Light emitting device and method for manufacturing the same

Abstract

To provide a method for manufacturing a light emitting device with high optical output and excellent reliability.SOLUTION: A manufacturing method includes the steps of applying a solution of fluororesin dissolved in a solvent to become amorphous fluororesin to the upper surface of a device substrate and the surface of a light-emitting element, and then volatilizing the solvent to form a first sealing member that is a thin film of amorphous fluororesin, a temporary fixing step of pressing and adhering amorphous fluororesin pellets to the softened first sealing member on the upper surface of the light-emitting element, and a step of softening and flowing the amorphous fluororesin pellets to form a second sealing member bonded to the first sealing member.SELECTED DRAWING: Figure 12

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 same. [Background technology]

[0002] Patent Document 1 discloses an ultraviolet light emitting device and a manufacturing method thereof, which comprises injecting a coating liquid containing dissolved amorphous fluororesin into a recess in a submount, heating and drying the coating to form a resin film that covers the inner wall surfaces of the side and bottom of the submount and the top and side surfaces of an ultraviolet light emitting element flip-chip mounted on the bottom of the submount, and then pouring solid amorphous fluororesin into the recess space of the submount covered with the resin film and heating and melting the resin film to form a resin film that fills the recess.The ultraviolet light device has a structure in which a condenser lens is fixed with an adhesive to the top surface of the resin film that fills the recess. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2014 / 178288 publication Summary of the Invention [Problem to be solved by the invention]

[0004] In the ultraviolet light-emitting device described above, when an amorphous fluororesin having a non-reactive terminal functional group that does not bond to metals, etc. is used, there is a problem that the resin film on the upper surface or side surface of the ultraviolet light-emitting element peels off, reducing the light output of the ultraviolet light-emitting device. In addition, the manufacturing process of the ultraviolet light-emitting device described above includes a step of filling the recessed space of the submount having sidewalls with amorphous fluororesin, which complicates the structure and manufacturing method of the ultraviolet light-emitting device.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an ultraviolet light emitting device having high light output and excellent reliability, or a method for manufacturing an ultraviolet light emitting device. [Means for solving the problem]

[0006] In order to achieve the above object, a method for manufacturing a light emitting device includes a device substrate having a flat base material, a plurality of bonding lands, and a circular member that surrounds the plurality of bonding lands at a distance from each other; a light emitting element that emits ultraviolet light and is flip-connected to the plurality of bonding lands of the device substrate; and a sealing member made of amorphous fluororesin that transmits light emitted from the light emitting element and covers an upper surface of the light emitting element and the device substrate, The manufacturing method includes: a step of applying a solution of a fluororesin that becomes an amorphous fluororesin to an upper surface of the device substrate and a surface of the light emitting element, and volatilizing the solvent to form a first sealing member that is an amorphous fluororesin in a thin film form; a temporary fixing step of pressing and adhering an amorphous fluororesin pellet to the softened first sealing member on the upper surface of the light emitting element; softening and fluidizing the amorphous fluororesin pellets to form a second sealing member bonded to the first sealing member; The present invention is characterized by comprising:

[0007] The light emitting device includes: a device substrate having a flat base material, a plurality of bonding lands, and a circular member that surrounds the plurality of bonding lands at a distance; a light emitting element that emits ultraviolet light and is flip-connected to the plurality of bonding lands of the device substrate; a sealing member made of amorphous fluororesin that transmits light emitted from the light-emitting element and covers the light-emitting element and an upper surface of the device substrate, the substrate is an AlN ceramic substrate having ultraviolet light resistance; The light emitting element has a surface in contact with the amorphous fluororesin, and the surface is a δ - is the N atomic plane polarized to The sealing member includes a first sealing member made of a thin film of amorphous fluororesin that tightly covers the surface of the light-emitting element and the upper surface of the device substrate, and a second sealing member made of a convex amorphous fluororesin that tightly covers the first sealing member, The semiconductor light emitting device is characterized by comprising: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an ultraviolet light emitting device with high optical output and excellent reliability, or a method for manufacturing an ultraviolet light emitting device. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic top view of a light emitting device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of the light emitting device taken along line AA in FIG. [Figure 3] 1 is a molecular formula showing a perfluororesin sealing material in the light emitting device of this embodiment. [Figure 4] 1 is a molecular formula showing a perfluororesin sealing material in the light emitting device of this embodiment. [Figure 5] 10 is a molecular formula showing another perfluoro-based fluororesin used as a sealing material in the light emitting device of this embodiment. [Figure 6] FIG. 2 is a schematic cross-sectional view of a device substrate in the light emitting device of the present embodiment. [Figure 7] 3A to 3C are schematic cross-sectional views illustrating some steps of a method for manufacturing a light emitting device according to an embodiment of the present invention. [Figure 8] 3A to 3C are schematic cross-sectional views illustrating some steps of a method for manufacturing a light emitting device according to an embodiment of the present invention. [Figure 9] 3A to 3C are schematic cross-sectional views illustrating some steps of a method for manufacturing a light emitting device according to an embodiment of the present invention. [Figure 10] 3A to 3C are schematic cross-sectional views illustrating some steps of a method for manufacturing a light emitting device according to an embodiment of the present invention. [Figure 11] 3A to 3C are schematic cross-sectional views illustrating some steps of a method for manufacturing a light emitting device according to an embodiment of the present invention. [Figure 12] 3A to 3C are schematic cross-sectional views illustrating some steps of a method for manufacturing a light emitting device according to an embodiment of the present invention. [Figure 13] 3A to 3C are schematic cross-sectional views illustrating some steps of a method for manufacturing a light emitting device according to an embodiment of the present invention. [Figure 14] 3A to 3C are schematic cross-sectional views illustrating some steps of a method for manufacturing a light emitting device according to an embodiment of the present invention. [Figure 15] 10 is a table illustrating the results of a demonstration test of a resin pellet heat bonding step in a light emitting device manufacturing method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes examples of a light-emitting device and a manufacturing method thereof according to the present invention. In the following description and accompanying drawings, substantially the same or equivalent parts are designated by the same reference numerals, and descriptions of overlapping components are omitted. Furthermore, the figures do not necessarily depict the dimensional proportions of the elements in strict detail.

