JP2009253169A - Light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable light-emitting device in which a sealing member is sealed in a cavity provided on a mounting surface, and the sealing member is prevented from flowing to a power feeding portion and there is no mounting defect. The purpose is to provide.
A support body 101, a light emitting element 106 placed on the upper surface side of the support body, a cavity formed on the lower surface side of the support body, and a protection element 102 placed on the cavity are covered. A light emitting device including a sealing member 103 having a recess or a protrusion on an inner wall of the cavity, the sealing member covering at least a part of the recess or the protrusion, and the cavity And a terminal electrode 105 on the lower surface side of the light emitting device.
[Selection] Figure 2

Description

  The present invention relates to a light-emitting device using a light-emitting element, and more particularly to a surface-mounted light-emitting device in which a protective element is mounted.

  For light emitting devices used as various light sources, light emitting elements such as light emitting diodes and semiconductor lasers are used.

  In such a light-emitting device, a protective element such as a Zener diode may be mounted on the light-emitting device in order to protect the light-emitting element from destruction due to overvoltage. Such a protective element is disposed adjacent to the light emitting element and is electrically connected to the light emitting element.

  For example, a light-emitting device disclosed in Patent Document 1 below includes an insulating substrate provided with first and second electrodes having different polarities, a light-emitting element disposed on the upper surface side of the first electrode, A protective element (for example, a Zener diode) disposed on the second electrode, and a sealing resin that covers the light emitting element and the conductive wire connected to the light emitting element are provided. Further, one electrode of the light emitting element is connected to the first electrode and the other electrode is connected to the second electrode by wires. On the other hand, the upper surface side electrode of the protective element is connected to the first electrode by a conductive wire, and the lower surface side electrode is connected to the second electrode via a conductive adhesive. In such a light-emitting device, the light extraction efficiency of the light-emitting device as a whole may be reduced when light from the light-emitting element is absorbed by the protective element or is blocked by the protective element.

  Therefore, as in the light emitting device disclosed in Patent Document 2 below, it has been proposed to provide a recess for placing the protective element on the surface opposite to the surface on which the light emitting element is placed. The light-emitting device configured as described above has sufficient brightness by arranging the light-emitting element at substantially the center of the light-emitting device without the light from the light-emitting element being absorbed by the protective element or shielded by the protective element. While being held, it is possible to provide a small surface-mount light-emitting device with anti-static measures.

Japanese Patent Application Laid-Open No. 11-54804.

JP 2001-36140 A.

  However, in the light emitting device disclosed in Patent Document 2, when resin is filled in the cavity in which the protective element is mounted, the resin rises along the terminal electrode extended into the cavity, and serves as a power feeding portion of the light emitting device As the resin flows to the terminal electrode (that is, the portion of the terminal electrode connected to the mounting substrate, etc.), the terminal portion is covered with the resin, and the thickness of the terminal portion is not stabilized due to the increase in thickness. There was a risk of device mounting failure. In addition, there is a problem that conduction with the mounting substrate may not be achieved. When the cavity is not sealed, there is a problem in that solder or the like when mounting the light emitting device flows into the cavity and a defect occurs.

  The present invention has been made to solve the above problem, and in a light emitting device in which a protective element placed in a cavity provided on a mounting surface of the light emitting device is sealed, a sealing member flows to a power feeding unit. An object of the present invention is to provide a highly reliable light-emitting device that is free from mounting defects and the like.

  In order to achieve the above object, a light-emitting device according to the present invention includes a support, a light-emitting element placed on the upper surface of the support, a cavity formed on the lower surface of the support, A light emitting device including a sealing member that covers a protective element placed in a cavity, the side wall of the cavity having a concave portion or a convex portion, and the sealing member is at least one of the concave portion or the convex portion. And a terminal electrode disposed outside the cavity on the lower surface side.

  In this light-emitting device, the protective element is preferably flip-chip mounted.

  Furthermore, it is preferable that the upper surface of the support has conductor wiring extending from the light emitting element mounting portion, and the conductor wiring is provided at both end portions of the upper surface.

  According to the light emitting device of the present invention, in the light emitting device in which the protective element placed in the cavity provided on the surface on which the terminal is disposed is sealed, the sealing resin is prevented from flowing to the power feeding portion, and the mounting failure Thus, a highly reliable light-emitting device can be provided.

  The best mode for carrying out the present invention will be described below. However, the embodiments shown below exemplify the light emitting device and the manufacturing method thereof for embodying the technical idea of the present invention, and the present invention does not limit the light emitting device and the manufacturing method thereof to the following. .

  Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the scope of the present invention only to the description unless otherwise specified. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in the following description, the same name and reference sign indicate the same or the same members, and detailed description will be omitted as appropriate.

  Embodiments of a light emitting device according to the present invention will be described below in detail with reference to the drawings.

<First Embodiment>
1 to 3 show a light emitting device 100 according to the present embodiment. FIG. 1 is a bottom view of the light emitting device according to the present embodiment, and FIG. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is a perspective view of the light emitting device according to this embodiment as viewed from above.

  As shown in FIGS. 1 and 2, the light emitting device 100 of the present embodiment is formed on a support 101, a light emitting element 106 placed on the upper surface side of the support 101, and a lower surface side of the support 101. And a protective element 102 placed in the cavity 109. In the present embodiment, the terminal electrode 105 is disposed on the lower surface of the support, that is, on the side where the above-described cavity is formed and outside the cavity, and a convex portion 104a and a concave portion 104b are provided on the side wall of the cavity. Have. By forming in this way, it is possible to prevent the sealing member 103 filled in the cavity from scooping up and flowing to the vicinity of the terminal electrode 105. Hereinafter, each structure of this Embodiment is explained in full detail.

(Concave or convex)
In this embodiment, the concave portion or the convex portion is formed on the side wall of the cavity, and is provided to prevent the sealing member 103 from scooping up along the side wall due to surface tension. Any shape that can increase the surface area of the cavity side wall and lengthen the scooping path may be used. Examples of the concave portion or the convex portion include a shape in which holes, grooves, protrusions, and the like are provided on the cavity side wall. Both the concave portion and the convex portion may be formed. Further, it is only necessary that the sealing member is formed at least on the part of the cavity side wall that rises.

  An example of such a recess or protrusion is shown in FIG. In FIG. 2, the convex portion 104a is formed by being provided on the side wall of the cavity so as to protrude inward. In this way, by forming a portion in which the cross-sectional area of the cavity opening is smaller than the cavity bottom surface, the convex portion 104 functions as a holding portion for holding the sealing member, and the sealing member is peeled off from the cavity. Can be suppressed. In this embodiment, a recess 104b is further formed on the opening side, in other words, on the lower surface side of the support 101. By providing the concave portion or the convex portion in this way and increasing the opening closest to the outside, the die bonder collet is less likely to contact when the protective element 102 is placed in the cavity, and the amount of the sealing member is controlled. This is also preferable.

(Support 101)
In this embodiment, the support 101 has a light emitting element 106 mounted on the upper surface side and a cavity 109 and a terminal electrode 105 for mounting a protective element on the lower surface side.

  Examples of the material of the support 101 in this embodiment include resins such as BT resin, glass epoxy resin, ceramics, glass, and heat resistant polymer. By forming with ceramics, a support having high heat resistance can be obtained. As the ceramic, for example, alumina, aluminum nitride, mullite, silicon carbide and the like are preferable.

  For example, a support using ceramics is formed by firing after forming a predetermined shape. As the support 101 of this embodiment, one or more ceramic green sheets can be used. Ceramics can take various shapes in the green sheet stage before firing. The conductor wiring in the ceramic support body is formed of a paste-like material in which a high-melting point metal such as tungsten or molybdenum is contained in a resin binder. A paste-like material is formed into a desired shape through a through hole provided in a green sheet by a method such as screen printing, and becomes a conductor wiring by firing ceramics. After laminating such green sheets, a ceramic support can be obtained by sintering. Since the conductor wiring formed so as to connect the upper surface side and the lower surface side through the through hole in this way does not cut the terminal electrode 105 when the support is diced into individual pieces, the burr or the like It is possible to easily and accurately perform the processing without generating. In addition, it is not necessary to route the electrodes, and the light emitting device can be further downsized.

  The cavity 109 can be formed by providing a through hole in the green sheet. As shown in FIG. 2, the support in this embodiment is formed by laminating and firing four green sheets 101a to 101d. In FIG. 2, the interface of each ceramic green sheet is shown by a solid line, which indicates that the support in this embodiment is formed by laminating a plurality of ceramic green sheets, and obtained by firing. As for the support, the interface between the individual ceramic green sheets is not always clear. In this embodiment, four greens are 101a which is the bottom surface of the cavity 109, 101b which has a through hole on the bottom surface side of the cavity, 101c which has a through hole smaller than 101b, and 101d which has a through hole larger than 101c. By laminating and firing the sheets in order, the support 101 having the convex portions 104a and the concave portions 104b on the side walls of the cavity is obtained.

