Light emitting device

Abstract

Provided is a light-emitting device capable of achieving both high heat dissipation performance and suppression of warpage. The light-emitting device includes: a first substrate; a second substrate that is disposed on the first substrate, has a shape that is long in a first direction in plan view, and has a thermal expansion coefficient different from that of the first substrate; a plurality of light emitting elements disposed on the second substrate; and a bonding member that bonds the second substrate to the first substrate. The joining member has: a first portion, the length of the first portion in the first direction being equal to or less than the length of the first portion in a second direction orthogonal to the first direction; and second portions disposed on both sides of the first portion in the first direction, the Young's modulus of the second portions being lower than the Young's modulus of the first portion, and the thermal conductivity of the second portions being lower than the thermal conductivity of the first portion.

Description

Technical Field

[0001] The present disclosure relates to a light-emitting device. Background Art

[0002] A light-emitting device has been developed in which a circuit board is arranged on a mounting board and a plurality of light-emitting elements are arranged on the circuit board. When the plurality of light-emitting elements emit light with high brightness, a large amount of heat is generated, and thus high heat dissipation is required for the light-emitting device. On the other hand, generally, the thermal expansion rates between the mounting board and the circuit board are different, and thus warping may occur in the light-emitting device due to the heat treatment during the manufacture of the light-emitting device. When warping occurs, the optical accuracy of the light-emitting device decreases.

[0003] [Prior Art Documents]

[0004] [Patent Documents]

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-027116 Summary of the Invention

[0006] [Problems to be Solved by the Invention]

[0007] The embodiment has been completed in view of the above problems, and an object thereof is to provide a light-emitting device capable of achieving both high heat dissipation and suppression of warping.

[0008] [Solutions to the Problems]

[0009] The light-emitting device according to the embodiment includes: a first substrate; a second substrate arranged on the first substrate, having a shape that is long in a first direction in a plan view, and having a different thermal expansion rate from that of the first substrate; a plurality of light-emitting elements arranged on the second substrate; and a bonding member that bonds the second substrate to the first substrate. The bonding member has: a first portion, the length of the first portion in the first direction being equal to or less than the length of the first portion in a second direction orthogonal to the first direction; and a second portion arranged on both sides of the first portion in the first direction, the Young's modulus of the second portion being lower than that of the first portion, and the thermal conductivity of the second portion being lower than that of the first portion.

[0010] [Advantages of the Invention]

[0011] According to the embodiment, a light-emitting device capable of achieving both high heat dissipation and suppression of warping can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a plan view showing a light-emitting device according to a first embodiment.

[0013] Figure 2 is a partial enlarged top view of region II showing Figure 1 .

[0014] Figure 3 is a cross-sectional view taken along line III-III based on Figure 1 shown.

[0015] Figure 4 is a top view showing the bonding member of the light-emitting device according to the first embodiment.

[0016] Figure 5 is a top view showing the process of disposing the sintered silver paste and the silver paste on the first substrate in the first embodiment.

[0017] Figure 6 is a schematic cross-sectional view showing the occurrence of warpage in the light-emitting device according to the comparative example.

[0018] Figure 7 is a schematic cross-sectional view showing the occurrence of warpage in the light-emitting device according to the first embodiment.

[0019] Figure 8 is a top view showing the bonding member of the light-emitting device according to the second embodiment.

[0020] Figure 9 is a top view showing the process of disposing the sintered silver paste and the silver paste on the first substrate in the second embodiment.

[0021] Figure 10 is a cross-sectional view showing the light-emitting device according to the third embodiment.

[0022] Figure 11 is a top view showing the bonding member of the light-emitting device according to the third embodiment.

[0023] Figure 12 is a top view showing the process of disposing the sintered silver paste and the silver paste on the first substrate in the third embodiment.

[0024] Figure 13 is a top view showing the bonding member of the light-emitting device according to the first modification of the third embodiment.

[0025] Figure 14 is a top view showing the bonding member of the light-emitting device according to the second modification of the third embodiment.

[0026] Figure 15 is a top view showing the bonding member of the light-emitting device according to the third modification of the third embodiment.

[0027] Figure 16It is a cross-sectional view showing a light-emitting device according to the fourth embodiment.

[0028] Figure 17 It is a top view showing a joining member of a light-emitting device according to the fourth embodiment.

[0029] Figure 18 It is a top view showing a process of disposing a sintered silver paste and a silver paste on a first substrate in the fourth embodiment.

[0030] Figure 19 It is a cross-sectional view showing a light-emitting device according to a modified example of the fourth embodiment.

[0031] Figure 20 It is a top view showing a process of disposing a sintered silver paste and a silver paste on a first substrate in a modified example of the fourth embodiment.

[0032] Figure 21 It is a cross-sectional view showing a light-emitting device according to the fifth embodiment.

[0033] Figure 22 It is a cross-sectional view showing a light-emitting device according to the sixth embodiment.

[0034] Figure 23A It is a top view showing a joining member of a light-emitting device according to the sixth embodiment.

[0035] Figure 23B It is a bottom view showing a second substrate of a light-emitting device according to the sixth embodiment.

