Method of manufacturing light emitting device

A method of manufacturing a light emitting device includes: providing on a mounting substrate a soluble member which is soluble in a solvent and which has a lower surface, an upper surface opposite to the lower surface in a height direction, and an outer side surface provided between the lower surface and the upper surface, the lower surface contacting the mounting substrate; providing a light blocking member made of resin to cover the outer side surface of the soluble member so that an inner side wall of the light blocking member contacts the outer side surface of the soluble member; removing the soluble member using the solvent to provide a recess surrounded by the inner side wall of the light blocking member; and mounting a light emitting element in the recess.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2015-163422, filed Aug. 21, 2015, entitled “Method of manufacturing a light emitting device”. The contents of this application are incorporated herein by reference in their entirety.

BACKGROUND

Technical Field

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

Discussion of the Background

Light emitting diodes (LEDs) have been used as a backlight source of a display panel of an electronic device. Especially, in recent years, as the electronic device is increasingly thinned and its screen is enlarged, the display panel and a light guide plate are required to be thinned and increased in a screen size, so that the LED is also required to be thinned and achieve a higher output.

Japanese Unexamined Patent Application Publication No. 2006-253551 discloses a method of manufacturing a light emitting device having a reflection case, a terminal member embedded in the reflection case and a light emitting element mounted in a recess portion of the reflection case having an opening on a front side. This reflection case may be formed by resin molding with the terminal member sandwiched by a die.

SUMMARY

According to one aspect of the present disclosure, a method of manufacturing a light emitting device includes: providing on a mounting substrate a soluble member which is soluble in a solvent and which has a lower surface, an upper surface opposite to the lower surface in a height direction, and an outer side surface provided between the lower surface and the upper surface, the lower surface contacting the mounting substrate; providing a light blocking member made of resin to cover the outer side surface of the soluble member so that an inner side wall of the light blocking member contacts the outer side surface of the soluble member; removing the soluble member using the solvent to provide a recess surrounded by the inner side wall of the light blocking member; and mounting a light emitting element in the recess.

According to another aspect of the present disclosure, a method of manufacturing a light emitting device includes: providing each of soluble members on each of mounting substrates, each of the soluble members being soluble in a solvent and having a lower surface, an upper surface opposite to the lower surface in a height direction, and an outer side surface provided between the lower surface and the upper surface, the lower surface contacting each of the mounting substrates; providing light blocking members made of resin, each of the light blocking members covering the outer side surface of each of the soluble members so that an inner side wall of each of the light blocking members contacts the outer side surface of each of the soluble members; removing the soluble members using the solvent to provide recesses, each of the recesses being surrounded by the inner side wall of each of the light blocking members; and mounting each of light emitting elements in each of the recesses.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a light emitting device and a method of manufacturing a light emitting device in an embodiment will be described.

Furthermore, since the embodiment is schematically illustrated in the drawings to be referred to, in the following description, a dimension of a member, and a distance and a positional relationship between them are occasionally exaggerated, or illustration of the member is occasionally partially omitted. Furthermore, dimensions of members and distances between them differ between a planer view and a cross-sectional view in some cases. Furthermore, in the following description, the same or similar member is basically marked with the same name or reference, and its detailed description is appropriately omitted.

First Embodiment

Configuration of Light Emitting Device

First, a configuration of a light emitting device in the first embodiment will be described with reference toFIGS. 1A to 1C.

A light emitting device100in the first embodiment includes a semiconductor light emitting element1(hereinafter, referred to as the light emitting element), a light blocking member2, a sealing member3, and a mounting substrate (that is, sub-mount)4.

The light blocking member2is provided on an upper surface of the mounting substrate4and has a recess portion2a(a recess2a) serving as an opening on that upper surface. In the recess portion2a, the light emitting element1is flip-chip mounted with an electrically-conductive bonding member43such as solder. The light-transmissive sealing member3is provided in the recess portion2ato cover an upper surface and outer side surface of the light emitting element1. Light emitted from the light emitting element1can pass through the sealing member3, and can be externally extracted from the opening of the recess portion2aof the light blocking member2.

Next, a configuration of each component of the light emitting device100will be sequentially described in detail.

The light emitting element1has a substantially cuboidal shape having a horizontally long rectangular shape in planar view. The light emitting element1serves as an LED chip suitable for the flip-chip mounting, in which an n-side electrode13and a p-side electrode15are provided on one surface and bonded to wiring electrodes42nand42pof the mounting substrate4serving as the sub-mount through the conductive bonding member43.

The light emitting element1is mounted in the recess portion2aserving as a cavity in which its bottom surface is composed of the upper surface of the mounting substrate4, and its side wall is composed of the light blocking member2. Furthermore, the light emitting element1is sealed with the sealing member3provided in the recess portion2a.

Here, a configuration example of the light emitting element1will be described with reference toFIG. 2in detail. In addition, inFIG. 2, the surface provided with the n-side electrode13and the p-side electrode15faces upward, which is opposite toFIG. 1C. Furthermore, the configuration of the light emitting element1is simply illustrated inFIGS. 1A to 1CandFIGS. 8A to 10Bdescribed below.

The light emitting element1includes a substrate11, a semiconductor laminated body12, the n-side electrode13, an overall electrode14, the p-side electrode15, and an insulating film16. The semiconductor laminated body12of the light emitting element1has an LED structure in which an n-type semiconductor layer12n, an active layer12a, and a p-type semiconductor layer12pare laminated on one main surface of the substrate11. The semiconductor laminated body12emits light when the n-side electrode13and the p-side electrode15are connected to an external power supply and turned on.

The semiconductor laminated body12has an exposed portion12bin which the p-type semiconductor layer12pand the active layer12aare not partially provided, that is, the n-type semiconductor layer12nis exposed on an upper surface serving as an electrode-forming surface in the semiconductor laminated body12. The n-side electrode13is provided in the exposed portion12band electrically connected to the n-type semiconductor layer12n. Furthermore, the overall electrode14having favorable electrical conductivity and light-blocking property is provided on an almost whole upper surface of the p-type semiconductor layer12p. Still furthermore, the surface of the semiconductor laminated body12is covered with the insulating film16directly or through the overall electrode14except for a part of an upper surface of the exposed portion12band a part of an upper surface of the overall electrode14.

