KR100632715B1 - Light emitting diode with pastel color of orange, yellow and green and method of manufacturing the same - Google Patents

Abstract

An orange, yellow or green pastel color LED device comprising a blue or cyan LED chip and an Sr _{1- x} S _x : Eu phosphor (where x is 0.3 to 0.7) is disclosed. Pastel color LED device according to an embodiment of the present invention is evenly dispersed in the member for mounting the LED chip, the LED chip for emitting blue or cyan light, the mold resin encapsulating the LED chip and the resin for the mold And Sr _{1- x} S _x : Eu phosphor for fluorescence conversion of light emitted from LED chip. The LED device according to the present invention combines the light emitted from the LED chip with the red-based light fluorescence-changed by the phosphor and emits orange, yellow or green pastel color light.

Light Emitting Diode, Pastel Color, Phosphor, CIE Chromaticity Diagram

Description

Light emitting diode with pastel color of orange, yellow and green and method of manufacturing the same

Figure 1a is a schematic cross-sectional view showing a lamp-type pastel color LED device according to an embodiment of the present invention.

Figure 1b is a schematic cross-sectional view showing a chip-like pastel color LED device according to another embodiment of the present invention.

Figure 1c is a schematic cross-sectional view showing a top pastel color LED device according to another embodiment of the present invention.

2 is Sr _{1- x} S _x: in accordance with an embodiment of the present invention containing 3% by weight of Eu phosphor, a 5% by weight and 7 weight%: Eu which does not include the LED element and the phosphor Sr _{1- x} S _x This graph shows the light spectrum of pastel color LED devices.

FIG. 3 is a view showing coordinate positions on a CIE chromaticity diagram of the LED elements shown in FIG. 2.

FIG. 4 is a graph illustrating measurements of luminance of the LED devices illustrated in FIG. 2.

Figure 5 is a graph showing the thermal budget over time in the method of manufacturing a pastel color LED device according to an embodiment of the present invention.

The present invention relates to a pastel color light emitting diode device (LED device), and more particularly to an LED device for emitting pastel color light of orange, yellow or green (hereinafter referred to as 'orange color'); It relates to a manufacturing method thereof.

'Pastel color LED device' generally refers to an LED device that emits pastel-colored flexible neutral colors instead of blue, green or red primary colors. That is, the pastel color LED device emits light of the intermediate color located in the region adjacent to the white region, not the light in the vicinity of the line connecting red, blue, and green in the CIE chromaticity diagram. The emitted light of such pastel color LED devices is generally represented by a light spectrum having two or more peak wavelengths. Therefore, in the present specification, the term “green pastel color LED device” is not a primary LED device having a peak wavelength of about 510-530 nm, but a mid-tone green color in which white peaks of a longer wavelength-based red color are added together. (greenish white) LED device that emits light.

A pastel color LED device using a single LED chip is disclosed in Korean Patent Application Publication No. 2002-0025696, "Light Emitting Diode," filed on September 17, 2001, by Citizen Denshi. According to the patent application of Citizen Denshi, the fluorescent resin of the wavelength conversion material and the pigment particle of the wavelength absorbing material are dispersed in the molding resin in the epoxy resin of the LED. YAG is used as a fluorescent particle, and dye is used as a pigment particle.

The LED device disclosed in the Citizen Denshi patent application emits light of pastel color in the following manner. That is, part of the primary color light emitted from the LED chip is fluorescently converted into light having a longer wavelength by the fluorescent particles. The other part of the primary color light and the part of the fluorescently changed light are absorbed by the dye particles, and the remaining part of the primary color light and the remaining part of the fluorescently converted light are combined to emit light of the pastel color as a whole. Referring to the CIE chromaticity diagram disclosed in FIG. 6 of the patent application, the marking is also indicated in the region emitting light of the orange, yellow and green light regions adjacent to the white light region.

