KR100665180B1 - Light emitting diode package and method of faricatiing the same - Google Patents

Abstract

The present invention relates to a light emitting diode package and a manufacturing method thereof, comprising a package substrate having a lead frame, a light emitting diode mounted on the package substrate to be electrically connected to the lead frame, and a transparent resin to seal the light emitting diode. A light emitting diode package is formed, the light emitting diode package including a molding part having a refractive index gradient of which the average refractive index of the upper region is gradually lowered by the particle distribution of the transparent material having a density and refractive index higher than the density and refractive index of the transparent resin. do.

Light emitting diodes, phosphors, light extraction efficiency, refractive index

Description

LIGHT EMITTING DIODE PACKAGE AND METHOD OF FARICATIING THE SAME}

1 is a cross-sectional view showing a conventional light emitting diode package.

2A to 2C are cross-sectional views of respective processes for explaining a manufacturing process of a light emitting diode package according to an embodiment of the present invention.

3 is a cross-sectional view showing a wavelength conversion type light emitting diode package according to another embodiment of the present invention.

4A and 4B are graphs showing particle distribution and refractive index distribution of the LED package molding part shown in FIG.

<Description of main parts of drawing>

11,21: lower package substrate 12,22: upper package substrate

13a, 13b, 23a, 23b: lead frame 15, 25: light emitting diode chip

18,28: transparent resin molding P: phosphor powder

D1, D2, D3: high refractive index transparent material particles

The present invention relates to a light emitting diode package, and more particularly, to a new light emitting diode package having improved light extraction efficiency by improving the refractive index distribution of the resin molding part and a method of manufacturing the same.

In general, the light emitting diodes have excellent monochromatic peak wavelength, excellent light efficiency, and miniaturization, and thus are widely used as various display devices and light sources. A typical light emitting diode package has a structure in which a light emitting diode is protected by a transparent resin molding. In particular, the resin molding part of the white light emitting diode package is used in a form in which phosphor powder is dispersed to obtain white light by converting the wavelength of light.

However, the resin molding part used in the light emitting diode package has a disadvantage of lowering the light extraction efficiency. For example, a nitride semiconductor light emitting device has a refractive index of about 2.4, whereas a resin molding material such as epoxy has a low refractive index of 1.5, so that the total reflection critical angle at the interface is very low. Therefore, there is a problem that the light extraction efficiency is lowered.

In order to improve such a problem, Japanese Patent Laid-Open No. 2001-203392 (published date: 2001.7.27, Applicant: MATSUSHITA ELECTRIC WORKS LTD) discloses a plurality of resin molding parts having different refractive indices as shown in FIG. Using optical materials to form an optical gradient functional film provides a method of lowering the total reflection critical angle.

Referring to FIG. 1, the light emitting diode package 10 includes a lower package substrate 11a on which two lead frames 13a and 13b are formed, and an upper package substrate 11b on which the cavity is provided. The light emitting diode chip 15 is mounted in the cavity region. The light emitting diode chip 15 may have a flip chip structure including a light emitting diode 15a and a chip substrate 15b. The positive electrode (not shown) of the light emitting diode chip 15 may be connected to the upper ends of the lead frames 13a and 13b by wires, respectively.

The molding part 18 surrounding the LED chip 15 is formed in the cavity provided in the upper package substrate 11b. The molding part 18 includes a DLC layer 18a which is a high refractive index material surrounding the LED chip 15, an epoxy resin layer 18b which is an intermediate refractive index formed thereon, and a magnesium fluoride layer 18c having a low refractive index formed thereon. ) Since the resin molding unit 18 gradually decreases the refractive index toward the outside in the direction of the LED 15, the total molding critical angle may be increased step by step during light extraction.

However, the above-described prior art adopts a method of lowering the refractive index by using materials of different materials, and therefore, a separate forming process (ie, a dispensing and curing process) must be performed for each layer. In the case of the type shown in Fig. 1, three iterative molding part forming processes are required, and there is a difficulty in selecting a plurality of materials having different refractive indices.

Therefore, there is a need in the art for a light emitting diode package and a method of manufacturing the same having a new resin molding to more effectively improve the total reflection critical angle in order to improve light extraction efficiency.

SUMMARY OF THE INVENTION The present invention has been made to solve the above technical problem, and an object thereof is to provide a new light emitting diode package which realizes a gradual refractive index gradient distribution formed by unbalanced precipitation of transparent material particles having a higher refractive index and density than transparent resin materials. .

Another object of the present invention is to provide a novel light emitting diode package manufacturing method for forming a gradual refractive index gradient distribution according to an unbalanced precipitation of other transparent material particles having a higher refractive index and density than the transparent resin material.

