CN203857299U - Light emitting device and illuminating device - Google Patents

Abstract

The utility model provides a light emitting device and an illuminating device which have high reliability. According to the embodiment, the illuminating device is provided and comprises a base part, a plurality of semiconductor light emitting components, a mounting substrate part, a metal plate, a jointing layer, a grease layer and a fixing part. The plurality of semiconductor light emitting components are separated from the base part. The installation substrate part comprises ceramic substrates arranged between the base part and the plurality of semiconductor light emitting components. The metal plate is arranged between the base part and the installation substrate part. The metal plate is provided with an outer edge part and an inside part inside the outer edge part. The ratio of the thickness of the metal plate to the maximum length of the inside part is over 0.042. The jointing layer is arranged between the installation substrate part and the metal plate and is used for jointing the installation substrate part with the metal plate. The grease layer is arranged between the base part and the metal plate. The fixing part is used for fixing the outer edge part of the metal plate and the base part.

Description

Lighting device and lighting device

technical field

Embodiments of the present invention relate to a light emitting device and a lighting device. the

Background technique

For example, there is a light-emitting device that emits white light by combining a semiconductor light-emitting element that emits blue light and a phosphor that converts the wavelength of light. Such a light emitting device can be applied to lighting devices such as light projectors and the like. In such a light-emitting device, it is desired to improve reliability. the

Patent Document 1: JP Unexamined Patent Publication No. 8-8372

Contents of the invention

The embodiments of the present invention provide a highly reliable light emitting device and lighting device. the

According to an embodiment of the present invention, there is provided a lighting device including a base member, a plurality of semiconductor light emitting elements, a mounting board portion, a metal plate, a bonding layer, a grease layer, and a fixing portion. The plurality of semiconductor light emitting elements are separated from the base member. The mounting substrate portion includes a ceramic substrate provided between the base member and the plurality of semiconductor light emitting elements. The metal plate is provided between the base member and the mounting board portion. The metal plate has an outer edge portion and an inner portion inside the outer edge portion. A ratio of the thickness of the metal plate to the maximum length of the inner portion is 0.042 or more. The joining layer is provided between the mounting board part and the metal plate, and joins the mounting board part and the metal plate. The grease layer is provided between the base member and the metal plate. The fixing portion fixes the outer edge portion of the metal plate and the base member. the

According to an embodiment of the present invention, there is provided a light-emitting device that is fixed to the base member through a fixing portion with a grease layer interposed therebetween, the light-emitting device comprising: a mounting substrate portion including a ceramic substrate; A plurality of semiconductor light-emitting elements are provided on one side of the mounting substrate part; a metal plate is provided on the other side of the mounting substrate part and the other side is thermally conductive to the base member via the grease layer. connected, the metal plate has an outer edge portion as a region fixed by the fixing portion and an inner portion inside the outer edge portion, the ratio of the thickness of the metal plate to the maximum length of the inner portion is 0.042 or more; and a bonding layer provided between the mounting substrate portion and the metal plate, and bonding the mounting substrate portion and the metal plate. the

Compared with the prior art, the light emitting device and the lighting device provided by the utility model have higher reliability. the

Description of drawings

1a and 1b are schematic diagrams illustrating a light emitting device and a lighting device in the first embodiment. the

2a and 2b are schematic diagrams illustrating the light emitting device and the lighting device in the first embodiment. the

FIG. 3 is a schematic diagram illustrating characteristics of a light emitting device and a lighting device. the

Fig. 4 is a graph illustrating characteristics of a light emitting device and a lighting device. the

Fig. 5 is a graph illustrating characteristics of a light emitting device and a lighting device. the

FIG. 6 is a schematic cross-sectional view illustrating the light emitting device in the first embodiment. the

7 is a schematic plan view illustrating a light emitting device and an illuminating device in the first embodiment. the

8a and 8b are schematic diagrams illustrating the light emitting device and the lighting device in the first embodiment. the

Fig. 9 is a schematic plan view illustrating the light emitting device and the lighting device in the first embodiment. the

Fig. 10 is a schematic cross-sectional view illustrating a light emitting device and a lighting device in a second embodiment. the

In the picture:

10: ceramic substrate; 10a: first main surface; 10b: second main surface; 10r: outer edge; 11: first metal layer; 11a: first installation part; 11b: second installation part; 11c: third installation Part; 11g: position; 11p: installation pattern; 11pa: first installation pattern; 11pb: second installation pattern; 11s: side; 11su: corner; 11u: upper surface; 12: second metal layer; 12c: corner ;12r: outer edge; 13a: copper layer; 13b: nickel layer; 13c: palladium layer; 13d: gold layer; 14a: copper layer; 14b: nickel layer; 14c: palladium layer; 14d: gold layer; 15: mounting substrate 16: installation area; 16r: outer edge; 17: peripheral area; 20: semiconductor light emitting element; 20a: first semiconductor light emitting element; 20b: second semiconductor light emitting element; 21: first semiconductor layer; 21a: first Semiconductor part; 21b: second semiconductor part; 21e: first bonding metal part; 22: second semiconductor layer; 22e: second bonding metal part; 23: light emitting layer; 31: wavelength converting layer; 31a: wavelength converting particles; 31b: Translucent resin; 32: Reflective layer; 35: Light emitting element part; 40: Light emitting part; 40a: First light emitting part; 40b: Second light emitting part; 44: Connection part; 45: First connector; 45e : first connector electrode part; 46: second connector; 46e: second connector electrode part; 51: metal plate; 51i: inner part; 51o: outer edge part; 51r: edge part; 52: joining layer; 53: Grease layer; 53r: Heat dissipation paste residual part; 53s: Heat dissipation paste disappearance part; 55a~55d: 1st~4th side; 58: Hole; 71: Base part; 72: Base; 73: Reflection part; 75: Fixed part; θ: Angle; 110, 121: Lighting device; 210, 221: Lighting device; C51: Warpage; L01, L02: 1st, 2nd length; LL: Light; Lmax: Maximum length; RA : residual area ratio of thermal paste; RC1: relative warpage; RT1: relative thickness; SP1: sample; t10, t11, t12, t20, t51: thickness; tg: distance. the

Detailed ways

Embodiments of the present invention will be described below with reference to the drawings. the

In addition, the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, and the like are not necessarily the same as those in reality. In addition, even if the same parts are shown, they may be shown with different dimensions and ratios in different drawings. the

In addition, in this-application specification and each drawing, the same code|symbol is attached|subjected to the same element as what was already described by drawing, and detailed description is abbreviate|omitted suitably. the

(first embodiment)