[0011] Fig. 1 shows a schematic top view of a light emitting device 10 of the embodiment. Fig. 2 shows a schematic cross section of the light emitting device 10 taken along line AA in Fig. 1. In the following description, the surface facing upward in Fig. 2 will be referred to as the upper surface, and the surface facing downward will be referred to as the lower surface.

[0012] As shown in Figures 1 and 2, the light emitting device 10 includes a device substrate 11 that is rectangular in plan view, a rectangular light emitting element 15 placed on the upper surface of the device substrate 11, and an amorphous fluororesin sealing member 13 that covers the upper surface of the device substrate 11 and the light emitting element 15.

[0013] The sealing member 13 includes a first sealing member 13A that covers the upper surface of the device substrate 11 and the surface of the light-emitting element 15, and a convex second sealing member 13B that covers the first sealing member 13A. The light-emitting element 15 used in the example is a semiconductor light-emitting element that emits ultraviolet light, and the sealing member 13 is a thermoplastic amorphous fluororesin that transmits the ultraviolet light emitted by the light-emitting element 15. In other words, the light-emitting device 10 is a semiconductor light-emitting device that emits ultraviolet light.

[0014] (Device board) The device substrate 11 is a double-sided wiring board in which wiring patterns for supplying power to the light emitting elements 15 are provided on both sides of an insulating base material in the form of a rectangular flat plate with an upper surface. The base material of the device substrate 11 is made of aluminum nitride (AlN) ceramic with excellent heat dissipation properties and a thermal conductivity of 150 to 220 (W / mK). The base material of the device substrate 11 can be made of ceramics with ultraviolet resistance, such as alumina (Al2O3) or silicon nitride (Si3N4).

[0015] The upper surface of the device substrate 11 is provided with a first bonding land 14A and a second bonding land 14B for bonding the light emitting element 15. The first bonding land 14A and the second bonding land 14B each have substantially the same planar shape as the first element electrode 15A and the second element electrode 15B of the corresponding light emitting element 15. Furthermore, the lower surface (back surface) of the device substrate 11 is provided with a first mounting electrode 17A and a second mounting electrode 17B for mounting the light emitting device 10 on a circuit board. The first bonding land 14A and the first mounting electrode 17A are electrically connected by a first metal via 18A that vertically penetrates the device substrate 11. Furthermore, the second bonding land 14B and the second mounting electrode 17B are electrically connected by a metal via 18B that vertically penetrates the device substrate 11.

[0016] Hereinafter, when the first bonding land 14A and the second bonding land 14B are not distinguished from each other, they will be referred to as bonding lands (14A, 14B). When the first element electrode 15A and the second element electrode 15B are not distinguished from each other, they will be referred to as element electrodes (15A, 15B). When the first mounting electrode 17A and the second mounting electrode 17B are not distinguished from each other, they will be referred to as mounting electrodes (17A, 17B). When the first metal via 18A and the second metal via 18B are not distinguished from each other, they will be referred to as metal vias (18A, 18B).

