Method of manufacturing substrate and method of manufacturing light emitting device

A method of manufacturing a substrate for a light emitting device includes: forming wiring to form a plurality of first wiring parts and second wiring parts on/above an upper surface of a base member; forming projection parts including a first projection part on each of the first wiring parts and a second projection part on each of the second wiring parts by forming a first metal film on a region including at least parts of the first wiring parts and the second wiring parts and etching the first metal film using a resist for forming projection part; and forming an alignment mark by forming a second metal film on the substrate and etching the second metal film using a resist, wherein the resist for forming the projection part and the resist for forming alignment mark are exposed to light in an identical step of exposing to light.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2017-167379, filed on Aug. 31, 2017, the disclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates to a method of manufacturing a substrate for a light emitting device.

In recent years, light emitting devices including light emitting elements such as light emitting diodes are used in various applications, and their inexpensive availability is desired. In order to meet the needs, for example, Japanese Unexamined Patent Publication No. 2017-076719 discloses a method of manufacturing a light emitting device including a substrate, and a light emitting element and a resin sheet on the substrate. Specifically, what is disclosed is a method of manufacturing a light emitting device including: providing a resin sheet that comprises a lattice-patterned reflective material-containing portion and film-shaped phosphor-containing portions covering lattice openings of the reflective material-containing portion; placing the resin sheet on a substrate mounting a plurality of light-emitting elements such that each of the plurality of light-emitting elements is surrounded by the reflective material-containing portion and is covered on the top with the phosphor-containing portion; after placing the resin sheet on the substrate, softening the resin sheet by heating such that the phosphor-containing portions are adhered to the respective upper surfaces of the plurality of light-emitting elements and the reflective material-containing portion or the phosphor-containing portions is/are adhered to the side surfaces of the plurality of light-emitting elements; and curing the resin sheet and the substrate to obtain individual light emitting devices.

However, light emitting devices being more inexpensive and smaller in size and weight are now in increasing demand. There are some cases where light emitting devices are manufactured by: arranging a plurality of light emitting elements on a substrate; and after performing predetermined steps, cutting the substrate. In such cases, the light emitting elements must be precisely mounted at their respective predetermined positions, and the substrate must be precisely cut at each predetermined position. For example, with the light emitting device disclosed in the patent publication No. 2017-076719 in which the surroundings of the light emitting element and the fluorescent material containing part are covered with the reflective member containing part, the reflective member containing part may be minimized in thickness to achieve downsizing. On the other hand, with greater variance in the cutting positions relative to the mounting positions of the light emitting elements and the resin sheet, the reflective member containing part must be great in thickness taking into consideration of the amount of variance and, hence, downsizing is limited. Further, greater variance in the cutting positions relative to the mounting positions of the light emitting elements and the resin sheet result in poor yields. That is, cost efficiency cannot be achieved.

SUMMARY

Accordingly, an object of certain embodiment of the present disclosure is to provide a method of manufacturing a substrate with which the cutting positions are highly precisely adjustable relative to the mounting positions of reference light emitting elements.

Further, other object of certain embodiment of the present disclosure is to provide a method of manufacturing a light emitting device being cost-efficient and small in size.

A method of manufacturing a substrate according to certain embodiment of the present disclosure is a method of manufacturing a substrate for a light emitting device, the method including: forming wiring to form a plurality of first wiring parts and a plurality of second wiring parts on an upper surface of a base member; forming projection parts including a first projection part on each of the first wiring parts and a second projection part on each of the second wiring parts by forming a first metal film on a region including at least part of the first wiring parts and at least part of the second wiring parts and etching the first metal film using a resist having a predetermined shape for forming the projection parts; and forming at least one alignment mark by forming a second metal film on the substrate and etching the second metal film using a resist for forming the at least one alignment mark, wherein the resist for forming the projection parts and the resist for forming the at least one alignment mark are exposed to light in an identical step of exposing to light.

Further, a method of manufacturing a light emitting device according to certain embodiment of the present disclosure includes: the method of manufacturing a substrate; mounting light emitting elements to bond at least one light emitting element each including a p-side electrode and an n-side electrode on an identical surface side in each of the unit mounting regions, wherein the p-side electrode is bonded to an upper surface of corresponding one of the first projection parts, and the n-side electrode is bonded to an upper surface of corresponding one of the second projection parts.

