Light-emitting device and method for manufacturing a light-emitting device

Abstract

The present invention provides a light-emitting device and a method for manufacturing a light-emitting device that can improve the reliability of the device while achieving increased light output. [Solution] The device substrate has a flat base plate and a pair of mounting electrodes formed in an element mounting region on the upper surface of the base plate, and a pair of wiring electrodes extending from each end of the pair of mounting electrodes outside the element mounting region; a light-emitting element that is mounted in the element mounting region and has a pair of element electrodes joined to the pair of mounting electrodes and emits ultraviolet light; a translucent sealing member made of amorphous fluororesin that covers the surface of the pair of mounting electrodes, the pair of wiring electrodes, and the light-emitting element on the device substrate; and a coating film formed on at least a part of the area covered by the sealing member on the upper surface of the device substrate, wherein a compound of the material of the coating film and fluorine contained in the sealing member is formed at at least a part of the interface between the coating film and the sealing member.

Description

Technical Field

[0001] The present invention relates to a light-emitting device including a semiconductor light-emitting element and a method for manufacturing the light-emitting device.

Background Art

[0002] A light-emitting device including a light-emitting element that emits ultraviolet light has been disclosed. For example, Patent Document 1 discloses an ultraviolet light-emitting device having a flat submount provided with an electrode on an upper surface, an ultraviolet light-emitting element joined to the electrode of the submount, a coating resin that covers the surfaces of the electrode and the ultraviolet light-emitting element on the submount, and a lens that covers the coating resin.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the ultraviolet light-emitting device disclosed in Patent Document 1, for example, when an amorphous fluororesin having a non-reactive terminal functional group that does not exhibit bonding properties with the constituent material of the electrode is used as the material of the coating resin or the lens that covers the ultraviolet light-emitting element, the adhesion of the coating resin to the electrode is weak, so there is a risk that the lens will peel off from the submount together with the coating resin.

[0005] When such a situation occurs, the sealing of the ultraviolet light-emitting device becomes incomplete, and the ultraviolet light-emitting element may be corroded, causing problems such as a decrease in light output and non-lighting. That is, the reliability of the light-emitting device is reduced.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a light-emitting device and a method for manufacturing the light-emitting device that can improve the reliability of the device while achieving an improvement in light output. [Means for solving the problem]

[0007] The light-emitting device according to the present invention comprises a device substrate having a flat substrate and a pair of mounting electrodes formed in an element mounting region on the upper surface of the substrate, and a pair of wiring electrodes extending from each end of the pair of mounting electrodes outside the element mounting region; a light-emitting element having a pair of element electrodes placed on the element mounting region and joined to the pair of mounting electrodes, and emitting ultraviolet light; a light-transmitting sealing member made of amorphous fluororesin covering the surface of the pair of mounting electrodes, the pair of wiring electrodes, and the light-emitting element on the device substrate; and a coating film formed on at least a part of the area covered by the sealing member on the upper surface of the device substrate, characterized in that a compound of the material of the coating film and fluorine contained in the sealing member is formed at at least a part of the interface between the coating film and the sealing member.

[0008] Furthermore, the method for manufacturing a light-emitting device according to the present invention includes: a device substrate preparation step of preparing a device substrate having a flat substrate and a pair of mounting electrodes formed in an element mounting region on the upper surface of the substrate, and a pair of wiring electrodes extending from each end of the pair of mounting electrodes outside the element mounting region; an element bonding step of bonding a light-emitting element that is placed on the element mounting region and emits ultraviolet light to the pair of mounting electrodes; a first sealing member formation step of applying a solution of amorphous fluororesin dissolved in a solvent to the surface of the pair of mounting electrodes, the pair of wiring electrodes, and the light-emitting element on the device substrate, and volatilizing the solvent by heat treatment to form a translucent first sealing member made of amorphous fluororesin; and softening the first sealing member. The device comprises a temporary bonding step of placing amorphous fluororesin pellets on a first sealing member formed on the upper surface of a light-emitting element, and pressing the amorphous fluororesin pellets from above to temporarily bond them to the first sealing member, and a second sealing member forming step of softening and flowing the amorphous fluororesin pellets to form a translucent second sealing member that covers the first sealing member, and further comprises a coating film forming step of forming a coating film on at least a portion of the area on the upper surface of the device substrate that is covered by the first sealing member, characterized in that a compound of the coating film material and fluorine contained in the sealing member is formed at at least a portion of the interface between the coating film and the first sealing member. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of the light-emitting device according to Example 1. [Figure 2] This is a top view of the light-emitting device according to Example 1. [Figure 3] This is a cross-sectional view of the light-emitting device according to Example 1. [Figure 4] This is a top view of the components of the light-emitting device according to Example 1. [Figure 5] This is a cross-sectional view showing an example of the manufacturing process of the light-emitting device according to Example 1. [Figure 6] This is a cross-sectional view showing an example of the manufacturing process of the light-emitting device according to Example 1. [Figure 7] This is a cross-sectional view showing an example of the manufacturing process of the light-emitting device according to Example 1. [Figure 8] This is a cross-sectional view showing an example of the manufacturing process of the light-emitting device according to Example 1. [Figure 9] This is a cross-sectional view showing an example of the manufacturing process of the light-emitting device according to Example 1. [Figure 10] This is a cross-sectional view showing an example of the manufacturing process of the light-emitting device according to Example 1. [Figure 11] This is a top view of the light-emitting device according to Modification 1 of Example 1. [Figure 12] This is a top view of a light-emitting device according to a modified example 2 of Example 1. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. In the drawings, identical components are denoted by the same reference numerals, and descriptions of redundant components are omitted. [Examples]

[0011] Using FIGS. 1 to 3, the configuration of the light-emitting device 100 according to Example 1 will be described. FIG. 1 is a perspective view of the light-emitting device 100. FIG. 2 is a top view of the light-emitting device 100. FIG. 3 is a cross-sectional view taken along line 3-3 of the light-emitting device 100 shown in FIG. 2. In FIG. 3, the vertical direction in the drawing is the height direction of the light-emitting device 100, and the horizontal direction in the drawing is the width direction of the light-emitting device 100.

