JP7467877B2 - Semiconductor light emitting device - Google Patents

Description

The present invention relates to a semiconductor light-emitting device.

As semiconductor laser devices become more powerful, efforts have been made to improve the heat dissipation characteristics of the packages.

One example of such technology is a structure in which the heat sink and stem base are made of Cu and are integrally constructed to improve the heat dissipation of the package, and a ring of Fe-based material is brazed to the cap weld for airtight sealing (see, for example, Patent Document 1).
Also, a technique is known in which the heat sink and the base are integrated by pressing (see, for example, Patent Document 2).
Furthermore, there is also a structure in which a heat sink penetrates a base and a heat dissipation portion is provided on the rear surface of the base (see, for example, Patent Document 3).

Patent No. 5866530 Japanese Patent No. 3616698 JP 2004-235212 A

To ensure heat dissipation, a sufficiently large heat dissipation area is required, as well as a structure that prevents heat from returning to the cap.Furthermore, a structure that does not interfere with the hermetic seal achieved by cap welding is also required, but conventional structures cannot satisfy all of these requirements.
SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a semiconductor light emitting device having a structure that satisfies requirements for ensuring heat dissipation and hermetic sealing.

In order to solve the above problem, one aspect of the semiconductor light emitting device according to the present invention includes a base that spreads in a plate shape and has a first through hole that penetrates the front and back surfaces of the base, a cap that covers the first surface side of the front and back surfaces of the base and has a peripheral portion welded to the first surface to form an internal space, a columnar block that has a thermal conductivity higher than that of the base, has a columnar shape, penetrates the first through hole in the extension direction of the columnar shape and protrudes into the internal space, and has a side surface that fits into the first through hole, a heat sink that has a thermal conductivity higher than that of the base, spreads in contact with a second surface behind the first surface, reaches the back side of the location where the peripheral portion is fixed, and is integral with the columnar block or connected to the columnar block, and a light emitting element made of a semiconductor that is directly or indirectly fixed to the side surface of the columnar block.

With this type of semiconductor light-emitting device, the columnar block fitted into the first through hole and the heat sink that contacts the base and reaches the rear side of the peripheral edge of the cap allow for efficient heat dissipation by preventing heat from returning to the internal space. Furthermore, this structure makes it easy to achieve an airtight seal by cap welding.

In the above semiconductor light-emitting device, the light-emitting element is preferably a laser element. Laser elements are required to have particularly high heat dissipation properties in line with the trend toward higher output in recent years.

In the above semiconductor light emitting device, it is preferable that the base has a second through hole separate from the first through hole, and the semiconductor light emitting device further includes a lead pin that passes through the second through hole to supply power to the light emitting element.
By having the columnar block and the lead pin pass through separate through holes, heat return through the base can be more effectively prevented.

In the semiconductor light-emitting device having the above-mentioned lead pin, it is preferable that the lead pin is fixed to the base by melting and bonding an insulating material. This structure achieves both airtight sealing and insulation.

In the semiconductor light emitting device having the lead pins, it is also preferable that the heat sink is not in contact with the lead pins. With this structure, the heat sink and the lead pins are easily insulated from each other.
In the above semiconductor light emitting device, it is preferable that the heat sink is brazed to the base. The heat sink and the base are integrated by brazing, which increases the strength of the device.

In the above semiconductor light emitting device, it is also preferable that the columnar block is brazed to the inner wall of the first through hole. By integrating the columnar block and the base by brazing, movement of the light emitting point due to thermal expansion of the columnar block is suppressed.

The semiconductor light-emitting device of the present invention can ensure heat dissipation and provide airtight sealing.

1 is a diagram showing a semiconductor laser device corresponding to a first embodiment of the present invention; FIG. 13 is a diagram showing heat dissipation by a heat sink. FIG. 1 is a diagram showing the range of expansion of the stem base and the range of expansion of the flange portion. FIG. 13 is a diagram illustrating a semiconductor laser device according to a second embodiment.

The following describes an embodiment of the present invention with reference to the drawings.

Figure 1 shows a semiconductor laser device corresponding to the first embodiment of the present invention, and shows a top view (A), a front view (B), and a cross-sectional view (C). In the front view (B), the inside of the can package is shown as seen through from the outside.

The semiconductor laser device 100 of the first embodiment includes a stem base 101, a heat sink 102, a laser chip 103, a stem cap 104, a power supply lead pin 105, and a wire 106.

The heat sink 102 has a block portion 102a that penetrates the first through-hole 101c from the bottom surface 101b side to the top surface 101a side of the stem base 101 and protrudes into the inside of the can package. The block portion 102a is columnar with a semicircular cross section and fits into the semicircular first through-hole 101c. The flange portion 102b of the heat sink 102 contacts the bottom surface 101b of the stem base 101 and extends along the stem base 101.

The stem cap 104 is fixed to the upper surface 101a of the stem base 101 by welding, and covers the block portion 102a of the heat sink 102 and the upper surface 101a of the stem base 101. The space covered by the stem cap 104 is the internal space of the can package, and this internal space is hermetically sealed.