The above-described methods of manufacturing substrates according to certain embodiment of the present disclosure provides a substrate with which the cutting positions are highly accurately adjustable relative to the mounting positions of the reference light emitting elements.

Further, the above-described methods of manufacturing a light emitting device according to the embodiment of the present disclosure can provide a light emitting device having advantages of cost-efficient and small in size.

DETAILED DESCRIPTION OF EMBODIMENT

In the following, a description will be given of an embodiment of the present disclosure with reference to the drawings.

First Embodiment

A first embodiment relates to a substrate10for a light emitting device in which unit mounting regions each including a wiring to be connected to a light emitting element, and a method of manufacturing the substrate10.

Substrate for Light Emitting Device According to First Embodiment

The substrate10for a light emitting device according to the first embodiment includes a base member15on whose one main surface a plurality of unit mounting regions is collectively provided. Each unit mounting region includes at least one first wiring part and at least one second wiring part. In the example shown inFIG. 1, each unit mounting region includes a pair of first wiring1and second wiring2provided to facing each other on one main surface. A light emitting element is mounted for each unit mounting region. The unit mounting regions are arranged in a matrix of 6 rows×3 columns. Alignment marks3are provided along one side of the base member15so as to correspond to respective rows in which the unit mounting regions are arranged in the lateral direction in a top view. The alignment marks3may be, for example, each an opening formed by removing a metal film formed on the surface of the base member in a predetermined shape such as an angular shape, rectangular shape, a circular shape, an oval shape or the like, whereby the surface of the base member15is exposed. In the substrate10according to the first embodiment, the metal film around the alignment marks3where the surface of the base member15is exposed has a thickness in Z direction increased to form metal frames3aaround the alignment marks3, so that the alignment marks3are easily recognized.

In the following description, the columns in each of which the unit mounting regions are arranged in the vertical direction in a top view are referred to as the first column, the second column, and the third column, from the side close to the alignment marks3.

The unit mounting regions may be arranged so as to form one row or one column. The unit mounting regions are preferably arranged in a matrix of a plurality of rows and columns. Further, in the present disclosure, one of the column direction and the row direction may be referred to as one direction.

Further, in each unit mounting region, the first wiring1includes a first wiring part1band a first projection part1aformed on the first wiring part1b, and the second wiring2includes a second wiring part2band a second projection part2aformed on the second wiring part2b. The first projection part1aand the second projection part2aare provided so as to respectively face a p-side electrode31and an n-side electrode32of a light emitting element when the light emitting element is mounted. As described above, by providing the first projection part1aand the second projection part2arespectively on the first wiring part1band the second wiring part2b, in mounting a light emitting element, the light emitting element can be mounted with high positional accuracy relative to the first projection part1aand the second projection part2ausing the self-alignment effect based on the first projection part1aand the second projection part2a.

In the substrate10according to the first embodiment, through slits S are respectively provided to penetrate through the base member15, between the column in which the alignment marks3are arranged and the first column of the unit mounting regions, between the first column and the second column, between the second column and the third column, and on the outer side of the third column. Here, each first wiring part1band each second wiring part2bextend along the lateral surface of each through slit S and part of the other main surface (i.e., the lower surface) of the base member15, and these first wiring part1band second wiring part2bat part of the other main surface configure external connection electrodes of the light emitting device. Further, inFIG. 1, the broken lines represent cutting lines C10along which the substrate10is cut after a plurality of light emitting devices each including a light emitting element is collectively fabricated on the substrate10. As can be understood from the foregoing, in the substrate10, each unit mounting region is defined by a region surrounded by the through slits S and the cutting lines C10.

