JP2013120824A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device capable of always exerting target heat dissipation properties even when mounted at a position deviated from a targetted mounting position of a light-emitting element.SOLUTION: The light-emitting device comprises: a light-emitting element having a semiconductor layer on one surface of a substrate; and a mounting substrate which fixes the other surface of the substrate to a surface via an insulating adhesive. Recesses and protrusions are provided on the other surface of the substrate. An insulating adhesive is filled in a plurality of recesses of the recesses and protrusions. The light-emitting element is mounted on the mounting substrate with the plurality of protrusions contacting with the mounting substrate.

Description

  The present invention relates to a light emitting device.

  A light-emitting device in which a light-emitting element is mounted on a mounting substrate using an insulating adhesive is known (for example, see Patent Document 1).

  A conventional light emitting device 101 shown in FIG. 9 is configured by mounting the light emitting element 102 on a mounting substrate (lead frame) 111a having a concavo-convex portion 105 (concave portion 105a, convex portion 105b) on a mounting surface.

  The light-emitting element 102 has a structure in which a semiconductor layer 104 is provided on one surface of a flat sapphire substrate 103, and the projection 105 b of the mounting substrate 111 a is in contact with the other surface of the substrate 103. It is fixed to the mounting substrate 111a by the adhesive 113. At this time, the insulating adhesive 113 not only enters the recess 105a but also reaches the outer periphery of the substrate 103, and fixes the light emitting element 102 to the mounting substrate 111a.

  In addition, the semiconductor layer 104 and the mounting substrates 111a and 111b are electrically connected by two bonding wires 121, and current is supplied to the semiconductor layer 104 through the mounting substrates 111a and 111b and the bonding wires 121. Then, the semiconductor layer 104 is caused to emit light, and light is emitted in the direction of the arrow in the figure.

JP 11-26811 A (page 3-4, FIG. 1)

  However, the following problems occur when an attempt is made to realize a conventional configuration using a small element having an outer size of the light emitting element 102 of, for example, about 200 μm × 200 μm. The problem will be described with reference to FIG.

  In this conventional light emitting device 101, as shown in FIG. 10 (a), a concave and convex portion 105 having a pitch of 40 μm, for example, is formed only on the surface area (mounting position A) of the mounting substrate 111a on which the light emitting element 102 is mounted. Then, the insulating adhesive 113 is applied to the surface of the substrate so as to cover the mounting position A, and then the light-emitting element 102 is mounted face-up on the target mounting position A using a chip mounter device.

  However, as shown in FIG. 10B, the mounting position when using a general chip mounter device is only a deviation amount B (several tens of μm) from the target position (mounting position A). In some cases, it will be shifted to the left. As described above, when the light emitting element 102 is mounted out of the target position, there is a convex portion (the convex portion 105b at the right end in the drawing) that does not contact the sapphire substrate 103. That is, in the case shown in this drawing, the contact area between the convex portion 105b and the mounting substrate 111a is about ¾ compared to when it is normally mounted, and the heat generated in the light emitting element 102 is applied to the mounting substrate 111a. Reduces thermal conductivity. Due to this decrease in thermal conductivity, the junction temperature of the light emitting element 102 is increased, which causes a problem that the heat dissipation characteristics of the light emitting element 102 are deteriorated.

  Accordingly, an object of the present invention is to solve the above-described problems and to provide a light-emitting device that can always exhibit the desired heat dissipation even when the light-emitting element is mounted out of the target mounting position.

  The light emitting device of the present invention basically adopts the following configuration.

  A light-emitting device of the present invention includes a light-emitting element having a semiconductor layer on one surface of a substrate, and a mounting substrate that fixes the other surface of the substrate to the surface via an insulating adhesive. The light-emitting element is mounted on the mounting substrate in a state where the surface has an uneven portion, a plurality of concave portions in the uneven portion are filled with an insulating adhesive, and the plurality of convex portions are in contact with the mounting substrate. Is.

  Further, in the light emitting device of the present invention, the plurality of recesses are grooves arranged radially from the center of the other surface of the substrate toward the outer periphery, a plurality of linear grooves arranged at a predetermined interval, or a plurality of grooves. Desirably, the grooves are formed with the protrusions left behind.

