U.S. Pat. No. 7,049,559 discloses a PTC heating element including a substrate, electrodes, a PTC resistor, and cover material. The substrate is made of ceramics, insulated metal plate, or polyester film. The electrodes are formed on the substrate by printing and drying a conductive paste. The PTC resistor is formed on top of the electrodes by printing and drying a PTC composition ink. The substrate, the electrodes, the PTC resistor and the cover material are bonded by way of polyethylene hot melting resin.