JPH10233533A - Method and device for forming light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to accurately control the content and distribution of a fluorescent material on an LED chip by applying a desired amount of a mixture of the fluorescent material and a binder to the LED chip while the mixture is held while stirring so that the concentrations of the fluorescent material and binder in the mixture may become constant. SOLUTION: An injecting device 101 has a holding means which holds a fluorescent material and a binder which is made to contain the fluorescent material and the holding means is provided with a stirring means which mixes the fluorescent material and binder together and stirs the mixture so that the concentrations of the material and binder in the mixture may become constant. Then the mixture containing prescribed amounts of the fluorescent material and binder is applied to an LED chip by adjusting the position of a substrate 103 on which the LED chip is arranged to an injection hole from the device 101 by means of a position adjusting means 102. Therefore, a light emitting device having a stable light emitting characteristic can be formed with high volume productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a fluorescent material
The present invention relates to a method and apparatus for forming a light-emitting device that converts at least a part of light from an ED chip into a wavelength, and particularly relates to a method for forming a light-emitting device having a high yield with less variation in light emission characteristics and uneven light emission characteristics between formed light-emitting devices. The present invention relates to a forming apparatus.

[0002]

2. Description of the Related Art A light-emitting device (hereinafter also referred to as a light-emitting diode) emits light of a small size with good efficiency and vivid colors. In addition, since it is a semiconductor element, there is no fear of breaking the ball. It has excellent initial drive characteristics and is resistant to vibration and ON / OFF lighting. Therefore, it is used as various indicators and various light sources. Such a light emitting device has an excellent monochromatic peak wavelength, and can emit various emission wavelengths from ultraviolet to infrared depending on the semiconductor material of the light emitting layer used, forming conditions, and the like. However, since the LED chip constituting the light emitting device has an excellent monochromatic peak wavelength, it is necessary to use mixed color light to emit white light or the like. An LED chip capable of emitting blue light and a light emitting diode capable of converting a part of light from the LED chip such as a light emitting diode capable of emitting mixed color light or the like capable of emitting white light in combination with a fluorescent substance capable of emitting yellow light Can be considered.

More specifically, as shown in FIG. 3, an LED chip using InGaN, which is a nitride-based compound semiconductor having a large band gap and capable of emitting a relatively short wavelength, is used for the light emitting layer. On the other hand, a yttrium-aluminum-garnet-based phosphor is used as a phosphor that converts a part of the light emitted from the light emitting layer of the nitride-based compound semiconductor to another wavelength. The yttrium / aluminum / garnet-based phosphor has high light resistance, and can emit white light by mixing blue light from the LED chip and yellow light from the fluorescent substance.

[0004] Such an LED chip having a large energy band gap of the light emitting layer is arranged on a cup provided at the tip of a lead frame. LED chip is L
Each of them is electrically connected to a metal stem or a metal post provided with an ED chip. A light-emitting device can be formed by disposing a yttrium-aluminum-garnet-based fluorescent substance that absorbs light from an LED chip and converts the wavelength, on the LED chip.

[0005] In order to emit a desired white light or the like using such a light emitting device, it is necessary to emit each light with extremely high accuracy and to perform color mixing adjustment. Light from the LED chip can be adjusted relatively easily by its semiconductor, drive current, and the like. On the other hand, the wavelength-converted light from the fluorescent substance can also be adjusted to some extent by controlling the composition and particle size of the fluorescent substance.

[0006]

However, since the fluorescent substance itself has no adhesive force, in order to arrange and fix it on the LED chip, it is possible to emit light of the LED chip and the fluorescent substance, such as in various resins or glass. It must be contained in a binder having adhesiveness. Regarding the fluorescent substance contained in such a binder, the amount of light emitted from the LED chip and the amount of light emitted from the fluorescent substance largely depend on the content and distribution of the fluorescent substance. If these cannot be controlled, and the light emitted from the LED chip and the light emitted from the fluorescent substance are visible light, and the colors are expressed by their respective colors, the difference in the amount of light poses a particularly serious problem. SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a method for forming a high-yield light-emitting device which can control the content and distribution of a fluorescent substance with extremely high accuracy and has excellent light-emitting characteristics.