In order to solve the above technical problem, the present invention

A package substrate having a lead frame, a light emitting diode mounted on the package substrate to be electrically connected to the lead frame, and a transparent resin to seal the light emitting diode, the density being at least higher than the density and refractive index of the transparent resin. The present invention provides a light emitting diode package including a molding part having a refractive index gradient such that an average refractive index of an upper region is gradually lowered in a lower region by particle distribution of a transparent material having a refractive index.

Preferably, the transparent material particles are composed of two kinds of particles of the same material having different particle sizes, and the resin molding part has a particle size having a larger particle size than the particle group having a smaller particle size. Take form.

In a particular embodiment of the invention, the molding part may further comprise phosphor powder, in which case it is preferred that the transparent material is one having a density greater than that of the phosphor.

The transparent material particles preferably used in the present invention have a refractive index of 1.8 to 10. The transparent material particles may be selected from the group consisting of GaP, Si, TiO ₂ , SrTiO ₃ , SiC, cubic or amorphous carbon, carbon nanotubes, ZnO, AlGaInP, AlGaAs, SiN, SiON, ITO, SiGe, AlN and GaN Can be.

In addition, an uneven pattern may be formed on the surface of the molding part to further improve light extraction efficiency.

A package structure in which the present invention can be advantageously employed includes a cavity in which an inner side wall is inclined upward, the cavity is provided as a mounting area of the light emitting diode, and defines a forming area of the molding part.

The present invention provides a novel method of manufacturing a light emitting diode package. The method includes providing a package substrate having a lead frame, mounting a light emitting diode on the package substrate to be electrically connected to the lead frame, and at least a density and refractive index of the transparent resin in a liquid transparent resin. Mixing transparent material particles having a density and a refractive index, sealing the light emitting diode with a transparent resin mixed with the transparent material particles, and having a refractive index gradient such that an average refractive index of the upper region is gradually lowered in the lower region. After the settling time of the transparent material particles, and curing the transparent resin to form a molding.

The main feature of the present invention is the addition of other transparent material particles having a refractive index and density greater than that of the transparent resin material to the liquid transparent resin intentionally causing precipitation, and the distribution of the high refractive index transparent material particles formed thereby in the light extraction direction. It is to form a resin molding portion having a gradually decreasing refractive index gradient distribution. Therefore, not only can the formation process be realized as one time dispensing and hardening, but also the progressive refractive index inclination distribution, rather than the stepwise refractive inclination distribution by the layer, can improve the light extraction efficiency more effectively. Can be.

The present invention also provides a method of mixing two kinds of the same particle group more preferably having different particle sizes in order to form a refractive index gradient distribution by such transparent material particles. In this case, the refractive index gradient distribution can be realized at a faster time. This is very advantageous when forming a resin molding portion in which phosphor powder is mixed. That is, excessive precipitation of the phosphor powder may occur when the pre-curing time is continued, which may cause a problem of uneven distribution of the phosphor powder. Two homogeneous populations can be used to alleviate this problem.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2A to 2C are cross-sectional views of respective processes for explaining a manufacturing process of a light emitting diode package according to an embodiment of the present invention.

As shown in Fig. 2A, the present invention starts with mounting a light emitting diode chip 25 on a package substrate 21 having lead frames 23a and 23b. The package substrate 21 may include a lower package substrate 21a having two lead frames 23a and 23b and an upper package substrate 21b provided with the cavity. The light emitting diode chip 25 may have a flip chip structure including a light emitting diode 25a and a chip substrate 25b. The light emitting diode chip 25 is mounted in the cavity region. The cavity region defines a region in which the resin molding part 28 of FIG. 2C is to be formed, and since the inner side wall has a surface inclined toward the top, it may be used as a reflective surface. Positive electrodes (not shown) of the light emitting diode chip 25 may be connected to the upper ends of the lead frames 23a and 23b by wires, respectively.

The transparent transparent resin is mixed with transparent material particles (D1, D2, D3) having a higher density and refractive index than at least the density and refractive index of the transparent resin, and the liquid mixed resin 28 is mixed with the light emitting diode ( Into the mounting area of (25). The liquid mixed resin 28 is prepared by mixing transparent material particles (D1, D2, D3) having a higher refractive index and density than the resin liquid in a common transparent resin solution such as epoxy (n = 1.5) and silicon.

The high refractive index transparent material particles (D1, D2, D3) are provided by two kinds of the same material particle group having different particle sizes, and are provided by three types (D1, D2, D3) in this embodiment. This is to set the deviation of this precipitation large and to obtain the refractive index gradient more effectively. It is preferable to use the transparent material particle | grain which has a refractive index of 1.8-10. The transparent material particles include, but are not limited to, GaP (n = 3.5), Si (n = 3.4), TiO ₂ (n = 2.9), SrTiO ₃ (n = 2.5), SiC (n = 2.7), cubic or Amorphous carbon (n = 2.4), carbon nanotube (n = 2.0) ZnO (n = 2.0), AlGaInP (n = 3.4), AlGaAs (n = 2.8-3.2), SiN (n = 2.2-2.3), SiON ( n = 2.2), ITO (n = 1.8 to 1.9), SiGe (n = 2.8 to 3.2), AlN (n = 2.2) and GaN (n = 2.4) can be selected and used.

