JP4821343B2 - Submount substrate and light emitting device including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To mount a submount substrate on a surface while making the submount substrate of a material with conductivity, and to improve heat radiation. <P>SOLUTION: The submount substrate 10 is made of the material having conductivity and has a first bent piece 11 and second bent piece 12 that form an L-sectioned shape. The first bent piece 11 has a mounted surface 13 to be mounted on a base substrate 20, and the second bent piece 12 has an element mounted surface 14 where a wiring part for mounting a semiconductor element 30 is formed. Consequently, the submount substrate 10 made of the material having conductivity such as a conductive substrate can be mounted on the surface, and handling property is improved. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a submount substrate used by interposing a semiconductor element when die-bonding to a support substrate or the like, and a light emitting device in which a light emitting element such as a light emitting diode is mounted on the submount substrate.

  A light-emitting device using a semiconductor element as a light-emitting element emits light with a small color, high power efficiency, and vivid colors. In addition, a light emitting element which is a semiconductor element does not have a concern about a broken ball. Further, it has excellent initial driving characteristics and is strong against vibration and repeated on / off lighting. Because of such excellent characteristics, light-emitting devices using semiconductor light-emitting elements such as light-emitting diodes (LEDs) and laser diodes (LDs) are used as various light sources. In particular, a high-luminance blue light-emitting LED using a GaN-based compound semiconductor has been developed, and a white light-emitting device has been realized by utilizing the luminance. In this white light emitting device, a light emitting element that emits blue light is covered with a resin containing a fluorescent material that emits yellow green light to obtain white light.

  In addition to such a light emitting element, a transistor, a thyristor, or the like is used as a semiconductor element for switching applications, power control, and the like. In mounting such a semiconductor element, in order to improve workability, a configuration in which the semiconductor device is once mounted on a submount substrate which is a small substrate and then mounted on a larger support substrate is employed.

In order to increase the output of the semiconductor element, it is necessary to increase the input current. In particular, in response to the demand for higher output in recent years, high-power LEDs have been developed, and on the other hand, a plurality of such semiconductor elements are used in combination. For example, RGB LED chips are arranged in one package. Thus, light emitting elements capable of emitting full color have been developed. As the output of such semiconductor elements is increased or the number of used semiconductor devices is increased, the amount of heat generation is also increasing. In order to prevent the semiconductor element function from deteriorating due to heat generation of the semiconductor element, it is necessary to take some heat dissipation measures.
JP 2002-368280 A

  Conventionally, resins such as glass epoxy, epoxy, polyimide, and BT resin have been used as materials for electronic circuit boards. A glass epoxy substrate or the like can mount a conductive pattern on an insulating glass epoxy surface and can have a multilayer structure. Therefore, wiring can be crossed inside the multilayer structure, which is convenient as a mounting substrate. However, the glass epoxy substrate has the disadvantages of poor thermal conductivity and poor heat dissipation. Therefore, a configuration is known in which a heat sink member, which is a heat radiator made of aluminum, copper, or the like having high thermal conductivity, is connected in a thermally conductive state to dissipate heat to the outside. The heat sink is directly attached to the semiconductor element, and is attached to the semiconductor element via a submount as a buffer material for reducing the thermal expansion difference, and the heat of the semiconductor element is removed by the action of heat conduction.

  However, since these resin material substrates themselves are inferior in thermal conductivity, even if a heat sink member is connected via a heat conductive lead or the like, sufficient heat dissipation cannot be exhibited. In addition, connecting the heat sink member, which is a separate member, to the heat conducting state has a problem that the configuration becomes complicated and man-hours and costs are excessive.

  On the other hand, metal substrates such as Al having excellent thermal conductivity have also been developed. However, since these substrates have conductivity, the wiring itself cannot be crossed, and it is assumed that a multilayer substrate is formed and a through hole is formed. Even if connected, there is a possibility of short-circuiting at the end face, and there is a problem that it is difficult to make a multi-layer like a double-sided board and surface mounting is difficult.

  The present invention has been made in view of such problems. A main object of the present invention is to provide a submount substrate that can be surface-mounted while being made of a material having conductivity, and a light-emitting device including the submount substrate.

