JP2020053642A - Manufacturing method of light-emitting device - Google Patents

Abstract

To provide a manufacturing method of a light-emitting device capable of manufacturing a light-emitting device having a small size and a reduced light-emitting area in a relatively simple process.SOLUTION: A manufacturing method of a light-emitting device 1 according to an embodiment of the present invention includes a step of installing one plate-shaped wavelength conversion member 30 on a plurality of light emitting elements 20, a step of covering the side surfaces of the plurality of light emitting elements 20 and the outer edge of the upper surface and the side surface of the wavelength conversion member 30 with a resin 51 having fluidity at once by screen printing, and a step of curing the resin 51 to form a light reflecting member 50, and the resin 51 is pressure-discharged onto a mask 70 having openings 71 that are distributed in a ring shape, and the resin 51 that has passed through the openings 71 covers the side surfaces of the light emitting element 20 and the outer edge of the upper surface and the side surface of the wavelength conversion member.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing a light emitting device.

  2. Description of the Related Art As a conventional light emitting device, there is known a light emitting device in which a side surface of a wavelength conversion member including a phosphor disposed thereon is covered with a light reflecting member (for example, see Patent Documents 1 and 2).

  In the light-emitting device described in Patent Literature 1, a wavelength conversion member having a smaller area than the light-emitting element is used in order to reduce the light-emitting area, and light is emitted from a portion of the light-emitting element that is not covered by the wavelength conversion member. The reflected light is guided to the wavelength conversion member by the light reflection member.

  In the light emitting device described in Patent Literature 2, the outer edge of the upper surface of the wavelength conversion member is covered with the light reflecting member. For this reason, it is possible to prevent light emitted from the light emitting element from being directly extracted from the outer edge of the wavelength conversion member, and to suppress color unevenness of light emission of the light emitting device.

Japanese Patent No. 6164038 Japanese Patent No. 5915483

  In the light emitting device described in Patent Literature 1, the light emitting element is surrounded by an annular dam, and the wavelength conversion member is formed by being injected in a liquid state inside the dam and hardening. However, since the area occupied by the dam is larger than the area of the light emitting element, it is difficult to reduce the size of the light emitting device described in Patent Document 1.

  Further, in the light emitting device described in Patent Document 2, the light reflecting member includes a light emitting element and a first layer that covers the side of the wavelength conversion member thereon, and an outer edge of an upper surface of the wavelength conversion member provided thereon. It is composed of a second layer covering the portion, and is formed by screen printing or the like. However, the manufacturing process of the light reflecting member composed of two layers is complicated, and the resin cannot be handled with a high viscosity by ordinary screen printing, so that it is difficult to control the shape. It is difficult to form.

  An object of the present invention is to provide a method for manufacturing a light-emitting device that can manufacture a light-emitting device having a small size and a reduced light-emitting area by relatively simple steps.

  One embodiment of the present invention provides a method for manufacturing a light-emitting device according to the following [1] to [5] to achieve the above object.

[1] A step of mounting a plurality of light emitting elements on a substrate, and a step of installing one plate-shaped wavelength conversion member on the plurality of light emitting elements so as to cover the plurality of light emitting elements when viewed from above. Covering the outer edges and side surfaces of the side surfaces of the plurality of light emitting elements and the upper surface of the wavelength conversion member with a resin having fluidity at a time by screen printing, and curing the resin to form a light reflecting member And the step of covering the outer edge and the side surface of the side surface of the light emitting element and the upper surface of the wavelength conversion member at once with a resin having fluidity, wherein the mask having annularly distributed openings, The resin is pressurized and discharged onto the mask in a state where the opening is located right above an outer edge of the upper surface of the wavelength conversion member and a peripheral region having a predetermined width around the wavelength conversion member. And said Covering the side surface and the outer edge and side of the upper surface of the wavelength conversion member of the light emitting element in the resin having passed through the mouth, the method of manufacturing the light emitting device.
[2] The method for manufacturing a light emitting device according to [1], wherein the viscosity of the resin is 150 Pa · s or more and 500 Pa · s or less.
[3] The method for manufacturing a light emitting device according to [1] or [2], wherein the predetermined width in the longitudinal direction of the wavelength conversion member in a top view is 0.2 mm or more and 0.4 mm or less.
[4] Any of the above [1] to [3], wherein the predetermined width in the longitudinal direction of the wavelength conversion member in a top view is smaller than the predetermined width in the short direction of the wavelength conversion member in a top view. 9. The method for manufacturing a light emitting device according to claim 1.
[5] In the step of simultaneously covering the side surface of the light emitting element and the outer edge and the side surface of the upper surface of the wavelength conversion member with a resin having fluidity, the printing direction of the screen printing may be changed in a top view of the wavelength conversion member. The method for manufacturing a light-emitting device according to any one of the above [1] to [4], wherein the light-emitting device is aligned in a lateral direction.

