Circuit board and semiconductor light emitting device

Abstract

To provide a circuit board in which a bonding member is prevented from reaching a light-emitting element when a window member (lid) is bonded, and to provide a highly reliable semiconductor light-emitting device in which the light-emitting element is mounted on the circuit board and airtight sealing is surely performed.SOLUTION: The semiconductor device includes a substrate, at least one electrode wiring provided on the substrate, and a surrounding wiring provided on the substrate and surrounding the at least one electrode wiring. The surrounding wire includes an annular main body portion that is an annular wire, and a pair of bridge wires that are strip-shaped wires extending from one branch point to the other branch point of the annular main body portion and facing each other inside the annular main body portion, and at least one electrode wire is provided in an inner region of the annular main body portion and the pair of bridge wires.SELECTED DRAWING: FIG. 2A

Description

[Technical Field]

[0001] The present invention relates to a circuit board and a semiconductor light-emitting device, and more particularly to a circuit board and a semiconductor light-emitting device in which a light-emitting element mounted on the circuit board is hermetically sealed. [Background technology]

[0002] BACKGROUND ART Semiconductor light emitting devices are known in which a semiconductor light emitting element such as a light emitting diode (LED) or a laser diode (LD) is housed in a package and hermetically sealed with a cover glass.

[0003] For example, Patent Document 1 discloses an optical semiconductor device including a package substrate, a window member, an optical semiconductor element 20 to be housed therein, and a metal bonding portion that seals the gap between the package substrate and the window member. It is disclosed that the optical semiconductor device has a separation surface that stops the flow of metal bonding material along the light reflecting surface, thereby improving reliability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-037583 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional semiconductor light emitting devices, when the circuit board and the window member are joined, the joining member may reach the light emitting element, causing problems such as a decrease in light output or a short circuit in the light emitting element.

[0006] The present invention has been made in consideration of the above points, and aims to provide a circuit board in which the joining member is prevented from reaching the light-emitting element when the window member (lid) is joined, and a highly reliable semiconductor light-emitting device in which the light-emitting element is mounted on the circuit board and is securely hermetically sealed. [Means for solving the problem]

[0007] A circuit board according to one embodiment of the present invention comprises: A substrate; At least one electrode wiring provided on the substrate; a surrounding wiring provided on the substrate and surrounding the at least one electrode wiring; the surrounding wiring has an annular main body portion which is an annular wiring, and a pair of bridge wirings which are band-shaped wirings inside the annular main body portion and which face each other, each bridge wiring being a pair of opposing band-shaped wirings extending from one branch point of the annular main body portion to another branch point; The at least one electrode wiring is provided in an inner region of the annular main body and the pair of bridge wirings.

[0008] A semiconductor light emitting device according to another embodiment of the present invention includes: The circuit board described above; a semiconductor light emitting element mounted across the bridge wiring and the electrode wiring; The semiconductor light emitting element includes a lid that is joined to the annular main body with a joining member and that hermetically seals the circuit board while enclosing the semiconductor light emitting element. [Brief explanation of the drawings]

[0009] [Figure 1A] FIG. 1 is a top view schematically showing a light emitting device according to a first embodiment. [Figure 1B] 2 is a side view of the light emitting device as viewed in a direction perpendicular to the line AA shown in FIG. [Figure 1C] FIG. 2 is a cross-sectional view schematically showing a cross section of the light emitting device taken along line AA shown in FIG. [Figure 1D] FIG. 2 is a bottom view of the light emitting device. [Figure 2A] FIG. 2 is a plan view showing circuit wiring, which is board wiring formed on a base of a circuit board. [Figure 2B] FIG. 2 is a plan view showing a detailed configuration of the annular wiring; [Figure 3A] 1 is a plan view showing an element mounting substrate on which four light emitting elements 20 and a protective element are mounted on circuit wiring. [Figure 3B] FIG. 3B is a cross-sectional view showing a cross section taken along line BB shown in FIG. 3A. [Figure 4A] 10 is a plan view showing a device mounting substrate in which a bonding member is provided on an annular main body portion of an annular wiring; FIG. [Figure 4B] 4B is a cross-sectional view schematically showing a cross section of the element mounting board taken along line AA shown in FIG. 4A. FIG. [Figure 4C] FIG. 4 is a cross-sectional view showing the bonding between the element mounting substrate and the cap. [Figure 5A] FIG. 1 is a plan view schematically showing a light emitting device according to a first embodiment. [Figure 5B] An X-ray image of a light-emitting device showing excess bonding material that has flowed out. [Figure 6A] FIG. 10 is a plan view schematically showing the inside of a light emitting device having annular wiring as a comparative example CX1. [Figure 6B] FIG. 6B is a cross-sectional view schematically showing a cross section of the light emitting device of the comparative example (CX1) taken along the line WW shown in FIG. 6A. [Figure 7] FIG. 1 is a plan view showing a circuit board according to a first modified example of the first embodiment. [Figure 8] FIG. 10 is a plan view showing a circuit board according to a second modification of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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 are designated by the same reference numerals.

