Method of welding laminates each having the structure of metal layer/thermally softenable insulating layer/metal layer

A method of resistance-welding two laminates each having a basic structure of a metal layer/a thermally softenable insulating layer/a metal layer, comprising the steps of:

• preparing laminates in which the thickness of each metal layer falls within a range between 0.02 and 0.5 mm and the ratio of the total thickness of the two metal layers of each laminate to the total thickness of the laminate falls within a range between 1/3 and 2/3;
• holding a pair of electrodes for resistance-welding on opposite sides of overlapped portions of the two laminates, heating the overlapped portions to a temperature not lower than the softening temperature of the insulating layers by electrodes which are heated by heaters arranged around the electrodes to a temperature higher than the softening temperature of the insulating layers, thus softening the insulating layers, and applying pressure to the pair of electrodes at the overlapped portions to thereby bring the metal layers of the two laminates into contact with each other;
• and
• supplying power to said pair of electrodes while said metal layers of the two laminates are in contact with each other.