JP5097372B2 - High-current, high-efficiency surface-mount light-emitting diode lamp and method for manufacturing the same - Google Patents

Abstract

A surface-mounted light emitting diode lamp is provided to improve light use efficiency and obtain high directivity by enabling high current driving and by using an optical reflection structure. A plurality of sections are formed in a printed circuit board(117). An electrode layer is formed on the upper surface of the printed circuit board and includes first and second electrodes(111,112) that are electrically separated from each other. A light emitting diode chip(160) is mounted on the first electrode. The light emitting diode chip is covered with a molding member. The sections in the printed circuit board are formed by a dicing method and include a first section exposing the first electrode and a second section exposing the second electrode. The molding member includes a first molding member(120) covering the light emitting diode chip and a second molding member(140) formed on the first molding member wherein the second molding member includes a diffusing agent or a phosphor.

Description

  The present invention relates to a surface mount type (SMD) light emitting diode (LED) lamp and a method for manufacturing the same, and in particular, to improve performance at the time of driving a large current, that is, to improve efficiency while maintaining a small and thin shape characteristic. The present invention relates to a novel method capable of manufacturing an improved light emitting diode lamp and having manufacturing advantages such as an increase in production yield and a reduction in cost.

  A first example of the prior art relating to a surface-mounted light-emitting diode lamp that can be driven with a large current is shown in FIGS. In the first example, a lead is configured as shown in FIG. 1, and a lead frame 102 is obtained by injection molding a support base and a reflector. Further, a light emitting diode chip 110 is mounted on the lead frame 102 and an alumina ceramic body 108 is formed. Thereafter, each element is molded by a dispensing method, and the elements are separated by a trim technique. Then, the separated light emitting element is disposed on the printed circuit board 106 and the copper substrate pad 116 through the solder layer 104 to manufacture the light emitting diode lamp 100. The electrode lead 102 of the light-emitting diode lamp 100 also functions as a heat release passage, but has a small cross-sectional area and its effect is insignificant. Therefore, it is necessary to provide the through hole 112 and the heat dissipation pad 114 as a heat release structure. The release path of heat generated from the light emitting diode chip 110 is indicated by arrows. This structure can be driven even under a current of several tens to several hundred milliamperes (mA). However, as the drive current increases, the entire size increases and the production cost is high.

  2 and 3 show another example in which a light emitting diode chip is mounted on a lead frame. Descriptions of configurations common or corresponding to those in the example of FIG. 1 will be omitted as appropriate, and the same reference numerals will be given. In the light emitting diode lamp 120 of the example of FIG. 2 having a body 122 made of a polymer, heat is radiated using a metal (copper) slag body 124. Even in this conventional example, the heat release by the lead 102 hardly functions because the cross-sectional area is small. A light emitting diode lamp 140 having a ceramic (AIN) body 142 shown in FIG. 3 has a lead frame 144 made of a material having high thermal conductivity, and acts as a heat release path. However, as in the case of FIGS. 1 and 2, its function is not sufficient because the cross-sectional area is small. The light emitting diode lamp of the first example of the prior art described with reference to FIGS. 1 to 3 has a high rate of occurrence of defective products when it is produced in a small quantity, making it difficult to manage the yield and heat release. Additional costs such as increased material costs are incurred to provide the structure.

  A second example of the prior art is shown in FIGS. As shown in FIGS. 4 and 5, in the light emitting diode lamp of the second example, the light emitting diode chip 170 is mounted on the circuit board 164 supported by the leads 162, and then molded by transfer molding. The layer 166 is formed, and finally, each element is obtained by dicing. When molding, the phosphor 168 is added as an additive. In the example of the light emitting diode lamp 180 shown in FIG. 5, the lens portion 182 is formed by transfer molding. The feature of this conventional example is that light is provided with a substantially constant directivity by installing the reflector 184 and the guide 186 on the circuit board, and the production yield and cost can be reduced. However, since the heat dissipation structure is not provided, the light emission efficiency of the element is lowered, and driving under a large current is difficult.