As shown in FIG. 2B, three kinds of particle groups D1, D2, and D3 having different particle sizes are mixed in the initial stage of the mixed resin solution 28, and are proportional to the particle size size as time passes. Precipitation proceeds. That is, the precipitation of the first particle group D1 having the largest particle size proceeds at a high speed, and the precipitation of the third particle group D3 having the smallest particle size proceeds the slowest.

As a result, after the time for obtaining the desired refractive index gradient distribution has elapsed as shown in Fig. 2C, the resin liquid is cured to form the desired resin molding portion 28. In the case of the first particle group D1, most of the precipitate is precipitated, and the lower region provides a high refractive index region A1 close to the high refractive index of the transparent material, and the middle region is the second particle group D2 or the first particle The middle refractive index region A2 in which the group D1 is mainly present is provided, and the upper region provides the low refractive index region A3 in which the first particle group D1 or almost no particle group exists. For ease of understanding, the three regions A1, A2, and A3 have been arbitrarily divided and described. However, those skilled in the art will appreciate that a refractive index gradient distribution gradually decreases from the lower part to the upper part.

As such, conditions such as precipitation time and particle size difference for forming the refractive index gradient distribution may be appropriately selected in consideration of the viscosity of the transparent resin liquid 28 and the refractive index and density of the high refractive index transparent material particles (D1, D2, D3). will be.

2A to 2C, the method of providing and providing the high refractive index transparent material particles in two or more groups having different particle sizes may provide more effective refractive index gradient distribution. In particular, the present embodiment can be advantageously applied to a wavelength conversion type light emitting diode package using phosphor powder.

In general, when the phosphor powder is precipitated excessively, such as high refractive index transparent material particles employed in the present invention, there is a problem that the light conversion characteristics are degraded due to non-uniform phosphor distribution. Therefore, it is preferable to use two or more different particle groups because high refractive index transparent material particles must be effectively precipitated to have a desired refractive index gradient distribution before large precipitation of the phosphor powder occurs.

3 is a cross-sectional view showing a wavelength conversion type light emitting diode package including phosphor powder.

Referring to FIG. 3, the light emitting diode package 30 includes a lower package substrate 31a on which two lead frames 33a and 33b are formed, and an upper package substrate 31b on which the cavity is provided. The light emitting diode chip 35 is mounted in the cavity region. Positive electrodes (not shown) of the light emitting diode chip 35 are connected to the upper ends of the lead frames 33a and 33b, respectively. The molding part 38 surrounding the LED chip 35 is formed in the cavity provided in the upper package substrate 31b.

The resin molding part is formed by a high refractive index transparent material particle group (D1, D2, D3) having three different particle sizes similarly to the shape described in FIG. In contrast, the phosphor powder P has a uniform distribution compared to the inclined distribution of the high refractive index transparent material. As described above, the high refractive index transparent material particle groups D1, D2, and D3 can obtain a fast dispersing effect in a short time. Accordingly, the refractive index gradient distribution can be formed by the desired transparent material particle groups D1, D2, and D3 before the phosphor powder P starts to precipitate in earnest. For this effect, it is preferable to use a high refractive index transparent material having a higher density than the phosphor powder (P), and at least half or all of the particle size groups (D1, D2, D3) are phosphor powder (P). It is preferable to use larger than the average particle size of.

4A and 4B are graphs showing particle distribution and refractive index distribution of the LED package molding part 38 shown in FIG. Here, the x-axis represents the distance along the light extraction direction from the LED chip surface, S represents the surface of the resin molding portion 38.

4A illustrates a weight distribution of particles and phosphors that may appear in the transparent resin molding 38 of FIG. 3. Almost all of the first particle group D1 having the largest particle is precipitated and distributed in the lower region of the molding part, but the medium particle group D2 has a smoother weight distribution, and the smallest third particle group D3. ) Is the least precipitated among the high refractive index transparent resins. On the other hand, although the phosphor powder P precipitated a little, the tendency is very small compared with the transparent material particle group D1, D2, and D3. Therefore, the phosphor powder P has a relatively uniform weight distribution throughout the resin molding portion.

As described above, since the high refractive index transparent material particles (D1, D2, D3) have a higher density than the phosphor powder (P) and form a relatively large and two or more different particle groups, the phosphor powder (P) is used in earnest. This is because the transparent material particle groups D1, D2, and D3 are sufficiently precipitated for refractive index gradient distribution before precipitation.

