JP2009054897A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device capable of preventing LED chips from short-circuiting to each other due to solder while making intervals between adjacent LED chips narrow. <P>SOLUTION: The submount member 30 (mounted member) has a plurality of island-shaped chip mount portions 30b where conductor patterns 31 to which respective LED chips 10 are individually soldered are formed, and the plane size of a tip surface of each chip mount portion 30b is set smaller than the plane size of each LED chip 10. When an LED chip 10 is joined to a conductor pattern 31 of each chip mount portion 30b, a process of self-alignment wherein a suitable amount of solder is applied onto the conductor pattern 31 and then the LED chip 10 is positioned by using the surface tension of the solder is employed to enhance positioning precision of the LED chip 10 and also solder is prevented from projecting from a thickness-directional projection area of the LED chip 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light emitting device using an LED chip (light emitting diode chip).

Conventionally, a light emitting device in which a plurality of LED chips are mounted on one mounted member (for example, a submount member, a circuit board, etc.) has been proposed (for example, see Patent Document 1).
JP 2006-502567 A (paragraph [0032] and FIGS. 3 and 4)

  However, in the light emitting device disclosed in Patent Document 1, when the LED chip and the conductor pattern provided on the mounted member are joined by solder, the projection in the thickness direction of the LED chip is performed by applying an appropriate load. There is a possibility that the adjacent LED chips are short-circuited by the solder protruding from the region, and the LED chips may be displaced due to the application of a load.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a light emitting device capable of preventing a short circuit between LED chips due to solder while narrowing the interval between adjacent LED chips. .

  The invention of claim 1 includes a plurality of LED chips and a single mounted member formed of an insulating material and mounted with the plurality of LED chips, and the mounted member includes each LED chip separately. It has a plurality of island-shaped chip mounting portions on which conductor patterns to be joined by solder are formed, and the planar size of the tip surface of the chip mounting portion is set smaller than the planar size of the LED chip. .

  According to the present invention, the mounted member has a plurality of island-shaped chip mounting portions each having a conductor pattern on which each LED chip is joined by solder, and the planar size of the tip surface of the chip mounting portion is Since it is set smaller than the planar size of the LED chip, when bonding the LED chip to the conductor pattern of each chip mounting portion, after applying an appropriate amount of solder on the conductor pattern, using the surface tension of the solder Adopting the process of positioning the LED chip can increase the positioning accuracy of the LED chip and can prevent the solder from protruding from within the projection area in the thickness direction of the LED chip. It is possible to prevent a short circuit between the LED chips due to soldering while narrowing the interval between them.

  According to the first aspect of the present invention, there is an effect that it is possible to prevent a short circuit between the LED chips due to the solder while narrowing the interval between the adjacent LED chips.

  Hereinafter, the light-emitting device of this embodiment will be described with reference to FIGS.

  The light emitting device 1 of the present embodiment includes a plurality (9 in the present embodiment) of LED chips 10 and a conductive pattern 23 for feeding power to the series circuit of the plurality of LED chips 10 described above on one surface side. 23, each LED chip 10 is mounted on the one surface side of the rectangular plate-like mounting substrate 20, and an optical member for controlling the light distribution of the light emitted from each LED chip 10, The LED chip 10 is housed between the dome-shaped optical member 60 made of a translucent material fixed to the one surface side of the mounting substrate 20, and the optical member 60 and the mounting substrate 20. A sealing portion 50 made of a sealing resin that seals each LED chip 10 and a bonding wire (not shown) electrically connected to each LED chip 10 in a space, LED chip 10 It is formed by a phosphor and a translucent material that is excited by light emitted and transmitted through the sealing portion 50 and the optical member 60 and emits light of a color different from the emission color of each LED chip 10 and mounted. A dome-shaped color conversion member 70 is provided on the one surface side of the substrate 20 so as to surround each LED chip 10 between the mounting substrate 20 and the like. Here, the color conversion member 70 is disposed so that an air layer 80 is formed between the light emitting surface 60 b of the optical member 60 on the one surface side of the mounting substrate 20. Further, the mounting substrate 20 has an annular dam portion 27 protruding outside the optical member 60 on the one surface so as to dam the sealing resin overflowing from the space when the optical member 60 is fixed to the mounting substrate 20. Has been.

