Effect of intermediate layer on weldabilities has been studied in steel-plastic-steel laminates. Acceptable welds can be obtained, when the electric resistance at the first cycle of spot welding is less than 0.6 mΩ. To obtain the suitable resistance, the control of thickness of the intermediate layer, diameter of electric-conductive particles, ratio of the thickness and diameter, and content of the particles are important. The intermediate resin layer is harmful of arc welding and laser welding ; thinner layer is preferable.
