JP4176067B2 - Chip type LED - Google Patents

Description

  The present invention relates to a chip type LED in which an LED element (bare chip) is housed in a ceramic package, and more particularly to a chip type LED flip-chip mounted on a substrate.

  LEDs are used in flat displays such as signboards and advertising towers. There are two types of LEDs used in LED displays that are currently mass-produced: a bullet-type lead type LED and a direct bonding type in which an LED element (bare chip) is directly mounted on a substrate. Since a bullet-type lead type LED can achieve a considerably high brightness, it is mainly adopted for outdoor use. However, since the LED itself is large, it is difficult to make a small-sized display. On the other hand, the direct bonding type is easy to make a small size display because the LED itself is small. However, since the LED elements are directly mounted on the substrate, it is difficult to manage the brightness of the LEDs one by one, and it is difficult to maintain the uniformity of brightness as a display.

  On the other hand, there has conventionally been a chip type LED as shown in FIG. This is because the LED element 23 is placed on the insulating ceramic support member 21 on which the conductor layer is formed, the electrode 24 and the electrode terminal 22 of the LED element 23 are wire-bonded, and the sealing resin 26 is placed in the cavity. It is a structure that fills and solidifies. A high-density display LED display can be realized by surface mounting the chip type LED on one plane. And since the brightness | luminance of LED can be confirmed before mounting, there is no problem which impairs the uniformity of the brightness as a display.

  However, this chip type LED has a problem of luminance reduction due to the wire blocking light emitted from the LED element 23. In particular, when a gold wire is used for the wire, there is a problem of a decrease in luminance and a change in luminescent color tone due to absorption in the blue region.

  Moreover, in order to protect a wire, it is necessary to form a cavity with the LED element 23 and the partition which covers a wire.

  Furthermore, in order to fix the LED element 23 in the cavity, the cavity is filled with the sealing resin 26, which is caused by the heat generated when the LED element 23 is energized. Chip type LED due to expansion, causing peeling of the wire and the LED element 23, and causing degradation of the sealing resin 26 due to a part of the ultraviolet light emitted from the LED element, thereby reducing the permeability of the resin There is a problem that causes a decrease in brightness.

  Furthermore, on the manufacturing method of the chip type LED, an LED element is placed on the substrate, and after wire bonding and sealing resin are injected, the chip type LED is obtained by indexing each ceramic support member (package). Yes. At the time of the indexing, the ceramic support member 21 is distorted, and the LED element 23 falls off.

  Accordingly, the present invention has been made in view of such circumstances, and a first object is to provide a chip type LED that realizes an LED display capable of displaying a higher density.

  The second object is to improve luminance by adopting a structure in which light emitted from the LED element is not blocked by a wire.

  A third object is to provide a structure that does not require a cavity for wire protection.

  The fourth object is to provide a structure in which the LED element does not fall off due to distortion that occurs when indexing to the ceramic support member unit.

  As a result of intensive studies on the above-described problems, the present inventors have found that the problem can be solved by flip-chip mounting an LED element having a pair of electrodes on the same surface side to a ceramic LED package, and the present invention has been completed. It was.

That is, the present invention includes (a) an LED element having a pair of electrodes on the same surface side, and a ceramic support member fixing the LED element, and (b) the ceramic support member being fixed close to each other. The electrode terminal is printed with a conductor paste and printed with a conductor paste, and then pressed with a blade in the thickness direction of the ceramic green sheet to form a half-cut split groove in the ceramic green sheet the are formed through, the electrode (c) LED element, is flip-chip connected via conductive brazing material to the electrode terminals of the support member of ceramics, with respect to a plane that is placed is (d) LED element The outer edge of the ceramic support member in the vertical direction is to index the ceramic substrate on which the LED element is mounted along the half-cut line. (E) The ceramic support member relates to a chip-type LED having a portion that is half-cut in the thickness direction of the ceramic and a portion that remains unbroken and remains broken.

  In particular, since the auxiliary hole is formed so that the center is located on the half-cut line on the ceramic substrate, the division is further facilitated, and the auxiliary hole is formed so that the center is located at the intersection of the half-cut lines. Most preferably.

Moreover, the manufacturing method of chip type LED is provided with each process shown below, It is characterized by the above-mentioned.
(P) Conducting a conductor printing for producing an electrode formed by indexing the ceramic green sheet as a chip type LED, (q) For indexing as a chip type LED on the ceramic green sheet subjected to the conductor printing A step of producing a half-cut line, (r) a step of degreasing and then sintering the green sheet on which the conductor printing and the half-cut line were produced, and (s) flip chip connecting the LED element to the sintered ceramic substrate. Step (t) A step of indexing a ceramic substrate to which the LED element is flip-chip connected along a half-cut line.

  By forming the auxiliary hole so that the center is located on the half cut line of the green sheet, it becomes easier to divide the sintered ceramic substrate, and the center is located at the intersection of the half cut line of the green sheet. Most preferably, auxiliary holes are formed.

  Since the present invention is configured as described above, the following effects can be obtained.