  In the light emitting device of the present invention, a plurality of linear grooves or a plurality of protrusions may be arranged at unequal intervals.

  In the light emitting device of the present invention, the depth of the recess may be shallow at the center of the substrate and deep at the outer periphery of the substrate.

  By adopting the configuration of the light emitting device of the present invention described above, even when the mounting position is greatly deviated from the target position when mounting the light emitting element on the mounting substrate with the chip mounter, the initial target heat dissipation performance is achieved. A light-emitting device that can always be exhibited can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is drawing which shows the structural example of the light-emitting device in Embodiment 1 of this invention, A sectional view is shown to Fig. (A), and the lower top view of a light emitting element is shown to Fig. (B). It is drawing for demonstrating thermal conductivity when the light-emitting device in Embodiment 1 of this invention is light-emitted. It is drawing for demonstrating the characteristic of the light-emitting device in Embodiment 1 of this invention. It is process sectional drawing which shows the manufacturing method of the light emitting device in Embodiment 1 of this invention. It is process sectional drawing which shows the manufacturing method of a continuation of FIG. 4A. It is process sectional drawing which shows the manufacturing method of the continuation of FIG. 4B. It is (a) front view of the modification 1 of the light emitting element in Embodiment 1 of this invention, (b) The left view, (c) It is a bottom view. It is sectional drawing which shows the modification 2 and the modification 3 in Embodiment 1 of this invention. It is sectional drawing which shows the structural example in Embodiment 2 of this invention. It is a bottom view of the light emitting element which shows the structural example in Embodiment 3 of this invention. It is sectional drawing which shows the structure of the conventional light-emitting device. It is a cross section which shows the problem of the conventional light-emitting device.

[Description of Configuration Example of Embodiment 1]
A configuration example according to the first embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1A, the light emitting device 1 is configured by applying an insulating adhesive 13 to a mounting position on the surface of a flat mounting substrate 11 and then mounting the light emitting element 2 face up. .

  The light-emitting element 2 has a blue surface in which a semiconductor layer 4 in which an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer are sequentially stacked, for example, of a GaN-based semiconductor material is disposed on one surface of a substrate 3 made of sapphire or GaN. Light emitting diode or near ultraviolet light emitting diode.

  In addition, as shown in FIGS. 1A and 1B, the light-emitting element 2 has a plurality of recesses 5a (grooves) formed on the other surface of the substrate 3 at a predetermined interval (equal intervals in this figure). And the concavo-convex portion 5 including the convex portion 5b. An insulating adhesive 13 for fixing the light emitting element 2 to the mounting substrate 11 is filled in the plurality of concave portions 5 a in the concave and convex portion 5, and the plurality of convex portions 5 b are directly on the surface of the mounting substrate 11. In the state of contact, the substrate 3 of the light emitting element 2 and the mounting substrate 11 are bonded and fixed. At this time, the insulating adhesive 13 not only fills the recess 5a but also wraps around the outer periphery of the element to increase the contact area. In this way, the concave portions 5a and the convex portions 5b of the concavo-convex portion 5 are repeatedly formed at equal intervals in the drawing, and are formed into the concave portions 5a at the edge portions on both sides of the substrate. The insulating adhesive 13 filled in the recess 5a and the operation and arrangement of the uneven portion 5 will be described later.

  As the insulating adhesive 13 used here, a die bond material for photo devices (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name KER-3000-M2), which is a silicone-based thermosetting resin, is used. Here, when the light emitting element 2 is mounted on the mounting substrate 11, as the highly fluid insulating adhesive 13, for example, an adhesive whose viscosity is reduced to 10 [Pa · s] is used.

  The mounting substrate 11 is made of a substrate in which an insulating layer such as alumite or silicon oxide is partially formed on the surface of a metal plate such as copper or aluminum, and a wiring pattern 12 is disposed thereon, or aluminum nitride or alumina. A substrate in which a wiring pattern 12 made of copper is formed on an insulating substrate such as ceramics or a glass epoxy substrate can be used. Furthermore, a white organic or inorganic insulator (not shown) may be provided in the entire area except the surface of the wiring pattern 12 that is electrically connected to the light emitting element 2 on the surface of the mounting substrate 11.