  According to the present invention, it is possible to provide a method for manufacturing a light-emitting device that can manufacture a light-emitting device having a small size and a reduced light-emitting area in a relatively simple process.

FIG. 1A is a top view of the light emitting device according to the first embodiment. FIG. 1B is a top view of the light emitting device in which the light reflecting member is not shown. FIGS. 2A and 2B are vertical cross-sectional views of the light emitting device taken along a line AA and a line BB in FIG. 1A, respectively. FIGS. 3A to 3D are vertical cross-sectional views illustrating manufacturing steps of the light emitting device according to the first embodiment. FIGS. 4A to 4D are explanatory views of a screen printing mask used in the manufacturing process of the light emitting device according to the first embodiment. FIG. 5 is a vertical sectional view showing details of the screen printing process. FIG. 6 is a top view of the light emitting device according to the second embodiment. FIG. 7 is a vertical cross-sectional view of the light emitting device taken along a line indicated by line DD in FIG. FIG. 8 is a top view of the light emitting device according to the third embodiment.

[First Embodiment]
(Configuration of light emitting device)
FIG. 1A is a top view of the light emitting device 1 according to the first embodiment. FIG. 1B is a top view of the light emitting device 1 in which the light reflecting member 50 is not shown. In FIG. 1A, the outlines of the wavelength conversion member 30 and the wiring 12 located below the light reflection member 50 are indicated by dotted lines. In FIG. 1B, the outline of the light reflecting member 50 and the outline of the light emitting element 20 located below the wavelength conversion member 30 are indicated by dotted lines.

  FIGS. 2A and 2B are vertical cross-sectional views of the light-emitting device 1 taken along a position indicated by a line AA and a position indicated by a line BB in FIG. 1A, respectively. .

  The light emitting device 1 includes a wiring board 10 having wirings 12 provided on a surface of a substrate 11, a plurality of light emitting elements 20 face-down mounted on the wiring board 10, and a single light emitting element mounted on the plurality of light emitting elements 20. And a light reflecting member 50 that covers the wavelength conversion member 30 and the light emitting element 20.

  The light emitting element 20 is, for example, a flip chip type LED chip having an element substrate 21, a light emitting function layer 22 including a light emitting layer and a cladding layer sandwiching the light emitting layer, and a device electrode 23 connected to the light emitting function layer 22. Further, the light emitting element 20 may be a face-up type element. The planar shape of the light emitting element 20 is, for example, a square or a rectangle having one side length of 0.5 to 8.0 mm, and the thickness is, for example, 0.05 to 0.3 mm.

  The number of light emitting elements 20 included in the light emitting device 1 is not particularly limited, but is, for example, 2 to 100 elements. In the examples shown in FIGS. 1A, 1B and 2, a plurality of light emitting elements 20 arranged in one direction are connected in series.

  The element electrode 23 of the light emitting element 20 is connected to the wiring 12 of the wiring board 10. An underfill may be filled between the wiring substrate 10 and the light emitting element 20.

The substrate 11 is, for example, a ceramic substrate such as an Al ₂ O ₃ substrate or an AlN substrate, a metal substrate such as an Al substrate or a Cu substrate whose surface is covered with an insulating film, or a glass epoxy substrate. Of a conductive material. Further, the substrate 11 may be a resin substrate or a paper substrate. The planar shape of the substrate 11 is, for example, a square or a rectangle having a side length of 2 to 50 mm, and the thickness is, for example, 0.2 to 2.0 mm.

