Wavelength conversion member, light source device, and method for manufacturing wavelength conversion member

Abstract

The wavelength conversion member includes: a ceramic phosphor that converts the wavelength of incident light; a heat dissipation member that releases the heat of the ceramic phosphor to the outside; and a solder layer that joins the ceramic phosphor and the heat dissipation member. The solder layer includes a joint portion disposed between the ceramic phosphor and the heat dissipation member and an overflow portion that overflows outward from the outer peripheral portion of the ceramic phosphor. The overflow portion is separated from the side surface formed on the outer peripheral portion of the ceramic phosphor. In the solder layer, the maximum value of the thickness of the overflow portion is greater than the average value of the thickness of the joint portion.

Description

Technical Field

[0001] The present invention relates to a wavelength conversion member, a light source device, and a method for manufacturing a wavelength conversion member. Background Art

[0002] Conventionally, a wavelength conversion member that converts the wavelength of light emitted from a light source has been known. The wavelength conversion member generally includes a phosphor that converts the wavelength of incident light, a heat dissipation member, and a solder layer that joins the phosphor and the heat dissipation member, and the heat of the phosphor is dissipated by the heat dissipation member. At this time, voids contained in the solder cause a decrease in the thermal conductivity between the phosphor and the heat dissipation member. For example, in Patent Document 1, a technique for making the size of voids contained in the solder layer equal to or less than a predetermined value is disclosed. In addition, in Patent Document 2, a technique for increasing the contact area between the phosphor and the solder layer by forming a solder layer on the surface of the phosphor on the side of the heat dissipation member and the side surface of the phosphor is disclosed.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent No. 6020631

[0006] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2017-194706 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, even when the phosphor and the heat dissipation member are joined using the technique described in Patent Document 1, voids remain between the phosphor and the heat dissipation member, so it is difficult to further improve the thermal conductivity of the solder layer. In addition, when the phosphor and the heat dissipation member are joined using the technique described in Patent Document 2, when the wavelength conversion member is cooled after joining the phosphor and the heat dissipation member, due to the difference in the amount of thermal contraction between the solder layer and the phosphor, the phosphor is constrained by the solder layer formed on the side surface of the phosphor. Therefore, there is a risk that the phosphor is damaged due to the shrinkage of the solder layer. Thus, it is difficult to improve the thermal conductivity between the phosphor and the heat dissipation member while suppressing the breakage of the phosphor.

[0009] The present invention has been made to solve the above problems, and an object thereof is to provide a technique capable of achieving both an improvement in the thermal conductivity between a ceramic phosphor and a heat dissipation member and suppression of breakage of the ceramic phosphor in a wavelength conversion member.

[0010] Solutions to the Problems

[0011] The present invention has been made to solve at least a part of the above problems, and can be achieved by the following solutions.

[0012] (1) According to a technical solution of the present invention, a wavelength conversion member is provided. The wavelength conversion member includes: a ceramic phosphor that converts the wavelength of incident light; a heat dissipation member that releases the heat of the ceramic phosphor to the outside; and a solder layer that joins the ceramic phosphor and the heat dissipation member. The solder layer includes a joint portion disposed between the ceramic phosphor and the heat dissipation member, and an overflow portion that overflows outward from the outer peripheral portion of the ceramic phosphor. The overflow portion is separated from the side surface formed on the outer peripheral portion of the ceramic phosphor. In the solder layer, the maximum value of the thickness of the overflow portion is greater than the average value of the thickness of the joint portion.

[0013] With this structure, in the solder layer, the maximum value of the thickness of the overflow portion is greater than the average value of the thickness of the joint portion. The overflow portion is formed when the solder between the ceramic phosphor and the heat dissipation member is extruded outward from the outer peripheral portion of the ceramic phosphor during the joining of the ceramic phosphor and the heat dissipation member. At this time, the voids in the solder between the ceramic phosphor and the heat dissipation member move together with the extruded solder and float in the solder outside the outer peripheral portion of the ceramic phosphor. Thus, compared with the case where the voids do not move, the number of voids in the joint portion becomes smaller. Therefore, the heat transfer between the ceramic phosphor and the heat dissipation member is less likely to be hindered by the voids. Accordingly, the thermal conductivity between the ceramic phosphor and the heat dissipation member can be improved. In addition, the overflow portion is separated from the side surface of the ceramic phosphor. When the temperature is lowered after joining the ceramic phosphor and the heat dissipation member, even if shrinkage occurs, the ceramic phosphor will not be restricted. Thus, breakage of the ceramic phosphor due to shrinkage of the solder layer can be suppressed. In this way, improvement of the thermal conductivity between the ceramic phosphor and the heat dissipation member and suppression of breakage of the ceramic phosphor can be achieved concurrently. In addition, since the thermal conductivity between the ceramic phosphor and the heat dissipation member is improved, the durability of the ceramic phosphor is improved, and a decrease in luminous efficiency can be suppressed.

[0014] (2) According to another technical solution of the present invention, a wavelength conversion member is provided. The wavelength conversion member includes: a ceramic phosphor that converts the wavelength of incident light; a heat dissipation member that releases the heat of the ceramic phosphor to the outside; and a solder layer that joins the ceramic phosphor and the heat dissipation member. The solder layer includes a joint portion disposed between the ceramic phosphor and the heat dissipation member, and an overflow portion that overflows outward from the outer peripheral portion of the ceramic phosphor. The porosity of the joint portion is less than the porosity of the overflow portion.

[0015] With this structure, the porosity of the joint portion is smaller than that of the overflow portion. Here, the porosity refers to the ratio of the area of the projection pattern of the voids on the imaginary plane to the area of the projection pattern of a part of the solder layer when a part of the solder layer and the voids contained in a part of the solder layer are projected onto an imaginary plane perpendicular to the central axis of the wavelength conversion member. Thus, heat conduction between the ceramic phosphor and the heat sink member based on the joint portion is not easily hindered by voids. Therefore, the thermal conductivity between the ceramic phosphor and the heat sink member can be improved.