[0012] [Overview of the light-emitting device 100] The light-emitting device 100 includes a device substrate 11, a light-emitting element 13 and a protection element 15 provided on the device substrate 11, a coating film 17 provided in a region excluding the region where the light-emitting element 13 and the protection element 15 on the device substrate 11 are arranged, and a sealing member 19 that covers and seals the light-emitting element 13, the protection element 15 and the coating film 17 on the device substrate 11.

[0013] In FIG. 2, in order to avoid complication of the illustration, the sealing member 19 is omitted, and the coating film 17 is hatched. Also, in FIG. 2, a line segment passing through the center of the upper surface of the device substrate 11 and bisecting the width of the device substrate 11 in the horizontal direction in the drawing is shown as the center line CL.

[0014] [Device substrate 11] First, the configuration of the device substrate 11 will be described. The device substrate 11 is a double-sided wiring substrate composed of a flat base material 24 and wiring patterns provided on both main surfaces of the base material 24.

[0015] The base material 24 is a plate-like body having a rectangular upper surface shape. In the light-emitting device 100 of this embodiment, the base material 24 is made of an insulating ceramic made of aluminum nitride (AlN) having excellent heat dissipation with a thermal conductivity of 150 to 220 (W / mK). Note that a ceramic having ultraviolet resistance characteristics such as alumina (Al2O3) or silicon nitride (Si3N4) may be used for the base material 24.

[0016] Here, while referring to FIG. 4, the electrode pattern provided on the upper surface of the base material 24 will be described. FIG. 4 is a top view of the device substrate 11 of the light-emitting device 100. On the upper surface of the base material 24, a light-emitting element mounting electrode 25, a protection element mounting electrode 26, and a wiring electrode 27 are formed. Hereinafter, the light-emitting element mounting electrode 25, the protection element mounting electrode 26, and the wiring electrode 27 are collectively referred to as the upper surface side electrode pattern.

[0017] The light-emitting element mounting electrode 25 is provided on the substantially central portion of the upper surface of the base material 24 while being spaced apart from each other, and each is a pair of electrodes having a rectangular upper surface shape. The light-emitting element mounting electrode 25 is composed of a first light-emitting element mounting electrode 25A provided straddling the center line CL from left to right and a second light-emitting element mounting electrode 25B smaller than the first light-emitting element mounting electrode 25A.

[0018] The first light-emitting element mounting electrode 25A and the second light-emitting element mounting electrode 25B are provided on the upper surface of the base material 24 such that their long sides face each other. In the upper surface side electrode pattern, the region connecting the outer edges of each of the first light-emitting element mounting electrode 25A and the second light-emitting element mounting electrode 25B is a light-emitting element mounting region for mounting and joining the light-emitting element 13.

[0019] The protection element mounting electrode 26 is provided on the region above the light-emitting element mounting electrode 25 on the upper surface of the base material 24 while being spaced apart from each other, and each is a pair of electrodes having a rectangular upper surface shape. The protection element mounting electrode 26 is composed of a first protection element mounting electrode 26A and a second protection element mounting electrode 26B that are substantially equal in size to each other and face each other with the center line CL interposed therebetween.

[0020] In the upper surface side electrode pattern, the region connecting the outer edges of each of the first protection element mounting electrode 26A and the second protection element mounting electrode 26B is a protection element mounting region for mounting and joining the protection element 15.

[0021] The wiring electrode 27 is a pair of electrodes formed on the upper surface of the substrate 24 and connected to the light-emitting element mounting electrode 25 and the protective element mounting electrode 26, respectively, on the upper surface. The wiring electrode 27 consists of a first wiring electrode 27A connected to one side of the first light-emitting element mounting electrode 25A and the first protective element mounting electrode 26A, and a second wiring electrode 27B connected to one side of the second light-emitting element mounting electrode 25B and the second protective element mounting electrode 26B.

[0022] As shown in Figure 4, the first wiring electrode 27A and the second wiring electrode 27B are formed symmetrically on the upper surface of the substrate 24 with respect to the center line CL. In the upper electrode pattern, the wiring electrodes 27 function as power supply wiring that supplies power to the light-emitting element mounting electrode 25 and the protective element mounting electrode 26, respectively.

[0023] In the upper electrode pattern, the first light-emitting element mounting electrode 25A, the first protective element mounting electrode 26A, and the first wiring electrode 27A, and the second light-emitting element mounting electrode 25B, the second protective element mounting electrode 26B, and the second wiring electrode 27B are each integrally patterned and formed. The light-emitting element mounting electrode 25, the protective element mounting electrode 26, and the wiring electrode 27 are formed by laminating nickel (Ni) and gold (Au) as protective layers on the upper surface (surface) of copper (Cu) as the base material.

[0024] In addition to the upper electrode pattern described above, an annular member 28 is formed on the upper surface of the base material 24. The annular member 28 is a ring-shaped member with an annular upper surface. The annular member 28 is provided on the upper surface of the base material 24 such that, in a plan view of the device substrate 11 from above, its inner circle and outer circle are concentric. That is, the annular member 28 has a uniform band width.

[0025] The annular member 28 surrounds the upper electrode pattern while maintaining a distance from it. That is, the region on the upper surface of the substrate 24 surrounded by the annular member 28 contains the light-emitting element mounting electrode 25, the protective element mounting electrode 26, and the wiring electrode 27, respectively.