In order to achieve the above object, a first submount substrate of the present invention is a submount substrate on which a semiconductor element can be mounted and can be mounted on a support substrate in a state where the semiconductor element is mounted. The mount substrate is made of a conductive material, the submount substrate has a first bent piece and a second bent piece, and the first bent piece and the second bent piece are Are bent and connected, the first bent piece has a mounting surface mounted on the support substrate, and the second bent piece forms a wiring portion for mounting the semiconductor element. An element mounting surface is provided, and the mounting surface and the element mounting surface are positioned on the same surface of the submount substrate before being bent . Thereby, the surface mounting of the submount board | substrate comprised with the material which has electroconductivity, such as an electroconductive board | substrate, becomes possible, and handling property improves.

  In the second submount substrate, the first bent piece and the second bent piece are integrally formed, and the first bent piece and the second bent piece are formed by bending. And a cross-sectional L-shape. Thereby, a submount substrate having an L-shaped cross section can be configured easily and inexpensively.

  Further, in the third submount substrate, the mounting surface and the element mounting surface are located on the same surface of the submount substrate before bending. Accordingly, it is sufficient to use a single-sided substrate as the submount substrate and perform operations such as wiring on the same surface, so that workability can be improved.

The submount substrate is preferably a substrate whose surface is processed smoothly. Thereby, a semiconductor element can be mounted reliably. Further, by making the submount substrate a substrate having excellent thermal conductivity, the submount substrate can be connected to a heat sink or the like in a thermally conductive state to improve heat dissipation, and the semiconductor element can be stably driven. Moreover, while utilizing a metallic conductive substrate as a submount substrate, it is possible surface mounting. In particular, a semiconductor light emitting element such as LED or LED can be used as a semiconductor element, and a submount substrate suitable for mounting these can be provided.

  Furthermore, the fourth submount substrate is a substrate made of Al, Fe, or Cu—W. As a result, it is possible to mount the conductive substrate made of Al, Fe, or Cu-W as a submount substrate.

  Furthermore, the fifth submount substrate further includes a heat sink member connected to the submount substrate in a heat conductive state. As a result, the heat generated in the semiconductor element mounted on the submount substrate can be conducted to the heat sink member via the submount substrate, and heat dissipation can be exhibited especially when the output is increased. Operation is planned.

  Furthermore, the sixth submount substrate is a housing in which the heatsink member places the submount substrate. Thus, the housing itself can function as a heat sink without preparing a separate heat sink, thereby reducing costs and simplifying the configuration.

Furthermore, a seventh light emitting device is a light emitting device including a semiconductor light emitting element, a submount substrate on which the light emitting light emitting element is mounted, and a support substrate for mounting the submount substrate, and the submount substrate is made of aluminum. The aluminum substrate has a first bent piece and a second bent piece, the first bent piece has a mounting surface mounted on the support substrate, and the second bent piece. The piece has an element mounting surface on which a wiring portion for mounting a semiconductor element is formed, and is bent between the first bent piece and the second bent piece to form an L-shaped cross section. The mounting surface and the device mounting surface are configured to be located on the same surface of the submount substrate before being bent . Thereby, the surface mounting of the submount board | substrate comprised with the material which has electroconductivity, such as an electroconductive board | substrate, becomes possible, and handling property improves.

  According to the submount substrate and the light-emitting device including the same of the present invention, surface mounting of the submount substrate made of a conductive material such as a conductive substrate is possible, and handling properties can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a submount substrate for embodying the technical idea of the present invention and a light emitting device including the same, and the present invention is a submount substrate and a light emitting device including the same. Is not specified as below. Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention unless otherwise specified, and are merely explanations. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.
(Embodiment 1)

  1A and 1B show a state where a submount structure in which a semiconductor element 30 is mounted on a submount substrate 10 according to Embodiment 1 of the present invention is further mounted on a support substrate 20. FIG. 1A is a front view, and FIG. 1B is a cross-sectional view taken along line BB in FIG. 1A. The submount substrate 10 shown in these drawings is bent in an L shape in cross section, and the first bent piece 11 and the second bent piece 12 constitute an L shape. The first bent piece 11 has a mounting surface 13 mounted on the support substrate 20, and the second bent piece 12 has an element mounting surface 14 on which a wiring portion for mounting the semiconductor element 30 is formed. is doing. The first bent piece 11 and the second bent piece 12 are formed by bending the substrate, but may be separate members.