However, the pastel-colored LED device such as orange according to the prior art has a disadvantage in that the brightness of light emitted to the outside of the LED device is low because some of the primary color light and the fluorescently converted light are absorbed by the dye particles. In addition, the pastel-colored LED device such as orange according to the prior art has a short lifespan and a low reliability because its lifespan is only about 500-1000 hours.

The technical problem to be achieved by the present invention is to provide a pastel-color LED device and a method of manufacturing the same, which emits light such as orange with a long brightness and long life.

Another technical problem to be achieved by the present invention is to provide a pastel-color LED device and a method of manufacturing the same, which emits light such as orange, which is not competitive in color distribution and price competitive.

Orange, yellow or green pastel color LED device according to the present invention for achieving the above technical problem is the LED chip mounting member, LED chip, resin for the mold and Sr _1-x S _x : Eu phosphor (where x is 0.3 to 0.7). However, no wavelength absorbing material such as dye is included.

The LED chip mounting member is a means to which the LED chip is attached and mounted, and the type thereof is not particularly limited. For example, the LED chip mounting member may be a printed circuit board (PCB) or a lead frame. The LED chip mounting member may further include a reflecting plate or a reflecting cup.

The LED chip emits blue or cyan light. In order to emit orange, yellow or green pastel color light, the LED chip preferably emits light having a wavelength of 490 to 520 nm. There is no particular limitation on the way the LED chip is mounted. For example, the LED chip may be mounted on the LED chip mounting member so that the light emitting area faces upward or may be mounted in a flip chip method.

The mold resin may be formed of a transparent material, for example, a transparent epoxy resin.

The Sr _{1- x} S _x : Eu phosphor emits orange light while being excited by the light emitted from the LED chip and then returning to a stable state. Therefore, as more Sr _{1- x} S _x : Eu phosphors are included, light of a pastel color close to orange is emitted. The Sr _{1- x} S _x : Eu phosphor is preferably evenly dispersed in the mold resin.

According to another aspect of the present invention, the phosphor may occupy 0.1 to 50% by weight of the weight of the resin for the mold, the appropriate amount of phosphor is the wavelength of the light emitted from the LED chip, the wavelength of the pastel color light finally to obtain And it can vary according to the structure etc. of the resin for mold.

The method of manufacturing the orange, yellow and green pastel color LED device according to the present invention for achieving the above technical problem, first, by mounting a blue or cyan LED chip on the LED chip mounting member, and attaching the LED chip Electrically connected In addition, a mother resin including an epoxy resin and Sr _{1- x} S _x : Eu phosphors mixed with the epoxy resin (where x is 0.3 to 0.7) is prepared and molded into the mother resin to seal the LED chip. It includes a step.

According to one aspect of the present invention, the molding process may be performed using a potting method, a screen pattern mask method or a transfer molding method.

According to another aspect of the present invention, first, the liquid epoxy resin including the main body and the curing agent is first mixed at room temperature, and then the liquid epoxy resin is mixed at a temperature of 70 to 100 ° C. and a pressure of 1 to 30 Torr. The first curing step of semi-curing is carried out. Then, the Sr _1-x S _x : Eu phosphor is added to the semi-cured liquid epoxy resin at room temperature, followed by secondary mixing to prepare the parent resin. Subsequently, after apply | coating the said base resin on the said LED chip, the 2nd cure which hardens the said base resin under temperature and normal pressure of 120 degreeC or more is implemented.

Details of other embodiments are included in the detailed description and drawings of the embodiment.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms. The present embodiments are merely provided to make the disclosure of the present invention complete, and to fully convey the scope of the invention to those skilled in the art, and the spirit of the present invention is defined by the scope of the claims. Like reference numerals refer to like elements throughout.

1A to 1C are schematic cross-sectional views of lamp type, chip type and top type pastel color LED elements emitting light such as orange according to a preferred embodiment of the present invention.

