It should be noted that if the thickness of the first conductive layer 110 is too small, the thicknesses of the first extension electrode and the second extension electrode are also small, and correspondingly, the depths of concave spots in the first extension electrode and the second extension electrode are small, which does not favor the increase in soldering strength. If the thickness of the first conductive layer 110 is too large, the thicknesses of the first extension electrode and the second extension electrode are also too large, and the resistance between the first contact electrode 106 and the second contact electrode 107 and the driving circuit is easily increased. It is easy to cause the aspect ratio of the concave spot to be too large and increase the filling difficulty of the solder. Correspondingly, the thickness of the first conductive layer 110 is in a range of 20 nm to 2 μm.

As shown in FIGS. 9 and 10, the first conductive layer 110 on the nanoimprint pattern layer 109 (shown in FIG. 8) is removed, and the first conductive layer 110 on the forming surface A is retained to constitute the first extension electrode 111 and the second extension electrode 121.

After the nanoimprint pattern layer 109 is removed, a portion of the space occupied by the nanoimprint pattern layer 109 is used to form the concave spots 130.

In this exemplary embodiment, the first conductive layer 110 on the nanoimprint pattern layer 109 is removed by a lift off process. Specifically, the first conductive layer 110 on the nanoimprint pattern layer 109 may be lifted off by a tape.