[0017] The bonding lands (14A, 14B) have a copper (Cu) base material, and a protective layer made of nickel (Ni) and gold (Au) laminated in this order is provided on their upper surface (surface). The mounting electrodes (17A, 17B) have a Cu base material, and a protective layer made of Ni and Au laminated in this order is provided on their lower surface (surface). The metal vias (18A, 18B) have a Cu base material only. Note that the protective layer provided on the surface of the base material may hereinafter be referred to as Ni / Au.

[0018] Metals such as aluminum (Al) and tungsten (W) can be selected for the base materials of the bonding lands (14A, 14B), mounting electrodes (17A, 17B), and metal vias (18A, 18B).Metals such as titanium (Ti) / gold (Au) and chromium (Cr) / gold (Au) can also be selected for the protective layer.

[0019] A circular ring member 12 having a ring shape is provided on the upper surface of the device substrate 11, surrounding the bonding lands (14A, 14B) at a distance. The circular ring member 12 is a ring having a band width in top view, and its inner and outer circles are arranged concentrically. In other words, the circular ring member 12 is a ring having a uniform band width. The inner circle of the circular ring member 12 is larger than the outer shape of the light emitting element 15 and smaller than the inscribed circle of the device substrate 11. The base material of the circular ring member 12 is Cu, and a Ni / Au protective layer is provided on its upper surface (surface). Note that the circular ring member 12 may be only a base material, and may not have a protective layer. The circular ring member 12 may also be connected to either the first mounting electrode 17A or the second mounting electrode 17B via a metal via.

[0020] The shape of the ring member 12 can be an ellipse having a center of rotational symmetry, a petal shape with radially connected arcs, or a polygon with more sides than a square. The ring member 12 only needs to have an inner surface that defines the outer edge of the first sealing member 13A, and for example, the outer surface can be the same as the outer shape of the device substrate 11.

[0021] Metals such as Al and W can be selected for the base material of the ring member 12. Metal layers such as Ti / Au and Cr / Au can also be selected for the protective layer. The ring member 12 can also be made of ceramic, the same as the base material of the device substrate 11. Silica-based inorganic cement with alumina particles or zirconia particles as aggregate can also be used.

[0022] (light-emitting element) The light-emitting element 15 includes a light-emitting functional layer LEL, which is formed by stacking an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer in this order on one surface of an element substrate SUB that is rectangular and flat in plan view. The light-emitting functional layer LEL is a semiconductor light-emitting element (LED: light-emitting diode) having a first element electrode 15A and a second element electrode 15B on the surface of the light-emitting functional layer LEL opposite the element substrate SUB. The first element electrode 15A is electrically connected to the p-type semiconductor layer, and the second element electrode 15B is electrically connected to the n-type semiconductor layer. When energized, light is emitted from the surface of the element substrate SUB. In other words, the surface of the element substrate SUB on which the light-emitting functional layer LEL is not provided is the light-emitting surface of the light-emitting element 15. The element substrate SUB of the light-emitting element 15 of this embodiment is made of aluminum nitride (AlN) single crystal, and the light-emitting functional layer LEL is an aluminum gallium nitride (AlGaN) crystal-based semiconductor crystal layer that emits light with a wavelength of 265 nm.

[0023] The element substrate SUB is an AlN single crystal with a wurtzite structure. The surface of the element substrate SUB on which the light-emitting functional layer LEL is provided is a +c-plane (metal surface) on which aluminum (Al) atoms are arranged. On the other hand, the surface of the element substrate SUB opposite to the light-emitting functional layer LEL is a -c-plane (non-metal surface) on which nitrogen (N) atoms are arranged. The Al atoms in the +c-axis direction are aligned along the δ + The N atoms in the -c axis direction are polarized to δ - That is, the light emitting surface of the light emitting element 15 is polarized in the direction of δ -The -c plane (non-metallic plane) is a crystal plane (N atom plane) on which dangling bonds of N atoms are exposed. The side surfaces of the light emitting element 15 (particularly the element substrate SUB) are a-planes and m-planes or higher-order crystal planes having dangling bonds of Al atoms and N atoms.

[0024] The AlGaN-based semiconductor crystal layer serving as the light-emitting functional layer LEL can be adjusted to emit ultraviolet light with an emission wavelength of 200 nm to 300 nm. Each of the p-type semiconductor layer, light-emitting layer, and n-type semiconductor layer of the light-emitting functional layer LEL may include a superlattice layer, a quantum well layer, a barrier layer, etc. Furthermore, each layer does not necessarily need to be doped with impurities.

[0025] The first element electrode 15A and the second element electrode 15B of the light emitting element 15 are bonded to the first bonding land 14A and the second bonding land 14B of the device substrate 11, respectively, via an Au—Sn-based bonding member 15C. In other words, the light emitting element 15 is flip-chip bonded to the device substrate 11 without wire connection. The light emitting element 15 of the embodiment is mounted so that the center of the light emitting element 15 (the intersection of the diagonals on the upper surface of the light emitting element 15) and the center of the annular member 12 coincide with each other.

