Ultraviolet irradiation apparatus, weeding apparatus, and method for manufacturing ultraviolet irradiation apparatus

Abstract

To provide an ultraviolet irradiation device capable of preventing breakage of a filler covering a flexible printed board on which a light emitting device is mounted.SOLUTION: An ultraviolet irradiation device includes a light emitting device that emits ultraviolet rays, a flexible printed circuit board on which the light emitting device is mounted, and a filler, in which the light emitting device includes a light emitting element that emits ultraviolet rays as an emission wavelength, a package substrate on which the light emitting element is mounted, and a light transmitting cap made of a material that transmits ultraviolet rays, and the filler seals the flexible printed circuit board on which the light emitting device is mounted therein and has a groove on a surface on an upper surface side.SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] The present invention relates to an ultraviolet irradiation device using a semiconductor light-emitting element that emits ultraviolet light. [Background technology]

[0002] A flexible lighting device incorporating a plurality of light-emitting elements that emit visible light is known from Patent Document 1 and other publications. The lighting device in Patent Document 1 has a structure in which a plurality of light-emitting elements are mounted in a row on a long flexible circuit board, and the surrounding area is covered with a cover made of translucent resin. Furthermore, the lighting device in Patent Document 1 has photocatalytic microparticles dispersed in the translucent resin cover. As a result, when ultraviolet light is irradiated, the photocatalyst contained in the cover breaks down dirt on the surface of the cover, thereby suppressing a decrease in illuminance caused by dirt.

[0003] Meanwhile, an ultraviolet irradiation device has been proposed that can sterilize or disinfect water or air by irradiating the water or air with ultraviolet light from a light-emitting element.

[0004] Furthermore, Patent Document 2 proposes a device that irradiates weeds with ultraviolet light to kill the plants or inhibit their growth. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-31077 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-205962 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, the uses of ultraviolet irradiation devices are expanding, including sterilization, disinfection, weed suppression, etc. If a flexible structure could be realized for ultraviolet irradiation devices, like lighting devices that use visible light light-emitting elements, they could be easily deformed and attached to desired locations.

[0007] However, because ultraviolet-emitting semiconductor light-emitting elements are more susceptible to deterioration due to moisture than light-emitting elements that emit visible light, they are sealed in an airtight package made of, for example, glass. Therefore, even if ultraviolet-emitting semiconductor light-emitting elements are mounted on a flexible circuit board and covered with resin like visible-light-emitting elements, bending the flexible circuit board or the covering resin places stress on the package made of, for example, glass, making them prone to breakage.

[0008] The present invention has been made in view of the above circumstances, and has an object to provide a flexible ultraviolet light emitting device in which the glass package that seals the ultraviolet light emitting element is less likely to break. [Means for solving the problem]

[0009] According to the present invention, there is provided an ultraviolet irradiation device including a light-emitting device that irradiates ultraviolet light, a flexible printed circuit board on which the light-emitting device is mounted, and a filler. The light-emitting device includes a light-emitting element that emits ultraviolet light, a package substrate on which the light-emitting element is mounted, and a cap made of a material that transmits ultraviolet light. The filler covers and seals at least the upper surface of the flexible printed circuit board on which the light-emitting device is mounted, and the filler has a groove on the surface on the upper surface of the filler. [Brief explanation of the drawings]