[0007]

SUMMARY OF THE INVENTION The present invention is a method for forming a light emitting device comprising: an LED chip; and a fluorescent substance that absorbs at least a part of light emitted from the LED chip and converts the wavelength to emit light. A step of maintaining the density of the fluorescent substance in the binder while stirring so as to be substantially constant, and a step of coating a desired amount on the LED chip while maintaining the density of the mixture of the fluorescent substance and the binder. A method of forming a light emitting device having a constant temperature of the binder in the step of holding while stirring. Further, it is a method for forming a light emitting device in which the stirring is performed in a non-contact manner from a driving unit.

Further, there is provided an apparatus for forming a light emitting device having an LED chip and a fluorescent substance which absorbs at least a part of light emitted from the LED chip and converts the wavelength to emit light, wherein a binder containing the fluorescent substance is provided. Device having a holding means for holding the mixture while stirring, a discharging means for discharging the mixture of the fluorescent substance and the binder from the holding means while maintaining the density, and an LE disposed on the substrate.
It is a light emitting device forming device having a position control means for aligning the discharging means of the injection device on the D chip, and also a light emitting device forming device having heating and / or cooling means for keeping the temperature of the holding means constant. .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of various experiments, the present inventor has found that a method of forming a light-emitting device in which at least a part of light emitted from an LED chip is changed in wavelength by a fluorescent substance, a binder containing a fluorescent substance is included. It has been found that a light emitting device having excellent light emitting characteristics and a high yield can be formed by applying an agitated and held material.

That is, the light emission characteristics are greatly affected by the viscosity of the binder and the degree of sedimentation of the fluorescent substance. This is one of the causes of a case where the light from the LED chip is strong or a case where the light from the fluorescent substance is strong for each light emitting device. In an extreme case, it is observed that only blue light emitted from the LED chip emits light. Alternatively, only yellow light from the fluorescent substance may be observed. In addition, color unevenness may be observed for each light emitting device due to variations in the fluorescent material.

Specifically, the binder containing the fluorescent substance is optically connected by coating or the like while maintaining fluidity using an injecting device such as a syringe having a long and narrow hole. Placed on the LED chip. If the viscosity of the binder is high, the distribution of the fluorescent substance can be easily controlled, but the injection (discharge) pressure increases and the mass productivity decreases. On the other hand, when the viscosity decreases, the content of the fluorescent substance contained in the binder having a specific gravity smaller than that of the fluorescent substance and the gradient of the density of the fluorescent substance in the coating portion vary. The present invention makes it possible to form a light-emitting device having excellent light-emitting characteristics by reducing the change in density that occurs during the process of holding a binder containing a fluorescent substance while increasing mass productivity by stirring.

FIG. 4 shows a chip type LED as an example of a method for forming a light emitting device. An LED chip 402 using a gallium nitride-based semiconductor is fixed by die bonding using an epoxy resin or the like in a housing of a chip type LED. A gold wire 403 as a conductive wire is electrically connected to each electrode of the LED chip and each electrode provided on the housing.