The stem base 101, heat sink 102, and stem cap 104 are all made of metal, and together they form a can package. The stem base 101 and stem cap 104 are made of, for example, an Fe-based metal material, and the heat sink 102 is made of a metal material that has higher thermal conductivity than the stem base 101, such as copper, gold, or a copper-tungsten alloy. The heat sink 102 may also be made of a ceramic that has higher thermal conductivity than the stem base 101, such as aluminum nitride or silicon carbide.

The stem base 101 corresponds to an example of a base as defined in the present invention, the block portion 102a of the heat sink 102 corresponds to an example of a columnar block as defined in the present invention, the flange portion 102b of the heat sink 102 corresponds to an example of a heat sink as defined in the present invention, and the stem cap 104 corresponds to an example of a cap as defined in the present invention.

A laser chip 103 is indirectly fixed to the block portion 102a of the heat sink 102 via, for example, a submount 103a on a side surface (particularly a flat portion) rising from the upper surface 101a of the stem base 101. The laser chip 103 may be directly bonded to the block portion 102a, but in this embodiment, the submount 103a is used. The laser chip 103 corresponds to an example of a light-emitting element as referred to in the present invention. The light-emitting element as referred to in the present invention may be an LED, but in this embodiment, the laser chip 103 is used.

The light emitting point of the laser chip 103 is located at the center of the stem base 101, which has a circular outer edge shape, and heat generated by the laser chip 103 during light emission is transferred to the block portion 102a. The laser chip 103 may be a multi-emitter type that emits multiple spots of laser beams, but in this embodiment it is described as a single-emitter type that emits a single spot of laser beam. The diameter of the circular stem base 101 is described as φ9 mm in this embodiment, but it may be φ16 mm, φ5.6 mm, φ3.8 mm, etc., and is not limited to φ9 mm.

The cylindrical stem cap 104 has a circular window 104a, into which glass 104b is attached. The laser light emitted from the laser chip 103 passes through the window 104a in the stem cap 104 and exits the stem. The glass is not limited to flat glass, but may be a spherical or aspherical lens. The stem cap 104 has a peripheral portion 104c welded to the upper surface 101a of the stem base 101, thereby hermetically sealing the internal space.

The flange portion 102b of the heat sink 102 contacts the lower surface 101b of the stem base 101 and spreads out, reaching the back surface of the peripheral portion 104c of the stem cap 104 (i.e., the opposite side of the peripheral portion 104c with the stem base 101 in between). When welding the peripheral portion 104c, the contact between the flange portion 102b and the stem base 101 makes welding easier and ensures an airtight seal.

By covering the laser chip 103 with the stem cap 104, the laser chip 103 is protected from damage due to contact with the outside and from adhesion of foreign matter such as dust. In addition, the internal space of the can package is hermetically sealed, preventing deterioration of the laser element due to moisture in the air or adhesion of organic matter, resulting in a highly reliable semiconductor laser device.

The power supply lead pin 105 passes through the second through hole 101d of the stem base 101, and one end of the lead pin 105 protrudes to the inside covered by the stem cap 104, and a wire 106 is connected from the end of the lead pin 105 to the laser chip 103. The laser chip 103 of this embodiment is a high-output laser chip with an optical output of, for example, 1 W or more, and is supplied with a current of, for example, 1 A or more and a voltage of, for example, 2 W or more of power via the multiple wires 106 from one power supply lead pin 105.

When the wire has a diameter of φ20 μm, each wire can withstand about 1 A, but for high-output lasers of the W class, a large current of 1 A or more is usually required, so multiple wires are required. These wires 106 are joined to the power supply lead pins 105.

In this embodiment, two power supply lead pins 105 with different polarities are provided, one of which is connected to one side of the laser chip 103 by a wire 106, and the other is connected to the other side of the laser chip 103 via the submount 103a and the wire 106. These power supply lead pins 105 are fixed to the inner wall of the second through hole 101d by melting and bonding glass 107 to maintain an airtight seal. Since glass 107 is a type of insulating material, the power supply lead pins 105 are fixed to the stem base 101 and insulated by the glass 107.

A through hole 102c through which the power supply lead pin 105 passes is formed in the flange portion 102b of the heat sink 102. The heat sink 102 is separated from the power supply lead pin 105 by the through hole 102c, and the heat sink 102 and the power supply lead pin 105 are insulated from each other.
The heat generated by the laser chip 103 as it emits light is dissipated by the heat sink 102 .
FIG. 2 is a diagram showing how heat is dissipated by the heat sink 102. As shown in FIG.

Heat generated by the laser chip 103 is transferred to the block portion 102a of the heat sink 102 via the submount 103a, and then transferred from the block portion 102a to the flange portion 102b. The flange portion 102b comes into contact with the cooling portion 200 of the external device to which the semiconductor laser device 100 is attached, and dissipates the heat to the cooling portion 200.

The block portion 102a extends straight from the first through hole 101c of the stem base 101, so heat can be transferred quickly from the submount 103a to the flange portion 102b. In addition, the stem base 101 covers the periphery of the block portion 102a, preventing the heat that reaches the flange portion 102b from returning to the inside of the can package.