  The submount substrate 10 is composed of a member having excellent thermal conductivity, and is preferably a metal substrate. As the metal material, Al, Fe, Cu-W and the like can be used, and among them, an aluminum substrate that is inexpensive and lightweight, and excellent in conductivity and heat dissipation is particularly preferable. An insulating layer 15 is provided on the surface of the submount substrate 10, and a mounting surface 13 and an element mounting surface 14 are formed thereon. By covering with the insulating layer 15, a short circuit due to the conductive submount substrate 10 is prevented.

  A copper heat spreader or the like is soldered to the element mounting surface 14 on which the semiconductor element 30 is mounted. An electronic component such as the semiconductor element 30 is mounted on the element mounting surface 14. For wiring, a wiring pattern 16 such as a copper pattern is extended from the wiring portion to the mounting surface 13.

  Conventionally, in a metal substrate such as Al, since the substrate itself has conductivity, wiring cannot be crossed, which is disadvantageous in terms of circuit configuration. Further, even if a multilayer substrate is configured and connected through through holes, there is a risk of short-circuiting at the end face, making it difficult to make multilayers. For this reason, there was a problem that it could not be a double-sided board and was difficult to mount on the surface. On the other hand, according to the present embodiment, the mounting surface 13 mounted on the support substrate 20 and the element mounting surface 14 on which the semiconductor element 30 is mounted are physically separated. Can be avoided. Further, by bending the aluminum substrate, the element mounting surface 14 is removed from the same surface as the mounting surface 13, and a space for mounting the semiconductor element 30 is secured. In the example of FIG. 1B, the element mounting surface that is substantially orthogonal to the mounting surface 13 is formed by bending the cross-sectional shape of the connecting portion of the first bent piece 11 and the second bent piece 12 into an L shape. 14 is separated from the surface of the support substrate 20 to secure a mounting space for the semiconductor element 30.

  Further, it is preferable that the mounting surface 13 and the element mounting surface 14 be positioned on the same surface of the submount substrate 10 before being bent. Thus, the submount substrate 10 can be a single-sided substrate, and the mounting surface 13 and the element mounting surface 14 are formed on the same surface of the submount substrate 10 on the single-sided substrate, and then the boundary between the mounted surface 13 and the element mounting surface 14 Since it can be mounted on the support substrate 20 by bending at a portion, these operations can be easily performed.

  In the example of FIG. 1B, the bent first bent piece 11 and the second bent piece 12 are formed by drawing or forming an aluminum substrate. When an aluminum substrate is used for the submount substrate 10, it is preferable to smooth the surface in order to reduce the level difference on the substrate surface.

  After mounting the submount substrate 10 on the support substrate 20 in this manner, the submount substrate 10 is connected to a case or a ground so as to be able to conduct heat. Since the housing generally has a large surface area exposed to the outside, it can function as a heat sink. Thus, the housing itself can function as a heat sink without preparing a separate heat sink, thereby reducing costs and simplifying the configuration.

In the present specification, the term “fixed in a state where heat conduction is possible” is used to include not only a state in which the joint surfaces are in direct contact but also a state in which an insulating layer or the like is interposed as required. .
(Semiconductor element 30)

  The semiconductor element 30 may be a semiconductor light emitting element such as an LED or an LD (semiconductor laser). These semiconductor light emitting devices have the advantage that the linearity of the output with respect to the input is good, the efficiency is excellent, and the long life can be used stably. In particular, LEDs are preferable because they are inexpensive and readily available. Further, as the semiconductor light emitting element, a bullet type (lamp type) or the like can be suitably used in addition to the surface mount type (SMD).

