Light source and wiring board

Abstract

A light source and a wiring board that can be individually driven and controlled and have high heat dissipation properties are provided. [Solution] The light source includes a wiring board having a conductor layer and a first insulating layer disposed on the upper surface of the conductor layer, the wiring board including first, second, third, and fourth wiring disposed on the first insulating layer, and a first light-emitting device and a second light-emitting device disposed on the upper surface of the wiring board. The third wiring and the fourth wiring are electrically connected to the conductor layer. The first light-emitting device includes a first anode and a first cathode. The second light-emitting device includes a second anode and a second cathode. The first anode is electrically connected to the first wiring, the first cathode and the second anode are electrically connected to the second wiring, and the second cathode is electrically connected to the third wiring.

Description

[Technical Field]

[0001] The present disclosure relates to a light source and a wiring substrate. [Background technology]

[0002] A light source has been developed in which a plurality of light-emitting elements are arranged in a grid pattern on a substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2017-502515 Summary of the Invention [Problem to be solved by the invention]

[0004] An embodiment of the present invention provides a light source and a wiring board that can be individually driven and controlled and have high heat dissipation properties. [Means for solving the problem]

[0005] A light source according to one embodiment of the present disclosure includes a wiring substrate having a conductor layer and a first insulating layer disposed on an upper surface of the conductor layer, the wiring substrate including first, second, third, and fourth wirings disposed on the first insulating layer, and a first light-emitting device and a second light-emitting device disposed on the upper surface of the wiring substrate. The third and fourth wirings are electrically connected to the conductor layer. The first light-emitting device includes a first anode and a first cathode. The second light-emitting device includes a second anode and a second cathode. The first anode is electrically connected to the first wiring, the first cathode and the second anode are electrically connected to the second wiring, and the second cathode is electrically connected to the third wiring. [Effects of the Invention]

[0006] According to an embodiment of the present disclosure, it is possible to provide a light source and a wiring board that can be individually driven and controlled and has high heat dissipation properties. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic perspective view of a light source according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 2 is a schematic perspective view showing a partial structure of a light source. [Figure 6] FIG. 6 is an end view taken along line VI-VI in FIG. 5. [Figure 7A] FIG. 6 is an enlarged plan view showing a first unit region U1 in FIG. 5. [Figure 7B] FIG. 6 is an enlarged plan view showing a second unit region U2 in FIG. 5. [Figure 8A] FIG. 1 is a circuit diagram showing one mode of light emission of a light emitting device. [Figure 8B] FIG. 1 is a circuit diagram showing one mode of light emission of a light emitting device. [Figure 8C] FIG. 1 is a circuit diagram showing one mode of light emission of a light emitting device. [Figure 8D] FIG. 1 is a circuit diagram showing one mode of light emission of a light emitting device. [Figure 9] FIG. 10 is a schematic perspective view of a light source according to a modified example. [Figure 10] 10 is a cross-sectional view taken along line XX in FIG. 9. [Figure 11] FIG. 10 is a schematic perspective view of a light source according to a second embodiment. [Figure 12] 12 is a cross-sectional view taken along line XII-XII in FIG. 11. [Figure 13] FIG. 2 is a schematic perspective view showing a partial structure of a light source. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, a light-emitting device and a manufacturing method for a light-emitting device according to an embodiment of the present disclosure will be described with reference to the drawings. The embodiments shown below are intended to exemplify a light-emitting device and a manufacturing method for the same in order to embody the technical concept of the present embodiment, and are not limited thereto. Furthermore, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, etc. of components described in the embodiments are not intended to limit the scope of the present disclosure, but are merely illustrative examples. Note that the size, positional relationship, etc. of components shown in each drawing may be exaggerated for clarity. Furthermore, in the following description, the same names and symbols indicate the same or similar components, and detailed description will be omitted as appropriate. Furthermore, as cross-sectional views, end views showing only the cut surface may be used.

[0009] In the following description, terms indicating specific directions or positions (e.g., "above," "below," and other terms including these terms) may be used. However, these terms are used merely to facilitate understanding of relative directions or positions in the referenced drawings. As long as the relative direction or position relationship indicated by terms such as "above" and "below" in the referenced drawings is the same, the arrangement in drawings other than those disclosed herein, actual products, etc., does not necessarily have to be the same as in the referenced drawings. In this specification, the positional relationship expressed as "above (or below)" includes, for example, when two components are assumed to exist, a case in which the two components are in contact with each other, and a case in which the two components are not in contact with each other and one component is located above (or below) the other component. Furthermore, a plan view refers to a view from above or below, either directly or through a perspective. Furthermore, in this specification, unless otherwise specified, a component covering an object to be covered includes a case in which the component is in contact with the object to be covered directly and a case in which the component is not in contact with the object to be covered indirectly.

[0010] 1. First Embodiment (1.1.Light source 100) The configuration of the light source 100 according to the present disclosure will be described below. FIG. 1 is a schematic perspective view of the light source 100 according to the first embodiment. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1. FIG. 5 is a schematic perspective view showing a portion of the structure of the light source 100. FIG. 6 is an end view taken along line VI-VI in FIG. 5. FIG. 7A is an enlarged plan view showing the first unit region U1 in FIG. 5. FIG. 7B is an enlarged plan view showing the second unit region U2 in FIG. 5.

[0011] The light source 100 includes a wiring board 10 and a plurality of light emitting devices 20 arranged on the upper surface of the wiring board 10. In a plan view, the wiring board 10 is formed in a rectangular shape, and the plurality of light emitting devices 20 are arranged in a grid pattern on the wiring board 10. In this embodiment, four light emitting devices 20 are arranged along a first direction in a plan view (Y direction in the drawing; hereinafter simply referred to as the Y direction). Furthermore, n light emitting devices 20 (n is a natural number, the same applies hereinafter) are arranged along a second direction (X direction in the drawing; hereinafter simply referred to as the X direction) that is perpendicular to the first direction in a plan view.

[0012] More specifically, the light emitting device 20 includes a first light emitting device 20A, a second light emitting device 20B, a third light emitting device 20C, and a fourth light emitting device 20D. The plurality of light emitting devices 20 are arranged on the upper surface of the wiring substrate 10 along the X direction, with n combinations of the first light emitting device 20A, the second light emitting device 20B, the fourth light emitting device 20D, and the third light emitting device 20C arranged in this order along the Y direction.