[0011] [First embodiment] (1) Structure of semiconductor light-emitting device Fig. 1A is a top view schematically illustrating a light emitting device 10, which is a semiconductor light emitting device according to a first embodiment of the present invention. Fig. 1B is a side view of the light emitting device 10 as viewed from a direction perpendicular to line AA shown in Fig. 1, Fig. 1C is a cross-sectional view schematically illustrating the cross section of the light emitting device 10 taken along line AA shown in Fig. 1, and Fig. 1D is a bottom view of the light emitting device 10.

[0012] The light emitting device 10 has a circuit board 11 which is a mounting substrate, and a cap 30 (lid) which is a window member, and the circuit board 11 and the cap 30 are joined by a joining member 25. The circuit board 11 has a base 12, circuit wiring 13 formed on the base 12, and a mounting electrode 22 formed on the bottom surface of the base 12.

[0013] The cap 30 has a flange 30F, and the flange 30F is joined to the circuit wiring 13 by a joining member 25, sealing the cap 30 and the circuit board 11. At least one light-emitting element 20 (semiconductor light-emitting element) and a protective element 27 are accommodated in a sealed space (accommodation space) defined by the cap 30 and the circuit board 11. The light-emitting element 20 and the protective element 27 are mounted on the circuit wiring 13.

[0014] The light emitting element 20 is, for example, a light emitting diode (LED) that emits light in the deep ultraviolet band, but is not limited to this. Also, for example, a wavelength converter such as a phosphor may be provided on the light emitting diode. Alternatively, the light emitting element 20 may be a semiconductor laser (LD). Also, light emitting elements of different emission colors or different types may be provided.

[0015] Furthermore, although the case where the light emitting element 20 and the protective element 27 are provided will be described, the present invention is not limited to this. For example, the protective element 27 may not be provided.

[0016] 2A is a plan view showing circuit wiring 13, which is substrate wiring formed on base 12 of circuit board 11. Circuit wiring 13 has annular wiring 15, anode wiring 16 (first wiring), cathode wiring 17 (second wiring), and intermediate wirings 18A and 18B.

[0017] The base 12 is made of, for example, aluminum nitride (AlN), but is not limited to this. For example, insulating ceramics such as alumina (Al2O3) can be used. The annular wiring 15, the anode wiring 16, the cathode wiring 17, and the intermediate wiring 18A, 18B can be made of, for example, copper (Cu) plated with nickel / gold (Ni / Au), but are not limited to this. The circuit wiring 13 can be formed by patterning a circuit wiring metal layer using lithography or the like.

[0018] 2B is a plan view showing a detailed configuration of the annular wiring 15. The annular wiring 15 is a wiring (encircling wiring) that surrounds at least one electrode wiring, and at least one light-emitting element is mounted within the surrounded inner region 15K (mounting region).

[0019] More specifically, the annular wiring 15 includes an annular main body 15M having a closed ring shape, a pair of bridge wirings 15B (first and second bridge wirings) that are strip-shaped wirings, an element mounting portion 15P (element mounting wiring), and storage portions 15R and 15Q. In this embodiment, the annular main body 15M has a rectangular ring shape with a constant width. The annular main body 15M functions as a sealing bonding metal layer with the cap 30.