FIG. 4B illustrates the refractive index gradient distribution shown by the distribution of the high refractive index transparent material particles D1, D2, and D3 as shown in FIG. 4A. For example, when the high refractive index transparent material particles (D1, D2, D3) are TiO ₂ (n = 2.9), the lower refractive index is predominantly distributed to increase the average refractive index of the region to two or more. Gradually, the distribution will be lowered, so that the surface S of the resin molding part will appear as the refractive index (n = 1.5) of the epoxy resin.

As shown in FIG. 4B, the refractive index distribution of the resin molding part according to the present invention has a gradient distribution gradually changing, unlike the stepwise change by the physically divided layers shown in FIG. 1. Therefore, the light emitting diode package according to the present invention can obtain a significantly improved light extraction effect than the conventional package structure having a constant total reflection critical angle (even if diminished) in the interlayer interface.

It is intended that the invention not be limited by the foregoing embodiments and the accompanying drawings, but rather by the claims appended hereto. Accordingly, various forms of substitution, modification, and alteration may be made by those skilled in the art without departing from the technical spirit of the present invention described in the claims, which are also within the scope of the present invention. something to do.

As described above, according to the present invention, in the manufacturing process of the light emitting diode package, another transparent material particle having a refractive index and a density greater than that of the transparent resin is added to the transparent transparent resin to intentionally cause precipitation, and thus the high refractive index formed by As the distribution of the transparent material particles, a resin molding part having a refractive index gradient distribution gradually lowered in the light extraction direction can be formed. Therefore, the formation process can be realized as one-time dispensing and curing as compared with the prior art, and it is possible to improve the light extraction efficiency more effectively by forming a gradual refractive index gradient distribution rather than a stepwise refractive index distribution by the physical layer. can do.

Claims (14)

A package substrate having a lead frame; A light emitting diode mounted on the package substrate to be electrically connected to the lead frame; And A molding part including a transparent resin sealing the light emitting diode, a transparent material having a density and a refractive index higher than at least the density and the refractive index of the transparent resin, and a phosphor powder, wherein the transparent material particles have at least two kinds of the same material having different particle sizes. It consists of a particle group, the particle group having a large particle size has a refractive index gradient that gradually lowers the average refractive index from the lower region to the upper region by the distribution of particles predominantly distributed in the lower portion of the molding than the particle group having a small particle size And the transparent material has a density greater than that of the phosphor. delete delete The method of claim 1, The transparent material particle has a light emitting diode package, characterized in that it has a refractive index of 1.8 to 10. The method of claim 1, The transparent material particles are selected from the group consisting of GaP, Si, TiO ₂ , SrTiO ₃ , SiC, cubic or amorphous carbon, carbon nanotubes, AlGaInP, AlGaAs, SiN, SiON, ITO, SiGe, AlN and GaN LED package. The method of claim 1, Light emitting diode package, characterized in that the uneven pattern formed on the surface of the molding. The method of claim 1, The package substrate includes a cavity in which the inner side wall is inclined toward the top, The cavity is provided as a mounting area of the light emitting diode, and the light emitting diode package, characterized in that for defining the forming area of the molding. Providing a package substrate having a lead frame; Mounting a light emitting diode on the package substrate to be electrically connected to the lead frame; Mixing a transparent material particle and a phosphor powder composed of at least two kinds of the same material particle group having a density and a refractive index higher than the density and the refractive index of the transparent resin and having different particle sizes to the liquid transparent resin-the transparent material is Characterized by having a density greater than that of the phosphor; Sealing the light emitting diode with a transparent resin in which the transparent material particles and the phosphor powder are mixed; And In the lower region, the precipitation time required for the larger particle size of the transparent material particles to predominantly distribute in the lower part of the molding part than the small particle size so that the average refractive index of the upper region gradually decreases. After that, the method of manufacturing a light emitting diode package comprising the step of curing the transparent resin to form a molding. delete delete The method of claim 8, The transparent material particle has a refractive index of 1.8 to 10 characterized in that the light emitting diode package manufacturing method. The method of claim 8, The transparent material particles are selected from the group consisting of GaP, Si, TiO ₂ , SrTiO ₃ , SiC, cubic or amorphous carbon, carbon nanotubes, AlGaInP, AlGaAs, SiN, SiON, ITO, SiGe, AlN and GaN Method of manufacturing a light emitting diode package. The method of claim 8, The forming of the molding part may include forming an uneven pattern on the surface of the molding part. The method of claim 8, The package substrate includes a cavity in which the inner side wall is inclined toward the top, The cavity is provided as a mounting region of the light emitting diode, characterized in that for forming the molding region forming the light emitting diode package.

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