[0010] [Figure 1A] 1 is a perspective view of an ultraviolet irradiation device 1 according to a first embodiment of the present invention. [Figure 1B] FIG. 1 is a plan view of an ultraviolet irradiation device 1 according to a first embodiment. [Figure 1C] FIG. 1 is a side view of an ultraviolet irradiation device 1 according to a first embodiment. [Figure 2] 1 is a cross-sectional view of a semiconductor light-emitting device 11 of an ultraviolet irradiation device 1 of a first embodiment. [Figure 3A] FIG. 2 is a perspective view of the ultraviolet irradiation device 1 of the first embodiment in a curved state. [Figure 3B] FIG. 2 is a cross-sectional view of the ultraviolet irradiation device 1 of the first embodiment in a curved state. [Figure 4A] FIG. 10 is an explanatory diagram of a curved ultraviolet irradiation device in which no grooves are formed. [Figure 4B] FIG. 10 is an explanatory diagram of a curved ultraviolet irradiation device in which no grooves are formed. [Figure 5] FIG. 2 is a flow diagram illustrating a manufacturing method of the ultraviolet irradiation device 1 of the first embodiment. [Figure 6A] 3A to 3C are explanatory views illustrating a preparation process for the ultraviolet irradiation device 1 of the first embodiment. [Figure 6B] 3A to 3C are explanatory views illustrating a filling step of the ultraviolet irradiation device 1 of the first embodiment. [Figure 6C] 4A to 4C are explanatory views illustrating a cooling process of the ultraviolet irradiation device 1 of the first embodiment. [Figure 6D] 5A to 5C are explanatory views illustrating a hole filling step of the ultraviolet irradiation device 1 of the first embodiment. [Figure 7A] FIG. 10 is a perspective view of an ultraviolet irradiation device 2 according to a second embodiment. [Figure 7B] FIG. 10 is a plan view of an ultraviolet irradiation device 2 according to a second embodiment. [Figure 7C] FIG. 10 is a side view of an ultraviolet irradiation device 2 according to a second embodiment. [Figure 8A] FIG. 10 is a cross-sectional view of a semiconductor light-emitting device 11 of an ultraviolet irradiation device 2 of a second embodiment. [Figure 8B] FIG. 10 is a cross-sectional view of a semiconductor light-emitting device 111 of another example of the ultraviolet irradiation device 2 of the second embodiment. [Figure 9A] FIG. 10 is a perspective view of the ultraviolet irradiation device 2 of the second embodiment when curved. [Figure 9B] FIG. 10 is a cross-sectional view of the ultraviolet irradiation device 2 of the second embodiment when curved. [Figure 9C]FIG. 10 is a cross-sectional view of the ultraviolet irradiation device 2 of the second embodiment when curved. [Figure 10A] 10 is an explanatory diagram illustrating a filling step of the ultraviolet irradiation device 2. FIG. [Figure 10B] FIG. 10 is an enlarged view of the semiconductor light emitting device 11 of the ultraviolet irradiation device 2 of the second embodiment before filling. [Figure 10C] 10 is an enlarged view of the semiconductor light emitting device 11 of the ultraviolet irradiation device 2 according to the second embodiment after filling. FIG. [Figure 11] As a first modification of the second embodiment, a groove 23D is provided on the lower surface side of the ultraviolet irradiation device 2. [Figure 12] As a first modification of the second embodiment, the ultraviolet irradiation device 2 is provided with a backing material 24 for reinforcement. DETAILED DESCRIPTION OF THE INVENTION

[0011] In the following, preferred embodiments of the present invention will be described, but these may be modified and combined as appropriate. In the following description and accompanying drawings, substantially the same or equivalent parts will be denoted by the same reference numerals.

[0012] First Embodiment An ultraviolet irradiation device 1 according to a first embodiment will be described.

[0013] Fig. 1A is a perspective view of an ultraviolet irradiation device 1 according to a first embodiment of the present invention, Fig. 1B is a plan view of the ultraviolet irradiation device 1, and Fig. 1C is a side view of the ultraviolet irradiation device 1. Fig. 2 is a cross-sectional view schematically showing a cross section of a semiconductor light-emitting device 11. Figs. 3A to 3C show the ultraviolet irradiation device 1 in a curved state.

[0014] As shown in FIG. 1, an ultraviolet irradiation device 1 of this embodiment includes a semiconductor light emitting device 11, a flexible printed circuit board 12 on which the semiconductor light emitting device is mounted, and a filler 13.

[0015] The semiconductor light emitting device 11 includes a light emitting element 116 that emits light in the ultraviolet wavelength range, a package substrate 11A on which the light emitting element 116 is mounted, and a cap 115 made of a material that transmits ultraviolet light.

[0016] The flexible printed circuit board 12 has the semiconductor light emitting device 11 mounted on the upper surface thereof.

[0017] Filler 13 covers and seals at least the upper surface of flexible printed circuit board 12 on which semiconductor light emitting device 11 is mounted. Here, filler 13 covers and seals the upper and lower surfaces of flexible printed circuit board 12. Semiconductor light emitting device 11 is also covered with filler 13.