Examples of the material of the semiconductor light emitting device include various semiconductors such as BN, SiC, ZnSe, GaN, InGaN, InAlGaN, AlGaN, BAlGaN, and BInAlGaN. Similarly, these elements may contain Si, Zn, or the like as an impurity element to serve as a light emission center. As a material of the light emitting layer, a nitride semiconductor (for example, a nitride semiconductor containing Al or Ga, a nitride semiconductor containing In or Ga, In _X Al _Y Ga _1-XY N (0 <X <1, 0 <Y < 1, X + Y ≦ 1), etc. The semiconductor structure is preferably a homostructure having a MIS junction, PIN junction or pn junction, heterostructure, or double heterostructure. The emission wavelength can be selected in various ways depending on the material and its mixed crystal ratio, and the output can be increased by adopting a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed in a thin film that produces a quantum effect. It can also be improved.

  In the example of FIGS. 1A and 1B, the semiconductor light emitting element is a side view type LED. In this example, the LED chip is fixed to the bottom surface of the reflector 17 having a concave center. By surrounding the periphery of the LED chip with the reflector 17, the light emitted from the side surface of the LED chip is reflected on the upper surface by the reflector 17, thereby increasing the light output and the directivity. The reflector 17 has a through-opening at the central portion and is coated so as to increase the reflection efficiency of the inner surface of the opening. The reflector 17 is mounted as a separate member from the LED chip. You may use the package which arranged.

  Conventionally, the side view type has a problem that it is difficult to increase the output because it is difficult to secure the heat dissipation path of the package itself. In this embodiment, a heat conductive substrate is used as the submount substrate 10. In addition, by securing a heat radiation path, it is possible to cope with high output. As a result, it can be applied to relatively large power elements such as signals, projectors, and large displays. In addition, a secondary effect that contrast can be improved as a strong directivity can be obtained.

  In the above example, the LED chip is provided with an n-electrode and a p-electrode on the same surface side of the substrate, mounted on the submount substrate 10 in a posture with these as the upper surface, and then wired by wire bonding. A flip chip type or a face down type in which the lower surface is mounted with bumps or the like can also be used. Alternatively, a conductive substrate such as a GaN substrate may be used as the growth substrate, and an n electrode and a p electrode may be formed on the opposing surfaces of the growth substrate.

Since the submount substrate 10 thus obtained can form a reliable heat dissipation path using a metal substrate having excellent conductivity and thermal conductivity, the heat dissipation can be greatly improved and a stable operation can be obtained. . Further, the submount substrate 10 is not a double-sided substrate, and the element mounting surface 14 and the mounted surface 13 are formed only on one side, so the area becomes relatively large and is not suitable for miniaturization. There is also an advantage that it has an appropriate strength and is easy to grip during mounting.
(Embodiment 2)

  In order to further improve the heat dissipation of the submount substrate, a heat sink member can be further provided. 2A and 2B show a state where the heat sink member 40 is fixed as the submount substrate 10B according to Embodiment 2 of the present invention. 2A is a front view, and FIG. 2B is a cross-sectional view taken along line BB in FIG. 2A. The submount substrate 10B shown in these drawings uses the same type as the submount substrate 10 shown in FIGS. 1A to 1B, and members having the same reference numerals are the same as those in FIGS. 1A to 1B. Therefore, detailed description is omitted.

  The submount substrate 10B is an opposing surface opposite to the surface on which the mounted surface 13B and the element mounting surface 14B are provided in a state where the first bent piece 11B and the second bent piece 12B are bent. Further, the heat sink member 40 is fixed. The heat sink member 40 is fixed at least on the surface opposite to the element mounting surface 14B so as to be able to conduct heat with the submount substrate 10B. Since the main heat source is the semiconductor element 30B, the heat generated by the semiconductor element 30B can be sublimated by arranging the heat sink member 40 using the space almost on the back side of the element mounting surface 14B on which the semiconductor element 30B is mounted. Since heat can be conducted to the heat sink member 40 via the mount substrate 10B, the heat conduction path can be shortened and the heat radiation effect can be enhanced.

  Further, in the example of FIG. 2B, in addition to the surface opposite to the element mounting surface 14B, the surface opposite to the mounting surface 13B is fixed to the submount substrate 10B in a state capable of conducting heat. Thus, by connecting not at one place but at multiple places, more uniform heat conduction can be achieved, and a more reliable heat radiation effect can be expected.