[0016] (3) According to another technical solution of the present invention, there is provided a wavelength conversion member. The wavelength conversion member includes: a ceramic phosphor that converts the wavelength of incident light; a heat sink member that releases the heat of the ceramic phosphor to the outside; and a solder layer that joins the ceramic phosphor and the heat sink member. The solder layer includes a joint portion disposed between the ceramic phosphor and the heat sink member, and an overflow portion that overflows outward from the outer peripheral portion of the ceramic phosphor. The porosity of the central portion of the joint portion through which the central axis of the wavelength conversion member passes is smaller than the porosity of the other portions of the joint portion except the central portion.

[0017] With this structure, the central portion of the joint portion is located between the central portion of the ceramic phosphor that is easily irradiated with light and generates more heat and the heat sink member. In addition, the porosity of the central portion of the joint portion is smaller than the porosity of the portions of the joint portion other than the central portion. Thus, the central portion of the joint portion has better thermal conductivity in the joint portion, and therefore the heat generated in the central portion of the ceramic phosphor due to the irradiated light can be quickly transferred to the heat sink member. Therefore, by making the porosity of the central portion smaller than that of the other portions of the joint portion, the thermal conductivity between the ceramic phosphor and the heat sink member can be improved.

[0018] (4) In the wavelength conversion member of the above technical solution, it may also be that the overflow portion is formed to surround the outer peripheral portion of the ceramic phosphor over the entire circumference. With this structure, when joining the ceramic phosphor and the heat sink member, the solder between the ceramic phosphor and the heat sink member overflows over the entire circumference of the outer peripheral portion of the ceramic phosphor. Thus, compared with the case where the overflow portion is formed to surround a part of the outer peripheral portion of the ceramic phosphor, the distance that the voids between the ceramic phosphor and the heat sink member move to the outside of the outer peripheral portion of the ceramic phosphor becomes shorter, and therefore, the number of voids in the joint portion further decreases. Therefore, the thermal conductivity between the ceramic phosphor and the heat sink member can be further improved.

[0019] (5) In the wavelength conversion member of the above technical solution, it is also possible that the maximum value of the thickness of the overflow portion is more than twice and less than 10 times the average value of the thickness of the joint portion. With this structure, the voids moving from between the ceramic phosphor and the heat dissipation member to the outside of the outer periphery of the ceramic phosphor are likely to float in the solder layer on the outside of the outer periphery of the ceramic phosphor. Thus, the voids between the ceramic phosphor and the heat dissipation member are likely to move to the outside of the outer periphery of the ceramic phosphor. Therefore, the number of voids in the joint portion becomes even smaller. Consequently, the thermal conductivity between the ceramic phosphor and the heat dissipation member can be further improved.

[0020] (6) In the wavelength conversion member of the above technical solution, it is also possible that the height of the overflow portion measured from the heat dissipation member is lower than the height of the light incident surface of the ceramic phosphor for light incident measured from the heat dissipation member. With this structure, it is possible to suppress the light emitted from the ceramic phosphor from being blocked by the overflow portion whose maximum thickness is larger than the average value of the thickness of the joint portion.

[0021] (7) According to another technical solution of the present invention, a light source device is provided. The light source device includes: the above wavelength conversion member; and a light source that irradiates light onto the ceramic phosphor. With this structure, the light source device emits light having a wavelength different from the wavelength of the light irradiated by the light source onto the ceramic phosphor to the outside. In the wavelength conversion member having a ceramic phosphor that converts the wavelength of light, since the number of voids included in the joint portion of the solder layer between the ceramic phosphor and the heat dissipation member is relatively small, the heat conduction between the ceramic phosphor and the heat dissipation member at the joint portion is not easily blocked by the voids. Thus, it is possible to suppress a decrease in the light emission intensity of the light source device caused by temperature quenching. In addition, since the overflow portion is separated from the side surface of the ceramic phosphor, it is possible to suppress the ceramic phosphor from being damaged due to the shrinkage of the solder layer. Thus, it is possible to suppress a decrease in the light emission intensity of the light source device caused by the damage of the ceramic phosphor.

[0022] (8) According to still another technical solution of the present invention, a manufacturing method of a wavelength conversion member is provided. The manufacturing method of the wavelength conversion member includes: a preparation step in which a ceramic phosphor for converting the wavelength of incident light and a heat dissipation member to be joined to the ceramic phosphor are prepared; a joining step in which the ceramic phosphor and the heat dissipation member are joined together by a solder layer; and a processing step in which, after the joining step, the solder layer is processed by this processing step. In the joining step, the solder layer forms a joining portion and an overflow portion. The joining portion is disposed between the ceramic phosphor and the heat dissipation member, and the overflow portion overflows outward from the outer peripheral portion of the ceramic phosphor. The maximum value of the thickness of the overflow portion is greater than the average value of the thickness of the joining portion. In the processing step, at least a part of the overflow portion including a part separated from the side surface formed on the outer peripheral portion of the ceramic phosphor is removed.

[0023] With this structure, in the joining step, the voids in the solder between the ceramic phosphor and the heat dissipation member move together with the solder from between the ceramic phosphor and the heat dissipation member and float in the solder outside the outer peripheral portion of the ceramic phosphor. Thus, compared with the case where the voids do not move, the number of voids in the joining portion becomes smaller, so that the thermal conductivity between the ceramic phosphor and the heat dissipation member can be improved. After that, in the processing step, a process of removing at least a part of the overflow portion including a part separated from the side surface of the ceramic phosphor is performed, thereby being able to suppress breakage of the ceramic phosphor caused by shrinkage of the solder layer. In this way, it is possible to achieve both improvement of the thermal conductivity between the ceramic phosphor and the heat dissipation member and suppression of breakage of the ceramic phosphor.

[0024] In addition, the present invention can be implemented in various aspects. For example, it can be implemented in the form of a light emitting system using a wavelength conversion member or a light source device, a manufacturing method of a light source device or a light emitting system, a computer program for causing a computer to execute the manufacturing of a wavelength conversion member or a light source device, a server device for distributing the computer program, a non-temporary storage medium storing the computer program, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of the light source device of the first embodiment.

[0026] Figure 2 is a top view of the wavelength conversion member.

[0027] Figure 3 is a diagram for explaining a method of calculating the porosity of the solder layer.

[0028] Figure 4 is a diagram for explaining the manufacturing method of the wavelength conversion member.

[0029] Figure 5 This is a diagram for explaining the content of the first evaluation test of the wavelength conversion member.