Further, a p electrode and an n electrode (not shown) on the surface of the semiconductor layer 4 of the light emitting element 2 and the wiring pattern 12 formed on the surface of the mounting substrate 11 are electrically connected by a bonding wire 21 made of gold or silver. Further, the whole is covered with a sealing resin 23 including a phosphor 22 and made of a thermosetting silicone resin. The phosphor 22 used here is, for example, an yttrium aluminum garnet (YAG) phosphor, which is a light emitting device with a mixture of blue light (primary light) and excitation light (secondary light) emitted from a blue light emitting diode. 1 emits white light.
[Description of Operation of Embodiment 1]
Next, the operation of the uneven portion 5 formed on the other surface of the substrate 3 will be described with reference to FIG.

  As shown in FIG. 2, the light emitting element 2 supplies current to the semiconductor layer 4 through the wiring pattern 12 and the bonding wire 21, so that the semiconductor layer 4 emits light and emits light mainly in the direction of the arrow. .

At this time, the heat generated in the semiconductor layer 4 is mainly conducted through the convex portion 5b formed on the other surface of the substrate 3 to the mounting substrate 11 in direct contact with the convex portion 5b, and is radiated to the outside. Is done. Here, when “sapphire” is used for the substrate 3, “copper plate” is used for the mounting substrate 11, and the above “(trade name) KER-3000-M2” is used for the insulating adhesive, the thermal conductivity of sapphire is 25 [W / m · K],
The heat conductivity of copper of the mounting substrate is 398 [W / m · K], and the heat conductivity of the insulating adhesive is 0.26 [W / m · K]. That is, since sapphire has a thermal conductivity about 1000 times higher than that of the adhesive, according to the configuration of the present embodiment, most of the heat generated in the semiconductor layer 4 is higher than the route L of the insulating adhesive 13. The heat is transmitted to the mounting substrate 11 via the route H of the convex portion 5b made of sapphire and is radiated to the outside.

  As described above, the light emitting device 1 of the first embodiment having high heat dissipation performance prevents the temperature of the light emitting element 2 from becoming excessively high, increases the input power to the light emitting element 2, and increases the output. Can be achieved. Moreover, the junction temperature of the light emitting element 2 can be lowered by lowering the thermal resistance between the light emitting element 2 and the mounting substrate 11 using this means. As a result, the thermal deterioration of the sealing resin 23 is suppressed as much as possible, and the effect of extending the life of the light emitting device 1 is obtained.

  Here, the reason why the problem occurring in the conventional configuration is solved in the light emitting device 1 of the first embodiment will be described with reference to FIG. 3A shows a state in which the light emitting element 2 is normally mounted at the target mounting position A, and FIG. 3B shows a state in which the light emitting element 2 is shifted from the target mounting position A by a shift amount B. Indicates the state of being implemented. In the following description, the light-emitting element 2 is a small element having an outer size of about 200 μm × 200 μm, and the uneven pitch is 40 μm (recess width 20 μm, protrusion width 20 μm).

  As shown in FIG. 3A, the light-emitting element 2 having the concavo-convex portion 5 on the other surface of the substrate 3 is mounted on the mounting substrate 11 coated with the insulating adhesive 13 at the mounting position A using a chip mounter device. Then, face up to the mounting position A. At this time, since the concave and convex portion 5 has the concave portions 5a and the convex portions 5b alternately arranged so that both edges of the substrate 3 become the concave portions 5a, the insulating adhesive 13 is filled in the concave portion 5a. The insulating adhesive 13 wraps around the outer periphery of the substrate 3, and the light emitting element 2 and the mounting substrate 11 can be reliably fixed.

  Here, as shown in FIG. 3B, even if the light emitting element 2 is shifted from the target mounting position A in the left direction by a shift amount B (several tens of μm), the insulating adhesive 13 and the substrate 3 Although the contact area between the four protrusions 5b is all in direct contact with the mounting substrate 11, it can be seen that the thermal conductivity is not different from that in FIG.

As described above, in the conventional configuration, the heat radiation performance varies depending on the individual light emitting devices due to the mounting position shift of the chip mounter device. Thus, it is possible to solve the problem that has occurred in the conventional configuration and to provide the light emitting device 1 that always has stable heat dissipation performance.
[Description of Manufacturing Method of Embodiment 1]
Next, the manufacturing method of the light-emitting device 1 of Embodiment 1 will be described with reference to FIGS. 4A to 4C.

