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

Abstract

The present invention comprises: a device substrate having a plate-shaped base material, a pair of mounting electrodes formed in an element mounting region on the upper surface of the base material, and a pair of wiring electrodes extending from the respective ends of the pair of mounting electrodes to the outside of the element mounting region; a light-emitting element that is mounted in the element mounting region, has a pair of element electrodes joined to the pair of mounting electrodes, and emits ultraviolet light; a translucent sealing member made of an amorphous fluororesin and covering the pair of mounting electrodes, the pair of wiring electrodes, and the surface of the light-emitting element on the device substrate; and a coating film formed in at least a portion of a region covered by the sealing member on the upper surface of the device substrate. In at least a portion of the interface between the coating film and the sealing member, a compound of the material of the coating film and fluorine contained in the sealing member is formed.

Description

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

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

[0002] A light-emitting device equipped with 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 plate-shaped submount with electrodes on its upper surface, an ultraviolet light-emitting element joined to the electrodes of the submount, a coating resin that covers the surfaces of the electrodes and the ultraviolet light-emitting element on the submount, and a lens that covers the coating resin.

[0003] WO2019 / 087348 publication

[0004] In the ultraviolet light-emitting device disclosed in Patent Document 1, for example, if an amorphous fluororesin having non-reactive terminal functional groups that do not bond with the constituent material of the electrode is used as the coating resin or lens material for the ultraviolet light-emitting element, the adhesion of the coating resin to the electrode is weak, which may cause the lens to peel off from the submount together with the coating resin.

[0005] If this occurs, the sealing of the ultraviolet light-emitting device may become incomplete, leading to corrosion of the ultraviolet light-emitting element and potentially causing malfunctions such as reduced light output or failure to light up. In other words, the reliability of the light-emitting device will be reduced.

[0006] This invention has been made in view of the above-mentioned problems, and aims to provide a light-emitting device and a method for manufacturing a light-emitting device that can improve the reliability of the device while achieving an improvement in light output.

[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 invention further includes a coating film forming step, in which amorphous fluororesin pellets are placed on a first sealing member formed on the upper surface of a light-emitting element, and the amorphous fluororesin pellets are pressed from above to temporarily adhere the amorphous fluororesin pellets to the first sealing member; and 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 invention further includes a coating film forming step, in which a coating film is formed on at least a portion of the area on the upper surface of the device substrate that is covered by the first sealing member, and 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.

[0009] This is a perspective view of the light-emitting device according to Example 1. This is a top view of the light-emitting device according to Example 1. This is a cross-sectional view of the light-emitting device according to Example 1. This is a top view of the components of the light-emitting device according to Example 1. This is a cross-sectional view showing an example of the manufacturing process of the light-emitting device according to Example 1. This is a cross-sectional view showing an example of the manufacturing process of the light-emitting device according to Example 1. This is a cross-sectional view showing an example of the manufacturing process of the light-emitting device according to Example 1. This is a cross-sectional view showing an example of the manufacturing process of the light-emitting device according to Example 1. This is a cross-sectional view showing an example of the manufacturing process of the light-emitting device according to Example 1. This is a top view of the light-emitting device according to Modification 1 of Example 1. This is a top view of the light-emitting device according to Modification 2 of Example 1.

[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.

[0011] The configuration of the light-emitting device 100 according to Embodiment 1 will be described using Figures 1 to 3. Figure 1 is a perspective view of the light-emitting device 100. Figure 2 is a top view of the light-emitting device 100. Figure 3 is a cross-sectional view of the light-emitting device 100 shown in Figure 2, along line 3-3. In Figure 3, the vertical direction is the height direction of the light-emitting device 100, and the horizontal direction is the width direction of the light-emitting device 100.

[0012] [Overview of the Light-Emitting Device 100] The light-emitting device 100 is composed of a device substrate 11, a light-emitting element 13 and a protective element 15 provided on the device substrate 11, a coating film 17 provided on the device substrate 11 in the area excluding the area where the light-emitting element 13 and the protective element 15 are located, and a sealing member 19 that covers and seals the light-emitting element 13, the protective element 15 and the coating film 17 on the device substrate 11.

[0013] In Figure 2, the sealing member 19 is omitted to avoid complexity in the illustration, and hatching is applied to the coating film 17. Also in Figure 2, the center line CL is shown as a line segment that passes through the center of the upper surface of the device substrate 11 and bisects the width of the device substrate 11 in the left-right direction in the figure.

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

[0015] The base material 24 is a plate-like body having a rectangular top 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) with excellent heat dissipation properties and a thermal conductivity of 150 to 220 (W / mK). The base material 24 also contains alumina (Al ２ O ３ ), silicon nitride (Si ３ N ４ Ceramics with UV resistance properties such as those mentioned above may also be used.