1A to 1C, the LED device includes an LED chip 14, members 20 and 24 that can be mounted by attaching the LED chip 14, and a mold resin 10 surrounding the LED chip 14. ) And at least the phosphor 12 dispersed in the mold resin 10. However, it does not contain a wavelength absorbing material such as a dye as disclosed in the aforementioned Citizen Denshi patent application. The cross-sectional structure of such an LED device is hardly different from the LED device according to the prior art. Therefore, detailed description of the structure of the LED device is omitted in the present specification. Unexplained reference numeral 16 denotes an adhesive, 18 a bonding wire, 22 a lead connected to an external electrode, and 26 a mold cup.

However, the LED device according to the embodiment of the present invention has the following features.

First, in order to enable the LED device to emit orange, yellow or green pastel light, a blue or cyan LED chip 14 emitting light in a specific wavelength range is used. The LED chip 14 can appropriately select a specific wavelength range of blue or cyan in consideration of the characteristics of the phosphor, that is, the range of the wavelength at which the phosphor is excited or the final color of the emitted light to be obtained. In the case of the present invention, the wavelength range of the LED chip 14 is about 490-520 nm because the objective of the present invention is to use Sr _{1- x} S _x : Eu phosphor 12 and obtain orange, yellow or green light. It is preferable to be between.

Second, in this embodiment, Sr _{1- x} S _x : Eu phosphor 12 is used as the phosphor. Here, x is between about 0.3-0.7, and europium (Eu) serves as an ion for activating SrS. In addition, the phosphor 12 may further include calcium (Ca), which is a kind of impurity that may or may not be included depending on the manufacturing process of the phosphor 12 and does not significantly affect the characteristics of the emitted light. The Sr _{1- x} S _x : Eu phosphor 12 used in this example absorbs light of about 450-550 nm to emit red light having a peak wavelength of about 615 nm. In this case, the position on the CIE chromaticity diagram of the fluorescently converted orange light is approximately x = 0.632 and y = 0.368.

The LED device according to the present embodiment emits pastel colors such as orange in the following manner. That is, a part of the blue or cyan light emitted from the LED chip 14 is absorbed by the Sr _1-x S _x : Eu phosphor 12, but the other part is emitted to the outside of the mold resin 10 as it is. Sr _{1- x} S _x : When blue light or the like is absorbed in the Eu phosphor 12, Sr _1-x S _x is excited with the aid of Eu, and then returns to a stable state and emits fluorescence-converted red light. Although the peak wavelength of the fluorescence-converted red light may vary slightly depending on the x value, there is no significant effect on the characteristics of the emitted light when x is between 0.3 and 0.7. After all, Sr _{1- x x} S: Eu phosphor (12) and the light blue or turquoise Sr _{1- x} S _x is not absorbed intact release in: Eu is absorbed by the phosphor 12, the light of the orange series fluorescent conversion that is emitted In combination, the LED device ultimately emits pastel colored light such as orange.

The amount of light absorbed in the Sr _1-x S _x : Eu phosphor 12 and the amount of light not absorbed vary depending on the amount of Sr _{1- x} S _x : Eu phosphor 12 dispersed in the mold resin 10. In the present embodiment, the Sr _{1- x} S _x : Eu phosphor 12 may account for about 0.1-50% by weight of the mold resin 10. More specifically, in the case of an LED device manufactured using a liquid epoxy resin in which phosphors are mixed, such as a potting method or a screen pattern mask method, the Sr _1-x S _x : Eu phosphor 12 may be a resin 10 for molding. About 0.1-30% by weight, more preferably about 1-30% by weight. In the case of an LED device manufactured by using a solid epoxy resin tablet in which phosphors are mixed as in the transfer molding method, the Sr _{1- x} S _x : Eu phosphor 12 is about 0.1- about the weight of the resin 10 for a mold. 50%, more preferably in the range of about 2-30% by weight.