[0018] Groove 13A is formed in the surface on the upper side of filler 13. By providing groove 13A in filler 13, even when ultraviolet irradiation device 1 is bent as shown in Figures 3A and 3B, stress is less likely to be applied to semiconductor light emitting device 11, and damage to semiconductor light emitting device 11 can be prevented. Damage to filler 13 itself can also be prevented.

[0019] The detailed configuration of each part and the function of each part during bending will be further explained below.

[0020] (Semiconductor light-emitting device) The semiconductor light emitting device 11 has a housing structure that includes a rectangular package substrate 11A, a dome-shaped light-transmitting cap 115, and a light emitting element 116 housed therein.

[0021] The package substrate 11A is a ceramic substrate with excellent airtightness that does not allow gases to pass through, and is made of, for example, aluminum nitride (AlN), which also has high thermal conductivity. Materials that can be used as the base material of the package substrate 11A include silicon carbide (SiC), which has high thermal conductivity, and white alumina (Al2O3), which has high reflectivity.

[0022] 2, a substrate metal layer 112 is formed on the outer periphery of the package substrate 11A. The substrate metal layer 112 has a structure (W (or Cu) / Ni / Au) in which tungsten (or copper), nickel, and gold are laminated in this order on the package substrate 11A (the Au layer is the outermost layer). Alternatively, a structure (NiCr / Au / Ni / Au) in which nickel chromium, gold, nickel, and gold are laminated can be used. In this embodiment, the notation of metals separated by the symbol / (metal a / metal b / ··· / metal n) indicates that metal a, metal b, ···, and metal n are laminated in this order. The same applies hereinafter.

[0023] The light-transmitting cap 115 is a rectangular, flat, ultraviolet-transmitting member having a hemispherical dome-shaped window 115A for emitting light at the center thereof. Deep ultraviolet light from the light-emitting element 116 disposed within the semiconductor light-emitting device 11 passes through the window 115A and is emitted to the outside. The light-transmitting cap 115 may be made of any material that transmits ultraviolet light, and suitable materials include, for example, quartz glass, borosilicate glass, sapphire glass, and crystalline quartz. In this embodiment, the light-transmitting cap 115 has a hemispherical dome shape formed in the center of the rectangle. However, the window 115A may also be formed in a flat, convex, concave, convex lens, concave lens, or other similar shape.

[0024] Furthermore, in the light-transmitting cap 115, a cap metal layer 114 is fixed to an outer edge portion 115B (a flange portion if the light-transmitting cap is dome-shaped) that extends from the annular edge of the window portion 115A, and the cap metal layer 114 is joined to the substrate metal layer 112 by a joining layer 113. Hereinafter, the three layers of the substrate metal layer 112, the joining layer 113, and the cap metal layer 114 will be referred to as a joining portion 11B. This joining portion 11B maintains airtightness between the package substrate 11A and the light-transmitting cap 115 (space S).

[0025] The cap metal layer 114 may be, for example, a chromium / nickel / gold (Cr / Ni / Au) layer or a titanium / palladium / copper / nickel / gold (Ti / Pd / Cu / Ni / Au) layer (with the Au layer being the outermost layer).

[0026] On the main surface of the package substrate 11A, there are provided a first wiring electrode (e.g., an anode electrode) 117A and a second wiring electrode (e.g., a cathode electrode) 117B, which are wiring electrodes within the semiconductor light emitting device 11. Furthermore, a light emitting element 116, such as a light emitting diode (LED) or a semiconductor laser, is bonded onto the first wiring electrode 117A by a metal bonding layer 118, and the cathode electrode of the light emitting element 116 is electrically connected to the second wiring electrode 117B via a bonding wire 119.

[0027] Furthermore, a protective element (not shown) which is a Zener diode connected to the first wiring electrode 117A and the second wiring electrode 117B is separately provided on the package substrate 11A to prevent electrostatic damage to the light emitting element 116.

[0028] The light emitting element 116 may be, for example, an aluminum gallium nitride (AlGaN) based semiconductor light emitting element (deep ultraviolet LED) in which a semiconductor structure layer including an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer is formed.

[0029] Here, ultraviolet light refers to light with an emission wavelength of 10 nm to 400 nm. Ultraviolet light is classified into three types depending on its wavelength: UVA, UVB, and UVC. Of these, UVC (emission wavelength 100 nm to 280 nm) is also called deep ultraviolet light and has the ability to destroy DNA. In other words, UVC can be expected to have a strong bactericidal effect and a weed-preventing effect on plants.