[0036] Figure 24 It is a partially enlarged cross-sectional view showing a light-emitting device according to the seventh embodiment.

[0037] Figure 25A It is a top view showing the arrangement of a sintered silver paste and a silver paste of a sample according to Comparative Example 1 in a test example.

[0038] Figure 25B It is a top view showing the arrangement of a sintered silver paste and a silver paste of a sample according to Example 1 in a test example.

[0039] Figure 25C It is a top view showing the arrangement of a sintered silver paste and a silver paste of a sample according to Example 2 in a test example.

[0040] Figure 25D It is a top view showing the arrangement of a sintered silver paste and a silver paste of a sample according to Example 3 in a test example.

[0041] Figure 26A It is a top view showing a joining member of a sample according to Comparative Example 1 in a test example.

[0042] Figure 26B It is a top view of the bonding member of the sample related to Example 1 in the test example.

[0043] Figure 26C It is a top view of the bonding member of the sample related to Example 2 in the test example.

[0044] Figure 26D It is a top view of the bonding member of the sample related to Example 3 in the test example.

[0045] Figure 27 It is a graph showing the warpage amounts of the respective samples in the test example, with the sample taken as the horizontal axis and the warpage amount taken as the vertical axis.

[0046]

Explanation of Reference Numerals

[0047] 1, 2, 3, 3a, 3b, 3c, 4, 4a, 5, 6, 7, light-emitting device

[0048] 10, first substrate

[0049] 11, wiring layer

[0050] 12, insulating layer

[0051] 14, convex portion

[0052] 15, groove

[0053] 16, concave portion

[0054] 20, second substrate

[0055] 21, metal layer

[0056] 22, semiconductor portion

[0057] 30, light-emitting element

[0058] 31, resin layer

[0059] 32, LED array

[0060] 40, bonding member

[0061] 41, first part

[0062] 41a, sintered silver paste

[0063] 41b, first region

[0064] 42, second part

[0065] 42a, silver paste

[0066] 42b, second region

[0067] 43. Boundary

[0068] 44, 44a, 44b, 44c, Partition member

[0069] 60. Structure

[0070] 61. Phosphor layer

[0071] 62. Conductive wire

[0072] 63. Resin member

[0073] 101. Light-emitting device

[0074] 140. Joining member

[0075] 160. Structure

[0076] L20x. Length of the second substrate 20 in the first direction X

[0077] L20y. Length of the second substrate 20 in the second direction Y

[0078] L41x. Length of the first part 41 in the first direction X

[0079] L41y. Length of the first part 41 in the second direction Y

[0080] S0, S1, S2, S3, Samples

[0081] X. First direction

[0082] Y. Second direction

[0083] Z. Third direction. Detailed implementation mode

[0084] <First implementation mode>

[0085] Figure 1 It is a top view showing the light-emitting device according to this implementation mode.

[0086] Figure 2 It is showing Figure 1 A partial enlarged top view of the area II of.

[0087] Figure 3 It is based on Figure 1 The cross-sectional view taken along the line III-III shown.

[0088] Figure 4 It is a top view showing the joining member of the light-emitting device according to this implementation mode.

[0089] It should be noted that the figures are schematic diagrams, appropriately emphasized and simplified. Additionally, the aspect ratios and positional relationships of the respective constituent elements may not be strictly the same between the figures. The same applies to the other figures described later.

[0090] First, the structure of the light-emitting device 1 according to the present embodiment will be outlined.

[0091] As Figures 1 - 4 shown, the light-emitting device 1 includes a first substrate 10, a second substrate 20, a plurality of light-emitting elements 30, and a bonding member 40. The second substrate 20 is disposed on the first substrate. The coefficient of thermal expansion of the second substrate 20 is different from that of the first substrate 10. The plurality of light-emitting elements 30 are disposed on the second substrate. The bonding member 40 has one first portion 41 and two second portions 42. The Young's modulus of the second portion 42 is lower than that of the first portion 41. Additionally, the thermal conductivity of the first portion 41 is higher than that of the second portion 42. It should be noted that in Figure 4 , the first substrate 10 is shown by a solid line and the second substrate 20 is shown by a dashed line.

[0092] Hereinafter, in the present specification, for ease of explanation, an XYZ orthogonal coordinate system is adopted. The long side direction of the second substrate 20 is set as the "first direction X", the direction from the first substrate 10 toward the second substrate 20 is set as the "third direction Z", and the direction orthogonal to the first direction X and the third direction Z is set as the "second direction Y". The third direction Z, that is, the direction from the first substrate 10 toward the second substrate 20, is also referred to as "up", and the opposite direction is also referred to as "down", but this expression is also for convenience and has no relation to the direction of gravity. Additionally, observing in the third direction Z is referred to as "top view". The top view also includes the case where constituent elements that are actually blocked by other constituent elements and cannot be seen when observing the light-emitting device 1 in the third direction Z are assumed to be visible and shown.

[0093] As Figure 4 shown, the second substrate 20 has a shape that is long in the first direction X. The length L20x of the second substrate 20 in the first direction X is longer than the length L20y of the second substrate 20 in the second direction Y. That is, L20x > L20y. The second portions 42 of the bonding member 40 are disposed on both sides of the first portion 41 in the first direction X. The length L41x of the first portion 41 of the bonding member 40 in the first direction X is less than or equal to the length L41y of the first portion 41 in the second direction Y. That is, L41x ≤ L41y.