1a and 1b are schematic diagrams illustrating a light emitting device and a lighting device in the first embodiment. the

Figure 1a is a top view. Fig. 1b is a cross-sectional view illustrating a part of the cross-section along line A1-A2 in Fig. 1a. the

As shown in FIGS. 1a and 1b , a light emitting device 110 in this embodiment includes a base member 71 , a grease layer 53 , a metal plate 51 , a bonding layer 52 , a mounting substrate portion 15 , and a plurality of semiconductor light emitting elements 20 . The light emitting device 110 is used, for example, as a lighting device 210 . the

Let the direction from the base member 71 toward the mounting substrate portion 15 be the stacking direction (Z-axis direction). Let one direction perpendicular to the Z-axis direction be the X-axis direction. Let the direction perpendicular to the Z-axis direction and the X-axis direction be the Y-axis direction. the

On the base member 71, the grease layer 53, the metal plate 51, the bonding layer 52, the mounting substrate portion 15, and the plurality of semiconductor light emitting elements 20 are sequentially arranged. the

That is, the plurality of semiconductor light emitting elements 20 are separated from the base member 71 in the Z-axis direction. The mounting substrate portion 15 includes the ceramic substrate 10 . The ceramic substrate 10 is provided between the base member 71 and the plurality of semiconductor light emitting elements. The metal plate 51 is provided between the base member 71 and the mounting substrate portion 15 . the

As illustrated in FIG. 1a, the metal plate 51 has an outer edge portion 51o and an inner portion 51i. The inner portion 51i is located inside the outer edge portion 51o. When the metal plate 51 is projected on the XY plane, the outer edge portion 51 o is provided along the outer edge 51 r of the metal plate 51 . When the metal plate 51 is projected on the XY plane, the inside part 51i is located inside the outer edge part 51o. Examples of the outer edge portion 51o and the inner portion 51i will be described later. the

As illustrated in FIG. 1 b , the bonding layer 52 is provided between the mounting substrate portion 15 and the metal plate 51 . The bonding layer 52 bonds the mounting substrate portion 15 and the metal plate 51 . the

The grease layer 53 is provided between the base member 71 and the metal plate 51 . The grease layer 53 transfers the heat of the metal plate 51 to the base member 71 . the

The fixing portion 75 fixes the outer edge portion 51 o of the metal plate 51 and the base member 71 . In this example, the metal plate 51 has a hole 58 (for example, a through hole) provided in the outer edge portion 51o. Screws are used for the fixing portion 75 . The screws reach the base part 71 via the holes 58 . That is, a part of the fixing portion 75 passes through the hole 58 . Thereby, the outer edge part 51o of the metal plate 51 and the base member 71 are fixed. In addition, the inner side portion 51 i of the metal plate 51 is not fixed to the base member 71 . the

Hereinafter, an example of the light emitting device 110 (and the lighting device 210 ) shown in FIGS. 1 a and 1 b will be described. the

The light emitting unit 40 is provided in the light emitting device 110 . The light emitting unit 40 is provided on the metal plate 51 . A bonding layer 52 is provided between the metal plate 51 and the light emitting portion 40 . the

In the specification of the present application, the state provided thereon includes not only the state provided directly thereon, but also the state in which other elements are inserted therebetween. the

The direction from the metal plate 51 toward the light emitting portion 40 corresponds to the stacking direction. In the specification of this application, the state of stacking includes not only the state of overlapping with direct contact, but also the state of overlapping with other elements interposed therebetween. the

The metal plate 51 is, for example, plate-shaped. The main surface of the metal plate 51 is substantially parallel to the XY plane, for example. The planar shape of the metal plate 51 is, for example, a rectangle. The metal plate 51 has, for example, first to fourth sides 55a to 55d. The second side 55b is separated from the first side 55a. The third side 55c connects one end of the first side 55a and one end of the second side 55b. The fourth side 55d is separated from the third side 55c, and connects the other end of the first side 55a and the other end of the second side 55b. The corners of the planar shape of the metal plate 51 may be curved. The planar shape of the metal plate 51 may be arbitrary instead of rectangular. the

For the metal plate 51, a substrate such as metal can be used, for example. For the metal plate 51, copper, copper alloy, or aluminum can be used, for example. the

The light emitting unit 40 emits light. At the same time, the light emitting unit 40 generates heat. The bonding layer 52 efficiently conducts the heat generated in the light emitting portion 40 to the metal plate 51 . For the bonding layer 52 , for example, solder or the like can be used. That is, the bonding layer 52 contains solder. For the bonding layer 52 , for example, a solder material mainly composed of Sn can be used. For the bonding layer 52 , for example, SnAg, SnCu, SnAgCu, SnSb, SnBi, or SnZn can be used. the

The light emitting unit 40 includes the mounting board unit 15 and the light emitting element unit 35 . the

Mounting substrate portion 15 includes ceramic substrate 10 , first metal layer 11 , and second metal layer 12 . the

The ceramic substrate 10 has a first main surface 10a and a second main surface 10b. The second main surface 10b is a surface on the opposite side to the first main surface 10a. The metal plate 51 faces the second main surface of the ceramic substrate 10 . In other words, the second main surface 10 b is a surface on the metal plate 51 side. That is, the second main surface 10 b is a surface on the bonding layer 52 side. the

In the specification of the present application, the state of facing each other includes not only the state of directly facing each other, but also the state of interposing other elements therebetween. the

The first main surface 10 a includes a mounting region 16 . For example, the mounting region 16 is separated from the outer edge 10r of the first main surface 10a. In this example, the mounting region 16 is provided in the central portion of the first main surface 10a. The first main surface 10 a also includes a peripheral region 17 . The peripheral area 17 is provided around the installation area 16 . An example of the installation area 16 will be described later. the

The ceramic substrate 10 contains, for example, alumina. For the ceramic substrate 10 , for example, ceramics mainly composed of alumina can be used. High thermal conductivity and high insulation can be obtained. High reliability can be obtained. the

The first metal layer 11 is provided on the first main surface 10a. The first metal layer 11 includes a plurality of mounting patterns 11p. A plurality of mounting patterns 11 p are provided in the mounting area 16 . At least any two or more of the plurality of mounting patterns 11p are separated from each other. For example, at least any one of the plurality of mounting patterns 11p has an island shape. Two of the plurality of mounting patterns 11p are independent from each other. The plurality of mounting patterns 11p include, for example, a first mounting pattern 11pa, a second mounting pattern 11pb, and the like. the