  As in the first example described above, when the light emitting diode chip 110 is packaged using the lead frame 102, the normal dispensing method is used. However, the phosphor is changed depending on the center wavelength energy, spectrum and luminous flux of the chip 110. Since the concentration and mixing amount must be changed, it is difficult to control the yield of normal products. In addition, when adjusting the amount of dispensing in the dispensing method, it is necessary to adjust the amount of discharge with very high accuracy, and it is similarly difficult to manage the yield of normal products.

  There is a method of forming a lens portion (not shown) by providing a lens portion (not shown) using the transfer method or casting method using the lead frame 102, or by attaching and attaching a lens. The number of processes increases, and the production yield decreases due to the increase in the cost of the lead frame and the mold.

  When the light emitting diode chip 170 is mounted on the plane of the circuit board 164 as in the second example shown in FIG. 5 described above, the light generated from the chip 170 is reflected by the light reflecting plate 184 and has directivity. However, since the structure is thin, there is a problem that the performance is generally lowered compared to the case of using a lead frame substrate in terms of light reflection efficiency, light directivity, and other light utilization efficiency. Arise.

  An object of the present invention is to prevent excessive heat generation, which becomes a problem when a circuit board is used as a substrate for mounting a light emitting diode chip, to enable a large current drive, and to achieve high energy efficiency. .

The present invention has the following features in order to solve the problems of the prior art and achieve the above object.
That is, the present invention relates to a circuit board, a light-emitting diode chip integrated and mounted on a thermally conductive metal electrode layer on the circuit board, and a light extraction unit molded on the light-emitting diode chip. An exposed structure for heat emission in which at least a part of the bottom surface of the electrode layer on which the light-emitting diode chip is mounted is exposed, or a heat emission column having a through-hole substantially penetrating the electrode layer in the vertical direction The present invention relates to a light-emitting diode lamp including a heat dissipation portion including at least one of structures.

The present invention also provides a first step of preparing a circuit board on which light emitting diode chips can be integrated and mounted, a light emitting diode chip integrated and mounted on a thermally conductive metal electrode layer on the circuit board, and molded. A second step of forming a light extraction portion, a third step of forming an exposed structure for heat emission by exposing at least part of the metal layer of the electrode on which the light emitting diode chip is mounted as a heat emission portion, The present invention relates to a method for manufacturing a light emitting diode lamp, including a fourth step of separating each light emitting diode element.
Furthermore, the present invention relates to the above manufacturing method, wherein the third step includes exposing the entire bottom surface of the metal layer of the electrode by lapping or etching after molding in the second step.
Further, the present invention includes a third step in which, after molding in the second step, forming a concave portion extending linearly by dicing to expose a part of the bottom surface of the metal layer of the electrode, It is related with the said manufacturing method.

Furthermore, the present invention provides a first step of preparing a circuit board on which light-emitting diode chips can be integrated and mounted. As a heat-dissipating part, the heat conductive metal electrode layer on the circuit board is substantially vertically penetrated. A second step of forming a heat-dissipating pillar structure by forming through-holes to be formed, a third step of integrating and mounting a light-emitting diode chip on the metal electrode layer, and molding to form a light extraction part, each light emission The present invention relates to a method for manufacturing a light-emitting diode lamp, including a fourth step of separating a diode element.
Moreover, this invention relates to the said manufacturing method including removing the insulator layer of a circuit board so that an electrode layer may be supported by the light extraction part by which the mold was formed.
Further, in the present invention, after the through hole is provided in the second step, the inner surface of the through hole is plated with a heat conductive material, or the through hole is filled with the heat conductive material. It is related with the said manufacturing method including the process of forming the column structure for discharge | release.
Furthermore, in the first step, the present invention forms a first metal layer of an electrode having a thickness of 20 μm to 800 μm and containing Cu or Al, and (FR-4) epoxy under the metal layer. It is related with the said manufacturing method including forming the 200-800-micrometer-thick insulator layer which consists of resin, and forming the 2nd metal layer of a 20-3000-micrometer thickness under this insulator layer.

