Display device and manufacturing method of display device

A display device comprising:

• a display module comprising a base substrate, the base substrate having a display area and a non-display area adjacent to the display area, and a first pad on the base substrate and overlapping the non-display area;
• and
• a circuit board comprising a first board and a second pad on the first board, the second pad electrically contacting the first pad, wherein the second pad is a single layer consisting of a single material comprising copper, wherein the second pad is directly on the first pad, and wherein the circuit board further comprises a third pad separated from the second pad on a plane of the circuit board and electrically connected to the second pad;
• a driving circuit board comprising a second board and a driving pad on the second board, wherein the driving circuit board is electrically connected to the third pad;
• and
• an anisotropic conductive film electrically connecting the third pad and the driving pad, the anisotropic conductive film comprises:
• an adhesive film between the first board and the second board;
• and
• conductive particles in the adhesive film and configured to electrically connect the third pad and the driving pad,
• the third pad comprises:
• a second metal layer on the first board;
• and
• an auxiliary metal layer on the second metal layer and configured to electrically contact the conductive particles,
• wherein the second metal layer is composed of the same material as that of the second pad.