The semiconductor laminated body12(the n-type semiconductor layer12n, the active layer12a, and the p-type semiconductor layer12p) is favorably made of nitride semiconductor expressed by InXAlYGa1−X−YN (0≦X, 0≦Y, X+Y≦1). Furthermore, each of the substrate11, the n-side electrode13, the overall electrode14, the p-side electrode15, and the insulating film16is made of material favorably used in this field as well as the semiconductor laminated body12.

The light emitting element1illustrated inFIG. 2is only one example, and its outline shape, and disposed regions of the exposed portion12b, the n-side electrode13, and the p-side electrode15can be appropriately changed.

Furthermore, the light emitting element1may be a chip size package (CSP) or chip scale package (CSP) type in which a support layer made of a material such as a resin is provided on the electrode-forming surface, and an external connecting metal terminal such as metal bump or post electrode is formed on the n-side electrode13and the p-side electrode15. In this case, the support layer to be provided on the electrode-forming surface of the light emitting element1is preferably a resin member containing a light-reflective material. Thus, the light leaked from the electrode-forming surface can be reflected toward the opposite surface, so that light extraction efficiency from the light emitting element1can be improved.

Furthermore, the light emitting element1may not have the substrate11.

Returning toFIGS. 1A to 1Cagain, the description of the configuration of the light emitting device100will be continued.

The light blocking member2has the recess portion2awhich is provided on the upper surface of the mounting substrate4to mount the light emitting element1. The recess portion2ahas the opening on the upper surface and the opening is larger than the outline of the light emitting element1in planer view. Therefore, not only the upper surface but also the outer side surface of the light emitting element1can be covered with the sealing member3provided in the recess portion2a.

The light blocking member2is a member which can block light. The light blocking member2may be made of light-reflective material which blocks the light by reflecting the light, or light-absorbing material which blocks the light by absorbing the light.

In the case where the light blocking member2is made of a light-reflective material, the light blocking member2reflects the light emitted from the upper surface and the outer side surface of the light emitting element1and passed through the sealing member3, and concentrates it in the opening of the recess portion2aso that the light can be externally extracted. Thus, light emission brightness from the upper surface of the light emitting device100can be improved.

In the case where the light blocking member2is made of light-absorbing material, the light blocking member2absorbs the light emitted from the outer side surface of the light emitting element1and entering the light blocking member2. Therefore, the light can be emitted only from the upper surface of the light emitting device100.

Since the light blocking member2is provided, whether the light blocking member2is made of a light-reflective material or a light-absorbing material, emitting the light from the light emitting device100can be limited from the opening of the recess portion2aof the light blocking member2, so that the light emitting device100can be high in contrast between a light emitting region and a light non-emitting region, that is, its visibility can be improved.

When the light emitting device in this embodiment is used in a backlight device or an illumination device, the following merits are provided.

In a case where the light emitting device is used in a backlight device in which a light guide plate has a light incident end lateral surface, by using the light emitting device100increased in front surface brightness, light incident efficiency to the end lateral surface of the light guide plate is enhanced, whereby it is possible to enhance efficiency of the light used as a backlight illumination light.

Furthermore, in a case where the light emitting device is used in a direct type backlight device in which a light guide plate has a light incident end lateral surface is not used, light distribution control can be easily performed with a secondary lens by using the light emitting device100having small light emission area. Thus, it is possible to reduce brightness unevenness and color unevenness in the backlight illumination light.

Furthermore, when the light emitting device is used in a general illumination device, light distribution control can be easily performed with a lens by using the light emitting device100having small light emission area. Thus, when the plurality of light emitting devices100are mounted at a narrow pitch, light emitting from the light emitting devices100and being applied to and absorbed or blocked by the adjacent light emitting device100can be reduced. That is, the light emitted from the light emitting device100can be hardly affected by the adjacent light emitting device100. As a result, light use efficiency of the illumination device can be hardly affected by a light reflectivity of materials composing the light emitting device100such as a base material of the light blocking member2constituting the outline of the light emitting device100, so that a material of the base material can be selected from a variety of options.

The light-reflective material may include a light-reflective property-added resin material provided by mixing a resin having high light-transmissive and insulating properties, with particles of light-reflective substance. The resin can include an epoxy resin and a silicone resin. Furthermore, the light-reflective substance can include a material such as TiO2, Al2O3, ZrO2, and MgO.

Furthermore, the light-absorbing material may include a light-absorbing property-added resin material provided by mixing the same resin material as in the above, with particles of a light-absorbing substance. The light-absorbing substance includes black pigment and favorably includes carbon-based pigment such as carbon black or graphite.

The light blocking member2made of the resin material containing the light-reflective substance to have the light-reflective property or the resin material containing the light-absorbing substance to have the light-absorbing property as described above can be formed by a die molding method such as transfer molding, injection molding, or compression molding, or a coating method such as screen printing.

When the light-reflective material is used in the light blocking member2, the light from the light emitting element1can be externally extracted with high efficiency. When the light-absorbing material is used in the light blocking member2, resin having high moldability can be used, so that reliability of the light emitting device100can be enhanced.

As detailed description given below, the light blocking member2is provided in such a manner that a region for the recess portion2ais masked with a soluble member made of material which is dissolved in a solvent, the light blocking member2is formed to cover the soluble member, and then the soluble member is dissolved and removed by the solvent, so that the recess portion2acan be formed with high precision.

The sealing member3is provided in the recess portion2aas illustrated inFIGS. 1A to 1Cto seal the light emitting element1. The sealing member3is made of light-transmissive material and provided to cover the upper surface and the outer side surface, that is, the light emission surfaces of the light emitting element1. An outer surface of the sealing member3is in contact with the light blocking member2.

