JP2013191883A - Semiconductor light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light emitting device with high brightness and excellent color rendering properties.SOLUTION: A semiconductor light emitting device comprises: a substrate 1; and four light emission parts which are formed on the substrate 1 and have mutually different luminescent colors of red, blue, green and white. In the light emission parts, different LED chips 2, 2, ... are individually covered with resin 7 and resin 8. A reflector 9 is formed so as to surround the four light emission parts as one group.

Description

  The present invention relates to a semiconductor light emitting device using a light emitting element such as a light emitting diode.

  As this kind of semiconductor light emitting device, for example, there is one described in Patent Document 1 (Japanese Patent Laid-Open No. 2000-269551).

  In this conventional structure, a resin b is formed by insert molding or the like so that the lead frame a is fixed, and the LED chip c is formed on the lead frame a with Ag paste f and gold. The LED chip c is a surface-mounted LED that is electrically and mechanically connected by a line d, and that is surrounded and protected by an epoxy resin e.

  In this semiconductor light emitting device, the lead frame a is formed in a specified pattern shape, insert-molded in a resin b with Ag plating, and an LED chip c is placed on the lead frame a with an Ag paste f and a gold wire d. To electrically and mechanically connect and seal with epoxy resin e or silicon resin, then cut leads of unnecessary parts, bend them into U-shapes, and form terminal parts for joining to the mounting board It is a thing.

  In such a semiconductor light emitting device, red, blue, yellow, white light emitted by exciting a blue light with a phosphor, etc., one or more elements having the same color, or RGB having red, blue, green in one product are mounted. There is a light emitting type or the like (for example, see Patent Document 2 (Japanese Patent Laid-Open No. Hei 8-153895)).

JP 2000-269551 A JP-A-8-153895

In the prior art shown in FIG. 12, a plurality of blue light emitting types of white LEDs excited by phosphors and a so-called RGB light emitting type in which LEDs of three primary colors of red, blue and green are respectively mounted. Are mainly mounted on auxiliary light sources for CCDs and light sources for liquid crystal backlights, but they have the following merits and demerits, respectively, and it is difficult to produce LEDs with high brightness and excellent color rendering. It was.
(1) White light-emitting type in which a blue LED is excited with a phosphor:
Emission and conversion efficiency is good, and it is easy to increase the brightness compared to the RGB type that combines the three primary colors of red, blue, and green, but it is a combination with a yellow-green component in which blue is excited with a phosphor. Since the pseudo-white light emission is created, there is a problem that the red component is hardly contained and the color rendering property is poor, and in particular, the red color cannot be reflected.

Depending on the phosphor used, it is possible to include a red component, but the efficiency is low and improvement is still necessary for actual use. Even in that case, the white light emitting type cannot display individual colors such as blue and green, and its usage is limited.
(2) RGB emission type equipped with LEDs of three primary colors, red, blue and green respectively:
This type contains 3 primary color components, so the color rendering is quite excellent. When used for CCD photography or liquid crystal backlights, red coloration stands out, and RGB exists individually. It is also possible to adjust the balance of colors and produce individual colors, create various colors, and it is excellent as illumination, but white light emitted by exciting blue LEDs with phosphors Compared with the type, it is difficult to ensure the brightness due to the problem of individual luminous efficiency.

  Accordingly, an object of the present invention is to provide a semiconductor light emitting device having high luminance and excellent color rendering.

  In order to achieve the above object, the present invention has taken the following measures. That is, the semiconductor light emitting device of the present invention includes a substrate and four light emitting units provided on the substrate, each having red, blue, green, and white light emission colors, and the light emitting unit includes: Different LED chips are individually covered with resin, and reflectors are formed so as to surround the four light emitting portions as a group.

  According to the present invention, a semiconductor light emitting device having high luminance and excellent color rendering can be obtained.

It is sectional drawing of the semiconductor light-emitting device which shows embodiment of this invention. It is a top view of FIG. It is sectional drawing of the semiconductor light-emitting device which shows other embodiment of this invention. FIG. 4 is a plan view of FIG. 3. It is sectional drawing of the semiconductor light-emitting device which shows other embodiment of this invention. FIG. 6 is a plan view of FIG. 5. It is sectional drawing of the semiconductor light-emitting device which shows other embodiment of this invention. FIG. 8 is a plan view of FIG. 7. It is a top view of the semiconductor light-emitting device which shows other embodiment of this invention. It is sectional drawing of the semiconductor light-emitting device which shows other embodiment of this invention. It is sectional drawing of the semiconductor light-emitting device which shows other embodiment of this invention. It is sectional drawing which shows the semiconductor light-emitting device of a prior art.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 and FIG. 2 are a cross-sectional view and a plan view of a surface-mounted LED shown as an example of the semiconductor light emitting device of the present invention.