[0026] (Sealing member) The sealing member 13 is a member that seals and protects the light emitting element 15, and at the same time transmits light emitted from the light emitting element 15 and guides it to the outside of the light emitting device 10. The sealing member 13 includes a thin-film first sealing member 13A that covers the upper surface of the device substrate 11 and the surfaces of the light emitting element 15 (the side surfaces, upper surface, and lower surface excluding the element electrodes (15A, 15B)), and a convex second sealing member 13B that covers the first sealing member 13A.

[0027] As shown in FIG. 2 , the first sealing member 13A adheres to and covers the upper surface (surface) of the substrate of the device substrate 11 located inside the inner surface of the annular member 12, the side surface (surface) of the bonded structure including the bonding lands (14A, 14B) of the device substrate 11, the element electrodes (15A, 15B) of the light-emitting element 15, and the bonding member 15C, as well as the lower, side, and upper surfaces (surfaces) of the light-emitting element 15 excluding the element electrodes (15A, 15B). This first sealing member 13A functions as an auxiliary adhesive layer for adhering the second sealing member 13B. The first sealing member 13A may fill the area surrounded by the upper surface of the device substrate 11, the side surface of the bonded structure, and the lower surface of the light-emitting element 15. The thickness of the first sealing member 13A may be non-uniform. For example, the thickness may be thicker at the corners of the side surface of the light-emitting element 15 and the device substrate 11. Such a first sealing member 13A can be formed by a solvent drying method (first sealing step) described below.

[0028] The second sealing member 13B is provided in a convex shape and tightly adheres (bonds) to the upper surface of the first sealing member 13A, which serves as an auxiliary adhesive layer, to cover the latter. In the embodiment, the second sealing member 13B is a spheroid formed by rotating a semi-ellipse with its major axis in the vertical direction. The second sealing member 13B is also circular, defined by the inner surface of the annular member 12 on the upper surface of the device substrate 11. That is, the second sealing member 13B is a convex lens, and the major axis of the spheroid of the second sealing member 13B is the optical axis of the convex lens. In the embodiment, the light-emitting element 15 is positioned so that its center overlaps the center of the annular member 12. Therefore, the light emitted from the light-emitting element 15 has a directional characteristic of focusing along the lens optical axis. The half-value angle can be widened by forming the second sealing member 13B into a hemispherical shape and a semi-elliptical spheroid with its minor axis in the vertical direction. This second sealing member 13B can be formed by the pellet softening and flow method (second sealing process) described later.

[0029] The first sealing member 13A and the second sealing member 13B are made of a thermoplastic amorphous fluororesin (thermoplastic resin) that transmits the light emitted from the light-emitting element 15. In this embodiment, as shown in FIG. 3, a fluororesin whose main chain is formed by cyclopolymerization of perfluoro(4-vinyloxy-1-butene) (hereinafter also referred to as BVE) is used. The terminal functional group is a trifluoromethyl group (-CF3), which has high light resistance to the 265 nm emission wavelength of the light-emitting element 15. The refractive index of this fluororesin is 1.34, and the transmittance is 90% or more (thickness 200 μm). The light output of a light-emitting device 10 using this amorphous fluororesin as the sealing member 13 is increased by 1.5 times or more compared to the light output of a light-emitting device sealed with a glass cap.

[0030] Similar fluororesin main chains include perfluoro(allyl vinyl ether) cyclized polymers as shown in Figure 4 and copolymers of perfluoro(2,2-dimethyl-1,3-dioxole) and tetrafluoroethylene as shown in Figure 5. Terminal functional groups include -COOH, -CONH~Si(OR)n (R: alkyl group, n is an integer). These terminal functional groups improve adhesion to other substances. However, they have low light resistance to ultraviolet light with wavelengths of 200 nm to 300 nm.

[0031] Amorphous fluororesin having a terminal functional group of -CF3 has excellent light resistance to 265 nm ultraviolet light, but has the characteristic of extremely low adhesiveness (chemical bonding strength) with other substances. Therefore, in the light emitting device 10 of the embodiment, a single-crystal AlN substrate with a wurtzite structure is used for the element substrate SUB of the light emitting element 15, and a ceramic AlN polycrystalline body is used for the base material of the device substrate 11, thereby improving adhesiveness (chemical bonding strength) with the amorphous fluororesin having a terminal functional group of -CF3.

