Method and apparatus for testing light-emitting device
Disclosed is a method for testing a light-emitting device comprising the steps of: providing a light-emitting device comprising a plurality of light-emitting diodes; driving the plurality of the light-emitting diodes with a current; generating an image of the light-emitting device; and determining a luminous intensity of each of the light-emitting diodes; wherein the magnitude of the current is determined such that the current density driving each of the light-emitting diodes is smaller than or equal to 300 mA/mm 2 .
1. A method for testing a light-emitting device comprising the steps of:
providing a light-emitting device comprising a plurality of light-emitting diodes;
driving the plurality of the light-emitting diodes with a current;
generating an image of the light-emitting device; and
determining a luminous intensity of each of the light-emitting diodes;
wherein the magnitude of the current is determined such that the current density driving each of the light-emitting diodes is smaller than or equal to 300 mA/mm 2 .
2. The method as claimed in claim 1 , wherein the magnitude of the current is a substantially constant value.
3. The method as claimed in claim 1 , wherein the light-emitting device comprises only two pads for the current to be provided.
4. The method as claimed in claim 1 , wherein the luminous intensity is determined according to a gray level of the image.
5. The method as claimed in claim 1 , wherein the step of generating the image of the light-emitting device comprises providing an image receiving device and receiving the image of the light-emitting device from the image receiving device.
6. The method as claimed in claim 5 , wherein the image receiving device is a microscope.
7. The method as claimed in claim 5 , wherein the image receiving device further comprises an image sensor to capture the image of the light-emitting device.
8. The method as claimed in claim 5 , wherein the image receiving device further comprises a filter for filtering off a specific range of the wave length of light.
9. The method as claimed in claim 1 , wherein the step of determining the luminous intensity of each of the light-emitting diodes with the image is performed manually by a human being with eyes.
10. The method as claimed in claim 1 , wherein the step of determining the luminous intensity of each of the light-emitting diodes with the image is performed automatically by an automated equipment.
11. The method as claimed in claim 1 , further comprising generating an intensity map showing the position of each of the light-emitting diodes and its corresponding luminous intensity.
12. The method as claimed in claim 1 , further comprising comparing the luminous intensity of each of the light-emitting diodes with a pre-determined luminous intensity for determining whether each of the light-emitting diodes is a defective light-emitting diode or not.
13. The method as claimed in claim 12 , further comprising comparing the number of defective light-emitting diodes with a pre-determined number.
14. The method as claimed in claim 1 , wherein the light-emitting device is tested in a wafer form.
15. The method as claimed in claim 14 , further comprising generating an qualification status map showing the position of tested light-emitting device and its qualification status in the wafer, wherein the qualification status comprises a qualified status or an unqualified status.
16. The method as claimed in claim 15 , further comprising marking the unqualified light-emitting device.
17. The method as claimed in claim 1 , wherein the plurality of light-emitting diodes is monolithically formed as a chip.
18. The method as claimed in claim 1 , wherein the plurality of light-emitting diodes is connected in series.