JP2007329444A - Light emitting element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin light emitting element with high light directivity, light use efficiency and efficient productivity. <P>SOLUTION: This light emitting element includes a concave section formed in a metallic layer on a circuit board; a light emitting diode chip installed in the concave section; and a light extractor configured of light transmissive resin materials formed so that at least the concave section can be packed, and the light emitting diode chip can be covered. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a novel light-emitting element with high light utilization efficiency, in particular, a narrow directivity mounting type (SMD) light-emitting diode (LED) lamp, and a novel manufacturing method thereof. The method of the present invention improves the performance of the LED lamp while maintaining a small and thin shape characteristic, and also provides manufacturing advantages such as an improvement in yield and productivity and a reduction in cost.

  Examples of prior art relating to narrowly directional mounted LED lamps are shown in FIGS. 1a, 1b, 2a, 2b, 2c and 2d. FIGS. 1a and 1b show a technique for bonding two PCB layers (10 and 20) (conventional example 1). FIGS. 2a, 2b, 2c and 2d show a translucent molded product 33 and light reflection on a substrate. This is a technique (Conventional Example 2) for sequentially forming the molded product 34 (see Patent Document 1). In Conventional Example 1, as shown in FIGS. 1a and 1b, after a large number of chips 11 are integrated and mounted on the circuit board 10, it is necessary to provide a reflector to increase the light utilization rate of each element (chip). In order to install the reflector, a through hole 21 is formed in another circuit board (second layer board) 20 and bonded to the circuit board (first layer board) 10 on which the chip is mounted. Had to be formed. On the other hand, in the conventional example 2 shown in FIGS. 2a, 2b, 2c, and 2d, the circuit board 30 is entirely covered (FIG. 2a) or is a certain size island-shaped (FIG. 2b) molded product (primary molding). After forming the object 32 or 33), the primary molding had to be partially removed by dicing, the second reflective material was molded into this structure and the reflector 34 had to be installed.

  Furthermore, in the conventional example 1, since the two circuit boards are combined, the cost of the circuit board and the yield / productivity of the light emitting diodes are reduced. In the conventional example 2, the epoxy resin is cured. At this time, the shrinkage rate of the molded product is different from that at the time of temperature change of the circuit board, and is usually about 0.5% to 1.5%. Therefore, the shrinkage force of the molding resin is transmitted to the circuit board to be deformed. And the curve becomes intense. In this case, in order to keep the thickness of the circuit board and the thickness of the metal board constant at the target values, it is necessary to accept the bending of the circuit board, but at that time, due to the bending of the center and both sides of the board If the height difference is about 0.5 mm or more, it becomes difficult to form the reflective material in a predetermined shape by dicing, which may adversely affect the yield and productivity of the light emitting diode. In this case, there is a possibility that problems such as separation of the formed resin from the light emitting diode and separation of the light emitting diode due to the large shrinkage force contained in the molded resin. Furthermore, in order to mold the reflecting plate, it is necessary to form a reflecting structure by dicing.At that time, if the degree of dicing is increased, insufficient adhesion between the resin and the circuit board used for the reflecting plate occurs. Peeling from the manufactured light emitting diode may occur. For this reason, normally dicing must be performed conservatively, but this may cause a problem that light is not reflected through the gap and light leaks.

  Further, in Conventional Example 2, by mounting the light emitting diode chip on the circuit board plane, the emitted light from the chip should be reflected by the thin light reflector and have directivity. From the viewpoint of reflection efficiency, light directivity, and other light utilization efficiency, the overall performance is reduced as compared with the case where the reflection structure is installed on the circuit board. Further, when the emitted light advances while being repeatedly reflected by a thin light reflecting plate, the reflecting plate is cured and absorbs the emitted light, and the reliability of the light emitting diode is lowered.