In this state, a binder containing a fluorescent substance was applied as a coating part 401. As an yttrium / aluminum / garnet-based fluorescent material activated with cerium, Y ₃ Al ₅ O ₁₂ : Ce mixed and dispersed in an epoxy resin was used. The amount of fluorescent material applied is
Since an extremely small amount of about 0.01 ml is sufficient, a binder containing a fluorescent substance is applied by an injection device 101 such as a syringe. At this time, the injection device holds the epoxy resin containing the fluorescent substance inside, and the stirring screw 20.
1 is arranged. The stirring screw 201 is rotated so that the density of the fluorescent substance emitted from the injection device becomes equal. A binder containing a fluorescent substance having substantially the same density of the fluorescent substance is extruded from the tip of the injection device by air, N _2, or argon gas sent from the compressor through the tube 204. The extruded phosphor-containing binder is heat-cured to uniformly cure and form a coating part for color conversion by converting the LED chip, a conductive wire, and the like into a mold member for protecting the conductive wire from external stress and the like. By supplying power to such a light emitting device, the LED chip emits light. By mixing light emitted from the LED chip with light emitted from a fluorescent substance excited by the light emission, a light emitting device capable of emitting a white light with very little color unevenness and excellent in mass productivity can be formed. Hereinafter, the components of the present invention will be described in detail.

(Injection device 101) Injection device 1 of the present invention
01 means that the binder containing the fluorescent substance can be discharged at a constant rate. In particular, with light from LED chips,
In the case of mixed color emission with a fluorescent substance that emits light while being excited by this light, even if the injection amount is extremely small, the emission color greatly fluctuates. Therefore, the fluorescent substance and the binder containing the fluorescent substance are emitted from the pores 203 such as an injection needle. The diameter of the pores depends on the particle size and shape of the fluorescent substance, the material and viscosity of the binder, etc., but is about 10 μm to 3 m.
m is more preferably 50 μm to 200 μm
It is. Also, in order to discharge the fluorescent substance and the binder from the injection device, air for controlling the minute amount,
It is more preferable to control the discharge by applying pressure with a gas such as N ₂ or an inert gas which does not adversely affect the light emitting device. When the gas is transferred through the pores as described above, the fluorescent substance contained in the binder is easily discharged while keeping the density of the fluorescent substance constant. The closed pores are particularly preferably used in the present invention, because the pores can be discharged while maintaining the density of the fluorescent substance more constant.

The injection device 101 has a holding means for holding a fluorescent substance and a binder for containing the fluorescent substance. The holding means has a stirring means 201 for mixing and stirring such that these densities are constant. Stirring means 201
May be rotated and agitated by directly connecting a member such as a screw to a motor or the like.
There is also a method of rotating and stirring in a non-contact manner with a driving means such as a motor utilizing the method 2 above. Such stirring can be performed variously, such as continuously or intermittently, as long as the density of the fluorescent substance contained in the binder does not change. The number of rotations of the stirring can be selected variously depending on the size of the stirring section, the particle size and shape of the fluorescent substance, the viscosity and the material of the binder, and is preferably 3 to 100 times / minute. In addition, the stirring unit can take various shapes such as a screw shape and a plate shape as long as the binder containing the fluorescent substance can be stirred.

(Heating and / or cooling means 205) The heating and cooling means 205 is for keeping the temperature in the holding means of the injection device 101 constant. Such heating and / or cooling means can be made constant using various methods such as lamp heating, resistance heating, and cooling using a heat pump. Thereby, the temperature of the binder containing the fluorescent substance can be kept constant to control the viscosity and also improve the mass productivity. Therefore, since the sedimentation speed of the fluorescent substance in the binder can be adjusted, the density by stirring can be made more constant. Such a constant temperature device as a heating and / or cooling means is particularly effective when an epoxy resin is used as a binder.

(Position Adjusting Means 102) The position adjusting means 102 used in the present invention adjusts the positions of the substrate 103 on which the LED chips are arranged and the injection hole from the injection device 101, so that the positions on the LED chips are adjusted. In order to dispose a fluorescent substance and a binder containing the fluorescent substance at a desired position. For such alignment, for example, the position of the LED chip and the position of the injection unit of the injection device are respectively detected by various optical sensors and the like, and the injection unit and / or the LED chip can be variously moved on an XY stage. Positioning can be performed by using an appropriate driving unit.

