JP7594205B2 - Light-emitting device - Google Patents

Description

The present invention relates to a light-emitting device.

Patent Document 1 describes a semiconductor laser device that includes a stem including a block portion and an eyelet portion on the upper surface of which the block portion is provided, a semiconductor laser element mounted on the block portion, a cap fixed on the upper surface of the eyelet portion so as to cover the semiconductor laser element, and a lead held in the eyelet portion. The lower surface of the eyelet portion is in thermal contact with a heat sink for dissipating heat from the semiconductor laser element. It also describes that the lead may be fixed to the lower surface of the eyelet portion or to the side surface.

JP 2011-18800 A

In Patent Document 1, because the leads are fixed to the stem, the through-hole that is the lead fixing portion limits the path for transporting heat generated by the semiconductor laser element to the heat sink. Furthermore, in order to improve airtightness, it is necessary to select a stem material with a thermal expansion coefficient close to that of the leads and the sealing material used to fix the leads. If a stem material has a thermal expansion coefficient significantly different from that of the leads, etc., gaps will occur at the interface between the stem and the leads, etc., due to temperature changes when the semiconductor laser device is operated, which will likely reduce the airtightness of the semiconductor laser device.

This application includes the following inventions.
a base having a mounting portion protruding upward from a main surface;
a terminal holding member having an annular shape and joined to the main surface of the base so as to surround the mounting portion;
a cap joined to an upper surface of the terminal holding member and constituting a sealed space together with the base and the terminal holding member;
a semiconductor laser element provided on a side surface of the mounting portion;
a lead terminal passing through the terminal holding member;
A light emitting device comprising:

It is possible to provide a highly reliable light-emitting device with excellent heat dissipation characteristics and airtight performance.

1 is a schematic perspective view of a light emitting device according to a first embodiment. 1 is a schematic top view of a light emitting device according to a first embodiment. 1 is a schematic side view of a light emitting device according to a first embodiment. 3 is a schematic cross-sectional view taken along line AA in FIG. 2. 2 is a schematic perspective view showing a state before a cap is bonded to the light emitting device according to the first embodiment. FIG. 3 is a schematic side view showing a state before a cap is bonded to the light emitting device according to the first embodiment. FIG. FIG. 2 is a schematic perspective view of a heat dissipation plate and a current-carrying member. FIG. 11 is a schematic perspective view showing an example in which a plurality of light emitting devices are mounted. FIG. 11 is a schematic top view of a light emitting device according to a second embodiment. FIG. 11 is a schematic side view of a light emitting device according to a second embodiment. FIG. 11 is a schematic perspective view of a light emitting device according to another embodiment. FIG. 13 is a schematic top view of a light emitting device according to another embodiment. FIG. 11 is a schematic perspective view showing a state before a cap is bonded to a light emitting device according to another embodiment. FIG. 13 is a schematic top view showing a state before the cap is bonded to a light emitting device according to another embodiment.

The following describes an embodiment of the present invention with reference to the drawings. However, the embodiment described below is merely an example of a method for realizing the technical concept of the present invention, and does not limit the present invention to the following embodiment. Furthermore, in the following description, the same names and symbols indicate the same or similar components, and detailed descriptions will be omitted as appropriate.

<Embodiment 1>
Fig. 1 is a schematic perspective view of a light emitting device 100 according to the first embodiment. Fig. 2 is a schematic top view of the light emitting device 100, and Fig. 3 is a schematic side view of the light emitting device 100 as viewed from the side from which the lead terminals 13A and 13B of the light emitting device 100 protrude. Fig. 4 is a schematic cross-sectional view taken along line A-A in Fig. 2. Fig. 5 is a schematic perspective view showing the state of the light emitting device 100 before the cap 12 is bonded, and Fig. 6 is a schematic side view showing the same state.