[0020] The corners of the annular main body 15M are rounded. In this specification, the term "rectangular ring" will be used to refer to any ring having rounded corners.

[0021] The bridge wiring 15B is a wiring that extends linearly from a branch point on one side of the annular main body 15M to a branch point on the other side opposite the first side. Therefore, a gap 15G is formed between the bridge wiring 15B and the annular main body 15M. A pair of parallel bridge wirings 15B facing each other is provided in the annular wiring 15. Inside the pair of bridge wirings 15B, in an inner region 15K surrounded by the pair of bridge wirings 15B and two sides of the annular main body 15M (sides perpendicular to the pair of bridge wirings 15B), the anode wiring 16 (first wiring), the cathode wiring 17 (second wiring), and the intermediate wirings 18A and 18B, which are electrode wirings, are arranged.

[0022] Depending on the number and connection form of the light-emitting elements 20 mounted and connected on the circuit wiring 13, any of the anode wiring 16, the cathode wiring 17, and the intermediate wiring 18A, 18B may not be provided, or additional anode wiring 16, cathode wiring 17, and any of the intermediate wiring 18A, 18B may be provided.

[0023] The bridge wiring 15B has a storage portion 15R at a branch portion BR (an end portion of the bridge wiring 15B) with the annular main body portion 15M. The storage portion 15R is formed as a widened portion that is wide in width (perpendicular to the extension direction) of the bridge wiring 15B, and prevents the joining material from flowing toward the center of the bridge wiring 15B when the annular main body portion 15M and the flange 30F of the cap 30 are joined. In the annular wiring 15 of this embodiment, the storage portion 15R (widened portion) has a width that decreases stepwise in the extension direction of the bridge wiring 15B, but the width may also decrease smoothly.

[0024] The reservoirs 15R are provided at both the annular main body 15M and the branch portion BR of each bridge wiring 15B, and prevent the inflow of the bonding material from the annular main body 15M. In addition, between the pair of bridge wirings 15B, the annular main body 15M perpendicular to the pair of bridge wirings 15B is provided with reservoirs 15Q (i.e., widened portions of the annular main body 15M) protruding from the annular main body 15M toward the inner region 15K, and prevent excess bonding material from flowing down the annular main body 15M into the bridge wiring 15B.

[0025] The element mounting portion 15P is provided midway between both branch portions BR of the bridge wiring 15B, and prevents the flowing out bonding material from reaching the light emitting element 20. In other words, the element mounting portion 15P is provided at a position where the bonding material flowing in from the end of the bridge wiring 15B cannot reach it.

[0026] As shown in Figures 1D and 2A, via electrodes 19 (penetrating electrodes) are provided to electrically connect the mounting electrode 22A (anode) and the mounting electrode 22B (cathode) formed on the bottom surface of the base 12 to the anode wiring 16 and the cathode wiring 17, respectively.

[0027] FIG. 3A is a plan view showing an element mounting board 11A in which four light-emitting elements 20(1), 20(2), 20(3), and 20(4) and a protective element 27 are mounted on circuit wiring 13 of a circuit board 11. To help understand the electrical connection state, the polarities (+) and (-) of the four light-emitting elements 20(1) to 20(4) are indicated, respectively. FIG. 3B is a cross-sectional view showing a cross section taken along line BB shown in FIG. 3A. When the light-emitting elements 20(1) to 20(4) are not particularly distinguished from one another, they will be described as light-emitting elements 20.

[0028] The light emitting element 20(1) is joined by a joining member 23 across the anode wiring 16 and the intermediate wiring 18B, and the p-electrode and n-electrode (not shown) of the light emitting element 20(1) are connected to the anode wiring 16 and the intermediate wiring 18B, respectively.

[0029] The light-emitting element 20(2) is joined by a joining member 23 across the intermediate wiring 18B and the element mounting portion 15P of one of the bridge wirings 15B (first bridge wiring), and the p-electrode and n-electrode (not shown) of the light-emitting element 20(2) are connected to the intermediate wiring 18B and the element mounting portion 15P, respectively.