[0013] (wiring board 10) The wiring board 10 is a member that supports the light emitting devices 20 and the like. In this embodiment, the planar shape of the wiring board 10 is rectangular, but is not limited to this example and can be various shapes such as circular, elliptical, polygonal such as a hexagon, or polygonal with rounded corners. Among these, a rectangular shape is preferable. The size of the wiring board 10 can be adjusted appropriately depending on the required performance, such as the size and number of the light emitting devices 20 to be placed thereon.

[0014] The wiring board 10 includes a conductor layer 15, a first insulating layer 11 disposed on the upper surface of the conductor layer 15, a second insulating layer 12 disposed on the lower surface of the conductor layer 15, and wiring 30 disposed on the first insulating layer 11. The primary material for the first insulating layer 11 and the second insulating layer 12 is preferably an insulating material that is impervious to light from the light emitting device 20 and external light. Examples of such materials include oxide-based ceramics such as aluminum oxide, silicon oxide, calcium oxide, and magnesium oxide; nitride-based ceramics such as aluminum nitride, silicon nitride, and boron nitride; ceramics such as silicon carbide, mullite, and borosilicate glass; and resins such as phenolic resin, epoxy resin, silicone resin, polyimide resin, BT resin (bismaleimide triazine resin), and polyphthalamide. When using a resin, inorganic fillers such as glass fiber, silicon oxide, titanium oxide, and aluminum oxide may be mixed into the resin as needed. This can improve mechanical strength, reduce the thermal expansion coefficient, and improve light reflectance. The main material of the conductor layer 15 includes metals such as Au, Ag, Cu, Fe, Ti, Pd, Ni, Cr, Pt, W, and Al, and alloys containing these metals.

[0015] (Light emitting device 20) The light-emitting device 20 includes a light-emitting element 22, such as a light-emitting diode, and a light-transmitting member 21 disposed on the light-emitting element 22. The light-emitting element 22 includes, for example, a device substrate made of sapphire or the like and a semiconductor layer formed thereon. Alternatively, the light-emitting element 22 may be a semiconductor element consisting only of a semiconductor layer without a device substrate. The shape of the light-emitting element 22 in a planar view may be a polygon, such as a triangle, a rectangle, or a hexagon. The size of the light-emitting element 22 may be, for example, 100 μm or more and 3000 μm or less on a side in a planar view. Specifically, the light-emitting element 22 may be a square with a side of approximately 600 μm, 1000 μm, 1400 μm, or 1700 μm. Alternatively, the light-emitting element 22 may be a rectangle having long and short sides in a planar view.

[0016] The size, emission wavelength, composition, etc. of each light-emitting element 22 may be the same, or some or all of them may be different. Furthermore, the plurality of light-emitting elements 22 may all be connected in series or in parallel, or may be connected in a mixture of series and parallel.

[0017] The light emitting element 22 includes an n-type semiconductor layer, a p-type semiconductor layer, and a light emitting layer sandwiched between them. The semiconductor laminate including such a light emitting layer is, for example, In x Al y Ga 1-x-y N (0≦x, 0≦y, x+y≦1).

[0018] The light-emitting element 22 may have a structure including one or more light-emitting layers between an n-type semiconductor layer and a p-type semiconductor layer, or may have a structure in which a structure including an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer in that order is repeated multiple times. When the light-emitting element 22 includes multiple light-emitting layers, the light-emitting layers may have different emission peak wavelengths, or may have light-emitting layers with the same emission peak wavelength. Note that the same emission peak wavelength includes cases where the emission peak wavelength varies by a few nanometers. The combination of emission peak wavelengths between the multiple light-emitting layers can be appropriately selected. For example, when the semiconductor laminate includes two light-emitting layers, the light-emitting layers can be selected to emit light of the same color, such as blue light and blue light, green light and green light, red light and red light, or ultraviolet light and ultraviolet light, or to emit light of different colors, such as blue light and green light, blue light and red light, or green light and red light.

[0019] The light emitting device 20 includes at least one pair of electrodes 23 on the underside of the light emitting element 22. In other words, the light emitting device 20 includes at least one anode and at least one cathode as electrodes. As an example, the anode and cathode each have a rectangular shape in a plan view. In this way, when there is only one anode and one cathode, the size of each can be increased, thereby improving heat dissipation.

[0020] Specifically, the first light emitting device 20A includes a first anode 23A1 and a first cathode 23A2 as the first electrode 23A. The second light emitting device 20B includes a second anode 23B1 and a second cathode 23B2 as the second electrode 23B. The third light emitting device 20C includes a third anode 23C1 and a third cathode 23C2 as the third electrode 23C. The fourth light emitting device 20D includes a fourth anode 23D1 and a fourth cathode 23D2 as the fourth electrode 23D.

[0021] The first light emitting device 20A is arranged in a first region R1 on the upper surface of the first insulating layer 11. The second light emitting device 20B is arranged in a second region R2 on the upper surface of the first insulating layer 11. The third light emitting device 20C is arranged in a third region R3 on the upper surface of the first insulating layer 11. The fourth light emitting device 20D is arranged in a fourth region R4 on the upper surface of the first insulating layer 11. The first region R1, the second region R2, the third region R3, and the fourth region R4 are arranged in the Y direction in the order of the first region R1, the second region R2, the fourth region R4, and the third region R3. Furthermore, while maintaining this order, n combinations of the first region R1, the second region R2, the third region R3, and the fourth region R4 are arranged in the X direction.

[0022] The electrode 23 can be made of a good electrical conductor, such as gold, silver, copper, platinum, iron, nickel, tin, or an alloy thereof. The electrode 23 can include an ohmic electrode in contact with the lower surface of the light-emitting element 22 and a pad electrode connected to the ohmic electrode and externally connected. The thickness of the electrode can be, for example, 0.5 μm to 50 μm, more preferably 5 μm to 20 μm.

[0023] The light-transmitting member 21 is a member that transmits light emitted from the light-emitting element 22 and releases it to the outside, and is bonded to the upper surface of the light-emitting element 22. The light-transmitting member 21 may transmit 60% or more of the light from the light-emitting element 22 (for example, light with a wavelength in the range of 320 nm to 850 nm), and preferably transmits 70% or more of the light. Furthermore, the light-transmitting member 21 is preferably a plate-shaped member.

