JP2011171345A - Light emitting device and method of manufacturing the same - Google Patents

Abstract

By improving the amount of light reflected by the peripheral wall of the light emitting device, the amount of light emitted in the direction facing the LED mounting surface of the light emitting device can be increased and the color temperature characteristics can be improved, and the size and processing can be reduced. Provided are a light emitting device and a method for manufacturing the same.
A substrate having an electrode, a light emitting element mounted on the substrate, a peripheral wall body provided on a light emitting element mounting surface of the substrate, and defining a cavity for housing the light emitting element together with the substrate. The peripheral wall body is formed of a resin in which particles having light reflectivity are dispersed.
[Selection] Figure 1

Description

  The present invention relates to a light emitting device and a manufacturing method thereof, and more particularly to a light emitting device having a light emitting diode (LED) and a manufacturing method thereof.

  Conventionally, a light emitting device obtained by processing a printed circuit board has been manufactured from the viewpoint of good processability and cost. In such a light emitting device, a glass epoxy substrate having good heat resistance and low thermal expansion is used because it is exposed to a temperature of about 260 ° C. instantaneously in solder mounting. In a conventional light emitting device, light (radiation) radiated in a direction opposite to the substrate surface on which the LED element is mounted on a substrate on which a circuit (electrode pattern layer) is formed on the front and back surfaces of the substrate using through holes or the like. In order to improve the light extraction efficiency, a light emitting device having a peripheral wall has been manufactured by bonding a substrate having an opening cut into a circle or a rectangle and cutting the substrate into a matrix.

  As a conventional light-emitting device having such a peripheral wall body, a light-emitting device using a LED element as a light-emitting body and having a peripheral wall body made of a resin and a metal reflective layer formed on the resin surface is known. (Patent Document 1).

  There is also known a light emitting device using a glass epoxy substrate formed by impregnating a peripheral wall with a resin containing reflective particles in a glass woven fabric using an LED element.

JP 2001-144333 A

  However, in a light emitting device having a peripheral wall with a metal reflective layer, when the light emitting device is downsized, insulation between the metal reflective film and the wiring on the substrate surface on which the LED element is mounted is ensured. This makes it difficult to reduce the size of the light emitting device. In addition, there are problems such as peeling at the interface between the metal reflective film and the sealing resin injected into the cavity surrounded by the peripheral wall, or cracks in the sealing resin due to temperature changes, and the bonding wire is cut. Or the production yield deteriorated.

  Further, in the light emitting device having a peripheral wall made of a glass epoxy substrate, light is leaked to the outside by being guided in a direction parallel to the substrate through the glass fiber exposed to the side of the peripheral wall, There exists a problem that the extraction efficiency of the light radiated | emitted in the direction facing the surface where the LED element of the light-emitting device is mounted will fall. This light leakage becomes more prominent as the thickness of the peripheral wall portion of the cavity structure is reduced in order to reduce the size of the light emitting device, which has been an obstacle to downsizing of the light emitting device. Further, in the manufacture of a light emitting device having such a peripheral wall body, it is necessary to cut strong glass fibers at the time of dicing, and the cutting of the glass fibers has been a factor of reducing workability at the time of manufacture. .

  The present invention has been made in view of the above-described points, and an object thereof is to provide a light-emitting device with high light extraction efficiency. It is another object of the present invention to provide a light-emitting device that can be easily downsized and can improve processability and yield during manufacturing, and a method for manufacturing the light-emitting device.

  A light-emitting device of the present invention includes a substrate having an electrode, a light-emitting element mounted on the substrate, and a peripheral wall body that is provided on the light-emitting element mounting surface of the substrate and defines a cavity that accommodates the light-emitting element together with the substrate. And the peripheral wall body is formed of a resin in which particles having light reflectivity are dispersed.

  The method of manufacturing the light emitting device of the present invention includes a step of providing a cavity structure that forms a cavity together with an LED element mounting surface of a substrate on a substrate on which an electrode is formed, and a substrate surface exposed in the cavity. Mounting the light emitting element, wherein the cavity structure is formed of a resin in which particles having light reflectivity are dispersed.

  According to the light emitting device and the method for manufacturing the light emitting device of the present invention, it is possible to increase the amount of light emitted in the direction facing the LED mounting surface of the light emitting device by improving the amount of light reflected by the peripheral wall of the light emitting device. . In addition, a light emitting device that can be easily downsized and processed can be realized.

