Display apparatus

1. A display device comprising:

a substrate comprising a display region, and a peripheral region that is outside of the display region;

a plurality of dummy pads at the peripheral region;

an insulating layer completely covering the plurality of dummy pads such that each of the plurality of dummy pads does not contact a conductive layer, wherein top surfaces of first portions of the insulating layer above centers of the plurality of dummy pads are higher than top surfaces of second portions of the insulating layer between the plurality of dummy pads such that a first distance from a top surface of the substrate to the top surfaces of the first portions of the insulating layer is greater than a second distance from the top surface of the substrate to top surfaces of

a plurality of pads over the second portions of the insulating layer at the peripheral region.

2. The display device of claim 1 , further comprising:

conductive balls having a diameter that is greater than a difference between the first distance and the second distance, and being in electrical contact with the top surfaces of the plurality of pads; and

an electronic chip or a printed circuit board in electrical contact with the conductive balls to be electrically connected to at least one of the pads.

3. The display device of claim 1 , further comprising a thin-film transistor at the display region, the thin-film transistor comprising:

a semiconductor layer;

a gate electrode above the semiconductor layer; and

a source electrode and a drain electrode above the gate electrode,

wherein the insulating layer extends to the display region, and is between the gate electrode and the source and drain electrodes.

4. The display device of claim 3 , wherein the plurality of pads comprise a same material as the source and drain electrodes, and

wherein the plurality of dummy pads comprise a same material as the gate electrode.

5. The display device of claim 3 , further comprising a plurality of additional dummy pads below the plurality of dummy pads and comprising a same material as the semiconductor layer.

6. The display device of claim 1 , wherein the plurality of dummy pads comprise:

a plurality of first dummy pads; and

a plurality of second dummy pads above the plurality of first dummy pads.

7. The display device of claim 6 , further comprising an additional insulating layer between the plurality of first dummy pads and the plurality of second dummy pads.

8. The display device of claim 7 , further comprising:

a first thin-film transistor at the display region, the first thin-film transistor comprising:

a first semiconductor layer;

a first gate electrode above the first semiconductor layer; and

a first source electrode and a first drain electrode above the first gate electrode; and

a second thin-film transistor in the display region of the substrate, the second thin-film transistor comprising:

a second semiconductor layer;

a second gate electrode above the second semiconductor layer and over the additional insulating layer; and

a second source electrode and a second drain electrode above the second gate electrode,

wherein the additional insulating layer extends to the display region and covers the first gate electrode, and

wherein the insulating layer extends to the display region, and is between the second gate electrode and the first and second source and drain electrodes.

9. The display device of claim 8 , wherein the plurality of pads comprise a same material as the first and second source and drain electrodes,

wherein the plurality of first dummy pads comprise a same material as the first gate electrode, and

wherein the plurality of second dummy pads comprise a same material as the second gate electrode.

10. The display device of claim 8 , further comprising a plurality of additional dummy pads below the plurality of dummy pads and comprising a same material as the first and second semiconductor layers.