[0030] Figure 6 This is a diagram for explaining the results of the first evaluation test of the wavelength conversion member.

[0031] Figure 7 This is a diagram for explaining the results of the second evaluation test of the wavelength conversion member.

[0032] Figure 8 This is a cross-sectional view of a modified example of the wavelength conversion member of the first embodiment.

[0033] Figure 9 This is a top view of another modified example of the wavelength conversion member of the first embodiment. Detailed implementation mode

[0034] <First embodiment>

[0035] Figure 1 This is a schematic diagram of the light source device 5 of the first embodiment. Figure 2 This is a top view of the wavelength conversion member 1. The light source device 5 of the present embodiment includes a wavelength conversion member 1 and a light source 6. When the wavelength conversion member 1 is irradiated with light L1 emitted from a light source 6 such as an external light emitting diode (LED: Light Emitting Diode) or a semiconductor laser (LD: Laser Diode), light L2 having a wavelength different from that of the light L1 is generated. The wavelength conversion member 1 is used, for example, in various optical devices such as headlamps, lighting, and projectors. The wavelength conversion member 1 includes a ceramic phosphor 10, a heat dissipation member 20, and a solder layer 30. In addition, in Figure 1 For convenience of explanation, the thickness relationships of the ceramic phosphor 10, the heat dissipation member 20, and the solder layer 30 are illustrated in a manner different from the actual thickness relationships.

[0036] The ceramic phosphor 10 is composed of a ceramic sintered body and converts the wavelength of the light incident from the incident surface 11. The ceramic sintered body has: a fluorescent phase, which has fluorescent crystal grains as the main body; and a light-transmitting phase, which has light-transmitting crystal grains as the main body. Preferably, the crystal grains of the light-transmitting phase have a composition represented by the chemical formula Al2O3, and the crystal grains of the fluorescent phase have a composition represented by the chemical formula A3B5O 12 :Ce (so-called garnet structure). "A3B5O 12 :Ce" means that Ce is dissolved in A3B5O 12 and a part of the element A is replaced by Ce.

[0037] Chemical formula A3B5O 12: Element A and element B in Ce are each composed of at least one element selected from the following element groups.

[0038] Element A: Lanthanide elements other than Sc, Y, and Ce (where element A may also contain Gd)

[0039] Element B: Al (where element B may also contain Ga)

[0040] By using the ceramic sintered body as the ceramic phosphor 10, light scattering occurs at the interface between the fluorescent phase and the light-transmitting phase, and the angular dependence of the light color can be reduced. Thereby, the color homogeneity can be improved. In addition, the material of the ceramic phosphor 10 is not limited to the above materials.

[0041] A metal film (not shown) is disposed on the main surface 12 of the ceramic phosphor 10 on the side of the heat dissipation member 20. For this metal film, the wettability of the solder is good. Therefore, the adhesion between the ceramic phosphor 10 and the solder layer 30 can be improved, and the metal film reflects the light transmitted through the ceramic phosphor 10 and the light generated in the ceramic phosphor 10, thereby improving the luminous efficiency of the wavelength conversion member 1.

[0042] The heat dissipation member 20 is, for example, a rectangular flat member formed of a material having a higher thermal conductivity than the ceramic phosphor 10, such as copper, a copper-molybdenum alloy, a copper-tungsten alloy, aluminum, or aluminum nitride. A bonding film (not shown) is disposed on the main surface 21 of the heat dissipation member 20 on the side of the ceramic phosphor 10. For this bonding film, the wettability of the solder is good. Therefore, the adhesion between the heat dissipation member 20 and the solder layer 30 can be improved. The heat dissipation member 20 releases the heat of the ceramic phosphor 10 transmitted through the solder layer 30 to the outside. In addition, the heat dissipation member 20 may be a member having a single-layer structure formed of the above materials, or may be a member having a multi-layer structure formed of the same or different materials.

[0043] The solder layer 30 is disposed between the ceramic phosphor 10 and the heat dissipation member 20 and is formed of gold and tin. The solder layer 30 joins the ceramic phosphor 10 and the heat dissipation member 20. As Figure 1 shown, the solder layer 30 has a joining portion 31 and an overflow portion 32. The joining portion 31 is disposed in the part of the solder layer 30 located under the ceramic phosphor 10, that is, between the ceramic phosphor 10 and the heat dissipation member 20. The joining portion 31 contacts the main surface 12 of the ceramic phosphor 10 and the main surface 21 of the heat dissipation member 20, and joins the ceramic phosphor 10 and the heat dissipation member 20.

[0044] The overflow portion 32 is located outside the joining portion 31. Specifically, as Figure 1As shown, the overflow portion 32 is formed in the following shape: on the main surface 21 of the heat dissipation member 20, it overflows from the outer peripheral portion 13 of the ceramic phosphor 10 to the outside of the ceramic phosphor 10 in a state of being connected to the outer peripheral portion of the joint portion 31. In the present embodiment, as Figure 2 shown, the overflow portion 32 is formed to surround the outer peripheral portion 13 of the ceramic phosphor 10 over the entire circumference. As Figure 1 shown, the inner wall 33 of the overflow portion 32 is separated from the side surface 14 formed on the outer peripheral portion 13 of the ceramic phosphor 10. Thus, the vertex 34 of the overflow portion 32 (refer to Figure 1 ) is formed at a position away from the outer peripheral portion 13 of the ceramic phosphor 10. As Figure 1 shown, the height H1 of the vertex 34 from the main surface 21 of the heat dissipation member 20 is lower than the height H2 of the incident surface 11 of the ceramic phosphor 10 where the light L1 is incident from the main surface 21 of the heat dissipation member 20.

[0045] In the solder layer 30 of the present embodiment, the maximum value of the thickness of the overflow portion 32 is greater than the average value of the thickness of the joint portion 31. Specifically, the maximum value of the thickness of the overflow portion 32 is more than twice and less than 10 times the average value of the thickness of the joint portion 31. Here, the thickness of the joint portion 31 means the average value of the thicknesses of 10 portions set at equal intervals in a cross-section perpendicular to the joint surface between the ceramic phosphor 10 and the solder layer 30 and the joint surface between the solder layer 30 and the heat dissipation member 20 and including the central axis A1 (refer to Figure 1 , Figure 2 ) of the wavelength conversion member 1.