[0094] Next, the structure of the light-emitting device 1 will be described in detail.

[0095] The first substrate 10 includes, for example, a metal, such as copper (Cu). The first substrate 10 is, for example, a copper core substrate. More specifically, asFigure 3 As shown, a plurality of wiring layers 11 and a plurality of insulating layers 12 are stacked in the first substrate 10. Wires made of copper are arranged in the wiring layer 11. Vias made of copper are arranged in the insulating layer 12. Therefore, one of the main components of the first substrate 10 is copper. The thickness of the first substrate 10, that is, the length of the first substrate 10 in the third direction Z, is, for example, 500 μm.

[0096] The second substrate 20 is, for example, a circuit board. The second substrate 20 contains, for example, a semiconductor, such as silicon (Si). More specifically, the second substrate 20 is a semiconductor integrated circuit board, for example, an ASIC (Application Specific Integrated Circuit) board. The main component of the second substrate 20 is silicon. Therefore, the thermal expansion rate of the second substrate 20 is smaller than that of the first substrate 10. The shape of the second substrate 20 is a rectangular plate shape with the first direction X as the long side direction, the second direction Y as the short side direction, and the third direction Z as the thickness direction. A metal layer 21 is provided on the lower surface side of the second substrate 20. The second substrate 20 has a semiconductor portion 22 and a metal layer 21.

[0097] The light-emitting element 30 is, for example, an LED (Light Emitting Diode). As Figure 2 and Figure 3 shown, in the light-emitting device 1, a plurality of light-emitting elements 30 are arranged in a matrix shape, for example, along the XY plane. A resin layer 31 is arranged between the light-emitting elements 30. The LED array 32 is composed of a plurality of light-emitting elements 30 and the resin layer 31.

[0098] As Figure 3 and Figure 4 shown, the bonding member 40 is arranged substantially entirely on the lower surface of the second substrate 20. Therefore, the shape of the bonding member 40 is a rectangular plate shape with the first direction X as the long side direction, the second direction Y as the short side direction, and the third direction Z as the thickness direction. The bonding member 40 is in contact with the upper surface of the first substrate 10 and the lower surface of the metal layer 21 of the second substrate 20.

[0099] The first portion 41 of the bonding member 40 contains sintered silver. In the sintered silver, a plurality of silver particles are sintered together. Therefore, the main component of the first portion 41 is silver (Ag). The second portion 42 of the bonding member 40 contains cured silver paste. Resin is arranged in the cured silver paste. For example, silver particles are arranged in a base material made of silicone. Therefore, the main components of the second portion 42 are resin and silver.

[0100] The light-emitting device 1 may also include a phosphor layer 61, a plurality of wires 62, and a resin member 63. The phosphor layer 61 is disposed on the LED array 32. In the phosphor layer 61, phosphors (not shown) are disposed in a base material made of resin. It should be noted that Figure 2 the phosphor layer 61 is omitted.

[0101] The wire 62 connects a terminal (not shown) of the first substrate 10 and a terminal (not shown) of the second substrate 20. The resin member 63 is disposed on an area around an area of the first substrate 10 where the second substrate 20 is mounted and on an outer peripheral portion of the second substrate 20, and covers the wire 62. In a plan view, the shape of the resin member 63 is frame-shaped.

[0102] Next, a method for manufacturing the light-emitting device according to the present embodiment will be described.

[0103] Figure 5 It is a plan view showing a process of disposing a sintered silver paste and a silver paste on a first substrate in the present embodiment.

[0104] In Figure 5 , an area where the first part 41 of the bonding member 40 is to be formed is shown by a two-dot chain line as a "first area 41b", and an area where the second part 42 is to be formed is shown by a two-dot chain line as a "second area 42b".

[0105] First, the first substrate 10 is prepared. In addition, a structure in which a plurality of light-emitting elements 30 are disposed on the second substrate 20 to form an LED array 32 is prepared.

[0106] Next, as Figure 5 shown, a sintered silver paste 41a is disposed in the first area 41b on the first substrate 10. For example, the sintered silver paste 41a is disposed in a single linear shape extending along the second direction Y. The sintered silver paste 41a contains silver particles and a solvent as main materials.

[0107] In addition, a silver paste 42a is disposed in the second area 42b on the first substrate 10. For example, the silver paste 42a is composed of Y-shaped portions facing both sides in the first direction X and a single linear portion extending along the second direction Y. The silver paste 42a contains silver particles, a thermosetting resin, and a solvent as main materials.

[0108] Next, the structure including the second substrate 20 and the plurality of light-emitting elements 30 is brought into contact with the sintered silver paste 41a and the silver paste 42a, and the structure is pressed toward the first substrate 10. As a result, the sintered silver paste 41a is pushed away in the first area 41b, and the silver paste 42a is pushed away in the second area 42b.