In the substrate10for a light emitting device according to the first embodiment, each alignment mark3is formed with high positional accuracy relative to the first projection part1aand the second projection part2aparticularly by being fabricated through the manufacturing method described below. In this manner, after a plurality of light emitting devices is collectively fabricated on the substrate10, the substrate can be cut by setting it at the cutting position with reference to each alignment mark3formed with high positional accuracy relative to the first projection part1aand the second projection part2a. Thus, the substrate can be cut with the cutting position set precisely relative to each mounted light emitting element. Accordingly, when a light emitting device including a light emitting element is manufactured using the substrate10for a light emitting device according to the first embodiment, the interval between the lateral surface of the light emitting element and the cutting position can reliably be obtained with high accuracy and can be set to a minimum required distance. Hence, downsizing of the light emitting device is achieved.

Exemplary Structure of Light Emitting Device Fabricated Using Substrate10According to First Embodiment

FIG. 2is a sectional view showing the structure of the light emitting device100fabricated using the substrate10for a light emitting device according to the first embodiment. InFIG. 2, although the width direction is defined as the X direction, the thickness direction is defined as the Y direction, and the front-rear (i.e., depth) direction is defined as the Z direction, the X direction corresponds to the row direction of the substrate10, the Y direction corresponds to the column direction of the substrate10, and the Z direction corresponds to the thickness (height) direction of the substrate10.

The light emitting device100shown inFIG. 2includes a singulated substrate piece101, a light emitting element30, a light-transmissive member50, and a covering member70. The singulated substrate piece101is obtained as a result of the substrate10being cut. The singulated substrate piece101includes the first wiring1including the first projection part1aon the first wiring part1b, and the second wiring2including the second projection part2aon the second wiring part2b. The light emitting element30includes the p-side electrode31and the n-side electrode32on an identical surface side. The light emitting element30is flip-chip mounted so that the p-side electrode31is connected to the first projection part1avia a conductive adhesive member20, and the n-side electrode32is connected to the second projection part2avia the conductive adhesive member20. In the light emitting element30, the surface opposite to the surface where the p-side electrode31and the n-side electrode32are formed is the light emitting surface. Further, the light emitting element30is a light emitting diode chip being longer in the X direction and shorter in the Y direction. The light-transmissive member50is a rectangular parallelepiped-shaped piece longer in the X direction and shorter in the Y direction. For example, the light-transmissive member50is greater in size than the light emitting element30, and bonded to the light emitting surface of the light emitting element30via a light guide member40. The light-transmissive member50contains a wavelength conversion substance60containing a first fluorescent material61and a second fluorescent material62in a base material55. The covering member70is a reflective member containing white pigment77in a base material75, and covers the lateral surfaces of the light emitting element30on the singulated substrate piece101, the lateral surfaces of the light guide member40, and the lateral surfaces of the light-transmissive member50. The covering member70covers the lateral surfaces of each of the light emitting element30, the light-transmissive member50and the like over their entire perimeter. Further, the upper surface of the light-transmissive member50and the upper surface of the covering member70are substantially flush with each other.

In the light emitting device100structured as described above, light laterally emitted from the light emitting element30and the light-transmissive member50is reflected by the covering member70, and output upward (i.e., Z direction) and, hence, the light extraction efficiency in the upward (i.e., Z direction) direction improves. With the light emitting device100of such a structure, the covering member70needs to be formed to have a certain thickness in order to reduce the amount of light pass through the covering member70and increase the amount of light reflected by the covering member70. Here, if the positional accuracy of the cutting position relative to the mounting position of the light emitting element30and the light-transmissive member50is poor, the covering member70must be formed to have a great thickness more than necessary taking into consideration of variance in the positional accuracy of the cutting position and, hence, downsizing is limited. On the other hand, when the light emitting device100is manufactured using the substrate10for a light emitting device according to the first embodiment, the positional accuracy of the cutting position relative to the mounting position of the light emitting element30improves. This improvement eliminates the necessity of forming the covering member70to have a great thickness more than necessary, and makes it possible to manufacture a light emitting device being small in size.

Method for Manufacturing Substrate for Light Emitting Device According to First Embodiment

In the following, a description will be given of a method of manufacturing a substrate for a light emitting device according to the first embodiment.