[0032] In detail, the light emitting surface (upper surface) of the element substrate SUB of the light emitting element 15 is set to δ -By forming the -c plane (non-metallic surface) on which dangling bonds of polarized N atoms are arranged, adhesiveness (chemical bonding) with the amorphous fluororesin obtained by cyclopolymerization of BVE with a terminal functional group of -CF3 is improved. Furthermore, since dangling bonds of N atoms are also present on the side surfaces (e.g., a-plane and m-plane) of the element substrate SUB, adhesiveness (chemical bonding) with the amorphous fluororesin obtained by cyclopolymerization of BVE with a terminal functional group of -CF3 is improved. Similarly, since dangling bonds of N atoms are also present on the ceramic, which is a polycrystalline sintered body of AlN that is the base material of the device substrate 11, adhesiveness (chemical bonding) with the amorphous fluororesin obtained by cyclopolymerization of BVE with a terminal functional group of -CF3 is improved. Additionally, the surface of the ceramic, which is a polycrystalline sintered body of AlN that is the base material of the device substrate 11, has fine irregularities, which improve adhesiveness (physical bonding). Therefore, even if the first sealing member 13A is an amorphous fluororesin having a terminal functional group of -CF3, the adhesiveness between the light emitting element 15 and the base material of the device substrate 11 can be improved.

[0033] In the present embodiment, the second sealing member 13B is made of the same amorphous fluororesin as the first sealing member 13A. Therefore, the adhesion between the first sealing member 13A and the second sealing member 13B is excellent. Therefore, the light-emitting device 10 can be configured with a convex lens-shaped sealing member 13 provided on the upper surface of the flat device substrate 11. In other words, the device substrate 11 does not require a recess (frame) for holding the sealing member 13 (especially the second sealing member 13B), simplifying the structure of the light-emitting device 10. Furthermore, the absence of a recess (frame) in the device substrate 11 improves the light output of the light-emitting device 10. Furthermore, the sealing member 13 has an amorphous fluororesin terminal functional group formed of —CF3, which provides excellent light resistance (e.g., yellowing resistance) to ultraviolet light with a wavelength of 200 nm to 300 nm (emitted light from the light-emitting element 15). In other words, the present invention provides an ultraviolet light-emitting device with high light output and excellent reliability.

[0034] Although the above describes the embodiments, the present invention is not limited thereto. For example, a fine uneven structure can be provided on the surface of light-emitting element 15 to improve adhesion to first sealing member 13A. Furthermore, for example, two, three, four, or more light-emitting elements 15 can be arranged symmetrically about the center of the annular member to improve the light output of light-emitting device 10.

[0035] (Manufacturing method) Next, a method for manufacturing light emitting device 10 will be described. Figures 6 to 14 are diagrams schematically showing each stage of the manufacturing method. Figure 15 is a determination table for when second sealing member 13B is adhered to the upper surface of first sealing member 13A.

[0036] The light emitting device 10 is manufactured by a procedure including an element bonding process for bonding the light emitting element 15 to the device substrate 11, a first sealing process for forming a first sealing member 13A on the device substrate 11 to which the light emitting element 15 is bonded, a temporary fixing process for temporarily fixing amorphous fluororesin pellets that will become the second sealing member 13B, and a second sealing process for forming the second sealing member 13B on the device substrate 11 on which the first sealing member 13A has been formed.

[0037] First, a square device substrate 11 is prepared, which has a first bonding land 14A, a second bonding land 14B, and a circular ring member 12 with an inner diameter of 2.7 mm on the upper surface (first surface) of an AlN ceramic base material with a side length of 3.6 mm and a thickness of 0.5 mm (FIG. 6). The shapes of the first bonding land 14A and the second bonding land 14B are substantially the same as the first element electrode 15A and the second element electrode 15B of the light-emitting element 15. Furthermore, a light-emitting element 15 with a long side of 0.95 mm, a short side of 0.75 mm, a thickness of 0.11 mm, and a peak wavelength of 265 nm is prepared (FIG. 7). The light-emitting element 15 includes a single-crystal AlN element substrate SUB and an AlGaN-based light-emitting functional layer LEL on the lower surface of the element substrate SUB, and a rectangular first element electrode 15A and a rectangular second element electrode 15B on the lower surface of the light-emitting functional layer LEL. The upper surface of the element substrate SUB has a thickness of δ - The -c plane is where polarized N atoms are arranged.

[0038] (Element bonding process: S10) The element bonding process is a process of bonding the element electrodes (15A, 15B) of the light-emitting element 15 to the bonding lands (14A, 14B) of the device substrate 11 via the bonding material 15C. First, a solder paste containing 22 wt% Au-Sn particles that will become the bonding material 15C is applied to the surfaces of the bonding lands (14A, 14B) of the device substrate 11 (FIG. 7). The application can be performed by screen printing, stamping, potting, or other methods. Next, the light-emitting element 15 is placed so that the corresponding element electrodes (15A, 15B) overlap the bonding lands (14A, 14B) to which the solder paste has been applied. After that, the light-emitting element 15 is heated to 300°C in a reflow furnace to melt and solidify the 22 wt% Au-Sn particles contained in the solder paste, thereby bonding the light-emitting element 15 to the device substrate 11 (FIG. 8). Note that paste components other than Au-Sn volatilize during reflow.