In the present invention, when the first metal layer is formed, the P-type region and the N-type region are separated by etching, and after etching, the surface of the first metal layer is plated with Ag. It is related with the said manufacturing method including providing a reflective structure by.
Furthermore, this invention relates to the said manufacturing method formed so that a reflective structure may have 2 or more types of curvature radii.
Furthermore, this invention relates to the said manufacturing method including forming a mold with the material of a refractive index in the range of 1.4-2.5, when forming a light extraction part.
Furthermore, according to the present invention, the light extraction portion is formed from a silicone or epoxy material to a thickness of 200 μm to 1000 μm, and can support the circuit board and the metal layer of the electrode separated into the P-type region and the N-type region by etching. It is related with the said manufacturing method including doing.

  Compared to a general method using a conventional lead frame and a dispensing method, the present invention is small and thin but has excellent heat release characteristics, can be driven with a large current, and greatly improves energy efficiency. . In particular, even in the case of mass production, cost is reduced because of excellent performance uniformity, yield and mass productivity. As a result, it is expected to contribute to the creation of demand for LEDs and greatly contribute to the development of the industry. In addition, it is possible to mount a large number of chips and a large number of chips, and it is easy to manage tablets such as phosphors and diffusing agents used in molding, which reduces the stock burden on producers. In addition, digital light output can be increased.

  As one aspect of the present invention, a first step of preparing a circuit board on which light emitting diode chips can be integrated and mounted, the light emitting diode chips are integrated and mounted on a thermally conductive metal electrode layer on the circuit board, A second step of forming a light extraction part by molding, a third step of forming an exposed structure for heat emission by exposing at least a part of the metal layer of the electrode on which the light emitting diode chip is mounted as a heat emission part; A method for manufacturing a light-emitting diode lamp including the fourth step of separating each light-emitting diode element will be described below as an example.

  In the first step, a circuit board comprising an electrode layer containing Cu, Al, etc., a Cu layer positioned below the electrode layer, and an FR-4 insulating layer sandwiched between the electrode layer and the Cu layer is prepared. To do. At this time, the electrode layer is preferably formed to a thickness of 20 μm to 800 μm, the insulating layer is formed to a thickness of 200 μm to 800 μm, and the Cu layer is preferably formed to a thickness of 20 μm to 3000 μm. Furthermore, in order to increase the reflection efficiency on the substrate, the electrode layer surface can be plated with a material having high reflectivity such as Ag, Al, or Au. Moreover, in order to improve the directivity of the light reflected by the substrate, it is possible to provide a recess in the electrode layer by half etching.

In the second step, an LED chip is mounted on the electrode layer of the circuit board prepared in the first step, and wire bonding is performed to connect the electrodes. Thereafter, molding is performed using a resin-based material having high transparency and a low refractive index, for example, silicone or epoxy material, and a light extraction portion (primary resin layer) is formed so as to cover the entire LED chip.
Furthermore, in order to improve the light efficiency of the lens, a layer having a different refractive index is formed, or for the purpose of reflecting or guiding light, various additives such as a phosphor are mixed with a light-transmitting resin, and the lens portion (Secondary resin layer) may be formed. It is also possible to adhere a film instead of a mold.

  In the third step, the Cu layer and the insulating layer on the lower surface are removed from the back surface of the circuit board by a dicing method, and the electrode layer is exposed to form a heat release portion. Here, the exposed structure for heat release may be formed as a groove-like heat release passage formed of a linearly extending recess formed in the circuit board, and the bottom surface of the electrode layer may be formed by a method such as lapping or etching. You may make it expose the whole. Furthermore, in the present invention, the thickness of the metal layer serving as an electrode can be increased, and the metal layer itself can contribute to heat dissipation. In particular, when the entire bottom surface of the electrode layer described above is exposed, almost all or most of the insulating layer under the electrode layer is removed, so that the LED chip is used instead of the removed insulating layer. It is necessary to give sufficient support to. Therefore, in the present invention, the light extraction unit may be formed to support the LED chip.

  In the fourth step, the light emitting element on which the LED chip created by the above procedure is mounted is separated for each unit by dicing.

  In the embodiment described above, the electrode exposure structure is provided as the heat release portion, but instead, the heat release portion may be formed by forming a through hole that substantially penetrates the electrode layer. In this case, it is preferable to first prepare a circuit board and form a through hole from the back side of the board before molding the light extraction portion. Further, the inner surface of the formed through hole is plated with a highly conductive metal such as Ag to form a passage through which heat is released. Alternatively, the heat release passage may be formed by filling the space of the through hole with a metal material having thermal conductivity.