[0109] Next, a structure including a first substrate 10, a sintered silver paste 41a, a silver paste 42a, a second substrate 20, and a plurality of light-emitting elements 30 is heated to a temperature of, for example, 200°C. As a result, the solvent in the sintered silver paste 41a volatilizes, and the silver particles are sintered to each other to form a first portion 41. At this time, the silver particles included in the first portion 41 react with the metal layer 21 and are joined. In addition, the solvent in the silver paste 42a volatilizes, and the resin cures. As a result, the silver paste 42a cures to form a second portion 42.

[0110] In this way, the joining member 40 is formed, and the second substrate 20 is joined to the first substrate 10. At this time, in a plan view, the shape of the first portion 41 is a substantially rectangular shape in which the length L41x in the first direction X is equal to or less than the length L41y in the second direction Y. The shapes of the two second portions 42 are also substantially rectangular in a plan view.

[0111] Next, as Figure 3 shown, the wire 62 is joined to the terminals of the first substrate 10 and the terminals of the second substrate 20. Next, the phosphor layer 61 is disposed on the LED array 32. Next, the resin member 63 is formed so as to cover the wire 62. In this way, the light-emitting device 1 is manufactured.

[0112] Next, the operation and effects of the present embodiment will be described.

[0113] Figure 6 is a schematic cross-sectional view showing the occurrence of warping in the light-emitting device according to the comparative example.

[0114] Figure 7 is a schematic cross-sectional view showing the occurrence of warping in the light-emitting device according to the present embodiment.

[0115] As Figure 6 shown, in the light-emitting device 101 according to the comparative example, a joining member 140 is disposed between the first substrate 10 and the second substrate 20. The entire joining member 140 is formed of sintered silver.

[0116] At room temperature, when the sintered silver paste 41a is disposed on the first substrate 10 and the second substrate 20 is disposed thereon, no warping occurs in the structure 160 including the first substrate 10 and the second substrate 20.

[0117] Next, when heating to, for example, 200°C to sinter the sintered silver paste 41a, the thermal expansion rate of the first substrate 10 with copper as the main component is larger than that of the second substrate 20 with silicon as the main component. Therefore, the first substrate 10 expands significantly more than the second substrate 20. At this stage, the sintered silver paste 41a has not been completely sintered, so the Young's modulus is low. Therefore, the expansion of the first substrate 10 is not much restricted by the second substrate 20, and no large warping occurs in the structure 160. After that, the sintering of the sintered silver paste 41a is completed to form the joining member 140.

[0118] After that, when cooling the structure 160 to room temperature, the first substrate 10 shrinks significantly more than the second substrate 20. However, at this stage, the second substrate 20 is firmly bonded to the first substrate 10 through the joining member 140 composed of the sintered silver. Therefore, the shrinkage of the first substrate 10 is restricted by the second substrate 20, and warping such as upward convexity occurs in the structure 160. This warping also remains in the manufactured light-emitting device 101. When warping occurs in the light-emitting device 101, the optical precision decreases.

[0119] In contrast, as Figure 7 shown, in the light-emitting device 1 according to the present embodiment, the joining member 40 includes a first portion 41 and a second portion 42 having a lower Young's modulus than the first portion 41. Therefore, when cooling the structure 60 including the first substrate 10 and the second substrate 20 to room temperature after forming the joining member 40, the shrinkage of the first substrate 10 is absorbed to some extent by the second portion 42 of the joining member 40. As a result, warping of the light-emitting device 1 can be suppressed.

[0120] Here, when ε represents strain (amount of extension), σ represents stress (load), and E represents Young's modulus, Young's modulus can be obtained by the calculation formula E = σ / ε. As a specific method for obtaining Young's modulus, the Young's modulus of each of the first portion 41 and the second portion 42 can be obtained by applying a load to the first portion 41 and the second portion 42 and measuring the amount of extension of the first portion 41 and the second portion 42 when the load is applied.

[0121] As Figure 4 shown, the length L20x of the second substrate 20 in the first direction X is longer than the length L20y of the second substrate 20 in the second direction Y. Therefore, in the light-emitting device 1, warping is more likely to occur along the first direction X than along the second direction Y. In the present embodiment, the shape of the first portion 41 that restricts the deformation of the first substrate 10 is such that the length L41x in the first direction X is equal to or less than the length L41y in the second direction Y. Therefore, the restriction in the first direction X is restrictive. As a result, warping of the light-emitting device 1 can be effectively suppressed.

[0122] In addition, in the light-emitting device 1 after manufacture, heat is generated when the light-emitting element 30 emits light. A part of the heat generated in the light-emitting element 30 is discharged to the outside via the second substrate 20, the bonding member 40, and the first substrate 10. Since the thermal conductivity of the first part 41 of the bonding member 40 is higher than that of the second part 42, the heat dissipation performance of the light-emitting device 1 is high. On the other hand, it is assumed that when the entire bonding member 40 is formed of silver paste, the occurrence of warping can be suppressed, but the heat dissipation performance becomes low.

[0123] According to the present embodiment, with respect to the first part 41 having a relatively high thermal conductivity and Young's modulus and the second part 42 having a relatively low thermal conductivity and Young's modulus, the second part 42 is disposed on both sides of the first part 41 in the first direction X, and the length L41x of the first part 41 in the first direction X is not greater than the length L41y of the first part 41 in the second direction Y, thereby realizing the light-emitting device 1 that can achieve both high heat dissipation performance and suppression of warping.

