KR100735391B1 - Light emitting diode packet having wide beam angle and improved stability - Google Patents

Abstract

An LED(Light Emitting Diode) package having a wide beam angle and improved stability is provided to prevent damage due to internal thermal stress and external impact by arranging first and second encapsulation units having different thermal-physical properties on upper and lower sections of an LED package, respectively. First and second lead frames(110,120) being separated from each other are made of thermal and electric conductors. An LED chip(130) is arranged on an upper surface of the first lead frame toward the second lead frame to be electrically connected to the first and second lead frames. A package body(140) surrounds at least part of the first and second lead frames to fix them, and thus an inclined inner surface of the package body forms a cup unit at a circumference of the LED chip. A first encapsulation unit(150) encapsulates the LED chip and gap-fills the cup unit, partially. A second encapsulation unit(160) is arranged over the first encapsulation unit. The second encapsulation unit has hardness greater than that of the first encapsulation unit and optical property different from the first encapsulation unit. The first and second encapsulation increase a beam angle based on an optical property difference between them.

Description

LIGHT EMITTING DIODE PACKET HAVING WIDE BEAM ANGLE AND IMPROVED STABILITY

1 is a cross-sectional view of an LED package according to the prior art.

2 is a cross-sectional view of the LED package according to the first embodiment of the present invention.

3 is a view for explaining a directivity angle characteristic of the LED package of FIG.

4 is a cross-sectional view of the LED package according to the second embodiment of the present invention.

5 is a cross-sectional view of an LED package according to a third embodiment of the present invention.

6 is a cross-sectional view of the LED package according to the fourth embodiment of the present invention.

7 is a cross-sectional view of an LED package according to a fifth embodiment of the present invention.

8 is a cross-sectional view of an LED package according to a sixth embodiment of the present invention.

<Explanation of symbols of main parts in drawings>

110, 120: lead frame 130: LED chip

140: package body 142: inclined surface

150, 160: sealing part 152, 164: light diffusing agent

162: filler for increasing the refractive index

The present invention relates to a light emitting diode, and more particularly, to a light emitting diode package having improved directivity angle and stability of emitted light.

Light emitting diodes, or LEDs (Light Emitting Diodes), are semiconductor devices for generating light of various colors when a current is applied. The color of light generated by the LED is mainly determined by the chemical constituents of the semiconductor of the LED. The demand for these LEDs is steadily increasing because they have several advantages over filament-based light emitting devices, such as long life, low power, excellent initial driving characteristics, high vibration resistance, and high tolerance for repetitive power interruptions.

Such LEDs are used in the form of packages, and one example of a prior art LED package is shown in cross section in FIG.

Referring to FIG. 1, the LED package 10 includes a pair of conductive patterns 14 and 16 formed on the substrate 12 and an LED chip 18 mounted on the conductive pattern 14. The LED chip 18 is usually electrically connected to the conductive patterns 14 and 16 by wires (not shown). The package sidewall 20 is formed around the LED chip 18, and a transparent resin is filled in the concave cup portion formed by the package sidewall 20 to form the encapsulation portion 22.

The LED package 10 of this configuration is configured to emit upward the light generated from the LED chip 18 at a predetermined angle. However, there is a disadvantage that the upward emission angle of light is limited.

As shown in FIG. 1, the LED chip 18 operates to generate light at its focal point F. At this time, the light L1 is emitted upward at a predetermined angle α with respect to the axis A, which is the normal of the LED chip 18, and the light L2 is an angle β larger than the angle α with respect to the axis A. Is emitted upwards). In this case, the light L1 is emitted to the outside through the top surface of the encapsulation portion 22, and the light L2 is reflected on the side wall 20 and then upwardly emitted. Therefore, the angle α becomes the orientation angle of the LED package 10.

If the direction angle is small, the amount of light hitting the side wall 20 increases, resulting in a decrease in the overall light emission efficiency. In addition, since the emission of light is limited to a narrow range, it is not suitable for lighting using a plurality of LED packages 10. Therefore, it is desirable to be able to increase the orientation angle.