In the second example of the prior art as well, the LED chip is mounted on the plane of the circuit board, but the emitted light from the chip is reflected by the light reflecting plate and needs to have directivity. However, since the structure is thin, the performance is generally reduced as compared with the case of using the lead frame substrate in terms of light reflection efficiency, light directivity and other light utilization efficiency. On the other hand, when the lead frame substrate is used, the light reflecting plate or the light guide portion is deteriorated by the light emitted from the chip.
In order to solve these problems, in the present invention, in order to improve reflection efficiency, directional characteristics, and other light use efficiency, that is, in order to increase the light extraction efficiency by inducing reflection of light incident on the side surface and the bottom surface. A reflector and a reflecting structure can be provided so that the extracted light is incident on the chip again and is not reabsorbed.

  More specifically, the light reflection plate structure and the directivity structure are formed by using an exposure process technique. In this case, it is preferable that the shape of the reflecting plate is formed so as to have a plurality of radii of curvature, and the downward light and the light toward the side surface have directivity characteristics. The reflective structure may be coated with a metal material such as Ag having a higher reflectance. At this time, the size of the reflection structure is optimized so that re-absorption of light emitted from the chip does not occur.

  A light-emitting diode lamp 10 which is an example of the present invention is shown with reference to FIG. A circuit board comprising a copper plate (electrode layer) 12, a copper pad 16 and an insulator layer 14 disposed therebetween is cut from the back by a dicing method to form a recess 30, and a part of the electrode layer 12 is formed. Expose. This is soldered (18) on the printed circuit board 24 through the copper pad 22, and the light emitting diode 10 is obtained. . A primary resin layer (light extraction portion) 26 and a secondary resin layer (lens portion) 28 are formed above the LED chip 20. Arrows in the figure indicate a path for releasing heat generated from the chip 20. In the illustrated example, four recesses 30 are provided, but the number and size thereof can be changed as appropriate according to design specifications such as drive current.

  In the description of each aspect of the present invention to be described later, the same or corresponding configuration as that shown in FIG. 6 will not be described as appropriate, and the same reference numerals as those in FIG.

  In the light emitting diode lamp 40 according to another aspect of the present invention shown in FIG. 7, the heat emission part is formed by exposing the entire bottom surface of the electrode layer 12. At this time, as shown in the figure, substantially the entire insulator layer below the electrode layer 12 is removed. In this aspect, the lower electrode layer 12 of the LED chip 20 is formed thicker than the conventional one, and has a high heat dissipation function in addition to the function as an original electrode.

  Further, FIG. 8 shows a light-emitting diode lamp 50 according to another aspect of the present invention in which a through hole 52 is formed in a circuit board as a heat release portion. As indicated by arrows in the figure, the heat generated from the LED chip 20 is released to the outside through the through hole 52. In order to enhance the heat dissipation function, the inner surface of the through hole 52 may be plated with a conductive material such as Ag or Au, or the through hole may be filled with a highly conductive material.

In order to give directional characteristics to the light emitted from the LED chip 20 according to some modified examples of the present invention , a light guide 62 can be installed around the chip 20. It can be fixed by taping around the inner and side surfaces of the lens portion 28, or can be molded using a resin material having a high reflectance. In this case, the reflecting surface can be formed to have a constant inclined surface. The said aspect is shown in FIG. 9, FIG.

  In order to improve the directivity and output characteristics of light from the LED chip 20, the reflective structure 82 may be formed by partially denting the electrode layer 12 of the circuit board by half etching. An example including the reflecting structure 82 is shown in FIGS. The reflective structure 82 can be formed to have one or a plurality of radii of curvature, or can be tapered, dished, or bowl-shaped to induce light directed toward the side surface and the bottom surface. Increasing sex and output. When the reflective structure 82 is formed by half-etching the copper electrode layer 12 to a certain thickness (for example, about 100 μm or more), the heat-dissipating portion 84 is formed not at the etched portion but at the end of the circuit board (see FIG. 12) is preferred. Further, if necessary, positioning can be performed as appropriate so that it can be performed simultaneously with the work of separating the elements.