  A conductor wiring connected to the light emitting element 106 to be described later is provided on the upper surface side of the support, and can be formed, for example, by vapor deposition or sputtering, photolithography, printing, etc., or electrolytic plating. .

  The support can also be insert-molded with a molding resin using a pair of positive and negative lead electrodes as a conductive member. Examples of such materials include thermoplastic resins and thermosetting resins, such as polyphthalamide (PPA), polycarbonate resin, polyphenylene sulfide (PPS), liquid crystal polymer (LCP), ABS resin, and epoxy resin. A resin such as a phenol resin, an acrylic resin, or a PBT resin is preferable. When the support is formed by insert molding, the concave or convex portion can be formed by providing the corresponding mold with a shape corresponding to the concave or convex portion.

(Protective element 102)
The protection element 102 in this embodiment is placed in a cavity 109 formed on the lower surface side of the support 101 and sealed with a sealing member 103.

  In this embodiment, the protective element 102 is electrically connected so as to protect the light emitting element 106 against at least a reverse voltage that can be applied to the light emitting element 106 mounted on the upper surface side of the support. Since the light-emitting element 106 is mounted on the side opposite to the side on which the light-emitting element 106 is mounted, light from the light-emitting element 106 is not absorbed or shielded by the protective element 102. The light distribution characteristic can be made substantially symmetric with respect to the center while sufficiently maintaining luminance by being arranged at the center, and a small surface-mount light emitting device with anti-static measures can be obtained.

  The protection element 102 is electrically connected to a conductor wiring provided on the support 101 or a lead frame. For the electrical connection, when positive and negative electrodes are provided on the same surface side, flip chip bonding can be performed via wire bonding or bumps. Flip chip bonding is preferable because a thin light-emitting device can be obtained because it is not necessary to use a wire. Further, when the positive and negative electrodes of the protective element 102 are provided on the upper surface side and the back surface side, the back surface side electrode is usually die-bonded to a conductive portion such as a conductor wiring or a lead frame via a conductive adhesive. By doing so, it connects with one terminal electrode 105 of a support body.

(Sealing member 103)
The sealing member 103 in this embodiment is a member that protects the protection element 102 mounted in the cavity 109 formed in the support body 101 from dust, moisture, external force, and the like. In particular, in the light emitting device 100 of this embodiment, since the terminal electrode 105 of the light emitting device and the cavity for mounting the protection element 102 are formed on the same surface, solder or the like when mounting the light emitting element flows into the cavity. There is a problem that defects occur. Such a problem is solved by sealing the cavity with the sealing member 103.

  Examples of the material of the sealing member 103 include silicone resin, epoxy resin, and urea resin. A resin having a small linear expansion coefficient is preferable because stress on the protective element, a wire for connecting the protective element and the conductor wiring, a bump, and the like can be reduced. Examples of such a resin include an epoxy resin. In addition, since the thermal expansion of the resin can be reduced by adding an additive, for example, a silicone-based resin including an additive may be used. In the present invention, since the sealing member 103 that seals the protective element 102 seals only the protective element 102, it is necessary to consider the optical characteristics as in the case where the light emitting element 106 is simultaneously sealed. In addition, the degree of freedom in selecting the material of the sealing member 103 can be increased.

  By disposing such a sealing member 103 inside the cavity 109, the sealing resin 103 does not crawl up and does not spread on the terminal electrode described later.

(Terminal electrode 105)
The terminal electrode 105 in this embodiment is for electrically connecting the light-emitting element 106 and the protection element 102 mounted on the support 101 and can be used as a mounting terminal. Specifically, a conductor part formed on the support, a lead frame embedded in the support and integrally formed with the support, and the like can be given.

  For example, when a ceramic support is used, it is electrically connected to the conductor wiring in the support. As described above, the green sheet is laminated and fired as described above, and after forming the support, a through hole is provided in the mounting portion, and the through hole is filled with a conductive member. And the lower surface side are electrically connected. In addition, a metal layer serving as a base for the terminal electrode 105 may be formed at the time of firing described above, and the terminal electrode 105 may be plated by plating.

  In this embodiment, the cavity 109 that accommodates the protection element 102 is formed on the surface having the terminal electrode 105, that is, on the lower surface side of the support body and outside the cavity, but the rising of the sealing member 103 is suppressed. Therefore, the terminal electrode 105 can be made large. By increasing the terminal electrode 105, heat dissipation can be improved. Note that it is preferable that the cavity is disposed at a certain distance (α in FIG. 1) from the terminal electrode in consideration of inflow of solder or the like during mounting.

