JP7115888B2 - Optical wavelength conversion member and light emitting device - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to light wavelength conversion members and light emitting devices.

In light-emitting devices such as headlamps, various lighting equipment, and laser projectors, the wavelength of light emitted from light-emitting diodes (LEDs, Light Emitting Diodes) and semiconductor lasers (LDs, Laser Diodes) is converted by phosphors, which are light wavelength conversion members. This gives a white color.

Resin-based and glass-based phosphors are known as such phosphors, but ceramic phosphors, which are excellent in durability, are being used in light-emitting devices in order to cope with the increased output of light sources using lasers ( See Patent Document 1).

WO2009/069671

The phosphor generates heat when irradiated with light. When the phosphor heats up to a high temperature, temperature quenching occurs, in which the fluorescence function such as the intensity of light emitted by the phosphor (ie, luminescence intensity or fluorescence intensity) decreases. Therefore, in order for the phosphor to emit light efficiently, it is necessary to exhaust heat from the phosphor to the outside.

However, in conventional light-emitting devices, resin or glass with low thermal conductivity is filled around the ceramic phosphor. As a result, there is a possibility that the fluorescence function may be deteriorated due to insufficient heat exhaustion from the phosphor.

An object of one aspect of the present disclosure is to provide a light wavelength conversion member capable of efficiently exhausting heat from a ceramic phosphor.

One aspect of the present disclosure is a light wavelength conversion member configured to convert the wavelength of incident light. The light wavelength conversion member has a plate-like ceramic phosphor and a metal plate-like frame configured to support the ceramic phosphor. The frame has a first plate portion connected to the side surface of the ceramic phosphor, and a second plate portion arranged so as to overlap the first plate portion in plan view. A gap is formed between the first plate portion and the second plate portion.

According to such a configuration, the heat dissipation property of the ceramic phosphor can be improved by the metal frame having higher thermal conductivity than resin or glass. In addition, since the frame has the first plate portion and the second plate portion, wiring having a relatively high thermal conductivity is secured while securing a space for the light emitting element to be arranged between the ceramic phosphor and the wiring board. A frame can be directly joined to the plate. Furthermore, the formation of the gap between the first plate portion and the second plate portion increases the surface area of the frame, thereby improving heat dissipation. As a result, heat can be efficiently exhausted from the ceramic phosphor.

In one aspect of the present disclosure, the void may constitute a closed space in a cross section parallel to the thickness direction of the ceramic phosphor. According to such a configuration, it is possible to increase the heat exhaust efficiency of the ceramic phosphor while suppressing an increase in the thickness of the frame.

In one aspect of the present disclosure, the first plate portion and the second plate portion may be composed of one continuous plate. With such a configuration, the heat transfer between the first plate portion and the second plate portion is enhanced, so that the heat exhaust efficiency of the ceramic phosphor can be further enhanced.

In one aspect of the present disclosure, the frame may be made of aluminum, copper, nickel, iron, or an alloy combining these. According to such a configuration, it is possible to easily and reliably promote the exhaustion of heat from the ceramic phosphor.

Another aspect of the present disclosure includes the optical wavelength conversion member, a wiring board, and a light emitting element mounted on the wiring board. The frame of the optical wavelength changing member is fixed to the wiring board.
According to such a configuration, it is possible to obtain a light emitting device in which deterioration of the fluorescence function in a high output range is suppressed by efficiently exhausting heat from the ceramic phosphor.

1 is a schematic cross-sectional view of a light emitting device according to an embodiment; FIG. FIG. 2 is a schematic plan view of a light wavelength conversion member in the light emitting device of FIG. 1; 3A is a schematic cross-sectional view of an optical wavelength conversion member in an embodiment different from FIG. 1, and FIG. 3B is a schematic cross-sectional view of an optical wavelength conversion member in an embodiment different from FIGS. 1 and 3A. is. 4A and 4B are schematic cross-sectional views of optical wavelength conversion members of comparative examples, respectively.

Embodiments to which the present disclosure is applied will be described below with reference to the drawings.
[1. First Embodiment]
[1-1. Constitution]
A light emitting device 10 shown in FIG. 1 includes a light wavelength conversion member 1 , a wiring board 11 and a light emitting element 12 .

<Light wavelength conversion member>
The light wavelength conversion member 1 is a member that converts the wavelength of incident light. The light wavelength conversion member 1 has a plate-like ceramic phosphor 2 and a plate-like metal frame 3 .

(Ceramic phosphor)
The ceramic phosphor 2 is a ceramic sintered body having a fluorescent phase mainly composed of crystal grains having fluorescent properties and a translucent phase mainly composed of crystal grains having translucency.