1 to 6, the light emitting device 100 has a base 10, a terminal holding member 11, a cap 12, lead terminals 13A and 13B, and a semiconductor laser element 14. The base 10 has a mounting portion 10a that protrudes upward from its main surface. The annular terminal holding member 11 is bonded to the main surface of the base 10 so as to surround the mounting portion 10a. The cap 12 is bonded to the upper surface of the terminal holding member 11, and forms a sealed space 17 together with the base 10 and the terminal holding member 11.
The semiconductor laser element 14 is provided on a side surface of the mounting portion 10a. The lead terminals 13A and 13B pass through the terminal holding member 11.

In the light emitting device 100, the lead terminals 13A and 13B are held by a terminal holding member 11 joined to the base 10. In detail, through holes larger than the outer diameter of the lead terminals 13A and 13B are provided on the side of the terminal holding member 11, the lead terminals 13A and 13B are arranged so as to pass through the through holes, and an insulating material 15 is provided between the through holes and the lead terminals. Since the terminal holding member 11 is typically made of a metal, which is a conductive material, filling the gap between the terminal holding member 11 and the lead terminals 13A and 13B with the insulating material 15 prevents short circuits of the lead terminals 13A and 13B and ensures sufficient airtightness.

In this way, in the light emitting device 100, a terminal holding member 11 is provided in addition to the base 10 to allow the lead terminals 13A and 13B to protrude from the sides. This allows the entire bottom surface of the base 10 to be connected to a heat sink or the like, allowing heat to be dissipated more efficiently from the bottom surface of the base 10. Furthermore, if a through hole is provided in the base 10, the heat from the semiconductor laser element 14 needs to bypass the through hole to reach the heat sink or the like, but since the base 10 does not have such a through hole, it is possible to dissipate heat efficiently. Furthermore, since the cap 12 is bonded to the terminal holding member 11 instead of the base 10, a material with high thermal conductivity can be used as the material for the base 10, improving heat dissipation. This is for the following reasons.

First, the cap 12 is joined after the semiconductor laser element 14 is mounted, so resistance welding is typically used as a joining method that can be performed at low temperatures. For this reason, a material suitable for resistance welding is selected for the cap 12. In addition, since the joining area is small in resistance welding and there is a risk of delamination resulting in a decrease in airtightness when joining members with different linear expansion coefficients, it is suitable for the member to be joined to the cap 12 to have a linear expansion coefficient close to that of the cap 12. If the cap 12 is joined to the base 10, the material of the base 10 must be selected from those with a linear expansion coefficient close to that of the cap 12, but this makes it difficult to use a material with good heat dissipation. Therefore, in the light-emitting device 100, the cap 12 is joined to the terminal holding member 11. As a result, it is sufficient for the terminal holding member 11 to use a material with a linear expansion coefficient close to that of the cap 12, and a material with high thermal conductivity can be used for the base 10 regardless of the linear expansion coefficient. In addition, since the base 10 and the terminal holding member 11 can be bonded before mounting the semiconductor laser element 14, a bonding method with a large bonding area, such as bonding with a metal adhesive, can be used. Therefore, even if the difference in linear expansion coefficient between the terminal holding member 11 and the base 10 is relatively large, they are unlikely to peel off to the extent that their airtightness is reduced. Therefore, a material with high thermal conductivity can be selected for the base 10 regardless of the linear expansion coefficient. In addition, the material that holds the lead terminals 13A and 13B needs to have a linear expansion coefficient close to that of the lead terminals 13A and 13B and the insulating material 15, but in the light emitting device 100, this material is also the terminal holding member 11. Therefore, from this point of view, a material with high thermal conductivity can be selected for the base 10 regardless of the linear expansion coefficient.

The base 10 is preferably made of a material with high thermal conductivity. This allows the heat generated by the semiconductor laser element to be efficiently removed. Specifically, the preferred material for the base 10 is copper or a copper alloy. The surface may be gold plated. The heat generated by the semiconductor laser element 14 is dissipated to the outside from the main surface (lower surface) of the base 10 opposite the mounting portion 10a via the mounting portion 10a. For heat dissipation, the lower surface of the base 10 is preferably attached to a heat sink such as a heat sink plate. The heat sink and the lower surface of the base 10 can be connected by grease or the like. As shown in FIG. 2, the outer edge of the base 10 in the top view can be made substantially circular. The outer edge of the base 10 may be provided with a recess.
The depression has a shape of, for example, a substantially triangular shape or a substantially rectangular shape in top view. Such a depression is used as a guide for aligning the orientation of the base body 10, for example.