2 shows a graph in which the spectra of light emitted from the LED element are measured according to the amount of Sr _{1- x} S _x : Eu phosphor 12. 2 is a case where no Sr _1-x S _x : Eu phosphor 12 is added, and B, C, and D graphs of FIG. 2 are Sr _1-x S _x : E u phosphors 12. 3 wt%, 5 wt% and 7 wt%, respectively. In the above experiment, Sr _{1- x} S _x : Eu phosphor 12 containing about 53 wt% Sr, about 46 wt% S, and about 0.13 wt% calcium as an impurity was used.

2, it can be seen that the peak wavelength is about 510 nm when the Sr _{1- x} S _x : Eu phosphor 12 is not included at all (graph A). This is the intrinsic emission wavelength of the LED chip 14 used in the experiment. In addition, referring to graphs B, C, and D, when Sr _{1- x} S _x : Eu phosphor 12 is included, a second peak wavelength appears when the wavelength is about 615 nm, and Sr _{1- x} S _x : It can be seen that as the amount of the Eu phosphor 12 increases, the intensity at the second peak wavelength also increases. In addition, the Sr _{1- x} S _x : Eu phosphor 12 is referred to as Ca _{1- x} S _x : Eu phosphor (patent application filed on the same date as the filing date of the present application, "Pastel color light emitting diode element and its manufacturing method", Compared to the agent file number (PN055368KR), a small amount is used, and a greater amount of light is emitted from the light emitted from the LED chip.

3 is a graph showing a position on a CIE chromaticity diagram of an LED device corresponding to the graphs A to D described above. In the CIE chromaticity diagram of FIG. 3, A is X = 0.0943, Y = 0.5814, B is X = 0.4084, Y = 5814, C is X = 0.4525, Y = 0.4551 and D is X = 0.4824 and Y = 0.4517. Indicates. Referring to FIG. 3, it can be seen that the LED device according to the present invention in which Sr _{1- x} S _x : Eu phosphor 12 contains a predetermined amount emits orange, yellow or green pastel color light, and It can be predicted that, depending on the amount of Sr _{1- x} S _x : Eu phosphor 12 contained, it will be located at some point on the straight line connecting A to D (Grassman's second law of color, however, a straight line The graph may vary depending on the emission wavelength of the LED chip). In this case, including the _{1- x} Sr _x S: Eu phosphor when the amount of the 12 is small, the emission of green pastel color light but, Sr _1-x S _x: Eu, the amount of the phosphor 12 is relatively large In this case, it can be expected to emit orange pastel color light.

4 is a graph showing a comparison of the brightness of the LED device according to an embodiment of the present invention and the LED device according to the prior art. In FIG. 4, A to D represent luminances of the LED devices corresponding to the above-mentioned graphs A to D of FIG. 2, and E to G are measured for PSG38, PSY29, and PSY23 products, which are pastel color LED devices respectively released by Citizen. It is. Referring to FIG. 4, although the LED device according to the present invention gradually decreases in brightness as the amount of Sr _{1- x} S _x : Eu phosphor 12 increases, the brightness of the LED device according to the present invention is much higher than that of the LED device according to the prior art. It can be seen that.

In addition, the LED device according to the present invention has an average lifetime of about 50,000 to 100,000 hours, which is much longer than the LED device according to the prior art.

Therefore, in the present embodiment, the LED is orange, yellow or green to emit light pastel _{1- x} Sr _x S: Eu phosphor amount of 12: Eu using the phosphor 12, and, Sr _{1- x} S _x You can adjust the to obtain pastel colors in the desired wavelength range. In addition, since the LED device according to the present invention does not use any dye dyes, the LED device according to the prior art not only has a high luminance but also a long life.