[0046] The solder layer 30 contains voids V1 generated inside the solder layer 30 during the manufacture of the wavelength conversion member 1. In the solder layer 30 of the present embodiment, the porosity of the joint portion 31 is smaller than the porosity of the overflow portion 32. In addition, when a part between the central portion C10 of the ceramic phosphor 10 through which the central axis A1 of the wavelength conversion member 1 passes and the heat dissipation member 20 in the joint portion 31 is set as the central portion 31a, the porosity of the central portion 31a is smaller than the porosity of the other portion 31b of the joint portion 31 except the central portion 31a. Here, the central portion 31a is a part of the joint portion 31 through which the central axis A1 of the wavelength conversion member 1 passes. In the present embodiment, for example, the central portion 31a refers to a columnar portion whose cross-sectional shape perpendicular to the central axis A1 is a circular shape having a center on the central axis A1.

[0047] Here, a method for calculating the porosity of the solder layer 30 in the present embodiment will be described. The porosity in the present embodiment refers to the ratio of the area of the projected figure of the void V1 on the imaginary plane to the area of the projected figure of a part of the solder layer 30 when a part of the solder layer 30 and the void V1 contained in a part of the solder layer 30 are projected onto an imaginary plane perpendicular to the central axis A1 of the wavelength conversion member 1.

[0048] Figure 3 This is a diagram for explaining the method for calculating the porosity of the solder layer 30. Here, a cross-sectional view perpendicular to the central axis A1 of the wavelength conversion member 1, that is, Figure 3 a part 35 of the solder layer 30 shown in (a) will be described. A part 35 of the solder layer 30 is located between the ceramic phosphor 10 and the heat dissipation member 20, and in the state shown in Figure 3 (a), it contains a void V1. In addition, since Figure 3 (a) is a cross-sectional view, it is assumed that a part 35 of the solder layer 30 also contains voids V1 not shown here.

[0049] When calculating the porosity of the solder layer 30, an imaginary plane VP perpendicular to the central axis A1 is assumed, and a projected figure of a part 35 of the solder layer 30 projected onto the imaginary plane VP is made when observing a part 35 of the solder layer 30 as shown by the dotted arrow W1 in Figure 3 (a). Figure 3 (b) of shows this projected figure. Here, the projected figure P35 of a part 35 of the solder layer 30 on the imaginary plane VP is made into a square. At this time, the void V1 contained in a part 35 of the solder layer 30 is also projected onto the projected figure P35 as the projected figure PV1 of the void V1. Therefore, as shown in Figure 3 (b), the projected figures PV1 of the void V1 are scattered in the projected figure P35. The ratio of the total area of the projected figures PV1 of the void V1 to the area of this projected figure P35 becomes the porosity in the present embodiment. In addition, as shown in Figure 3 (b), when the void V1 is projected onto the imaginary plane VP, there are cases where the projected figures PV1 of the respective voids V1 overlap (for example, the projected figure PV2 in Figure 3 (b)). In this case, the area of the overlapping part is calculated as the area occupied by the projected figure of one void V1, and is not double-counted.

[0050] Next, a method for manufacturing the wavelength conversion member 1 will be described. First, as a preparation process, a metal film is formed on the main surface 12 of the ceramic phosphor 10 using vacuum evaporation or sputtering. In addition, a bonding film is deposited on the main surface 21 of the heat dissipation member 20. Next, as a bonding process, with a gold-tin solder foil sandwiched between the ceramic phosphor 10 and the heat dissipation member 20, heating is performed in a reflow furnace in a nitrogen atmosphere or a hydrogen atmosphere to bond the ceramic phosphor 10 and the heat dissipation member 20 together. At this time, the ceramic phosphor 10 and the heat dissipation member 20 are bonded in such a way that the molten gold-tin solder foil between the ceramic phosphor 10 and the heat dissipation member 20 overflows to the outside of the ceramic phosphor 10. In addition, when forming a bonding film on the surface of the heat dissipation member 20, film formation can also be performed by vacuum evaporation or sputtering. Alternatively, instead of using a gold-tin solder foil, a gold-tin solder paste can be applied.

[0051] Figure 4 FIG. is a diagram for explaining the manufacturing method of the wavelength conversion member 1. In Figure 4 (a) thereof, the ceramic phosphor 10, the heat dissipation member 20, and the gold-tin solder foil F1 before bonding are shown. As Figure 4 (a) of FIG. shows, a gold-tin solder foil F1 that is larger than the ceramic phosphor 10 and smaller than the heat dissipation member 20 is inserted between the metal film formed on the main surface 12 of the ceramic phosphor 10 and the bonding film formed on the main surface 21 of the heat dissipation member 20. When the ceramic phosphor 10 and the heat dissipation member 20 in a state where the gold-tin solder foil F1 is sandwiched are heated in a reflow furnace, the molten gold-tin solder foil F1 reacts with the metal film of the ceramic phosphor 10 and the bonding film of the heat dissipation member 20 to bond the ceramic phosphor 10 and the heat dissipation member 20 together. At this time, voids V1 are generated due to the gap between the metal film and the gold-tin solder foil F1, the gap between the bonding film and the gold-tin solder foil F1, and the gas mixed in during the plating process (refer to Figure 4 (b) of FIG.).

[0052] When a load is applied to the ceramic phosphor 10 and the heat dissipation member 20 to bond them together (refer to the hollow arrows F10, F20 shown in Figure 4 (b) of FIG.), in the molten solder 40 formed by melting the gold-tin solder foil F1, the central portion S41 located between the ceramic phosphor 10 and the heat dissipation member 20 moves toward the outside of the outer peripheral portion 13 of the ceramic phosphor 10. At this time, the voids V1 in the central portion S41 move toward the outer portion S42 of the molten solder 40 due to the flow of the solder in the central portion S41 ( Figure 4(b)'s dashed arrow D1). As the molten solder 40 flows from the central portion S41 to the outer portion S42, the outer portion S42 of the molten solder 40 bulges and becomes thicker than the central portion S41. Therefore, when the void V1 moves from the central portion S41 to the outer portion S42, the void V1 floats in the molten solder 40 at the outer portion S42 ( Figure 4 (b)'s dashed arrow D2). In the present embodiment, by adjusting the thickness and size when the Au—Sn solder foil F1 is inserted between the ceramic phosphor 10 and the heat sink member 20, and the load when the ceramic phosphor 10 and the heat sink member 20 are joined, the height of the outer portion S42 is adjusted. Thereby, the void V1 in the central portion S41 easily moves to the outer portion S42. Therefore, in the manufacturing method of the present embodiment, as Figure 4 (c) shows, the voids V1 in the molten solder 40 concentrate on the outer portion S42, and the number of voids V1 in the central portion S41 becomes smaller.