The sealing member3inFIG. 1Cis provided on the lower surface of the light emitting element1, but it may not be provided on the lower surface of the light emitting element1. The sealing member3can provided to cover the light emission surfaces of the light emitting element1, that is, the upper surface and the outer side surface of the substrate11and the side surface of the semiconductor laminated body12.

The sealing member3may be a wavelength conversion member made of a light transmissive resin containing a wavelength conversion substance which can convert the light emitted from the light emitting element1to the light having a different wavelength. Furthermore, the sealing member3may be a light-diffusing member made of a light transmissive resin containing a light-diffusing substance which diffuses the light emitted from the upper surface and the outer side surface of the light emitting element1. Furthermore, the sealing member3may be simply made of a light transmissive resin to protect the light emitting element1.

The wavelength conversion substance may be any fluorescent material. For example, the fluorescent material includes cerium-activated yttrium aluminum garnet (YAG)-based fluorescent material which emits green to yellow light, cerium-activated lutetium aluminum garnet (LAG)-based fluorescent material which emits green light, europium and/or chrome-activated nitrogen-containing calcium aluminosilicate (CaO—Al2O3—SiO2)-based fluorescent material which emits green to red light, europium-activated silicate ((Sr,Ba)2SiO4)-based fluorescent material which emits blue to red light, nitride-based fluorescent material such as β sialon (SiAlON) fluorescent material which emits green light, CASN-based or SCASN-based fluorescent material which emits red light, KSF (K2SiF6: Mn)-based fluorescent material which emits red light, and sulfide-based fluorescent material which emits green or red light.

The light-diffusing substance may be the same material as the above light-reflective substance.

The sealing member3may be made of a light transmissive resin containing a mixture of a plurality of kinds of wavelength conversion substances and light-diffusing substances.

The sealing member3can be formed by filling the recess portion2awith the resin material containing particles of the above-described wavelength conversion substance and/or light-diffusing substance to add various kinds of functions. The resin material may not contain the above-described particles.

The sealing member3can formed by a coating method such as spraying, screen printing, or potting (dropping), or a die molding method such as injection molding, transfer molding, or compression molding.

A functional substance such as wavelength conversion substance may include a fragile material such as KSF fluorescent material. When particles of the fragile fluorescent material are used, the fluorescent material particles could be damaged by the method such as spraying by which an impact is applied to the fluorescent material particles at the time of coating, or the method such as screen printing by which a pressure is applied to the fluorescent material particles.

Therefore, when the sealing member3is made of the resin material containing the fragile particles, the potting method is preferably used. By the potting method, when slurry containing the fluorescent material particles is applied, a high impact or pressure may not be applied to the particles of the fluorescent material, so that the damage of the fluorescent material particles can be reduced.

According to this embodiment, the sealing member3is provided in the recess portion2asurrounded by the light blocking member2. Therefore, even when the slurry or a liquid resin is applied by the potting method, the sealing member3can be disposed and formed with high precision.

The mounting substrate4is the substrate to mount the light emitting element1to be packaged. The mounting substrate4illustrated inFIGS. 1A to 1Cis composed of a plate-shaped base member41having a horizontally long rectangular shape in planar view, and the wiring electrodes42nand42pcontinuously provided from the upper surface to the back surface through the outer side surfaces of the base member41on the right and left of the base member41, respectively in a longitudinal direction.

The light blocking member2is provided on the upper surface of the mounting substrate4, the light emitting element1is mounted in the recess portion2aof the light blocking member2, and the sealing member3is provided in the recess portion2ato seal the light emitting element1.

The base member41may be made of insulating material and preferably made of material having a thermal linear expansion coefficient which is as low as that of the semiconductor laminated body12of the light emitting element1. When the base member41is made of the material having the low linear expansion coefficient, a stress applied to the light emitting element1may be low when the light emitting element1is flip-chip mounted by a reflow method, so that damage of the light emitting element1can be reduced.

The material having the low linear expansion coefficient includes a resin material containing glass fiber or glass cloth in a resin such as an epoxy resin, and a ceramic material.

The wiring electrodes42nand42pare wiring patterns provided on the surface of the base member41to correspond to a negative electrode and a positive electrode and have element mount portions42naand42paserving as regions for mounting the light emitting element1, respectively. The element mount portion42naand the element mount portion42paare provided in such a manner that their end portions face each other in a center of the upper surface of the base member41, and they are exposed from the light blocking member2in the bottom surface of the recess portion2a. The element mount portions42naand42pahave suitable shapes to mount the light emitting element1by flip-chip mounting in the recess portion2a.

The mounting substrate4has a size to inclusively mount the light blocking member2provided around the light emitting element1in planar view. The wiring electrode42nis bonded to the n-side electrode13of the light emitting element1in the element mount portion42na, and the wiring electrode42pis bonded to the p-side electrode15of the light emitting element1in the element mount portion42pa, with the electrically conductive bonding member43such as solder.

Regions of the wiring electrodes42nand42pprovided on an outer side of the light blocking member2in planer view are used when the light emitting device100is mounted on an external circuit substrate with a bonding member such as solder.

As for each of the wiring electrodes42nand42p, instead of being provided from the upper surface to the lower surface through the side surface of the base member41, a through hole may be formed in the base member41and filled with an electrically conductive material to connect its upper surface pattern to its lower surface pattern, or each of them may be formed only on the upper surface.

Operation of Light Emitting Device

Next, the operation of the light emitting device100in the first embodiment will be described with reference toFIGS. 1A to 1C.

In this embodiment, the light emitting element1emits blue light, and the sealing member3contains particles (wavelength conversion particles) of a fluorescent material (wavelength conversion substance) which absorbs the blue light and emits yellow light.

The light emitting element1in the light emitting device100emits the blue light when a current is supplied between the n-side electrode13and the p-side electrode15from the external power supply through the wiring electrodes42nand42pof the mounting substrate4.