It is a figure which shows the prior art of the alumina-ceramics package which comprises the penetration structure for heat dissipation. It is a figure which shows the prior art of the package which comprises the heat path of a metal slag structure. It is a figure which shows the prior art of the AIN package comprised with the heat | fever discharge | release frame. It is a figure which shows the prior art of the small and thin package using a circuit board.

It is a figure which shows the prior art of the package which attached the guide part and the transfer mold lens to the circuit board. It is a figure which shows an example of this invention which comprises the channel | path for heat release formed using the dicing method. It is a figure which shows an example of this invention which comprises the heat-dissipating part formed by exposing the whole electrode bottom face using the lapping method. It is a figure which shows an example of this invention which comprises the heat-dissipation part formed substantially penetrating the electrode layer.

It is a figure which shows another example of this invention which comprises the light guide structure. It is a figure which shows another example of this invention which comprises the light guide structure. It is a figure which shows another example of this invention which comprises the reflection structure of light. It is a figure which shows another example of this invention which comprises the reflection structure of light.

Explanation of symbols

10, 40, 50, 60, 70, 80, 90 Light emitting diode chip 12 Electrode layer 14 Insulator layer 16 Copper pad 18 Solder layer 20 LED chip 22 Copper pad 24 Printed circuit board 26 Primary resin layer (light extraction part)
28 Secondary resin layer (lens part)
30 Recess 52 Through-hole 62 Light guide 82 Reflective structure 84 Through-hole

Claims (12)

A method of manufacturing a light emitting diode lamp,
A first step of preparing a circuit board comprising a copper plate electrode layer, a Cu layer located below the electrode layer, and an insulator layer sandwiched between the electrode layer and the Cu layer ;
A second step in which LED chips are integrated and mounted on the electrode layer on the circuit board and molded to form a light extraction unit;
Third step to remove the Cu layer and the insulating layer of the lower surface from the rear surface of the circuit board to form a plurality of linear grooves like heat discharge path, causing expose at least a portion of the bottom surface of the electrode layer,
Fourth step of separating the light emitting element mounted with the LED chip for each unit
Including
The plurality of straight groove-shaped heat release passages include an end portion of the separated circuit board and at least one straight groove-like heat discharge passage in addition to the end portions.
A method for manufacturing the light emitting diode lamp. The method of manufacturing a light-emitting diode lamp according to claim 1, wherein in the third step, a plurality of linear groove-shaped heat release passages are formed by a dicing method. The method for manufacturing a light-emitting diode lamp according to claim 1, wherein in the fourth step, the light-emitting element is separated into units by dicing. The manufacturing method of the light emitting diode lamp as described in any one of Claims 1-3 including isolate | separating a copper plate electrode layer into a P-type area | region and an N-type area | region in a 1st process. The manufacturing method of the light emitting diode lamp as described in any one of Claims 1-4 including forming a recessed part reflective structure in an electrode layer in a 1st process. The method for manufacturing a light-emitting diode lamp according to any one of claims 1 to 5, wherein in the first step, the electrode layer surface is plated with a highly reflective material containing Ag, Al, or Au. The method for manufacturing a light-emitting diode lamp according to any one of claims 1 to 6, comprising exposing the entire bottom surface of the electrode layer in the third step. The light emitting diode lamp produced by the manufacturing method as described in any one of Claims 1-6. A light emitting diode lamp,
A circuit board composed of a copper plate electrode layer, a copper pad, and an insulator layer disposed therebetween ,
Said electrode layer, a light emitting diode chip mounted in an integrated,
A light extraction part molded on the light emitting diode chip;
A plurality of linear groove-shaped heat release passages formed by removing the copper pad and the insulating layer and exposing at least a part of the bottom surface of the electrode layer ;
Comprising
The plurality of linear groove-shaped heat release passages include an end portion of the circuit board and at least one straight groove-like heat discharge passage in addition to the end portion.
The light emitting diode lamp. The light emitting diode lamp according to claim 9, wherein the electrode layer is separated into a P-type region and an N-type region. The light-emitting diode lamp according to claim 9 or 10, wherein the electrode layer has a partially concave reflecting structure. The light emitting diode lamp of claim 11, wherein the reflective structure has one or more radii of curvature.

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