  In addition, the light emitting device 1 according to the present embodiment includes a resin that includes a filler made of a filler such as silica or alumina on the other surface side of the mounting substrate 20 as a sheet-like bonding member 90 and has a low viscosity when heated. A sheet (for example, an organic green sheet such as an epoxy resin sheet highly filled with fused silica) is provided. Thus, when the light-emitting device 1 of the present embodiment is used as a light source of a lighting fixture, for example, a fixture main body 100 made of metal (for example, a metal having high thermal conductivity such as Al or Cu) in the lighting fixture (FIG. 2). And the mounting substrate 20 can be joined by the joining member 90. Here, since the bonding member 90 made of the resin sheet has electrical insulation properties, heat conductivity is high, fluidity at the time of heating is high, and adhesion to the uneven surface is high, the mounting substrate 20 is made of a metal instrument. Joining to the main body 100 via the joining member 90 (the joining member 90 is heated between the mounting substrate 20 and the instrument main body 100 and then the joining member 90 is heated to thereby heat the mounting substrate 20 and the instrument main body 100. Can be prevented from generating gaps between the bonding member 90 and the mounting substrate 20 and the instrument main body 100, thereby preventing an increase in thermal resistance and variations due to insufficient adhesion. Compared to the conventional case where the light emitting device is mounted on a circuit board and a rubber sheet-like heat radiation sheet such as Sarcon (registered trademark) is sandwiched between the circuit board and the instrument body, the LED chip is used. Since the heat resistance from 10 to the instrument body 100 can be reduced to improve heat dissipation and the variation in thermal resistance is reduced, and the temperature rise of the junction temperature of the LED chip 10 can be suppressed, the input power can be increased, High output power can be achieved. In addition, when using the light-emitting device 1 of this embodiment as a light source of a lighting fixture, a plurality of light-emitting devices 1 are mounted on the fixture body 100 and the plurality of light-emitting devices 1 are connected in series or in parallel. That's fine.

  The LED chip 10 is a GaN blue LED chip that emits blue light, and has an anode electrode (not shown) and a cathode electrode (not shown) on one surface side (upper surface side in FIGS. 1A and 1B). ) Is formed.

  The mounting substrate 20 is made of a thermally conductive material, and has a rectangular submount member 30 on which the LED chip 10 is mounted, a rectangular plate-shaped heat transfer plate 21 on which the submount member 30 is mounted, and heat transfer. A wiring board comprising a rectangular flexible printed wiring board fixed to one surface side of the board 21 (the upper surface side in FIGS. 1A and 1B) via, for example, a polyolefin-based fixing sheet 29 (see FIG. 2). And a rectangular window hole 24 that exposes the mounting surface (a part of the one surface) of the submount member 30 in the heat transfer plate 21 is formed at the center of the wiring board 22. 10 is mounted on a submount member 30 disposed inside the window hole 24. Therefore, heat generated in each LED chip 10 is transferred to the submount member 30 and the heat transfer plate 21 without passing through the wiring board 22. Here, an alignment mark 21 c for increasing the positioning accuracy of the submount member 30 is formed on the one surface of the heat transfer plate 21. In this embodiment, Cu is adopted as the heat conductive material of the heat transfer plate 21, but not limited to Cu, for example, Al may be adopted.

  The wiring board 22 is provided with a pair of conductor patterns 23 and 23 for feeding power to the series circuit of the plurality of LED chips 10 on one surface side of the insulating base material 22a made of a polyimide film. A protective layer 26 made of a white resist (resin) is laminated to cover each conductor pattern 23, 23 and the insulating substrate 22 a where the conductor pattern 23, 23 is not formed. Therefore, the light emitted from the side surface of each LED chip 10 and incident on the surface of the protective layer 26 is reflected by the surface of the protective layer 26, so that the light emitted from each LED chip 10 is absorbed by the wiring board 22. The light output can be improved by improving the light extraction efficiency to the outside. In addition, each conductor pattern 23 and 23 is formed in the outer periphery shape a little smaller than half of the outer periphery shape of the insulating base material 22a. Further, FR4, FR5, paper phenol or the like may be employed as the material of the insulating base material 22a.