  The wavelength conversion member 30 is a member that absorbs light emitted from the light emitting element 20 and emits light of different wavelengths. For example, a sintered body of a phosphor, a sintered body of a fluorescent substance and an inorganic substance, and a phosphor particle are used. Consists of dispersed glass. The wavelength conversion member 30 is a plate-shaped member and has a thickness of, for example, 0.05 to 0.3 mm.

  The type and fluorescent color of the phosphor contained in the wavelength conversion member 30 are not particularly limited. The light emitting element 20 functions as an excitation light source for the phosphor contained in the wavelength conversion member 30, and a mixed color of the emission color of the light emission element 20 and the emission color of the wavelength conversion member 30 becomes the emission color of the light emitting device 1. For example, when the emission color of the light emitting element 20 is blue and the emission color of the wavelength conversion member 30 is yellow, the emission color of the light emitting device 1 is white.

  The light emitting device 1 includes a plurality of light emitting elements 20, and one wavelength conversion member 30 covers upper surfaces of the plurality of light emitting elements 20. In addition, the area of the wavelength conversion member 30 is larger than the area of the plurality of light emitting elements 20, and the plurality of light emitting elements 20 are covered with the wavelength conversion member 30 in a top view as shown in FIG.

  The adhesive 40 is an adhesive for bonding the light emitting element 20 and the wavelength conversion member 30. The adhesive 40 is made of, for example, a translucent thermosetting resin such as a silicone resin or an epoxy resin.

  After the light emitting element 20 and the wavelength conversion member 30 are bonded, the adhesive 40 remains on the side of the light emitting element 20 so as to cover the side surface of the light emitting element 20 and the lower surface of the wavelength conversion member 30, and the surface thereof is An inclined surface 41 that extends from the side surface of the wavelength conversion member 20 to the lower surface of the wavelength conversion member 30 is formed. The inclined surface 41 functions as a light reflecting surface that reflects light emitted laterally from the light emitting element 20.

  The light reflecting member 50 has a property of reflecting light emitted from the light emitting element 20, and is, for example, a light of silicone-based resin or epoxy-based resin containing a reflective filler such as titanium oxide, silicon oxide, boron nitride, and aluminum nitride. It is made of a transparent resin. It is preferable that the reflectance of light emitted from the light emitting element 20 of the light reflecting member 50 be 80% or more.

  The light reflecting member 50 includes a side surface of the light emitting element 20, an outer edge portion and a side surface of an upper surface of the wavelength conversion member 30, and an adhesive so that light emitted from the light emitting element 20 does not leak without passing through the wavelength conversion member 30. It covers 40.

The x direction and the y direction shown in FIGS. 1A and 1B respectively indicate the longitudinal direction and the lateral direction of the wavelength conversion member 30 as viewed from above. Figure 1 (a), (b) , FIG. 2 (a), _{W x} which (b), the the width of the light reflecting member 50 from the side of the wavelength conversion member 30 in the x-direction. Figure 1 (a), (b) , FIG. 2 (a), _{W y} of (b), the the width of the light reflecting member 50 from the side of the wavelength conversion member 30 in the y-direction.

Since the light reflecting member 50 can be formed by using a resin having a high viscosity as described later, compared with a case where a conventional method using a resin having a relatively low viscosity such as screen printing or potting using a squeegee is used. Therefore, it can be formed with a small width. Thus, for example, it may be less difficult 0.4mm in light-emitting device using a conventional dam width W _x and the width W _y. However, to prevent transmission of light, it is preferable that the width _{W x} and the width _{W y} or more 0.2 mm.

  By reducing the width of the light reflecting member 50, the light emitting device 1 can be downsized. Also, if the width of the light reflecting member 50 is small, the amount of expansion when the temperature rises is small, so that it is difficult to break. For this reason, it is possible to prevent the emission color of the light emitting device 1 from shifting due to leakage of light emitted from the light emitting element 20.

Further, the smaller the width _Wx and the width _Wy , the smaller the light emitting device 1 can be. However, it is more difficult to form the light reflecting member 50 by screen printing. Therefore, by reducing the width W _x which is required to be particularly small in order to reduce the size of the light emitting device 1 is made larger than the width W _x width W _y in order to facilitate the formation of the light reflecting member 50 Is preferred.