[0026] The annular member 28 is formed by laminating Ni and Au as protective layers on the upper surface of Cu, with Cu being the base material. Alternatively, the annular member 28 may consist only of Cu, the base material, without the protective layers.

[0027] Refer again to Figures 1 to 3. Mounting electrodes 31 for mounting the light-emitting device 100 onto the circuit board are formed on the lower surface of the substrate 24. The mounting electrodes 31 are a pair of electrodes formed on the lower surface of the substrate 24, spaced apart from each other, and each has a rectangular upper surface shape.

[0028] The mounted electrode 31 is electrically connected to the wiring electrode 27 via conductive vias 32 made of conductive metal that penetrate the substrate 24 in the vertical direction in Figure 2. Specifically, the mounted electrode 31 consists of a first mounted electrode 31A electrically connected to the first wiring electrode 27A via conductive vias 32, and a second mounted electrode 31B electrically connected to the second wiring electrode 27B via conductive vias 32.

[0029] In the light-emitting device 100 of this embodiment, the mounted electrode 31 has a base material of Cu, with Ni and Au laminated in that order on its underside (surface) as protective layers. The conductive via 32 is made of Cu only as the base material.

[0030] Furthermore, in addition to Cu, other metals such as aluminum (Al) and tungsten (W) can be selected as the base material for the upper electrode pattern, annular member 28, mounted electrode 31, and conductive via 32 described above. Also, a combination of titanium (Ti) and Au, or a combination of chromium (Cr) and Au, can be selected as the protective layer.

[0031] [Light-emitting element 13] Next, the configuration of the light-emitting element 13 will be described. The light-emitting element 13 is an element bonded to the light-emitting element mounting electrode 25 of the device substrate 11. Here, as described above, the light-emitting element mounting electrode 25 is located approximately in the center of the substrate 24 in a plan view. Therefore, the light-emitting element 13 is located approximately in the center of the device substrate 11 in a plan view.

[0032] The light-emitting element 13 is a light-emitting diode (LED) comprising an element substrate 35, a semiconductor structural layer 36 including a light-emitting layer, and p electrodes 37 and n electrodes 38 electrically connected to the semiconductor structural layer 36.

[0033] The element substrate 35 is a flat, translucent substrate with a rectangular top surface. In the light-emitting device 100 of this embodiment, the element substrate 35 is made of an AlN single crystal with a wurzite structure. Alternatively, the element substrate 35 may be made of a sapphire (Al2O3) single crystal.

[0034] The semiconductor structure layer 36 is a semiconductor crystal layer of aluminum gallium nitride (AlGaN) crystal system formed across the lower surface of the device substrate 35. The semiconductor structure layer 36 is constructed by stacking an n-type semiconductor layer, an emissive layer, and a p-type semiconductor layer (none of which are shown) in that order on the lower surface of the device substrate 35. The exposed surface of the semiconductor structure layer 36 is protected by a protective film of silicon dioxide (SiO2), Al2O3, etc.

[0035] When the light-emitting element 13 is energized, ultraviolet light with a peak wavelength of 265 nm is emitted from the light-emitting layer of the semiconductor structure layer 36. Note that each of the p-type semiconductor layer, light-emitting layer, and n-type semiconductor layer of the semiconductor structure layer 36 may include a superlattice layer, quantum well layer, barrier layer, etc.

[0036] The p-electrode 37 and n-electrode 38 are electrodes electrically connected to the p-type semiconductor layer and n-type semiconductor layer of the semiconductor structure layer 36, respectively. Each of the p-electrode 37 and n-electrode 38 is bonded to the first light-emitting element mounting electrode 25A and the second light-emitting element mounting electrode 25B, respectively, via a gold-tin (Au-Sn) bonding member 39. In other words, the light-emitting element 13 is flip-chip bonded to the device substrate 11.

[0037] In the light-emitting device 100, the first light-emitting element mounting electrode 25A, the first protective element mounting electrode 26A, the first wiring electrode 27A, and the first mounting electrode 31A act as anode electrodes, while the second light-emitting element mounting electrode 25B, the second protective element mounting electrode 26B, the second wiring electrode 27B, and the second mounting electrode 31B act as cathode electrodes.

[0038] When current is applied to the p electrode 37 and n electrode 38 of the light-emitting element 13, ultraviolet light emitted from the light-emitting layer of the semiconductor structural layer 36 is emitted to the outside of the light-emitting element 13 from the top and side surfaces of the element substrate 35. In other words, the top surface of the element substrate 35 is the light-emitting surface of the light-emitting element 13.

[0039] The upper surface of the element substrate 35 is a -c plane (non-metallic surface) with nitrogen (N) atoms arranged on its surface. The lower surface of the element substrate 35 of the light-emitting element 13 is a +c plane (metallic surface) with Al atoms arranged on its surface. Here, the Al atoms in the +c axis direction are polarized to δ+, and the N atoms in the -c axis direction are polarized to δ-.

[0040] In other words, the upper surface of the element substrate 35, which is the light-emitting surface of the light-emitting element 13, is a -c plane (non-metallic plane) where δ-polarized N atoms are arranged, and is a crystal plane (N atom plane) where dangling bonds (unbonded hands) of N atoms are exposed. Furthermore, the side surfaces of the element substrate 35 of the light-emitting element 13 are a plane and an m plane or higher-order crystal plane having dangling bonds of Al atoms and N atoms.

[0041] [Protection element 15] Next, the protective element 15 will be described. The protective element 15 is an element with a rectangular top surface shape that is joined to the protective element mounting electrode 26 of the device substrate 11. As shown in Figure 2, the protective element 15 extends parallel to one side of the light-emitting element 13 on the top surface of the device substrate 11, while being separated from the light-emitting element 13.