The term "fluorescent phase" refers to a phase mainly composed of crystal grains having fluorescence, and the term "light-transmitting phase" refers to crystal grains having light-transmitting properties, more specifically crystals having a composition different from that of the crystal grains of the fluorescent phase. It is a phase mainly composed of particles.

In addition, "main component" means the component that is present in the largest amount in each phase. For example, the fluorescent phase contains 50% by volume or more, preferably 90% by volume or more of crystal grains having fluorescence. Further, for example, the translucent phase contains 50% by volume or more, preferably 90% by volume or more of crystal grains having translucency.

Each crystal grain and grain boundary of the ceramic sintered body forming the ceramic phosphor 2 may contain inevitable impurities other than the fluorescent phase and the translucent phase. The ceramic sintered body contains the fluorescent phase and the translucent phase in an amount of 50% by volume or more, preferably 90% by volume or more of the ceramic sintered body.

The material of the _{ceramic phosphor 2} is not particularly limited. It preferably has a composition represented by B ₅ O ₁₂ :Ce (that is, a garnet structure).

"A ₃ B ₅ O ₁₂ :Ce" means that Ce is dissolved in A ₃ B ₅ O ₁₂ and part of the element A is substituted with Ce. Crystal grains of the fluorescent phase exhibit fluorescent properties due to solid solution of Ce.

Each of the A element in the chemical formula (1) and the B element in the chemical formula (2) is composed of at least one element selected from the following element group.
A: Sc, Y, lanthanoids (excluding Ce)
(However, A may further contain Gd)
B: Al (however, B may further contain Ga)
By using the ceramic sintered body as the ceramic phosphor 2, light scattering occurs at the interface between the fluorescent phase and the translucent phase, and the angle dependence of the color of light can be reduced. As a result, color uniformity can be improved.

On the other hand, when the ceramic phosphor 2 has a single composition, light scattering does not occur, so the angle dependence of the color of light increases, and there is a risk of unevenness in the color of light. Also, if a resin is used as the phosphor, the thermal conductivity is lowered, and there is a possibility that temperature quenching may occur due to insufficient heat dissipation.

The average thickness (that is, the average distance from the upper surface to the lower surface) of the ceramic phosphor 2 is not particularly limited, but is, for example, 0.1 mm or more and 0.5 mm or less.

(frame body)
The frame 3 is a member that supports the ceramic phosphor 2 . The frame 3 has a first plate portion 3A and a second plate portion 3B.

The material of the frame 3 is not particularly limited as long as it is metal, but from the viewpoint of workability and thermal conductivity, the frame 3 is preferably made of aluminum, copper, nickel, iron, or an alloy combining these. .

The first plate portion 3A is connected to the side surface of the ceramic phosphor 2. As shown in FIG. Specifically, the first plate portion 3A has an opening in the center, and as shown in FIG. 2, the ceramic phosphor 2 is fitted in this opening.

In the present embodiment, the outer shapes of the first plate portion 3A and the ceramic phosphor 2 are rectangular in plan view. Note that the ceramic phosphor 2 may be bonded to the first plate portion 3A with an adhesive or the like.

The second plate portion 3B is arranged so as to overlap with the first plate portion 3A in plan view (that is, when viewed from the thickness direction of the ceramic phosphor 2). In the present embodiment, the second plate portion 3B is superimposed on the wiring board 11 side surface of the first plate portion 3A at two spaced apart locations. The second plate portion 3B is in contact with the first plate portion 3A by folding. The second plate portion 3B may be joined to the first plate portion 3A.

The second plate portion 3B does not overlap the ceramic phosphor 2 in plan view. Further, in the present embodiment, the second plate portion 3B does not have a portion that does not overlap the first plate portion 3A in plan view. That is, the second plate portion 3B exists inside the first plate portion 3A in plan view.

In this embodiment, the first plate portion 3A and the second plate portion 3B are composed of one continuous plate. In other words, the second plate portion 3B is formed by folding inward two opposing ends of a single metal plate.

Specifically, as shown in FIG. 2, two ends of the first plate portion 3A facing in the horizontal direction (X direction) of FIG. is formed. On the other hand, the two ends facing each other in the vertical direction (Y direction) in FIG. 2 are not folded back. Therefore, the second plate portion 3B is not arranged in the central portion (that is, the upper side and the lower side of the ceramic phosphor 2 in FIG. 2) at the end in the Y direction in FIG.

As shown in FIG. 1, the second plate portion 3B is fixed to the surface of the wiring board 11 on which the light emitting element 12 is mounted on the surface opposite to the surface on the first plate portion 3A side. As a method for fixing the second plate portion 3B to the wiring board 11, for example, bonding with an adhesive can be used. This adhesive preferably has a thermal conductivity equal to or higher than that of the frame 3, and is preferably a metal adhesive (brazing material or the like), for example.