[0053] In the manufacturing method of the wavelength conversion member 1 of the present embodiment, when a load is applied to the ceramic phosphor 10 and the heat sink member 20 to join them, the outer portion S42 of the molten solder 40 surrounds the outer peripheral portion 13 of the ceramic phosphor 10 over the entire circumference. Thereby, the distance for the void V1 in the central portion S41 to move to the outer portion S42 becomes relatively short. Therefore, the number of voids V1 in the central portion S41 further becomes smaller.

[0054] When Figure 4 (c) shows the state of the ceramic phosphor 10 and the heat sink member 20 cooled, the central portion S41 of the molten solder 40 becomes the joint portion 31 of the solder layer 30, and the outer portion S42 becomes the overflow portion 32. The ceramic phosphor 10 and the heat sink member 20 are joined by the solder layer 30. At this time, as Figure 4 (c) shows, since the inner wall S43 of the outer portion S42 of the molten solder 40 separates from the side surface 14 of the ceramic phosphor 10, even if the ceramic phosphor 10 and the molten solder 40 that becomes the solder layer 30 contract due to cooling, the ceramic phosphor 10 is not restricted by the overflow portion 32.

[0055] Next, the content of the evaluation test for explaining the effect of the wavelength conversion member 1 of the present embodiment and the result of this evaluation test will be described. In this evaluation test, two evaluation tests described below are performed.

[0056] In the first evaluation test, the porosity of each part of the solder layer 30 was measured and these values were compared. In the first evaluation test, first, X-rays were irradiated to the solder layer 30, and the object part for which the porosity was to be measured was photographed. Next, based on the photographed results, voids with a diameter of 10 μm or more were counted, and the porosity of the object part was calculated. In addition, the porosity calculated here is obtained by using the method in Figure 3The porosity calculated by the method described in

[0057] Figure 5 FIG. is a view for explaining the content of the first evaluation test of the wavelength conversion member 1. Figure 5 (a) of FIG. is a plan view of the wavelength conversion member 1 used in the first evaluation test, Figure 5 and (b) of FIG. is Figure 5 a cross-sectional view taken along line A-A of (a) of FIG. In the first evaluation test, for the wavelength conversion member 1 including the ceramic phosphor 10 having a rectangular shape, the porosity of the joint portion 31, the porosity of the central portion 31a included in the joint portion 31, and the porosity of the overflow portion 32 are calculated. In the first evaluation test, the diameter W1 of the circular shape, which is the cross-sectional shape of the cylindrically shaped central portion 31a, is defined as half of the narrowest width W2 of the ceramic phosphor 10. Specifically, the diameter W1 of the central portion 31a is 4 mm, and the width W2 of the ceramic phosphor 10 is 8 mm. In addition, in Figure 5 (b) of FIG., the width W3 of the solder layer 30 is 9 mm. That is, the width of the portion that overflows from the ceramic phosphor 10 of the overflow portion 32 is 1 mm in total on both sides.

[0058] In addition, in Figure 5 the wavelength conversion member 1 shown in FIG., the thickness Th1 of the joint portion 31 is 10 μm, and the thickness Th2 of the overflow portion 32 is 17 μm. Therefore, the first evaluation test is performed using the wavelength conversion member 1 in which the ratio of the thickness Th2 of the overflow portion 32 to the thickness Th1 of the joint portion 31 is 1.7.

[0059] Figure 6 FIG. is a view for explaining the result of the first evaluation test of the wavelength conversion member 1. Figure 6 (a) of FIG. is a table showing the measurement results of the porosity in the first evaluation test, Figure 6 (b) of FIG. is a view schematically showing the distribution of voids V1 in the wavelength conversion member 1. It can be seen from the first evaluation test that the porosity (3.4%) of the joint portion 31 including the central portion 31a is smaller than the porosity (4.3%) of the overflow portion 32. This indicates that when the ceramic phosphor 10 and the heat dissipation member 20 are joined, the voids between the ceramic phosphor 10 and the heat dissipation member 20 move to the outside of the ceramic phosphor 10. Therefore, the number of voids V1 in the overflow portion 32 increases, and the number of voids V1 in the joint portion 31 decreases (see Figure 6 (b) of FIG.).

[0060] In addition, from the first evaluation test, it can be seen that in the joint portion 31, the porosity (2.8%) of the central portion 31a is less than the porosity (3.4%) of the entire joint portion 31. That is, it can be known that the porosity of the central portion 31a is less than the porosity of the other portion 31b of the joint portion 31 except the central portion 31a. Thus, the thermal conductivity of the central portion 31a between the portion C10 at the center of the ceramic phosphor 10, which is likely to generate more heat due to being easily irradiated with light, and the heat dissipation member 20 is higher than that of the other portions of the joint portion 31 except the central portion 31a.

[0061] Figure 7 FIG. is a diagram for explaining the second evaluation result of the wavelength conversion member 1. In the second evaluation test, the ratio of the thickness of the overflow portion 32 to the thickness of the joint portion 31 is set as Figure 7 shown in the table of (a) below as 1, 1.2, 1.5, 2, 5.3, 10, and the porosity of the joint portion 31 at this time is measured and these values are compared. Figure 7 (b) of Figure 7 and

[0062] FIG. is a diagram schematically showing the distribution of the voids V1 in the joint portion 31 and the overflow portion 32 when the ratio of the thickness of the overflow portion 32 to the thickness of the joint portion 31 is changed. In addition, the porosity in the second evaluation test is the same as the porosity calculated by the method described in the first evaluation test.