[0042] The protective element 15 is a Zener diode (ZD) that bypasses the reverse current flowing when a reverse voltage is applied to the electrodes of the light-emitting element 13, thereby preventing damage to the light-emitting element 13.

[0043] Furthermore, as the protection element 15, a varistor (variable resistor) can be used to protect the light-emitting element 13 from surge currents that may momentarily exceed the steady state while power is supplied from an external source to drive the light-emitting element 13, and to maintain a constant voltage.

[0044] [Coating film 17] Next, the coating film 17 will be described. The coating film 17 is a pair of metal films that cover the area on the upper surface of the device substrate 11 that is surrounded by the annular member 28, while being separated from the annular member 28. The coating film 17 consists of a first coating film 41 and a second coating film 42 that are formed on the upper surface of the device substrate 11, separated from each other.

[0045] The first coating film 41 is composed of a first portion 41A, a second portion 41B, and a third portion 41C. The first portion 41A of the first coating film 41 covers the surface of the first wiring electrode 27A.

[0046] As shown in Figure 2, the second portion 41B of the first coating film 41 extends upward in the figure from the upper end of the first portion 41A and covers the area above the protective element 15 on the upper surface of the substrate 24, straddling the center line CL from left to right.

[0047] Furthermore, as shown in Figure 2, the third portion 41C of the first coating film 41 extends downward from the lower end of the first portion 41A in the figure, covering the area below the light-emitting element 13 on the upper surface of the substrate 24, with the center line CL spanning from left to right.

[0048] In other words, in the light-emitting device 100 of this embodiment, the first portion 41A of the first coating film 41 covers the first wiring electrode 27A, and the second portion 41B and the third portion 41C of the first coating film 41 cover the upper surface of the substrate 24.

[0049] The second coating film 42 covers the surface of the second wiring electrode 27B. In the coating film 17, the first portion 41A of the first coating film 41 and the second wiring electrode 27B are formed to be symmetrical with respect to the center line CL.

[0050] In a top-down view of the device substrate 11, the coating film 17 covers almost the entire area of ​​the upper surface of the device substrate 11 enclosed by the annular member 28, excluding the area where the light-emitting element 13 and the protective element 15 are provided. In the light-emitting device 100 of this embodiment, the coating film 17 is made of Al.

[0051] [Sealing member 19] Next, the sealing member 19 will be described. The sealing member 19 is a transparent member that covers the area surrounded by the annular member 28 on the upper surface of the device substrate 11. The sealing member 19 seals and protects the light-emitting element 13 and the protective element 15, and also transmits the light emitted from the light-emitting element 13, guiding the emitted light to the outside of the light-emitting device 100. The sealing member 19 consists of a first sealing member 19A and a second sealing member 19B that covers the first sealing member 19A.

[0052] The first sealing member 19A is a thin, transparent member formed along the inner edge of the annular member 28 while in contact with the inner surface of the annular member 28, and covers the upper surface of the base material 24 and the surfaces of electrodes and elements provided on the base material 24.

[0053] Specifically, as shown in Figure 3, the first sealing member 19A closely adheres (bonds) to the upper surface of the substrate 24, the upper electrode pattern (light-emitting element mounting electrode 25, protective element mounting electrode 26, wiring electrode 27), and the surfaces of the light-emitting element 13 and protective element 15, following their respective shapes. The first sealing member 19A also fills the area between the upper surface of the device substrate 11 and the lower surface of the light-emitting element 13.

[0054] The second sealing member 19B is a transparent member that covers the entire first sealing member 19A and has a bullet-shaped form that is convex upwards. In other words, the second sealing member 19B has a semi-ellipsoidal shape obtained by rotating a semi-ellipse with its major axis in the vertical direction in Figure 3.

[0055] The second sealing member 19B seals the light-emitting element 13 and the protective element 15 while adhering closely to (bonding) the first sealing member 19A on the device substrate 11. Here, the first sealing member 19A functions as an auxiliary adhesive layer for providing the second sealing member 19B on the device substrate 11.

[0056] The second sealing member 19B functions as a convex lens with the major axis of the semi-ellipsoid described above as its optical axis. In a plan view of the light-emitting device 100 from above, the centers of the light-emitting element 13, the annular member 28, and the second sealing member 19B are arranged to overlap each other.

[0057] Therefore, the light emitted from the light-emitting element 13 has a directional characteristic in which it is focused along the optical axis of the second sealing member 19B and emitted to the outside. Furthermore, if the second sealing member 19B is hemispherical or semi-ellipsoidal in shape obtained by rotating a semi-ellipse with the vertical direction as the minor axis in Figure 3, the half-angle of the emitted light from the light-emitting device 100 can be widened.

[0058] The sealing member 19 is made of a thermoplastic amorphous fluororesin (thermoplastic resin) that transmits the light emitted from the light-emitting element 13. The sealing member 19 is, for example, the S-type of Cytop® manufactured by AGC Inc.

[0059] Specifically, the amorphous fluororesin used as the constituent material of the sealing member 19 is formed by cyclization polymerization of the main chain perfluoro(4-vinyloxy-1-butene) (hereinafter also referred to as BVE), as shown in Chemical Formula 1 below, and the terminal functional group is a trifluoromethyl group (-CF3) which has high light resistance to ultraviolet light at the emission wavelength of 265 nm of the light-emitting element 13.

[0060] [ka]

[0061] Furthermore, this amorphous fluororesin has a refractive index of 1.34 and a transmittance of 90% or more for ultraviolet light. The light output of the light-emitting device 100 using this amorphous fluororesin as the sealing member 19 is improved by more than 1.5 times compared to the light output of a light-emitting device sealed using, for example, a glass cap with a convex space in which the light-emitting element 13 and the protective element 15 are housed in the space.

