A circuit board includes an insulating portion and a pattern portion on the insulating portion. The insulating portion includes a first insulating region and a second insulating region outside the first insulating region and spaced apart from the first insulating region with a separation region therebetween. The pattern portion includes a first pattern portion for signal transmission and a second pattern portion including a dummy pattern separated from the first pattern portion. The first pattern portion includes a first terminal portion on the first insulating region, a second terminal portion on the second insulating region, and a connection portion on the separation region and connecting between the first terminal portion and the second terminal portion. The second pattern portion includes a second-first pattern portion on the first insulating region and a second-second pattern portion on the second insulating region and separated from the second-first pattern portion.

A bus bar assembly includes a first circuit board that includes a first circuit on at least one surface of the first circuit board. A second circuit is provided on a surface of the first circuit board and electrically connected to the first circuit board. A second circuit is printed on two surfaces of the second circuit board.