Moreover, the light reflector installed after dicing in Conventional Example 2 must be installed from the circuit board in order to prevent light leakage, and is therefore manufactured at approximately the same height as the optical lens portion of the primary molded product. Therefore, if the physical properties such as the thermal expansion coefficient are not similar, there will be a problem of peeling of the molded product during the reflow process, resulting in many problems such as peeling of the lens part, wire breakage, peeling of the reflector, etc. there is a possibility.
Patent Document 2 relates to a general method for manufacturing a light-emitting diode, and Patent Document 3 relates to a light-emitting diode that can effectively use light from the lower surface of an LED chip.
JP 2002-368281 A JP 2002-368286 A JP 2005-56941 A

  The present invention is a reduction in yield / productivity due to tolerance management caused by the technology of joining two conventional circuit boards, peeling due to the installation of a reflector by dicing and secondary molding, a reduction in light utilization efficiency, etc. In the solution of this problem, especially in the miniaturization and slimming down of the light emitting diode, the conventional technology coated the metal plate with an epoxy-based material in order to solve the peeling problem, but this caused a loss of light utilization efficiency, The purpose is to eliminate various limitations in reducing the reflection efficiency of the light reflection plate, separating the light reflection plate from the lens portion, scattering light, and slimming the light reflection plate.

In order to solve the above problems in the prior art, the present invention has the following features. That is, the present invention relates to a recess formed in a metal layer on a circuit board, a light emitting diode chip installed in the recess, and a light transmitting property formed so as to fill at least the recess and cover the light emitting diode chip. The present invention relates to a light emitting element including a light extraction portion made of a resin material.
The present invention also relates to the above light emitting device, wherein the concave portion is formed by half etching.
The present invention further relates to the light-emitting element, wherein the horizontal sectional area of the recess is smaller as it is closer to the circuit board.
The present invention still further relates to the light emitting device, wherein the recess is coated with a highly reflective substance.
The present invention also relates to the light-emitting element, wherein the highly reflective substance is a metal selected from the group consisting of Ag, Al, and Au.
Furthermore, this invention relates to the said light emitting element in which the light extraction part is formed with the resin material or silicone material whose refractive index is lower than a light emitting diode chip.
Furthermore, this invention relates to the said light emitting element in which the part in which a recessed part is located among the light extraction parts is formed thickly compared with the other part.

The present invention also relates to the above light emitting element, further including a light guide portion formed above the circuit board so as to surround the recess and having at least an inner side made of a highly reflective material.
The present invention further relates to the light emitting device, wherein the light guide portion is made of a resin material.
Furthermore, the present invention relates to the light emitting element, wherein the light guide portion is formed to have a predetermined inclination.
The present invention also relates to the light emitting element, wherein the light guide part is formed on the light extraction part.
Furthermore, this invention relates to the said light emitting element in which the light guide part is formed in the predetermined distance from the circuit board.
Furthermore, the present invention relates to the light emitting element, further including a lens portion made of a light transmissive material on the light extraction portion.
The present invention also relates to the above light emitting device, wherein the light transmissive material includes one or more additives selected from phosphors and diffusing agents.
The present invention further relates to the above light emitting device, wherein the lens portion is made of a film.
The present invention still further relates to the above light emitting device, further comprising a through path connecting the metal layer of the circuit board and the electrode and / or metal plate under the circuit board.

Also, the present invention provides a first step of forming a recess in a metal layer on a circuit board, a second step of mounting a light emitting diode chip in the recess, and filling at least the recess to cover the light emitting diode chip. A third step of forming a light extraction portion with a light transmissive resin material, a fourth step of forming a light guide portion by molding a light reflective resin material so as to surround the recess above the circuit board, and The present invention also relates to a method for manufacturing a light emitting element, including a fifth step of forming a lens portion by molding a light transmissive material in a space surrounded by a light guide portion.
Furthermore, the present invention provides a first step of forming a recess in the metal layer on the circuit board, a second step of mounting the light emitting diode chip in the recess, filling at least the recess and covering the light emitting diode chip. A third step of forming a light extraction portion with a light transmissive resin material, a fourth step of forming a light transmissive material on the extraction portion to form a lens portion, and at least on the side of the lens portion, The present invention relates to a method for manufacturing a light emitting element, including a fifth step of forming a light guide portion by molding a light reflective resin material so as to surround a recess.