[0030] Therefore, it is preferable that the light emitting element 116 is a light emitting element including a semiconductor layer made of GaN or AlGaN that emits ultraviolet light with a wavelength of 265 to 415 nm. Specifically, it is possible to use light emitting elements with a central emission wavelength of 265 nm, 275 nm, 355 nm, 365 nm, 385 nm, 405 nm, or 415 nm, but among these, a light emitting element that can irradiate deep ultraviolet light with a wavelength of 265 nm is preferable.

[0031] A first mounting electrode 120A and a second mounting electrode 120B connected to the first wiring electrode 117A and the second wiring electrode 117B, respectively, are provided on the back surface of the package substrate 11A. Specifically, the first wiring electrode 117A and the second wiring electrode 117B are connected to the first mounting electrode 120A and the second mounting electrode 120B via metal vias 121A and 121B, respectively.

[0032] In such a semiconductor light emitting device 11, when a voltage is applied to the first mounting electrode 120A and the second mounting electrode 120B, the light emitting element 116 emits light, and the emitted light from the surface (light extraction surface) of the light emitting element 116 is emitted to the outside through the translucent cap 115.

[0033] However, without being limited to the above, any deep ultraviolet LED may be used as the light emitting element 116. The semiconductor light emitting device is also not limited to the above, and may have any structure as long as it houses a deep ultraviolet LED.

[0034] (flexible printed circuit board) The flexible printed circuit board 12 is a flexible printed circuit (FPC) board in which a base film, which is a thin insulating material made of polyimide or the like, is used as a substrate, and conductor foil 1 is bonded to the substrate. In this embodiment, an example using a long and narrow rectangular FPC will be described.

[0035] 1A and other figures, the flexible printed circuit board 12, together with the semiconductor light emitting device 11 mounted on the upper surface (hereinafter, the opposite surface will be referred to as the lower surface), is entirely covered and sealed in a filler material 13. Wiring (not shown) to the flexible printed circuit board 12 is pulled out to the outside of the filler material 13, allowing for external power supply. In this case, it is desirable that the roots of the wiring are contained and covered inside the filler material 13, thereby preventing breakage. Even when a connector is used instead of wiring, by covering the connector partway inside the filler material 13, stress is less likely to be applied to the connection portion, preventing breakage and other damage. Furthermore, when used outdoors, it is also possible to prevent rainwater from entering the connection portion.

[0036] The number of semiconductor light emitting devices 11 mounted on the flexible printed circuit board 12 is not particularly limited, and may be any number depending on the application, etc. In addition, although the present embodiment shows an example in which the semiconductor light emitting devices 11 are arranged in a row approximately in the center of the flexible printed circuit board 12, this is not necessarily limited to this, and any arrangement such as a grid pattern may be used.

[0037] (filling material) The filler 13 is a light-transmitting sealing member that seals the flexible printed circuit board 12 and the mounted semiconductor light-emitting device 11. The filler 13 transmits the ultraviolet light from the light-emitting element 116 that has passed through the light-transmitting cap 115 and radiates it to the outside. Therefore, it is preferable to select the filler 13 from a material that is resistant to ultraviolet light. In particular, by using a material that transmits the wavelength band of deep ultraviolet light, deterioration of the filler itself can be suppressed.

[0038] Desirable deep-ultraviolet light-transmitting materials include, for example, ultraviolet-resistant acrylic resin, ultraviolet-resistant silicone resin, and amorphous fluororesin. Amorphous fluororesin is particularly suitable for outdoor use because its surface is resistant to dirt. Examples of amorphous fluororesin that can be used include CYTOP (registered trademark).

[0039] In this way, by sealing the flexible printed circuit board 12 and the mounted semiconductor light-emitting device 11 with the filler 13, it is possible to prevent damage, peeling, falling off, contamination, etc. of the semiconductor light-emitting device 11 due to bending, etc., when the ultraviolet irradiation device is used in a harsh environment, such as outdoors.

