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:
a pair of light-transmissive insulator sheets each provided with a light-transmissive electroconductive layer, or a pair of a light-transmissive insulator sheet provided with light-transmissive electroconductive layers and a light-transmissive insulator sheet which is free from a light-transmissive electroconductive layer, disposed opposite to each other so as to form a region between the pair,
one or more light-emitting semiconductor element each provided with a cathode and an anode which are individually and electrically connected to respective ones of said light-transmissive electroconductive layers, and a light-transmissive elastomer, respectively disposed between the pair of light-transmissive insulator sheets so as to fill the region in combination,
wherein the light-transmissive elastomer is at least partially present in the interface between the cathode and anode of the light-emitting semiconductor element and the light-transmissive electroconductive layers,
the light-transmissive elastomer is also filled in concavities of the cathode and anode surfaces, and
the light-emitting device exhibits a flexural resistance in terms of a lighting maintenance rate of at least 3/6 at a bending radius of 20 nm or at least 5/6 at a bending radius of 30 mm when the light-emitting device in a lighting state is wound about a round bar having a specified bending radius.
2 . The light-emitting device according to claim 1 , wherein said light-transmissive elastomer covers 10-90% each of the cathode area and the anode area of said light-emitting semiconductor element.
3 . The light-emitting device according to claim 1 , wherein said light-transmissive elastomer has a Vicat softening temperature of 80-160° C.
4 . The light-emitting device according to claim 1 , wherein said light-transmissive elastomer has a melting temperature which is at least 180° C. or at least 40° C. higher than Vicat softening temperature.
5 . The light-emitting device according to claim 1 , wherein said light-transmissive elastomer has a tensile storage elastic modulus of 0.01 GPa-10 GPa in a temperature range of 0 to 100° C.
6 . The light-emitting device according to claim 1 , wherein said light-transmissive elastomer has a glass transition temperature of at most −20° C.
7 . The light-emitting device according to claim 1 , wherein said light-transmissive elastomer is not melted at the Vicat softening temperature, or has a tensile storage elastic modulus of at least 0.1 MPa at the Vicat softening temperature.
8 . The light-emitting device according to claim 1 , wherein each of the cathode and anode of the light-emitting semiconductor element has a surface roughness Ra of 0.1-10 μm.
9 . The light-emitting device according to claim 1 , wherein said light-transmissive elastomer comprises an acrylic elastomer.
10 . The light-emitting device according to claim 1 , wherein said light-transmissive elastomer is a polymeric elastic material.
11 . The light-emitting device according to claim 1 , wherein the light-transmissive electroconductive layer comprises a conductor film, a transparent resin layer containing a particulate conductor, or a mesh electrode.
12 . The light-emitting device according to claim 1 , wherein the light-transmissive electroconductive layer comprises a sputtered film or vapor-deposited film of a conductor.
13 . The light-emitting device according to claim 1 , wherein the light-transmissive electroconductive layer comprises a mesh electrode layer.
14 . The light-emitting device according to claim 1 , wherein the light-transmissive electroconductive layer comprises a plurality of light-transmissive electroconductive fillers and a light-transmissive resin binder binding the electroconductive fillers in a mutually contacting state.
15 . The light-emitting device according to claim 14 , wherein the electroconductive fillers occupy 50-95 wt. % of the light-transmissive electroconductive layer.
16 . The light-emitting device according to claim 1 , wherein at least one of the anode and the cathode of the light-emitting semiconductor element is connected to a corresponding light-transmissive electroconductive layer via a bump electrode.
17 . The light-emitting device according to claim 1 , wherein the light-transmissive electroconductive layer has a sheet resistivity of at most 1000 ohm/□.
18 . The light-emitting device according to claim 1 , wherein the light transmissive electroconductive layer has a thickness of 0.1-10 μm.
19 . The light-emitting device according to claim 1 , which is free from bubbles having an outer diameter which is equal to or larger than 500 μm or the chip size of the light-emitting semiconductor element.
20 . A process for producing a light-emitting device according to claim 1 , comprising:
disposing a light-transmissive elastomer between an electrode surface of a light-emitting semiconductor element and a surface of a light-transmissive electroconductive layer 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.
21 . An apparatus, comprising a display apparatus or an illumination apparatus including a light-emitting device according to claim 1 .