Furthermore, the present invention provides a process for mounting a light-emitting diode chip on a circuit board, and surrounds the side of the light-emitting diode chip, and the horizontal cross-sectional area of the enclosed space becomes smaller as the circuit board is closer. The present invention relates to a method for manufacturing a light-emitting diode, comprising: forming a light guide part by molding a light-reflective resin material; and forming a lens part by molding a light-transmitting material in the enclosed space. .
The present invention also relates to the method, further comprising the step of forming a reflective structure by providing a recess in the metal layer on the circuit board.
The present invention further relates to the method, further comprising forming a reflective structure on the circuit board by bonding another circuit board having an opening corresponding to the position of the light emitting diode chip.

In the present invention, by using plating and wet etching techniques, it is possible to precisely install the light reflecting structure (recessed portion) in one circuit board, and the yield and productivity are increased, and the performance is also improved. To do. In particular, when the reflective structure is coated with a metal having a high reflectance, the light utilization efficiency is increased. Also, it is possible to form a small extractor with a small thickness, improve the light extraction efficiency, and improve the light utilization efficiency for other purposes such as wavelength conversion and diffusion. is there.
In addition, the present invention has improved uniformity, yield and mass productivity, reduced cost, large-sized chips and multiple chips, even in the case of small-scale production, as compared to the conventional method using the Japan-Nichia dispensing method. It is possible to manage tablets for phosphors and diffusers for mounting and molding compounds, improve heat release characteristics, and reduce the size and slimness, especially the light output performance.
Furthermore, according to the present invention, it is possible to solve the problem of peeling due to the bending of the circuit board, which has been a problem when using the conventional circuit board, and to improve the yield and productivity and reduce the cost compared to the case where the double circuit board is used. Therefore, it is possible to reduce the manufacturing unit cost associated with the improvement of the light utilization efficiency and the light performance by installing the reflecting structure.

The present invention is one aspect thereof.
A first step of creating a reflector and a reflecting structure (concave) on the circuit board;
A second step in which after the light emitting diode chip is mounted on the circuit board and integrated, the light extraction unit is individually primary molded with a transparent resin material;
A third step of secondarily molding the light guide portion with a light-reflective resin material between the molding structures formed by the second step;
A fourth process for producing a lens part by filling a mixture in which various additives such as phosphors are mixed with a transparent material between the molded structures formed by the third process, and a fifth process for separating a light emitting diode. A method for manufacturing a light-emitting diode including the above will be described below as an example.

  In the first step of the present invention, in order to improve directivity and output characteristics, a metal such as Cu plated on the circuit board is half-etched and then a highly reflective material such as Ag, Al, Au, etc. It can be coated by re-plating a metal such as. The thickness of the metal layer (such as Cu plating) on the circuit board is not particularly limited as long as the reflective structure can be sufficiently formed, but is preferably 80 to 300 μm, more preferably 120 to 220 μm, and particularly preferably 150 to 200 μm. It is. The high reflectance is not particularly limited as long as the light utilization rate is improved, but is preferably about 70% or more, more preferably about 80% or more, and particularly preferably about 90% or more. At this time, the shape of the etched reflection structure has a plurality of radii of curvature, for example, it is formed in a tapered shape, a dish shape, or a bowl shape so that the horizontal sectional area of the reflection structure becomes smaller as it is closer to the circuit board. If the reflection of the light toward the side surface and the lower surface can be induced, the efficiency is improved. In particular, it is effective to have a narrow directivity.

In the second step of the present invention, an extraction part (light extraction part) that extracts and passes light and a guide part (light guide part or reflection part) that imparts narrow directivity using light reflection and guidance characteristics are formed. In order to care for light emitting diode chips and wires, and to increase the light extraction efficiency, the extraction part molding is usually made of a resin material or silicone material that is transparent and has a lower refractive index than the semiconductor. Molded before the guide.
In the second step of the present invention, the extraction unit can be molded individually for each chip. Furthermore, in order to increase the number of contraction centers as much as the number of chips to be integrated to prevent the circuit board from being bent, the whole is thinned, and a portion where the chip is located, for example, a recess is located. A method of thickening only the part can also be used.
Through the above steps, a recess formed in the metal layer on the circuit board, a light emitting diode chip mounted on the recess, and a light-transmitting resin formed to fill at least the recess and cover the light emitting diode chip A prototype of the light emitting device of the present invention including a light extraction portion made of a material is completed.