[0024] The thickness of the light-transmitting member 21 can be, for example, in the range of 50 μm to 300 μm. The light-transmitting member 21 and the light-emitting element 22 can be bonded together using a light-transmitting adhesive or the like that is commonly used in this field. Alternatively, the light-transmitting member 21 and the light-emitting element 22 may be bonded together using a direct bonding method such as pressure bonding, surface activated bonding, atomic diffusion bonding, or hydroxyl group bonding.

[0025] The light-transmitting member 21 may be formed from any of inorganic materials such as glass, ceramics, sapphire, etc., or organic materials such as resins or hybrid resins containing one or more of silicone resin, modified silicone resin, epoxy resin, modified epoxy resin, acrylic resin, phenolic resin, and fluororesin.

[0026] The light-transmitting member 21 may contain a phosphor or a light diffusing material capable of converting the wavelength of at least a portion of the incident light. Examples of light-transmitting members containing a phosphor include a sintered body of a phosphor, and resin, glass, ceramics, or other inorganic materials containing a phosphor. Alternatively, the light-transmitting member 21 may be a molded body of resin, glass, ceramics, or the like, on the surface of which a resin layer containing a phosphor is formed.

[0027] As the light diffusing material, any of those commonly used in the relevant field, such as titanium oxide, barium titanate, aluminum oxide, silicon oxide, zirconium oxide, aerosil, glass, glass fiber, or fillers such as wollastonite, aluminum nitride, etc. may be used.

[0028] The phosphor used can be one that can be excited by light emitted from the light-emitting element 22. For example, phosphors that can be excited by a blue light-emitting element or an ultraviolet light-emitting element include cerium-activated yttrium-aluminum-garnet phosphors (YAG:Ce), cerium-activated lutetium-aluminum-garnet phosphors (LAG:Ce), nitrogen-containing calcium aluminosilicate phosphors (CaO-Al2O3-SiO2:Eu) activated with europium and / or chromium, europium-activated silicate phosphors ((Sr,Ba)2SiO4:Eu), β-sialon phosphors, nitride-based phosphors such as CASN-based phosphors represented by CaAlSiN3:Eu and SCASN-based phosphors represented by (Sr,Ca)AlSiN3:Eu, KSF-based phosphors represented by K2SiF6:Mn, sulfide-based phosphors, and quantum dot phosphors. By combining these phosphors with a blue light emitting element or an ultraviolet light emitting element, a light emitting device emitting light of a desired color (for example, a white light emitting device) can be manufactured.

[0029] (Wiring 30) The wiring 30 is arranged in a predetermined pattern on the first insulating layer 11 and is electrically connected to the plurality of light emitting devices 20. Examples of materials for the wiring include metals such as Au, Ag, Cu, Fe, Ti, Pd, Ni, Cr, Pt, W, Al, and Sn, and alloys containing these metals. The wiring can be formed by plating, vapor deposition, sputtering, or the like. For example, when Au is used as a bonding member between the light emitting element and the substrate (described later), it is preferable to use Au on the outermost surface of the wiring 30 in order to improve bonding strength.

[0030] The wiring 30 includes a first wiring 31, a second wiring 32, a third wiring 33, a fourth wiring 34, a fifth wiring 35, a sixth wiring 36, and a seventh wiring 37, which are arranged on the first insulating layer 11. The first wiring 31, the second wiring 32, and the third wiring 33 are included in a first unit region U1. The fifth wiring 35, the sixth wiring 36, and the seventh wiring 37 are included in a second unit region U2. The first unit region U1 and the second unit region U2 are arranged in the Y direction in the order of the first unit region U1 and the second unit region U2. Furthermore, while maintaining this arrangement, n combinations of the first unit region U1 and the second unit region U2 are arranged in the X direction.

[0031] In the first unit region U1, the second wiring 32, the first wiring 31, and the third wiring 33 are arranged side by side along the X direction. Specifically, the second wiring 32 is arranged on the negative side in the X direction, the first wiring 31 is arranged on the negative side in the Y direction at the positive side in the X direction, and the third wiring 33 is arranged on the positive side in the X direction at the positive side in the Y direction.

[0032] In the second unit region U2, the sixth wiring 36, the fifth wiring 35, and the seventh wiring 37 are arranged side by side along the X direction. Specifically, the sixth wiring 36 is arranged on the negative side in the X direction, the seventh wiring 37 is arranged on the negative side in the Y direction at the positive side in the X direction, and the fifth wiring 35 is arranged on the positive side in the Y direction at the positive side in the X direction.

[0033] The first wiring 31 includes a pad 31a to which a bonding wire for external electrical conduction is connected, a terminal 31c to which the first anode 23A1 of the first light-emitting device 20A is electrically connected, and a connecting portion 31b for connecting the pad 31a and the terminal 31c. The pad 31a, the connecting portion 31b, and the terminal 31c are arranged in this order along the Y direction. As an example, the pad 31a and the terminal 31c are rectangular in plan view, and the width of the pad 31a along the X direction (hereinafter simply referred to as the width) is approximately the same as the width of the terminal 31c, but this is not limited to this example. Also, as an example, the width of the connecting portion 31b is narrower than the widths of the pad 31a and the terminal 31c, but this is not limited to this example.

[0034] The second wiring 32 includes a pad 32a to which a bonding wire is connected from the outside for conducting electricity, a first terminal 32c1 to which the first cathode 23A2 of the first light-emitting device 20A is electrically connected, a second terminal 32c2 to which the second anode 23B1 of the second light-emitting device 20B is electrically connected, a first connecting portion 32b1 for connecting the pad 32a and the first terminal 32c1, and a second connecting portion 32b2 for connecting the first terminal 32c1 and the second terminal 32c2.

[0035] The pad 32a, the first connecting portion 32b1, the second connecting portion 32b2, the first terminal 32c1, and the second terminal 32c2 are arranged in the Y direction in the following order: pad 32a, first connecting portion 32b1, first terminal 32c1, second connecting portion 32b2, second terminal 32c2. As an example, the pad 32a, the first terminal 32c1, and the second terminal 32c2 are rectangular in plan view, and the width of the pad 32a is approximately the same as the widths of the first terminal 32c1 and the second terminal 32c2, but this is not limited to this example. Also, as an example, the widths of the first connecting portion 32b1 and the second connecting portion 32b2 are narrower than the widths of the pad 32a, the first terminal 32c1, and the second terminal 32c2, but this is not limited to this example.