[0124] The light-emitting device 1 according to the present embodiment can be used, for example, as a light source of a headlamp of a motor vehicle. In this case, by individually controlling the plurality of light-emitting elements 30, the intensity distribution of the light emitted from the headlamp can be arbitrarily controlled, and the irradiation range can be selected. In this case, the brightness and calorific value of the light-emitting element 30 sometimes vary depending on the position in the LED array 32.

[0125] For example, in the case of high beam irradiation by the headlamp, a high current is supplied to a group of light-emitting elements 30 arranged at the center of the LED array 32, resulting in high brightness. A large amount of heat is generated from this group of light-emitting elements 30, so it is preferable that the first part 41 is disposed in the region directly below this group of light-emitting elements 30.

[0126] It should be noted that in the present embodiment, an example in which the first part 41 is formed of sintered silver and the second part 42 is formed of silver paste is shown, but it is not limited thereto. The first part 41 can also be formed of solder materials such as AuSn solder and SAC solder, for example. The second part 42 can also be formed of a resin-based adhesive containing fillers such as Al paste and graphene paste, or can be formed of a resin-based adhesive such as epoxy resin, silicone resin, and acrylic resin. The first part 41 can also be formed by plating with Cu, Au, Ag, etc. after the second part 42 is formed. It is only necessary that the first part 41 has higher thermal conductivity than the second part 42, and the second part 42 has lower Young's modulus than the first part 41.

[0127] <Second Embodiment>

[0128] Figure 8 It is a top view showing the bonding member of the light-emitting device according to the present embodiment.

[0129] Figure 9 This is a top view showing the process of disposing the sintered silver paste and the silver paste on the first substrate in the present embodiment.

[0130] As Figure 8 shown, in the light-emitting device 2 according to the present embodiment, in a top view, the boundary 43 between the first portion 41 and the second portion 42 of the joining member 40 is a curve that bulges outwards on both sides in the first direction X of the first portion 41. It should be noted that since the first portion 41 and the second portion 42 are three-dimensional objects, their boundary 43 is a two-dimensional surface, for example, a curved surface. However, in Figure 8 such a top view, the boundary 43 is represented by the intersection line between the upper surface of the joining member 40 and the boundary 43 as a curved surface. That is, in the top view, the first portion 41 and the second portion 42 are two-dimensionally represented, so their boundary 43 is represented by a one-dimensional line, for example, a curve.

[0131] As Figure 9 shown, the joining member 40 in the present embodiment can be realized, for example, by disposing the sintered silver paste 41a in a cross shape within the first region 41b and disposing the silver paste 42a in an X shape within the second region 42b respectively in the process of disposing the sintered silver paste and the silver paste on the first substrate 10.

[0132] According to the present embodiment, by setting the shape of the boundary 43 to a curve that bulges outwards on both sides in the first direction X of the first portion 41, it is possible to suppress the formation of acute-angled corners in the sintered first portion 41. Thereby, the concentration of thermal stress is alleviated, and damage to the second substrate 20 and the light-emitting element 30 caused by thermal stress can be suppressed. The structures, manufacturing methods, and effects other than the above in the present embodiment are the same as those in the first embodiment.

[0133] <Third Embodiment>

[0134] Figure 10 This is a cross-sectional view showing the light-emitting device according to the present embodiment.

[0135] Figure 11 This is a top view showing the joining member of the light-emitting device according to the present embodiment.

[0136] Figure 12 This is a top view showing the process of disposing the sintered silver paste and the silver paste on the first substrate in the present embodiment.

[0137] As Figure 10 and Figure 11As shown, the light-emitting device 3 according to the present embodiment further includes a partitioning member 44 disposed between the first portion 41 and the second portion 42 of the bonding member 40. The material of the partitioning member 44 is not particularly limited as long as it has heat resistance that can withstand the manufacturing process of the light-emitting device 3, and is formed of, for example, metal or resin.

[0138] In the present embodiment, the shape of the partitioning member 44 is a frame shape, for example, a substantially elliptical ring shape in which the length in the second direction Y is longer than the length in the first direction X. The first portion 41 is disposed inside the partitioning member 44, and two second portions 42 are disposed on both sides of the partitioning member 44 in the first direction X. In the present embodiment, in a plan view, the partitioning member 44 is disposed inside the second substrate 20.

[0139] As Figure 12 shown, in the manufacturing method of the light-emitting device 3, in the step of disposing the sintered silver paste 41a and the silver paste 42a, the partitioning member 44 is disposed on the first substrate 10, and the sintered silver paste 41a is disposed in a cross shape inside the partitioning member 44, and the silver paste 42a is disposed in an X shape on both sides of the partitioning member 44 in the first direction X. However, the shapes of the sintered silver paste 41a and the silver paste 42a when disposed are not limited to the cross shape and the X shape, and can be any shape.