The heat sink member 40 can be fixed by die bonding or the like. On the upper surface of the submount substrate 10B, an electrode film for die bonding is formed by titanium, platinum, gold, or a multilayer structure combining these. The heat sink member 40 is fixed after performing a mounting operation such as reflow on the element mounting surface 14B.
(Heat sink member 40)

  The heat sink member 40 is made of a metal having excellent thermal conductivity, such as Cu or Al. Further, by providing the radiation fins, the surface area can be increased, the contact area with the air can be increased, and the heat dissipation can be improved. By providing such a heat sink member 40, the heat dissipation is improved. As a result, the semiconductor element 30B can be stably operated even at a high output, and the reliability of the operation can be improved and the life of the element can be extended.

Further, the heat sink member 40 can also be connected to a housing, ground, or the like in the same manner as described above, thereby forming a more reliable heat dissipation path and further improving heat dissipation.
(Modification)

In the example of FIGS. 2A and 2B, the surface of the submount substrate 10B is covered with the insulating layer 15B as in FIGS. 1A and 1B. However, it is also possible to remove the insulating layer 15B partially, fix the semiconductor element 30B directly on the submount substrate, and conduct these. For example, in the example of FIGS. 3A and 3B, the insulating layer 15C on the mounting surface of the semiconductor element 30C, which is an LED chip, is partially removed and exposed, and is directly bonded onto the aluminum submount substrate 10C. By not interposing an insulating layer between them, the heat conductivity with the heat sink member 40C in this part is improved, and further heat dissipation is achieved. In contrast to the above example, the lower surface of the LED chip is intentionally connected to the aluminum substrate, and the submount substrate 10C can be used for wiring.
(Embodiment 3)

  In the above example, only one chip is mounted as a semiconductor element. However, a plurality of semiconductor elements can be mounted on a submount substrate. FIGS. 4A and 4B show an example of a light emitting device capable of emitting full color light by combining LED light emitting elements as a third embodiment of the present invention. As described above, in the embodiment in which a plurality of semiconductor elements 30D are mounted on one submount substrate 10D and the amount of heat generated increases according to the number of semiconductor elements 30D used, the heat sink member 40D or the like improves heat dissipation. This form can be suitably applied.

4A and 4B, the wiring pattern 16D is made of silver or the like in order to electrically connect the terminals of the LED chips to the submount substrate 10D. A wiring portion is also formed on the element mounting surface on the submount substrate 10D according to the wiring pattern 16D. In this example, five terminals are formed as the wiring pattern 16D, and the left and right are respectively connected to the cathode, and the center three are connected to the RGB anodes.
(Modification)

  Further, in this example as well, the semiconductor element can be directly bonded onto the submount substrate by removing a part of the insulating layer coated on the surface of the submount substrate, as in FIG. In particular, since the amount of heat generation increases as the number of semiconductor elements used increases, it is meaningful to increase the number of semiconductor elements that are directly connected to the submount substrate to further improve the heat conduction. 5A and 5B show an example of a submount substrate 10E that performs such direct bonding. By direct bonding, heat can be efficiently radiated from the heat sink member 40E.

  In the above example, the configuration in which the cross-sectional shape of the connecting portion between the first bent piece and the second bent piece is L-shaped has been described. However, the present invention is not limited to such an L-shaped cross section, and a submount substrate 10V having a V-shaped cross section as shown in FIG. 6 or a sub-mount substrate having a U-shaped (or U-shaped) cross section as shown in FIG. The mounting substrate 10U can also be used. In this way, if the mounting surface and the device mounting surface are formed on the same surface of the submount substrate, and the device mounting surface can be removed from the horizontal surface of the mounted surface by bending the submount substrate, the surface Implementation is possible. Therefore, the present invention does not limit the cross-section of the submount substrate to an L shape, and other shapes can be used as appropriate. Furthermore, not only the structure which bends one submount board | substrate but forms the 1st bending piece and the 2nd bending piece, these are comprised by another member, welding, adhesion | attachment, screwing, etc. Even in the configuration in which these are connected, similarly, the surface to be mounted can be mounted while physically separating the mounting surface and the element mounting surface, so that they can be appropriately employed.