  The protective layer 26 is patterned so that two portions of the conductor patterns 23 and 23 are exposed in the vicinity of the window hole 24 of the wiring substrate 22 and one portion of the conductor patterns 23 and 23 is exposed in the peripheral portion of the wiring substrate 22. In each of the conductor patterns 23 and 23, two rectangular portions exposed in the vicinity of the window hole 24 of the wiring board 22 constitute a terminal portion 23a to which a bonding wire is connected. The circular portion exposed in FIG. 3 constitutes the external connection electrode portion 23b. The conductor patterns 23 and 23 of the wiring board 22 are constituted by a laminated film of a Cu film, a Ni film, and an Au film. Further, of the two external connection electrode portions 23b, the external connection electrode portion 23b (the external connection electrode on the right side in FIG. 2) to which the anode electrode of the LED chip 10 on the high potential side of the series circuit described above is electrically connected. In the electrode portion 23b), a sign “+” is formed, and the external connection electrode portion 23b (on the left side in FIG. 2) to which the cathode electrode of the LED chip 10 on the low potential side of the series circuit is electrically connected is formed. Since the sign “-” is formed on the external connection electrode portion 23b), the polarities of both the external connection electrode portions 23b and 23b in the light emitting device 1 can be visually recognized, and erroneous connection can be prevented. it can.

  By the way, the above-mentioned plurality of LED chips 10 are arranged via the above-mentioned submount member 30 that relieves stress acting on each LED chip 10 due to the difference in linear expansion coefficient between each LED chip 10 and the heat transfer plate 21. And mounted on the heat transfer plate 21. Here, the submount member 30 is formed in a rectangular shape having a larger planar size than the combined planar size of the plurality of LED chips 10 as a whole.

  The submount member 30 has not only a function of relieving the stress but also a heat conduction function of transferring heat generated in each LED chip 10 to a range wider than the chip size of each LED chip 10 in the heat transfer plate 21. is doing. In short, in the light emitting device 1 of the present embodiment, each LED chip 10 is mounted on the heat transfer plate 21 via the submount member 30, so that heat generated in each LED chip 10 is transferred to the submount member 30 and the heat transfer. The heat can be efficiently radiated through the plate 21, and the stress acting on each LED chip 10 due to the difference in linear expansion coefficient between each LED chip 10 and the heat transfer plate 21 can be relaxed.

  In the present embodiment, AlN having a relatively high thermal conductivity and insulating property is employed as the material of the submount member 30. The submount member 30 is formed of an insulating material, and a plurality of LED chips 10 are formed. The mounted member to be mounted is configured. Here, the submount member 30 includes a rectangular plate-shaped base portion 30a and a protruding portion on one surface of the base portion 30a, and each LED chip 10 is individually soldered (for example, lead-free solder such as AuSn or SnAgCu). And a plurality of island-shaped chip mounting portions 30b in which the conductor patterns 31 to be joined are formed. Here, since the base part 30a and each chip mounting part 30b are continuously formed integrally in the submount member 30, the relative positional accuracy of each chip mounting part 30a can be improved.

  In the light emitting device 1 of the present embodiment, the thickness dimension of the submount member 30 is set so that the surface of the submount member 30 is farther from the heat transfer plate 21 than the surface of the protective layer 26 of the wiring board 22. In addition, light emitted from the LED chip 10 to the side can be prevented from being absorbed by the wiring board 22 through the inner peripheral surface of the window hole 24 of the wiring board 22. The conductor pattern 31 may be formed of a laminated film of, for example, a Ti layer as an adhesion layer, a Pt layer as a diffusion prevention layer, and an Au layer. Further, the material of the adhesion layer described above is not limited to Ti, but may be, for example, Ta, Ni, W, Zr, Hf, Cr, and the like. The material of the diffusion prevention layer is not limited to Pt. Pd, Rh, Ru, W, etc. may be used.