In the third step of the present invention, in order to produce a guide portion that imparts directivity to light, a material having a high reflectance, such as a resin material, is used between the structures of the extraction portion formed in the second step. Next molding can be performed. As a result, the light guide portion is formed so as to surround the recess. The light guide portion does not necessarily have to be reflective as a whole, and at least the inner side, that is, the side facing the chip, may be made of a highly reflective material. Further, at this time, the guide portion has a great effect of giving directivity to the final emitted light, and thus can be positioned on the extraction portion formed in the second step. In particular, it may be located at a certain distance from the circuit board. This distance is not particularly limited as long as it can give good directivity to light, but is preferably 1 to 100 μm, more preferably 2 to 50 μm, and particularly preferably 5 to 15 μm. In this way, by forming the extraction part over the entire area of the circuit board, the occurrence of peeling can be further suppressed, and the transfer molding operation can be facilitated. Become.
In the third step of the present invention, the feature of the shape of the guide portion is that the light emitted from the chip is reflected well and has high directivity, so that it can have a certain inclination (tilt). . This inclination is not particularly limited as long as the above-described effect can be obtained, but it is preferably 0 to 15 °, more preferably 4 to the vertical of the circuit board so that the top of the guide part is farther from the chip than the base. It is 12 °, particularly preferably 6 to 12 °.

In the fourth step of the present invention, in order to improve the light passing efficiency of the light extraction unit formed in the second step, another layer having a different refractive index is used to further increase the extraction efficiency or provide directivity. In this case, various additives such as a phosphor can be mixed with the transmissive resin for the purpose of wavelength conversion or diffusion, if necessary.
In the fourth step of the present invention, the lens portion can be manufactured by filling the space between the molded structures formed in the third step.

  In the first step of the present invention, the metal such as Cu plated on the circuit board, or the metal substrate is used for effective release of heat generated from the chip, and the thickness of the plated Cu is It is very effective for heat transfer, and it is possible to install a heat transfer passage that penetrates the lower electrode and the metal plate with a metal having good thermal conductivity. Here, the thermal conductivity of the metal is not particularly limited as long as good heat transfer is obtained, but is preferably 200 W / m ° K or more, more preferably 300 W / m ° K or more, and particularly preferably 350 W / m ° K. That's it.

  In the present invention, the reflecting structure formed in the first step can be manufactured by joining two circuit boards, or can be produced on a plane and used.

  The present invention can also be performed by switching the order of the third step and the fourth step. Here, if necessary, the lens portion can be formed by adhesion of a film instead of molding.

[Example]
The invention will be further described with reference to FIGS. 3, 4a, 4b, 5, 6, 7, 8, 9 and Table 1. FIG. 3 is an external view of the present invention. FIGS. 4a and 4b and Table 1 show the shape and production data of the Cu reflecting structure formed on the circuit board 100, respectively. FIG. FIGS. 6A and 6B are schematic diagrams illustrating the formation of the extraction unit 120. FIGS. 7 and 8 show a modification of the present invention in which the lens part 140 is produced prior to the guide part 130, and the last FIG. 9 shows the shape of the guide part 130 produced. The thickness of the Cu plating 101, 111, 112 of the circuit board 100 to be used can be about 150 μm or more, which is sufficient to form a reflective structure.

The metal substrate and the upper substrate 100 attached to the lower surface are subjected to etching, cutting by a routing method, installation of a through hole for heat dissipation, and / or plating or filling of a conductive material.
A light reflecting structure (concave portion) is formed using an exposure technique. The shape of the structure has a plurality of radii of curvature so that the downward light and the light directed to the side surface have directivity. The reflective structure is also completed by coating with a metal material such as Ag having a high reflectance. At this time, the size and shape of the reflecting structure are optimized so that re-absorption of light emitted from the chip 160 does not occur (see FIG. 4b and Table 1).