[0062] In the light-emitting device 100 of this embodiment, a compound of Al, which is a constituent material of the coating film 17, and fluorine (F) contained in the amorphous fluororesin, which is a constituent material of the first sealing member 19A, is formed at the interface between the coating film 17 and the first sealing member 19A. Examples of such compounds include aluminum fluoride (AlF, AlF2, AlF3) or aluminum fluoride intermediates (Al-F).

[0063] In the light-emitting device 100 of this embodiment, compounds derived from the constituent materials of each are formed at the interface between the coating film 17 and the first sealing member 19A. That is, the coating film 17 and the first sealing member 19A are chemically bonded. Therefore, the upper surface of the coating film 17 (the interface with the first sealing member 19A) changes to white after the formation of the first sealing member 19A. In other words, an interfacial layer is formed.

[0064] Here, BVE-based amorphous fluororesins having perfluorocarbon functional groups such as -CF3 exhibit excellent light resistance (e.g., resistance to yellowing) and light transmittance to ultraviolet light in the wavelength range of 220 nm to 300 nm. On the other hand, they have the characteristic of poor adhesion to other substances, especially to metals with low reactivity such as Au (gold).

[0065] Therefore, for example, if the first sealing member 19A is formed on the device substrate 11 so as to cover the surface of the upper electrode pattern, the adhesion of the amorphous fluororesin to the surface metal Au of the upper electrode pattern is low. As a result, even if the second sealing member 19B is formed on top of the first sealing member 19A, the first sealing member 19A and the second sealing member 19B may peel off from the device substrate 11 together.

[0066] When this happens, the sealing of the light-emitting device 100 becomes incomplete, the light-emitting element 13 corrodes, and malfunctions such as reduced light output or failure to light up occur. In other words, the reliability of the light-emitting device is reduced.

[0067] In the light-emitting device 100 of this embodiment, as described above, a compound of Al, which is a constituent material of the coating film 17, and F, which is contained in the amorphous fluororesin that is a constituent material of the first sealing member 19A, is formed at the interface between the coating film 17 and the first sealing member 19A, thereby improving the adhesive strength of the first sealing member 19A to the device substrate 11. In other words, the coating film 17 functions as an adhesive auxiliary film that assists in the adhesion of the sealing member 19 to the device substrate 11.

[0068] Therefore, according to the light-emitting device 100 of this embodiment, the reliability of the light-emitting device can be improved because the sealing member 19 can be prevented from peeling off from the device substrate 11 by improving the adhesive strength of the first sealing member 19A to the device substrate 11.

[0069] In this embodiment, the light-emitting device 100 uses a wurtzite-structured single-crystal AlN substrate as the element substrate 35 of the light-emitting element 13, thereby improving adhesion (chemical bonding) with amorphous fluororesin having terminal functional groups of -CF3.

[0070] In detail, the light-emitting surface (top surface) of the element substrate 35 of the light-emitting element 13 is made into a -c plane (non-metallic surface) where dangling bonds (unbonded hands) of δ-polarized N atoms are arranged, thereby improving adhesion (chemical bonding) to the amorphous fluororesin formed by cyclization polymerization of BVE with terminal functional groups of -CF3. In addition, since unbonded hands of N atoms are also present on the side surfaces (e.g., a plane, m plane) of the element substrate 35, adhesion (chemical bonding) to the amorphous fluororesin formed by cyclization polymerization of BVE with terminal functional groups of -CF3 is also improved.

[0071] Furthermore, in the light-emitting device 100 of this embodiment, since the ceramic, which is an AlN polycrystalline material, also has unbonded N atoms as the substrate 24 of the device substrate 11, the adhesion (chemical bonding) to the amorphous fluororesin obtained by cyclization polymerization of BVE with terminal functional groups of -CF3 is improved.

[0072] In the light-emitting device 100 of this embodiment, as described above, the coating film 17 covers almost the entire area of ​​the upper surface of the device substrate 11 surrounded by the annular member 28, excluding the area where the light-emitting element 13 and the protective element 15 are provided. Al, which is the constituent material of this coating film 17, has high reflectivity to ultraviolet light among other metals.

[0073] Therefore, in the light-emitting device 100 of this embodiment, the coating film 17 can reflect light that is emitted from the light-emitting element 13 and directed toward the device substrate 11, for example, light that is emitted from the light-emitting element 13, propagates through the first sealing member 19A and is directed toward the downward direction in Figure 2.

[0074] The ultraviolet light reflected by the coating film 17 travels upward in Figure 2, that is, towards the second sealing member 19B. Therefore, the formation of the coating film 17 allows more light to be concentrated on the second sealing member 19B.

[0075] Therefore, the light-emitting device 100 of this embodiment can improve the output of light emitted from the light-emitting device 100. For example, in the light-emitting device 100 of this embodiment, simulation results from optical simulations and measurement results of actual values ​​show that the light output is improved by about 7% compared to a light-emitting device in which the coating film 17 is not formed.

[0076] As described above, the light-emitting device 100 of this embodiment can provide a light-emitting device that is highly reliable while achieving improved light output. It should be noted that the compound of Al, which is a constituent material of the coating film 17, and F, which is contained in the amorphous fluororesin, a constituent material of the first sealing member 19A, only needs to be formed on at least a portion of the interface between the coating film 17 and the first sealing member 19A, and does not necessarily need to be formed across the entire interface.

[0077] Furthermore, the adhesion between the surface metal Au of the upper electrode pattern and the amorphous fluororesin may be lower than the adhesion between the ceramic substrate 24 and the amorphous fluororesin. Therefore, in the light-emitting device 100, it is preferable that the coating film 17 covers at least the surface of the upper electrode pattern, and more preferably extends to the upper surface of the substrate 24.