(Fluorescent substance) Fluorescent substance used in the present invention
Excited by electromagnetic waves emitted from the semiconductor light emitting layer
A fluorescent substance that emits light when it is emitted. As a fluorescent substance,
Yttrium aluminum gar activated with lium
Net-based phosphors, perylene-based derivatives, copper-activated cells
And zinc lenide. In particular,
It is an aluminum-garnet phosphor (RexSm
1-x)_Three(AlyGa1-y)_FiveO ₁₂: Ce (however, R
e is at least one selected from Y, Gd and La)
Uses gallium nitride compound semiconductor for LED chip
Is particularly preferable from the viewpoint of light resistance and efficiency.

The yttrium-aluminate-garnet-based phosphor activated with cerium has a garnet structure and is resistant to heat, light and moisture, and can have an excitation spectrum peak near 450 nm. Further, the emission peak is around 530 nm and has a broad emission spectrum with a tail extending to 700 nm. In addition, the emission wavelength shifts to a short wavelength by substituting a part of the Al in the composition with Ga, and the emission wavelength shifts to a long wavelength by substituting a part of the Y in the composition with Gd. By changing the composition in this way, the emission color can be continuously adjusted. That is, there is an ideal condition for converting blue light emission of the nitride semiconductor into white light emission such that the intensity on the long wavelength side can be continuously changed by the composition ratio of Gd. Similarly, Lu, Lc,
Desired characteristics may be obtained by adding Sc or Sm.

Therefore, when the yttrium-aluminum-garnet-based phosphor activated with cerium is used, it is particularly arranged in contact with or close to the LED chip, and the irradiance is (Ee) = 3 W · cm ⁻² or more. 10W
A light emitting device having sufficient light resistance can be obtained with high efficiency even at cm ⁻² or less.

Such fluorescent materials include Y, Gd, Ce,
An oxide or a compound which easily becomes an oxide at a high temperature is used as a raw material of Sm, La, Al and Ga, and these are sufficiently mixed in a stoichiometric ratio to obtain a raw material. Or Y, Gd,
A co-precipitated oxide obtained by co-precipitating a solution obtained by dissolving a rare earth element of Ce, Sm, La in an acid at a stoichiometric ratio with oxalic acid, and aluminum oxide and gallium oxide are mixed and mixed. Get the raw materials. An appropriate amount of a fluoride such as ammonium fluoride is mixed into the crucible as a flux, and the mixture is baked in air at a temperature range of 1350 to 1450 ° C for 2 to 5 hours to obtain a baked product. It can be obtained by ball milling, washing, separating, drying and finally passing through a sieve.

LE using gallium nitride-based compound semiconductor
When the light emitted from the D chip and the light emitted from the fluorescent substance with the body color being yellow have a complementary color relationship,
When light emission from the LED chip and light emission from the fluorescent substance are mixed and displayed, white light emission color display can be performed. By variously adjusting the ratio of the fluorescent substance to the resin, the application and the filling amount, and selecting the emission wavelength of the light emitting element, it is possible to provide an arbitrary color tone such as a light bulb color including white.

In the light emitting device of the present invention, such a fluorescent substance may be a mixture of two or more fluorescent substances.
Specifically, two or more kinds of yttrium / aluminum / garnet-based phosphors having different contents of Al, Ga, Y, Gd, La and Sm can be mixed to increase the RGB wavelength component.

(LED Chips 302 and 402) The LED chips 302 and 402 used in the present invention are semiconductor light-emitting elements having a light-emitting layer capable of emitting a light emission wavelength capable of exciting a fluorescent substance. Preferable examples of such a semiconductor light emitting device include a nitride-based compound semiconductor capable of emitting a short wavelength light capable of efficiently exciting a fluorescent substance.
Semiconductor structures include MIS junction, PIN junction, and PN
Examples thereof include those having a homo structure, a hetero structure, and a double hetero structure having a junction or the like. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal thereof.
Also, a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed as a thin film in which a quantum effect occurs can be used.