  By adopting the configuration according to the present invention, the flip chip connection without using a wire for supplying power to the LED element is achieved, and the wire does not block the light emission from the LED element, thereby eliminating the problem of lowering the luminance.

  Also, a cavity that protects the wire is not required. As a result, the chip-type LED becomes compact and high-density mounting is possible, and thus, for example, an LED display capable of high-density display can be realized.

  Furthermore, in the conventional structure, in order to fix the LED element in the cavity, it has been forced to take a structure in which the sealing resin is filled in the cavity. As a result, the sealing resin expands due to the heat generated when the LED element is energized, causing the resin and the LED element to peel off, or causing part of the light emitted from the LED element to cause deterioration of the resin, Decreasing the resin permeability caused the LED brightness to decrease. On the other hand, in the structure of the present invention, since there is no cavity, there is no problem of peeling due to expansion, and light emission from the LED is not blocked by the sealing resin.

  The LED element is flip-chip connected to the electrode terminal of the ceramic support member, and the outer edge is half-cut, so in addition to the brittleness unique to ceramics, it can be divided with high precision and is less susceptible to distortion. In addition, the problem of peeling of the LED elements is minimized.

  Further, by adopting the above-described configuration, it is possible to obtain a chip type LED in which the LED element is less likely to be distorted at the time of indexing and the yield of peeling is reduced.

  Furthermore, with the above-described configuration, it is possible to obtain a chip-type LED that is less susceptible to distortion of the LED element at the time of indexing and has a low yield reduction due to peeling.

  The chip type LED of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic cross-sectional view of a chip-type LED of the present invention. FIG. 3 shows a plan view of the ceramic substrate before the indexing step. FIG. 4 shows a plan view of the chip type LED of the present invention. A pair of electrode terminals 12 are formed on a ceramic support member 11, and a pair of electrodes 14 on the surface of the LED element 13 are flip-chip connected by a conductive brazing material 15. In order to firmly bond the LED element 13 to the ceramic support member, a sealing resin 16 is injected into the gap between the LED element and the support.

  The ceramic support member only needs to have a structure in which the LED element can be placed and electrically connected, and alumina, aluminum nitride, and mullite can be preferably used as the ceramic material. By selecting ceramics as the support member, there is insulation, and conductor wiring can be directly formed thereon by a printing method or the like.

  The pair of electrode terminals that are fixed close to each other means that the electrode terminal 12 is short-circuited to the electrode 14 of the LED element 13 on the same surface side when the LED element 13 is placed and fixed with the conductive brazing agent 15. It is in a state of being close enough to be able to supply power without doing.

  The flip chip connection is a method in which a pair of electrodes 14 of the LED element 13 are connected to a pair of electrode terminals provided on the ceramic support member 11 so as to face each other. By this method, it is possible to solve various problems caused by the wire bonding connection.

  The outer edge of the ceramic support member in the direction perpendicular to the plane on which the LED element is placed is the one in which the LED element 33 is connected to the ceramic substrate 31 in advance in the manufacturing process for producing the ceramic support member. It is obtained by indexing along the half-cut line 38 of the dotted line. With this half-cut line 38, the ceramic substrate can be indexed very easily. By this indexing, a chip type LED is obtained. The outer edge 47 produced through this indexing process has a feature that a cracked mark remains because it is formed along the half-cut line.

  Indexing is further facilitated by forming the auxiliary hole so that the center is positioned on the half-cut line of the ceramic substrate.

  Since the auxiliary hole is formed so that the center is located at the intersection of the half cut lines, irregular cracks at the corners can be prevented, and the chip type LEDs can be more easily divided. As a result, since there is no distortion, the LED element does not drop out. In this example, a square auxiliary hole 39 is formed so that the center of the auxiliary hole is located at the intersection of the half cut lines.

  Moreover, the manufacturing method of chip type LED of this invention is demonstrated below. FIG. 5 is a schematic cross-sectional view illustrating a half cut of a green sheet.

  The ceramic green sheet is a sheet formed by, for example, using alumina or the like as a main component and adding an organic binder, a solvent, and a dispersant to the ceramic substrate. For example, conductor printing can be performed by printing a conductor paste mainly composed of tungsten.

  Half-cutting is to put a split groove in the green sheet by pressing with a blade in the thickness direction of the green sheet. In other words, it is not completely cut out, but is cut out leaving a part.

  The degreasing of the green sheet is to remove the binder and solvent of the green sheet by combustion decomposition, and in the subsequent sintering step, the ceramic powder is sintered to form a ceramic substrate. Conductor printing also forms conductor wiring. Here, the ceramic substrate refers to a substrate on which a plurality of LEDs having conductor wiring can be mounted, and the ceramic support member is obtained by dividing the ceramic substrate along a half-cut line. The electrode terminal on the ceramic support member 11 is formed by dividing the conductor wiring of the ceramic substrate along this half cut line.

  By forming the auxiliary hole so that the center is located on the half cut line of the green sheet, it becomes easier to divide the sintered ceramic substrate, and the center is located at the intersection of the half cut line of the green sheet. Most preferably, auxiliary holes are formed.