(1) Providing Base Member

The base member15is provided with its shape set based on the number of pieces of light emitting devices formed on the substrate10and the final shape of each of the light emitting devices (shown inFIG. 3A). Specifically, the planar shape of the base member15is set based on the yields of the light emitting devices per base member15and the planar shape of individual light emitting devices, and the thickness of the base member is set based on the height of the light emitting devices. The base member15may be made of resin or fiber-reinforced resin, ceramic, glass or the like. Examples of the resin or fiber-reinforced resin include epoxy, glass epoxy, bismaleimide triazine (BT), polyimide or the like. Examples of the ceramic include aluminum oxide, aluminum nitride, zirconium oxide, zirconium nitride, titanium oxide, titanium nitride, or a mixture of the foregoing substances. The base member15may be flexible and, for example, may be formed using polyimide, polyethylene terephthalate, polyethylene naphthalate, liquid crystal polymer, cyclo olefin polymer or the like, each being flexible. Among these examples, use of the material having physical properties such as a linear expansion coefficient similar to the linear expansion coefficient of the light-emitting element is particularly preferable. With such a base member, there is less possibility of breakage of the light emitting element attributed to the difference in coefficient of thermal expansion from the base member. The coefficient of linear expansion of the base member15is preferably 15 ppm/° C. or less, more preferably 10 ppm/° C. or less. The lower limit value of the coefficient of linear expansion of the base member15is, for example, 1 ppm/° C. or more. Although the coefficient of linear expansion of the light emitting element differs depending on the type of the employed semiconductor material or the like, it is close to the coefficient of linear expansion of the material having the dominant volume in the light emitting element. Accordingly, when the light emitting element includes a sapphire substrate, normally the volume of the sapphire substrate is dominant. Therefore, the coefficient of linear expansion of the light emitting element is close to the coefficient of linear expansion of the sapphire substrate, and is about 7.7 ppm/° C., for example. When the light emitting element does not include a sapphire substrate and is structured by a semiconductor layer alone, the coefficient of linear expansion of the light emitting element is close to the coefficient of linear expansion of the employed semiconductor layer. The coefficient of linear expansion of a light emitting element made of a GaN-based semiconductor layer is about 5.5 ppm/° C., for example. The base member15having the coefficient of linear expansion of 10 ppm/° C. or less is less likely to be subject to deformation by heat. Thus, the positional accuracy of the first projection part, the second projection part and/or the alignment mark formed on the base member improves.

Subsequently, the through slits S penetrating through the base member15may be respectively formed between the region where the alignment marks are arranged in the vertical direction (i.e., Y direction) and the region of the first column where unit mounting regions are arranged, between the region of the first column where the unit mounting regions are arranged and the region of the second column where the unit mounting regions are arranged, between the region of the second column where the unit mounting regions are arranged and the region of the third column where the unit mounting regions are arranged, and outside the region of the third column where the unit mounting regions are arranged. Such formation of slits S can be performed, for example, by a router processing and/or a laser processing. For example, the through slits S are preferably respectively formed outside the outermost columns out of the columns of the unit mounting regions and between the columns of the unit mounting regions. Thus, by virtue of the through slits S being positioned on both sides of the unit mounting regions, cutting the base member is facilitated. In the case where the through slits are provided, preferably the first wiring part and the second wiring part are each formed to extend to the lower surface of the base member via the inner surfaces of each through slit. In this manner, the bonding strength of the first wiring part and the second wiring part to the base member improves. The opposite ends of the through slit S are spaced apart from the lateral surfaces of the base member. Thus, the plurality of unit mounting regions is supported by the outer peripheral part of the base member15, after the through slits S are formed.

(3) Forming Metal Film Wiring

Subsequently, a metal film wiring11for forming the first wiring part and the second wiring part is formed on the surface of the base member15including one main surface (i.e., the upper surface) and other main surface (i.e., the lower surface) of the base member15and the lateral surface of the through slit S (shown inFIG. 3B). In the manufacturing method according to the first embodiment, as shown inFIG. 3B, the metal film wiring11is formed over the entire surface of the base member15including the regions where the alignment marks are formed. The metal film wiring11is formed to have a predetermined thickness by, for example, forming an electrolytic copper-plating layer on an electroless copper-plating layer. Although the thickness of the metal film wiring11is set as appropriate depending on the light emitting device to be manufactured, for example, the thickness may be in a range of 5 μm to 30 μm, preferably 10 μm to 25 μm, more preferably 15 μm to 20 μm. The material of the metal film wiring11may also be selected as appropriate depending on the light emitting device to be manufactured, but preferably the material is a metal material such as copper, nickel or the like.