  The semiconductor light emitting device has a substrate 1 on which terminals (not shown) for electrical connection with external wiring are formed. On the substrate 1, four elements 2 having different emission colors are provided. The four different emission colors are red, blue, green and white. The element 2 includes a light emitting diode element (hereinafter also referred to as “LED chip”).

  On the surface of the substrate 1, pattern wiring for electrically connecting the electrodes and terminals (not shown) of the respective elements 2 is formed, and the LED chip 2 is mounted thereon. That is, the LED chip 2 is electrically and mechanically connected to the substrate 1 by the Ag paste 5 and the gold wire 6.

  In FIG. 2, i is a white light-emitting part, j is a blue light-emitting part, k is a red light-emitting part, and l is a green light-emitting part (Note that i, j, k, and l are the same in the following drawings. is there).

  Each element 2 is covered with a resin 7. A portion other than the white light emitting portion i is sealed with a transparent or milky white epoxy or silicon resin 7. A blue or ultraviolet LED 2 is mounted on the white light emitting portion i, and is sealed with epoxy or silicon resin 8 containing phosphor.

  The surface shape of each of the resins 7 and 8 can be a convex lens shape or a concave lens shape on the basis of a substantially flat shape.

  Further, by making the gold wire 6 a reverse wire, in particular, the height of the epoxy or silicon resin 8 containing the phosphor can be suppressed, the amount of the resin used and the phosphor contained can be reduced appropriately, and efficient white light emission. Is obtained. Here, as shown in FIG. 1 of Japanese Patent Application Laid-Open No. 2000-049384, the reverse wire is a first bond for forming a gold ball as the substrate 1 side, and a second bond for performing wedge bonding with a low height as an LED. This is a bonding method for the chip 2 side.

  Note that the LED chip 2 can be bonded to the substrate pattern portion with its alloy without using the Ag paste 5 by using an LED element having AuSn or Sn electrode mounted on the back electrode. This is particularly effective when ensuring the bonding strength and efficiently releasing the heat from the LED chip 2 to the lower surface.

  A reflector 9 is provided so as to surround the resin 7 and 8. The reflector 9 has a reflecting surface 10. The reflective surface 10 of the reflector 9 is subjected to metal vapor deposition or plating.

The reflector 9 is formed so as to surround each of the four elements 2.
That is, the reflector 9 is formed for each color, and the reflecting surface 10 is formed at an effective angle for each. By providing the reflectors 9 respectively, the distance between the four elements 2 and the reflecting surface 10 can be set optimally, light can be efficiently taken out to the front surface, and irradiation at a specified distance can be performed. Each surface is efficiently irradiated with each light, and color mixing is also possible easily.

  The reflective surface 10 can be made of a white resin having a high reflectance, but the reflectance can be further increased by increasing the reflectance by depositing or plating a metal. In addition, when it is desired to further increase the color mixing property other than the specified distance, it is also effective to make the reflecting surface 10 between the colors lower than the outer reflecting surface.

  3 and 4 show another embodiment of the present invention, and the reflector 9 is formed so as to surround red, blue and green as a group and to surround white as a group.

  This embodiment is based on that of FIG. 1 and FIG. 2 and differs from the above embodiment in that white light emission and RGB light emission of red, blue, and green are formed by separate reflectors 9. It is different.

  In this embodiment, since RGB is an integral type, the distance from each element 2 to the reflecting surface 10 is different, so the optical axis is slightly shifted when light is extracted to the front surface, and the efficiency of each is reduced. However, the color mixing property is remarkably improved especially when the LED is directly viewed and other than the irradiated surface at the specified distance. Further, the product size can be reduced as compared with the embodiment of FIGS.

  In the present semiconductor light emitting device, first, the white LED chip 2 is allowed to emit light until a predetermined luminance is obtained, and the luminance of the red, green, and blue LED chips 2 is adjusted so as to obtain a predetermined color tone. By doing so, it is possible to obtain a semiconductor light emitting device having high luminance and excellent color rendering.

  FIG. 5 and FIG. 6 show another embodiment of the present invention, and the reflector 9 is formed so as to surround all the colors of red, blue, green and white as a group.