In addition, it is preferable that the side surface of the mounting portion 10a on which the semiconductor laser element 14 is provided is approximately perpendicular to the lower surface of the base 10. This allows the optical axis of the laser light emitted by the semiconductor laser element 14 to be approximately perpendicular to the lower surface of the base 10. In addition, the mounting portion 10a may be separate from the base portion of the base 10, but it is preferable that they are integrated. If there is a gap between the mounting portion 10a and the base portion, the heat transport efficiency will decrease, but if they are integrated, this can be avoided. For example, the base 10 including the mounting portion 10a is formed by press-molding a copper alloy plate. It is preferable that the side surface on which the semiconductor laser element 14 is provided is a flat surface. Note that, when the mounting portion and the base portion are made of different materials, it is preferable that the mounting portion 10a is made of a material with high thermal conductivity. Specifically, a preferable material for the mounting portion 10a is copper or a copper alloy. The surface may be gold-plated.

It is preferable that the difference in thermal expansion coefficient between the terminal holding member 11 and the lead terminals 13A and 13B is smaller than the difference in thermal expansion coefficient between the base 10 and the lead terminals 13A and 13B. Specific examples of the material of the terminal holding member 11 include an alloy containing iron. The surface may be gold plated. In addition, if the base 10 is made of a material with good thermal conductivity, it is considered that the linear expansion coefficient of the cap 12 will be different. For this reason, it is preferable that the terminal holding member has a linear expansion coefficient intermediate between the cap 12 (holding portion 12b) and the base 10. The terminal holding member 11 is joined to the base 10 by a metal adhesive such as silver solder. Typically, the width of the joint between the base 10 and the terminal holding member 11 is larger than the width of the joint between the terminal holding member 11 and the cap 12. In order to ensure airtightness by sufficiently joining the terminal holding member 11 to the base 10, it is preferable that the outer edge of the terminal holding member 11 is located inside the outer edge of the base 10 when viewed from above. In addition, since the cap 12 is bonded to the upper surface of the terminal holding member 11, it is preferable that the thickness of the terminal holding member 11 is greater than the thickness of the cap 12. For example, the thickness is 0.25 mm.

As shown in FIG. 2, in a top view, the outer edge of the terminal holding member 11 preferably includes a close portion 11a close to the outer edge of the base 10 and a separated portion 11b that is farther from the outer edge of the base 10 than the close portion 11a. The lead terminals 13A and 13B protrude from the separated portion 11b. By arranging them in this manner, the lead terminals 13A and 13B can be stored above the base 10, making it easy to arrange multiple light emitting devices 100 in close proximity. In a top view, the separated portion 11b is preferably linear. By providing a through hole that penetrates almost perpendicularly to a nearly flat surface in this manner, a cylindrical through hole is formed. Then, the lead terminals 13A and 13B can be firmly fixed by assembling them using a cylindrical insulating material 15. The size of the through hole through which the lead terminals 13A and 13B pass is, for example, φ1.2 mm.

The shape of the adjacent portion 11a in top view is preferably approximately the same as a part of the shape of the base 10 in top view. For example, as shown in FIG. 2, if the outer edge of the base 10 is approximately circular, the adjacent portion 11a is composed of a concentric arc with a smaller radius than the outer edge of the base 10. If a depression is provided on the outer edge of the base 10, the shape of the outer edge of the base 10 ignoring the depression may be considered as the shape of the outer edge of the base 10. In addition, the length of the separated portion 11b in top view can be approximately longer than the radius of the arc of the adjacent portion 11a.

The terminal holding member 11 is bonded by, for example, placing it on the base 10 coated with silver solder, with the lead terminals 13A and 13B fixed in place with the insulating material 15, and heating it. Usually, the semiconductor laser element 14 and other components are mounted after this. For this reason, it is preferable that the upper end of the terminal holding member 11 is located lower than the semiconductor laser element 14 and other components mounted on the side of the mounting portion 10a.