[0140] According to the present embodiment, by providing the partitioning member 44, the positions, shapes, and thicknesses of the first portion 41 and the second portion 42 can be controlled more precisely. The structures, manufacturing methods, and effects other than the above in the present embodiment are the same as those in the second embodiment.

[0141] <First Modification of the Third Embodiment>

[0142] Figure 13 is a plan view showing a bonding member of the light-emitting device according to this modification.

[0143] As Figure 13 shown, in the light-emitting device 3a according to this modification, the partitioning member 44a is in a frame shape, and in a plan view, a part of the partitioning member 44a protrudes from the second substrate 20. More specifically, in a plan view, the shape of the partitioning member 44a is a substantially elliptical shape in which the length in the second direction Y is longer than the length in the first direction X, and both end portions in the second direction Y of the partitioning member 44a protrude from the second substrate 20. In addition, in a plan view, both end portions in the second direction Y in the substantially elliptical space surrounded by the partitioning member 44a also protrude from the second substrate 20.

[0144] According to this modification example, by allowing a part of the dividing member 44a to protrude from the second substrate 20 in a plan view, when the sintered silver paste 41a is sintered, the voids and solvents contained in the sintered silver paste 41a can be released to the outside of the joining member 40. As a result, the quality of the sintered silver after sintering is improved. The structures, manufacturing methods, and effects other than the above in this modification example are the same as those in the third embodiment.

[0145] <Third Embodiment, Second Modification Example>

[0146] Figure 14 It is a plan view showing the joining member of the light-emitting device according to this modification example.

[0147] As Figure 14 shown, in the light-emitting device 3b according to this modification example, in a plan view, the shape of the dividing member 44b is a frame shape and is substantially rectangular. The length of the dividing member 44b in the second direction Y is longer than the length of the dividing member 44b in the first direction X. The structures, manufacturing methods, and effects other than the above in this modification example are the same as those in the third embodiment. It should be noted that, similarly to the first modification example of the third embodiment, a part of the dividing member 44b may be provided so as to protrude from the second substrate 20.

[0148] <Third Embodiment, Third Modification Example>

[0149] Figure 15 It is a plan view showing the joining member of the light-emitting device according to this modification example.

[0150] As Figure 15 shown, in the light-emitting device 3c according to this modification example, in a plan view, the shape of the dividing member 44c is not a frame shape but two bar shapes with the second direction Y as the long side direction. The two dividing members 44c are arranged separately from each other in the first direction X. The first part 41 is arranged between the two dividing members 44c, and the second parts 42 are arranged on both sides of the two dividing members 44c in the first direction X. The structures, manufacturing methods, and effects other than the above in this modification example are the same as those in the third embodiment.

[0151] <Fourth Embodiment>

[0152] Figure 16 It is a cross-sectional view showing the light-emitting device according to this embodiment.

[0153] Figure 17 It is a plan view showing the joining member of the light-emitting device according to this embodiment.

[0154] Figure 18 It is a plan view showing the process of arranging the sintered silver paste and the silver paste on the first substrate in this embodiment.

[0155] As Figure 16 and Figure 17 shown, in the light-emitting device 4 according to the present embodiment, the first substrate 10 has a convex portion 14 on the upper surface side. The convex portion 14 is formed of, for example, copper. The convex portion 14 is disposed between the first portion 41 and the second portion 42 of the bonding member 40.

[0156] In a plan view, the shape of the convex portion 14 is a frame shape, for example, a substantially elliptical ring shape. The length of the convex portion 14 in the second direction Y is greater than or equal to the length of the convex portion 14 in the first direction X. The first portion 41 is disposed inside the convex portion 14, and two second portions 42 are disposed on both sides of the convex portion 14 in the first direction X, that is, outside the convex portion 14. In the present embodiment, in a plan view, the convex portion 14 is disposed inside the second substrate 20.

[0157] As Figure 18 shown, in the manufacturing method of the light-emitting device 4 according to the present embodiment, in the step of disposing the sintered silver paste 41a and the uncured silver paste 42a, the sintered silver paste 41a is disposed in a cross shape inside the convex portion 14 of the first substrate 10, and the silver paste 42a is disposed in an X shape on both sides of the convex portion 14 in the first direction X, that is, outside the convex portion 14. However, the shapes of the sintered silver paste 41a and the silver paste 42a when disposed are not limited to a cross shape and an X shape, and may be any shape. The structures, manufacturing methods, and functions and effects other than the above in the present embodiment are the same as those in the third embodiment.

[0158] <Fourth Embodiment Variation>

[0159] Figure 19 is a cross-sectional view showing the light-emitting device according to the present variation.

[0160] Figure 20 is a plan view showing the step of disposing the sintered silver paste and the silver paste on the first substrate in the present variation.

[0161] As Figure 19 shown, in the light-emitting device 4a according to the present variation, the first substrate 10 has a groove 15 on the upper surface side. Moreover, at least one, for example, both of a part of the first portion 41 and a part of the second portion 42 of the bonding member 40 are disposed in the groove 15. Therefore, in a plan view, the boundary 43 between the first portion 41 and the second portion 42 overlaps with the groove 15.