For these reasons, as an example, more than 0.2mm of width _{W x,} and 0.4mm or less, it is preferably larger than the width _{W x} width _{W y.}

  Since the light reflecting member 50 covers the outer edge of the upper surface of the wavelength conversion member 30, the light emitting area of the light emitting device 1 can be reduced. Then, by adjusting the area where the light reflecting member 50 covers the upper surface of the wavelength conversion member 30, the light emitting area of the light emitting device 1 can be adjusted. Unlike the case where the light emitting area is reduced by downsizing the wavelength converting member 30, it is not necessary to process the wavelength converting member 30 according to the light emitting area. Further, unlike the case where the light emitting area is reduced by reducing the chip size of the light emitting element 20, there is no reduction in brightness due to the reduction in chip size.

  Further, since the light reflecting member 50 can be formed by screen printing using a resin having a high viscosity, the lattice pattern of the opening of the mask used for screen printing is transferred to the upper surface. That is, the upper surface of the light reflecting member 50 has irregularities formed of concave portions continuous in a lattice shape and concave portions located in each of the regions partitioned by the concave portions.

  In addition, since the surface area is increased by having the unevenness, the heat radiation property is improved. Therefore, by including a heat radiation filler such as AlN (whisker), BN, or graphene with high heat radiation in the light reflection member 50, the heat radiation of the light reflection member 50 is improved by a synergistic effect with an increase in surface area due to unevenness on the upper surface. Greatly improved.

  In addition, since the light reflecting member 50 is formed all at once by screen printing, the light reflecting member 50 has a single-layer structure and does not have a boundary surface that causes peeling.

  The light emitting device 1 may include a protection element such as a Zener diode.

(Method of manufacturing light emitting device)
Hereinafter, an example of a method for manufacturing the light emitting device 1 according to the first embodiment will be described.

  FIGS. 3A to 3D are vertical cross-sectional views illustrating manufacturing steps of the light emitting device 1 according to the first embodiment. FIGS. 4A to 4D are explanatory diagrams of a screen printing mask 70 used in the manufacturing process of the light emitting device 1 according to the first embodiment. FIG. 4A is a top view of the mask 70, and FIG. 4B is a vertical cross-sectional view of the mask 70 cut at a position indicated by a line CC in FIG. (C) is a bottom view of the mask 70.

  First, as shown in FIG. 3A, a plurality of light emitting elements 20 are mounted on the wiring board 10. The element electrode 23 of the light emitting element 20 and the wiring 12 of the wiring board 10 are bonded by ultrasonic bonding, metal paste bonding, eutectic solder bonding, or the like.

  Next, as shown in FIG. 3B, the wavelength conversion member 30 is provided on the light emitting element 20. At this time, one plate-shaped wavelength conversion member 30 is provided on the plurality of light emitting elements 20 so as to cover the plurality of light emitting elements 20 when viewed from above.

  The wavelength conversion member 30 is adhered to the light emitting element 20 by an adhesive 40. After the light emitting element 20 and the wavelength conversion member 30 are bonded, the adhesive 40 remains on the side of the light emitting element 20 so as to cover the side surface of the light emitting element 20 and the lower surface of the wavelength conversion member 30 to form the inclined surface 41. .

  Next, as shown in FIG. 3C, a mask 70 for screen printing is set on the wiring board 10.

  As shown in FIG. 4A, the mask 70 has a plurality of openings 71 that are annularly distributed. The opening 71 is an area through which the resin passes during screen printing. The mask 70 is, for example, a metal mask having an aggregate of fine holes as the opening 71 or a screen mask having a mesh as the opening 71. The plurality of openings 71 of the mask 70 have a grid pattern such as a square grid in order to hold a region where the openings 71 are distributed and a region surrounded by the regions.

  The annular distribution area of the opening 71 of the mask 70 corresponds to the formation area of the light reflecting member 50. An unopened area 73 surrounded by the annularly distributed openings 71 corresponds to an area of the upper surface of the wavelength conversion member 30 that is not covered by the light reflecting member 50.

  The mask 70 has, on the back surface of the region 73, a contact portion 72 that contacts the upper surface of the wavelength conversion member 30 during screen printing. As shown in FIG. 4B, the contact portion 72 is thicker than the opening 71 and protrudes from the back side of the mask 70. The contact portion 72 forms a portion that covers the outer edge of the upper surface of the wavelength conversion member 30 of the light reflecting member 50 due to the thickness difference (step) of the opening 71.