The blue light emitted from the light emitting element1partially travels in the semiconductor laminated body12and the substrate11of the light emitting element1and enters the sealing member3from the upper surface and the outer side surface of the light emitting element1. The light which travels toward the electrode-forming surface in a lower direction in the light emitting element1, is reflected upwardly by the overall electrode14and the n-side electrode13, and enters the sealing member3from the upper surface or the outer side surface of the light emitting element1.

The blue light in the sealing member3is partially absorbed by the fluorescent material contained in the sealing member3, converted to the yellow light through wavelength conversion, and externally extracted from the light emitting device100. Furthermore, at least one part of the blue light in the sealing member3is externally extracted from the light emitting device100as the blue light without being absorbed by the fluorescent material.

Furthermore, in the case where the light blocking member2is made of light-reflective material, the light traveling in the sealing member3in a lateral direction is reflected by the inner surface of the recess portion2a(an inner side wall of the light blocking member2), that is, by the light blocking member2, and externally extracted from the upper surface of the sealing member3directly or through the light emitting element1.

Still furthermore, in the case where the light blocking member2is made of a light-absorbing material, the light travelling in the sealing member3in a lateral direction is partially reflected by an interface between the sealing member3and the light blocking member2, and other light is absorbed by the light blocking member2.

Thus, white light is externally extracted from the opening provided on the upper surface of the recess portion2aof the light blocking member2.

When the sealing member3does not contain the fluorescent material, the light emitted from the light emitting element1can be externally extracted from the light emitting device100without being subjected to the wavelength conversion. Alternatively, when the sealing member3contains a large amount of fluorescent material, the light emitted from the light emitting element1can be substantially wholly converted to the light having the different wavelength and externally extracted from the light emitting device100.

The light emitted from the light emitting element1enters not only the sealing member3provided on the upper surface of the light emitting element1, but also enters the sealing member3provided on the outer side surface of the light emitting element1. Therefore, even when a large amount of fluorescent material particles are contained, the sealing member3can be largely provided on the surfaces of the light emitting element1, so that the wavelength of the light can be efficiently converted, and the light can be efficiently externally extracted. Especially, even in the case where an amount of fluorescent materials is increased because several kinds of fluorescent materials are contained, the light emitting device100can be large in light emission amount, that is, it can be high in brightness.

Method of Manufacturing Light Emitting Device

The method of manufacturing the light emitting device100in the first embodiment will be described with reference toFIGS. 3 to 9B.

The method of manufacturing the light emitting device100in this embodiment includes a light emitting element preparing step S101, a mounting substrate preparing step S102, a soluble member forming step S103, a light blocking member forming step S104, a soluble member removing step S105, a light emitting element mounting step S106, a sealing member forming step S107, and a separating step S108.

First, in the light emitting element preparing step S101, the separated light emitting element1having the configuration illustrated inFIG. 2is prepared. Hereinafter, the step of manufacturing the light emitting element1will be described below as one example, but the commercially available light emitting element1may be purchased in the light emitting element preparing step S101.

More specifically, first, the semiconductor laminated body12is formed on the substrate11made of sapphire by sequentially laminating the n-type semiconductor layer12n, the active layer12a, and the p-type semiconductor layer12pwith the above-described semiconductor material. After that, the p-type semiconductor layer12pand the active layer12aare wholly etched away in the one region of the upper surface of the semiconductor laminated body12to form the exposed portion12bin which the n-type semiconductor layer12nis exposed on the upper surface. Furthermore, the substrate11may be removed in a subsequent step.

After that, the light-reflective overall electrode14is formed to cover almost the whole upper surface of the p-type semiconductor layer12p.

Subsequently, the insulating film16is formed of SiO2on a surface of a wafer except for openings16nand16pserving as a connection region between the n-side electrode13and the n-type semiconductor layer12nand a connection region between the p-side electrode15and the overall electrode14, respectively.

Subsequently, the n-side electrode13is formed so as to extend from the opening16nto the upper surface of the insulating film16, and the p-side electrode15is formed so as to extend from the opening16pto the upper surface of the insulating film16.

Thus, the light emitting elements1are formed on the wafer.

After that, a predetermined cut region of the wafer is cut by a dicing method or scribing method, whereby the separated light emitting element1can be prepared.

Before the wafer is cut, the back surface of the substrate11may be thinned by grinding, the substrate11may be removed, or the above-described metal bump or post electrode may be formed.

Then, in the mounting substrate preparing step S102, the mounting substrates4are prepared as illustrated inFIGS. 4A and 4B.FIGS. 4A and 4Billustrate an example in which an aggregated substrate40has a plurality of sequentially formed base members41of the mounting substrates4. In addition, according to this embodiment, the plurality of light emitting devices100are collectively formed on the aggregated substrate40until they are separated in the separating step S108.

According to this embodiment, the plurality of light emitting devices100are collectively manufactured, but the light emitting device100can be manufactured individually.

According to this embodiment, the aggregated substrate40is composed of the six mounting substrates4in a vertical direction and the three mounting substrates4in a horizontal direction which are connected to each other. InFIGS. 4A and 4B, the mounting substrate4corresponding to the one light emitting device100is partitioned by border lines71and border lines72serving as virtual lines. Furthermore, the aggregated substrate40has grooves41aformed along the border lines72and penetrating the base members41in a thickness direction, so that the mounting substrates4are previously separated in the horizontal direction. Furthermore, the wiring electrodes42nand42pare provided as one pair on the one mounting substrate4and each of them extends from the upper surface to the lower surface through the groove41aof the base member41. The wiring electrodes42nand42phave rectangular regions in the center of the upper surface of the base member41as the element mount portions42naand42pawhich are connected to the n-side electrode13and the p-side electrode15of the light emitting element1when the light emitting element1is mounted.

The wiring electrodes42nand42phave regions at both end portions of the base member41in the longitudinal direction as connection regions to an external circuit substrate or the like when the light emitting device100is secondly mounted.