[0078] In this embodiment, the light-emitting device 100 does not necessarily need to have a protective element 15. That is, the upper electrode pattern provided on the upper surface of the substrate 24 may consist only of the light-emitting element mounting electrode 25 and the wiring electrode 27.

[0079] Furthermore, in the light-emitting device 100 of this embodiment, the annular member 28 is not limited to an annular shape, but can be an ellipse with a center of rotational symmetry, a petal shape with arcs radiating outwards, or a polygon with four or more sides on its upper surface. In addition, to further improve the adhesion of the first sealing member 19A to the device substrate 11, the surface metal of the annular member 28 may be Al.

[0080] [Manufacturing method for light-emitting device 100] The manufacturing method of the light-emitting device 100 will be described below with reference to Figures 5 to 10. Figures 5 to 10 are cross-sectional views showing an example of the manufacturing process of the light-emitting device 100.

[0081] The light-emitting device 100 is manufactured by a procedure that includes a device substrate preparation step of preparing a device substrate 11 including a coating film 17, an element bonding step of bonding the light-emitting element 13 and the protective element 15 to the device substrate 11, a first sealing member formation step of forming a first sealing member 19A on the device substrate 11, and a second sealing member formation step of forming a second sealing member 19B on the first sealing member 19A. Here, we will mainly describe the first sealing member formation step and the second sealing member formation step.

[0082] [Device board preparation process] First, as shown in Figure 5, a device substrate 11 is prepared, on which an upper electrode pattern, an annular member 28, mounting electrodes 31, conductive vias 32, and a coating film 17 are formed on a base material 24. Note that there are as many device substrates 11 as there are light-emitting devices 100 to be manufactured at one time, but only one is shown in Figure 5.

[0083] In the manufacturing of the device substrate 11, the upper electrode pattern, the annular member 28, the mounted electrode 31, the conductive via 32, and the coating film 17 are each formed by sequentially patterning various metals on the upper and lower surfaces of the substrate 24 using a film deposition method such as sputtering, electroless plating, or electrolytic plating.

[0084] In the light-emitting device 100 of this embodiment, the size and thickness of the base material 24 of the device substrate 11 are set to 3.6 mm on each side and 0.5 mm in thickness. In addition, in the light-emitting device 100 of this embodiment, the inner diameter of the annular member 28 is set to 2.7 mm.

[0085] [Element bonding process] Next, as shown in Figure 6, the light-emitting element 13 is bonded to the upper surface of the device substrate 11. Although not shown, a protective element 15 is also mounted on the upper surface of the device substrate 11 together with the light-emitting element 13. In this embodiment of the light-emitting device 100, the dimensions and thickness of the light-emitting element 13 are 0.95 mm on the long side, 0.75 mm on the short side, and 0.11 mm in thickness.

[0086] Specifically, first, a solder paste containing 22wt% fine particles of Au-Sn, which will become a bonding member 39 after curing, is applied to the surface of the light-emitting element mounting electrode 25 of the device substrate 11 by screen printing or potting. Similarly, solder paste is also applied to the surface of the protective element mounting electrode 26.

[0087] Next, the light-emitting element 13 is placed on the light-emitting element mounting electrode 25, which has solder paste applied to it, so that the p electrode 37 and n electrode 38 overlap. Also, the protective element 15 is placed on the protective element mounting electrode 26, which has solder paste applied to it.

[0088] Subsequently, the solder paste is heated to 300°C in a reflow oven, melting and solidifying the 20wt% Au-Sn fine particles contained in the solder paste, thereby bonding the light-emitting element 13 and the protective element 15 to the device substrate 11 via the bonding member 39. Note that paste components other than Au-Sn volatilize during the reflow process.

[0089] [First sealing member formation process] Next, a first sealing member 19A is formed that covers the upper surface of the substrate 24, the upper side electrode pattern (light-emitting element mounting electrode 25, protective element mounting electrode 26, wiring electrode 27), and the respective surfaces of the light-emitting element 13 and protective element 15.

[0090] First, as shown in Figure 7, a predetermined amount of amorphous fluororesin solution AC (hereinafter referred to as resin solution AC), which is an amorphous fluororesin that will become the first sealing member 19A, is dropped onto the upper surface of the light-emitting element 13 within the region surrounded by the annular member 28 on the upper surface of the device substrate 11.

[0091] Subsequently, the device substrate 11, onto which the resin solution AC has been dropped, is placed on a hot plate, and the underside of the device substrate 11 is heated at 230°C for 60 minutes to evaporate the solvent in the resin solution AC and dry it. After drying, heating is continued for another 60 minutes, causing the dried fluororesin to soften and spread continuously, wetting and coating the surface of the light-emitting element 13 to the upper surface of the substrate 24 inside the annular member 28.

[0092] As a result of these operations, a first sealing member 19A, which is a thin film of amorphous fluororesin, is formed on the upper surface of the device substrate 11, from the surface of the light-emitting element 13 to the upper surface of the substrate inside the annular member 28 of the device substrate 11, as shown in Figure 8. At this time, a compound consisting of Al, which is a constituent material of the coating film 17, and F, which is an amorphous fluororesin constituent material of the first sealing member 19A, is formed, improving the bonding strength of the first sealing member 19A to the device substrate 11.

[0093] [Second sealing member formation process] Next, a second sealing member 19B is formed to cover the first sealing member 19A. First, a temporary bonding step is performed in which amorphous fluororesin pellets RP (hereinafter referred to as resin pellets RP), which will become the second sealing member 19B, are temporarily bonded to the upper surface of the light-emitting element 13 of the device substrate 11, with the first sealing member 19A acting as an auxiliary adhesive layer.