The light emitting device 100 has at least two lead terminals 13A and 13B. For example, the lead terminal 13A is an anode side terminal, and the lead terminal 13B is a cathode side terminal. The lead terminals 13A and 13B are made of a material with good electrical conductivity. Specific examples include an alloy of iron, nickel, and kovar, and an alloy of iron and nickel. The surface may be gold plated. The shape of the lead terminals 13A and 13B is, for example, cylindrical or bent cylindrical. The diameter of the cross section perpendicular to the extension direction of the lead terminals 13A and 13B is, for example, 0.6 mm.

As shown in FIG. 4, the lead terminals 13A and 13B are preferably bent to include the first portion 13Ba and the second portion 13Bb. The first portion 13Ba is a portion that extends in a direction along the side surface of the mounting portion 10a inside the sealed space 17 formed by the base 10, the terminal holding member 11, and the cap 12, and is a portion to which the wire 16 for electrically connecting to the semiconductor laser element 14 is joined. The second portion 13Bb is a portion that extends in a direction along the main surface of the base 10, penetrates the terminal holding member 11, and is disposed outside the sealed space 17. By having such a first portion 13Ba, the wire bonding surface of the semiconductor laser element 14, etc. and the wire bonding surfaces of the lead terminals 13A and 13B can be oriented in the same direction. Therefore, a light emitting device 100 with excellent mass productivity can be obtained.

The first portion 13Ba extending in a direction along the side surface of the mounting portion 10a is typically arranged so as to be approximately parallel to the side surface of the mounting portion 10a. The second portion 13Bb extending in a direction along the main surface of the base 10 is typically arranged so as to be approximately parallel to the main surface of the base 10. In other words, the lead terminals 13A and 13B are typically L-shaped.

In addition, when viewed from above, it is preferable that one end of the lead terminals 13A and 13B that is located outside the sealed space 17 is located inside the outer edge of the base 10. In other words, it is preferable that the lead terminals 13A and 13B are completely contained above the base 10. This allows the outer edge of the light emitting device 100 to be aligned with the outer edge of the base 10, so that multiple light emitting devices 100 can be arranged in close proximity. If the base 10 is not electrically connected to the semiconductor laser element 14, multiple light emitting devices 100 may be arranged close enough that the bases 10 are in contact.

The through holes of the terminal holding member 11 are filled with insulating material 15, which fixes the lead terminals 13A and 13B. The insulating material 15 is made of, for example, a glass material. To achieve airtight sealing, the insulating material 15 is preferably made of a material with a thermal expansion coefficient close to that of the terminal holding member 11 and the lead terminals 13A and 13B, such as borosilicate glass. Airtightness can be ensured by pressing the insulating material 15 against the terminal holding member 11.

Because the cap 12 is bonded to the upper surface of the terminal holding member 11, it is preferable that the outer edge of the cap 12 is substantially the same as the outer edge of the terminal holding member 11, but is disposed inside it, in a top view. The cap 12 has a window portion 12a and a holding portion 12b. The window portion 12a is a light-transmitting member disposed in a through hole of the holding portion 12b. Light from the semiconductor laser element 14 is extracted from the window portion 12a. For example, the window portion 12a is a glass part having a diameter of φ2.3 mm and a thickness of 0.3 mm, and is bonded to the holding portion 12b by low-melting point glass. The shape of the window portion 12a in a top view is, for example, a circular shape. In a top view, the window portion 12a is typically disposed in the center of the base 10. The holding portion 12b and the terminal holding member 11 are bonded, for example, by welding. The holding portion 12b is made of, for example, stainless steel (SUS).

The semiconductor laser element 14 is, for example, a nitride semiconductor laser element. The oscillation wavelength can be in the ultraviolet to green range. The semiconductor laser element 14 may be attached to the mounting portion 10a via a submount 18. The submount 18 is typically a component with high electrical insulation and high thermal conductivity. Examples include aluminum nitride and silicon carbide. For example, metal layers are provided on both the front and back surfaces of an insulating silicon carbide substrate, the semiconductor laser element 14 is fixed to the metal layer on the front surface, and is fixed to the mounting portion 10a by the metal layer on the back surface.