Each of the plurality of mounting patterns 11p includes, for example, the first mounting portion 11a and the second mounting portion 11b. In this example, the mounting pattern 11p also includes the third mounting portion 11c. The 3rd mounting part 11c is provided between the 1st mounting part 11a and the 2nd mounting part 11b, and connects the 1st mounting part 11a and the 2nd mounting part 11b. Examples of these installation parts will be described later. the

The first metal layer 11 may further include connection portions 44 that connect the plurality of mounting patterns 11p to each other. In this example, the first metal layer 11 further includes a first connector electrode portion 45e and a second connector electrode portion 46e. The first electrode portion 45e for a connector is electrically connected to one of the plurality of mounting patterns 11p. The second electrode portion 46e for a connector is electrically connected to another one of the plurality of mounting patterns 11p that is different from the one described above. For example, the semiconductor light emitting element 20 is arranged on a part of one mounting pattern 11p. With this semiconductor light emitting element 20, the first connector electrode portion 45e is electrically connected to one of the mounting patterns 11p. Furthermore, the semiconductor light emitting element 20 is arranged on a part of another mounting pattern 11p. Through this semiconductor light emitting element 20, the second connector electrode portion 46e is electrically connected to one of the other mounting patterns 11p. the

In this example, the light emitting unit 40 further includes a first connector 45 and a second connector 46 provided on the first main surface 10a. The first connector 45 is electrically connected to the first connector electrode portion 45e. The second connector 46 is electrically connected to the second connector electrode portion 46e. In this example, the first connector 45 is provided on the first connector electrode portion 45e. The 2nd connector 46 is provided in the electrode part 46e for 2nd connectors. The light emitting element unit 35 is arranged between the first connector 45 and the second connector 46 . Power is supplied to the light emitting unit 40 via these connectors. the

The second metal layer 12 is provided on the second main surface 10b. The second metal layer 12 is electrically insulated from the first metal layer 11 . At least a part of the second metal layer 12 overlaps the mounting region 16 when projected onto the XY plane (first plane parallel to the first main surface 10 a ). the

Thus, the first metal layer 11 is provided on the upper surface (first main surface 10 a ) of the ceramic substrate 10 , and the second metal layer 12 is provided on the lower surface (second main surface 10 b ) of the ceramic substrate 10 . the

The light emitting element portion 35 is provided on the first main surface 10 a of the ceramic substrate 10 . The light emitting element unit 35 includes a plurality of semiconductor light emitting elements 20 and a wavelength conversion layer 31 . the

A plurality of semiconductor light emitting elements 20 are provided on the first main surface 10a. The plurality of semiconductor light emitting elements 20 emit light respectively. The semiconductor light emitting element 20 includes, for example, a nitride semiconductor. The semiconductor light emitting element 20 includes, for example, In _y Al _z Ga _1-x-y N (0≤x≤1, 0≤y≤1, x+y≤1). However, in the embodiment, the semiconductor light emitting element 20 is arbitrary.

The plurality of semiconductor light emitting elements 20 include, for example, a first semiconductor light emitting element 20a, a second semiconductor light emitting element 20b, and the like. The plurality of semiconductor light emitting elements 20 are respectively electrically connected to any one of the plurality of mounting patterns 11p and another mounting pattern 11p adjacent to any one of the plurality of mounting patterns 11p. the

For example, the first semiconductor light emitting element 20a is electrically connected to the first mounting pattern 11pa and the second mounting pattern 11pb among the plurality of mounting patterns 11p. The second mounting pattern 11pb corresponds to another mounting pattern 11p adjacent to the first mounting pattern 11pa. the

For example, each of the plurality of semiconductor light emitting elements 20 includes a first semiconductor layer 21 of the first conductivity type, a second semiconductor layer 22 of the second conductivity type, and a light emitting layer 23 . For example, the first conductivity type is n-type, and the second conductivity type is p-type. The first conductivity type may be p-type, and the second conductivity type may be n-type. the

The first semiconductor layer 21 includes a first portion (first semiconductor portion 21a) and a second portion (second semiconductor portion 21b). The second semiconductor portion 21b is juxtaposed with the first semiconductor portion 21a in a direction (for example, the X-axis direction) intersecting the stacking direction (the Z-axis direction from the metal plate 51 toward the light emitting portion 40). the

The second semiconductor layer 22 is provided between the second semiconductor portion 21 b and the mounting substrate portion 15 . The light emitting layer 23 is provided between the second semiconductor portion 21 b and the second semiconductor layer 22 . the

The semiconductor light emitting element 20 is, for example, a flip-chip LED. the

For example, the first semiconductor portion 21a of the first semiconductor layer 21 faces the first mounting portion 11a of the mounting pattern 11p. The second semiconductor layer 22 faces the second mounting portion 11b of the mounting pattern 11p. The first semiconductor portion 21a of the first semiconductor layer 21 is electrically connected to the first mounting portion 11a. The second semiconductor layer 22 is electrically connected to the second mounting portion 11b. The connection may use, for example, solder, gold bumps, or the like. The connection can be made, for example, by metal fusion welding. Alternatively, the connection is performed by, for example, ultrasonic thermocompression bonding using gold bumps. the

That is, for example, the light emitting element portion 35 further includes the first joining metal member 21e and the second joining metal member 22e. The first bonding metal member 21e is provided between the first semiconductor portion 21a and any one of the mounting patterns 11p (for example, the first mounting portion 11a). The second bonding metal member 22e is provided between the second semiconductor layer 22 and another mounting pattern 11p (for example, the second mounting pattern 11pb). At least one of the first joint metal member 21e and the second joint metal member 22e includes solder or a gold bump. Thereby, the cross-sectional area (the cross-sectional area when cut along the XY plane) of each of the first metal joining member 21e and the second metal joining member 22e can be increased. Thereby, heat can be efficiently transmitted to the mounting board part 15 through the 1st metal joining member 21e and the 2nd metal joining member 22e, and heat dissipation improves. the

The wavelength conversion layer 31 covers at least a part of the plurality of semiconductor light emitting elements 20 . The wavelength conversion layer 31 absorbs at least part of the light (for example, first light) emitted from the plurality of semiconductor light emitting elements 20 and emits second light. The wavelength (for example, peak wavelength) of the second light is different from the wavelength (for example, peak wavelength) of the first light. The wavelength conversion layer 31 includes, for example, a plurality of wavelength conversion particles such as phosphors, and a translucent resin in which the plurality of wavelength conversion particles are dispersed. The first light includes, for example, blue light. The second light includes light having a longer wavelength than the first light. The second light includes, for example, at least one of yellow light and red light. the

In this example, the light emitting element portion 35 further includes the reflective layer 32 . The reflective layer 32 surrounds the wavelength conversion layer 31 in the XY plane. Reflective layer 32 includes, for example, a plurality of particles of metal oxide and a translucent resin in which the particles are dispersed. Particles such as metal oxides have light reflectivity. At least any one of TiO ₂ and Al ₂ O ₃ can be used as the particles of the metal oxide or the like, for example. By providing the reflective layer 32, the light emitted from the semiconductor light emitting element 20 can be efficiently emitted in a direction (for example, an upward direction) along the stacking direction.