[0094] Specifically, first, the device substrate 11 is placed on the sample stage (not shown) of the temporary fixing device, and the lower surface of the device substrate 11 is heated to 170°C in an atmospheric environment to soften the first sealing member 19A. Then, as shown in Figure 9, the resin pellet RP is pressed against the upper surface of the first sealing member 19A with a load of 10gf to 100gf for a loading time of 1 to 30 seconds using an adsorption collet CC so that the center of the bottom surface of the resin pellet RP coincides with the center of the light-emitting element 13, thereby pressurizing and placing it.

[0095] This operation causes the resin pellet RP to adhere to the first sealing member 19A. The resin pellet RP used in the manufacture of the light-emitting device 100 in this embodiment is a square with sides of 1.8 mm on the top and bottom surfaces, and a rectangular prism shape with a height of 1.7 mm.

[0096] Subsequently, the apparatus substrate 11 to which the resin pellets RP are bonded is placed in a vacuum oven, the oven pressure is reduced to 10 kPa, and then it is heated at 250°C for 3 hours. As a result, the resin pellets RP soften and flow as shown in Figure 10, and are eventually molded into a bullet shape as shown in Figure 3 to form the second sealing member 19B.

[0097] According to this operation, the resin pellets RP adhere well to the first sealing member 19A, so that even during prolonged heating, the resin pellets RP do not fall off or shift position, and a second sealing member 19B of a predetermined shape can be formed.

[0098] Furthermore, since the first sealing member 19A of the adhesive auxiliary layer is formed on the surface of the light-emitting element 13 and on the upper surface of the substrate 24 extending to the annular member 28 of the device substrate 11, the softened and fluidized resin of the resin pellets RP can be easily wetted and spread.

[0099] Furthermore, during the process in which the resin pellets RP soften and flow to cover the first sealing member 19A, a weldable adhesive surface is formed with the first sealing member 19A. In other words, the second sealing member 19B adheres (bonds) well to the first sealing member 19A. Note that the shape of the resin pellets RP is not limited to a rectangular prism, but can also be a polygonal prism such as a hexagonal or octagonal prism, a cylinder, or a pyramidal polygonal prism or cylinder.

[0100] Finally, the device substrate 11, which consists of the same number of light-emitting devices 100 to be manufactured at one time, is divided into individual pieces using a dicer so that each piece becomes a light-emitting device 100 having a single light-emitting element 13. This completes the manufacturing of the light-emitting devices 100.

[0101] As described above, the light-emitting device 100 of this embodiment can be manufactured by a manufacturing method including the first sealing member formation step and the second sealing member formation step. Furthermore, even if the sealing member 19 is an amorphous fluororesin, good adhesion between the sealing member 19 and the surface of the light-emitting element 13 and the upper surface of the device substrate 11 is possible. In other words, a manufacturing method for a highly reliable light-emitting device can be provided.

[0102] [Example 1] Next, a modification 1 of the light-emitting device 100 according to Example 1 will be described using Figure 11. Figure 11 is a cross-sectional view of the light-emitting device 110 according to Modification 1. The light-emitting device 110 is similar to Example 1 in all other respects, except that the manner in which the coating film 17 is formed differs from that of Example 1.

[0103] In the modified light-emitting device 110, the coating film 17 is composed of a first coating film 41, a second coating film 42, and a third coating film 43, which are formed on the upper surface of the device substrate 11 at a distance from each other.

[0104] The first coating film 41 is formed at a distance from the annular member 28 and consists of a first portion 41A and a second portion 41B. The formation of the first portion 41A and the second portion 41B of the first coating film 41 and the formation of the second coating film 42 are the same as in Example 1, so a description is omitted.

[0105] The third coating film 43 of the first coating film 41 has a semicircular upper surface shape and covers the upper surface of the substrate 24 while in contact with the annular member 28 on the upper surface of the device substrate 11. As shown in Figure 11, the third coating film 43 is formed in a region below the light-emitting element 13 on the upper surface of the substrate 24 so as to be symmetrical with respect to the center line CL.

[0106] In the modified light-emitting device 110, the third coating film 43 extends to the region on the substrate 24 that was the separation portion between the coating film 17 and the annular member 28 in the light-emitting device 100 of Example 1. This increases the adhesion area of ​​the coating film 17 to the first sealing member 19A.

[0107] Furthermore, because the third coating film 43 is separated from the first coating film 41 and the second coating film 42, the coating film 17 can be adhered to the first sealing member 19A in a more balanced manner as a whole compared to the case where the third coating film 43 is connected to either the first coating film 41 or the second coating film 42.

[0108] [Differentiation 2] Next, a modification 1 of the light-emitting device 100 according to Example 2 will be described using Figure 12. Figure 12 is a cross-sectional view of the light-emitting device 120 according to Modification 2. The light-emitting device 120 is similar to Example 1 in all other respects, except that the manner in which the coating film 17 is formed differs from that of Example 1.

[0109] In the modified light-emitting device 120, the coating film 17 is composed of a first coating film 41 and a second coating film 42 formed on the upper surface of the device substrate 11 at a distance from each other. The first coating film 41 is formed at a distance from the annular member 28 and is composed of a first portion 41A and a second portion 41B. The formation manner of the first portion 41A and the second portion 41B of the first coating film 41 is the same as in Example 1, so a description is omitted.

[0110] In the modified light-emitting device 120, the second coating film 42 of the coating film 17 is formed in contact with the annular member 28 and consists of a first portion 42A and a second portion 42B. The first portion 42A of the second coating film 42 is the portion that covers the surface of the second wiring electrode 27B, similar to the first embodiment.