[0036] The third wiring 33 includes a terminal 33c to which the second cathode 23B2 of the second light-emitting device 20B is electrically connected. As an example, the terminal 33c has a rectangular shape in a plan view, but is not limited to this example. A through hole 16 is formed in the first insulating layer 11 directly below the third wiring 33. A metal member 17 is disposed inside the through hole 16, and the third wiring 33 and the conductor layer 15 are electrically connected via the metal member 17.

[0037] With this configuration, in the first unit region U1, the pad 31a of the first wiring 31, the first anode 23A1 of the first light-emitting device 20A, and the second cathode 23B2 of the second light-emitting device 20B are arranged along the Y direction in a plan view. Also, the pad 32a of the second wiring 32, the first cathode 23A2 of the first light-emitting device 20A, and the second anode 23B1 of the second light-emitting device 20B are arranged along the Y direction.

[0038] At least one fourth wiring 34 is arranged on the wiring substrate 10. As an example, the fourth wiring 34 is arranged at one of the four corners on the upper surface of the wiring substrate 10 (specifically, at the end on the positive side in the X direction and the negative side in the Y direction), but this is not limited to this example. The fourth wiring 34 includes a pad 34a to which a bonding wire having an equipotential with the ground is connected. As an example, the pad 34a has a rectangular shape in a plan view, but this is not limited to this example. A through hole 16 is formed in the first insulating layer 11 directly below the fourth wiring 34. A metal member 17 is arranged inside the through hole 16, and the fourth wiring 34 and the conductor layer 15 are electrically connected via the metal member 17.

[0039] The fifth wiring 35 includes a pad 35a to which a bonding wire for external electrical conduction is connected, a terminal 35c to which the third anode 23C1 of the third light-emitting device 20C is electrically connected, and a connecting portion 35b for connecting the pad 35a and the terminal 35c. The pad 35a, the connecting portion 35b, and the terminal 35c are arranged in the Y direction in the order of terminal 35c, connecting portion 35b, and pad 35a. As an example, the pad 35a and the terminal 35c are rectangular in plan view, and the width of the pad 35a is approximately the same as the width of the terminal 35c, although this is not limited to this example. As an example, the width of the connecting portion 35b is narrower than the widths of the pad 35a and the terminal 35c, although this is not limited to this example.

[0040] The sixth wiring 36 includes a pad 36a to which a bonding wire for conducting electricity from the outside is connected, a first terminal 36c1 to which the third cathode 23C2 of the third light-emitting device 20C is electrically connected, a second terminal 36c2 to which the fourth anode 23D1 of the fourth light-emitting device 20D is electrically connected, a first connecting portion 36b1 for connecting the pad 36a and the first terminal 36c1, and a second connecting portion 36b2 for connecting the first terminal 36c1 and the second terminal 36c2.

[0041] The pad 36a, the first connecting portion 36b1, the second connecting portion 36b2, the first terminal 36c1, and the second terminal 36c2 are arranged in the Y direction in the following order: second terminal 36c2, second connecting portion 36b2, first terminal 36c1, first connecting portion 36b1, pad 36a. As an example, the pad 36a, the first terminal 36c1, and the second terminal 36c2 are rectangular in plan view, and the width of the pad 36a is approximately the same as the width of the first terminal 36c1 and the second terminal 36c2, but this is not limited to this example. Also, as an example, the widths of the first connecting portion 36b1 and the second connecting portion 36b2 are narrower than the widths of the pad 36a, the first terminal 36c1, and the second terminal 36c2, but this is not limited to this example.

[0042] The seventh wiring 37 includes a terminal 37c to which the fourth cathode 23D2 of the fourth light-emitting device 20D is electrically connected. As an example, the terminal 37c has a rectangular shape in a plan view, but is not limited to this example. A through hole 16 is formed in the first insulating layer 11 directly below the seventh wiring 37. A metal member 17 is disposed inside the through hole 16, and the seventh wiring 37 and the conductor layer 15 are electrically connected via the metal member 17.

[0043] With this configuration, in the second unit region U2, the fourth cathode 23D2 of the fourth light emitting device 20D, the third anode 23C1 of the third light emitting device 20C, and the pad 35a of the fifth wiring 35 are arranged along the Y direction in a plan view. Also, the fourth anode 23D1 of the fourth light emitting device 20D, the third cathode 23C2 of the third light emitting device 20C, and the pad 36a of the sixth wiring 36 are arranged along the Y direction.

[0044] (1.2. Light Emission Control) 8A to 8D, light emission control in light source 100 will be described. Figures 8A to 8D are circuit diagrams showing one mode of light emission of light emitting device 20. Below, light emission control of first light emitting device 20A and second light emitting device 20B in first unit region U1 will be described, but light emission control of third light emitting device 20C and fourth light emitting device 20D in second unit region U2 can be similarly controlled.

[0045] As described above, the first light emitting device 20A is electrically connected to the terminal 31c of the first wiring 31 and the first terminal 32c1 of the second wiring 32. The second light emitting device 20B is electrically connected to the second terminal 32c2 of the second wiring 32 and the terminal 33c of the third wiring 33. The third wiring is electrically connected to the conductor layer 15, and the conductor layer 15 is connected to ground via the fourth wiring 34. In the following description, the potential of the first wiring 31 is referred to as a first potential V1, and the potential of the second wiring 32 is referred to as a second potential V2.

[0046] 8A, when the first potential V1 is set to Low (a potential similar to ground) and the second potential V2 is set to Low, no potential difference (voltage) occurs between the terminal 31c of the first wiring 31 and the first terminal 32c1 of the second wiring 32, and therefore no current flows through the first light-emitting device 20A. Furthermore, no potential difference occurs between the second terminal 32c2 of the second wiring 32 and the terminal 33c of the third wiring 33, and therefore no current flows through the second light-emitting device 20B. Therefore, neither the first light-emitting device 20A nor the second light-emitting device 20B emits light.