The light emitting unit 40 is, for example, a chip-on-board (COB) type LED module. the

In the present embodiment, the luminosity of light emitted from the light emitting element portion 35 (the plurality of semiconductor light emitting elements 20 ) is 10 lm/mm ² (lumen/square millimeter) or more and 100 lm/mm ² or less. Preferably it is 20 lm/mm ² or more. That is, in the present embodiment, the ratio (luminosity) of the light emitted from the light emitting element portion 35 to the light emitting area is very high. In the specification of the present application, the light emitting area substantially corresponds to the area of the mounting region 16 .

The light emitting device 110 in this embodiment can be applied to an illumination device 210 such as a light projector, for example. the

For the grease layer 53 , liquid, paste, clay, or solid thermal paste can be used. As the thermal paste, for example, silicone oil can be used. For example, at least one of metal particles and ceramic particles is mixed with silicone oil. Accordingly, the thermal conductivity of the silicone oil increases. For the grease layer 53 , for example, conductive heat dissipation paste (conductive heat dissipation paste) or the like may be used. This conductive heat dissipation paste contains, for example, silicon with pure metal particles having high thermal conductivity. For example, the heat of the light emitting element portion 35 is conducted to the base member 71 through the grease layer 53 to dissipate heat. the

In the light emitting device 110 according to the present embodiment, for example, when the metal plate 51 is projected on the XY plane, the metal plate 51 has an area five times or more the area of the mounting region 16 . That is, in the present embodiment, the area of the metal plate 51 is set to be very large relative to the area of the mounting region 16 . Accordingly, the heat generated by the light emitting element portion 35 provided on the mounting region 16 is diffused in the in-plane direction (XY in-plane direction) through the metal plate 51 having a large area. Furthermore, the heat diffused in the in-plane direction is transferred to, for example, the base member 71 to dissipate heat efficiently. the

2a and 2b are schematic diagrams illustrating the light emitting device and the lighting device in the first embodiment. the

FIG. 2 a is a schematic top view illustrating the metal plate 51 . Fig. 2b is a B1-B2 sectional view of Fig. 2a. the

As illustrated in Fig. 2a, the metal plate 51 has an outer edge portion 51o. The outer edge portion 51 o is provided in a ring shape along the outer edge 51 r of the metal plate 51 . The inner side of the outer edge part 51o is the inner side part 51i. the

In this example, the metal plate 51 has holes 58 . The hole 58 is provided in the outer edge portion 51 o and penetrates through the metal plate 51 . The region where the hole 58 is provided serves as an outer edge portion 51o. The boundary between the outer edge portion 51 o and the inner portion 51 i is in contact with, for example, one end inside the hole 58 . the

For example, the circumscribed rectangle of the inner portion 51 i is in contact with the hole 58 . For example, when projected on the XY plane, the circumscribed rectangle of the inner portion 51i is in contact with the fixing portion 75 . In this example, the inner portion 51i is rectangular. the

In this example, the metal plate 51 has, for example, first to fourth sides 55a to 55d. For example, the first side 55a extends along the X-axis direction. The second side 55b is separated from the first side 55a and extends along the X-axis direction. The third side 55c connects one end of the first side 55a and one end of the second side 55b. The fourth side 55d is separated from the third side 55c, and connects the other end of the first side 55a and the other end of the second side 55b. In this example, the length of the first side 55a and the length of the second side 55b are longer than the length of the third side 55c and the length of the fourth side 55d, respectively. the

In this example, the metal plate 51 has a rectangular shape. For example, the length (1st length L01) of the X-axis direction of the metal plate 51 is 76 mm (millimeters), for example. For example, the length (2nd length L02) of the Y-axis direction of the metal plate 51 is 65 mm, for example. These values are examples, and in the embodiment, these values are arbitrary. The first length L01 may be equal to the second length L02. Curved portions may be provided at corners of the metal plate 51 . The corners can also be inclined with respect to the direction in which the sides extend. the

In the embodiment, the maximum length of the inner portion 51i is set to the maximum length Lmax. The maximum length Lmax is the maximum value of the length in the XY plane of the inner part 51i when the metal plate 51 is projected on the XY plane. In this example, the inner portion 51i is rectangular, and the maximum length Lmax corresponds to the length of the diagonal of the rectangle. The unit of the maximum length Lmax is, for example, millimeters. the

As illustrated in Figure 2b, the metal plate 51 may be bent. For example, the metal plate 51 is bonded to the light emitting unit 40 at high temperature. Due to the difference in thermal expansion coefficient, the metal plate 51 may be bent. the

The degree of warping C51 of the metal plate 51 is the maximum value of the absolute values of the differences between the Z-axis direction position of the end portion of the inner portion 51i and the Z-axis direction position of the center portion of the inner portion 51i of the metal plate 51 . The center part of the inner part 51i is located above the edge part of the inner part 51i. For example, the degree of warpage C51 is the distance in the Z-axis direction between the lower surface of the metal plate 51 at the end of the inner portion 51i and the lower surface of the metal plate 51 at the center of the inner portion 51i. The degree of warpage C51 is the distance in the Z-axis direction between the upper surface of the metal plate 51 at the end of the inner portion 51i and the upper surface of the metal plate 51 at the center of the inner portion 51i. The unit of the degree of warpage C51 is, for example, millimeters. the

On the other hand, the metal plate 51 has a thickness t51. The thickness t51 corresponds to, for example, the length in the Z-axis direction of the metal plate 51 at the central portion of the inner portion 51i. The unit of thickness t51 is millimeters, for example. the

In the embodiment, the maximum length Lmax, the degree of curvature C51, and the thickness t51 are values at room temperature (25° C.). the

In the embodiment, the ratio of the thickness t51 of the metal plate 51 to the maximum length (maximum length Lmax) of the inner portion 51i is set to 0.042 or more. The ratio is t51/Lmax. The outer portion 51 o is pressed by the fixing portion 75 . Substantially no bending occurs in the outer portion 51o. Therefore, the ratio of the thickness t51 of the metal plate 51 to the maximum length (maximum length Lmax) of the inner portion 51i is employed. the

Accordingly, high reliability is obtained in the light emitting device 110 (and the lighting device 210). the