It is sectional drawing of the light-emitting device of Example 1 of this invention. It is a top view of the light-emitting device of Example 1 of this invention. It is sectional drawing of the manufacture process of the light-emitting device of Example 1 of this invention. It is a top view of 1 process of the manufacturing process of the light-emitting device of Example 1 of this invention. It is sectional drawing of the light-emitting device of a comparative example.

  FIG. 1 is a cross-sectional view of a light emitting device using the LED element of Example 1 of the present invention as a light emitting element, and FIG. 2 is a plan view seen from the light emitting surface of the light emitting device of Example 1 of the present invention. is there. 1 is a cross-sectional view taken along line AA in FIG.

  As shown in FIGS. 1 and 2, the light emitting device 10 includes a substrate 11, an electrode 12, an LED element 13, a peripheral wall body 14 </ b> A, and a sealing resin 15. An electrode 12 is formed on the substrate 11, and the LED element 13 is mounted on the substrate 11 by die bonding, and is electrically connected to the electrode 12 by a bonding wire 16. 14 A of surrounding wall bodies are provided on the board | substrate 11, and the cavity (recessed part) 17 which exposes the LED element 13 by the surrounding wall body 14A and the board | substrate 11 is demarcated (FIG. 3), and the sealing resin 15 is filled into the cavity 17 ing.

  The substrate 11 is a glass epoxy substrate having a thickness of 0.1 mm, and has a plurality of through holes. The glass epoxy substrate is configured by impregnating an epoxy resin into a glass woven fabric in which glass fibers are knitted into a cloth shape. The electrode 12 is formed on the substrate 11, and the mounting surface of the LED element 13 is formed of Cu foil / Cu plating / Ni plating / Ag plating. Also, Cu foil / Cu plating / Ni plating / Ag plating / Au plating is formed on the surface opposite to the mounting surface of the LED element 13, and Cu plating is formed in the through hole.

  The LED element 13 is fixedly placed at a predetermined position on the substrate 11 with a resin adhesive, solder, or the like. The LED element 13 is, for example, a blue LED element. The LED element 13 is connected to the electrode 12 on the substrate 11 by a bonding wire 16.

  The peripheral wall body 14A is fixed on the substrate 11 with an epoxy adhesive such that the cavity 17 exposes the LED element 13. As will be described later, the peripheral wall body 14A is formed of an epoxy resin in which light-reflective particles are dispersed.

  The sealing resin 15 is provided so as to embed the LED element 13 in the cavity 17 defined by the peripheral wall body 14 </ b> A and the substrate 11. The sealing resin 15 is made of an organically modified silicone cured resin in which a YAG (yttrium, aluminum, garnet) phosphor is dispersed. The sealing resin 15 may be another light-transmitting resin such as an epoxy resin or a urethane resin, and may contain a phosphor other than the YAG phosphor or a scattering material.

  Next, with reference to FIG. 3 and FIG. 4, the manufacturing method of the light-emitting device 10 shown in FIG.1 and FIG.2 is demonstrated in detail. FIGS. 3A to 3D are cross-sectional views illustrating steps of the method for manufacturing the light emitting device 10. FIG. 4 is a plan view showing one step (FIG. 3B) of the manufacturing method. That is, FIG. 3B is a cross-sectional view taken along line BB in FIG.

  In the manufacture of the light emitting device 10, first, as shown in FIG. 3A, a flat glass epoxy substrate 11 having an electrode 12 formed on the surface is prepared, and a flat cavity structure 14 having an opening. Was bonded onto the substrate 11 with an adhesive (not shown). The cavity structure 14 is a frame formed of an epoxy resin in which light reflective particles made of titanium oxide, barium sulfate particles, or the like are dispersed. In addition, glass particles for suppressing thermal expansion are also dispersed in the epoxy resin. Note that glass fiber (fibrous glass) is not mixed in the peripheral wall body 14A. Moreover, what mixed the titanium oxide etc. in the epoxy resin was used for the adhesive agent. In addition, it is preferable from a reflective viewpoint that the light-reflective particles are uniformly dispersed. More specifically, the cavity structure 14 includes a peripheral wall body 14A that forms, together with the substrate 11, a cavity 17 having a rectangular shape with a long side length L1 of 1.8 mm and a short side length L2 of 1.4 mm. It is a frame. The thickness H1 in the direction perpendicular to the surface on which the LED element 13 of the cavity structure 14 is mounted is 0.4 mm. In this embodiment, the cavities 17 are arranged in a matrix (3 rows and 3 columns in the figure). As shown in FIG. 4, the wall portion forming the peripheral wall body 14 </ b> A surrounding the cavity has a thickness W <b> 1 at the outermost part of the cavity structure 14 of 0.1 mm, and the thickness between the cavities 17. W2 is 0.3 mm.