The order of the light emitting element preparing step S101and the mounting substrate preparing step S102may be exchanged, or they may be performed in parallel. Furthermore, the mounting substrate4may be prepared in a separated state, instead of being prepared on the aggregated substrate40. Furthermore, as for the wiring electrodes42nand42pof the mounting substrate4, the regions provided on the upper surface and the lower surface of the base member41may be electrically connected via a through hole penetrating the base member41in the thickness direction of the mounting substrate4. Still furthermore, the wiring electrodes42nand42pof the mounting substrate4may be provided only on the upper surface of the base member41.

Subsequently, in the soluble member forming step S103, as illustrated inFIGS. 5A and 5B, a soluble member5is formed of soluble material which is dissolved in a predetermined solvent, on a region of the upper surface of the mounting substrate4, in which the recess portion2aof the light blocking member2is to be provided.

The soluble member5serves as a mask member to reduce the light-blocking material from being applied to the region for the recess portion2awhen the light blocking member2is formed in the next light blocking member forming step S104. Therefore, the shape of the recess portion2acan be determined by the shape of the soluble member5. For example, when a step is provided in an outer side surface of the soluble member5(an outer side surface of the soluble member5), a step is provided in the inner surface of the recess portion2a. Furthermore, when the outer side surface of the soluble member5is provided as a coarse surface, the inner surface of the recess portion2ais a coarse surface.

The soluble material is dissolved in the predetermined solvent. The predetermined solvent preferably does not dissolve the material used in the light blocking member2. As a detailed description given below, the light blocking member2is preferably made of an epoxy resin or a silicone resin.

For example, the soluble material includes a negative type and a positive type photoresist materials. Among them, the preferably used photoresist material can be dissolved in a solvent which does not damage the above-descried light-blocking material, a plating material of the base material, and a solder resist, in a developing and removing steps. The photoresist can be removed by a mixed solvent of sulfuric acid and hydrogen peroxide, ozone water, an alkalescent solution such as sodium carbonate or organic alkali, a water based solvent such as ozone-containing acetic acid solution, or an organic solvent such as amine series, N-methyl-2-pyrrolidone (NMP), or ethylene carbonate (EC). Among them, in view of the above-described damage to the base material, the photoresist material which can be developed or removed by the organic solvent or alkalescent solution is preferably used.

The solvent for the soluble material includes ketone based solvent such as acetone or methyl ethyl ketone, and water based solvent such as water, warm water, alkaline aqueous solution.

The negative type photoresist material dissolved in the alkalescent solution includes a material mainly containing polyvinyl cinnamate, a material mainly containing a mixture of cyclized rubber and aromatic bisazide, a material mainly containing a mixture of polymethyl isopropenyl ketone and aromatic bisazide, and a mixture of a polyvinyl phenol resin and aromatic diazide. A method of forming the recess portion2awith the negative type photoresist material includes the following methods. That is, the liquid photoresist material is applied on the mounting substrate4by spin coating, or the film photoresist material is attached thereto, so that the photoresist material is widely applied on the mounting substrate4. Then, the region on which the recess portion2aof the light blocking member2is to be formed is irradiated with ultraviolet light such as i line to cure the photoresist material. Then, the other portions are developed with an alkalescent solution and dissolved, and a projected portion is formed of the cured photoresist material in the region for the recess portion2a. Then, the light blocking member2is formed around the projected portion made of the photoresist material and then the photoresist material is dissolved and removed.

The positive type photoresist material dissolved in the alkalescent solution includes a material mainly containing a mixture of an alkali soluble phenol resin and naphthoquinone diazide. The alkali soluble phenol resin includes a cresol novolak resin. When the recess portion2ais formed of the positive photoresist material, for example, the photoresist material is applied on the mounting substrate4by a method similar to the above-described case where the negative type photoresist is used, and then the photoresist material formed on the region for the light blocking member2is irradiated with ultraviolet light such as g line to make the photoresist material soluble on that region. Then, the photoresist material is developed with the alkalescent solution to be dissolved and removed, whereby a projection portion is formed of the photoresist material. Subsequently, the light blocking member2is formed around the projection portion, and then the projection portion made of the photoresist material is dissolved and removed with the alkalescent solution. The positive type photoresist material is preferably used because it becomes soluble in the solvent after the light irradiation, so that when the projection portion is irradiated with the light again before the projection portion is dissolved and removed, the projection portion can be easily dissolved and removed. Furthermore, the positive type photoresist is preferably used because it is not likely to be swollen by a developer, and its sensitivity is steep with respect to the light (that is, contrast is high), so that the shape of the projection portion (that is, the shapes of the recess portion2aand the light blocking member2) can be provided with high precision.

In order to improve the precision of the shapes of the recess portion2aand the light blocking member2, a contrast enhancing agent composed of nitrone or aromatic diazo compound and water soluble polymer material may be used together with the photoresist material.

In addition, the soluble material which is dissolved in the alkaline aqueous solution may be a novolak resin-based or polyhydroxy styrene-based positive type photoresist material which is used in manufacturing the semiconductor.

Other than the above-described materials, the photoresist material may be a polymethyl methacrylate (PMMA) which can be exposed with short-wavelength ultraviolet light.

The soluble material which is dissolved in the ketone based solvent includes (A) an acrylic resin having a functional group which reacts with an epoxy resin at 40° C. to 80° C. of glass-transition point (Tg), (B) an epoxy resin, (C) a phenol resin, and (D) a resin film composed of tetraphenylphosphonium tetra (p-tolyl) borate.

Here, the acrylic resin in (A) has a hydroxyl group as the functional group which reacts with an epoxy resin, the epoxy resin in (B) is at least one selected from the group consisting of a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a novolak type epoxy resin, a biphenyl type epoxy resin, and an aliphatic type epoxy resin, the epoxy resin in (B) is contained by 5 parts to 50 parts by mass with respect to 100 parts by mass of the acrylic resin in (A), the phenol resin in (C) is at least one selected from the group consisting of a terpene phenol resin, a bisphenol A type phenol resin, a bisphenol F type phenol resin, and a novolak type phenol resin, and the phenol resin in (C) is contained by 10 parts to 35 parts by mass with respect to 100 parts by mass of the acrylic resin in (A).

