/Au plating, and to provide an electronic circuit board having a solder joint formed by using the lead-free solder alloy and an electronic control device.SOLUTION: A lead-free solder alloy contains 1 wt.% or more and 4 wt.% or less Ag, 1 wt.% or less Cu, 3 wt.% or more and 5 wt.% or less Sb, 0.01 wt.% or more and 0.25 wt.% or less Ni, and with the balance being Sn.SELECTED DRAWING: Figure 1