When a gallium nitride compound semiconductor is used, sapphire, spinel, SiC, S
Materials such as i and ZnO are preferably used. In order to form gallium nitride having good crystallinity, a sapphire substrate is preferably used. MOCV on this sapphire substrate
A nitride-based compound semiconductor can be formed by the method D or the like. GaN, AlN, In on sapphire substrate
A buffer layer of N or the like is formed, and a gallium nitride semiconductor having a PN junction is formed thereon. Gallium nitride-based semiconductors exhibit N-type conductivity without being doped with impurities.
When a desired N-type gallium nitride semiconductor is formed, for example, to improve luminous efficiency, Si, G
It is preferable to appropriately introduce e, Se, Te, C, and the like.
On the other hand, when forming a P-type gallium nitride semiconductor, P
Type dopants Zn, Mg, Be, Ca, Sr, B
a and the like are doped. Gallium nitride based compound semiconductors
Since it is difficult to form a P-type by simply doping with a P-type dopant, it is preferable to form the P-type by annealing with heating in a furnace, low-speed electron beam irradiation, plasma irradiation, or the like after the introduction of the P-type dopant. After the exposed surfaces of the P-type semiconductor and the N-type semiconductor are formed by etching or the like, each electrode having a desired shape is formed on the semiconductor layer by a sputtering method, a vacuum evaporation method, or the like.

Next, the formed semiconductor wafer or the like is directly full-cut by a dicing saw in which a blade having a diamond blade is rotated, or after a groove having a width wider than the blade width is cut (half cut). The semiconductor wafer is broken by external force. Alternatively, an extremely thin scribe line (meridian) is drawn on the semiconductor wafer, for example, in a checkerboard pattern by a scriber in which a diamond needle at the tip reciprocates linearly, and then the wafer is cut by an external force and cut into chips from the semiconductor wafer. Thus, an LED chip that is a gallium nitride-based compound semiconductor can be formed.

In the case where white light is emitted in the light emitting device of the present invention, the emission wavelength of the light emitting element is preferably 400 nm or more and 530 nm or less, and 420 nm or more in consideration of the complementary color relationship with the light emitted from the fluorescent substance, resin deterioration, and the like. 490n
m or less is more preferable. In order to further improve the excitation and luminous efficiencies of the LED chip and the fluorescent substance, respectively, 45
It is more preferably from 0 nm to 475 nm.

(Conductive Wires 303, 403) The conductive wires 303, 403 are required to have good ohmic properties, mechanical connectivity, electrical conductivity, and thermal conductivity with the electrodes of the LED chip. 0.0 as thermal conductivity
Preferably 1cal / cm ² / cm / ℃ or, more preferably 0.5cal / cm ² / cm / ℃ above. In addition, the diameter of the conductive wire is preferably Φ10 μm or more and Φ45 μm or less in consideration of workability and the like. Specific examples of such a conductive wire include a conductive wire using a metal such as gold, copper, platinum, and aluminum, and an alloy thereof. Such a conductive wire can easily connect an electrode of each LED chip to an inner lead, a mount lead, and the like by a wire bonding device.

(Mount Lead 305) As the mount lead 305, the LED chip 302 is arranged, and it is sufficient that the mount lead 305 is large enough to be mounted on a die bonding device or the like. Further, when a plurality of LED chips are provided and the mount leads are used as a common electrode of the LED chips, sufficient electric conductivity and connectivity with a bonding wire or the like are required. In addition,
In the case where the LED chip is arranged in the cup on the lead and the fluorescent material is filled therein, it is possible to prevent false lighting by light from another light emitting device arranged in the vicinity.