In addition, the soluble material has been disclosed in detail in Japanese Patent No. 4944269, so that a detailed description is omitted here.

The soluble material dissolved in the water or warm water includes polyvinyl alcohol, water-soluble polyester, and oblate (starch).

Thus, the soluble material is used to form the recess portion. On the other hand, in a case where the soluble material is used to form the projection portion (that is, the light blocking member), after the light emitting element has been mounted on the mounting substrate, the soluble material is uniformly provided and patterned appropriately to form the light blocking member with the soluble member, and then a sealing member containing the wavelength conversion substance is formed so as to cover the light emitting element. In this case, an unnecessary soluble member could be left as a residue in the subsequent step in the light emitting device, or the sealing member could be insufficiently cured due to an effect of the unnecessary soluble member.

Meanwhile, according to this embodiment, when the soluble member is used to form the recess portion, it is possible to reduce the residual soluble member and a possibility of the insufficient curing of the sealing member.

For example, the soluble member5can be formed in such a manner that a sheet-shaped soluble material is attached on the upper surface of the mounting substrate4, and formed (patterned) into the predetermined shape with a cutter or dicer.

In addition, instead of attachment of the sheet-shaped soluble member5, the soluble member5may be provided such that a soluble material which has been dissolved or dissolved in a solvent is coated on the upper surface of the mounting substrate4.

Instead, the soluble member5may be previously formed into the shape corresponding to the recess portion2aby cutting a film-shaped soluble material, and attached on the predetermined position on the upper surface of the mounting substrate4. When the soluble member5is made of the photoresist material, it may be patterned by a photolithography method.

In addition, the soluble member5is formed to have a film thickness corresponding to the thickness of the light blocking member2, and the film thickness of the soluble member5may be several μm to 1 mm.

Here, the shape of the patterned soluble member5determines the shape of the recess portion2aof the light blocking member2. Also, in the recess portion2a, the light emitting element1is mounted. Therefore, in the light emitting element mounting step S106to be described below, the recess portion2aneeds to have a size in which the light emitting element1can be mounted in the recess portion2a. In addition, in the case where the sealing member3containing the wavelength conversion substance is formed in the recess portion2a, the recess portion2aneeds to have a size in which a required amount of the sealing member3can be filled to convert the wavelength based on a desired color tone of the emitted light.

Here, the light emitting element1may be previously mounted on the mounting substrate4in the case where there is concern that the subsequent step is adversely affected by the residual soluble member5, or in order to reduce the number of steps. Furthermore, in a case where the light emitting element has a structure in which an electrode having almost the same size and shape as those of the lower surface of the light emitting element is provided on the lower surface of the light emitting element, the soluble member is not likely to be left as the residue on the lower side of the light emitting element1because almost the whole lower surface of the light emitting element1is bonded to the mounting substrate4, which is preferable.

In addition, as for the shape of the recess portion2a, that is, the shape of the soluble member5, in view of mountability of the light emitting element1, it is preferable that each of lengths directionally corresponding to those of the light emitting element1in a planar view (lengths in a vertical and a horizontal directions in the case of a rectangle) is not less than 110% of that of the light emitting element1, and a height is not more than 500% of that of the light emitting element1. Furthermore, as for the shape of the soluble member5, a length ratio with respect to the light emitting element1may vary depending on a corresponding direction in planar view.

Furthermore, as for the shape of the soluble member5, in view of efficiency of the wavelength conversion, it is preferable that a length in planar view is not less than 120% of that of the light emitting element1, and a height is not less than 100% to not more than 500% of that of the light emitting element1.

An upper limit of the length of the soluble member5in planar view is not limited in particular, but the length is preferably not more than 300% of the corresponding length of the light emitting element1to prevent the light emitting device100from becoming too large.

After that, as illustrated inFIGS. 6A and 6B, in the light blocking member forming step S104, the light blocking member2is formed so as to cover the outer side surfaces of the soluble member5. The light blocking member2may be formed of a light-reflective white resin or a light-absorbing black resin by a method such as transfer molding.

Alternatively, after the light blocking member2has been formed up to a height to cover the upper surface of the soluble member5, the upper surface of the light blocking member2may be ground to expose the upper surface of the soluble member5.

The light blocking member2is preferably formed to sequentially cover the outer side surfaces of the plurality of soluble members5in a region in which the plurality of soluble members5are arranged in a row to correspond to the plurality of light emitting devices100as shown inFIG. 6A. According to this embodiment, the light blocking member2is formed continuously for the six soluble members5arranged in the vertical direction. Especially, a thin portion of the light blocking member2such as the side wall of the recess portion2aextending in the horizontal direction in planar view is preferably continuously formed across the border line71. In this case, the thickness at the portion can be increased at the time of resin molding. Thus, the light blocking member2can be appropriately molded even when its resin material is high in light reflectivity but low in fluidity because of containing a large amount of light-reflective substance.

That is, when the amount of the light-reflective substance contained in the resin is increased to increase the light-reflective property of the light blocking member2, the fluidity of the resin could be lowered at the time of molding. In this case, the resin could be insufficiently filled at the time of molding, so that it is sometimes difficult to thinly form the light blocking member2, especially thinly form the side wall of the recess portion2a. However, since the side wall of the recess portion2ais formed after the resin has been sequentially molded and then cut as described above, this portion can be thickly formed compared to a case where this portion is individually formed, so that the light blocking member2can be easily filled.

Furthermore, the light blocking member2may be formed to sequentially cover the three soluble members5arranged in the horizontal direction, or cover all of the soluble members5arranged in the vertical direction and horizontal direction. After the resin molding, an unnecessary light blocking member2formed in a region such as a region along the border line72may be removed by cutting.

According to this embodiment, the light blocking member2is not provided in the right and left end portions of the mounting substrate4, but the light blocking member2may be provided in the right and left portions of the mounting substrate4. In this case, the above-described cutting is not needed after the resin molding.