  Next, as shown in FIG. 3 (b), a blue LED element 13 having a side length of 0.9 mm and a thickness of 170 μm is formed on the exposed substrate 11 in the cavity 17 with respect to one cavity 17. One was placed using a collet and die bonded, and was electrically connected by wire bonding using the LED element 13, the electrode 12 and the bonding wire 16. In the cavity 17, two or more LED elements may be arranged.

Next, as shown in FIG. 3C, a sealing resin 15 containing a phosphor was filled in the cavity 17 by a dispensing method or the like so that the LED element 13 was embedded. Next, the entire substrate was put into a furnace at 150 ° C. and heated for 5 hours to cure the sealing resin 15. The sealing resin 15 is an organically modified silicone resin containing a YAG phosphor, and the ratio of the YAG phosphor to the organically modified silicone was 22 wt%. The sealing resin 15 may be made of another light transmissive resin such as an epoxy resin or a urethane resin, and the light transmissive resin contains a phosphor other than the YAG phosphor or a scattering material. May be. Moreover, it is preferable that the sealing resin 15 has a Shore A hardness of 70 or more after curing or a Shore D hardness of 50 or more after curing.
Finally, as shown in FIG. 3D, the substrate on which the LED elements 13 were mounted was cut into a predetermined size. As a cutting method, a normal dicing method was used. FIG. 2 is a top view of the completed light emitting device 10 as viewed from the light emitting surface. As for the dimensions of the completed light emitting device 10, the long side L3 was 2.0 mm, the short side L4 was 1.6 mm, and the thickness H2 including the thicknesses of the electrodes and the adhesive was 0.7 mm.

  A comparative light-emitting device 20 formed to confirm the effect of the light-emitting device 10 of the present invention will be described below. The light emitting device 20 of the comparative example is a peripheral wall formed by impregnating a glass woven fabric with a resin containing reflective particles as shown in FIG. 5 without using the cavity structure of Example 1 of the present invention. Except for the point of using the body 21, it was the same as the above-described example. The peripheral wall 21 has a glass woven fabric layer 21A and a reflective particle-containing resin layer 21B.

  That is, in the light emitting device 20 of the comparative example, a peripheral wall body 21 in which a glass woven fabric is impregnated with a resin containing titanium oxide particles, barium sulfate particles, and the like on a glass epoxy substrate having an electrode for supplying power to the LED elements. The peripheral wall body 21 has a glass woven fabric layer 21A and a reflective particle-containing resin layer 21B. The other points such as the shape and size of the peripheral wall body are the same as those in the first embodiment. In addition, the LED element having the same structure and characteristics as used in Example 1 is die-bonded at the same position as in Example 1, and the inside of the cavity is made of the same material as in Example 1 The LED element is filled so as to be embedded. In addition, the phosphor amount in the sealing resin of the light emitting devices of Example 1 and Comparative Example was 22 wt%.

  In addition, it confirmed that there was no significant difference in the reflectance of the reflective particle containing resin layer of the surrounding wall body of the light-emitting device 10 of Example 1, and the surrounding wall body 22 of the light-emitting device 20 of a comparative example. That is, the reflectance of the peripheral wall body 14A parallel to the LED element mounting surface of the substrate and the main surface of the peripheral wall body 21 (the reflective particle-containing resin layer 21B) has no significant difference in the wavelength range between 400 nm and 700 nm. This was confirmed by measurement.

  Table 1 shows a comparison result when the light emitting devices of Example 1 and the comparative example were caused to emit light. In addition, each LED element of Example 1 and a comparative example was driven with the drive current from which the light emission luminance of an LED element becomes the same. In addition, it measured about 20 samples and has shown by the average value.

  Table 1 shows the luminous intensity (candela, cd), correlated color temperature (Kelvin, K), and total luminous flux (lumen, lm) from the radiation surface (element mounting surface) of the light emitting devices of Example 1 and Comparative Example. Shown in comparison.

  As shown in Table 1, the luminous intensity (IE) and the total luminous flux (LE) of the light emitting device of Example 1 are 1.07 times (that is, 7%) compared with the luminous intensity (IC) and the total luminous flux (TC) of the comparative example. Increase). In the light emitting device of the comparative example, since the emitted light from the LED element is lost by being guided in the lateral direction (direction parallel to the radiation surface) by the glass woven fabric layer 21A, the luminous intensity and the total luminous flux are small. Further, the light emitting device of Example 1 emitted light with a stronger yellow color than the light emitting device of the comparative example. This means that in Example 1, the LED radiation component reflected by the peripheral wall is increasing. In other words, since the reflection component by the peripheral wall further passes through the sealing resin and is emitted from the radiation surface, it means that the light path length in the sealing resin is long and the yellowish light component is increasing. is doing.

