Light-emitting device with improved flexural resistance and electrical connection between layers, production method therefor, and device using light-emitting device
A light-emitting device includes a pair of light-transmissive insulator sheets disposed opposite to each other and two types of light-transmissive electroconductive layers disposed on a common one of or separately on one and the other of the pair of light-transmissive insulator sheets, and at least one light-emitting semiconductor each provided with a cathode and an anode which are individually and electrically connected to the two types of the light-transmissive electroconductive layers. The electrical connection and mechanical bonding between the members are improved by a light-transmissive elastomer which is between the pair of light-transmissive insulator sheets. A method in which a light-emitting semiconductor element and a light-transmissive electroconductive member are subjected to vacuum hot-pressing.
1. A flexible light-emitting device, comprising:
first and second light-transmissive and flexible insulator sheets;
first and second light-transmissive electroconductive layers;
a light-emitting semiconductor element comprising a first electrode electrically connected to the first light-transmissive electroconductive layer, and a second electrode electrically connected to the second light-transmissive electroconductive layer, wherein each of the first electrode and the second electrode has a surface that has convexities and concavities; and
an insulating light-transmissive elastomer disposed at least (i) in a part of a region between the first electrode and the first light-transmissive electroconductive layer, and in the concavities of the surface of the first electrode, and (ii) in a part of a region between the second electrode and the second light-transmissive electroconductive layer, and in the concavities of the surface of the second electrode; wherein:
the first and second light-transmissive electroconductive layers, the light-emitting semiconductor element, and the light-transmissive elastomer fill a region between the first insulator sheet and the second insulator sheet, and
the convexities of the first electrode directly contact the first light-transmissive electroconductive layer, and the second electrode is connected to the second light-transmissive electroconductive layer via a bump electrode.
2. The light-emitting device according to claim 1 , wherein the light-transmissive elastomer covers 10-90% of each of an area of the first electrode and an area of the second electrode.
3. The light-emitting device according to claim 1 , wherein each of the first electrode and the second electrode has a surface roughness Ra of 0.1-10 μm.
4. The light-emitting device according to claim 1 , wherein said light-transmissive elastomer comprises an acrylic elastomer.
5. The light-emitting device according to claim 1 , wherein the light-transmissive elastomer is a polymeric elastic material.
6. The light-emitting device according to claim 1 , wherein each of the first and second light-transmissive electroconductive layers comprises a conductor film, a transparent resin layer containing a particulate conductor, or a mesh electrode.
7. The light-emitting device according to claim 1 , wherein each of the first and second light-transmissive electroconductive layers comprises a sputtered film or vapor-deposited film of a conductor.
8. The light-emitting device according to claim 1 , wherein each of the first and second light-transmissive electroconductive layers comprises a mesh electrode layer.
9. The light-emitting device according to claim 1 , wherein each of the first and second light-transmissive electroconductive layers comprises a plurality of light-transmissive electroconductive fillers and a light-transmissive resin binder binding the electroconductive fillers in a mutually contacting state.
10. The light-emitting device according to claim 9 , wherein the plurality of light-transmissive electroconductive fillers occupy 50-95 wt. % of each of the first and second light-transmissive electroconductive layers.
11. The light-emitting device according to claim 1 , wherein each of the first and second light-transmissive electroconductive layers has a sheet resistivity of at most 1000 ohm/□.
12. The light-emitting device according to claim 1 , wherein each of the first and second light-transmissive electroconductive layers has a thickness in a range of 0.1-10 μm.
13. The light-emitting device according to claim 1 , wherein each of the first and second light-transmissive electroconductive layers are free from bubbles having a diameter that is equal to or larger than 500 μm or a chip size of the light-emitting semiconductor element.
14. A process for producing the light-emitting device according to claim 1 , comprising:
disposing the light-transmissive elastomer between an electrode surface of the light-emitting semiconductor element and a surface of the first and second light-transmissive electroconductive layers of a light-transmissive electroconductive member, and
then subjecting the light-emitting semiconductor element and the light-transmissive electroconductive member to vacuum hot pressing at a temperature which is in a range of from 10° C. below to 30° C. above the Vicat softening temperature of the light-transmissive elastomer.
15. An apparatus comprising a display apparatus or an illumination apparatus including the light-emitting device according to claim 1 .
16. The light-emitting device according to claim 1 , wherein the bump electrode comprises Au or Ag.
17. The light-emitting device according to claim 1 , wherein the bump electrode has been pressed to have a flattened top.
18. The light-emitting device according to claim 1 , wherein the bump electrode has a size of about 50-100 micro-meter in both diameter and height.
19. The light-emitting device according to claim 1 , wherein each of the first and second insulator sheets has a flexural modulus (measured according to ISO178 (JIS K7171:2008) in a range of 150 to 320 kgf/mm 2 .
20. The light-emitting device according to claim 1 , wherein the first light-transmissive electroconductive layer is located on a lower surface of the first insulator sheet, and the second light-transmissive electroconductive layer is located on an upper surface of the second insulator sheet.