An example of mounting multiple light emitting devices 100 is shown in Figures 7 and 8. As shown in Figures 7 and 8, the base 10 of the light emitting device 100 is fixed directly or via grease, solder, etc. to each of the multiple recesses 20a of the heat dissipation plate 20. The shape and size of the recesses 20a are approximately the same as those of the base 10. The through holes 20b are for fixing, and for example, screws are inserted to fix the heat dissipation plate 20 to a heat sink or the like. Note that through holes may be used instead of the recesses 20a. In this case, the base 10 of the light emitting device 100 may be thermally connected to the heat sink or the like directly or via grease, etc.

By disposing the current-carrying member 30 between the base 10 and the lead terminals 13A and 13B, it is possible to supply power to the multiple light-emitting devices 100. Wires 31a to 31j are provided on the surface of the current-carrying member 30, and are electrically connected to the lead terminals 13A and 13B by solder or the like. The wires 31a to 31j are connected by internal wiring provided inside the current-carrying member 30 so that the multiple light-emitting devices 100 are connected in series. That is, wires 31b and 31c are connected, wires 31d and 31e are connected, wires 31f and 31g are connected, and wires 31h and 31i are connected. The current-carrying member 30 may be further connected to external wiring, with wire 31a serving as the anode side and wire 31j serving as the cathode side, for example.

A number of light emitting devices 100 connected in series in this way may be arranged in several rows, and the light emitting portions (window portions 12a) of the light emitting devices 100 may be arranged in a matrix. Since the lead terminals 13A and 13B of the light emitting device 100 are located above the base 10, another light emitting device 100 may be arranged adjacent to the protruding side of the lead terminals 13A and 13B.

<Embodiment 2>
Fig. 9 is a schematic top view of the light emitting device 200 according to the second embodiment, and Fig. 10 is a schematic side view of the light emitting device 200. As shown in Figs. 9 and 10, the light emitting device 200 according to the second embodiment differs from the light emitting device 100 according to the first embodiment in that the terminal holding member 211 is annular in top view. In this case, a cylindrical cap 212 can be used. The cylindrical cap 212 may be the same as that of a conventional light emitting device in which a lead terminal is provided by penetrating a base.

As shown in FIG. 9, the direction in which the lead terminals 213A and 213B penetrate the terminal holding member 211 in a top view is preferably a direction extending radially from the center of the light emitting device 200. This makes it possible to suppress the amount of protrusion of the lead terminals 213A and 213B from the base 210 in a top view, so that multiple light emitting devices 200 can be arranged in close proximity. This is particularly preferable when multiple light emitting devices 200 are arranged vertically and horizontally in a matrix shape. In addition, since the through holes provided in the terminal holding member 211 can be made to have a shape close to a cylinder, the lead terminals 213A and 213B can be fixed using a cylindrical insulating material 215. The cylindrical insulating material 215 can be produced by cutting out a wire material, so that it can be produced inexpensively. The insulating material 215 may protrude from the terminal holding member 211 in a top view.

<Other embodiments>
Other embodiments will be described with reference to Figures 11 to 14. This embodiment differs from the light emitting device of the first embodiment in that the semiconductor laser element is provided on the upper surface of the mounting portion, and that the upper surface of the mounting portion is further provided with a light reflecting member (light reflecting mirror) that changes the direction of the light emitted from the semiconductor laser element from a direction parallel to the upper surface of the mounting portion to a direction perpendicular thereto, but is otherwise the same as the first embodiment.

The light emitting device 300 of another embodiment includes a base 310 having a mounting portion 310a protruding upward from its main surface, a ring-shaped terminal holding member 311 bonded to the main surface of the base 310 so as to surround the mounting portion 310a, a cap 312 bonded to the upper surface of the terminal holding member 311 and constituting a sealed space together with the base 310 and the terminal holding member 311, a semiconductor laser element 314 and a light reflecting member 319 provided on the upper surface of the mounting portion 310a, and lead terminals 313A and 313B passing through the terminal holding member.

