Flat bonding method of light emitting device and flat bonder for light emitting device
A flat bonding method of light emitting devices including bonding light emitting devices on a circuit board using a reflow process, and re-bonding at least a portion of the light emitting devices bonded on the circuit board using a press plate while pressing the portion of the light emitting devices.
1. A display panel, comprising:
a circuit board facing a first direction and including pads;
light emitting devices mounted on the circuit board and including a substrate; and
metal bonding layers bonding the pads to the light emitting devices,
wherein:
the substrate is disposed on an opposite side of the circuit board and is configured to transmit light generated by the light emitting device;
an angular difference between a planar direction of an upper surface of the light emitting device and the first direction is less than 5 degrees in one of the light emitting devices; and
opposing distal ends of the upper surface of the light emitting device are disposed at different elevations.
2. The display panel of claim 1 , wherein the angular difference is less than 5 degrees in at least 95% of the light emitting devices.
3. The display panel of claim 1 , wherein a difference between an elevation of the highest upper surface and that of a next highest upper surface among the upper surfaces of the light emitting devices is less than 1 μm.
4. The display panel of claim 1 , wherein a deviation in elevations of upper surfaces of the light emitting devices is in a range of about 2 μm in at least 50% of the light emitting devices.
5. The display panel of claim 4 , wherein the deviation is in a range of about 2 μm in at least 90% of the light emitting devices.
6. The display panel of claim 1 , wherein the metal bonding layers protrude outside of the ends of the light emitting devices.
7. The display panel of claim 1 , wherein at least one of the light emitting devices has a size of 80 μm×120 μm.
8. The display panel of claim 1 , wherein an interval between adjacent light emitting devices is greater than a width of one of the light emitting devices.
9. The display panel of claim 1 , wherein upper surfaces of the light emitting devices have substantially same planar directions.
10. The display panel of claim 1 , wherein the amount of material forming the metal bonding layer between the light emitting devices are different from each other.
11. The display panel of claim 1 , wherein a width of the metal bonding layer is greater than a width of the pad along a second direction perpendicular to the first direction.