An ultrasonic welding method includes: arranging the contact element and a first conductor portion of a first conductor between an anvil and a sonotrode; welding the contact element to the first conductor portion, where the anvil and the sonotrode are moved relative to each other in opposite directions to press the first conductor portion and the contact element against each other, and the sonotrode vibrates with ultrasonic vibrations; arranging the contact element and a second conductor portion of a second conductor, which is made of a different electrically conductive material than the first conductor, between the anvil and the sonotrode so that the second conductor portion lies between the first conductor portion and the sonotrode; welding the first to the second conductor portion.