  The contact portion 72 is preferably provided only on the outer edge of the back surface of the region 73 as shown in FIGS. This is to prevent the resin from entering the vicinity of the center of the wavelength conversion member 30 through the interface between the wavelength conversion member 30 and the contact portion 72 during screen printing.

  In the step illustrated in FIG. 3C, a region where the light reflecting member 50 is formed, that is, an outer edge of the upper surface of the wavelength conversion member 30 and a peripheral region having a predetermined width around the wavelength conversion member 30, The mask 70 is set so that the openings 71 distributed in a ring shape are located.

The above-mentioned predetermined width of the peripheral region of the wavelength conversion member 30 corresponds to the width of the light reflecting member 50 from the side surface of the wavelength conversion member 30. Therefore, in order to be larger than the width W _y the width W _x of the light reflecting member 50, a predetermined width in the x direction (longitudinal direction in the top view of the wavelength conversion member 30) in the y-direction (the wavelength converting member 30 (Shorter direction in top view). Further, for example, the width _{W x} of 0.2mm or more light reflecting member 50, in order to 0.4mm or less, more 0.2mm a predetermined width in the x direction, to 0.4mm or less.

  Next, as shown in FIG. 3D, the side surface of the light emitting element 20 and the outer edge and side surface of the upper surface of the wavelength conversion member 30 are covered with the resin 51 at a time by screen printing.

  FIG. 5 is a vertical sectional view showing details of the screen printing process. The resin 51 having fluidity, which is a material of the light reflecting member 50, is discharged under pressure onto the mask 70 by using a cartridge 60 of a screen printing machine. The resin 51 that has been pressed and discharged onto the mask 70 and has passed through the opening 71 covers the side surface of the light emitting element 20 and the outer edge and side surface of the upper surface of the wavelength conversion member 30.

The viscosity of the resin 51 is preferably 150 Pa · s or more and 500 Pa · s or less. If the viscosity of the resin 51 is less than 150 Pa · s, the shape tends to collapse until the resin 51 is cured, a small width to form a (e.g., width _{W x} of the following 0.4 mm) light reflecting member 50 It becomes difficult. On the other hand, if the viscosity of the resin 51 exceeds 500 Pa · s, it becomes difficult to discharge or print the resin 51 from the cartridge 60.

  When handling the resin 51 having a high viscosity of 150 Pa · s or more, the conventional method using a squeegee does not have enough downward pressure applied to the resin 51, so that it is difficult to perform printing.

In order to accurately inject the resin 51 into the space below the opening 71 of the mask 70, the printing direction, that is, the moving direction of the cartridge 60, should be in the y direction (the short direction in the top view of the wavelength conversion member 30). preferable. In particular, the width W _y of the light reflecting member 50 is larger than the width W _x, the printing direction by the y-direction, can be injected accurately resin 51 by the space under the opening 71 of the mask 70.

  The opening 61 for discharging the resin 51 of the cartridge 60 is rectangular, and printing is performed with the short side direction of the opening 61 corresponding to the printing direction. If the width of the opening 61 in the longitudinal direction is larger than the width of the printing area (for example, if the printing direction is the y direction, if the width in the longitudinal direction is larger than the width of the light reflecting member 50 in the x direction), The light reflecting member 50 can be formed by one printing.

  The printing conditions include, for example, when the width of the opening 61 in the short direction is 3 mm, the viscosity of the resin 51 is 250 Pa · s, the filling pressure of the resin into the cartridge 60 is 0.5 N, and the printing speed (movement of the cartridge 60). Speed) is set to 21 mm / s. When the width of the opening 61 in the short direction is 10 mm, the viscosity of the resin 51 is set to 250 Pa · s, the filling pressure of the resin 51 into the cartridge 60 is set to 0.5 N, and the printing speed is set to 45 mm / s.

  After that, the resin 51 covering the side surface of the light emitting element 20 and the outer edge and side surface of the upper surface of the wavelength conversion member 30 is cured by a heat treatment to form the light reflecting member 50.

[Second embodiment]
The second embodiment differs from the first embodiment in the shape of the light reflecting member 50. The description of the same points as in the first embodiment will be omitted or simplified.