[0040] The shape of the filler 13 depends on the shape of the flexible printed circuit board 12 to be sealed, but in this embodiment, the filler 13 is a substantially rectangular parallelepiped with rounded corners in the longitudinal direction on the upper surface side of the filler 13. The thickness A of the filler 13 on the upper surface side of the flexible printed circuit board 12 shown in Figures 1B and 1C is, for example, 8 mm to 15 mm. The thickness B of the filler 13 on the lower surface side is, for example, 5 mm to 10 mm. Furthermore, the thickness C from the side surface of the flexible printed circuit board 12 to the side surface of the filler 13 is, for example, 5 mm to 15 mm.

[0041] The filler 13 has one or more grooves 13A formed between adjacent semiconductor light emitting devices 11. In an embodiment of the present invention, the grooves 13A are formed on the upper surface of the flexible printed circuit board 12 in areas where the semiconductor light emitting devices 11 are not mounted. The grooves 13A are formed perpendicular to the direction in which the flexible printed circuit board 12 extends. The grooves 13A are preferably formed symmetrically with respect to the positions where the semiconductor light emitting devices 11 are mounted. This allows the stress generated in one groove 13A when the ultraviolet irradiation device 1 is bent to be absorbed by the other groove 13A formed symmetrically with respect to the light emitting devices 11. Note that the grooves 13A may also be formed between the ends of the flexible printed circuit board 12 and the outermost semiconductor light emitting devices 11. The grooves 13A are recesses formed continuously from both side surfaces to the upper surface of the filler 13, and are formed symmetrically with respect to the semiconductor light emitting devices 11. The width D of the grooves 13A shown in FIG. 1C is, for example, 3 mm to 10 mm, more preferably 5 mm to 8 mm. Furthermore, depth E of groove 13A is desirably at least two-thirds of the height from the upper surface of filler 13 to the mounting surface of semiconductor light emitting device 11, and is, for example, 6 mm to 10 mm. By making depth E of groove 13A at least two-thirds of the height from the upper surface of filler 13 to the mounting surface of semiconductor light emitting device 11, stress on filler 13 can be further reduced. Furthermore, the formation position of groove 13A can be optimally selected based on factors such as the material and thickness of filler 13, the arrangement of semiconductor light emitting device 11, the size of the groove, and the expected bending angle.

[0042] By providing such grooves 13A, filler 13 can prevent damage to itself and semiconductor light-emitting device 11 when bent. An example of ultraviolet irradiation device 1 with grooves 13A formed therein bent upward is shown in FIGS. 3A and 3B, and an example of such device without grooves 13A is shown in FIG. 4A. An example of bending downward is shown in FIG. 4B.

[0043] As shown in FIG. 4A, when the ultraviolet irradiation device 1 is bent upward, compressive stress occurs on the upper surface of the filler 13 and tensile stress occurs on the lower surface. In this case, if the groove 13A shown in FIG. 4A did not exist, unevenness would occur on the upper surface of the filler 13 to which compressive stress is applied, and cracks and breakages could occur on the lower surface to which tensile stress is applied. Furthermore, the internal semiconductor light-emitting device 11 would also be subjected to stress from the surrounding filler 13, leading to damage, peeling, and falling off. When the ultraviolet irradiation device 1 is bent upward, tensile stress occurs on the upper surface of the filler 13 and compressive stress occurs on the lower surface, as shown in FIG. 4B, so the risk of damage is the same.

[0044] 3A and 3B, when the ultraviolet irradiation device 1 having the groove 13A formed therein is bent upward, stress is concentrated at the corner formed by the groove 13A, and the side surfaces of the groove 13A are elastically deformed by compressive stress so as to collapse in the direction toward each other, absorbing the strain. This reduces the tensile stress on the lower surface as well, preventing breakage on the upper and lower surfaces.

[0045] Since stress tends to concentrate in groove 13A, it is suitable to position groove 13A away from the outer peripheral surface of the mounting position of semiconductor light emitting device 11. Also, by positioning groove 13A a predetermined distance away, stress at the mounting position of semiconductor light emitting device 11 can be minimized, and damage can be avoided.

[0046] In the above description, the bending angle is assumed to be up to, for example, about 30 degrees. If the bending angle is greater than this, the semiconductor light emitting device 11 will irradiate the adjacent ultraviolet irradiation device 1 itself, making it impossible to irradiate efficiently.

[0047] (Method of manufacturing a semiconductor light emitting device) FIG. 5 is a flow diagram illustrating a method for manufacturing the ultraviolet irradiation device 1 of this embodiment.