  Therefore, the color temperature of the light emitting device of the comparative example was adjusted to the same color temperature as in Example 1 by increasing the amount of the YAG phosphor contained in the sealing resin of the comparative example, and again the comparative experiment. Went. The experimental results are shown in Table 2.

  Table 2 compares the phosphor concentration (wt%, wt%) in the sealing resin of the light emitting device of Example 1 and the comparative example, and the luminous intensity (cd) of the emitted light from the emitting surface (element mounting surface). ing. Correlated color temperature (K) is also shown for reference.

  As shown in Table 2, the light emitting device of Example 1 can reduce the amount of phosphor for obtaining the same color temperature by about 8% and about 5% compared to the light emitting device of the comparative example. An increase in luminous intensity could be achieved.

  In the light emitting device of the present invention, the peripheral wall body for reflecting the light emitted from the LED element is formed of a resin in which light reflecting particles are dispersed. Accordingly, it is possible to realize a light-emitting device with higher insulation and higher yield than conventional light-emitting devices. In addition, since light lost through the peripheral wall body can be reduced, the light emission efficiency of the light emitting device can be increased as compared with the conventional light emitting device. Moreover, since the ratio of the amount of light having a long optical path length in the sealing resin containing the phosphor reflected by the peripheral wall body increases, the emission color (color temperature) can be adjusted with less phosphor than the conventional light emitting device. Is possible. Furthermore, in the manufacture of the light emitting device of the present invention, since a cavity structure made of a resin in which light reflecting particles are dispersed is used, processing can be performed with high precision and is easy. For example, unlike a conventional light emitting device using a glass woven fabric, it is not necessary to cut a strong glass fiber during cavity formation or dicing.

  In the first embodiment, a glass epoxy substrate is used as the substrate 11, but another resin substrate, a ceramic substrate, or the like may be used. Further, in the first embodiment, the wire connection is used for the electrical connection between the LED element 13 and the electrode 12, but a bump may be provided on the back surface of the LED element 13 to perform the flip chip connection. Further, the emission wavelength of the LED element 13 is not limited to the wavelength described in the above embodiment. In this case, a material or the like of the light reflecting particles may be appropriately selected so that a suitable light reflectance can be obtained according to the emission wavelength of the light emitting element. Moreover, although the shape of the cavity is a rectangle, it can be an arbitrary shape such as a circle. Moreover, in the said Example, although the case where nine light-emitting devices of 3 rows and 3 columns were manufactured from one board | substrate was shown as an example, it is not restricted to this. Furthermore, various numerical values, dimensions, materials, and the like in the above-described embodiments are merely examples, and can be appropriately selected according to the light-emitting element used.

DESCRIPTION OF SYMBOLS 10 Light-emitting device 11 Substrate 12 Electrode 13 LED element 14 Cavity structure 14A Perimeter wall 15 Sealing resin 16 Bonding wire 17 Cavity 20 Light-emitting device 21 of comparative example Peripheral wall 21A of comparative example Glass woven fabric layer 21B Reflective particle-containing resin layer

Claims (6)

A substrate having electrodes;
A light emitting device mounted on the substrate;
A peripheral wall provided on a light emitting element mounting surface of the substrate, and defining a cavity for housing the light emitting element together with the substrate;
The light emitting device, wherein the peripheral wall body is formed of a resin in which particles having light reflectivity are dispersed.   The light emitting device according to claim 1, wherein the substrate is made of a glass epoxy substrate obtained by impregnating a glass woven fabric with an epoxy resin, and the peripheral wall is made of an epoxy resin in which glass particles are dispersed. .   The light-emitting device according to claim 1, wherein the translucent resin contains phosphor particles.   The light-emitting device according to claim 1, wherein the resin forming the peripheral wall further contains glass particles. A method for manufacturing a light emitting device, comprising:
Providing a substrate on which an electrode is formed with a cavity structure that forms a cavity together with an LED element mounting surface of the substrate;
Mounting a light emitting element on a substrate surface exposed in the cavity, and
The method is characterized in that the cavity structure is formed of a resin in which particles having light reflectivity are dispersed.   The substrate is composed of a glass epoxy substrate obtained by impregnating a glass woven fabric with an epoxy resin, the cavity structure is composed of an epoxy resin in which glass particles are dispersed, and in the step of providing the cavity structure, The method of claim 5, wherein the cavity structure is bonded through an adhesive.

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