The bonding between the LED chip and the cup of the mount lead can be performed by a thermosetting resin or the like. Specific examples include an epoxy resin, an acrylic resin, an imide resin, a phenol resin, and a silicone resin. Metal oxides such as SnO ₂ , ITO, ZnO, Ag
Alternatively, a resin paste containing carbon or the like, a metal bump, or the like may be used. further,
In order to improve the light use efficiency of the light emitting device, the surface of the mount lead on which the LED chip is disposed may be mirror-like, and the surface may have a reflection function. In this case, the surface roughness is preferably 0.1S or more and 0.8S or less. The specific electrical resistance of the mount lead is 300 μΩ
cm or less, more preferably 3 μΩ · cm or less. Also, when a plurality of LED chips are mounted on the mount leads, good heat conductivity is required because the amount of heat generated from the LED chips increases. ^{Specifically, 0.01cal / cm 2 / cm /} ℃ or more preferably preferably 0.5cal / cm ² / cm / ℃ above. Materials satisfying these conditions include iron, copper, copper with iron, copper with tin, and ceramics with metallized patterns.

(Inner Lead 306) The inner lead 306 is used to connect the conductive wire 303 connected to the LED chip 302 disposed on the mount lead 305. In the case where a plurality of LED chips are provided on the mount lead, it is necessary to arrange the conductive wires so that the conductive wires do not contact each other. Specifically, as the distance from the mount lead increases, the area of the end face of the inner lead to which wire bonding is performed can be increased to prevent contact of the conductive wire connected to the inner lead further away from the mount lead. it can. In addition,
The contact of the conductive wire can also be prevented by increasing the height of the inner lead as the distance from the lead increases. The roughness of the connection end face with the conductive wire is preferably 1.6S or more and 10S or less in consideration of adhesion. The inner leads are required to have good connectivity and electrical conductivity with a conductive wire such as a bonding wire. As a specific electric resistance, 300 μ
Ω · cm or less, more preferably 3 μΩ · cm
It is as follows. Materials that meet these requirements include iron,
Copper, iron-containing copper, tin-containing copper and copper, gold, silver-plated aluminum, iron, copper and the like.

(Coating Portion 301) The coating portion 301 is obtained by curing a binder containing a fluorescent substance, and is provided on a cup of a mount lead separately from a mold member. As a specific material of the coating portion, a translucent resin having excellent weather resistance, such as an epoxy resin, a urea resin, or a silicone resin, or glass is preferably used. The coating member may contain a diffusing agent together with the fluorescent substance. As a specific diffusing agent, barium titanate, titanium oxide, aluminum oxide, silicon oxide, or the like is suitably used. Similarly, a light stabilizer and a colorant can be contained together with the fluorescent substance. Preferable examples of the light stabilizer include a benzohindered amine-based light stabilizer, a lyazole-based ultraviolet absorber, and a benzophenone-based ultraviolet absorber.

(Mold member 304) Mold member 30
4 can be provided to protect the LED chip, the conductive wire, the coating portion containing the fluorescent substance, and the like from the outside according to the use application of the light emitting device. The mold member can be formed using various resins and glass. The viewing angle can be increased by including a fluorescent substance. However, by including a diffusing agent in the mold member, the directivity from the LED chip can be reduced and the viewing angle can be further increased. Furthermore,
By forming the mold member into a desired shape, it is possible to have a lens effect of converging or diffusing light emitted from the LED chip. Therefore, a structure in which a plurality of mold members are stacked may be employed. Specifically, a convex lens shape, a concave lens shape, an elliptical shape as viewed from the light emission observation surface, a combination of a plurality of them, and the like are exemplified.

As a specific material of the mold member 104, a translucent resin having excellent weather resistance, such as an epoxy resin, a urea resin, or a silicone resin, or glass is preferably used. As the diffusing agent, barium titanate, titanium oxide, aluminum oxide, silicon oxide and the like are preferably used. Further, in addition to the diffusing agent, a fluorescent substance can be contained in the mold member. Therefore,
The fluorescent substance may be contained in the mold member, or may be contained in other coating portions or the like. Alternatively, the coating portion may be formed using a different material such as a resin containing a fluorescent substance and the mold member using glass or the like. In this case, a light emitting device with high productivity and less influence of moisture or the like can be obtained. Further, the mold member and the coating portion may be formed using the same member in consideration of the refractive index. Further, similarly to the coating portion, a light stabilizer and various colorants such as organic and inorganic may be contained. Hereinafter, embodiments of the present invention will be described, but it goes without saying that the present invention is not limited to only specific embodiments.