[0048] First, a preparation step is performed (STEP 101). Specifically, a flexible printed circuit board 12 on which a semiconductor light emitting device 11 is mounted is prepared and placed on a lower mold 52 of a filling device. As shown in FIG. 6A, the flexible printed circuit board 12 is supported at multiple points by pins 53 formed on the lower mold 52, and is fixed in a state in which it is floating above the lower mold 52. The wiring W is drawn out of the mold so that its root portion fits inside the filling space F. The position and number of pins may be designed in any way as long as they are supported to an extent that the flexible printed circuit board 12 does not bend.

[0049] Next, the filling step is performed (STEP 102). Specifically, as shown in FIG. 6B, the upper mold 51 and the lower mold of the filling device are aligned to fix the filling space F, and resin is injected into the space F at low pressure and temperature through a gate (not shown). By adjusting the injection pressure and speed of the resin, it is possible to appropriately adjust the extent to which the filler 13 covers the base WR of the wiring W, i.e., the amount of the filling material 13 to be filled.

[0050] Next, a cooling step is performed (STEP 103). Specifically, after the filling device is cooled to 180 to 240°C for about 15 to 30 seconds, the mold is opened and a molded product as shown in Figure 6C is taken out. At this point, pinholes 53A formed by pins 53 used during installation are open on the underside of the molded product.

[0051] Next, a hole filling step is performed (STEP 104). Specifically, as shown in Fig. 6D, the pinholes are filled with a separate filler 13, plugs, or the like to seal the inside. By the above steps 101 to 104, the ultraviolet irradiation device 1 is completed.

[0052] The first embodiment of the present invention has been described above. The ultraviolet irradiation device 1 according to this embodiment can protect the internal substrates and devices even when used in a harsh environment, and can also prevent damage to the inside or the device itself when bent.

[0053] Second Embodiment Next, a second embodiment of the present invention will be described. In all the drawings used to explain the embodiment, the same components are generally designated by the same reference numerals, and repeated explanations will be omitted.

[0054] FIG. 7A is a perspective view of an ultraviolet irradiation device 2 according to a second embodiment of the present invention, FIG. 7B is a plan view of the ultraviolet irradiation device 2, and FIG. 7C is a side view of the ultraviolet irradiation device 2. As shown in the figures, the ultraviolet irradiation device 2 of this embodiment differs from the first embodiment in that it includes a recess 23A around the semiconductor light-emitting device 12. The recess 23A has an inverted cone shape with the semiconductor light-emitting device 11 at its apex, and is a space open in the direction of light emission from the semiconductor light-emitting device 11. In other words, the window 115A of the semiconductor light-emitting device 12 is exposed from the filler 23. This allows the semiconductor light-emitting device 12 to emit light directly to the outside, with almost no light passing through the filler 23.

[0055] The diameter of the recess 23A is, for example, 15 mm to 20 mm, and more preferably, is an opening that matches the directivity angle of the LED used.

[0056] In such an ultraviolet irradiation device 2, the filler 23 does not necessarily need to transmit deep ultraviolet light, and therefore, a material that absorbs deep ultraviolet light can be used in addition to a material that transmits deep ultraviolet light. Examples of such materials include liquid silicone rubber (LIM material). A reflective material is provided on the conical side surface 23B of the recess. The reflective material can be provided by, for example, coating, pasting, vapor deposition, or the like, and examples of the material that can be used include crystalline fluororesin (PTFE: polytetrafluoroethylene), aluminum, and the like.

[0057] Furthermore, the filler 23 itself may be made of a material that reflects deep ultraviolet light, and no reflective material may be provided. For example, crystalline fluororesin (PTFE) or the like may be used as the material.