  First, as shown in FIG. 4A (2), the uneven portion 5 is formed on the back surface side of the large sapphire substrate 3a shown in FIG. 4A (1). The substrate processing here uses a well-known method such as laser processing, blast processing, etching, or the like to form a target uneven pitch (40 μm pitch) to obtain the substrate 3b.

  Next, as shown in FIG. 4A (3), a semiconductor layer 4 including a buffer layer, an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer is sequentially formed on the surface of the substrate 3b by MOCVD. Subsequently, although not shown, after part of the p layer is scraped to expose the surface of the n layer, a p electrode, an n electrode, and a protective film exposing each electrode are formed. And it isolate | separates into an element unit in the position 6, and obtains the single light emitting element 2 shown to FIG. 4A (4).

  Next, as shown in FIG. 4B (5), a silicone-based thermosetting resin (trade name) is prepared from a nozzle 31 of a potting device at a central portion of the mounting substrate 11 having the wiring pattern 12 prepared in advance. The insulating adhesive 13 having a KER-3000-M2 (viscosity of 10 [Pa · s]) is applied.

  Next, as shown in FIGS. 4B (6) and 7 (7), the light-emitting element 2 is mounted face-up in accordance with the target mounting position of the mounting substrate 11 using a chip mounter device. At this time, in order not to shift the position of the light emitting element 2, the temperature is increased at 100 ° C. for 1 hour and further to 150 ° C. while being pressed from the upper part of the element, and then the insulating adhesive 13 is cured for 2 hours. Then, after the fixing of the light emitting element 2 to the mounting substrate 11 is completed, the pressure on the element is released. By pressing the element, the insulating adhesive 13 is filled into the concave portion 5a, and the insulating adhesive 13 is passed to the side surface of the substrate 3, so that the contact area between the resin and the substrate is increased as much as possible. Secure to.

Next, as shown in FIG. 4C (8), the electrode of the semiconductor layer 4 and the wiring pattern 12 are electrically connected by the bonding wire 21 using a bonding apparatus, and finally, as shown in FIG. 4C (9). Thus, the light emitting device 1 of Embodiment 1 is completed by covering the entire surface of the mounting substrate 11 with the sealing resin 23 made of a thermosetting silicone resin including the phosphor 22.
[Description of Configuration and Action of Modification 1]
Next, the configuration and operation of Modification 1 of the light-emitting element 2 in Embodiment 1 will be described with reference to FIG. 5A is a front view of the light emitting element 2, FIG. 5B is a left side view, and FIG. 5C is a bottom view.

  As shown in FIG. 5, in the light emitting element 2 of the first modification, the groove depth of the plurality of recesses 5a formed on the other surface of the substrate 3 is shallow at the center of the substrate and gradually becomes deeper toward the outside. I am doing so. Other forms are the same as those described above.

As described above, by forming the groove depth outside the center into a deep concave shape, the element outer side of the insulating adhesive 13 in the steps shown in FIGS. 4B (6) and (7) (light emitting element mounting step) described above. Is surely secured due to the low thermal resistance between the convex portion 5b and the mounting substrate 11.
[Description of Configuration and Action of Modification 2 and Modification 3]
Next, the configuration and operation of the light-emitting element 2 in Modification 2 and Modification 3 will be described with reference to FIG. FIG. 6A shows the configuration of the second modification, and FIG. 6B shows the configuration of the third modification.

  Although FIG. 1B shows an example in which the arrangement of the concave portions 5a and the convex portions 5b is equally spaced, in the second modification (FIG. 6A), the interval between the concave portions 5a-1 at the center is increased. The width of the concave portion 5a-2 located on the outer side and the outer concave portion 5a-3 are gradually reduced. In Modification 3 (FIG. 6B), the depth of the concave portion 5a-1 at the center is the shallowest, and the concave portion 5a-2 and further the concave portion 5a-3 are gradually deepened. I have to.