[0035]

【Example】

(Example 1) In an LED chip, an In _0.2 Ga _0.8 N semiconductor having a light emission peak of 450 nm was used as a light emitting layer. LE
The D-chip is to flow a TMG (trimethyl gallium) gas, a TMI (trimethyl indium) gas, a nitrogen gas and a dopant gas together with a carrier gas on a cleaned sapphire substrate, and to form a nitride-based compound semiconductor by MOCVD. Formed. By switching between SiH ₄ and Cp ₂ Mg as the dopant gas, N
A semiconductor having a mold or P-type conductivity is formed. As the light emitting element, a contact layer made of a gallium nitride semiconductor having N-type conductivity, a cladding layer made of an aluminum gallium nitride semiconductor having P-type conductivity, and a contact layer made of gallium nitride having P-type conductivity were formed. . An InGaN active layer having a thickness of about 3 nm and a single quantum structure is formed between the N-type contact layer and the P-type cladding layer.
(Note that a gallium nitride semiconductor is formed on the sapphire substrate at a low temperature to serve as a buffer layer. The P-type semiconductor is annealed at 400 ° C. or higher after film formation.)

PN on sapphire substrate by etching
After exposing the surface of each semiconductor contact layer, each electrode was formed by sputtering. After the scribe line was drawn on the semiconductor wafer thus completed, it was divided by an external force to form LED chips.

On the other hand, an iron-containing copper lead frame is formed by punching and stamping, which is connected by a tie bar and has a cup formed at the tip of a mount lead. Using an epoxy resin, the LED chip was die-bonded into the tip cup of a copper lead frame containing iron, which was silver-plated with a die bonding device. Each electrode of the LED chip was wire-bonded to a mount lead or an inner lead provided with a cup with a gold wire to establish electrical continuity.

As a fluorescent substance, a solution obtained by dissolving rare earth elements of Y, Gd and Ce in an stoichiometric ratio in an acid was coprecipitated with oxalic acid. This is mixed with a coprecipitated oxide obtained by calcination and aluminum oxide to obtain a mixed raw material. This was mixed with ammonium fluoride as a flux, packed in a crucible, and fired in air at a temperature of 1400 ° C. for 3 hours to obtain a fired product. The calcined product was ball milled in water, washed, separated, dried, and finally formed through a sieve.

(Y _0.8 Gd _0.2 ) ₃ Al ₅ O _{12 formed} :
75 parts by weight of the Ce fluorescent material and 100 parts by weight of the elastomeric silicone resin were mixed well to form a slurry. This slurry was placed in the holding means of the injection device shown in FIGS. The holding means has a built-in stirring screw, and a part of the stirring screw is formed by a magnet. The stirring screw rotates 30 times / minute continuously without contact with a magnet arranged outside the holding means. The holding means is connected to an air conditioner press, and the slurry is discharged from the injection hole by pressure. When a predetermined amount of slurry is discharged into the cup of one of the mounting leads positioned in advance, the air pressure is reduced and the injection hole is moved. Next, 0.2 μl of a binder, which was sequentially coated in another cup and contained a fluorescent substance, was injected onto the LED chip. (The holding means is externally heated by a lamp.) After the injection, the resin containing the fluorescent substance was cured at 150 ° C. for 1 hour.

Thus, the LED chip having a thickness of 120 μm
The coating part containing the fluorescent substance was formed.
Thereafter, a translucent epoxy resin was formed as a mold member for the purpose of further protecting the LED chip and the fluorescent substance from external stress, moisture, dust and the like. The mold member is inserted into a shell frame of a lead frame on which a coating is formed, mixed with a translucent epoxy resin, and then heated to 150 ° C.
Cured in 5 hours. After cutting the tie bar to which each lead is connected, a light emitting device can be obtained. 500 such light emitting devices were formed and the variation was measured. The chromaticity point of the light emitting device capable of emitting white light was measured and plotted on CIE coordinates. In addition, it was confirmed that there was no uneven light emission in appearance in each light emitting device.

