Display device and inspection method of bonding resistance

A display device comprising:

• a display panel comprising a first substrate including a display area and a peripheral area disposed outside the display area;
• a first circuit board including a second substrate bonded to the display panel;
• and
• a second circuit board including a third substrate bonded to the first circuit board,
• wherein the display panel comprises
• a plurality of pixels disposed in the display area,
• a plurality of data lines connected to the plurality of pixels,
• an inspection circuit unit disposed in the peripheral area and connected to the data lines,
• a driving circuit unit disposed in the peripheral area,
• a first wire and a second wire connected to the driving circuit unit, and
• a third wire connected to the inspection circuit unit,
• the first circuit board and the second circuit board comprise a bonding region comprising a plurality of pads,
• the inspection circuit unit comprises a first switching element and a second switching element,
• the first switching element is electrically connected to a first data line among the plurality of data lines and to the third wire,
• the second switching element is electrically connected to a second data line among the plurality of data lines and to the second wire,
• the plurality of pads comprises a first pad, a second pad, a third pad, and a fourth pad, the first pad and the second pad being electrically connected to each other via a first conductor, and the third pad and the fourth pad being electrically connected to each other via a second conductor,
• the second pad and the fourth pad are disposed at the second circuit board and are electrically connected to each other, and
• the first pad is electrically connected to the third wire, and the third pad is electrically connected to the first wire.

A display device comprising:

• a plurality of pixels;
• a plurality of data lines connected to the plurality of pixels;
• an inspection circuit unit connected to the plurality of data lines;
• a driving circuit unit connected or configured to be connectable to the plurality of data lines;
• a bonding region comprising a first pad, a second pad, a third pad, and a fourth pad, the first pad and the second pad being electrically connected to each other through a first conductor, and the third pad and the fourth pad being electrically connected to each other through a second conductor;
• a first wire connected to the driving circuit unit and the third pad;
• a second wire connected to the driving circuit unit and the inspection circuit unit;
• and
• a third wire connected to the inspection circuit unit and the first pad,
• wherein the second pad and the fourth pad are electrically connected to each other.

An inspection method of a bonding resistance, in a display device comprising a plurality of pixels, a plurality of data lines connected to the plurality of pixels, an inspection circuit unit connected to the plurality of data lines, a driving circuit unit connected or configured to be connectable to the plurality of data lines, a bonding region comprising a first pad and a second pad electrically connected to each other through a first conductor, and a third pad and a fourth pad electrically connected to each other through a second conductor, a first wire connected to the driving circuit unit and the third pad, a second wire connected to the driving circuit unit and the inspection circuit unit, and a third wire connected to the inspection circuit unit and the first pad, wherein the second pad and the fourth pad are electrically connected to each other, the method comprising:

• applying, by the driving circuit unit, a first inspection data voltage of a first gray level to the first wire and the second wire;
• applying, by the driving circuit unit, a second inspection data voltage of a second gray level to the first wire and the second wire;
• and
• inspecting a lighting state of the plurality of pixels and determining whether a bonding resistance of the bonding region is normal.