[0016] Here, with reference to Figure 4, the electrode pattern provided on the upper surface of the substrate 24 will be described. Figure 4 is a top view of the device substrate 11 of the light-emitting device 100. A light-emitting element mounting electrode 25, a protective element mounting electrode 26, and a wiring electrode 27 are formed on the upper surface of the substrate 24. Hereafter, the light-emitting element mounting electrode 25, the protective element mounting electrode 26, and the wiring electrode 27 will be collectively referred to as the upper surface electrode pattern.

[0017] The light-emitting element mounting electrodes 25 are provided spaced apart from each other approximately in the center of the upper surface of the substrate 24, and each electrode has a rectangular upper surface shape. The light-emitting element mounting electrodes 25 consist of a first light-emitting element mounting electrode 25A that straddles the center line CL from left to right, and a second light-emitting element mounting electrode 25B that is 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 substrate 24 so that their long sides face each other. In the upper surface electrode pattern, the region connecting the outer edges 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 bonding the light-emitting element 13.

[0019] The protective element mounting electrodes 26 are provided spaced apart from each other in an area above the light-emitting element mounting electrodes 25 on the upper surface of the substrate 24, and each is a pair of electrodes with a rectangular upper surface shape. The protective element mounting electrodes 26 consist of a first protective element mounting electrode 26A and a second protective element mounting electrode 26B, which are approximately equal in size and face each other across a center line CL.

[0020] In the upper electrode pattern, the region connecting the outer edges of the first protective element mounting electrode 26A and the second protective element mounting electrode 26B is a protective element mounting region for mounting and joining the protective 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 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 on the upper surface of the substrate 24 so as to be symmetrical 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 base material 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 as the base material without any 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 lower surface (front surface) as protective layers. The conductive via 32 is made of Cu only as the base material.

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

[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 joined to the light-emitting element mounting electrode 25 of the device substrate 11. Here, the light-emitting element mounting electrode 25 is provided substantially at the center of the base material 24 in a plan view as described above. Therefore, the light-emitting element 13 is located substantially at the center of the device substrate 11 in a plan view.

[0032] The light-emitting element 13 is a light-emitting diode (Light Emitting Diode: LED) including an element substrate 35, a semiconductor structure layer 36 including a light-emitting layer, and a p electrode 37 and an n electrode 38 electrically connected to the semiconductor structure layer 36.

[0033] The element substrate 35 is a flat translucent substrate having a rectangular upper surface shape. In the light-emitting device 100 of the present embodiment, the element substrate 35 is made of a wurzite structure AlN single crystal. Note that the element substrate 35 can also be a sapphire (Al ２ O ３ ) single crystal.

[0034] The semiconductor structure layer 36 is a semiconductor crystal layer of an aluminum gallium nitride (AlGaN) crystal system formed across the lower surface of the element substrate 35. The semiconductor structure layer 36 is configured by laminating an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer (all not shown) in this order on the lower surface of the element substrate 35. Note that the exposed surface of the semiconductor structure layer 36 is protected by a protective film such as silicon oxide (SiO ２ ) and Al ２ O ３ .

[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. Each of the p-type semiconductor layer, the light-emitting layer, and the n-type semiconductor layer of the semiconductor structure layer 36 may include a superlattice layer, a quantum well layer, a barrier layer, and the like.

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

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

[0038] The ultraviolet light emitted from the light-emitting layer of the semiconductor structure layer 36 due to the energization of the p electrode 37 and the n electrode 38 of the light-emitting element 13 is emitted to the outside of the light-emitting element 13 from the upper surface and the side surface of the element substrate 35. That is, the upper 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-metal surface) on which N atoms are arranged on the surface. The lower surface of the element substrate 35 of the light-emitting element 13 is a +c plane (metal surface) on which Al atoms are arranged on the 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] That is, 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-metal surface) on which N atoms polarized to δ- are arranged, and is a crystal plane (N atom plane) in which the dangling bonds (unbonded hands) of the N atoms are exposed. The side surface of the element substrate 35 of the light-emitting element 13 is an a plane and an m plane or a higher-order crystal plane having dangling bonds of Al atoms and N atoms.

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

[0042] The protection element 15 is a Zener Diode (ZD) that bypasses the current flowing in the reverse direction when a voltage in the reverse direction is applied to the electrode of the light-emitting element 13 and prevents damage to the light-emitting element 13.

[0043] Note that as the protection element 15, a varistor that protects the light-emitting element 13 from a surge current that can instantaneously exceed the steady state while being electrically supplied from the outside to drive the light-emitting element 13 and obtains a constant voltage can also be used.