(4) Performing First Photolithography

4-1. Forming First Resist Forming

Firstly, resist R11is applied over the entire metal film wiring11(shown inFIG. 3C). The resist R11may be, for example, dry film resist which is cured by exposure to light. The dry film resist may be, for example, a carrier film, a photosensitive layer, or a cover film. The carrier film may be PET, the photosensitive layer may be acrylic resin, and the cover film may be polyethylene. The carrier film and the cover film may each have a thickness in a range of, for example, 20 μm or more to 50 μm or less.

4-2. First Exposing to Light

Subsequently, for example, based on the wiring pattern data for the first wiring part1band the second wiring part2b, the resist R11is directly irradiated with light, so that the portions corresponding to the first wiring part1band the second wiring part2b(i.e., the portions positioned on the first wiring part1band the second wiring part2b) are cured. Although the example using a direct imaging device for directly irradiating the resist R11with light based on the wiring pattern data is described here, light exposure may be performed via a mask in which patterns corresponding to the first wiring part1band the second wiring part2bare formed.

4-3. First Developing

Subsequently, the resist R11that has not been cured is removed. For example, a developing solution such as trichloroethane, an NaOH aqueous solution or the like may be used. By this development, the resist R11formed to have the patterns corresponding to the first wiring part1band the second wiring part2bis formed (shown inFIG. 3D).

4-4. Metal Film Removing Operation

Subsequently, by etching the metal film wiring11using the patterned resist R11, the first wiring part1band the second wiring part2bare formed (shown inFIG. 3E). Preferably, the first wiring part and the second wiring part are formed so that the unit mounting regions are arranged in one direction. This manner contributes toward increasing the yields of the singulated substrate pieces per substrate. Further, preferably, the first wiring part and the second wiring part are formed so that a plurality of columns in each of which the unit mounting regions are arranged in one direction is juxtaposed to one another in the direction perpendicular to the one direction. This manner further contributes toward increasing the yields of the singulated substrate pieces per substrate. In the present disclosure, perpendicular refers to an angle of 90±5°.

The portion where each alignment mark3is formed is preferably an opening formed by part of the metal film wiring11being removed, whereas the base member15is exposed. As a result, a portion where the base member15is exposed serves as the alignment mark3, therefore, the device is easily recognized in steps of Processing Light-transmissive Member or Singulation described later, based on the difference in appearance between the exposed portion of the base member and a metal frame3asurrounding the exposed portion.

By the above-described first photolithography operation, the first wiring part1band the second wiring part2bare formed. Although the above-described example uses a so-called negative type resist in which an exposed portion is remained after the exposure to light and the removal, it is also possible to use a positive type resist in which an exposed portion is removed after the exposure and the removal.

(5) Metal Film Projection Forming Operation

Subsequently, a metal film projection12for forming the first projection part, the second projection part, and the metal frame surrounding the alignment mark is formed on or above the surface of the base member15including one main surface and other main surface of the base member15and the lateral surfaces of the through slits (shown inFIG. 3F). As shown inFIG. 3F, as to the portions where the first wiring part1band the second wiring part2bare not formed, the metal film for projection12is directly formed at the surface of the base member15. As to the portions where the first wiring part1band the second wiring part2bare formed, the metal film projection12is formed above the surface of the base member15via the first wiring part1band the second wiring part2b. In the present manufacturing method according to the first embodiment, the metal film projection12is formed over the entire surface of the base member15including the region where the alignment marks are formed. A metal film for metal frame surrounding each alignment mark may however be formed in an operation other step for forming the metal film projection. In the case where the metal frame-purpose metal film is formed in other step for forming the metal film, the metal film projection is referred to as the first metal film, and the metal film for metal frame is referred to as the second metal film. In other words, the metal film projection12in the metal film forming operation according to the first embodiment corresponds to the first metal film and the second metal film being formed in an identical metal film forming operation. Further, the metal film projection is formed to have a predetermined thickness by, for example, performing electrolytic copper-plating on an electroless copper-plating layer. The metal film projection12is formed to have a thickness in a range of, for example, 8 μm to 50 μm, preferably 10 μm to 40 μm, more preferably 15 μm to 30 μm. The material of the metal film projection12may be selected as appropriate depending on the manufactured light emitting device, the material is however preferably a metal material such as copper, nickel or the like.