This orientation angle is mainly determined by the height of the side wall 20 and the width of the cup portion. For example, by lowering the height of the side wall 20 or increasing the width of the cup part, the direction angle may be increased. However, since the height of the side wall 20 is required to a certain value in consideration of the process conditions, there is a limit to reducing it. In addition, increasing the width of the cup portion is also undesirable since the volume of the LED package 10 also increases.

Meanwhile, a method of protruding the encapsulation part 22 in a dome shape onto the sidewall 20 in order to increase the direction angle may be applied. However, this requires dotting the resin, which is disadvantageous in that the process is difficult and the number of detailed steps is increased.

In addition, when the encapsulation portion 22 protrudes in a dome shape, an impact applied to the encapsulation portion 22 from the outside may be transmitted to the internal LED chip 18 as it is, thereby damaging it. In addition, if the encapsulation portion 22 does not absorb the thermal stress of the LED chip 18 smoothly, the LED chip 18 may be damaged by its own thermal stress.

Therefore, the present invention has been made to solve the above-described problems of the prior art, an object of the present invention is to improve the directivity of the light by placing the first and second encapsulation with different optical characteristics in the lower and upper layers LED package To provide.

It is another object of the present invention to provide an LED package having improved stability by preventing both internal thermal stress and external shock damage by disposing first and second encapsulation parts having different thermal-physical properties in a lower layer and an upper layer. will be.

In order to achieve the above object of the present invention, an LED package provided according to the present invention includes: first and second lead frames disposed at intervals from each other and made of thermal and electrical conductors; An LED chip disposed on an upper surface of the first lead frame toward the second lead frame and electrically connected to the first and second lead frames; A package body in which an inclined inner surface forms a cup around the LED chip while surrounding and fixing at least a portion of the first and second lead frames; A first encapsulation portion which at least partially fills the cup portion while encapsulating the LED chip; And a second encapsulation part having a higher hardness than the first encapsulation part and an optical characteristic difference from the first encapsulation part, and disposed as an upper layer of the first encapsulation part. The first and second encapsulation portions are directed by emitting at least some of the light traveling from the LED chip toward the inclined inner surface of the package body based on the difference in optical characteristics therebetween without hitting the inclined inner surface. Configured to increase the angle.

Preferably, the refractive index of the first encapsulation portion is lower than the refractive index of the second encapsulation portion.

The first encapsulation portion has a hardness of JIS Shore A 0 to JIS Shore A 80.

Preferably, the first encapsulation portion is composed of at least one material selected from the group consisting of silicon gel and silicon including methyl groups.

Preferably, the second encapsulation portion has a hardness of JIS Shore D 20 to JIS Shore D 70.

Preferably, the second encapsulation portion is composed of at least one material selected from the group consisting of silicone including methyl group and silicone including phenyl group.

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

2 is a cross-sectional view of the LED package according to the first embodiment of the present invention. Referring to FIG. 2, the LED package 100 of the present invention is mounted on the first and second lead frames 110 and 120 and the first lead frame 110 disposed to face each other and electrically connected thereto. The package body 140 may be a sidewall that fixes the chip 130 and the first and second lead frames 110 and 120.

The first LED frame 110 has a base 112 on which the LED chip 130 is mounted, a connection portion 114 extending obliquely upwardly outward from the base 112 and an extension extending horizontally again from the connection portion 114. Section 116. The base 112 is mounted with an LED chip 130 and electrically connected by wires (not shown) or solder bumps. The connection part 114 and the extension part 116 are surrounded by the package main body 140 and fixed, and the end of the extension part 116 protrudes out of the package main body 140. In this way, the lead frame 110 is firmly fixed to the package body 140 while effectively dissipating heat from the LED chip 130 to the outside.

In addition, the second lead frame 120 includes a base 122 connected to the LED chip 130 by a wire 132, a connecting portion 124 extending upwardly inclined outward from the base 122, and the connecting portion 124. And an extension 126 extending horizontally again from. Since the second lead frame base 122 has an upper surface having the same height as the first lead frame base 112, it is easy to manufacture the entire lead frames 110 and 120, and to connect and package the wires 132. . In addition, since the connection part 124 and the extension part 126 are surrounded by the resin of the package main body 140 and the ends of the extension part 126 protrude out of the package main body 140, the second lead frame 120 is packaged. It is firmly fixed to the main body 140.