The average thickness of the first plate portion 3A and the second plate portion 3B is designed according to the average thickness of the ceramic phosphor 2 . Therefore, the average thickness of each of the first plate portion 3A and the second plate portion 3B is not particularly limited, but is, for example, 0.1 mm or more and 0.5 mm or less.

Furthermore, two gaps 4 are formed between the first plate portion 3A and the second plate portion 3B. In this embodiment, one gap 4 is formed in each of the folded portions of the first plate portion 3A on both the left and right sides in FIG.

Further, in the present embodiment, each void 4 constitutes a closed space in a cross section parallel to the thickness direction of the ceramic phosphor 2 and crossing the end face 3C of the second plate portion 3B (that is, the cross section shown in FIG. 1). It is surrounded by the first plate portion 3A and the second plate portion 3B.

In other words, in the above cross section, the second plate portion 3B has a folded front end portion of the surface facing the first plate portion 3A that abuts the first plate portion 3A, and the surface that faces the first plate portion 3A. The root portion of the folded portion is separated from the first plate portion 3A.

Therefore, each gap 4 is defined by the inner surface of the folded second plate portion 3B (that is, the surface facing the first plate portion 3A) and the inner surface of the folded first plate portion 3A (that is, the second plate The surface facing the portion 3B).

Each gap 4 is cylindrical and communicates with the outside of the frame 3 at both ends thereof. Each gap 4 can be formed, for example, by folding back the end of the metal plate while rolling a pin, and then removing the pin.

<Wiring board>
Wiring board 11 has an insulating layer and wiring provided on this insulating layer. As the insulating layer, for example, a ceramic substrate, a metal substrate coated with an insulating layer, a glass substrate, a resin substrate, a composite substrate, or the like is used. The wiring is composed of a metal thin film or the like.

<Light emitting element>
The light emitting element 12 is, for example, a semiconductor light emitting element such as an LED element. As the light emitting element 12, a nitride semiconductor capable of efficiently exciting the ceramic phosphor 2 is preferable. Note that the light-emitting device 10 may include a plurality of light-emitting elements 12 .

The light emitting element 12 is mounted on the wiring board 11 by flip-chip (that is, facedown). Electrodes of the light emitting element 12 are electrically connected to wiring of the wiring board 11 . Light emitting element 12 may be mounted on wiring board 11 by wire bonding.

The lower surface of the ceramic phosphor 2 is in contact with the light emitting surface of the light emitting element 12 . In other words, the light emitting element 12 is arranged so as to be sandwiched between the ceramic phosphor 2 and the wiring board 11 .

Moreover, as shown in FIG. 1, the light emitting element 12 faces the two end surfaces 3C of the second plate portion 3B. That is, the light emitting element 12 is arranged between the two end surfaces 3C of the second plate portion 3B. The gap between the light emitting element 12 and the light wavelength conversion member 1 may be filled with resin for fixing and protecting the light emitting element 12 .

[1-2. effect]
According to the embodiment detailed above, the following effects are obtained.
(1a) The heat dissipation of the ceramic phosphor 2 can be improved by the metal frame 3 having higher thermal conductivity than resin or glass. In addition, since the frame 3 has the first plate portion 3A and the second plate portion 3B, heat conduction is achieved while securing a space for the light emitting element 12 to be arranged between the ceramic phosphor 2 and the wiring board 11. The frame 3 can be directly joined to the wiring board 11 with a relatively high rate. Furthermore, by forming the gap 4 between the first plate portion 3A and the second plate portion 3B, the surface area of the frame 3 is increased and the heat dissipation is improved. As a result, the heat of the ceramic phosphor 2 can be efficiently exhausted.

(1b) The gap 4 forms a closed space in a cross section parallel to the thickness direction of the ceramic phosphor 2, thereby suppressing an increase in the thickness of the frame 3 and increasing the heat exhaust efficiency of the ceramic phosphor 2. .

(1c) The heat transfer between the first plate portion 3A and the second plate portion 3B is enhanced by forming the first plate portion 3A and the second plate portion 3B from one continuous plate. As a result, the heat exhaust efficiency of the ceramic phosphor 2 can be improved.

[2. Other embodiments]
Although the embodiments of the present disclosure have been described above, it is needless to say that the present disclosure is not limited to the above embodiments and can take various forms.

(2a) In the light wavelength conversion member 1 of the above-described embodiment, the first plate portion 3A and the second plate portion 3B of the frame 3 do not necessarily have to be composed of one continuous plate. That is, as shown in FIG. 3A, each of the first plate portion 3A and the second plate portion 3B may be composed of one plate. In this case, the second plate portion 3B is joined to the first plate portion 3A by adhesion using paste, brazing material, or the like, or by thermocompression.