[0047] 8B, when the first potential V1 is set to High (a potential higher than Low by at least the forward voltage Vf of the light-emitting element 22), and the second potential V2 is set to Low, a potential difference occurs between the terminal 31c of the first wiring 31 and the first terminal 32c1 of the second wiring 32, causing a current to flow through the first light-emitting device 20A. On the other hand, no potential difference occurs between the second terminal 32c2 of the second wiring 32 and the terminal 33c of the third wiring 33, causing no current to flow through the second light-emitting device 20B. Therefore, only the first light-emitting device 20A emits light.

[0048] 8C, when the first potential V1 is set to High and the second potential V2 is set to High, no potential difference occurs between the terminal 31c of the first wiring 31 and the first terminal 32c1 of the second wiring 32, and therefore no current flows through the first light-emitting device 20A. On the other hand, a potential difference occurs between the second terminal 32c2 of the second wiring 32 and the terminal 33c of the third wiring 33, and therefore a current flows through the second light-emitting device 20B. Therefore, only the second light-emitting device 20B emits light.

[0049] 8D, when the first potential V1 is set to High and the second potential V2 is set to Open (the terminals are not connected), a potential difference occurs between the terminal 31c of the first wiring 31 and the terminal 33c of the third wiring 33, causing a current to flow through the first light-emitting device 20A and the second light-emitting device 20B. As a result, both the first light-emitting device 20A and the second light-emitting device 20B emit light.

[0050] (1.3.Summary) As described above, light source 100 according to this embodiment includes conductor layer 15, first insulating layer 11 disposed on the upper surface of conductor layer 15, wiring substrate 10 having first wiring 31, second wiring 32, third wiring 33, and fourth wiring 34 disposed on first insulating layer 11, and first light emitting device 20A and second light emitting device 20B disposed on the upper surface of wiring substrate 10. Third wiring 33 and fourth wiring 34 are electrically connected to conductor layer 15. First light emitting device 20A includes first anode 23A1 and first cathode 23A2, and second light emitting device 20B includes second anode 23B1 and second cathode 23B2. The first anode 23A1 is electrically connected to the first wiring 31, the first cathode 23A2 and the second anode 23B1 are electrically connected to the second wiring, and the second cathode 23B2 is electrically connected to the third wiring. With this configuration, the wiring substrate 10 includes the conductor layer 15 having high thermal conductivity, and multiple wirings can be arranged on the upper surface of the wiring substrate 10, making it possible to provide a high-density light source that can be individually driven and controlled and has high heat dissipation properties.

[0051] Alternatively, in plan view, the first wiring 31 and the second wiring 32 may be arranged side by side in a second direction (X direction) perpendicular to the first direction (Y direction), the pad 31a of the first wiring 31, the first anode 23A1 of the first light-emitting device 20A, and the second cathode 23B2 of the second light-emitting device 20B may be arranged along the Y direction, and the pad 32a of the second wiring 32, the first cathode 23A2 of the first light-emitting device 20A, and the second anode 23B1 of the second light-emitting device 20B may be arranged along the Y direction. Such a configuration enables light emission control to cause either or both of the first light-emitting device 20A and the second light-emitting device 20B to emit light.

[0052] The wiring board 10 may further include a second insulating layer 12 disposed on the lower surface of the conductor layer 15. With this configuration, it becomes easier to control the potential of the conductor layer 15 and maintain it at, for example, ground.

[0053] Furthermore, the first insulating layer 11 has a plurality of through holes 16, and metal members 17 are disposed inside the through holes 16, and the third wiring 33 and the fourth wiring 34 may be electrically connected to the conductor layer 15 via the metal members 17 disposed inside the through holes 16. With this configuration, the third wiring 33 and the fourth wiring 34 can be electrically connected to the conductor layer 15 with a simple structure, and the cost required for installing the wiring can be reduced.

[0054] The light source 100 may further include a third light emitting device 20C and a fourth light emitting device 20D arranged on the upper surface of the wiring substrate 10. In this case, the wiring substrate 10 further includes a fifth wiring 35, a sixth wiring 36, and a seventh wiring 37 arranged on the first insulating layer 11. The seventh wiring 37 is electrically connected to the conductor layer 15 via a metal member 17 arranged inside the through hole 16. The first light emitting device 20A, the second light emitting device 20B, the fourth light emitting device 20D, and the third light emitting device 20C are arranged along the Y direction. The third light emitting device includes a third anode 23C1 and a third cathode 23C2, and the fourth light emitting device includes a fourth anode 23D1 and a fourth cathode 23D2. The third anode 23C1 is electrically connected to the fifth wiring 35, the third cathode 23C2 and the fourth anode 23D1 are electrically connected to the sixth wiring 36, and the fourth cathode 23D2 is electrically connected to the seventh wiring 37. With this configuration, it is possible to arrange even more light emitting devices 20, and provide a light source that is high in density, can be driven and controlled individually, and has high heat dissipation properties.

[0055] (1.4. Variations) A light source 150 according to a modified example of the first embodiment will be described with reference to Figs. 9 and 10. The following description will focus on differences from the first embodiment. Fig. 9 is a schematic perspective view of the light source according to the modified example. Fig. 10 is a cross-sectional view taken along line XX in Fig. 9.

[0056] The light source 150 according to the modified example further includes a base substrate 210 and a covering member 50. The base substrate 210 includes a flat substrate and a second terminal 62 disposed on the upper surface of the substrate. The base substrate 210 has a substrate mounting area on its upper surface on which the wiring substrate 10 is mounted.

[0057] The second terminal 62 is connected by a wire 70 to a first terminal 61 arranged on the wiring 30 on the upper surface of the wiring substrate 10. Here, as an example, the first terminal 61 and the second terminal 62 are each approximately rectangular and arranged spaced apart from each other in a line along the X direction. The interval at which the first terminals and the second terminals are aligned may be 50 μm or more and 200 μm or less. The first terminals and the second terminals may be formed, for example, using the same material and method as the wiring of the wiring substrate 10 already described.