[0162] As Figure 20As shown, in the method for manufacturing the light-emitting device 4a according to this modification example, the sintered silver paste 41a before sintering is disposed within the region surrounded by the groove 15 on the first substrate 10, and the silver paste 42a is disposed on both sides of the groove 15 in the first direction X. Thus, when the sintered silver paste 41a and the silver paste 42a are pressed and expanded by the second substrate 20, they fall into the groove 15, thereby preventing the expansion beyond the groove 15. As a result, in a plan view, the position of the boundary 43 can be overlapped with the groove 15.

[0163] In this way, the position of the boundary 43 is controlled by the groove 15, and the positions and shapes of the first part 41 and the second part 42 can be controlled with high precision. The structures, manufacturing methods, and effects other than the above in this modification example are the same as those in the fourth embodiment.

[0164] <Fifth Embodiment>

[0165] Figure 21 It is a cross-sectional view showing the light-emitting device according to this embodiment.

[0166] As Figure 21 shown, in the light-emitting device 5 according to this embodiment, the first substrate 10 has a recess 16 on its upper surface side. Moreover, in a plan view, the first part 41 of the joining member 40 is located within the recess 16. On the other hand, in a plan view, the second part 42 of the joining member 40 is located on both sides of the recess 16 in the first direction X.

[0167] Therefore, the thickness of the first part 41, that is, the length in the third direction Z, is larger than the thickness of the second part 42. In one example, the thickness of the first substrate 10 is 500 μm, and the depth of the recess 16 is 50 μm. In addition, the thickness of the first part 41 is 60 μm or more and 80 μm or less, and the thickness of the second part 42 is 10 μm or more and 30 μm or less.

[0168] In this embodiment, by disposing the sintered silver paste 41a within the recess 16, the first part 41 can be formed within the recess 16 and in the region directly above it. Thus, the outer edge of the first part 41 can be defined by the outer edge of the recess 16, and the shape accuracy of the first part 41 is improved.

[0169] In addition, the thinner the first part 41 made of sintered silver, the higher the residual stress. Therefore, from the viewpoint of residual stress, a thicker first part 41 is preferred. On the other hand, the thinner the second part 42 made of silver paste, the better the heat dissipation. Therefore, from the viewpoint of heat dissipation, a thinner second part 42 is preferred. In this embodiment, by making the first part 41 thicker than the second part 42, the heat dissipation can be improved while suppressing the residual stress. The structures, manufacturing methods, and effects other than the above in this embodiment are the same as those in the first embodiment.

[0170] <Sixth Embodiment>

[0171] Figure 22 It is a cross-sectional view showing the light-emitting device according to the present embodiment.

[0172] Figure 23A It is a top view showing the joining member of the light-emitting device according to the present embodiment.

[0173] Figure 23B It is a bottom view showing the second substrate of the light-emitting device according to the present embodiment.

[0174] As Figure 22 , Figure 23A and Figure 23B shown, in the light-emitting device 6 according to the present embodiment, the metal layer 21 of the second substrate 20 is disposed only in a region facing the first portion 41 of the joining member 40. Accordingly, the first portion 41 of the joining member 40 is in contact with the metal layer 21 of the second substrate 20, and the second portion 42 of the joining member 40 is in contact with the semiconductor portion 22 of the second substrate 20. However, in a top view, the outer edge of the metal layer 21 does not necessarily have to coincide strictly with the boundary 43 between the first portion 41 and the second portion 42.

[0175] The sintered silver forming the first portion 41 reacts with the metal layer 21 and joins to the second substrate 20. Therefore, the first portion 41 is preferably in contact with the metal layer 21. On the other hand, regarding the silver paste forming the second portion 42, the joining strength with silicon is higher than the joining strength with metal. Therefore, the second portion 42 is preferably in contact with the semiconductor portion 22. In the present embodiment, raw materials with good compatibility are joined to each other, and thus the joining strength between the first substrate 10 and the second substrate 20 is high. The structures, manufacturing methods, and functions and effects other than the above in the present embodiment are the same as those in the first embodiment.

[0176] <Seventh Embodiment>

[0177] Figure 24 It is a partially enlarged cross-sectional view showing the light-emitting device according to the present embodiment.

[0178] As Figure 24As shown, in the light-emitting device 7 according to the present embodiment, the end of the first portion 41 of the bonding member 40 climbs onto the end of the second portion 42. Therefore, in a plan view, a part of the first portion 41 overlaps with a part of the second portion 42. It should be noted that the end of the second portion 42 may also climb onto the end of the first portion 41. In the present embodiment, in a plan view, the boundary 43 between the first portion 41 and the second portion 42 becomes a region having a width. In this case, as described above, in a plan view, the intersection line between the upper surface of the bonding member 40 and the boundary 43 is represented as the boundary 43. In a plan view, the boundary 43 defined in this way may also be a curve protruding to both sides in the first direction X of the first portion 41.

[0179] In the present embodiment, near the boundary 43, a part of the silver contained in the sintered silver of the first portion 41 is melt-bonded to a part of the silver contained in the silver paste of the second portion 42. Due to the effect of such silver melt-bonding and the anchoring effect between the first portion 41 and the second portion 42, the first portion 41 and the second portion 42 are not easily peeled off. As a result, the bonding strength between the first substrate 10 and the second substrate 20 is improved. The structures, manufacturing methods, and functions and effects other than the above in the present embodiment are the same as those in the first embodiment.