[0062] As Figure 7 shown in (a) of Figure 7 FIG., it can be seen that when the ratio of the thickness of the overflow portion 32 to the thickness of the joint portion 31 increases, the porosity of the joint portion 31 decreases. That is, when the thickness of the joint portion 31 is the same, the number of voids V1 contained in the joint portion 31 of the wavelength conversion member 1 with a larger thickness ratio ( Figure 7 FIG. (c)) is less than the number of voids V1 contained in the joint portion 31 of the wavelength conversion member 1 with a smaller thickness ratio ( Figure 7 FIG. (b)). In particular, as Figure 7 shown in (a) of

[0063] As described above, in the solder layer 30 of the wavelength conversion member 1 according to the present embodiment, the maximum value of the thickness of the overflow portion 32 is greater than the average value of the thickness of the joint portion 31. The overflow portion 32 is formed by extruding the solder between the ceramic phosphor 10 and the heat dissipation member 20 to the outside of the outer peripheral portion 13 of the ceramic phosphor 10 when the ceramic phosphor 10 and the heat dissipation member 20 are joined. At this time, the void V1 in the solder between the ceramic phosphor 10 and the heat dissipation member 20 moves together with the extruded solder, and floats in the molten solder 40 outside the outer peripheral portion 13 of the ceramic phosphor 10. Thus, compared with the case where the voids do not move, the number of voids V1 in the joint portion 31 becomes smaller. Therefore, the heat transfer between the ceramic phosphor 10 and the heat dissipation member 20 is less likely to be hindered by the voids V1. Accordingly, the thermal conductivity between the ceramic phosphor 10 and the heat dissipation member 20 can be improved. In addition, in the wavelength conversion member 1 according to the present embodiment, the overflow portion 32 is separated from the side surface 14 of the ceramic phosphor 10. When the temperature is lowered after the ceramic phosphor 10 and the heat dissipation member 20 are joined, even if shrinkage occurs, the ceramic phosphor 10 is not restricted. Thus, breakage of the ceramic phosphor 10 due to shrinkage of the solder layer 30 can be suppressed. In this way, it is possible to achieve both improvement of the thermal conductivity between the ceramic phosphor 10 and the heat dissipation member 20 and suppression of breakage of the ceramic phosphor 10. In addition, since the thermal conductivity between the ceramic phosphor 10 and the heat dissipation member 20 is improved, the durability of the ceramic phosphor 10 is improved, and a decrease in luminous efficiency can be suppressed.

[0064] In addition, in the wavelength conversion member 1 according to the present embodiment, the porosity of the joint portion 31 is smaller than the porosity of the overflow portion 32. Thus, heat conduction between the ceramic phosphor 10 and the heat dissipation member 20 through the joint portion 31 is less likely to be hindered by the voids V1. Accordingly, the thermal conductivity between the ceramic phosphor 10 and the heat dissipation member 20 can be improved.

[0065] In addition, in the wavelength conversion member 1 according to the present embodiment, in the joint portion 31, the porosity of the central portion 31a between the portion C10 at the center of the ceramic phosphor 10 and the heat dissipation member 20 is smaller than the porosity of the other portion 31b of the joint portion 31. The central portion 31a of the joint portion 31 is located between the portion C10 at the center of the ceramic phosphor 10, which is likely to generate more heat due to being easily irradiated with light, and the heat dissipation member 20. Thus, the central portion 31a of the joint portion 31 has better thermal conductivity in the joint portion 31. Therefore, heat generated in the portion C10 at the center of the ceramic phosphor 10 due to the irradiated light can be quickly transferred to the heat dissipation member 20. Accordingly, by making the porosity of the central portion 31a smaller than the porosity of the other portion 31b of the joint portion 31, the thermal conductivity between the ceramic phosphor 10 and the heat dissipation member 20 can be improved.

[0066] In addition, in the wavelength conversion member 1 according to the present embodiment, the overflow portion 32 is formed to surround the outer peripheral portion 13 of the ceramic phosphor 10 over the entire circumference. Thus, when the ceramic phosphor 10 and the heat dissipation member 20 are joined, the solder in the central portion S41 of the solder layer 30 overflows over the entire circumference of the outer peripheral portion 13 of the ceramic phosphor 10. Compared with the case where the overflow portion 32 is formed to surround a part of the outer peripheral portion 13 of the ceramic phosphor 10, the distance by which the void V1 in the central portion S41 moves to the outer portion S42 is shorter, and thus the number of voids V1 in the joint portion 31 is further reduced. Therefore, the thermal conductivity between the ceramic phosphor 10 and the heat dissipation member 20 can be further improved.

[0067] In addition, in the wavelength conversion member 1 according to the present embodiment, the height H1, which is the maximum value of the thickness of the overflow portion 32, is two times or more and ten times or less the average value of the thickness of the joint portion 31. Thus, the void V1 that moves from between the ceramic phosphor 10 and the heat dissipation member 20 to the outside of the outer peripheral portion 13 of the ceramic phosphor 10 easily floats in the solder layer 30 outside the outer peripheral portion 13 of the ceramic phosphor 10. Thus, the void V1 in the central portion S41 easily moves to the outer portion S42, and therefore the number of voids V1 in the joint portion 31 is further reduced. Therefore, the thermal conductivity between the ceramic phosphor 10 and the heat dissipation member 20 can be further improved.

[0068] In addition, in the wavelength conversion member 1 according to the present embodiment, the height H1 of the overflow portion 32 measured from the heat dissipation member 20 is lower than the height H2 of the light incident surface 11 of the ceramic phosphor 10 for light incident measured from the heat dissipation member 20. Thus, it is possible to suppress light emitted from the ceramic phosphor 10 from being blocked by the overflow portion 32 whose maximum thickness is greater than the average value of the thickness of the joint portion 31.