[0058] The base material of the base substrate 210 is preferably made of a material with high heat dissipation properties, and more preferably, a material with high light-shielding properties and base material strength. Specific examples include oxide-based ceramics such as aluminum oxide, silicon oxide, calcium oxide, and magnesium oxide; nitride-based ceramics such as aluminum nitride, silicon nitride, and boron nitride; ceramics such as silicon carbide, mullite, and borosilicate glass; resins such as phenolic resin, epoxy resin, polyimide resin, BT resin, and polyphthalamide; and composite materials composed of resin and metal or ceramic. The base substrate may be flat, or may have a cavity on its upper surface. In this case, the base substrate 210 can have the bottom of the cavity as a substrate mounting area, and the wiring substrate 10 can be mounted within the cavity. The base substrate 210 may have wiring on the surface of the substrate mounting area for mounting the wiring substrate 10. The wiring substrate 10 and the base substrate 210 can be bonded via a bonding material such as an Ag sintered body, solder, or adhesive resin.

[0059] Examples of the wire 70 include conductive wires made of metals such as gold, copper, platinum, and aluminum, and / or alloys containing at least these metals. Gold is particularly preferred because of its excellent thermal resistance. The diameter of the wire can be, for example, 10 μm or more and 50 μm or less.

[0060] The covering member 50 is a light-blocking resin that covers the wire 70 outside the plurality of light emitting devices 20 in a plan view. The covering member 50 is arranged so as to be in contact with a first protrusion 41, which will be described later. The covering member 50 has a width greater on the long side of the rectangle of the wiring board 10, which is generally rectangular in a plan view, than on the short side. Furthermore, the covering member 50 is arranged so that its height (i.e., the distance from the top surface of the base substrate 210 to the top surface of the covering member 50) is greatest directly above the top of the wire 70 (here, the loop top of the wire 70). The top of the covering member 50 is arranged so as to be located higher than the top of the first protrusion 41, which will be described later.

[0061] Examples of the light-blocking covering member 50 include resins containing a light-blocking filler. Examples of the base resin include silicone resin, modified silicone resin, epoxy resin, modified epoxy resin, and acrylic resin. Examples of the light-blocking filler include light-absorbing materials such as pigments, carbon black, and graphite, as well as light-reflecting materials similar to the light-reflecting materials contained in the reflective members described above. Specific examples include white resins with excellent light reflectivity, black resins with excellent light absorption, and gray resins with both light reflectivity and light absorption. The covering member 50 may also be formed by laminating multiple layers of these resins. In particular, considering the deterioration of the resin due to light absorption, it is preferable to use a light-reflective white resin on at least the outermost surface of the covering member 50.

[0062] The light source 150 has a light-transmitting first convex portion 41 on the wiring substrate 10 that contacts the covering member 50. Furthermore, the light source 150 has a second convex portion 42 that is arranged on the upper surface of the base substrate 210, outside the second terminal 62, and that contacts the covering member 50. In other words, the covering member 50 is arranged between the first convex portion 41 and the second convex portion 42, spanning from the upper surface of the wiring substrate 10 to the upper surface of the base substrate 210.

[0063] The covering member 50 is disposed between the first convex portion 41 on the wiring substrate 10 and the second convex portion 42 on the base substrate 210. Such an arrangement of the covering member 50 can be formed by supplying the uncured resin that constitutes the covering member 50 into a frame surrounded by the first convex portion 41 and the second convex portion 42. In other words, the first convex portion 41 and the second convex portion 42 can be used as a dam to block the flow of the uncured resin when the covering member 50 is supplied.

[0064] The first convex portion 41 and the second convex portion 42 can be formed to a predetermined height by providing a plurality of layers of uncured resin in the height direction. For example, the first convex portion 41 and the second convex portion 42 may be formed to a predetermined height by disposing a single layer of resin adjusted to a predetermined viscosity from a nozzle on the substrate and repeating this process.

[0065] The first protrusion 41 is disposed on the wiring substrate 10 so that its top is located above the light-emitting device 20. The height of the first protrusion 41 from the top surface of the wiring substrate 10 may be the same as or different from the height of the second protrusion 42 from the top surface of the base substrate 210. If the heights are different, it is preferable that the second protrusion 42 be higher than the first protrusion 41. In this case, the difference between the height from the top surface of the base substrate 210 to the top of the first protrusion 41 and the height from the top surface of the base substrate 210 to the top of the second protrusion 42 can be made smaller than the thickness of the wiring substrate 10 (i.e., the distance from the top surface to the bottom surface of the wiring substrate 10). This makes it possible to prevent the uncured covering member 50 from spilling out of the second protrusion 42 when the covering member 50 is disposed between the first protrusion 41 and the second protrusion 42.

[0066] The resins exemplified above as the base material of the covering member can be used for the first convex portions 41 and the second convex portions 42. It is preferable that the resin forming the first convex portions 41 and the second convex portions 42 has a higher viscosity than the resin forming the covering member 50. The viscosity of the resin can be adjusted, for example, by the amount of viscosity-adjusting filler contained in the resin.

[0067] The first protrusion 41 is translucent to light emitted from the light emitting device 20. The first protrusion 41 can be made of a resin material having optical transparency and insulating properties, such as a thermosetting resin such as an epoxy resin or a silicone resin. The first protrusion 41 is arranged in a rectangular frame shape in a plan view. For example, the covering member 50 is arranged so as to contact the top of the first protrusion 41. The first protrusion 41 is arranged on the wiring substrate 10 in a rectangular frame shape in a plan view along the periphery of an area where the plurality of light emitting devices 20 are arranged (hereinafter also referred to as the arrangement area). The first protrusion 41 is arranged between a longitudinal side of the arrangement area and the plurality of first terminals 61 along the longitudinal direction of the arrangement area. Furthermore, the first protrusion 41 is arranged on the wiring substrate 10 between the arrangement area and the outer edge of the first substrate along the lateral direction of the arrangement area.

[0068] The first convex portion 41 preferably has an inclined surface that slopes from the substrate side toward the top of the first convex portion 41. The inclined surface is preferably a curved surface that is convex outward, and specifically, the first convex portion 41 preferably has a semicircular or semi-elliptical cross-sectional shape. This allows the surface of the covering member 50 that contacts the first convex portion 41 to be a curved surface that is convex toward the covering member 50. By having the covering member 50 have such a surface shape, light that is emitted from the light emitting device 20, passes through the first convex portion 41, and heads toward the covering member 50 can be reflected toward the wiring substrate 10. This prevents unintended leakage light and stray light from heading upward (toward the light extraction side), resulting in a light emitting module with reduced light scattering.