[0030] The light-emitting element 20(3) is joined by a joining member 23 across the element mounting portion 15P and intermediate wiring 18A of the other bridge wiring 15B (second bridge wiring), and the p-electrode and n-electrode (not shown) of the light-emitting element 20(3) are connected to the element mounting portion 15P and intermediate wiring 18A, respectively.

[0031] Here, the other bridge wiring 15B is electrically connected to the one bridge wiring 15B, and therefore the p-electrode of the light-emitting element 20(3) is electrically connected to the n-electrode of the light-emitting element 20(2).

[0032] The light emitting element 20(4) is joined across the intermediate wiring 18A and the cathode wiring 17 by a joining member 23, and the p-electrode and n-electrode (not shown) of the light emitting element 20(4) are connected to the intermediate wiring 18A and the cathode wiring 17, respectively.

[0033] That is, light emitting elements 20(1), 20(2), 20(3), and 20(4) are connected in series in this order. Therefore, by applying a voltage between anode wiring 16 and cathode wiring 17 via mounting electrodes 22A and 22B and via electrode 19, a drive current flows in the direction of light emitting elements 20(1) to 20(4).

[0034] Furthermore, a protection element 27, such as a Zener diode, is mounted on the anode wiring 16 and the cathode wiring 17, and is connected between the anode wiring 16 and the cathode wiring 17 in parallel with the light emitting elements 20(1) to 20(4) connected in series.

[0035] Figure 4A is a plan view showing an element mounting substrate 11A in which a bonding member 25 is provided on an annular main body portion 15M of an annular wiring 15, and Figure 4B is a cross-sectional view schematically showing a cross section of the element mounting substrate 11A taken along line AA shown in Figure 4A.

[0036] A bonding member 25 is disposed around the entire circumference of the annular main body 15M of the annular wiring 15. The bonding member 25 may be, for example, a fluxless gold-tin (Au—Sn) ribbon, but is not limited to this. For example, an Au—Sn alloy layer may be provided in advance by vapor deposition or the like on the metal layer 34 of the flange 30F or on the annular main body 15M.

[0037] 4C is a cross-sectional view showing the bonding of the element mounting substrate 11A and the cap 30. The annular main body 15M and the flange 30F are bonded together by heating and pressing (indicated by the arrow in the figure) using the bonding member 25. This completes the light emitting device 10 (FIGS. 1A to 1D) that includes the light emitting element 20 and is hermetically sealed by the element mounting substrate 11A and the cap 30.

[0038] The cap 30 can be made of glass, such as quartz glass or borosilicate glass, that transmits the light emitted from the light-emitting element 20. When the flange 30F is made of glass, a metal layer 34 is provided that is fixed to the bottom surface (joint surface) of the flange 30F. The metal layer 34 is, for example, a laminated metal layer in which chromium (Cr), Ni, and Au are laminated in this order. Hereinafter, this laminated metal layer will be referred to as Cr / Ni / Au.

[0039] (2) Storage of joining materials Fig. 5A is a plan view schematically illustrating the light emitting device 10 of this embodiment. More specifically, it shows the interior of the light emitting device 10 with excess bonding material SD flowing out when the cap 30 is bonded. Fig. 5B is an X-ray image of the light emitting device 10, showing the excess bonding material SD that has flowed out.

[0040] Fig. 6A is a plan view schematically showing the inside of a light emitting device 110 having annular wiring as a comparative example CX1. Fig. 6B is a cross-sectional view schematically showing a cross section of the light emitting device 110 taken along line WW shown in Fig. 6A.

[0041] 6A, the light emitting device 110 of Comparative Example CX1 differs from the light emitting device 10 of this embodiment in that it does not have a bridge wiring 15B. More specifically, the light emitting device 110 of Comparative Example CX1 has an annular wiring 115 consisting of an annular main body portion 115M similar to the annular main body portion 15M of the light emitting device 10, and two element mounting portions 115P protruding from the annular main body portion 115M toward the intermediate wirings 18A and 18B, respectively.