  In the above, an example of a submount substrate on which an LED is mounted as a semiconductor element has been described. However, the present invention is not limited to such a semiconductor light emitting element, and other elements such as a light receiving element such as a photodiode, a switching element such as a transistor and a thyristor, etc. The present invention can also be applied to these semiconductor elements. In particular, it is possible to effectively improve the heat dissipation and stably operate a power semiconductor element having a large amount of heat generation to extend its life.

  The submount substrate of the present invention and the light emitting device including the same can be suitably used for relatively large power elements such as signals and projectors.

1A is a front view showing a state in which a submount substrate according to Embodiment 1 of the present invention is mounted on a support substrate, and FIG. 1B is a cross-sectional view taken along line BB in FIG. 1A. 2A is a front view showing a submount substrate according to Embodiment 2 of the present invention, and FIG. 2B is a cross-sectional view taken along line BB in FIG. 2A. 3A is a front view showing a modification of the submount substrate shown in FIG. 2A, and FIG. 3B is a cross-sectional view taken along line BB of FIG. 3A. 4A is a front view showing a submount substrate according to Embodiment 3 of the present invention, and FIG. 4B is a cross-sectional view taken along line BB in FIG. 4A. 5A is a front view showing a modification of the submount substrate shown in FIG. 4A, and FIG. 5B is a cross-sectional view taken along line BB of FIG. 5A. It is sectional drawing which shows the modification of the submount board | substrate which concerns on another modification. It is sectional drawing which shows the modification of the submount board | substrate which concerns on another modification.

10, 10B, 10C, 10D, 10E, 10V, 10U ... Submount substrate 11, 11B ... First bent piece 12, 12B ... Second bent piece 13, 13B ... Mounted surface 14, 14B ... Element mounted Surface 15, 15B, 15C ... Insulating layer 16, 16D ... Wiring pattern 17 ... Reflector 20 ... Support substrate 30, 30B, 30C, 30D ... Semiconductor element 40, 40C, 40D, 40E ... Heat sink member

Claims (7)

A submount substrate that can be mounted on a support substrate in a state where the semiconductor element can be mounted and the semiconductor element is mounted,
The submount substrate is made of a conductive material,
The submount substrate has a first bent piece and a second bent piece, and the first bent piece and the second bent piece are bent and connected,
The first bent piece has a mounting surface to be mounted on the support substrate;
The second bent piece has an element mounting surface on which a wiring portion for mounting a semiconductor element is formed ;
The submount substrate is configured such that the mounting surface and the element mounting surface are positioned on the same surface of the submount substrate before being bent . The submount substrate according to claim 1,
The first bent piece and the second bent piece are integrally formed, and the first bent piece and the second bent piece form an L-shaped cross section by bending. A submount substrate characterized by comprising: The submount substrate according to claim 2,
The submount substrate, wherein the mounting surface and the device mounting surface are located on the same surface of the submount substrate before bending. A submount substrate according to any one of claims 1 to 3 ,
The submount substrate is a substrate made of Al, Fe or Cu-W. A submount substrate as claimed in any one of 4, the submount substrate, characterized in that it further comprises the sub-mount substrate and the thermally conductive heat sink connected member state. A submount substrate according to any one of claims 1 to 5 ,
A submount substrate, wherein the heat sink member is a casing on which the submount substrate is placed. A semiconductor light emitting device;
A submount substrate on which the light emitting element is mounted;
A support substrate for mounting the submount substrate;
A light emitting device comprising:
The submount substrate is made of an aluminum substrate;
The aluminum substrate has a first bent piece and a second bent piece,
The first bent piece has a mounting surface to be mounted on a support substrate;
The second bent piece has an element mounting surface on which a wiring portion for mounting a semiconductor element is formed,
The first bent piece and the second bent piece are bent to form a cross section in an L shape ,
The light emitting device, wherein the mounting surface and the element mounting surface are configured to be positioned on the same surface of the submount substrate before being bent .

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