Hereinafter, experimental results serving as a basis for deriving the structure in this embodiment will be described. the

In this experiment, the shape of the metal plate 51 was rectangular, the first length L01 of the metal plate 51 was 76 mm, and the second length L02 of the metal plate 51 was 65 mm. The length of the inner part 51i in the X-axis direction is 59.6 mm, and the length of the inner part 51i in the Y-axis direction is 48.6 mm. The maximum length Lmax (diagonal length of the inner portion 51i ) of the inner portion 51i is 76.9 mm. Then, a plurality of samples in which the thickness t51 of the metal plate 51 was changed were produced, and the degree of warpage C51 of these samples was measured. The metal plate 51 is a copper plate. The ceramic substrate 10 is an alumina substrate. The base member 71 is aluminum or an aluminum alloy. the

In these samples, a reliability test was performed, and the state of the grease layer 53 after the reliability test was evaluated. The reliability test is a temperature cycle test. For example, it is assumed that one cycle is maintained at 120° C. for 30 minutes after holding the sample at −40° C. for 30 minutes. The cycle is repeated to provide the thermal history of the specimen. the

When such a reliability test is performed, the temperature of the sample is repeatedly changed between room temperature and high temperature (for example, about 90° C.). With this change in temperature, the distance between the central portion (inner portion 51i) of the metal plate 51 and the base member 71 changes. Thus, a phenomenon in which the grease layer 53 protrudes to the outside from between the metal plate 51 and the base member 71 can be observed. That is, the material of the grease layer 53 is drawn out. the

Fig. 3 is a schematic diagram illustrating characteristics of a light emitting device and an illumination device. FIG. 3 is a schematic diagram illustrating the state of the grease layer 53 after the reliability test described above. That is, after the reliability test, the fixing portion 75 is removed, and the metal plate 51 is separated from the base member 71 . The state of the exposed grease layer 53 is shown. In the sample SP1 shown in FIG. 3 , the thickness t51 of the metal plate 51 is 5 mm. the

FIG. 3 shows metal plate 51 , hole 58 , grease layer 53 . Before the reliability test, the grease layer 53 is provided on the entire surface of the metal plate 51 . After the reliability test, a part of the thermal paste of the grease layer 53 disappeared due to extraction. Therefore, as shown in FIG. 3 , a heat dissipation paste remaining portion 53r and a heat dissipation paste disappearing portion 53s are generated. In the heat dissipation paste remaining portion 53r, the metal plate 51 is covered with heat dissipation paste. In the heat dissipation paste disappearing portion 53s, the heat dissipation paste disappears and the metal plate 51 is exposed. the

As can be seen from FIG. 3 , in the sample SP1 having a thickness t51 of 5 mm, the area of the heat dissipation paste remaining portion 53 r is large, and the area of the heat dissipation paste disappearing portion 53 s is small. the

If the thermal paste remaining portion 53 r has a small area and the thermal grease disappearing portion 53 s has a large area, it becomes difficult to transfer the heat of the metal plate 51 to the base member 71 . In this state, when the light-emitting device is operated, the temperature of the light-emitting portion rises excessively. For example, luminous efficiency decreases. For example, a component is destroyed. the

Let the area of the thermal paste residual portion 53r be S53r, and let the area of the metal plate 51 be S51. At this time, the thermal paste residual area ratio RA is expressed as S53r/S51. From the results of the reliability test, it was found that good reliability is obtained when the ratio of the area ( S53r ) of the thermal paste remaining portion 53r to the area before the test (corresponding to S51 ) (the residual area ratio of thermal grease RA ) is high. the

It is known that the thermal paste residual area ratio RA depends on the degree of warpage C51. The degree of curvature C51 is a value at room temperature (25° C.). In the reliability test, the temperature of the light-emitting device fluctuated greatly repeatedly. It is considered that the degree of extraction due to this change depends on the degree of warpage C51. In this experiment, when the thickness t51 of the metal plate 51 was 2 mm, the degree of warpage C51 was about 0.44 mm. When the thickness t51 of the metal plate 51 is 3 mm, the curvature C51 is about 0.26 mm. When the thickness t51 of the metal plate 51 is 5 mm, the degree of warpage C51 is about 0.12 mm. the

FIG. 4 is a graph illustrating characteristics of a light emitting device and a lighting device. the

Fig. 4 illustrates the results of the reliability test. The horizontal axis in FIG. 4 is the relative warpage RC1. The relative warpage RC1 is C51/Lmax. The relative degree of curvature RC1 is the ratio of the degree of curvature of the metal plate 51 to the maximum length of the inner portion 51i. The vertical axis of FIG. 4 is the thermal paste residual area ratio RA. the

When the thickness t51 of the metal plate 51 is 2 mm, the thermal paste remaining area ratio RA is about 37%. When the thickness t51 of the metal plate 51 is 3 mm, the thermal paste remaining area ratio RA is about 37%. When the thickness t51 of the metal plate 51 is 5 mm, the heat radiation paste remaining area ratio RA is about 70%. the

As can be seen from FIG. 4 , when the relative warpage RC1 is 0.28% or less, there is a tendency to improve the thermal paste residual area ratio RA. The relative curvature RC1 is preferably 0.23% or less. Thereby, for example, the thermal paste residual area RA becomes 50% or more. When the thermal paste remaining area ratio RA is 50% or more, about half of the heat generated by the light emitting element can be transferred to the metal plate 51 . The relative curvature RC1 is more preferably 0.2% or less. Thus, for example, the thermal paste remaining area RA becomes 60% or more. the

When the relative degree of curvature RC1 is less than 0.03%, the weight of the metal plate 51 may increase and the cost may increase. When the relative degree of warping RC1 is less than 0.03%, the metal plate 51 may bend in the opposite direction to that of the case where the relative degree of warping RC1 is high, which may impose a burden on screws and the like, and fixation may become unstable. the

In embodiment, for example, relative curvature RC1 is made into 0.28 % or less. Thereby, high reliability can be obtained. the

Fig. 5 is a graph illustrating characteristics of a light emitting device and a lighting device. the

Fig. 5 illustrates the results of the reliability test. The horizontal axis in FIG. 5 is the relative thickness RT1. The relative thickness RT1 is t51/Lmax. The relative thickness RT1 is the ratio of the thickness t51 of the metal plate 51 to the maximum length (maximum length Lmax) of the inner portion 51i. the

As can be seen from FIG. 5 , when the relative thickness RT1 is 0.042 or more, a tendency to improve the thermal paste residual area ratio RA is observed. Preferably, RT1 is 0.050 or more. Accordingly, for example, the thermal paste residual area ratio RA becomes 50% or more. More preferably, RT1 is 0.056 or more. Thereby, for example, the thermal paste residual area RA becomes 60% or more. the