[0042] In the light emitting device 110, the p-electrode and n-electrode (not shown) of the light emitting element 20(2) are joined and electrically connected to the intermediate wiring 18B and the element mounting portion 115P, respectively. Also, the p-electrode and n-electrode (not shown) of the light emitting element 20(3) are joined and electrically connected to the element mounting portion 115P and the intermediate wiring 18B, respectively.

[0043] As shown in Figures 6A and 6B, the cap 30 is joined to the annular main body portion 115M by the joining member 25, but when the cap 30 and the annular main body portion 115M are joined, excess joining member SD flows down the element mounting portion 115P and reaches the light emitting elements 20(2), 20(3), causing problems such as a short circuit in the element and a decrease in light output.

[0044] On the other hand, as shown in Fig. 5A, in the light emitting device 10 of this embodiment, excess bonding material SD that has flowed out from the annular main body 15M is stopped by the reservoir 15R (see Fig. 2B) of the bridge wiring 15B, and is prevented from reaching the light emitting element 20. As shown in Fig. 5B, it can be seen that the excess bonding material SD that has flowed out is stored in the reservoir 15R (black or dark gray portion) and is stopped.

[0045] Therefore, defects such as short circuits in the elements and reduced optical output caused by excess joining material can be prevented, and a highly reliable semiconductor light emitting device with a secure hermetic seal can be provided.

[0046] Furthermore, excess bonding material SD is also stored in storage portion 15Q protruding from annular main body portion 15M, which reduces the inflow of excess bonding material SD into bridge wiring 15B and inner region 15K (FIG. 2B), thereby providing a highly reliable semiconductor light emitting device.

[0047] Furthermore, in the light emitting device 10 of this embodiment, even if excess bonding material flows out, it is prevented from reaching the light emitting element 20, so a sufficient amount of bonding material can be used and reliable airtight sealing can be achieved, thereby providing a highly reliable semiconductor light emitting device. (3) Variations

[0048] (Variation 1) FIG. 7 is a plan view showing a circuit board 51 according to Modification 1 of the first embodiment. It differs from the circuit board 11 of the light-emitting device 10 of the first embodiment in that a reservoir 15R (widened portion) is not provided at the branch portion BR of the bridge wiring 15B, where the bridge wiring 15B connects to the annular main body portion 15M. Furthermore, an element mounting portion 15P protruding inward from the bridge wiring 15B1 is provided midway between the two branches BR of one bridge wiring 15B1, while the other bridge wiring 15B2 does not have an element mounting portion 15P. The widths of the bridge wirings 15B1 and 15B2 are the same as the width of the reservoir 15R. That is, the widths of the bridge wirings 15B1 and 15B2 provide a sufficient reservoir area to prevent excess bonding material SD from reaching the light-emitting element 20, even if it flows in.

[0049] Even if the reservoir 15R is not provided, the bridge wirings 15B1 and 15B2 prevent the overflowing excess bonding material from reaching the light emitting element 20, thereby preventing problems such as element short-circuiting and a decrease in light output.

[0050] Furthermore, although the bridge wiring 15B2 does not have an element mounting portion 15P, even when the light-emitting element 20 is mounted on the intermediate wiring 18B and the bridge wiring 15B2, the bridge wiring 15B2 prevents excess bonding material from flowing out and reaching the light-emitting element 20, thereby preventing defects such as element short-circuiting and a decrease in light output.

[0051] Therefore, defects such as short circuits in the element and a decrease in light output caused by excess joining material are prevented, and a highly reliable semiconductor light emitting device with a secure hermetic seal is provided.

[0052] (Variation 2) 8 is a plan view showing a circuit board 61 which is a modified example 2 of the first embodiment. In the circuit board 61, a storage portion 15R (widened portion) is provided along the inner periphery of an annular main body portion 15M, and a pair of parallel strip-shaped gap portions 15G are provided within the storage portion 15R.

