Method of producing foil formed member, method of producing wiring substrate, and method of producing integrated circuit

A method of producing a wiring substrate, comprising:

• preparing a substrate on which a toner image of a toner, in which a volume fraction of particles having a particle diameter of 16 μm or more is less than 1%, is formed;
• and
• forming a foil image on the toner image of the substrate,
• wherein the toner image is a plastic toner image having plasticity, which is formed by a plastic toner,
• in the forming, a foil is pressed against the substrate at a temperature of 70 or lower, to form the foil image on the plastic toner image of the substrate, and
• the plastic toner satisfies Expression (1):
• 20° C.≤T(1 MPa)−T(10 MPa) (1)
• wherein, in expression (1), T (1 MPa), represents a temperature at which a viscosity of the plastic toner becomes 104 Pa·s under an applied pressure of 1 MPa, and T (10 MPa) represents a temperature at which a viscosity of the plastic toner becomes 104 Pa·s under an applied pressure of 10 MPa.