The relative thickness RT1 is preferably 0.13 or less. When the relative thickness RT1 is greater than 0.13, the weight of the metal plate 51 may increase and the cost may increase. When the relative thickness RT1 is larger than 0.13, the metal plate 51 may be bent in the opposite direction when the relative thickness RT1 is small, which may impose a burden on the screws or the like, and fixation may become unstable. the

In embodiment, relative thickness RT1 is made into 0.055 or more. Thereby, high reliability can be obtained. the

In the experiments described above, the metal plate 51 was a copper plate, and the ceramic substrate 10 was an alumina substrate. The embodiment is not limited thereto, and the same result can be obtained even if an aluminum plate is used as the metal plate 51 . That is, as described above, the thermal paste remaining area ratio RA, which is an index of reliability, depends on the degree of warpage C51 (that is, the relative degree of warpage RC1 ). The degree of warpage C51 occurs due to the difference in thermal expansion between the metal plate 51 and the ceramic substrate 10 . The degree of warpage C51 also depends on the size in addition to the thermal expansion coefficient of the material. The thermal expansion coefficient of the ceramic substrate 10 is smaller than that of the metal plate 51 . This difference is larger than the difference between materials (copper or aluminum, etc.) used as the metal plate 51 . Therefore, even when a material other than copper is used as the material of the metal plate 51, the same result as above can be obtained. the

In the embodiment, the distance between the inner portion 51i and the base member 71 varies with temperature. This change leads to the occurrence of a draw-out phenomenon, which lowers (degrades or worsens) heat dissipation and shortens the life of the product. That is, the outer edge portion 51o is fixed to the base member 71 by the fixing portion 75, but the relative position of the inner portion 51i in the Z-axis direction changes with temperature changes. For example, the temperature change in the distance between the inner portion 51 i and the base member 71 is greater than the temperature change in the distance between the outer edge portion 51 o and the base member 71 . the

At this time, by keeping the relative curvature RC1 small, the thermal paste remaining area ratio RA can be kept large. When the relative thickness RT1 is 0.055 or more, high reliability can be maintained. the

FIG. 6 is a schematic cross-sectional view illustrating the light emitting device in the first embodiment. the

FIG. 6 illustrates a part of the light emitting unit 40 as an example. the

As shown in FIG. 6, the first metal layer 11 includes a copper layer 13a (Cu layer). The first metal layer 11 may further include a gold layer 13d (Au layer). The copper layer 13 a is provided between the gold layer 13 d and the ceramic substrate 10 . In this example, the first metal layer 11 also includes: a nickel layer 13b (Ni layer) disposed between the copper layer 13a and the gold layer 13d, and a palladium layer 13c (Ni layer) disposed between the nickel layer 13b and the gold layer 13d. Pd layer). Thus, in this example, the first metal layer 11 has a stacked structure of Cu/Ni/Pd/Au. the

On the other hand, the second metal layer 12 includes a copper layer 14a. The second metal layer 12 may further include a gold layer 14d. The copper layer 14 a is disposed between the gold layer 14 d and the ceramic substrate 10 . In this example, the second metal layer 12 further includes: a nickel layer 14b disposed between the copper layer 14a and the gold layer 14d, and a palladium layer 14c disposed between the nickel layer 14b and the gold layer 14d. Thus, in this example, the second metal layer 12 has a stacked structure of Cu/Ni/Pd/Au. the

In the above description, the boundaries among the copper layer, the nickel layer, the palladium layer, and the gold layer are sometimes unclear. Some of these layers may have mixed states (eg alloy states). the

For the second metal layer 12 , for example, the same material as that of the first metal layer 11 can be used. The same stacked structure as that of the first metal layer 11 can be applied to the second metal layer 12 . This makes it easy to form these metal layers. In the embodiment, the structure of the second metal layer 12 may be different from that of the first metal layer 11 . the

The thickness t11 of the first metal layer 11 is, for example, 30 μm or more and 100 μm or less, for example, 40 μm or more and 60 μm or less. The thickness t12 of the second metal layer 12 is, for example, 30 μm or more and 100 μm or less, for example, 40 μm or more and 60 μm or less. the

The copper layer 13 a of the first metal layer 11 and the copper layer 14 a of the second metal layer 12 can be formed by, for example, electrolytic gold plating. The thickness of the copper layer 13 a and the thickness of the copper layer 14 a are respectively, for example, 30 μm or more and 100 μm or less, for example, about 50 μm. the

The nickel layer 13b, the palladium layer 13c, and the gold layer 13d are formed by, for example, electroless gold plating. The nickel layer 14b, the palladium layer 14c, and the gold layer 14d are formed by, for example, electrolytic gold plating. the

The thickness of the nickel layer 13b and the thickness of the nickel layer 14b are, for example, not less than 2 μm and not more than 8 μm, for example, about 4.5 μm. The thickness of the palladium layer 13 c and the thickness of the palladium layer 14 c are, for example, 0.075 μm or more and 0.2 μm or less, for example, about 0.1 μm, respectively. The thickness of the gold layer 13d and the thickness of the gold layer 14d are, for example, not less than 0.05 μm and not more than 0.2 μm, for example, about 0.1 μm. the

By forming at least a part of the first metal layer 11 and at least a part of the second metal layer 12 by electroless gold plating, the side surfaces of the first metal layer 11 and the side surfaces of the second metal layer 12 can be substantially perpendicular. the

For example, when cutting on a plane (for example, a second plane such as a YZ plane) perpendicular to the first main surface 10a, the side surface 11s of the first metal layer 11 can be substantially parallel to the stacking direction (Z-axis direction). The angle θ between the side surface 11 s of the first metal layer 11 and the first main surface 10 a is, for example, 80 degrees or more and 95 degrees or less. The angle θ is more preferably, for example, 85 degrees or more. the

If the angle θ is small, the area of the lower surface of the mounting pattern 11p becomes too large relative to the area (for example, the area of the upper surface) for mounting the mounting pattern 11p which is a part of the first metal layer 11 . Therefore, in the upper surface (first main surface 10a) of the ceramic substrate 10, the ratio of the portion covered by the mounting pattern 11p becomes high. Therefore, it is difficult to increase the reflectance of the entire mounting region 16 . the