6-1. Forming Second Resist Forming

Resist R12is applied over the entire metal film projection12(shown inFIG. 3G). The resist R12may be, for example, dry film resist which is cured after exposure to light. The dry film resist may be a member similar to those described above. The resist for forming the first projection part and the second projection part is used for a projection part forming-purpose resist, and the resist for forming the alignment mark is used for an alignment mark forming-purpose resist, so that the resist R12includes the projection part forming-purpose resist and the resist for forming alignment mark.

6-2. Second Exposing to Light

Subsequently, for example, based on the pattern data for the first projection part, the second projection part, and the metal frame surrounding the alignment mark, the resist R12is directly irradiated with light, so that the portions corresponding to the first projection part, the second projection part, and the metal frame are cured (shown inFIG. 3H). This direct imaging of directly irradiating the resist R12with light is performed as a series of continuous light irradiation, for example, without resetting the irradiation position between irradiation for the first projection part pattern and irradiation for the second projection part pattern, and between irradiation for the first projection part and/or second projection part pattern and irradiation for the metal frame3apattern. In other words, the resist for forming projection part and the resist for forming alignment mark are exposed in an identical step of exposing to light. Although the manufacturing method according to the first embodiment exemplifies direct imaging, exposure may be performed via a photomask in which patterns respectively corresponding to the first projection part, the second projection part, and the metal frame are collectively formed.

6-3. Second Developing

Subsequently, the resist R12that has not been cured is removed (shown inFIG. 3I). For example, the developing solution may be a solution similar to those noted above. By this development, the resist R12formed to have the patterns corresponding to the first projection part1a, the second projection part2a, and the metal frame3ais formed.

6-4. Removing Metal Film Projection

Subsequently, by etching the metal film projection12using the patterned resist R12, the first projection part1a, the second projection part2a, and the metal frame3aare formed (shown inFIG. 3J). In the present manufacturing method according to the first embodiment, the first projection part1a, the second projection part2a, and the metal frame3aare formed using the resist R12. Alternatively, the resist for forming the first projection part and the second projection part, and the resist for forming the alignment mark to form the metal frame3amay however be different from each other. The resist for forming projection part and the resist for forming alignment mark may be exposed in an identical step of exposing to light.

The first projection part1a, the second projection part2a, and the metal frame3aare formed by the above-described second photolithography operation. In the second exposing operation in the second photolithography operation, irradiation corresponding to the pattern of the first projection part1a, irradiation corresponding to the pattern of the second projection part2a, and irradiation corresponding to the pattern of the metal frame3aare performed by a series of continuous light irradiation. Therefore, each alignment mark can be formed with high positional accuracy relative to the first projection part1aand the second projection part2a. Further, in the manufacturing method according to the first embodiment, in the case where exposure to light is performed via a photomask in which patterns respectively corresponding to the first projection part1a, the second projection part2a, and the metal frame3aare collectively formed also, similarly, each alignment mark is formed with high positional accuracy relative to the first projection part1aand the second projection part2a. In the case where the unit mounting regions are arranged in one direction, preferably the alignment marks are formed in one direction so as to each correspond to corresponding ones of the unit mounting regions. This manner makes it easier to form the alignment marks in a narrow space.

A description will be given below for a method of manufacturing the light emitting device100according to the first embodiment with reference toFIGS. 4A to 4E.FIGS. 4A to 4Eare each an end view in the column direction of the substrate10on which the unit mounting regions are arranged, each showing the first wirings1.