Then, as illustrated inFIGS. 7A and 7B, in the soluble member removing step S105, the soluble member5is removed with the above-described predetermined solvent. Thus, an inner surface of the light blocking member2is exposed, whereby the recess portion2ais formed in which this inner surface serves as its inner wall. After the soluble member5has been removed, the element mount portions42naand42paof the mounting substrate4are exposed on the bottom surface of the recess portion2a.

After that, as illustrated inFIGS. 8A and 8B, in the light emitting element mounting step S106, the light emitting element1is mounted in the recess portion2aformed on the upper surface of the mounting substrate4. As for a method of mounting the light emitting element1, flip-chip mounting is preferably performed with a solder by a reflow method. According to this embodiment, an appropriate amount of solder paste serving as the bonding member43is applied on the lower surface of the mount surfaces of the n-side electrode13and the p-side electrode15serving as the pad electrodes, and the light emitting element1is mounted in the recess portion2awith the n-side electrode13and the p-side electrode15facing the element mount portions42naand42paof the mounting substrate4, respectively. After that, the solder is dissolved by heat in a reflow furnace, whereby the light emitting element1is bonded to the mounting substrate4through the bonding member43.

In a case where a metal wire is used to connect the light emitting element1to the wiring electrodes42nand42p, or in a case where flip-chip mounting is performed with a bump bonder using ultrasonic vibration, the recess portion2aneeds to have an opening large enough for the insertion of a header portion of a wire bonder or the bump bonder. As for the flip-chip mounting by the reflow method, the opening only needs to be large enough to house the light emitting element1and the solder paste, in the recess portion2a.

After that, as illustrated inFIGS. 9A and 9B, in the sealing member forming step S107, the light transmissive resin material is filled in the recess portion2awith a dispenser61, and then the resin is cured, whereby the sealing member3is formed to seal the light emitting element1. The resin material can include a thermosetting resin.

Furthermore, in the sealing member forming step S107, another coating method such as a spraying method, or screen printing method may be used other than the potting method.

In a case where the resin material to be filled is slurry containing solid particles such as fluorescent material, the potting method is preferably used because the slurry can be dropped and filled in the recess portion2awithout applying very high impact and pressure to the solid particles contained therein. Therefore, even in the case where the resin material to be used contains the above-described fragile solid particles such as KSF florescent material, the sealing member3can be formed without causing serious damage to the solid particles. Furthermore, since the region for the sealing member3is surrounded by the recess portion2a, the sealing member3can be formed with high precision even by the potting method.

According to this embodiment, since the shape of the recess portion2acorresponds to the shape of the soluble member5, it can be formed with high precision. Therefore, compared with a case where the light blocking member2including the shape of the recess portion2ais formed with a die, the recess portion2ahaving the requisite minimum size can be more stably formed. Therefore, the recess portion2acan be decreased in size, and the light blocking member2and accordingly the light emitting device100can be decreased in size.

Since the shape of the recess portion2acan be formed with high precision, the shape of the sealing member3can be also formed with high precision. Therefore, in the case where the sealing member3contains the particles of the wavelength conversion substance, the amount of the wavelength conversion substance can be stably determined, so that it is possible to reduce a variation in color tone of the light emitted from the manufactured light emitting device100.

In order to further decrease the size of the light emitting device, there is a method of manufacturing a light emitting device in which the light emitting element1is flip-chip mounted on the mounting substrate4, the light blocking member2is formed in contact with the outer side surface of the light emitting element, and the sealing member3containing the particles of the wavelength conversion substance is formed in contact with the upper surface of the light emitting element1.

In order to enhance color rendering properties, the sealing member containing particles of several kinds of wavelength conversion substances may be provided. When the several kinds of wavelength conversion substances are used, a total amount of the needed wavelength conversion substances is increased, especially compared with a case where only a YAG-based fluorescent material having high light emission efficiency is used as the wavelength conversion substance. Therefore, when the sealing member containing the wavelength conversion substances is provided only on the upper surface of the light emitting element, the sealing member is increased in thickness, so that its light transmissivity may be degraded, and the light emitting device may be lowered in brightness.

Thus, according to this embodiment, since the sealing member3containing the wavelength conversion substance is provided on the outer side surface in addition to the upper surface of the light emitting element1, so that the thicknesses of the sealing member3can be reduced, so that a large amount of wavelength conversion substance can be used. As a result, even when the large amount of wavelength conversion substance is used, the light emitting device100having high brightness can be manufactured.

As for the slurry to be dropped into the recess portion2a, the resin may be selected to contain particles of the wavelength conversion substance having a specific gravity higher than a specific gravity of the resin. In this case, after the slurry has been dropped, the resin is cured after the particles of the wavelength conversion substance have been precipitated. Thus, the particles of the wavelength conversion substance can be covered with the sufficiently thick resin layer, so that the particles of the wavelength conversion substance can be protected from moisture or gas in the air. Especially, this configuration is preferable when the KSF fluorescent material or quantum dot fluorescent material is used.

After that, in the separating step S108, the aggregated substrate40and the light blocking member2are cut along the border lines71with a dicer, whereby the light emitting device100can be separated. According to this embodiment, since the aggregated substrate40has been already separated by the grooves41aalong the border lines72in the horizontal direction, it is not necessary to cut the aggregated substrate40in the horizontal direction in the separating step S108.

In a case where the groove41ais not provided in the aggregated substrate40, the aggregated substrate40is cut along the border lines72in addition to being cut along the border lines71, whereby the light emitting device100is separated.

Through the above steps, the light emitting device100can be manufactured.

Variations

Next, light emitting devices in the variations of the first embodiment will be described with reference toFIGS. 10A and 10B.

The light emitting device100illustrated inFIG. 1Cis configured such that the inner surface of the recess portion2aof the light blocking member2is substantially perpendicular to the upper surface of the mounting substrate4, but the inner surface of the recess portion2amay be inclined, that is, may be tapered as shown inFIGS. 10A and 10B. In this case, only the inner surface in the horizontal direction or only the inner surface in the vertical direction may be inclined in the recess portion2ain planar view, or an inclined angle may be different between the inner surface in the horizontal direction and the inner surface in the vertical direction.