(2b) In the light wavelength conversion member 1 of the above embodiment, the voids 4 do not necessarily have to form closed spaces in the cross section parallel to the thickness direction of the ceramic phosphor 2 . That is, as shown in FIG. 3B, the entire inner surface of the second plate portion 3B facing the first plate portion 3A may be separated from the first plate portion 3A.

(2c) The function of one component in the above embodiment may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Also, part of the configuration of the above embodiment may be omitted. Also, at least a part of the configuration of the above embodiment may be added, replaced, etc. with respect to the configuration of the other above embodiment. It should be noted that all aspects included in the technical idea specified by the wording in the claims are embodiments of the present disclosure.

[3. Example]
The following describes the contents of the test conducted to confirm the effects of the present disclosure and the evaluation thereof.

<Reference example 1>
A 1 mm square ceramic phosphor having an average thickness of 0.2 mm was irradiated with a laser beam, and the laser output was gradually increased. The laser output was 1 W when temperature quenching occurred.

<Reference example 2>
A light wavelength conversion member was prepared by fitting the ceramic phosphor of Reference Example 1 in the center of a 10 mm square metal frame made of aluminum and having an average thickness of 0.2 mm. When the same test as in Reference Example 1 was performed on this optical wavelength conversion member, the laser output when temperature quenching occurred was 6W.

<Comparative Example 1>
As shown in FIG. 4A, a light wavelength conversion member 101 was produced by bonding a second plate portion 103B to the metal frame (first plate portion 103A) of Reference Example 2 in which the ceramic phosphor 2 was fitted. No gap is formed between the first plate portion 103A and the second plate portion 103B. This optical wavelength conversion member was irradiated with a laser beam while blowing a wind of 1 m/sec, and the laser output was gradually increased. The laser output was 7W when temperature quenching occurred.

<Comparative Example 2>
As shown in FIG. 4B, the end portion of the metal frame of Reference Example 2 in which the ceramic phosphor 2 is fitted is folded back to form a first plate portion 203A and a second plate portion 203B to produce a light wavelength conversion member 201. did. No gap is formed between the first plate portion 203A and the second plate portion 203B. When this optical wavelength conversion member was subjected to the same test as in Comparative Example 1, the laser output was 10 W when temperature quenching occurred.

<Example 1>
When the same test as in Comparative Example 1 was performed on the optical wavelength conversion member 1 of FIG. 1, the laser output was 11 W when temperature quenching occurred.

<Example 2>
When the same test as in Comparative Example 1 was performed on the optical wavelength conversion member 1 of FIG. 3B, the laser output was 13 W when temperature quenching occurred.

<Discussion>
From the above results, it can be seen that heat dissipation is improved by providing a gap between the first plate portion 3A and the second plate portion 3B.

DESCRIPTION OF SYMBOLS 1... Optical wavelength conversion member, 2... Ceramic fluorescent substance, 3... Frame, 3A... First plate part,
3B... second plate portion, 3C... end surface, 4... void, 10... light emitting device, 11... wiring board,
12... A light-emitting element.

Claims (4)

A light wavelength conversion member configured to convert the wavelength of incident light,
a plate-like ceramic phosphor;
a metal plate-shaped frame configured to support the ceramic phosphor;
has
The frame is
a first plate portion connected to the side surface of the ceramic phosphor;
a second plate portion arranged to overlap the first plate portion in a plan view;
has
A gap is formed between the first plate portion and the second plate portion ,
The light wavelength conversion member , wherein the void constitutes a closed space in a cross section parallel to the thickness direction of the ceramic phosphor . A light wavelength conversion member configured to convert the wavelength of incident light,
a plate-like ceramic phosphor;
a metal plate-shaped frame configured to support the ceramic phosphor;
has
The frame is
a first plate portion connected to the side surface of the ceramic phosphor;
a second plate portion arranged to overlap the first plate portion in a plan view;
has
A gap is formed between the first plate portion and the second plate portion,
The optical wavelength conversion member, wherein the first plate portion and the second plate portion are composed of one continuous plate. A light wavelength conversion member configured to convert the wavelength of incident light,
a plate-like ceramic phosphor;
a metal plate-shaped frame configured to support the ceramic phosphor;
has
The frame is
a first plate portion connected to the side surface of the ceramic phosphor;
a second plate portion arranged to overlap the first plate portion in a plan view;
has
A gap is formed between the first plate portion and the second plate portion,
The light wavelength conversion member, wherein the frame is made of aluminum, copper, nickel, iron, or an alloy combining these. the optical wavelength conversion member according to any one of claims 1 to 3 ;
a wiring board;
a light emitting element mounted on the wiring board;
with
The light-emitting device, wherein the frame of the light wavelength conversion member is fixed to the wiring board.

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