The package body 140 forms a concave cup portion surrounding the LED chip 130 while fixing the first and second lead frames 110 and 120. The cup portion is formed by the inner inclined surface 142 of the package body 140. In the present embodiment, the package body 140 is preferably formed of a resin, but is not necessarily limited thereto. For example, it may be formed of a ceramic substrate and sidewalls as shown in FIG. 1.

First and second encapsulation parts 150 and 160 are formed in the cup part formed by the inner inclined surface 142. The first and second encapsulation parts 150 and 160 are formed by filling a transparent resin into a cup part and then curing the cup. In this case, the resin of the first encapsulation part 150 has a lower refractive index than the resin of the second encapsulation part 160.

The first encapsulation part 150 is formed of a material having a lower hardness than the second encapsulation part 160 in a hardened state. Preferably, the resin of the first encapsulation part 150 has a relatively low hardness and high elasticity, and the second encapsulation part 160 is selected from a material having high hardness even if the elasticity is low. In this way, the first encapsulation unit 150 may absorb the thermal stress caused by the temperature rise of the LED chip 130 to prevent damage to the LED chip 130, and the second encapsulation unit 160 may be externally impacted. It is not deformed or damaged even though it can maintain excellent lens function. In addition, since the external shock is absorbed by the elastic first encapsulation unit 150, the LED chip 130 may be prevented from being damaged by the external shock.

As the first encapsulation part 150, a soft gel or an elastomer-based resin may be used, and a preferred hardness range is about JIS Shore D 20 to JIS Shore D 70. Preferred examples of the first encapsulation unit 150 include Dow Corning's TX2305, EG6301 silicon, and Shin-Etsu's X-35-346, X-35-140 silicon, and the like.

Among them, silicon has excellent optical properties because silicon has very little change by short wavelength of light such as yellowing and high refractive index. In addition, unlike epoxy, since the gel or elastomer state is maintained even after curing, the LED chip 130 may be more stably protected from heat stress, vibration, and external shock.

Hard resin can be used as the 2nd sealing part 160, and a preferable hardness range is JIS Shore D20-JIS Shore D70. Preferred examples of the second encapsulation unit 160 include KN series silicon of Dow Corning Corporation, LPS series silicon of Shin-Etsu Corp., and the like.

The first and second encapsulation parts 150 and 160 may include a phosphor for converting wavelengths and / or a diffusion agent dispersed therein.

Meanwhile, although the LED chip 130 is illustrated as a vertical structure LED chip electrically connected to the first lead frame base 112 by solder bumps (not shown), the LED chip 130 may be connected by a wire (not shown).

An effect obtained when the refractive index of the first encapsulation part 150 is smaller than the refractive index of the second encapsulation part 160 will be described with reference to FIG. 3. The LED package 100 shown in FIG. 3 has the same configuration as that shown in FIG.

In the LED package 100 as described above, when the LED chip 130 operates so that light having a predetermined angle β from the focal point F with respect to the axis A which is the normal line of the chip 130 is emitted upward. If the first and second encapsulation portions 150 and 160 have the same refractive index, the light will hit the inclined surface 142 and be reflected. This is indicated by a dotted line by the reference numeral L '.

However, as in the present invention, if the refractive index of the first encapsulation unit 150 is smaller than the refractive index of the second encapsulation unit 160, the light is the first encapsulation unit 150, as indicated by reference numeral L indicated by a solid line. First refraction at the interface between the second encapsulation 160 and the second refraction at the interface between the second encapsulation 160 and the external medium, for example, air, is emitted to the outside.

Comparing the LED package 100 of the present invention with the LED package 10 of the prior art shown in Figure 1 it can be clearly seen the difference. To this end, the interval between the inclined surface 142 of the LED package 100 of the present invention is equal to the width of the cup portion of the LED package 10 of Figure 1, the height of the inclined surface 142 of the LED package 100 is shown in FIG. Assume that it is equal to the height of the side wall 20 of the LED package 10 of 1. That is, it is assumed that the LED package 100 of the present invention has the same emission window as the LED package 10 shown in FIG. In this way, the emission angle β of FIG. 3 becomes equal to the emission angle β of FIG. 1. However, at the same emission angle β, the LED package 100 of the present invention emits light upwards without hitting the inclined surface, while the LED package 10 of FIG. It will hit the slope. It can be seen that the above angle β is within the range of the directivity angle in the LED package 100 of the present invention, but outside the range of the directivity angle α in the LED package 10 of FIG. 1. As a result, the LED package 100 of the present invention is increased in orientation angle compared to the LED package 10 of the prior art.