[0069] The second convex portion 42 is disposed below the light emitting device 20 in the light emitting module (i.e., on the opposite side to the light extraction side). Therefore, the second convex portion 42 may or may not be translucent to the light emitted from the light emitting device 20. The second convex portion 42 can be used as a dam for blocking the uncured covering member 50 in the manufacturing process, similar to the first convex portion 41. Therefore, it is preferable that the second convex portion 42 be disposed in the same process as the first convex portion 41 or in a subsequent process, and from the viewpoint of simplifying the manufacturing method, it is preferable that a translucent resin be used for the second convex portion 42, similar to the first convex portion 41.

[0070] 2. Second Embodiment A light source 200 according to a second embodiment of the present disclosure will be described with reference to Figs. 11 to 13. The following description will focus on differences from the first embodiment. Fig. 11 is a schematic perspective view of the light source 200 according to the second embodiment. Fig. 12 is a cross-sectional view taken along line XII-XII in Fig. 11. Fig. 13 is a schematic perspective view showing the structure of a portion of the light source 200.

[0071] The light source 200 according to the second embodiment differs from the first embodiment in that three light emitting devices 20 are arranged along the Y direction. Specifically, the light emitting device 20 includes a first light emitting device 20A, a second light emitting device 20B, and a third light emitting device 20C. The light emitting devices 20 are arranged on the upper surface of the wiring substrate 10 in the X direction, with n combinations of the first light emitting device 20A, the second light emitting device 20B, and the third light emitting device 20C arranged in this order along the Y direction.

[0072] Wiring 30 is disposed on the first insulating layer 11. The wiring 30 includes a first wiring 31, a second wiring 32, a third wiring 33, a fourth wiring 34, a fifth wiring 35, and a sixth wiring 36. The first wiring 31 to the fifth wiring 35 are the same as those in the first embodiment. Meanwhile, the sixth wiring includes a pad 36a to which a bonding wire for conducting electricity from the outside is connected, a terminal 36c to which the third cathode 23C2 of the third light-emitting device 20C is electrically connected, and a connecting portion 36b for connecting the pad 36a and the terminal 36c. The fifth wiring 35 and the sixth wiring 36 are disposed side by side along the X direction.

[0073] In this way, even in a light source 200 in which three light emitting devices 20 are arranged along the Y direction, the wiring board 10 is provided with a conductor layer 15 having high thermal conductivity, and wiring can be arranged on the upper surface of the wiring board 10, which can be individually driven and controlled, making it possible to provide a low-cost light source with high heat dissipation properties.

[0074] <3. Other embodiments> Although the embodiments of the present disclosure have been described above, they are not limited to the above. For example, in the above embodiment, a light source 100 to which the technical concept of the present disclosure is applied has been described. However, the technical concept of the present disclosure may also be applied to a wiring board 10. That is, the wiring board 10 includes a conductor layer 15, a first insulating layer 11 disposed on the upper surface of the conductor layer 15, and a first wiring 31, a second wiring 32, a third wiring 33, and a fourth wiring 34 disposed on the first insulating layer 11. The first insulating layer 11 has one or more through holes 16, and a metal member 17 is disposed inside the through holes 16. At least one of the third wiring 33 and the fourth wiring 34 is electrically connected to the conductor layer 15 via the metal member 17 disposed inside the through holes 16. The wiring board 10 can accommodate a first light-emitting device 20A including a first anode 23A1 and a first cathode 23A2, and a second light-emitting device 20B including a second anode 23B1 and a second cathode 23B2. The first wiring 31 can be electrically connected to the first anode 23A1, the second wiring 32 can be electrically connected to the first cathode 23A2 and the second anode 23B1, and the third wiring 33 can be electrically connected to the second cathode 23B2. This configuration can provide a wiring board 10 that has the same effects as the above embodiment.

[0075] Furthermore, although the above embodiment has described light emission control in the light source 100, this is not limiting. For example, in the above embodiment, the conductor layer 15 is connected to ground via the fourth wiring 34. However, the conductor layer 15 may also be connected to a power supply having a predetermined potential via the fourth wiring 34. In this case, the first anode 23A1 and the first cathode 23A2 of the first light-emitting device 20A may be swapped, the second anode 23B1 and the second cathode 23B2 of the second light-emitting device 20B may be swapped, and the Low and High of the first potential V1 and the second potential V2 may be swapped. In this way, either or both of the first light-emitting device 20A and the second light-emitting device 20B may emit light.

[0076] The present disclosure includes the following aspects. (Appendix 1) a wiring board having a conductor layer and a first insulating layer disposed on an upper surface of the conductor layer, the wiring board including a first wiring, a second wiring, a third wiring, and a fourth wiring disposed on the first insulating layer; a light source including a first light emitting device and a second light emitting device disposed on an upper surface of the wiring substrate, the third wiring and the fourth wiring are electrically connected to the conductor layer; the first light emitting device comprises a first anode and a first cathode; the second light emitting device includes a second anode and a second cathode; the first anode is electrically connected to the first wiring; the first cathode and the second anode are electrically connected to the second wiring; The second cathode is electrically connected to the third wiring. (Appendix 2) the first wiring has a pad, 2. The light source according to claim 1, wherein, in a plan view, the pad of the first wiring, the first anode of the first light emitting device, and the second cathode of the second light emitting device are arranged along a first direction. (Appendix 3) the second wiring has a pad, In a plan view, the first wiring and the second wiring are arranged side by side along a second direction perpendicular to the first direction, 3. The light source according to claim 2, wherein a pad of the second wiring, a first cathode of the first light emitting device, and the second anode of the second light emitting device are arranged along a first direction. (Appendix 4) 4. The light source according to claim 1, wherein the wiring substrate further comprises a second insulating layer disposed on a lower surface of the conductor layer. (Appendix 5) the light source further includes a third light emitting device disposed on an upper surface of the wiring substrate; 5. The light source according to claim 1, wherein the first light emitting device, the second light emitting device, and the third light emitting device are arranged along a first direction. (Appendix 6) the light source further includes a third light emitting device and a fourth light emitting device disposed on an upper surface of the wiring substrate; the wiring board further includes a fifth wiring, a sixth wiring, and a seventh wiring arranged on the first insulating layer; the seventh wiring is electrically connected to the conductor layer, the first light emitting device, the second light emitting device, the fourth light emitting device, and the third light emitting device are arranged along a first direction; the third light emitting device includes a third anode and a third cathode; the fourth light emitting device includes a fourth anode and a fourth cathode; the third anode is electrically connected to the fifth wiring, the third cathode and the fourth anode are electrically connected to the sixth wiring; 5. The light source according to claim 1, wherein the fourth cathode is electrically connected to the seventh wiring. (Appendix 7) the first insulating layer has one or more through holes; A metal member is disposed inside the through hole, A light source described in any one of Appendix 1 to 6, wherein the third wiring, the fourth wiring, and the seventh wiring are electrically connected to the conductor layer via the metal member arranged inside the through hole. (Appendix 8) A wiring board having a conductor layer and a first insulating layer disposed on an upper surface of the conductor layer, the wiring board including a first wiring, a second wiring, a third wiring, and a fourth wiring disposed on the first insulating layer, the first insulating layer has one or more through holes; A metal member is disposed inside the through hole, at least one of the third wiring and the fourth wiring is electrically connected to the conductor layer via the metal member disposed inside the through hole; the wiring substrate is capable of arranging a first light emitting device including a first anode and a first cathode, and a second light emitting device including a second anode and a second cathode; the first wiring is electrically connectable to the first anode; the second wiring is electrically connectable to the first cathode and the second anode; the third wiring is electrically connectable to the second cathode;