[0058] FIG. 8A is an enlarged view of the semiconductor light-emitting device 11 located at the apex of the recess 23A. FIG. 8B is an enlarged view of a semiconductor light-emitting device 111, another example of a semiconductor device. As shown in the figure, in the semiconductor light-emitting device 11 or 111, the filler 23 covers at least a portion (in this example, halfway) of the side surface of the package substrate 11A. More preferably, the filler 23 covers the side surface from the top surface of the flexible printed circuit board 12 to the periphery of the substrate 11, and covers the first mounting electrode 121A and the second mounting electrode 120B. This allows the filler 23 to protect the joint between the flexible printed circuit board 12 and the semiconductor light-emitting device 11 / 111. In this embodiment, the filler 23 does not contact the joint 11B or the cap 115, leaving them exposed. However, this is not necessarily the case; it is also possible to cover the area from the substrate 11A to the joint 11B to protect them. On the other hand, in order not to prevent light irradiation, it is desirable that at least the window portion 115A on the top surface of the light-transmitting cap 115 / 1151 is not in contact with the filler 23. Furthermore, by also exposing the outer edge portion 115B and preventing the filler 23 from contacting the entire light-transmitting cap 115, it is possible to prevent the inflexible light-transmitting cap from being damaged by stress.

[0059] 9A, 9B, and 9C show examples of such a curved ultraviolet irradiation device 2. The effect of groove 13A is the same as in the first embodiment, but in this embodiment, recess 23A further distributes stress, making it possible to prevent damage to semiconductor light emitting device 111.

[0060] Next, a method for manufacturing the ultraviolet irradiation device 2 will be described. FIG. 10A is an explanatory diagram illustrating the filling process of the ultraviolet irradiation device 1, FIG. 10B is an enlarged view of the semiconductor light-emitting device 11 before filling, and FIG. 10C is an enlarged view of the semiconductor light-emitting device 11 after filling. As shown in the figure, the upper mold 61 has a concave cavity 61A at the apex of the conical protrusion for forming the recess 23A. The cavity 61A is designed to accommodate the semiconductor light-emitting device 11 when the upper mold 61 and the lower mold 62 are mated during filling. Furthermore, during filling, a gap G is formed between the edge of the cavity 61A and the flexible printed circuit board 12. The resin injected into the filling space F leaks from the gap G into the cavity 61A, forming a leakage portion 23C that covers the side surface of the package substrate 11A to an appropriate height. The height (amount) of the leakage portion 23C can be optimized by adjusting the size of the gap G, the pressure in the filling space F, the hardness of the filler, the filling time, etc.

[0061] It is desirable that the shape of cavity 61A be similar to and larger than the periphery of package substrate 11A so that leakage portion 23C uniformly covers the periphery of package substrate 11A.

[0062] The second embodiment of the present invention has been described above. According to the ultraviolet irradiation device 2 of this embodiment, the recess 23A is formed, which allows for more intense deep ultraviolet light to be irradiated and prevents damage to the semiconductor light emitting device 11 due to stress when bending.

[0063] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and modifications, and can be embodied in various forms without departing from the spirit of the present invention.

[0064] (Variation 1) FIG. 11 shows an example in which a groove 23D is provided on the underside of the ultraviolet irradiation device 2. As shown in the figure, the groove 23D is formed symmetrically with the groove 13A across the flexible printed circuit board 12. This allows the groove portion to bend more reliably when the device is bent, making the semiconductor light-emitting device 11 less susceptible to stress and preventing damage. Specifically, when the ultraviolet irradiation device 1, in which the groove 13A is formed, is bent downward, the tensile stress causes the side surfaces of the groove 13A to elastically deform and open. At this time, the formation of the groove 23D reduces the compressive stress on the underside as well, preventing damage on the top and bottom surfaces. In this way, by dispersing stress through the grooves 13A and 23D, fracture origins are less likely to occur, preventing damage to the filler 13 itself and the internal substrates and devices.

[0065] (Variation 2) FIG. 12 shows an example in which a backing material 24 is provided for reinforcement in an ultraviolet irradiation device 2. As shown in the figure, a flexible printed circuit board 22 having a backing material 24 on its underside is used on the back side of a semiconductor light-emitting device 11. The backing material 24 is, for example, a flat plate made of stainless steel, polyethylene terephthalate (PET), polyimide, or glass nonwoven fabric, and is provided on the underside of the flexible printed circuit board 22 on which the semiconductor light-emitting device is placed. This further stabilizes the area around the semiconductor light-emitting device 11 and prevents damage due to bending. Furthermore, if the backing material 24 is made of metal, it will have excellent heat dissipation properties and will be able to be used stably.