[0069] In addition, in the light source device 5 according to the present embodiment, the light source device 5 emits light L2 having a wavelength different from the wavelength of the light L1 irradiated by the light source 6 to the ceramic phosphor 10 to the outside. In the wavelength conversion member 1 including the ceramic phosphor 10 that converts the wavelength of the light L1, since the number of voids V1 included in the joint portion 31 of the solder layer 30 between the ceramic phosphor 10 and the heat dissipation member 20 is relatively small, heat conduction between the ceramic phosphor 10 and the heat dissipation member 20 at the joint portion 31 is not easily blocked by the voids V1. Thus, it is possible to suppress a decrease in the light emission intensity of the light source device 5 due to temperature quenching. Since the overflow portion 32 is separated from the side surface 14 of the ceramic phosphor 10, it is possible to suppress breakage of the ceramic phosphor 10 due to shrinkage of the solder layer 30. Thus, it is possible to suppress a decrease in the light emission intensity of the light source device 5 due to breakage of the ceramic phosphor 10.

[0070] <Modifications of the present embodiment>

[0071] The present invention is not limited to the above-described embodiments and can be implemented in various ways without departing from its gist. For example, it can be modified as follows.

[0072] [Modification Example 1]

[0073] In the solder layer 30 of the above-described embodiment, the porosity of the overflow portion 32 that is separated from the side surface 14 of the ceramic phosphor 10 and has a maximum thickness greater than the average thickness of the joint portion 31 is greater than the porosity of the joint portion 31, and the porosity of the central portion 31a is less than the porosity of the other portion 31b. However, the shape and porosity characteristics of the solder layer 30 are not limited to this. It may also be that the porosity of the overflow portion 32 that is separated from the side surface 14 of the ceramic phosphor 10 and has a maximum thickness greater than the average thickness of the joint portion 31 is greater than the porosity of the joint portion 31, but the porosity of the central portion 31a is greater than the porosity of the other portion 31b.

[0074] [Modification Example 2]

[0075] In addition, in the solder layer 30, it may be only that the porosity of the overflow portion 32 is greater than the porosity of the joint portion 31, the maximum thickness of the overflow portion 32 may be of the same degree as or less than the average thickness of the joint portion 31, and the porosity of the central portion 31a may also be greater than the porosity of the other portion 31b.

[0076] Figure 8 It is a cross-sectional view of a modification example of the wavelength conversion member 1 of the first embodiment. Figure 8 The shown modification example of the wavelength conversion member 1 is obtained by Figure 8 processing the overflow portion 32 as a processing step for the wavelength conversion member 1 manufactured by the manufacturing method described in the first embodiment shown in (a). Specifically, as Figure 8 shown in (b), the portion 32a that forms the inner wall 33 in the overflow portion 32 is removed. For example, the thickness of the remaining portion 32b of the overflow portion 32 is made to be of the same degree as the thickness of the joint portion 31. Even for Figure 8 the wavelength conversion member 1 having the shape shown in (b), when the ceramic phosphor 10 and the heat dissipation member 20 are joined, the void V1 moves to the outside of the ceramic phosphor 10. Therefore, the porosity of the joint portion 31 is less than the porosity of the overflow portion 32. Thus, even for Figure 8In the wavelength conversion member 1 in the state as shown, heat transfer between the ceramic phosphor 10 and the heat dissipation member 20 is not easily hindered by the void V1, so the thermal conductivity between the ceramic phosphor 10 and the heat dissipation member 20 can be improved. In addition, as long as a part of the overflow portion 32 removed in the processing step includes the portion 32a that forms the inner wall 33 separated from the side surface 14 of the ceramic phosphor 10, the thickness of the remaining portion 32b after processing can also be thinner than the thickness of the joint portion 31.

[0077] [Modification Example 3]

[0078] In addition, in the solder layer 30, it is only necessary that the porosity of the central portion 31a is smaller than the porosity of the other portions 31b. The maximum value of the thickness of the overflow portion 32 can also be smaller than the average value of the thickness of the joint portion 31, and the porosity of the overflow portion 32 can also be smaller than the porosity of the joint portion 31.

[0079] [Modification Example 4]

[0080] In the above-described embodiment, the overflow portion 32 is formed to surround the outer peripheral portion 13 of the ceramic phosphor 10 over the entire circumference. However, the overflow portion 32 can also be formed adjacent to a part of the outer peripheral portion 13 of the ceramic phosphor 10.

[0081] Figure 9 It is a top view of another modification of the wavelength conversion member 1 of the first embodiment. As Figure 9 shown, the overflow portion 32 can also be formed in a C shape, for example, so as to surround a part of the outer peripheral portion 13 of the ceramic phosphor 10. Specifically, the overflow portion 32 can be formed so as to surround the outer peripheral portion 13 of the side surfaces 14b, 14c, and 14d among the four side surfaces 14a, 14b, 14c, and 14d of the ceramic phosphor 10 formed in a rectangular shape. Even in such a case, when the ceramic phosphor 10 and the heat dissipation member 20 are joined, the void between the ceramic phosphor 10 and the heat dissipation member 20 moves to the outside of the ceramic phosphor 10, so the thermal conductivity between the ceramic phosphor 10 and the heat dissipation member 20 can be improved.

[0082] [Modification Example 5]

[0083] In the above-described embodiment, the maximum value of the thickness of the overflow portion 32 is more than twice and less than ten times the average value of the thickness of the joint portion 31. However, the relationship between the maximum value of the thickness of the overflow portion 32 and the average value of the thickness of the joint portion 31 is not limited to this. Even if the maximum value of the thickness of the overflow portion 32 is less than twice the average value of the thickness of the joint portion 31, the void V1 in the central portion S41 of the solder layer 30 moves to the outer portion S42, so the thermal conductivity between the ceramic phosphor 10 and the heat dissipation member 20 can be improved.

[0084] [Modification Example 6]

[0085] In the above-described embodiment, the height H1 of the vertex 34 of the overflow portion 32 measured from the heat dissipation member 20 is lower than the height H2 of the ceramic phosphor 10 measured from the heat dissipation member 20. However, the relationship between the height H1 of the overflow portion 32 and the height H2 of the ceramic phosphor 10 is not limited to this.

[0086] [Modification Example 7]

[0087] In the above-described embodiment, the void V1 is caused by the gap between the metal film and the Au—Sn solder foil F1, the gap between the bonding film and the Au—Sn solder foil F1, and the gas mixed in during the plating process. However, the cause of the generation of the void V1 is not limited to this, and it may also be caused by the binder contained in the Au—Sn paste when the Au—Sn paste is used.