After the diode chip 160 is mounted on the circuit board 100, the light extraction portion must be molded. Usually, in order to prevent re-absorption at the chip 160, the refractive index of the molded product is made smaller than that of the semiconductor chip 160. Separate and install diffuser plates and wavelength-converting white phosphors.
At this time, the circuit board 100 is made of an epoxy resin or a resin so as not to cause a separation problem between chips or in a reflow process due to a difference in thermal expansion coefficient between the material of the molded product and the circuit board 100 and the metal layer 101. It can be coated with materials such as resists.

In order to solve the above problem, the extraction unit 120 also forms and coats each chip 160 individually when molding, or makes the thickness where the part where the light guide unit 130 is installed and the part where the chip 160 is coated differ from each other. The number of contraction centers can be increased. At this time, it is preferable to reduce the thickness of the extraction unit 120 as much as possible and to reduce the shrinkage rate, but this can be achieved by installing the light reflecting structure on the circuit board. Also, the internal contraction force is made as small as possible so that problems such as peeling of the manufactured light emitting diode do not occur.
In order to make light incident on the light guide plate, it is preferable to install a light guide layer (light guide portion). Usually, white or metal molecules are dispersed and the reflectivity is high, or the light guide plate. Use a material with a large difference in refractive index. This layer is installed directly on the circuit board 100 or on the upper layer of the light extraction unit 120. At this time, it is preferable to install the light guide portion so as not to hinder the progress of desired light.

Finally, in order to improve the light efficiency of the lens, a layer having a refractive index different from that of the extraction unit 120 is used, or various additives such as a phosphor are mixed with a transparent resin for the purpose of wavelength conversion and diffusion. Then, after filling the space between the molded structures 130 formed in the third step to form the lens portion, the light emitting diode is separated. Here, the lens portion can be formed by adhering a film instead of molding, if necessary.
In addition, a dicing method can be used to separate the light emitting diodes individually, but the narrowly directional surface-mount LED lamp manufactured in this way is a step by ensuring production uniformity and convenience. Yield, productivity, unit price, and reliability.

Some Variations of the Method of the Invention One variation of the invention is to half-etch the circuit board 100 and integrate and mount the light emitting diode chip 160 on the circuit board without providing a reflector and reflection structure. From the above, after the extraction unit 120 is primary-molded individually for each chip 160 with a transparent resin, or after the guide unit 130 for light directivity is first produced, the efficiency of the lens is finally improved. For surface conversion or light diffusion, various additives such as a transparent resin and a phosphor are mixed to fill the space between the molded structures 130 and separate the light emitting diodes. It relates to a manufacturing method.

The reflection structure in the first step can be manufactured by joining two circuit boards as in the conventional technique, or a reflection structure manufactured on a plane can be used.
It is also possible to produce the third process and the fourth process by changing the order of each other (see FIG. 8).

It is the figure which showed the prior art which manufactures a reflecting plate, after integrating and mounting many chips | tips on a circuit board. It is the figure which showed the prior art which manufactures a reflecting plate, after integrating and mounting many chips | tips on a circuit board. It is the figure which showed the process of mounting a chip | tip on a circuit board. It is the figure which showed the prior art which forms a molded object in the whole circuit board or the island shape of a fixed magnitude | size. It is the figure which showed the prior art which removes a primary shaping | molding part by dicing, shape | molds a 2nd reflective material in this structure, and installs a reflecting plate. It is the figure which showed the shape of the reflective structure and directivity structure which are formed in a circuit board. It is the figure which showed the shape of the manufactured light emitting diode. It is the figure which showed the shape of the reflective structure formed in a circuit board. It is the figure which showed the shape of the reflective structure formed in a circuit board. It is the figure which showed the shape of the reflective structure and directivity structure which are formed in a circuit board. It is the schematic diagram which showed formation of the extraction part. FIG. 10 illustrates one embodiment of the present invention. FIG. 10 illustrates one embodiment of the present invention. FIG. 10 illustrates one embodiment of the present invention.