[0111] As shown in Figure 11, the second portion 42B of the second coating film 42 extends from the first portion 42A to the inner edge of the annular member 28 and is formed in the region below the light-emitting element 13 on the upper surface of the substrate 24. The second portion 42B covers the region below the light-emitting element 13 on the upper surface of the substrate 24, straddling the center line CL from right to left. That is, in the light-emitting device 120 of this modified example, the cathode electrode side is in contact with the annular member 28.

[0112] Thus, when forming either the first coating film 41 or the second coating film 42 so as to be in contact with the annular member 28, it is preferable to form the second coating film 42, which is on the cathode electrode side, to extend further. This increases the adhesion area of ​​the first sealing member 19A to the coating film 17, while suppressing the ionization and release of Al during use of the light-emitting device 100, for example.

[0113] Each of the light-emitting devices described in the above-mentioned embodiments and modifications can be used as a light source for various devices. For example, each of the light-emitting devices can be used as a light source for a resin curing device, a light source for a sterilization / disinfection / sterilization device, or a sensor light source for a distance measuring device. [Explanation of Symbols]

[0114] 100, 110, 120 Light-emitting devices 11. Device circuit board 13 Light-emitting element 15 Protective elements 17 Coating membrane 19 Sealing member 19A First sealing member 19B Second sealing member 25 Electrode for mounting light-emitting element 26 Electrodes for mounting protective elements 27 Wiring electrode 28 Annular member 31. Implemented electrodes 41 First coating film 42 Second coating film 43 Third coating film

Claims

1. A device substrate having a flat base plate, a pair of mounting electrodes formed in an element mounting region on the upper surface of the base plate, and a pair of wiring electrodes extending from each end of the pair of mounting electrodes outside the element mounting region, A light-emitting element that is placed on the element mounting area and has a pair of element electrodes joined to the pair of mounting electrodes and emits ultraviolet light, On the substrate of the device, a translucent sealing member made of amorphous fluororesin covers the surface of the pair of mounting electrodes, the pair of wiring electrodes, and the light-emitting element, The device substrate has a coating film formed on at least a portion of the area covered by the sealing member on the upper surface of the substrate, A light-emitting device characterized in that a compound of the material of the coating film and fluorine contained in the sealing member is formed at least a portion of the interface between the coating film and the sealing member.

2. The light-emitting device according to claim 1, characterized in that the coating film is made of aluminum.

3. The light-emitting device according to claim 2, characterized in that aluminum fluoride is formed at least a portion of the interface between the coating film and the sealing member.

4. The light-emitting device according to any one of claims 1 to 3, characterized in that the coating film is formed to cover at least each of the pair of wiring electrodes.

5. The substrate has an annular member formed on its upper surface, which is separated from the pair of mounting electrodes and the pair of wiring electrodes on the upper surface of the substrate and surrounds the pair of mounting electrodes and the pair of wiring electrodes, The light-emitting device according to any one of claims 1 to 3, characterized in that the coating film is formed within the region surrounded by the annular member on the upper surface of the device substrate.

6. The light-emitting device according to claim 5, characterized in that the coating film comprises a first coating film covering one of the pair of mounted electrodes, a second coating film covering the other mounted electrode of the pair of mounted electrodes while being separated from the first coating film, and a third coating film in contact with the annular member while being separated from the first and second coating films.

7. The pair of wiring electrodes consists of a first wiring electrode on the anode side and a second wiring electrode on the cathode side. The light-emitting device according to claim 5, characterized in that the coating film comprises a first coating film that covers the first wiring electrode and is separated from the annular member, and a second coating film that covers the second wiring electrode and is in contact with the annular member.

8. The terminal functional group of the amorphous fluororesin constituting the sealing member is -CF ３ The light-emitting device according to any one of claims 1 to 3, characterized in that it is the same as the one described above.

9. The light-emitting device according to any one of claims 1 to 3, characterized in that the sealing member comprises a thin film-like first sealing member that covers the surface of the light-emitting element and the upper surface of the device substrate, and a bullet-shaped second sealing member that covers the first sealing member and is convex upward.

10. The light-emitting device according to any one of claims 1 to 3, characterized in that the light-emitting element emits ultraviolet light with a wavelength of 200 nm to 300 nm.

11. A device substrate preparation step involves preparing a device substrate having a flat base plate, a pair of mounting electrodes formed on the upper surface of the base plate in an element mounting region, and a pair of wiring electrodes extending from each end of the pair of mounting electrodes outside the element mounting region. A component bonding step involves bonding a light-emitting element, which is placed on the component mounting area and emits ultraviolet light to the pair of mounting electrodes, A first sealing member forming step involves applying a solution of amorphous fluororesin dissolved in a solvent to the surfaces of the pair of mounting electrodes, the pair of wiring electrodes, and the light-emitting element on the substrate of the apparatus, and then volatilizing the solvent by heat treatment to form a translucent first sealing member made of amorphous fluororesin. A temporary bonding step involves softening the first sealing member, placing amorphous fluororesin pellets on the first sealing member formed on the upper surface of the light-emitting element, and pressing the amorphous fluororesin pellets from above to temporarily bond them to the first sealing member, The process includes a second sealing member forming step, in which the amorphous fluororesin pellets are softened and flowed to form a translucent second sealing member that covers the first sealing member, The process further includes a coating film forming step of forming a coating film on at least a portion of the area covered by the first sealing member on the upper surface of the device substrate, A method for manufacturing a light-emitting device, characterized in that a compound of the material of the coating film and fluorine contained in the first sealing member is formed at least a portion of the interface between the coating film and the first sealing member.

12. The method for manufacturing a light-emitting device according to claim 11, characterized in that the coating film is made of aluminum.

Images