[0039] (1st sealing process: S20) The first sealing step is a step of forming the first sealing member 13A from a fluororesin solution AC obtained by liquefying an amorphous fluororesin with a solvent on the surface of the light emitting element 15 bonded to the device substrate 11 after the element bonding step (S10) and on the upper surface of the device substrate 11 inside the ring member 12. The amorphous fluororesin used for the first sealing member 13A is a fluororesin obtained by cyclic polymerization of BVE having a terminal functional group of -CF3. An organic fluorine solvent is used as the solvent.

[0040] First, a predetermined amount of fluororesin solution AC is dropped onto the upper surface of light-emitting element 15 (FIG. 9). Next, device substrate 11 with amorphous fluororesin solution AC dropped onto the upper surface of light-emitting element 15 is placed on a hot plate, and the lower surface of device substrate 11 is heated at 230°C for 60 minutes. During this time, amorphous fluororesin solution AC spreads from the surface of light-emitting element 15 (the lower surface excluding the upper surface, side surfaces, and element electrodes (15A, 15B)) to the upper surface of the base material inside annular member 12 of device substrate 11, wetting and coating it continuously. At the same time, the solvent of amorphous fluororesin solution AC volatilizes. This operation (solvent drying method) forms first sealing member 13A, which is a thin film of amorphous fluororesin, on the surface of light-emitting element 15 and the upper surface of the base material inside annular member 12 of device substrate 11 (FIG. 10). At this time, the amorphous fluororesin chemically and physically bonds to the upper surface (-c plane of AlN crystal) and side surfaces (m plane and a plane of AlN crystal) of the element substrate SUB of the light emitting element 15, and the upper surface of the base material of the device substrate 11 (AlN ceramic surface).

[0041] (Temporary fixing process: S30) The temporary fixing step is a step of temporarily fixing (adhering) amorphous fluororesin pellets 13BC, which will become second sealing member 13B, to the upper surface of light-emitting element 15 of device substrate 11 that has undergone the first sealing step (S20), using first sealing member 13A as an auxiliary adhesive layer. Amorphous fluororesin pellets 13BC are fluororesin obtained by cyclic polymerization of BVE, whose terminal functional group is -CF3. Furthermore, amorphous fluororesin pellets 13BC are squares with sides of 1.8 mm on the top and bottom, and rectangular pillars with a height of 1.7 mm.

[0042] First, device substrate 11 that has undergone the first sealing step (S20) is placed on sample stage HT of a temporary fixing device, and the underside of device substrate 11 (the surface of mounting electrodes (17A, 17B)) is heated to 120°C to 200°C in an air atmosphere to soften first sealing member 13A (FIG. 11). Next, amorphous fluororesin pellet 13BC is pressed against the upper surface of first sealing member 13A using suction collet 28 with a load of 10 gf to 100 gf for a time period of 1 to 30 seconds so that the center of the bottom surface of amorphous fluororesin pellet 13BC coincides with the center of light emitting element 15 (FIG. 12). This operation (heat-pressure-mounting method) bonds amorphous fluororesin pellet 13BC to first sealing resin 13A. The surface pressure when the amorphous fluororesin pellet 13BC and the first sealing resin 13A are pressed and placed is 1.4 kgf / cm because the element size of the light emitting element 15 is 0.95 mm × 0.75 mm. 2 ~14kgf / cm 2 The first sealing member 13A of the embodiment is well bonded to the light emitting element 15, so the first sealing member 13A does not peel off from the light emitting element 15. In other words, the first sealing member 13A is well bonded to the light emitting element 15, so the amorphous fluororesin pellets 13BC can be bonded (temporarily fixed) to the first sealing member 13A with a high surface pressure. The amorphous fluororesin pellets 13BC temporarily fixed in this manner will not fall off during operations (for example, cooling, transportation, temporary storage) until the next process. Details of the bonding conditions will be described later.

[0043] (Second sealing process: 40) The second sealing step is a step of softening and flowing the amorphous fluororesin pellets 13BC of the device substrate 11 that has been subjected to the temporary fixing step (S30) to cover the upper surface of the light emitting element 15 and the device substrate 11 and form a convex second sealing member 13B.

