What must the minimum electronegativity difference be between two atoms to classify a bond as polar covalent?

Electronegativity Difference

The measure of the ability of an atom in a molecule to draw bonding electrons to itself compared to another atom in the molecule, determining the polarity of the bond.

Polar Covalent

A type of chemical bond where a pair of electrons is unequally shared between two atoms, leading to a distribution of electric charge across the molecule.