Surface distance

It defines the required clearance distance to maintain insulation between conductors. While creepage distance refers to the linear distance between conductors, creepage distance refers to the distance along the surface of an object such as the substrate on which the conductors are mounted, and it varies depending on the material of the object. The higher the insulation property of the material, the shorter the creepage distance can be. In many safety standards for electronic devices, the required creepage distance to maintain sufficient insulation is specified.