Display device having improved reliability of pad portion

A display device comprising:

• a substrate including a display area and a non-display area;
• a transistor and a light emitting element which are disposed on the display area;
• a pad portion disposed in the non-display area, wherein the pad portion includes a metal pattern;
• and
• a printed circuit board or a data driver, which is connected with the pad portion,
• wherein the transistor comprises:
• a semiconductor layer disposed on the substrate;
• and
• a source electrode or a drain electrode which is electrically connected with the semiconductor layer,
• wherein the source electrode or the drain electrode comprises:
• a first layer including a first metal;
• a second layer including a second metal;
• and
• a third layer including the first metal,
• wherein the metal pattern includes the first metal, and is connected with the printed circuit board or the data driver, and
• wherein the metal pattern consists of:
• a first sub-metal pattern including the first metal;
• and
• a second sub-metal pattern including the second metal,
• wherein a thickness of the second sub-metal pattern is thinner than a thickness of the second layer.