Explanation of symbols

10 First layer substrate 11 Chip 20 Second layer substrate 21 Through hole 30 Substrate 31 Chip 32 Primary molded product (whole)
33 Primary molded product (island shape)
34 reflector 100 circuit board 101 metal plate (metal layer)
102 Highly reflective coating 111 Metal plate (metal layer)
112 Metal plate (metal layer)
113 High reflective coating 114 High reflective coating 120 Extraction unit 130 Guide unit 140 Lens unit 151 Electrode 152 Electrode 160 Chip 161 Wire 162 Wire

Claims (21)

  A light extraction comprising a recess formed in a metal layer on a circuit board, a light-emitting diode chip installed in the recess, and a light-transmitting resin material formed so as to fill at least the recess and cover the light-emitting diode chip A light emitting device including a portion.   The light emitting device according to claim 1, wherein the concave portion is formed by half etching.   The light emitting device according to claim 1, wherein the horizontal sectional area of the concave portion is smaller as it is closer to the circuit board.   The light emitting element according to any one of claims 1 to 3, wherein the concave portion is coated with a highly reflective substance.   The light emitting device according to claim 4, wherein the highly reflective substance is a metal selected from the group consisting of Ag, Al, and Au.   The light-emitting element according to claim 1, wherein the light extraction unit is formed of a resin material or a silicone material having a refractive index lower than that of the light-emitting diode chip.   The light emitting element in any one of Claims 1-6 in which the part in which a recessed part is located among the light extraction parts is formed thickly compared with the other part.   The light emitting device according to any one of claims 1 to 7, further comprising a light guide portion formed above the circuit board so as to surround the concave portion and made of a substance having a high reflectance at least on the inside.   The light emitting device according to claim 8, wherein the light guide portion is made of a resin material.   The light emitting element according to claim 8 or 9, wherein the light guide portion is formed to have a predetermined inclination.   The light emitting element according to claim 8, wherein the light guide portion is formed on the light extraction portion.   The light emitting element according to claim 8, wherein the light guide portion is formed at a predetermined distance from the circuit board.   The light emitting element according to claim 1, further comprising a lens portion made of a light transmissive material on the light extraction portion.   The light-emitting device according to claim 13, wherein the light-transmitting material includes one or more additives selected from phosphors and diffusing agents.   The light emitting element according to claim 13 or 14, wherein the lens portion is made of a film.   The light emitting element in any one of Claims 1-15 which further contains the penetration path which connects the metal layer of a circuit board, and the electrode and / or metal plate of a circuit board lower part.   A first step of forming a recess in a metal layer on a circuit board; a second step of mounting a light-emitting diode chip in the recess; and a light-transmitting resin material so as to fill at least the recess and cover the light-emitting diode chip A third step of forming a light extraction part, a fourth step of forming a light guide part by molding a light-reflective resin material so as to surround the concave part above the circuit board, and surrounding the light guide part A method for manufacturing a light-emitting element, including a fifth step of forming a lens portion by molding a light-transmitting material in the space formed.   A first step of forming a recess in a metal layer on a circuit board; a second step of mounting a light-emitting diode chip in the recess; and a light-transmitting resin material so as to fill at least the recess and cover the light-emitting diode chip In the third step of forming the light extraction portion, the fourth step of forming the lens portion by molding a light transmissive material on the extraction portion, and the light so as to surround the recess at least on the side of the lens portion A method for manufacturing a light emitting element, comprising a fifth step of forming a light guide portion by molding a reflective resin material.   The step of mounting the light-emitting diode chip on the circuit board, and the light-reflective resin material is formed so that the horizontal cross-sectional area of the enclosed space is smaller as it is closer to the circuit board. And forming a light guide part, and forming a lens part by molding a light transmissive material in the enclosed space.   The method of claim 19, further comprising forming a reflective structure by providing a recess in a metal layer on the circuit board.   20. The method of claim 19, further comprising forming a reflective structure on the circuit board by bonding another circuit board having an opening corresponding to the location of the light emitting diode chip.

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