[0180] <Test Example>

[0181] Figures 25A - 25D It is a plan view showing the arrangement of the sintered silver paste and the silver paste of each sample in this test example.

[0182] Figures 26A - 26D It is a plan view showing the bonding member of each sample in this test example.

[0183] Figure 27 It is a graph showing the warpage amount of each sample in this test example, with the sample taken as the horizontal axis and the warpage amount taken as the vertical axis.

[0184] In this test example, a plurality of samples obtained by bonding the second substrate 20 to the first substrate 10 via the bonding member 40 were produced. Among the samples, the arrangements of the first portion 41 and the second portion 42 in the bonding member 40 were different. After sintering the sintered silver paste 41a and curing the silver paste 42a to form the bonding member 40, the warpage amount of each sample at a temperature of 50 °C was measured.

[0185] As Figure 25A and Figure 26A shown, in the sample S0 according to Comparative Example 1, the length of the first portion 41 in the first direction X is longer than the length of the first portion 41 in the second direction Y. It should be noted that Figure 25A and Figure 26A Comparative Example 1 shown is relative to Figure 6For the comparative example shown, other examples.

[0186] As Figure 25B and Figure 26B As shown, the sample S1 related to Example 1 corresponds to the light-emitting device related to the above-described first embodiment, and the length of the first portion 41 in the first direction X is shorter than the length of the first portion 41 in the second direction Y.

[0187] As Figure 25C and Figure 26C As shown, the sample S2 related to Example 2 corresponds to the light-emitting device related to the above-described second embodiment, the length of the first portion 41 in the first direction X is shorter than the length of the first portion 41 in the second direction Y, and the boundary 43 is a curve protruding to both sides in the first direction X of the first portion 41.

[0188] As Figure 25D and Figure 26D As shown, the sample S3 related to Example 3 corresponds to the light-emitting device related to the above-described first embodiment, and the length of the first portion 41 in the first direction X is shorter than that of the sample S1.

[0189] As Figure 27 As shown, the warpage amount of the sample S1 related to Example 1 is reduced to less than half compared with the sample S0 related to Comparative Example 1. The warpage amounts of the sample S2 related to Example 2 and the sample S3 related to Example 3 are smaller than that of the sample S1 related to Example 1.

[0190] The above-described respective embodiments and their modified examples are examples in which the present invention is specifically implemented, and the present invention is not limited to these embodiments and modified examples. For example, inventions obtained by adding, deleting, or changing several constituent elements or processes in the above-described respective embodiments and respective modified examples are also included in the present invention. In addition, the above-described respective embodiments and respective modified examples can be implemented in combination with each other.

[0191]

Industrial Applicability

[0192] The light-emitting device of the present disclosure can be used, for example, as a light source for a headlamp of a motor vehicle.

Claims

1. A light emitting device, wherein: The light emitting device comprises: a first substrate; a second substrate disposed on the first substrate and having a shape long in a first direction in a plan view, and having a thermal expansion coefficient different from that of the first substrate; A plurality of light emitting elements, which are arranged on the second substrate; as well as a bonding member bonding the second substrate to the first substrate, The joining member has: a first portion, wherein a length of the first portion in the first direction is less than a length of the first portion in a second direction orthogonal to the first direction; as well as The second portion is disposed on both sides of the first portion in the first direction, the Young's modulus of the second portion is lower than that of the first portion, and the thermal conductivity of the second portion is lower than that of the first portion.

2. The light emitting device according to claim 1, wherein: In a plan view, a boundary between the first portion and the second portion is a curved line that bulges toward both sides of the first portion in the first direction.

3. The light emitting device according to claim 1 or 2, wherein: The light emitting device further includes a partitioning member disposed between the first portion and the second portion.

4. The light emitting device according to claim 3, wherein: The dividing member is frame-shaped, In a plan view, a portion of the partition member extends from the second substrate.

5. The light emitting device according to claim 1 or 2, wherein: In a plan view, a portion of the first portion overlaps a portion of the second portion.

6. The light emitting device according to claim 1 or 2, wherein: The first substrate has a convex portion on the upper surface side, The convex portion is disposed between the first portion and the second portion.

7. The light emitting device according to claim 1 or 2, wherein: The first substrate has a groove on the upper surface side. In a plan view, a boundary between the first portion and the second portion overlaps with the groove.

8. The light emitting device according to claim 1 or 2, wherein: The first substrate has a recessed portion on the upper surface side. In a plan view, the first portion is located in the recess.

9. The light emitting device according to any one of claims 1 to 8, wherein: The second substrate has: Semiconductor segment; as well as a metal layer disposed on the lower surface side of the semiconductor portion, The first portion is in contact with the metal layer, The second portion is in contact with the semiconductor portion.

10. The light emitting device according to any one of claims 1 to 9, wherein: The first substrate comprises metal, The second substrate includes a semiconductor.

11. The light emitting device according to any one of claims 1 to 10, wherein: The first portion comprises sintered silver, The second part comprises a cured silver paste.

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