[0044] First, the device substrate 11 that has undergone the temporary fixing step (S30) is placed in a vacuum oven. The pressure inside the oven is then reduced to several kPa, and the process is then heated at 250°C for four hours to soften and flow the amorphous fluororesin pellets 13BC (FIG. 13), forming the amorphous fluororesin pellets 13BC into a predetermined shape. This process (pellet softening and flow process) forms a convex second sealing resin 13B that covers the first sealing member 13A (FIG. 14). This process ensures that the amorphous fluororesin pellets 13BC adhere well to the first sealing member 13A, preventing the amorphous fluororesin pellets 13BC from falling off or shifting position even during prolonged heating, allowing the second sealing member 13B to be formed into a predetermined shape.

[0045] Furthermore, because the first sealing resin 13A as an adhesive auxiliary layer is formed on the surface of the light-emitting element 15 and on the upper surface of the base material extending to the annular member 12 of the device substrate 11, the softened and fluidized resin of the amorphous fluororesin pellets 13BC can easily wet and spread. Furthermore, as the amorphous fluororesin pellets 13BC soften and flow to cover the first sealing member 13A, they form a weldable adhesive surface with the first sealing member 13A. In other words, the second sealing member 13B adheres (bonds) well to the first sealing member 13A.

[0046] The shape of the amorphous fluororesin pellets 13BC can be selected to match the shape of the molded second sealing member 13B. For example, if the height of the quadrangular prism-shaped amorphous fluororesin pellets 13BC is the same as one side of the base (cube), the second sealing member 13B will be hemispherical, and if the height is greater than one side of the base (rectangular parallelepiped), the second sealing member 13B will be a spheroid with the major axis being the optical axis.

[0047] Furthermore, the shape of the amorphous fluororesin pellets 13BC is not limited to a rectangular prism, but may also be a polygonal prism such as a hexagonal prism or an octagonal prism, a circular cylinder, or a truncated pyramidal polygonal prism or cylinder. For example, if the amorphous fluororesin pellets 13BC are formed into a frustum prism shape, the second sealing member 13B after molding can be bullet-shaped. If the amorphous fluororesin pellets 13BC are formed into an inverted frustum prism shape, the second sealing member 13B after molding can be spherical.

[0048] (Evaluation of adhesion conditions) Next, the adhesive conditions for the amorphous fluororesin pellets 13BC in the temporary fixing step (S30) will be described. The adhesive conditions are shown in the table of Fig. 15. The horizontal column of the table indicates the temperature of the lower surface of the device substrate 11 (the surface temperature of the sample table HT), and the vertical column of the table indicates the load time of the amorphous fluororesin pellets 13BC. The surface pressure during loading was 1.4 kgf / cm 2 The judgment of good (OK: held) or bad (NG: dropped) was made by temporarily fixing the amorphous fluororesin pellet 13BC facing downwards and conducting a drop impact test from a height of 5 cm.

[0049] The evaluation results were as follows: if the undersurface temperature of the device substrate 11 was 120°C, a loading time of 4 seconds or more was acceptable (OK: maintained); if the undersurface temperature of the device substrate 11 was 130°C, a loading time of 2 seconds or more was acceptable; if the undersurface temperature of the device substrate 11 was 140°C, a loading time of 2 seconds or more was acceptable; if the undersurface temperature of the device substrate 11 was 150°C, a loading time of 1 second or more was acceptable; and if the undersurface temperature of the device substrate 11 was 200°C, a loading time of 1 second or more was acceptable. Thus, the higher the undersurface temperature of the device substrate 11, the faster the temporary bonding can be achieved. From the viewpoint of manufacturing time, the undersurface temperature of the device substrate 11 is preferably 150°C or higher. Note that if the undersurface temperature of the device substrate 11 exceeds 200°C, the fluidity of the first sealing member 13A becomes too high, which may cause the amorphous fluororesin pellets 13BC to slide laterally and become misaligned. Therefore, the undersurface temperature of the device substrate 11 is preferably 200°C or lower.

[0050] As described above, the manufacturing method including the first sealing step (S20), the temporary fixing step (S30), and the second sealing step (S40) makes it possible to form a sealing member 13 made of amorphous fluororesin with extremely low adhesiveness in a convex shape on the upper surface of a frameless, flat device substrate 11. Furthermore, even if the sealing member 13 is made of amorphous fluororesin, good adhesion can be achieved between the sealing member 13 and the surface of the light emitting element 15 and the upper surface of the device substrate 11. In other words, a manufacturing method for an ultraviolet light emitting device with high light output and excellent reliability can be provided.

[0051] As described above, the present invention can provide an ultraviolet light emitting device with high optical output and excellent reliability, or a method for manufacturing an ultraviolet light emitting device.