  As the sealing resin that is the material of the sealing portion 50 described above, a silicone resin is used. However, the sealing resin is not limited to the silicone resin, and for example, an acrylic resin may be used.

  The optical member 60 is a molded product of a translucent material (for example, silicone resin, glass, etc.) and is formed in a dome shape. Here, in this embodiment, since the optical member 60 is formed of a silicone resin molded product, the difference in refractive index and the linear expansion coefficient between the optical member 60 and the sealing portion 50 can be reduced. In addition, when the material of the sealing part 50 is an acrylic resin, it is preferable to form the optical member 60 also with an acrylic resin.

  By the way, the optical member 60 has a light exit surface 60b formed in a convex curved surface shape that does not totally reflect the light incident from the light incident surface 60a at the boundary between the light exit surface 60b and the air layer 80 described above. Therefore, the light emitted from each LED chip 10 and incident on the light incident surface 60a of the optical member 60 can easily reach the color conversion member 70 without being totally reflected at the boundary between the light emitting surface 60b and the air layer 80. , The total luminous flux can be increased. The light emitted from the side surface of each LED chip 10 propagates through the sealing portion 50, the optical member 60, and the air layer 80 to reach the color conversion member 70 and excites the phosphor of the color conversion member 70, or the phosphor. Or the color conversion member 70 is transmitted without colliding. Further, the optical member 60 is formed so that the thickness is uniform along the normal direction regardless of the position.

  The color conversion member 70 is a mixture of a translucent material such as a silicone resin and a particulate yellow phosphor that emits broad yellow light when excited by the blue light emitted from each LED chip 10. (That is, the color conversion member 70 contains a phosphor). Therefore, in the light emitting device 1 of the present embodiment, the blue light emitted from the LED chip 10 and the light emitted from the yellow phosphor are emitted through the outer surface 70b of the color conversion member 70, and white light is obtained. Can do. The translucent material used as the material of the color conversion member 70 is not limited to a silicone resin, but an organic / inorganic hybrid in which, for example, an acrylic resin, glass, an organic component and an inorganic component are mixed and combined at the nm level or the molecular level. Materials etc. may be adopted. Further, the phosphor mixed with the translucent material used as the material of the color conversion member 70 is not limited to the yellow phosphor. For example, white light can be obtained by mixing a red phosphor and a green phosphor.

  Here, the color conversion member 70 has an inner surface 70 a formed along the light emitting surface 60 b of the optical member 60. Therefore, the distance between the light emitting surface 60b and the inner surface 70a of the color conversion member 70 in the normal direction is a substantially constant value regardless of the position of the light emitting surface 60b of the optical member 60. In addition, the color conversion member 70 is shape | molded so that the thickness along a normal line direction may become uniform irrespective of a position. In addition, the color conversion member 70 may be fixed to the mounting substrate 20 with an end edge (periphery of the opening) on the mounting substrate 20 side using, for example, an adhesive (for example, silicone resin, epoxy resin).

  By the way, although the above-mentioned lighting fixture which used the light-emitting device 1 of this embodiment as a light source is not shown in figure, the wiring pattern which prescribes | regulates the connection relation of each light-emitting device 1 is formed in the one surface side of an insulating base material. Circuit board. In the present embodiment, the plurality of light emitting devices 1 are connected in series. However, the connection relationship between the plurality of light emitting devices 1 is not particularly limited. For example, the light emitting devices 1 may be connected in parallel or connected in series. And parallel connection may be combined. In addition, the circuit board is disposed, for example, in a shallow bottomed cylindrical instrument body 100 so as to be separated from the bottom wall of the instrument body 100, and each light-emitting device 1 is provided at a portion corresponding to each light-emitting device 1. An aperture window through which a part of 1 is passed is formed. Moreover, the shape of the instrument main body 100 is not specifically limited, For example, flat form may be sufficient.