Mounting Light Emitting Element

In the step of mounting light emitting element, as shown inFIG. 4A, each light emitting element30is flip-chip mounted on the substrate10. Specifically, the paste-like conductive adhesive member20is applied onto the first projection part1aand the second projection part2a. The light emitting element30is mounted such that the p-side electrode31and the n-side electrode32of the light emitting element30respectively face the first projection part1aand the second projection part2a. The conductive adhesive member20is heated with a reflow oven or the like thereby molten. Thereafter, the conductive adhesive member20is cooled so as to be cured. At this time, the light emitting element30is mounted with high accuracy relative to the first projection part1aand the second projection part2aby the self-alignment effect brought about by the first projection part1aand the second projection part2a. Here, the conductive adhesive member20is, for example, solder.

Bonding Light-Transmissive Member

In the step of bonding light-transmissive member, as shown inFIG. 4B, each light-transmissive member50is bonded to each light emitting element30. Specifically, the light guide member40in the liquid state is applied onto the light emitting element30, and the light-transmissive member50is mounted thereon. Then, the light guide member40is caused by a heating process. In the following, “the liquid state” as used in the present disclosure includes the sol state and the slurry state.

Processing of Light-Transmissive Member

In the step of processing light-transmissive member, as shown inFIG. 4C, the lateral surfaces of the light-transmissive member50is cut to make the light-transmissive member50a predetermined dimension. Specifically, for example, the lateral surface of one of adjacent light-transmissive members50and the lateral surface of the other one of the adjacent light-transmissive members50are cut simultaneously, for example, by rotating a rotary blade having a predetermined thickness to run in the X direction and the Y direction while rotating. Thus, the light-transmissive member50for each light emitting device is processed to have a predetermined shape. In rotating the rotary blade, the rotary blade is positioned with reference to the alignment marks. Here, in the substrate according to the first embodiment, each alignment mark is formed with high positional accuracy relative to the first projection part and the second projection part, and the light emitting element is mounted at high positional precision relative to the first projection part and the second projection part by virtue of the self-alignment effect. Thus, the rotating the rotary blade can be performed having the rotary blade precisely aligned with the light emitting element. Accordingly, the light emitting element on which the light-transmissive member50is disposed can be processed with high accuracy.

Forming of Covering Member

In the step of forming covering member, as shown inFIG. 4D, for example, the space around the light emitting element30and the light-transmissive member50on the substrate is filled with the covering member70in the liquid state, and the covering member70is heated to be cured. Thus, the light-reflective covering member70covering the light-transmissive member50and the light emitting element30on the substrate is formed on the substrate. Here, for example, the covering member70is formed and cured such that the light-transmissive member50is completely embedded in the covering member70, followed by exposing the upper surface of the light-transmissive member50from the covering member70by grinding or blasting. Here, the covering member70is preferably formed so as to avoid the alignment mark3from being covered. In this manner, the covering member is formed around the light emitting elements30while embedding the light emitting elements30, and avoiding the alignment marks3from being covered.

In the step of singulation, as shown inFIG. 4E, the substrate and the covering member70are cut with a cutting blade, so that covering member70covering the lateral surfaces of the light-transmissive member50and the lateral surfaces of the light emitting element30by a predetermined width is formed. In cutting the substrate and the covering member70, the cutting position is set by positioning the cutting blade with reference to the alignment marks. Here, in the substrate10according to the first embodiment, each alignment mark is formed with high positional accuracy relative to the first projection part1aand the second projection part2a, and each light emitting element is mounted with high positional accuracy by virtue of the self-alignment effect relative to the first projection part and the second projection part. Hence, the substrate10and the covering member70can be cut to obtain individual light emitting devices with high accuracy relative to the light emitting elements30and/or the light-transmissive members50. In the case where the unit mounting regions are arranged in one direction, the substrate10and the covering member70are cut in the direction perpendicular to one direction, so that the substrate10and the covering member70are separated into individual light emitting devices each including at least one light emitting element.

As has been described above, in the method of manufacturing the light emitting device100according to the first embodiment, the light emitting device100is manufactured using the substrate10in which each alignment marks3are formed with high positional accuracy relative to the first projection parts1aand the second projection parts2a. Therefore, the positional accuracy of the cutting position relative to the mounting position of the light emitting element30improves. This improvement eliminates the necessity of forming the covering member70to have a great thickness more than necessary, and makes it possible to manufacture a light emitting device being small in size.