[0053] In other words, the extending direction of the strip-shaped gap 15G is the extending direction of the bridge wiring 15B, and the light emitting element 20 is placed and mounted on the bridge wiring 15B or the element mounting portion 15P protruding inward from the bridge wiring 15B.

[0054] In FIG. 8, the boundary BD between the annular main body portion 15M and the storage portion 15R is indicated by a dashed line. The annular main body portion 15M has a constant width and is a sealing joint area with the cap 30.

[0055] In the circuit board 61 of the second modification, the area of ​​the reservoir 15R is large, and even if a large amount of excess bonding material flows out, the bonding material can be prevented from reaching the light emitting element 20.

[0056] As described above in detail, according to the present disclosure, when a window member is bonded to a circuit board, the bonding member is prevented from reaching the light emitting element, and a highly reliable semiconductor light emitting device with a secure hermetic seal can be provided. Note that the present invention is not limited to the content of the above-described embodiment, and can be applied by appropriate modifications and combinations within the scope of the present disclosure.

[0057] For example, although the annular main body to be sealed and joined has a rectangular ring shape in the above description, the shape is not limited to this and may have a circular ring shape, an oval ring shape, a polygonal ring shape, or the like.

[0058] In addition, although the example has been described in which a pair of bridge wirings are provided, it is sufficient that at least one bridge wiring is provided. Furthermore, although the circuit board and semiconductor light-emitting device have been described in which four light-emitting elements in a series-connected configuration are mounted, it is sufficient that at least one light-emitting element is mounted. Furthermore, when multiple light-emitting elements are mounted, they are not limited to being connected in series, but may be connected in series and / or in parallel. Furthermore, it is sufficient that electrode wiring and intermediate electrodes are provided according to the connection and mounting configuration of the multiple light-emitting elements. [Explanation of symbols]

[0059] 10: Light emitting device 11: Circuit board 11A: Element mounting board 12: Base 13:Circuit wiring 15: Ring wiring 15B, 15B1, 15B2: Bridge wiring 15G: Gap 15K: Inner area 15M: Annular body 15P: Element mounting part 15Q, 15R: Reservoir section 16: Anode wiring 17: Cathode wiring 18A: Intermediate wiring 18B: Intermediate wiring 19: Via electrode 20: Light emitting element 22, 22A, 22B: Mounting electrodes 23, 25: Joint material 27: Protective element 30: Cap (lid) 30F: Flange 34: Metal layer 51, 61: Circuit board 110: Light emitting device of comparative example 115: Circular wiring of the comparative example 115M: Annular body part of comparative example 115P: Element mounting part of comparative example SD: Joint material

Claims

1. A substrate; At least one electrode wiring provided on the substrate; a surrounding wiring provided on the substrate and surrounding the at least one electrode wiring; the surrounding wiring includes an annular main body portion that is an annular wiring, and a pair of bridge wirings that are opposed to each other and are strip-shaped wirings that extend from one branch point of the annular main body portion to another branch point inside the annular main body portion, the at least one electrode wiring is provided in an inner region of the annular main body portion and the pair of bridge wirings; Circuit board.

2. The circuit board according to claim 1 , wherein the bridge wiring has a widened portion at a branch point from the annular main body portion.

3. The circuit board according to claim 1 , wherein the bridge wiring has an element mounting portion that protrudes from the bridge wiring toward the inner region.

4. the annular body portion has a rectangular annular shape; the pair of bridge wirings are provided on the inner sides of a pair of opposing sides of the annular main body portion, parallel to the pair of sides and spaced apart from each other, The circuit board according to claim 1 , wherein both ends of the bridge wiring are connected to another pair of sides of the annular main body that are perpendicular to the pair of bridge wirings.

5. A circuit board according to any one of claims 1 to 4; a semiconductor light emitting element mounted across the bridge wiring and the electrode wiring; a lid joined to the annular main body by a joining member, the lid enclosing the semiconductor light emitting element and hermetically sealing the circuit board;

6. the bridge wiring has an element mounting portion protruding from the bridge wiring toward the inner region, The semiconductor light emitting device according to claim 5 , wherein the semiconductor light emitting element is mounted across the element mounting portion and the electrode wiring.

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