Figure 11 is a schematic perspective view of a light emitting device according to another embodiment, Figure 12 is a schematic top view of a light emitting device according to another embodiment, Figure 13 is a schematic perspective view showing the state of a light emitting device according to another embodiment before a cap is bonded, and Figure 14 is a schematic top view showing the state of a light emitting device according to another embodiment before a cap is bonded. Figures 13 and 14 are diagrams for explaining the structure of the sealed space of a light emitting device according to another embodiment.

Here, the cap 312 has a window portion 312a and a holding portion 312b. The window portion 312a is a light-transmitting member disposed in a through hole of the holding portion 312b. Light from the semiconductor laser element 314 travels in a direction parallel to the upper surface of the mounting portion, and is reflected by the light reflecting member 319 in a direction perpendicular to the main surface of the substrate, and is extracted from the window portion 12a. The semiconductor laser element 314 is also electrically connected to the lead terminals 312a and 312b by wires.

The mounting portion 310a protrudes upward from the main surface of the substrate with a size approximately equal to the size of the inside of the annular terminal holding member, but it does not have to protrude. In this case, the mounting portion is a mounting area on the main surface of the substrate, and the mounting area includes the semiconductor laser element 314 and the light reflecting member 319.

100, 200, 300 Light emitting device 10, 210, 310 Base 10a, 310a Mounting portion 11, 211, 311 Terminal holding member 11a Proximal portion, 11b Separated portion 12, 212, 312 Cap 12a, 312a Window portion, 12b, 312b Holding portion 13A, 13B, 213A, 213B, 313A, 313B Lead terminal 13Ba First portion, 13Bb Second portion 14, 314 Semiconductor laser element 15, 215 Insulating material 16 Wire 17 Sealed space 18 Submount 20 Heat dissipation plate 20a Recess, 20b Through hole 30 Current-carrying member 31a to 31j Wiring 319 Light reflecting member

Claims (5)

a base body formed integrally with a base portion having a main surface and a mounting portion protruding upward from the main surface;
a terminal holding member having an annular shape and joined to the main surface of the base so as to surround the mounting portion;
a semiconductor laser element provided on an upper surface of the mounting portion;
a light reflecting member provided on an upper surface of the mounting portion and on which light emitted from the semiconductor laser element is incident;
a first lead terminal passing through the terminal holding member;
a second lead terminal passing through the terminal holding member;
Equipped with
the first lead terminal and the second lead terminal each include a first portion to which a wire for electrical connection to the semiconductor laser element is joined, and a second portion penetrating the terminal holding member;
in a plan view seen from a direction perpendicular to an upper surface of the mounting portion on which the semiconductor laser element is provided, the first portion of the first lead terminal and the first portion of the second lead terminal extend in a direction along an optical axis of laser light emitted by the semiconductor laser element, and the semiconductor laser element is disposed between the first portion of the first lead terminal and the first portion of the second lead terminal,
the light reflecting member is not disposed between the first portion of the first lead terminal and the first portion of the second lead terminal in a plan view seen from a direction perpendicular to an upper surface of the mounting portion on which the semiconductor laser element is provided,
A light emitting device, wherein the first portion and the second portion of the first lead terminal and the second lead terminal extend in the same direction. the first portion of the first lead terminal and the first portion of the second lead terminal extend at equal intervals;
The light emitting device according to claim 1 , wherein the second portion of the first lead terminal and the second portion of the second lead terminal extend with equal intervals between each other. 3. The light emitting device according to claim 1, further comprising a cap joined to an upper surface of said terminal holding member, said cap forming a sealed space together with said base and said terminal holding member. The light emitting device according to any one of claims 1 to 3, wherein a glass material is disposed between the first and second lead terminals and the terminal holding member. The light emitting device according to any one of claims 1 to 4, wherein the outer edge of the terminal holding member is located inside the outer edge of the base in a plan view seen from a direction perpendicular to the upper surface of the mounting portion on which the semiconductor laser element is provided.

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