[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 region surrounded by the annular member 28 on the upper surface of the device substrate 11 while being separated from the annular member 28. The coating film 17 is composed of a first coating film 41 and a second coating film 42 formed separately from each other on the upper surface of the device substrate 11.

[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 FIG. 2, the second portion 41B of the first coating film 41 extends upward in the drawing from the upper end of the first portion 41A and covers the region above the protection element 15 on the upper surface of the base material 24 so as to straddle the center line CL from left to right.

[0047] Also, as shown in FIG. 2, the third portion 41C of the first coating film 41 extends downward in the drawing from the lower end of the first portion 41A and covers the region below the light-emitting element 13 on the upper surface of the base material 24 so as to straddle the center line CL 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 plan view of the device substrate 11 from 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. 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 surface of the 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 side 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, respectively, 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 adheres closely to (bonds to) the first sealing member 19A on the device substrate 11, sealing the light-emitting element 13 and the protective element 15. 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 the chemical formula 1 below, and the terminal functional group is a trifluoromethyl group (-CF) which has high light resistance to ultraviolet light at the emission wavelength of 265 nm of the light-emitting element 13. ３ )

[0060]

[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 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, AlF2). ３ ), or an aluminum fluoride intermediate (Al-F).

[0063] In the light-emitting device 100 of this embodiment, compounds derived from each other's constituent materials 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, the functional group is -CF ３ BVE-based amorphous fluororesins having perfluorocarbon functional groups such as those listed above 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, particularly 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-supporting 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 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, and therefore the terminal functional groups are -CF ３ It improves adhesion (chemical bonding) with amorphous fluororesins.

[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 (nonmetallic surface) where dangling bonds (unbonded hands) of δ- polarized N atoms are arranged, so that the terminal functional group is -CF ３ The adhesion (chemical bonding) to the amorphous fluororesin obtained by cyclization polymerization of BVE is improved. In addition, since there are unbonded hands of N atoms on the side surfaces (e.g., a-face, m-face) of the element substrate 35, the terminal functional groups are -CF ３ The adhesion (chemical bonding) to amorphous fluororesin obtained by cyclization polymerization of BVE is 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 terminal functional group is -CF ３The adhesion (chemical bonding) to amorphous fluororesin obtained by cyclization polymerization of BVE 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. The Al material that makes up 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 with excellent reliability 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 it is even more preferable that it 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 for 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 for 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 Substrate Preparation Process] First, as shown in Figure 5, a device substrate 11 is prepared, on which an upper electrode pattern, annular member 28, mounting electrode 31, conductive via 32, and 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 formation 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 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 22 wt% 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 the 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 20 wt% 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 step] Next, a first sealing member 19A is formed to cover the upper surface of the substrate 24, the surfaces of the upper side 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 the 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, which is a 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 process 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 serving as an auxiliary adhesive layer.

[0094] Specifically, first, the device substrate 11 is placed on a sample stand (not shown) of a 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 10 gf to 100 gf 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.

[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 rectangular prism shape with sides of 1.8 mm on the top and bottom surfaces, and 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 prism 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] [Modification 1] Next, Modification 1 of the light-emitting device 100 according to Example 1 will be described with reference to 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 the same as 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] [Modification 2] Next, Modification 1 of the light-emitting device 100 according to Example 2 will be described with reference to 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 the same as 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.

[0114] 100, 110, 120 Light-emitting device 11 Device substrate 13 Light-emitting element 15 Protective element 17 Coating film 19 Sealing member 19A First sealing member 19B Second sealing member 25 Light-emitting element mounting electrode 26 Protective element mounting electrode 27 Wiring electrode 28 Annular member 31 Mounting electrode 41 First coating film 42 Second coating film 43 Third coating film

Claims

1. A light-emitting device comprising: 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 mounted in the element mounting region and having a pair of element electrodes joined to the pair of mounting electrodes and emitting ultraviolet light; a translucent 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, 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.

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 light-emitting device according to any one of claims 1 to 3, wherein the light-emitting device has an annular member formed on the upper surface of the substrate, 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, and the coating film is formed in 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 mounting electrodes, a second coating film covering the other mounting electrode of the pair of mounting 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 light-emitting device according to claim 5, characterized in that the pair of wiring electrodes are composed of a first wiring electrode on the anode side and a second wiring electrode on the cathode side, and the coating film is composed of 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 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 forming 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; a temporary bonding step of 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 the amorphous fluororesin pellets to the first sealing member; A method for manufacturing a light-emitting device, comprising: 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 comprising 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, wherein a compound of the coating film material and fluorine contained in the first sealing member is formed at 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