[0077] The embodiments of the present disclosure have been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. All forms that can be implemented by a person skilled in the art through appropriate design modifications based on the above-described embodiments of the present disclosure also fall within the scope of the present disclosure as long as they include the gist of the present disclosure. In addition, within the scope of the concept of the present disclosure, a person skilled in the art may conceive of various modifications and alterations, and these modifications and alterations also fall within the scope of the present disclosure. [Explanation of symbols]

[0078] 10: wiring board, 11: first insulating layer, 12: second insulating layer, 15: conductor layer, 16: through hole, 17: metal member, 20: light emitting device, 20A: first light emitting device, 20B: second light emitting device, 20C: third light emitting device, 20D: fourth light emitting device, 21: light-transmitting member, 22: light emitting element, 23: electrode, 23A: first electrode, 23A1: first anode, 23A2: first cathode, 23B: second electrode, 23B1: second anode, 23B2: second cathode, 23C: third electrode, 23C1: third anode, 23C2: third cathode, 23D: fourth electrode, 23D1: fourth anode, 23D2: fourth cathode, 30: wiring, 31: first wiring, 31a: pad, 31b: Connecting portion, 31c: terminal, 32: second wiring, 32a: pad, 32b1: first connecting portion, 32b2: second connecting portion, 32c1: first terminal, 32c2: second terminal, 33: third wiring, 33c: terminal, 34: fourth wiring, 34a: pad, 35: fifth wiring, 35a: pad, 35b: connecting portion, 35c: terminal, 36: sixth wiring, 36a: pad, 36b1: first connecting portion, 36b2: second connecting portion, 36c1: first terminal, 36c2: second terminal, 37: seventh wiring, 37c: terminal, 41: first convex portion, 42: second convex portion, 50: covering member, 61: first terminal, 62: second terminal, 70: wire, 100: light source, 150: light source, 200: light source, 210: base substrate

Claims

1. a wiring substrate having a conductor layer and a first insulating layer disposed on an upper surface of the conductor layer, the wiring substrate including a first wiring, a second wiring, a third wiring, and a fourth wiring disposed on the first insulating layer; a light source including a first light emitting device and a second light emitting device disposed on an upper surface of the wiring substrate, the third wiring and the fourth wiring are electrically connected to the conductor layer; the first light emitting device includes a first anode and a first cathode; the second light emitting device includes a second anode and a second cathode; the first anode is electrically connected to the first wiring; the first cathode and the second anode are electrically connected to the second wiring; The second cathode is electrically connected to the third wiring.

2. the first wiring has a pad, The light source according to claim 1 , wherein, in a plan view, the pad of the first wiring, the first anode of the first light-emitting device, and the second cathode of the second light-emitting device are arranged along a first direction.

3. the second wiring has a pad, In a plan view, the first wiring and the second wiring are arranged side by side along a second direction perpendicular to the first direction, The light source according to claim 2 , wherein the pad of the second wiring, the first cathode of the first light emitting device, and the second anode of the second light emitting device are arranged along a first direction.

4. The light source according to claim 1 , wherein the wiring board further comprises a second insulating layer disposed on a lower surface of the conductor layer.

5. the light source further includes a third light-emitting device disposed on the upper surface of the wiring substrate; The light source of claim 1 , wherein the first light emitting device, the second light emitting device, and the third light emitting device are arranged along a first direction.

6. the light source further includes a third light-emitting device and a fourth light-emitting device disposed on an upper surface of the wiring substrate; the wiring board further includes a fifth wiring, a sixth wiring, and a seventh wiring arranged on the first insulating layer; the seventh wiring is electrically connected to the conductor layer, the first light emitting device, the second light emitting device, the fourth light emitting device, and the third light emitting device are arranged along a first direction; the third light emitting device includes a third anode and a third cathode; the fourth light emitting device includes a fourth anode and a fourth cathode; the third anode is electrically connected to the fifth wiring, the third cathode and the fourth anode are electrically connected to the sixth wiring; The light source according to claim 1 , wherein the fourth cathode is electrically connected to the seventh wiring.

7. the first insulating layer has one or more through holes; A metal member is disposed inside the through hole, The light source according to claim 6, wherein the third wiring, the fourth wiring, and the seventh wiring are electrically connected to the conductor layer via the metal member arranged inside the through hole.

8. A wiring board having a conductor layer and a first insulating layer disposed on an upper surface of the conductor layer, the wiring board including a first wiring, a second wiring, a third wiring, and a fourth wiring disposed on the first insulating layer, the first insulating layer has one or more through holes; A metal member is disposed inside the through hole, At least one of the third wiring and the fourth wiring is electrically connected to the conductor layer via the metal member disposed inside the through hole, the wiring substrate is capable of arranging a first light emitting device including a first anode and a first cathode, and a second light emitting device including a second anode and a second cathode; the first wiring is electrically connectable to the first anode; the second wiring is electrically connectable to the first cathode and the second anode; The third wiring is electrically connectable to the second cathode.

Images