By setting the angle θ between the side surface 11s of the first metal layer 11 and the first main surface 10a to be 80 degrees or more and 95 degrees or less, the upper surface (the first main surface 10a) of the ceramic substrate 10 can be mounted on the upper surface (the first main surface 10a). The ratio of the portion covered by the pattern 11p. Accordingly, the reflectance of the entire mounting region 16 can be sufficiently improved. Thereby, luminosity can be improved. the

The curvature of the corner portion of the cross section of the first metal layer 11 is relatively high. That is, the radius of curvature is small. The cross section of the first metal layer 11 is nearly rectangular, that is, the side 11s is nearly vertical. For example, the first metal layer 11 further has an upper surface 11u parallel to the XY plane (first plane). The radius of curvature of the corner portion 11su connecting the upper surface 11u of the first metal layer 11 and the side surface 11s of the first metal layer 11 is 10 μm or less. Accordingly, the area of the lower surface of the mounting pattern 11p can be made smaller than the area used for mounting the mounting pattern 11p (for example, the area of the upper surface 11u of the mounting pattern 11p). Thereby, the reflectance of the entire mounting region 16 can be improved, and the luminosity can be improved. the

In this example, a part of the wavelength conversion layer 31 is disposed at a position 11 g (space) between any one of the plurality of semiconductor light emitting elements 20 and the ceramic substrate 10 . The position 11g is a position between any one of the mounting patterns 11p (for example, the first mounting pattern 11pa) and the other mounting pattern 11p (for example, the second mounting pattern 11pb). By arranging a part of the wavelength conversion layer 31 also in this position 11g (space), the first light emitted from the semiconductor light emitting element 20 can be efficiently converted into the second light by the wavelength conversion layer 31 . In the position 11g (space), a wavelength conversion member made of transparent resin or other phosphor materials may be separately arranged. the

In order to arrange part of the wavelength conversion layer 31 in the above-mentioned position 11g (space), the space including the position 11g may be enlarged. For example, the gap between the semiconductor light emitting element 20 and the ceramic substrate 10 is increased. For example, the distance tg between any one of the plurality of semiconductor light emitting elements 20 and the ceramic substrate 10 along the Z-axis direction (the stacking direction from the metal plate 51 toward the light emitting portion 40 ) is set to be long. For example, the distance tg is 1/10 or more of the thickness t20 (height) of the plurality of semiconductor light emitting elements 20 along the Z-axis direction. the

For example, the height (thickness t20 along the Z-axis direction) of the semiconductor light emitting element 20 is, for example, 50 μm or more and 500 μm or less, for example, 300 μm. The distance tg is, for example, not less than 40 μm and not more than 110 μm, for example, 60 μm. The distance tg can be increased by increasing the thickness t11 of the first metal layer 11 . the

In an embodiment, the thickness t10 of the ceramic substrate 10 is, for example, not less than 0.3 mm and not more than 2 mm, for example, 0.635 mm. If the thickness t10 of the ceramic substrate 10 is less than 0.3 mm, for example, the mechanical strength of the ceramic substrate 10 will be weakened. If the thickness t10 of the ceramic substrate 10 exceeds 2 mm, for example, heat generated in the semiconductor light emitting element 20 (light emitting element portion 35 ) is conducted to the metal plate 51 with low efficiency. the

As shown in FIG. 6 , the wavelength conversion layer 31 includes a plurality of wavelength conversion particles 31 a such as phosphors, and a translucent resin 31 b in which the plurality of wavelength conversion particles 31 a are dispersed. The wavelength conversion particles 31a absorb at least a part of the first light emitted from the plurality of semiconductor light emitting elements 20, and emit second light having a wavelength different from that of the first light. the

7 is a schematic plan view illustrating a light emitting device and an illuminating device in the first embodiment. the

FIG. 7 illustrates the metal plate 51 . As shown in FIG. 7 , in this example, one hole 58 is provided near each of the four corners of the metal plate 51 . At this time, an outer edge portion 51o and an inner portion 51i as illustrated in FIG. 7 can be defined. the

8a and 8b are schematic diagrams illustrating the light emitting device and the lighting device in the first embodiment. FIG. 8 a is a schematic top view illustrating the metal plate 51 . As shown in FIG. 8a, in this example, the metal plate 51 has no hole 58 on the outer edge portion 51o. In this example, four corners of the metal plate 51 are fixed by the fixing part 75 . By the contact part of the fixing part 75 and the metal plate 51, as shown in FIG. 8a, the outer edge part 51o and the inner part 51i can be defined. the

Fig. 8b is a perspective plan view of the light emitting device and the illuminating device illustrated in Fig. 8a on the YZ plane. the

Fig. 9 is a schematic plan view illustrating the light emitting device and the lighting device in the first embodiment. the

FIG. 9 illustrates the second metal layer 12 . The area of the second metal layer 12 is set larger. The area of the second metal layer 12 is larger than the area of the mounting region 16 . the

The planar pattern of the bonding layer 52 substantially follows the pattern of the second metal layer 12 . By increasing the area of the second metal layer 12, the area of the bonding layer 52 can be enlarged. Thereby, the heat conduction efficiency via the bonding layer 52 can be improved. the

For example, the outer edge 12 r of the second metal layer 12 when projected on the XY plane (first plane) is positioned outside the outer edge 16 r of the mounting region 16 . the

In this example, the corner portion 12c of the outer edge 12r of the second metal layer 12 is curved. The R value in the corner portion 12c is, for example, 1 mm or more. Thereby, the stress generated in the second metal layer 12 and the bonding layer 52 is dispersed, and local deformation is reduced. Distortion of the solder at the corner 12c is reduced. For example, deformation occurring in the ceramic substrate 10 can be reduced, thereby suppressing occurrence of cracks. Thereby, higher reliability can be obtained. the

In the embodiment, when projected on the XY plane, the pattern outer end of the first metal layer 11 is located inside the outer edge 12r of the second metal layer 12 . When projected on the XY plane, the distance between the pattern outer end of the first metal layer 11 and the outer edge 12r of the second metal layer 12 is 2 mm or more. Accordingly, deformation can be further suppressed, and higher reliability can be obtained. the

(second embodiment)

This embodiment relates to a lighting device. The lighting device includes the above-mentioned light emitting device. The lighting device may further include a reflector described below. the

Fig. 10 is a schematic cross-sectional view illustrating a light emitting device and a lighting device in a second embodiment. the

As shown in FIG. 10 , the lighting device 221 in this embodiment includes the light emitting device 121 and the base member 71 . The base member 71 includes, for example, a base 72 and a reflector 73 . In this example, the base 72 has a plate shape. The reflection part 73 is provided along the edge of the base 72 . A light emitting device 121 is provided on the base 72 . The reflector 73 reflects the light LL emitted from the light emitting device 121 . The light LL can be efficiently irradiated in a desired direction by the reflector 73 . The base 72 efficiently releases heat generated by the light emitting device 121 while holding the light emitting device 121 . the