  According to the configurations of Modification 2 and Modification 3, in addition to the above-described characteristics of the heat dissipation performance of the present invention, mounting is performed in the process of FIG. 4B (5) (potting process of the insulating adhesive 13 on the mounting substrate 11). Even if many insulating adhesives 13 are potted in the center of the substrate 11, when the light emitting element 2 is pressed against the mounting substrate 11 in the step of FIG. .

[Description of Configuration Example of Embodiment 2]
Next, a configuration example and operation of the light-emitting element 2 of Embodiment 2 will be described with reference to FIG.

  As shown in FIG. 7, in the light-emitting element 2 of Embodiment 2, the cross-sectional shape of the concavo-convex portion 5 on the other surface of the substrate 3 is a wedge shape. Others are the same as the configuration example shown in the previous embodiment.

  By adopting the configuration of the second embodiment, the contact area between the light-emitting element 2 and the mounting substrate 11 is lower than that of the configuration example shown in the first embodiment. However, FIG. 4B (6) (7) steps (light-emitting element) In the mounting process), the insulating adhesive 13 can be more easily pushed to the outside of the element. That is, in the configuration example of the previous embodiment, it was necessary to use a low-viscosity material for the insulating adhesive 13, but in the case of this modification, even a relatively high-viscosity material is reliably used. There is an advantage that the element and the mounting substrate 11 can be contacted. Furthermore, by applying a device for the groove depth and width of the recess 5a as in the first and second modifications, the insulating adhesive 13 can be further pushed out more easily.

[Description of Configuration of Configuration Example 1 to Configuration Example 4 of Embodiment 3]
Next, structural examples 1 to 4 of the light-emitting element 2 of Embodiment 3 will be described with reference to FIG.

  In the configuration example 1 shown in FIG. 8A, a plurality of convex portions 5b (protrusions) arranged at equal intervals are provided, and another region where the protrusions are left is defined as a concave portion 5a. The plurality of protrusions are not necessarily arranged at regular intervals, and the arrangement form can be changed as necessary.

  Further, in FIG. 8B, the recesses 5a composed of a plurality of grooves are arranged radially from the center to the outer periphery of the substrate 3, and in FIG. 8C, the width of the recesses 5a composed of the radial grooves. However, it gradually widens from the center toward the outer periphery. Further, in FIG. 8D, a plurality of the groove patterns in FIG. 8B are arranged.

  With the above configuration, as described above, the insulating adhesive 13 inside the recess 5a is filled in the process of FIG. 4B (6) and (7) (light emitting element mounting process), and the element is wrapped around the element. Thus, not only the mounting substrate 11 and the light emitting element 2 are securely fixed, but also the projection 5b and the mounting substrate 11 are in direct contact with each other, and heat generated in the light emitting element 2 is efficiently transmitted to the mounting substrate 11. be able to. Note that the configurations of the first to third modifications of the first embodiment can be further combined to make it easier to push the insulating resin 13 to the outer periphery of the element in the steps of FIGS. 4B (6) and (7).

DESCRIPTION OF SYMBOLS 1 Light emitting device 2 Light emitting element 3 Substrate 4 Semiconductor layer 5 Concave part 5a, 5a-1 to 5a-3 Concave part 5b Convex part 6 Position 11 Mounting board 12 Wiring pattern 13 Insulating adhesive 21 Bonding wire 22 Phosphor 23 Sealing resin 31 nozzles

Claims (5)

A light-emitting element having a semiconductor layer on one surface of the substrate;
A mounting substrate for fixing the other surface of the substrate to the surface via an insulating adhesive; and
The other surface of the substrate has an uneven portion,
The light emitting device is mounted on the mounting substrate in a state where the insulating adhesive is filled in a plurality of concave portions in the concave and convex portions, and the plurality of convex portions are in contact with the mounting substrate. The light emitting device according to claim 1, wherein the plurality of recesses are grooves arranged radially from the center of the other surface of the substrate toward the outer periphery. 2. The light emitting device according to claim 1, wherein the plurality of recesses are a plurality of linear grooves arranged at a predetermined interval or a groove formed by leaving a plurality of protrusions. The light emitting device according to claim 3, wherein the plurality of linear grooves or the plurality of protrusions are arranged at unequal intervals. 5. The light emitting device according to claim 2, wherein a depth of the concave portion is shallow at a central portion of the substrate and deep at an outer peripheral portion of the substrate.

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