  FIG. 3 shows a plan view of the ceramic substrate before the indexing step. FIG. 4 shows a plan view of the chip type LED of the present invention. FIG. 6 is a plan view of a green sheet on which conductor printing is formed. FIG. 7 is a plan view of a green sheet with auxiliary holes.

  A solvent, a dispersant, a binder, and a plasticizer were added to the alumina powder to form a slurry, and the alumina slurry was discharged by a doctor blade method and dried to obtain a green sheet.

  According to a conventional method, through holes were opened for the purpose of connecting conductor printing on both sides of the green sheet, and a tungsten paste was printed on both sides by a screen printing method to obtain a green sheet subjected to conductor printing 62.

  Next, a half-cut line was formed using a cutting machine so that a square auxiliary hole was penetrated using a press machine, and the center was located in an auxiliary hole after that.

  The auxiliary hole and the half cut processed green sheet were dried, degreased and sintered according to a conventional method to obtain a ceramic substrate on which a tungsten conductor wiring was formed. Noble metal plating was applied to the tungsten conductor wiring.

  The LED element 13 has a pair of electrodes on the lower surface and emits light upward when the electrodes are energized. For the LED element, for example, a nitride-based LED in which a nitride semiconductor is grown on a sapphire substrate and the active layer can be expressed by the general formula InxAlyGa1-x-yN can be used. In this type of LED, the emission peak wavelength can be freely changed according to the value of x. For example, if x = 0.3 is set, blue light emission having a peak wavelength of 450 nm is obtained, if x = 0.53, green light emission having a peak wavelength of 520 nm is obtained, and if x = 0.95 is set, peak light emission is obtained. Red light emission with a wavelength of 630 nm can be obtained. However, the LED that can be used in the present invention is not limited to the nitride system, and any LED that can be flip chip mounted and has a pair of electrodes on the same surface side can be used.

  A pair of electrodes 14 of the LED element was electrically connected to the conductor wiring 12 wired on the ceramic substrate 11 via a conductive brazing material 15. As the conductive brazing agent, for example, a low melting point metal such as solder, or a metal paste in which a conductive agent and an adhesive are kneaded can be used. In order to firmly fix the LED element 13 on the ceramic substrate, the sealing resin 16 is injected into the gap between the LED element and the ceramic substrate.

  By indexing along the half-cut line 38, the electrode terminal 12 is formed on the ceramic support member 11, the LED element is flip-chip connected to the chip-type LED, and the outer edge 17 is half-cut processed. It was.

  The chip type LED of the present invention can be used for a display, a lighting device and the like.

The schematic cross section of chip type LED of this invention is shown. The schematic cross section of chip type LED for a comparison is shown. The top view of the ceramic substrate before an indexing process is shown. The top view of chip type LED of this invention is shown. It is a schematic cross section explaining the half cut of a green sheet. It is a top view of the green sheet which formed conductor printing. It is a top view of the green sheet which opened the auxiliary hole.

Explanation of symbols

11, 21 Ceramic support members 12, 22 Electrode terminals 13, 23, 33 LED elements 14, 24 Electrode 15 Brazing agent 16, 26 Sealing resin 17 Outer edge 31 Ceramic substrate 32 Conductor wiring 38 Half cut line 39 Auxiliary hole 61 Green sheet 62 Conductor printing

Claims (4)

(A) an LED element having a pair of electrodes on the same surface side, and a ceramic support member fixing the LED element; (b) a pair of electrode terminals fixed to each other close to the ceramic support member The electrode terminal is formed through a process of printing a conductive paste by printing a conductive paste and then pressing the blade in the thickness direction of the ceramic green sheet with a blade to put a half-cut split groove in the ceramic green sheet. , the electrodes of (c) LED element, is flip-chip connected via conductive brazing material to the electrode terminals of the support member of ceramics, in a direction perpendicular to the plane which is placed thereon (d) LED element The outer edge of the ceramic support member is formed by indexing the ceramic substrate on which the LED element is mounted along the half-cut line. (E) The ceramic support member is a chip-type LED having a portion that is half-cut in the thickness direction of the ceramic and a portion that remains unbroken and remains broken. (P) Conductive printing for producing an electrode formed by indexing the ceramic green sheet as a chip type LED, (q) Ceramics for indexing as a chip type LED on the ceramic green sheet subjected to the conductor printing A step of creating a half cut line by pressing with a blade in the thickness direction of the green sheet to create a half cut line in the ceramic green sheet, (r) degreasing the ceramic green sheet that produced the conductor printing and the half cut line, Next, a step of sintering, (s) a step of flip-chip connecting an LED element having a pair of electrodes on the same surface side to the sintered ceramic substrate, and (t) a ceramic substrate on which the LED element is flip-chip connected. A step of indexing along the half-cut line Method for manufacturing a chip type LED, wherein the door.   The method for manufacturing a chip-type LED according to claim 2, wherein the auxiliary hole is formed so that the center is located on the half cut line of the ceramic green sheet.   The method for manufacturing a chip-type LED according to claim 2, wherein the auxiliary hole is formed so that the center is located at the intersection of the half cut lines of the ceramic green sheet.

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