[0066] (others) Alternatively, for example, a separate lens may be attached to the semiconductor light-emitting device 11 of the ultraviolet irradiation device 2 to control the distribution of spot light, wide light, etc. Also, a photocatalytic material may be added to the conical side surface 23B of the recess 23A. When the conical side surface 23B is exposed to ultraviolet light, dirt on the surface is decomposed by the photocatalytic action.

[0067] The ultraviolet irradiation device 2 described above can be used, for example, as a sterilization device or a weed control device. In particular, although weed control devices are generally installed and used outdoors, the ultraviolet irradiation device of the present invention is useful because it is resistant to damage even when used in harsh environments. [Explanation of symbols]

[0068] 1, 2...ultraviolet irradiation device, 11...semiconductor light emitting device, 12...flexible printed circuit board, 13, 23...filler, 13A, 25D...groove, 23A...recess, 23C...leakage portion.

Claims

1. A light-emitting device that irradiates ultraviolet light, a flexible printed circuit board on which the light-emitting device is mounted, and a filler material, the light emitting device includes a light emitting element that emits light in the ultraviolet wavelength range, a package substrate on which the light emitting element is mounted, and a cap made of a material that transmits ultraviolet light; The filler covers and seals at least the upper surface of the flexible printed circuit board on which the light emitting device is mounted, and the filler has a groove on the surface on the upper surface side of the filler. An ultraviolet irradiation device characterized by:

2. The flexible printed circuit board and the filler are bendable at the position of the groove in a direction that brings both side surfaces of the groove closer to each other and in a direction that moves both side surfaces of the groove apart from each other.

2. The ultraviolet irradiation device according to claim 1.

3. A recess in which the light emitting device is disposed is provided on the upper surface of the filling material, and at least a window portion of the cap for emitting light is exposed without being covered by the filling material.

2. The ultraviolet irradiation device according to claim 1.

4. In addition to the window portion of the cap, the outer edge portion is also exposed without being covered with the filler material.

4. The ultraviolet irradiation device according to claim 3.

5. The filling material covers at least a portion of the package substrate of the light emitting device in the recess.

5. The ultraviolet irradiation device according to claim 3 or 4.

6. a plurality of the grooves are formed symmetrically with respect to the light emitting device in a main plane direction of the flexible substrate; the depth of the groove is equal to or greater than two-thirds of the height from the upper surface of the filler to the mounting surface of the flexible printed circuit board on which the light emitting device is mounted; 4. The ultraviolet irradiation device according to claim 1 or 3.

7. The wavelength of ultraviolet light is between 265 nm and 415 nm.

4. The ultraviolet irradiation device according to claim 1 or 3.

8. The filler is made of a material that transmits ultraviolet light.

3. The ultraviolet irradiation device according to claim 1 or 2.

9. The filler is silicone rubber.

3. The ultraviolet irradiation device according to claim 1 or 2.

10. The filler is an amorphous fluororesin.

3. The ultraviolet irradiation device according to claim 1 or 2.

11. A reflective material that reflects ultraviolet light in a wavelength band is provided on the surface of the recess.

4. The ultraviolet irradiation device according to claim 3.

12. The filler is made of a material that reflects ultraviolet light.

4. The ultraviolet irradiation device according to claim 3.

13. The filler is a crystalline fluororesin.

12. The ultraviolet irradiation device according to claim 11.

14. The filler also covers the lower surface of the flexible printed circuit board, and the filler also has grooves on the surface on the lower surface side.

4. The ultraviolet irradiation device according to claim 1 or 3.

15. A backing material is disposed on the lower surface of the flexible printed circuit board at a position facing the light emitting device with the flexible printed circuit board sandwiched therebetween.

4. The ultraviolet irradiation device according to claim 1 or 3.

16. A lens is further provided on the upper part of the light emitting device.

4. The ultraviolet irradiation device according to claim 1 or 3.

17. A weed control device comprising the ultraviolet irradiation device according to claim 1 or 3.

18. a step of placing a flexible printed circuit board on which a light emitting device is mounted in a filling device; filling a filler material to seal at least the top surface of the flexible printed circuit board; In the step of sealing the flexible printed circuit board, a recess is formed in the filler at a position where the light emitting device is disposed, The light emitting device is located in a recess in the filling material, and a window portion for emitting light from a cap that seals a light emitting element of the light emitting device is exposed without being covered by the filling material. A method for manufacturing an ultraviolet irradiation device, comprising:

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