Third, the pastel color LED device according to the present invention may be manufactured so that the Sr _1-x S _x : Eu phosphor 12 is evenly dispersed in the resin 10 for a mold. How uniformly the phosphor is dispersed in the mold resin 10 also affects the emitted light characteristics of the LED element. In general, phosphors tend to be precipitated because they have a higher specific gravity than epoxy resins. Sr _{1- x} S _x : E u phosphors 12 are uniformly dispersed in order to manufacture pastel color LED devices having a desired color with less color dispersion. It is desirable to have. Two steps, as disclosed in Korean Patent Application No. 2003-0084173, "Method of Manufacturing a White Light Emitting Diode Device Including a Two-Step Cure Process," filed on November 25, 2003 by the same applicant as the applicant of the present patent. By using the curing process, it is possible to manufacture an LED device in which the Sr _{1- x} S _x : Eu phosphor 12 is evenly dispersed in the mold resin 10. The patent application specification is hereby fully incorporated by reference.

Hereinafter, an orange, yellow, or green pastel color LED device manufacturing method including a two-step curing process will be briefly described. However, the manufacturing method of the LED device according to the present invention is not limited to the manufacturing method using a two-step curing process. That is, the LED device according to the present invention can also be manufactured using various known manufacturing methods. For example, an LED device may be manufactured by a potting method or a screen pattern mask method using a mother resin containing the Sr _{1- x} S _x : Eu phosphor 12 which has not been subjected to a two-step curing process, or Sr _{1- x} S _x : Eu The LED device may be manufactured by a transfer molding method using a tablet of the mother resin containing the phosphor 12. In the present specification, the 'matrix resin' refers to a composition in which an Sr _{1- x} S _x : Eu phosphor 12 in a state before being coated or molded on an LED chip and an epoxy resin which is a resin for a mold are mixed.

FIG. 5 is a graph showing a thermal budget applied when fabricating a pastel-colored LED device such as an orange including a two-step curing process according to an embodiment of the present invention.

Referring to FIG. 5, first, a main epoxy and a curing agent are mixed first to prepare a liquid epoxy resin. In the first mixing step, an Sr _{1- x} S _x : Eu phosphor may be further added. However, no further silicone resin or EMC powder is added in the primary mixing process. Subjects can be, for example, one of cresol novolac epoxy, phenol novolac epoxy or bisphenol A epoxy or mixtures thereof. In addition, the curing agent may be one of an anhydride, an aromatic amine modified product, or a phenol novolak epoxy, or a mixture thereof. If necessary in the primary mixing step, a curing accelerator such as an imidazole compound or an amine compound may be further added to promote the curing reaction.

Subsequently, a primary curing step is performed on the liquid epoxy resin. The first curing process is performed for a predetermined time t ₄ -t ₁ . The temperature and time of the first cure step are mutually dependent, in particular the heating time at temperature T ₁ may vary depending on the heating temperature of the liquid epoxy resin. For example, when the temperature T ₁ is about 80-100 ° C., the temperature increase time (t ₂ -t ₁ ) is about 30 minutes, the heating time (t ₃ -t ₂ ) is about 1 to 2 hours and the temperature reduction time (t ₄ -t ₃ ) can be about 30 minutes. In FIG. 5, T ₀ represents room temperature. The first curing process is carried out in a low pressure state, but the reason for performing the process in a low pressure state is to prevent bubbles from occurring. The low pressure may be about 1-30 torr. As a result of the above first curing process, the liquid epoxy resin is aged into an epoxy resin in a semi-cured state.

Subsequently, referring to FIG. 5, a mother resin is produced by performing a second mixing step with respect to the semi-cured epoxy resin. The 2nd mixing process is a process for making the raw material of semi-hardened epoxy resin mix better. In the case where the Sr _{1- x} S _x : Eu phosphor is added in the first mixing step, the phosphor is also mixed together. In the second mixing step, the required amount or insufficient amount of the phosphor is added. The final amount of Sr _{1- x} S _x : Eu phosphor contained in the mother resin may vary depending on the characteristics of the color of the pastel-colored LED device. For example, based on the weight of the parent resin, the Sr _1-x S _x : Eu phosphor may be about 1-60% by weight of the parent resin. A second mixing process, there is no particular limitation on the performed at room temperature (T _0), the process time (t ₅ t _4).