Further, each alignment mark3is formed with high positional accuracy relative to the first projection part1aand the second projection part2aon which the light emitting element30is to be mounted, and the light-transmissive member50disposed on the light emitting element30is formed relative to the alignment mark3. This manner improves the positional accuracy between the light-transmissive member50after the step of processing and the cutting position. As shown inFIG. 4Ffor example, this improvement eliminates the necessity of forming the covering member70covering the lateral surfaces in the longitudinal direction of the light-transmissive member50to have a great thickness more than necessary, and makes it possible to manufacture a light emitting device being small in size.

In the substrate for the light emitting device100and the method of manufacturing the light emitting device100according to the first embodiment, each alignment mark3is disposed between the cutting lines C10. However, in the substrate for the light emitting device100and the method of manufacturing the light emitting device100according to the first embodiment, each alignment mark3may be disposed on the cutting line C10. Specifically, as shown inFIG. 5, for example, each alignment mark3may be disposed such that the center line of the alignment mark3in the longitudinal direction and the cutting line C10overlap with each other in a top view. This structure makes it possible to highly accuracy set the cutting position with reference to each alignment mark3.

In the substrate for the light emitting device100and the method of manufacturing the light emitting device100according to the first embodiment, although the alignment mark3is provided for each row of the first wiring and the second wiring, for example, one alignment mark3may be provided for a plurality of rows. This structure can simplify the exposure pattern. In this structure, the device is positioned recognizing one alignment mark3, followed by processing the plurality of rows. Thus, it becomes possible to reduce the number of times of recognizing the alignment mark3and positioning the device for a plurality of rows of the substrate, and to improve mass productivity.

In the substrate for the light emitting device100and the method of manufacturing the light emitting device100according to the first embodiment, although each alignment mark3is a recess surrounded by the metal frame, each alignment mark3may be a projection formed by the metal film for projection or the second metal film. Each alignment mark3is preferably a recess in view of alleviating delamination or loss of adhesion of the alignment mark3.

Although the light emitting device100according to the first embodiment includes one light emitting element30, a plurality of light emitting elements30may be mounted in the light emitting device. With this structure, the amount of light extracted from one light emitting device can be increased. In this case, the substrate preferably includes the first wiring, the second wiring, the first projection parts, and the second projection parts respectively corresponding to the plurality of light emitting elements.

As shown inFIG. 2, the light emitting device100according to the first embodiment has a structure in which the lateral surfaces of the covering member and the lateral surfaces of the singulated substrate piece are located on planes different from each other in the width direction of the light-transmissive member, so that a stair-step is formed at the lateral surface of the light emitting device between the lateral surface of the covering member and the lateral surface of the singulated substrate piece. However, as in Variation shown inFIG. 6, the lateral surfaces of the covering member and the lateral surfaces of the singulated substrate piece may be positioned at a substantially identical plane in the width direction (i.e., the X direction) of the light-transmissive member, so that no stair-step is formed at the lateral surface of the light emitting device. Further, in a light emitting device200of Variation shown inFIG. 6, for example, instead of the first wiring part and the second wiring part at the lateral surfaces of the singulated substrate piece101, through holes are formed at the singulated substrate piece101. Through wirings respectively formed on the through holes connect the first wiring1and the second wiring2formed on/above the upper surface of the singulated substrate piece101to the first wiring1(i.e., the first external connection electrode) and the second wiring2(i.e., the second external connection electrode) formed on/above the lower surface of the singulated substrate piece101. In this manner, positioning the lateral surfaces of the covering member and the lateral surfaces of the singulated substrate piece substantially at an identical plane in the width direction (i.e., the X direction) of the light-transmissive member can achieve downsizing of the light emitting device. InFIG. 6, members expressed by the reference numerals1cand2care resin with which the through holes are filled. In order to position the lateral surfaces of the covering member and the lateral surfaces of the singulated substrate piece substantially at an identical plane as in the light emitting device200of Variation shown inFIG. 6, for example, the lateral surfaces of the covering member and the lateral surfaces of the singulated substrate piece should be continuously cut with the cutting blade in the step of singulation. In the present disclosure, “positioning substantially at an identical plane” may include a height difference of tolerance of about ±10 μm.