  Moreover, in the light-emitting device 1 in this embodiment, since the planar size of the sheet-like joining member 90 is set larger than the planar size of the heat transfer plate 21, the joining member 90 and the heat transfer plate 21 are the same. Compared with the case where it is formed in a planar size, the creeping distance between the heat transfer plate 21 and the appliance body 100 that is a metal member can be increased, and lightning surge resistance when used as a light source for a lighting fixture can be increased. (However, the creepage distance between the light emitting device and the metal member, which is generally required for indoor lighting fixtures and outdoor lighting fixtures, is different, and outdoor lighting fixtures have longer creepage distances. As required). Here, the thickness of the sheet-like joining member 90 needs to be designed in accordance with the lightning surge resistance required withstand voltage, but it is desirable to set it thinner from the viewpoint of reducing thermal resistance. Therefore, regarding the joining member 90, after setting the thickness, the planar size may be set so that the creepage distance requirement can be satisfied.

  By the way, in the manufacturing method of the light-emitting device 1 described above, for example, each LED chip 10 is mounted on the submount member 30 and then a series circuit of the LED chips 10 is formed by performing a wire bonding process, and then a wiring board. Liquid sealing resin (for example, silicone resin) that becomes a part of the sealing portion 50 in the gap between the submount member 30 and the wiring board 22 from the resin injection hole 28 formed continuously to the window hole 24 of 22. After the liquid is injected, the liquid is cured, and after that, a liquid sealing resin (for example, silicone resin) that becomes the remaining portion of the sealing portion 50 is injected into the inside of the dome-shaped optical member 60, and then the optical member 60. Is placed at a predetermined position on the mounting substrate 20 and the sealing resin 50 is cured to form the sealing portion 50 and at the same time, the optical member 60 is fixed to the mounting substrate 20. A manufacturing method in which the color conversion member 70 is fixed to the mounting substrate 20 is conceivable. However, even in such a manufacturing method, bubbles (voids) may be generated in the sealing portion 50 during the manufacturing process. It is necessary to inject a large amount of liquid sealing resin into 60.

  Therefore, in the light emitting device 1 of the present embodiment, as described above, when the optical member 60 is fixed to the mounting substrate 20 outside the optical member 60 on the one surface of the mounting substrate 20, the space (with the optical member 60 and the optical member 60). An annular (in the present embodiment, annular) dam portion 27 is provided to dam up the sealing resin overflowing from the space surrounded by the mounting substrate 20. Here, the dam portion 27 is formed of a white resist. In addition, the dam portion 27 extends inward from the inner peripheral surface of the dam portion 27 to center the center of the dam portion 27 and the central axis of the optical member 60 (four in this embodiment). The claw portions 27b are spaced apart in the circumferential direction and provided at equal intervals, and also serve as a positioning portion for the color conversion member 70. Here, the number of the claw portions 27b for centering is not limited to four, but it is desirable to provide at least three, and the sealing resin that can be stored between the dam portion 27 and the optical member 60 In order to increase the permissible amount, it is desirable that the width dimension of the centering claw portion 27b is small.

  Therefore, in the light emitting device 1 according to the present embodiment, it is difficult to generate voids in the sealing portion 50 during the manufacturing process, and the light emitting device 1 having high reliability and high light output can be provided. In FIG. 1A, the resin portion 50b interposed between the optical member 60 and the dam portion 27 is composed of the optical member 60, the dam portion 27, and the protective layer 26 on the one surface side of the mounting substrate 20. It is formed by curing the sealing resin accumulated in the enclosed space.

  Further, the color conversion member 70 has a notch 71 that engages with the weir 27 on the edge of the mounting substrate 20 side over the entire circumference. Therefore, in the light emitting device 1 according to the present embodiment, the positioning accuracy of the color conversion member 70 with respect to the mounting substrate 20 can be increased, and the interval between the color conversion member 70 and the optical member 60 can be shortened. The notch 71 is open on the edge side and the inner surface 70a side of the color conversion member 70.