The flange portion 102b of the heat sink 102 is brazed to the underside 101b of the stem base 101 with brazing material 110, so that the stem base 101 and the flange portion 102b are integrated, ensuring the robustness of the can package.

The block portion 102a of the heat sink 102 is soldered to the inner wall of the first through hole 101c of the stem base 101 with solder material 110, improving the heat dissipation to the flange portion 102b and suppressing the change in the position of the light emitting point of the laser chip 103 due to thermal expansion of the block portion 102a.

In order to obtain high heat dissipation performance by the flange portion 102b, the flange portion 102b is required to have a sufficient area. Here, the area ratio of the flange portion 102b to the total area of the lower surface 101b of the stem base 101 will be considered.
FIG. 3 is a diagram showing the expanding range of the stem base 101 and the expanding range of the flange portion 102b.

Figure 3 shows the top surface of the semiconductor laser device 100 with the cap removed, with the bottom surface 101b of the stem base 101 extending over the same area as the top surface 101a. In Figure 3, the range over which the flange portion 102b extends is shown by a dotted line, with the flange portion 102b extending to the very limit of the edge of the stem base 101 at the outer periphery. In this way, when the flange portion 102b extends to the very limit of the edge of the bottom surface 101b of the stem base 101, the area ratio of the stem base 101 is 80% or more.

In addition, if the flange portion 102b extends to the range of the peripheral portion 104c (see Figure 1) of the stem cap 104, and the diameter of the peripheral portion 104c is 7.25 mm, the area ratio to the stem base 101 is 66.25%.

Considering these area ratios, the area ratio of the flange portion 102b to the stem base 101 (the lower surface 101b) is preferably 65% or more, and more preferably 80% or more. However, if the area ratio of the flange portion 102b is 100% or more, the flange portion 102b will protrude from the stem base 101, which is not preferable in terms of holding the stem base 101.
Next, a semiconductor laser device 150 according to a second embodiment will be described.
FIG. 4 shows a semiconductor laser device 150 according to the second embodiment, and like FIG. 1, FIG. 4A shows a top view, FIG.

The semiconductor laser device 150 of the second embodiment is similar to the semiconductor laser device 100 of the first embodiment (see FIG. 1) except for the difference in the structure of the heat sink 102, so the following description will focus on the differences and omit redundant description.

In the semiconductor laser device 150 of the second embodiment, the heat sink 102 is formed by joining a block portion 102a and a flange portion 102b formed as separate members. The block portion 102a and the flange portion 102b are joined, for example, by soldering. Even when the block portion 102a and the flange portion 102b are formed as separate members in this manner, the block portion 102a protrudes through the first through hole 101c of the stem base 101 into the internal space of the can package, and the flange portion 102b contacts and expands with the lower surface 101b of the stem base 101.

When the block portion 102a and the flange portion 102b are formed as separate members, the shapes of the block portion 102a and the flange portion 102b are simple, making them easy to manufacture.

100, 150...semiconductor laser device, 101...stem base, 101a...upper surface,
101b...lower surface, 101c...first through hole, 101d...second through hole,
102... heat sink, 102a... block portion, 102b... flange portion,
103: laser chip; 103a: submount; 104: stem cap;
104c: peripheral portion; 105: power supply lead pin; 106: wire; 107: glass;
110...Waxing material

Claims (5)

A base extending in a plate shape and having a first through hole penetrating from a front surface to a back surface;
a cap that covers a first surface side of the front and back surfaces of the base and has a periphery welded to the first surface to form an internal space and hermetically seal the internal space;
a columnar block having a thermal conductivity higher than the thermal conductivity of the base, having a columnar shape, penetrating the first through hole in an extension direction of the columnar shape and protruding into the internal space, and having a side surface fitted into the first through hole;
a heat sink having a thermal conductivity higher than that of the base, contacting and spreading to a second surface on the back side of the first surface, reaching a back side of a portion where the peripheral portion is fixed, and being integral with the columnar block or connected to the columnar block;
a light emitting element made of a semiconductor, which is fixed directly or indirectly to a side surface of the pillar block;
Equipped with
The area ratio of the heat sink to the base is 65% or more and less than 100%;
the pillar-shaped block is brazed to an inner wall of the first through hole so as to suppress a change in position of a light-emitting point of the light-emitting element due to thermal expansion of the pillar-shaped block;
The semiconductor light emitting device according to claim 1, wherein the heat sink is brazed to the second surface of the base . The semiconductor light-emitting device according to claim 1, characterized in that the light-emitting element is a laser element. the base has a second through hole separate from the first through hole,
3. The semiconductor light emitting device according to claim 1, further comprising a lead pin passing through the second through hole to supply power to the light emitting element. The semiconductor light-emitting device according to claim 3, characterized in that the lead pin is fixed to the base by melting and bonding an insulating material to form an airtight seal. The semiconductor light-emitting device according to claim 3 or 4, characterized in that the heat sink is not in contact with the lead pins.

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