As such, when the directivity angle is increased, the light extraction efficiency may be increased and the directivity characteristic may be further improved.

An LED package 100-2 according to a second embodiment of the invention is shown in cross section in FIG. 4.

Referring to FIG. 4, the LED package 100-2 according to the present exemplary embodiment is except that the hard second encapsulation portion 160-2 protrudes in a dome shape over the top of the package body 140. The same configuration as the LED package 100. The rest of the configuration is the same as that of the LED package 100 and therefore the same reference numerals will be given and the description will not be repeated.

In the LED package 100-2 of the present embodiment, since the hard second encapsulation portion 160-2 has a refractive index greater than that of the soft first encapsulation portion 150, the LED package 100-2 is formed in the LED chip 130. The directing angle of the light can be further increased.

An LED package 100-3 according to a third embodiment of the invention is shown in cross section in FIG. 5.

Referring to FIG. 5, the LED package 100-3 according to the present embodiment has the LED package of FIG. 2 except that the hard second encapsulation portion 160-3 includes the filler 162 for increasing the refractive index. It is the same structure as 100. The rest of the configuration is the same as that of the LED package 100 and therefore the same reference numerals will be given and the description will not be repeated.

When the filler for increasing the refractive index 162 is preferably uniformly dispersed in the second encapsulation portion 160-3, the second encapsulation portion 160-3 may have an increased refractive index than that of the first encapsulation portion 150. The effect is as described above with reference to FIG.

On the other hand, the preferred refractive index increasing filler 162 includes SiO ₂ having a refractive index of 1.45 or more, a transmittance of 80% or more, TiO ₂ having a refractive index of 2.5 or more, and a reflectance of 90% or more, and the smaller the particle size to nano size, the more effective. .

On the contrary, the second encapsulation portion 160-3 has a larger refractive index than the first encapsulation portion 150 but the same hardness, and instead of the filler 162 for increasing the refractive index in the second encapsulation portion 160-3. The fine filler for increasing hardness may be uniformly dispersed. Even in this way, the same effects as above can be obtained.

An LED package 100-4 according to a fourth embodiment of the invention is shown in cross section in FIG. 6.

Referring to FIG. 6, the LED package 100-4 of this embodiment is similar to the LED packages 100 and 100-3 of FIGS. 2 and 5, but has a light diffusing agent in the hard second encapsulation portion 160-4. The point at which 164 is added is distinguished. The rest of the configuration is the same as that of the LED packages 100 and 100-3, and therefore the same reference numerals will be given and will not be described again.

In the LED package 100-4 of the present embodiment, the finely dispersed light diffusing agent 164 preferably uniformly dispersed in the second encapsulation portion 160-4 is the LED chip 130 or the focus F thereof. Refract the light (L1) arrived at. The light refracted by the light diffusing agent 164 is emitted out of the second encapsulation portion 160-4 at an angle that is wider than the propagation angle as a whole. In this way, as described above with reference to FIG. 2, light generated from the LED chip 130 may be emitted from the LED package 100-4 at a wider angle. In other words, the effect of increasing the aiming angle can be obtained.

Meanwhile, the light diffusing agent 164 may be a polymer, an opal mineral, SiO 2, or the like.

Hereinafter, an LED package according to a fifth embodiment of the present invention will be described with reference to FIG. 7.

Referring to FIG. 7, the LED package 100-5 according to the present embodiment includes the LEDs described above in the configuration of the first and second lead frames 110 and 120, the LED chip 130, and the package body 140. Same as the package 100. However, in the cup portion formed around the LED chip 130 by the package body 140, a soft first encapsulation portion 150-5 in which the light diffusing agent 152 is mixed is formed, and the first encapsulation portion 150 is formed. -5) The point where the hard 2nd sealing part 160-5 which consists of a dome-shaped cover or a lens is attached is distinguished. The second encapsulation portion 160-5 is coupled to the first encapsulation portion 150-5 by the adhesive 166, but may be attached by other suitable means.