(Comparative Example 1) A light emitting device capable of emitting white light was formed in the same manner as in Example 1 except that the stirring step was not performed on the holding means, and the variation was measured in the same manner as in Example 1. The chromaticity point of the light emitting device capable of emitting white light was measured and plotted on CIE coordinates. The comparative example was compared with the area connecting the chromaticity points of the outermost shell of Example 1 as 1.
The light emitting device of Comparative Example 1 which is six times as large as that of Example 1 and clearly formed was superior to the present invention. Further, in some of the light emitting devices, those having uneven light emission were confirmed.

[0042]

According to the method and the apparatus for forming a light emitting device having a fluorescent substance according to the present invention, a light emitting device having stable light emitting characteristics can be formed with high mass productivity.

In particular, according to the forming method of the first aspect,
A light emitting device formed first even during mass production for a long time,
Variations in light emission characteristics of a light emitting device formed later can be made extremely small. In addition, since uneven light emission can be reduced without a light emitting device formed relatively easily, mass productivity and yield can be improved.

Further, according to the forming method of the second aspect, it is possible to form a light-emitting device having excellent light-emitting characteristics with improved mass productivity and yield.

According to the third aspect of the present invention, it is possible to more easily form a light emitting device having improved mass productivity and yield.

According to the fourth aspect of the present invention, it is possible to form a light emitting device with good mass productivity and excellent light emitting characteristics.

According to the fifth aspect of the present invention, it is possible to form a light-emitting device having improved light-emitting characteristics with improved mass productivity and yield.

[0048]

[Brief description of the drawings]

FIG. 1 is a schematic view of a forming apparatus of the present invention for forming a light emitting device.

FIG. 2 is a schematic sectional view of an injection device used in the present invention.

FIG. 3 is a schematic sectional view of a light emitting device formed according to the present invention.

FIG. 4 is a schematic cross-sectional view of another light emitting device formed according to the present invention.

[Explanation of symbols]

101 ... Injection device 102 ... Position control means 103 ... Lead terminal connected with a tie bar and on which an LED chip is arranged 201 ... Stirring means 202 for stirring the binder and fluorescent substance held inside 202 ... Magnet for rotating the stirring means from the driving means in a non-contact manner 203 ... Needle section having pores for discharging binder and fluorescent substance 204 ... Tube connected to air compressor etc.

Claims (5)

[Claims] 1. A method for forming a light emitting device, comprising: an LED chip; and a fluorescent substance that absorbs at least a part of light emitted from the LED chip and emits light by wavelength conversion, wherein the density of the fluorescent substance in a binder is provided. And a step of maintaining the density of the mixture of the fluorescent substance and the binder while maintaining the density of the mixture with the fluorescent substance and the binder.
And a step of applying a desired amount on the chip. 2. The method for forming a light emitting device according to claim 1, wherein the temperature of the binder is kept constant in the step of holding while stirring. 3. The method for forming a light emitting device according to claim 1, wherein said stirring is performed without contact from a driving means. 4. An apparatus for forming a light emitting device, comprising: an LED chip; and a fluorescent substance that absorbs at least a part of light emitted from the LED chip and converts the wavelength to emit light, wherein the binder contains the fluorescent substance. Device having holding means for holding the mixture while stirring, and discharging means for discharging while maintaining the density of the mixture of the fluorescent substance and the binder from the holding means; and a filling device on the LED chip arranged on the base. And a position control means for adjusting the discharge means. 5. An apparatus for forming a light emitting device according to claim 4, further comprising heating and / or cooling means for keeping the temperature of said holding means constant.