For example, a light emitting device100A in the variation of the first embodiment illustrated inFIG. 10Aincludes a light blocking member2A having an inclined shape so that an inner surface of a recess portion2Aa becomes wide as it goes upward, instead of the light blocking member2. When the inner surface of the recess portion2Aa is widely inclined as it goes upward, light extraction efficiency can be improved in the light emitting device100A.

When the inner surface of the recess portion2Aa is formed into a reversely tapered shape, the light emitting element1can be easily inserted into the recess portion2Aa when the light emitting element1is mounted.

A light emitting device100B in another variation of the first embodiment illustrated inFIG. 10Bincludes a light blocking member2B having an inclined shape so that an inner surface of a recess portion2Ba becomes narrow as it goes upward, instead of the light blocking member2. When the inner surface of the recess portion2Ba is narrowly inclined as it goes upward, a light distribution is characterized in that directions of the light emitted from the opening of the recess portion2Ba can be upwardly converged. Therefore, the light emitting device100B can be improved in visibility which represents a height of contrast between a light emitting region and a light non-emitting region.

The light emitting devices100A and100B are similar to the light emitting device100except for the shapes of the recess portions2Aa and2Ba, so that their configurations and operations are not described here.

The light emitting devices100A and100B can be manufactured similarly to the light emitting device100except that the soluble member5is formed into the shapes of the recess portions2Aa and2Ba in the soluble member forming step S103, in the method of manufacturing the light emitting device100.

In the soluble member forming step S103, in order to form the tapered inner surface like the recess portion2Aa or2Ba, the outer side surface of the soluble member5is formed into a tapered shape which is thinned or thickened as it goes upward in a direction perpendicular to the upper surface of the mounting substrate4, to follow the inner surface of the recess portion2Aa or2Ba.

In the case where the inner surface is tapered like the recess portion2Aa or2Ba, as for a length in the shape of the recess portion2Aa or2Ba in planar view, a length at an upper end of the opening of the recess portion2Aa or2Ba is preferably set to be equal to a length of the above-described recess portion2aof the light emitting device100.

The outer side surface of the soluble member5can be downwardly or upwardly inclined by obliquely cutting the sheet-shaped soluble member5at a desired angle with a cutter or dicer mechanically when the soluble member5is patterned. Alternatively, after the soluble member5has been formed on the upper surface of the mounting substrate4, the soluble member5may be cut or ground with a dicer or cutter so that the outer side surface can be inclined. Still alternatively, in the case where the photoresist is used as the soluble member5, the photoresist is exposed with an oblique light by use of aberration of a lens to be used in the exposure, exposed with a galvanometer scanner, or exposed with an inclined light source, to form the tapered shape.

As described above, the other steps are similar to those in the method of manufacturing the light emitting device100, so that their description is omitted here.

Second Embodiment

Next, a configuration of a light emitting device in the second embodiment will be described with reference toFIG. 11.

A light emitting device100C in the second embodiment is configured such that the plurality (five) of light emitting elements1are mounted in the recess portion2aof the light blocking member2. Thus, according to the light emitting device100C in the second embodiment, the plurality of light emitting elements1are mounted in the recess portion2aand provided with a mounting substrate4C prepared for the plurality of light emitting elements1, instead of the mounting substrate4. Other configurations of the light emitting device100C are similar to those of the light emitting device100, so that a detailed description is omitted.

The light emitting device100C has a shape suitable for being used as a linear light source in which the plurality of light emitting elements1are linearly disposed in a row.

The light emitting device100C includes the five light emitting elements1, and the mounting substrate4C which is long enough to mount the five light emitting elements1linearly arranged in a row in a longitudinal direction. The mounting substrate4C has four relay wiring electrodes42a, in addition to the wiring electrodes42nand42pfor external connection. The four wiring electrodes42aare disposed in a row to be spaced apart from each other on the upper surface of the base member41between the wiring electrodes42nand42pin the longitudinal direction. The one light emitting element1is disposed with respect to each adjacently disposed pair of wiring electrodes42n,42a, and42p. Therefore, the five light emitting elements1are electrically connected in series through the relay wiring electrodes42a. Furthermore, the light blocking member2provided on the upper surface of the mounting substrate4C has the recess portion2alarge enough to house the five light emitting elements1disposed in a row. The sealing member3is provided in the recess portion2ato seal the light emitting elements1.

As for the size of the recess portion2ain this embodiment, that is, the shape of the soluble member5forming in the manufacturing process, a gap between the light emitting element1disposed at the end and an inner surface of the recess portion2amay be set equally to a gap between the inner surface of the recess portion2aand the light emitting element1described in the first embodiment.

The shape of the light emitting element1in planar view is not only a rectangle but also another polygonal shape such as square shape, circular shape, or elliptical shape. Furthermore, the number of the light emitting elements1mounted in the one recess portion2acan be suitably selected, and their layout manner may be such that they are arranged in a short-side direction or two-dimensionally arranged. Still furthermore, the plurality of mounted light emitting elements1may be connected in parallel, or both in series and in parallel, instead of only being connected in series.

The shape of the recess portion2amay have an inclined inner surface like the variations in the first embodiment.

The light emitting device100C can be operated similarly to the light emitting device100except that a power is supplied to the plurality of light emitting elements1through the wiring electrodes42n,42p, and42aon the mounting substrate4C, so that its operation is not described in detail here.

The light emitting device100C can be similarly manufactured by the method of manufacturing the light emitting device100in the first embodiment except that the mounting substrate4C is prepared in the mounting substrate preparing step S102to have the shape to mount the plurality of light emitting elements1and include the wiring electrodes42n,42p, and42a, and the plurality of light emitting elements1are mounted in the light emitting element mounting step S106, so that a detailed description of its manufacturing method is not given here.

In the above, the method of manufacturing the light emitting device in this disclosure has been specifically described by way of the embodiment, but the scope of the present invention is not limited to the above description and should be widely interpreted based on claims. Furthermore, various modifications and variations made based on the above description are included in the scope of the present invention as a matter of course.