The light diffusing agent 152 diffuses the light generated by the LED chip 130 and emits it out of the first encapsulation part 150-5, thereby increasing the directing angle of the light. In addition, the second encapsulation portion 160-5 attached to the upper surface of the first encapsulation portion 150-5 further increases the directing angle of the light emitted from the first encapsulation portion 150-5. By such a configuration, the LED package 100-5 may have an increased orientation angle.

As the light diffusing agent 152, a polymer, an opal mineral, SiO 2, or the like may be used.

An LED package 100-6 according to a sixth embodiment of the present invention is shown in cross section in FIG.

Referring to FIG. 8, the LED package 100-6 of the present embodiment is the LED package 100-5 of FIG. 7 except that the hard second encapsulation portion 160-6 is formed in a dome shape by discharging the resin. Same as). The dome-shaped second encapsulation portion 160-6 may be implemented by precisely discharging the resin or by making the width of the upper end of the package body 140 less than or equal to the threshold.

Meanwhile, the first and second encapsulation parts 150-6 and 160-6 of the present embodiment have the same shape as the first and second encapsulation parts 150 and 160-2 of the LED package 100-2 of FIG. 4. It can also be formed.

As described above, according to the LED package of the present invention, the directing angle of the light can be improved by disposing the first and second encapsulation portions having different optical characteristics in the lower layer and the upper layer. Specifically, a high refractive index second encapsulation is disposed on the first encapsulation having a low refractive index to adjust the angle when light is incident from the first encapsulation to the second encapsulation and emitted from the second encapsulation to the outside. You can increase the angle. In addition, by adding a refractive index increasing filler to the second sealing portion, the refractive index of the second sealing portion may be increased to obtain the above effect. In addition, the directivity angle may be further increased by mixing the light diffusing agent in the first encapsulation portion of the lower layer and configuring the second encapsulation portion of the upper layer in a dome shape.

In addition, the first encapsulation part is made of a soft material having low hardness, and the second encapsulation part is made of a hard material having high hardness, thereby absorbing thermal stress caused by the rise of the temperature of the LED chip, preventing damage to the LED chip, and preventing external impact of the LED. By preventing transmission to the chip, the stability of the LED chip and the LED package can be improved. In addition, the hard second encapsulation portion may not be deformed or damaged even by an external impact, thereby maintaining an excellent lens function.

Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art may vary the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. It will be understood that modifications and variations can be made.

Claims (6)

First and second lead frames disposed at intervals from each other and made of thermal and electrical conductors; An LED chip disposed on an upper surface of the first lead frame toward the second lead frame and electrically connected to the first and second lead frames; A package body in which an inclined inner surface forms a cup around the LED chip while surrounding and fixing at least a portion of the first and second lead frames; A first encapsulation portion which at least partially fills the cup portion while encapsulating the LED chip; And A second encapsulation part having a higher hardness than the first encapsulation part and an optical characteristic difference from the first encapsulation part, and disposed as an upper layer of the first encapsulation part, The first and second encapsulation portions are directed by emitting at least some of the light traveling from the LED chip toward the inclined inner surface of the package body based on the difference in optical characteristics therebetween without hitting the inclined inner surface. LED package, characterized in that configured to increase the angle. The LED package of claim 1, wherein a refractive index of the first encapsulation portion is lower than a refractive index of the second encapsulation portion. The LED package of claim 1, wherein the first encapsulation part has a hardness of JIS Shore A 0 to JIS Shore A 80. The LED package according to claim 1, wherein the first encapsulation part is made of at least one material selected from the group consisting of silicon including silicon gel and methyl group. The LED package of claim 1, wherein the second encapsulation has a hardness of JIS Shore D 20 to JIS Shore D 70. The LED package of claim 1, wherein the second encapsulation part is made of at least one material selected from the group consisting of silicon including a methyl group and silicon including a phenyl group.

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