[0088] As described above, the present solution has been described based on the embodiments and modification examples. However, the embodiments of the above solution are provided for easy understanding of the present solution, rather than limiting the present solution. The present solution can be changed and improved without departing from its gist and the claims, and the present solution includes its equivalents. In addition, if its technical features are not described as essential features in this specification, they can be appropriately deleted.

[0089] Explanation of Reference Numerals

[0090] 1, wavelength conversion member; 5, light source device; 6, light source; 10, ceramic phosphor; 11, incident surface; 12, main surface; 13, outer peripheral portion; 14, 14a, 14b, 14c, 14d, side surface; 20, heat dissipation member; 21, main surface; 30, solder layer; 31, joint portion; 31a, central portion; 31b, other portion; 32, overflow portion; 32a, separated portion; 32b, remaining portion; 33, inner wall; 34, vertex; 40, molten solder; C10, central portion of ceramic phosphor; F1, Au—Sn solder foil; L1, L2, light; S41, central portion; S42, outer portion; S43, inner wall; V1, void.

Claims

1. A wavelength conversion member, wherein, the wavelength conversion member includes: a ceramic phosphor that converts the wavelength of incident light; a heat dissipation member that releases the heat of the ceramic phosphor to the outside; and a solder layer that joins the ceramic phosphor and the heat dissipation member, the solder layer includes a joint portion disposed between the ceramic phosphor and the heat dissipation member, and an overflow portion that overflows outward from the outer peripheral portion of the ceramic phosphor, the overflow portion is formed so as to surround the outer peripheral portion of the ceramic phosphor and is separated from the side surface formed on the outer peripheral portion of the ceramic phosphor, the maximum value of the thickness of the overflow portion is more than twice and less than 10 times the average value of the thickness of the joint portion, in the solder layer, the maximum value of the thickness of the overflow portion is greater than the average value of the thickness of the joint portion, the overflow portion is formed by extruding the solder between the ceramic phosphor and the heat dissipation member to the outside of the outer peripheral portion of the ceramic phosphor when a load is applied to the ceramic phosphor and the heat dissipation member to join the ceramic phosphor and the heat dissipation member.

2. A wavelength conversion member, wherein, the wavelength conversion member includes: a ceramic phosphor that converts the wavelength of incident light; a heat dissipation member that releases the heat of the ceramic phosphor to the outside; and a solder layer that joins the ceramic phosphor and the heat dissipation member, the solder layer includes a joint portion disposed between the ceramic phosphor and the heat dissipation member, and an overflow portion that overflows outward from the outer peripheral portion of the ceramic phosphor, the porosity of the joint portion is less than the porosity of the overflow portion, the overflow portion is formed so as to surround the outer peripheral portion of the ceramic phosphor and is separated from the side surface formed on the outer peripheral portion of the ceramic phosphor, in the solder layer, the maximum value of the thickness of the overflow portion is greater than the average value of the thickness of the joint portion, the overflow portion is formed by extruding the solder between the ceramic phosphor and the heat dissipation member to the outside of the outer peripheral portion of the ceramic phosphor when a load is applied to the ceramic phosphor and the heat dissipation member to join the ceramic phosphor and the heat dissipation member.

3. A wavelength conversion member, wherein, the wavelength conversion member includes: a ceramic phosphor that converts the wavelength of incident light; a heat dissipation member that releases the heat of the ceramic phosphor to the outside; and a solder layer that joins the ceramic phosphor and the heat dissipation member, the solder layer includes a joint portion disposed between the ceramic phosphor and the heat dissipation member, and an overflow portion that overflows outward from the outer peripheral portion of the ceramic phosphor, the porosity of the central portion of the joint portion through which the central axis of the wavelength conversion member passes is less than the porosity of the other portions of the joint portion except the central portion, the overflow portion is formed so as to surround the outer peripheral portion of the ceramic phosphor and is separated from the side surface formed on the outer peripheral portion of the ceramic phosphor, in the solder layer, the maximum value of the thickness of the overflow portion is greater than the average value of the thickness of the joint portion, The overflow portion is formed by extruding the solder between the ceramic phosphor and the heat sink member to the outside of the outer peripheral portion of the ceramic phosphor when a load is applied to the ceramic phosphor and the heat sink member to join the ceramic phosphor and the heat sink member.

4. The wavelength conversion member according to claim 2 or 3, wherein The maximum value of the thickness of the overflow portion is more than twice and less than 10 times the average value of the thickness of the joint portion.

5. The wavelength conversion member according to any one of claims 1 to 3, wherein The overflow portion is formed to surround the outer peripheral portion of the ceramic phosphor over the entire circumference.

6. The wavelength conversion member according to any one of claims 1 to 3, wherein The height of the overflow portion measured from the heat sink member is lower than the height of the light incident surface of the ceramic phosphor for light incidence measured from the heat sink member.

7. A light source device, wherein The light source device includes: The wavelength conversion member according to any one of claims 1 to 6; and A light source that irradiates light to the ceramic phosphor.

8. A method for manufacturing a wavelength conversion member, wherein The method for manufacturing the wavelength conversion member includes: A preparation step in which a ceramic phosphor that converts the wavelength of incident light and a heat sink member to be joined to the ceramic phosphor are prepared; A joining step in which the ceramic phosphor and the heat sink member are joined using a solder layer; And A processing step in which, after the joining step, the solder layer is processed by this processing step. In the joining step, the solder layer forms a joint portion and an overflow portion. The joint portion is disposed between the ceramic phosphor and the heat sink member. The overflow portion is formed by extruding the solder between the ceramic phosphor and the heat sink member to the outside of the outer peripheral portion of the ceramic phosphor when a load is applied to the ceramic phosphor and the heat sink member to join the ceramic phosphor and the heat sink member. The maximum value of the thickness of the overflow portion is greater than the average value of the thickness of the joint portion, and the overflow portion surrounds the outer peripheral portion of the ceramic phosphor. In the processing step, at least a part of the overflow portion, including a part separated from the side surface formed on the outer peripheral portion of the ceramic phosphor, is removed. In the wavelength conversion member manufactured by the method for manufacturing the wavelength conversion member, the overflow portion is separated from the side surface formed on the outer peripheral portion of the ceramic phosphor, and the maximum value of the thickness of the overflow portion is more than twice and less than 10 times the average value of the thickness of the joint portion.

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