  Since the light emitting device 1 of the present embodiment described above has the conductor patterns 23 and 23 for feeding power to the series circuit of the plurality of LED chips 10 on the one surface side of the mounting substrate 20, the mounting substrate 20 is mounted. The board 20 can be thermally coupled to the fixture body 100 of the lighting fixture without being mounted on the circuit board, the thermal resistance from each LED chip 10 to the fixture body 100 can be reduced, and the heat dissipation is improved. Since the temperature rise of the junction temperature of 10 can be suppressed, the input power can be increased and the optical output can be increased. Further, in the light emitting device 1 described above, since the weir portion 27 is provided on the one surface of the mounting substrate 20, generation of voids in the sealing portion 50 during manufacturing can be suppressed.

  By the way, as described above, the submount member 30 has a plurality of island-shaped chip mounting portions 30b in which the conductor patterns 31 to which the LED chips 10 are individually joined by solder are formed. The planar size of the rectangular tip surface 30b is set smaller than the planar size of the LED chip 10. Moreover, it is preferable that the shape in plan view of the chip mounting portion 30b is the same shape (similar shape) as the shape of the LED chip 10. This is because the alignment accuracy in the rotational direction is improved by using a similar shape. The conductor pattern 31 may be formed by, for example, a sputtering method, a vapor deposition method, a plating method, or the like.

  Thus, in the light emitting device 1 of the present embodiment, the submount member 30 has a plurality of island-shaped chip mounting portions 30b in which the conductor patterns 31 to which the LED chips 10 are individually joined by solder are formed, Since the planar size of the tip surface of the chip mounting part 30b is set smaller than the planar size of the LED chip 10, when the LED chip 10 is joined to the conductive pattern 31 of each chip mounting part 30b, By applying a self-alignment process in which the LED chip 10 is positioned using the surface tension of the solder heated and melted after applying an appropriate amount of solder 15a (see FIG. 4), the positioning accuracy of the LED chip 10 is improved. And a joint 15 made of solder joining the LED chip 10 and the conductor pattern 31 (FIG. 1 ( )) Is tapered from the LED chip 10 toward the conductor pattern 31, so that the solder can be prevented from protruding from within the projection area in the thickness direction of the LED chip 10. This makes it possible to prevent a short circuit between the LED chips 10 due to soldering, while narrowing the distance between the two. Further, there is an advantage that it is possible to prevent the solder protruding from between the LED chip 10 and the conductor pattern 31 from becoming a solder ball and short-circuiting the junction of the LED chip 10.

  In the above-described embodiment, a blue LED chip whose emission color is blue is adopted as the LED chip 10, but the light emitted from the LED chip 10 is not limited to blue light, for example, red light or green light. Purple light, ultraviolet light, etc. may be used. In addition, the LED chip 10 may be one in which a color conversion layer made of the same material as that of the color conversion member 70 is laminated. In this case, the color conversion member 70 becomes unnecessary. In the above-described embodiment, the light emission colors of all the LED chips 10 mounted on the submount member 30 as the mounted member are the same, but a plurality of types of LED chips 10 having different light emission colors are mounted. For example, the LED chips 10 whose emission colors are red, green, and blue may be mounted. In this case, the color conversion member 70 is not necessary. Further, the mounted member is not limited to the submount member, and may be, for example, a circuit board or a ceramic package.

An embodiment is shown, (a) is a schematic sectional drawing, (b) is a schematic sectional drawing, and (c) is an important section schematic sectional drawing. It is a general | schematic disassembled perspective view which showed the same and partially fractured | ruptured. It is a schematic perspective view of the submount member in the same as the above. It is explanatory drawing of the manufacturing method of a light-emitting device same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light-emitting device 10 LED chip 15 Joint part 30 Submount member (mounted member)
30a Base part 30b Chip mounting part 31 Conductor pattern

Claims (1)

  A plurality of LED chips and a single mounted member formed of an insulating material and mounted with the plurality of LED chips, and the mounted member is a conductor pattern in which each LED chip is joined by solder separately. A light-emitting device comprising a plurality of island-shaped chip mounting portions each having a shape in which a planar size of a tip surface of the chip mounting portion is set smaller than a planar size of an LED chip.

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