[0052] The present invention is not limited to the above-described embodiment. For example, the element substrate SUB of the light-emitting element 15 may be made of boron nitride (BN) single crystal. Alternatively, it may be made of gallium nitride (GaN) single crystal. However, when GaN is used as the element substrate, the band gap of GaN is 3.4 eV, so the wavelength of the light emitted from the light-emitting functional layer LEL is limited to wavelengths longer than 365 nm.

[0053] Furthermore, the dimensions of each member described above are merely examples.

[0054] The light emitting device of the present invention can be used as a variety of light sources, for example, a light source for a resin curing device, a light source for a sterilization / disinfection device, a sensor light source for a distance measuring device, etc. [Explanation of symbols]

[0055] 10 Light-emitting device 11 Device board 12 Circular member 13 Sealing member 13A First sealing member 13B Second sealing member 13BC amorphous fluororesin pellets 14A First connecting land 14B Second connecting land 15 Light-emitting element 15A First element electrode 15B Second element electrode 15C Joint material 17A First mounting electrode 17B Second mounting electrode 18A First Metal Via 18B Second Metal Via LEL light-emitting functional layer SUB Element substrate

Claims

1. A method for manufacturing a light emitting device comprising: a device substrate having a flat base material, a plurality of bonding lands formed on an upper surface of the flat base material, and a circular member formed on the upper surface of the flat base material at a distance from the plurality of bonding lands and surrounding the plurality of bonding lands; a light emitting element that emits ultraviolet light and is flip-connected to the plurality of bonding lands of the device substrate; and a sealing member made of an amorphous fluororesin that transmits light emitted from the light emitting element and covers the entire light emitting element on the upper surface of the device substrate, The manufacturing method includes: a step of applying a solution of a fluororesin that will become an amorphous fluororesin to an upper surface of the device substrate and a surface of the light emitting element, and volatilizing the solvent to form a first sealing member that is an amorphous fluororesin in a thin film form; a temporary fixing step of softening the first sealing member and pressing an amorphous fluororesin pellet against the first sealing member formed on the upper surface of the light emitting element to bond the amorphous fluororesin pellet to the first sealing member; softening and fluidizing the amorphous fluororesin pellets to form a second sealing member bonded to the first sealing member; A method for manufacturing a light emitting device, comprising:

2. 2. The method for manufacturing a light emitting device according to claim 1, wherein the amorphous fluororesin of the first sealing member and the second sealing member is a thermoplastic resin.

3. The terminal functional group of the amorphous fluororesin of the first sealing member and the second sealing member is —CF ３ 3. The method for manufacturing a light-emitting device according to claim 2, further comprising:

4. 3. The method for manufacturing a light-emitting device according to claim 2, wherein the amorphous fluororesin of the first sealing member and the second sealing member is a fluororesin obtained by cyclic polymerization of perfluoro(4-vinyloxy-1-butene).

5. 2. The method for manufacturing a light emitting device according to claim 1, wherein the light emitting element has an emission wavelength of 200 nm to 300 nm.

6. 6. The method for manufacturing a light emitting device according to claim 5, wherein the light emitting element includes an element substrate made of a wurtzite type AlN single crystal, and at least one of the surfaces of the element substrate that is bonded to the first sealing member is a -c plane.

7. a device substrate including a flat base material, a plurality of bonding lands formed on an upper surface of the flat base material, and a circular member formed on the upper surface of the flat base material at a distance from the plurality of bonding lands and surrounding the plurality of bonding lands; a light emitting element that emits ultraviolet light and is flip-connected to the plurality of bonding lands of the device substrate; a sealing member made of amorphous fluororesin that transmits light emitted from the light-emitting element and covers the entire light-emitting element on the upper surface of the device substrate, the substrate of the device is an AlN ceramic substrate having resistance to ultraviolet light; The light emitting element has a surface in contact with the amorphous fluororesin, the surface being a δ － is a polarized N atomic surface, The sealing member includes a first sealing member made of a thin film of amorphous fluororesin that tightly covers the surface of the light-emitting element and the upper surface of the device substrate within the annular member, and a second sealing member made of a convex amorphous fluororesin that tightly covers the first sealing member, A light emitting device comprising:

8. 8. The light emitting device according to claim 7, wherein the amorphous fluororesin of the first sealing member and the second sealing member is a thermoplastic resin.

9. The terminal functional group of the amorphous fluororesin of the first sealing member and the second sealing member is —CF ３ 9. The light emitting device according to claim 8, comprising:

10. 10. The light emitting device according to claim 9, wherein the amorphous fluororesin of the first sealing member and the second sealing member is a fluororesin obtained by cyclic polymerization of perfluoro(4-vinyloxy-1-butene).

11. 8. The light emitting device according to claim 7, wherein the light emitting element has an emission wavelength of 200 nm to 300 nm.

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