Next, the LED chip is encapsulated using the mother resin in which the second mixing process is completed. Here, the LED chip is attached to and mounted on the LED chip mounting member using a conductive or nonconductive adhesive. In addition, if necessary, the wire bonding process is completed and electrical connection to the LED chip is completed. As the sealing step, for example, as described above, a potting method or a screen pattern mask method can be used.

Subsequently, referring to FIG. 5, a second curing process of heat-treating the resultant to which the matrix resin is applied is performed. The second curing step is a step for completely curing the parent resin. The second curing process can also be carried out at atmospheric pressure, and is carried out for a predetermined time t ₇ t ₆ at a temperature T ₂ higher than the temperature T ₁ of the first curing process. For example, the heating step of the second curing process may be carried out at a temperature of about 120-130 ° C. for about 1-2 hours. More specifically, the second curing process includes a temperature raising step (t ₆ t ₅ ) of about 30 minutes, a heating step (t ₇ t ₆ ) of about 1 hour at a temperature of about 130 ° C., and a temperature reduction step (t ₈ ) of about 30 minutes. t ₇ ). In the second curing process, the heating time and the heating temperature are mutually dependent.

In the case of this two-step curing process, since the viscosity of the epoxy resin decreases significantly during the second curing process, which is the final heating step, the phosphor is prevented from being precipitated under the mold resin such as epoxy resin. can do. As a result, since the Sr _{1- x} S _x : Eu phosphor is evenly dispersed in the mold resin, it is possible to produce an LED device having excellent characteristics with little color dispersion.

According to the present invention, a blue or cyan LED chip and Sr _{1- x} S _x : Eu are used as phosphors to provide a pastel color LED element such as orange with high luminance. In addition, the LED device according to the present invention can not only manufacture LED devices having various shades of orange, yellow or green by controlling the amount of Sr _1-x S _x : Eu added, but also have relatively long lifespan of the LED devices. Long as

In addition, the LED device according to the present invention is not only excellent in optical characteristics because the color distribution is not dispersed, and also has a cost competitiveness because the manufacturing process is simple.

Claims (7)

LED chip mounting member; A blue or cyan LED chip mounted on the LED chip mounting member; A resin for a mold encapsulating the LED chip; It is evenly dispersed in the resin for the mold and comprises a Sr _1-x S _x : Eu phosphor (where x is 0.3 to 0.7) for fluorescence conversion of light emitted from the LED chip, The LED chip emits light having a wavelength of 490-520nm, The phosphor is an orange, yellow or green pastel color light emitting diode device, characterized in that occupies 0.1 to 50% by weight of the resin for the mold. delete delete Mounting and attaching a blue or cyan LED chip on the LED chip mounting member and electrically connecting the LED chip; Preparing a mother resin including an epoxy resin and Sr _1-x S _x : Eu phosphors mixed with the epoxy resin, wherein x is 0.3 to 0.7; In the orange, yellow or green pastel color light emitting diode manufacturing method comprising the step of molding the matrix resin to encapsulate the LED chip, The matrix resin preparation step, Firstly mixing the liquid epoxy resin including the main agent and the curing agent at room temperature; A first curing step of semi-curing the liquid epoxy resin at a temperature of 70 to 100 ° C. and a pressure of 1 to 30 torr; And adding the Sr _1-x S _x : Eu phosphor to the semi-cured liquid epoxy resin at room temperature and performing secondary mixing. The molding step, Applying the matrix resin on the LED chip; And a second curing step of curing the parent resin at a temperature of 120 ° C. or higher and at atmospheric pressure. The method of claim 4, wherein the molding step is performed by using a potting method, a screen pattern mask method, or a transfer molding method. delete An orange, yellow or green pastel color light emitting diode manufactured by the method of claim 4.

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