  This embodiment is an example of a surface mount type LED, and white, red, blue, and green light emission are all formed by a single reflector 9 based on the LED of FIG.

  Since all of the features of this device are integrated, the distance from each element 2 to the reflecting surface 10 is different, so the optical axis is slightly shifted when light is extracted to the front surface, and each efficiency is Although it will fall off, especially the color mixing property is remarkably improved even when the LED is not directly viewed and other than the irradiation surface of the specified distance.

  3 differs from that shown in FIG. 3 in that it is an integrated type including white, so that it also has an effect of making the light emission unevenness (non-color mixing) of the RGB light emitting portion inconspicuous at the time of white light emission. Further, the product size can be further reduced as compared with the embodiment of FIG.

  In this figure, the phosphor-containing epoxy or silicon resin 8 is covered with the epoxy or silicon resin 7, but it is also possible to make them individually in the reflector 9.

  7 and 8 show another embodiment of the present invention. The substrate 1 has a mounting surface 11 on which the element 2 is mounted, and the mounting surface 11 has a two-stage structure. Has been. The white element 2 is placed on a different stage from the other color elements 2. In this embodiment, the white element 2 is arranged in the lower stage, and the other color elements 2 are arranged in the upper stage.

Moreover, it is desirable that the type in which all the books are integrated is a type as shown in FIG.
That is, the substrate 1 has a two-stage structure, the blue or ultraviolet LED chip 2 is mounted on the lower stage, and is sealed with a phosphor-containing epoxy or silicon resin 8. The remaining RGB elements 2 are mounted on the upper stage of the substrate 1.

  With this structure, the phosphor-containing epoxy or silicon resin 8 can be easily sealed by a potting method, the shape is stabilized, and the other elements 2 are sealed with a transparent or milky white epoxy or silicon resin 7. In this case, the work can be easily performed.

  In addition, since the phosphor-containing epoxy or silicon resin 8 is hidden in the lower stage, it is possible to efficiently extract light without being shaded when RGB light is emitted.

The elements of “blue and green” and “red and white” can be mounted on different stages.
FIG. 9 shows another embodiment of the present invention. Among the elements 2, white is arranged at the center of the substrate 1, and red, blue, and green elements surround the white element 2. 2 is arranged.

  In this embodiment, when more importance is attached to color mixing, it is desirable to arrange white in the middle and arrange red, blue and green at the positions of the vertices of substantially equilateral triangles.

In this method, it is effective to arrange the red LED chip 2 in the lower stage.
The height of the blue and green LED chip 2 is about 100 μm, but the height of the red LED chip 2 is as high as about 300 μm, and when arranged on the same stage, it may become a shadow when emitting blue and green, It becomes a factor which reduces luminous efficiency. By arranging the red LED chip 2 in the lower stage, this problem can be solved and an efficient light emitting device can be provided. That is, it is possible to increase the luminance by disposing the high-height LED chip in the lower stage so as not to disturb the optical path of light from the low-height LED chip.

  In addition, about the height of a lower stage part, it is desirable that it is the height which the element 2 of the white light emission part i can seal reliably, and is lower than the height of the light emitting layer of the red LED chip 2. FIG. This method is also effective when green light emission is performed by phosphor excitation.

  In all the embodiments described above, it is of course possible to mount the substrate 1 in two stages and mount all the chips 2 in the lower stage as shown in FIG. Although the product size is slightly increased, the resin sealing operation is easy and stable, and the manufacturing process is simplified.

  Further, as shown in FIG. 11, the substrate 1 is made up of three stages, the necessary combinations of elements 2 are arranged in the lower stage and the middle stage, and the third stage is formed as a sealing resin dam. Further, the resin sealing operation can be facilitated and stabilized, and the manufacturing process can be simplified.

  In addition, the said embodiment disclosed this time is an illustration in all the points, Comprising: It is not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and includes all modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be used in the semiconductor light emitting device industry.

  1 substrate, 2 elements (LED chip), 9 reflector, 10 reflecting surface, 11 mounting surface.

Claims (2)

A substrate,
Provided with four light emitting portions provided on the substrate, each having red, blue, green, and white light emission colors different from each other;
In the light emitting part, different LED chips are individually covered with resin,
A semiconductor light-emitting device, wherein a reflector is formed so as to surround the four light-emitting portions as a group.   The semiconductor light-emitting device according to claim 1, wherein metal deposition or plating is performed on a reflection surface of the reflector.

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