Light source, manufacturing method of light source, lighting apparatus, and display apparatus
View Patent ↗Provided is a light source that has high reliability and hardly causes conductivity failure between a light emitting device and a conductive land. In an LED light source of the present invention, an LED bare chip is mounted to conductive lands of a substrate, using bumps ( 55 a, 55 b ). The LED bare chip (D 65 ) is provided with a p-electrode (Lp) and an n-electrode (Ln) on a rear surface. The p-electrode (Lp) is larger in area than the n-electrode (Ln). The p-electrode (Lp) is bonded to a corresponding conductive land via four bumps ( 55 a ), whereas the n-electrode (Ln) is bonded to a corresponding conductive land via one bump ( 55 b ). A bonded area (Sn) between the n-electrode (Ln) and the bump ( 55 b ) is larger than a bonded area (Sp) between the p-electrode (Lp) and one of the bumps ( 55 a ).
1. A light source comprising:
at least one light emitting device, a rear surface of which is provided with two electrodes that differ from each other in area;
a substrate having conductive lands formed in correspondence with the electrodes; and
a plurality of bumps, each of which exists between a corresponding one of the electrodes and a corresponding one of the conductive lands, and has a first portion bonded to the corresponding electrode and a second portion bonded to the corresponding conductive land, wherein
the electrode being larger in area is bonded by a greater number of bumps than the electrode being smaller in area, and a bump having the smallest portion in area of all first and second portions of the plurality of bumps exists on the larger-area electrode.
2. The light source of claim 1 , wherein
there is at least one bump having the largest portion in area of either the first portions or the second portions of the plurality of bumps, the either the first portions or the second portions including the smallest portion in area of all the first and second portions, and the at least one bump exists on the smaller-area electrode.
3. The light source of claim 2 , wherein
at least one of first and second portions is substantially the same in area for all the bumps existing on the larger-area electrode.
4. The light source of claim 1 ,
only one bump exists on the smaller-area electrode.
5. The light source of claim 3 ,
only one bump exists on the smaller-area electrode.
6. The light source of claim 1 , wherein
the bumps existing on the larger-area electrode are arranged substantially in an orderly formation.
7. The light source of claim 5 , wherein
the bumps existing on the larger-area electrode are arranged substantially in an orderly formation.
8. The light source of claim 3 , wherein
all the bumps existing on the larger-area electrode are the same in area within each of the first and second portions, and the largest area of all the first and second portions of the plurality of bumps is at least 1.2 times the area of one of the bumps existing on the larger-area electrode.
9. A lighting apparatus comprising a light source of claim 1 .
10. A display apparatus comprising a light source of claim 1 .
11. A manufacturing method of a light source, in which at least one light emitting device is mounted to conductive lands of a substrate via a plurality of bumps, the light emitting device having two electrodes on a rear surface, the electrodes differing from each other in area, wherein
the electrode being larger in area is bonded by a greater number of bumps than the electrode being smaller in area, and a bump that is bonded with an electrode and a conductive land in the smallest area among the plurality of bumps is used to bond the larger-area electrode.
12. The manufacturing method of claim 11 , wherein
only one bump is used to bond the smaller-area electrode.
13. The manufacturing method of claim 11 , wherein
the largest one of the bumps is used to bond the smaller-area electrode.
14. The manufacturing method of claim 12 , wherein
the largest one of the bumps is used to bond the smaller-area electrode.
15. The manufacturing method of claim 12 , wherein
the bumps used to bond the larger-area electrode have substantially the same size.
16. The manufacturing method of claim 14 , wherein
the bumps used to bond the larger-area electrode have substantially the same size.
17. The manufacturing method of claim 12 , wherein
the bumps existing on the larger-area electrode are arranged substantially in an orderly formation.
18. The manufacturing method of claim 16 , wherein
the bumps existing on the larger-area electrode are arranged substantially in an orderly formation.
19. The manufacturing method of claim 12 , wherein
the light emitting device is mounted to the conductive lands in ultrasound bonding, and a load exercised to the light emitting device in the ultrasound bonding increases over time.
20. The manufacturing method of claim 18 , wherein
the light emitting device is mounted to the conductive lands in ultrasound bonding, and a load exercised to the light emitting device in the ultrasound bonding increases over time.