(Configuration of light emitting device)
FIG. 6 is a top view of the light emitting device 2 according to the second embodiment. FIG. 7 is a vertical cross-sectional view of the light emitting device 2 taken along a position indicated by a line segment DD in FIG.

  In the light emitting device 2, one wavelength conversion member 30 is provided for each of the light emitting elements 20. According to this structure, the uniformity of the thickness of the adhesive material 40 is improved, and a decrease in heat dissipation can be suppressed.

  Further, in the light emitting device 2, the wavelength conversion member 30 is separated, and the space between the separated wavelength conversion members 30 is filled with the light reflection member 50. Therefore, the wavelength conversion member 30 installed on a specific light emitting element 20 does not emit light (pseudo lighting) by light emitted from the adjacent light emitting element 20. In addition, it is possible to suppress a decrease in light extraction efficiency due to internal light guide of the wavelength conversion member 30. The light emitting device 2 can also be manufactured by the same method as the light emitting device 1 according to the first embodiment.

[Third Embodiment]
The third embodiment is different from the first and second embodiments in the number and arrangement of the light emitting elements 20 and the shape of the light reflecting member 50. The description of the same points as those in the first and second embodiments will be omitted or simplified.

(Configuration of light emitting device)
FIG. 8 is a top view of the light emitting device 3 according to the third embodiment.

  In the light emitting device 3, the plurality of light emitting elements 20 are arranged not in one row but in a plurality of rows, that is, in a matrix. Thus, the effect of the present invention can be obtained even when many light emitting elements 20 are arranged in a plane to extract more light. The light emitting device 3 can also be manufactured by the same method as the light emitting device 1 according to the first embodiment.

(Effects of Embodiment)
According to the first to third embodiments, a light-emitting device having a small size and a small light-emitting area can be obtained by a relatively simple process.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the invention. Further, the components of the above embodiments can be arbitrarily combined without departing from the gist of the invention.

  The above embodiments do not limit the invention according to the claims. Also, it should be noted that not all combinations of the features described in the embodiments are necessarily indispensable for means for solving the problems of the invention.

1, 2, 3 Light-emitting device 10 Wiring board 20 Light-emitting element 30 Wavelength conversion member 40 Adhesive material 41 Inclined surface 50 Light reflection member 51 Resin 60 Cartridge 61 Opening 70 Mask 71 Opening 72 Contact part

Claims (5)

Mounting a plurality of light emitting elements on a substrate,
Installing a single plate-shaped wavelength conversion member on the plurality of light emitting elements so as to cover the plurality of light emitting elements in a top view;
By screen printing, a step of covering the outer edges and side surfaces of the side surfaces of the plurality of light emitting elements and the upper surface of the wavelength conversion member at once with a resin having fluidity,
Curing the resin to form a light reflecting member,
Including
In the step of simultaneously covering the side surface of the light emitting element and the outer edge and the side surface of the upper surface of the wavelength conversion member with a resin having fluidity, a mask having an annularly distributed opening is formed on the outer edge of the upper surface of the wavelength conversion member. The resin is pressurized and discharged onto the mask in a state where the opening is located right above a peripheral region having a predetermined width around the portion and the wavelength conversion member, and passes through the opening. The resin covers the side surface of the light emitting element and the outer edge and side surface of the upper surface of the wavelength conversion member,
A method for manufacturing a light emitting device. The viscosity of the resin is 150 Pa · s or more and 500 Pa · s or less,
A method for manufacturing the light emitting device according to claim 1. The predetermined width in the longitudinal direction in the top view of the wavelength conversion member is 0.2 mm or more, 0.4 mm or less,
A method for manufacturing the light emitting device according to claim 1. The predetermined width in the longitudinal direction in the top view of the wavelength conversion member is smaller than the predetermined width in the short direction in the top view of the wavelength conversion member,
A method for manufacturing the light emitting device according to claim 1. In the step of simultaneously covering the outer edge and the side surface of the side surface of the light emitting element and the upper surface of the wavelength conversion member with a resin having fluidity, the printing direction of the screen printing is changed in a short direction in a top view of the wavelength conversion member. To match,
A method for manufacturing the light emitting device according to claim 1.

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