In this example, the light emitting device 121 includes a metal plate 51, a bonding layer 52, and a plurality of light emitting parts 40 (for example, a first light emitting part 40a, a second light emitting part 40b, etc.). the

Also in this example, the ratio of the thickness t51 of the metal plate 51 to the maximum length of the inner portion 51i is set to 0.042 or more. Thereby, high reliability can be obtained. the

In the embodiment, the mounting region 16 is a region where the semiconductor light emitting element 20 is mounted. This area corresponds to the light emitting area. The ratio of the area of the mounting substrate portion 15 to the area of the mounting region 16 is, for example, 2 times or more and 11 or less. The ratio of the area of the metal plate 51 to the area of the mounting region 16 is 6 or more and 33 or less. the

A copper plate can be used for the metal plate 51 . The purity of the copper in the copper plate is, for example, 98% or more. The linear thermal expansion coefficient of the metal plate 51 is, for example, not less than 16 ppm/K and not more than 18 ppm/K. The thermal conductivity of the metal plate 51 is, for example, 300 W/m·K or more. The tensile strength of the metal plate 51 is not less than 250 N/mm ² and not more than 600 N/mm ² . The Vickers hardness of the metal plate 51 is not less than 75 and not more than 160. Thus, high reliability can be easily obtained.

For example, there is a light-emitting device that emits white light by combining a blue LED and a phosphor. As the luminous efficiency (the ratio of the amount of light obtained to the input power) of such light-emitting devices increases, such light-emitting devices are gradually replacing light sources such as light bulbs. Furthermore, for example, a light-emitting device that has a higher light output than a light source for household use and can be mounted on outdoor lighting or high-ceiling lighting is desired. In this light emitting device, for example, the input power is 50 W or more, and the total luminous flux is 5,000 lm or more. In such a high-power light-emitting device, the dielectric breakdown voltage and lightning surge resistance are 5 kV or higher. the

In a high-power light-emitting device, an appropriate heat dissipation structure is required, that is, a low thermal resistance structure is required. According to this embodiment, low thermal resistance can be realized, and high reliability can be obtained. the

According to the embodiment, a highly reliable light emitting device and lighting device are provided. the

In addition, in the present specification, "perpendicular" and "parallel" are not only strictly perpendicular and strictly parallel, but also include, for example, deviations in the manufacturing process, as long as they are substantially perpendicular and substantially parallel. the

As mentioned above, embodiment of this invention was demonstrated with reference to a specific example. However, embodiment of this invention is not limited to these specific examples. For example, regarding a light-emitting unit, a mounted substrate unit, a light-emitting element unit, a substrate, a first metal layer, a second metal layer, a semiconductor light-emitting element, a wavelength conversion layer, a reflective layer, a metal plate, and a bonding layer included in a light-emitting device and a lighting device , the grease layer, the light-reflecting resin layer, the base member, the base, and the reflection part, etc., can be similarly implemented in the present invention as long as those skilled in the art make appropriate selections from the known range. Novel and can obtain same effect, all be included in the scope of the present utility model. the

In addition, a combination of arbitrary two or more elements in each specific example within a technically possible range is included in the scope of the present invention as long as the gist of the present invention is included. the

In addition, all light-emitting devices and lighting devices obtained by those skilled in the art by making appropriate design changes based on the light-emitting devices and lighting devices described above as the embodiments of the present invention, as long as they include the gist of the present invention, All belong to the scope of the present utility model. the

In addition, it can be understood that within the scope of the idea of the present invention, those skilled in the art can conceive of various changes and modifications, and these changes and modifications also belong to the scope of the present invention. the

As mentioned above, although some embodiment of this invention was demonstrated, these embodiment was shown as an example, and it does not mean that the range of the invention is limited. These new embodiments can be implemented in other various forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the scope equivalent thereto. the

Claims (10)

1. A lighting device, comprising: base parts; a plurality of semiconductor light emitting elements separated from the base member; The mounting substrate portion includes a ceramic substrate disposed between the base member and the plurality of semiconductor light emitting elements; a metal plate disposed between the base member and the mounting substrate portion, the metal plate has an outer edge portion and an inner portion inside the outer edge portion, the thickness of the metal plate is equal to a maximum of the inner portion The length ratio is above 0.042; A joining layer is provided between the mounting substrate portion and the metal plate, and joins the mounting substrate portion and the metal plate; a layer of grease disposed between the base member and the metal plate; and The fixing part fixes the outer edge part of the metal plate and the base member. the 2. The lighting device according to claim 1, wherein, The thickness of the metal plate is 4 mm or more. the 3. The lighting device according to claim 1 or 2, wherein, The bonding layer includes solder. the 4. The lighting device according to claim 1 or 2, wherein, The ceramic substrate has: a first main surface and a second main surface on the bonding layer side opposite to the first main surface, The mounting substrate part includes: a first metal layer provided on the first main surface and mounted with the plurality of semiconductor light emitting elements, and a second metal layer provided on the second main surface, The joining layer joins the second metal layer and the metal plate. the 5. The lighting device according to claim 1 or 2, wherein, A distance between the inner portion and the base member varies with temperature, the distance having a greater temperature change than a distance between the outer edge portion and the base member. the 6. The lighting device according to claim 1 or 2, wherein, A circumscribing rectangle of the inner portion is in contact with the fixing portion. the 7. The lighting device according to claim 1 or 2, wherein, The metal plate has a through hole provided on the outer edge, A part of the fixing portion passes through the through hole. the 8. The lighting device according to claim 1 or 2, wherein, A ratio of the degree of warpage of the metal plate to the maximum length of the inner portion is 0.28 or less. the 9. The lighting device according to claim 1 or 2, wherein, The ceramic substrate is an alumina substrate, The metal plate is copper plate. the 10. A light-emitting device, which is fixed to the base member through a fixing part with a grease layer interposed therebetween, the light-emitting device comprising: The mounting substrate part including the ceramic substrate; A plurality of semiconductor light-emitting elements are arranged on one side of the mounting substrate part; a metal plate provided on the other side of the mounting substrate portion and thermally conductively connected to the base member on the other side via the grease layer, the metal plate having an outer portion as a region fixed by the fixing portion. The edge portion and the inner portion inside the outer edge portion, the ratio of the thickness of the metal plate to the maximum length of the inner portion is 0.042 or more; and The bonding layer is provided between the mounting board part and the metal plate, and joins the mounting board part and the metal plate. the