(Light emitting element 106)
In this embodiment, an LED chip will be described as an example of the light-emitting element 106. Examples of the semiconductor light-emitting element that constitutes the LED chip include those using various semiconductors such as ZnSe and GaN. However, in the case of a light-emitting device having a fluorescent material, the short-circuit that can efficiently excite the fluorescent material. wavelength capable of emitting nitride semiconductor _{(in X Al Y Ga 1-} X-Y N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) is preferably exemplified. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal. For example, the LED chip can be a light emitting element that outputs not only visible light but also ultraviolet rays and infrared rays. In addition, the light emitting element 106 can be electrically and mechanically connected to a conductor wiring of an auxiliary member called a support or a submount through a conductive material called a bump.

  In this embodiment, the light emitting element 106 is flip-chip bonded to a conductor wiring provided on the upper surface of the support 101 via a bump, and is covered with a covering member 107 made of a resin containing a fluorescent substance.

<Second Embodiment>
As shown in FIGS. 4 and 5, the light emitting device 200 according to the second embodiment includes a support body 201 and a terminal electrode 205 by insert molding a pair of positive and negative lead electrodes with a molding resin. is doing. 4 is a cross-sectional view taken along the line BB in FIG. A cavity is provided on each of the upper surface side and the lower surface side of the support 201, and the light emitting element 106 is placed in the cavity on the upper surface side, and the protection element 102 is placed in the cavity 109 on the lower surface side. A recess 204 is formed in the side wall of the cavity 109 formed on the lower surface of the support 201, and the sealing member 103 is disposed inside the cavity. Also in this embodiment, since the recess 204 is formed, the sealing member 103 does not crawl up and flow to the terminal electrode 205. A translucent coating material 207 is filled in the cavity on the upper surface side.

  Next, specific examples of the present invention will be described, but the present invention is not limited thereto.

As shown in FIGS. 1 to 3, the light emitting device 100 according to the present embodiment has a cavity formed on the lower surface of a ceramic support 101, a semiconductor element 102 as a protective element is mounted in the cavity, and a sealing member 103. Is filled. Protrusions 104 are formed on the cavity side walls. A semiconductor light emitting device capable of emitting white light by mounting four light emitting elements 106 arranged in the longitudinal direction on the upper surface of such a support and covering with a translucent coating material 106 made of a resin containing a phosphor. It is a device.

A method for manufacturing the light emitting device 100 will be described with reference to FIGS.
First, a Zener diode is prepared as the protection element 102. Positive and negative electrodes are respectively formed on the surface of the protective element. In addition to the protective elements, four square light emitting elements are prepared. This light emitting element is made of a nitride semiconductor that emits blue light, and emits light having a wavelength of about 455 nm. Positive and negative electrodes are respectively formed on the surface of the light emitting element.

  Next, as shown in FIG. 6, a support is formed. The support in this embodiment is formed by laminating and firing green sheets 101a to 101d mainly composed of aluminum nitride as a ceramic material. By forming through holes of different sizes in the ceramic green sheets 101b, 101c, and 101d, laminating them and firing, a cavity 109 is formed on the lower surface side (upward in FIG. 6) of the support, and its side walls A convex portion 104a and a concave portion 104b are formed. The external dimensions of the support 101 are 2.5 mm × 4.5 mm × 1.0 mm, which is a substantially rectangular parallelepiped. The cavity 109 is formed in the substantially center part of the support body 101, and the bottom face (mounting surface of the protection element) of the cavity is 1.6 mm × 0.7 mm. The step (β in FIG. 1) between the cavity side wall and the convex portion 104 is 0.05 mm. As shown in FIG. 1, the cavity opening is rounded at the corner, thereby suppressing the sealing resin from creeping up along the corner. Positive and negative terminal electrodes 105 are formed so as to face each other with the cavity interposed therebetween. Further, the gap (α in FIG. 1) between the cavity and the terminal electrode 105 is 0.15 mm.

  After polishing the upper surface side (lower side in FIG. 6) of the support thus formed, a conductor wiring 108 for mounting the light emitting element 106 is formed by vapor deposition. The conductor wiring 108 is electrically connected to the terminal electrode 105 on the lower surface side of the support 101 through a through hole (not shown). Since it is difficult to flatten the surface of the conductor wiring connected to the through hole, in this embodiment, the conductor wiring 108 is extended to a portion where the light emitting element is not mounted, and the extension portion and the through hole are formed. Are connected inside the support. Thereby, flatness can be ensured in the mounting portion of the light emitting element.

  In addition, by forming the extending portions on both ends of the upper surface of the support body 101 instead of one side, when the support body is sucked and fixed in order to place the protective element 102 in the cavity 109 on the lower surface side, By attracting and fixing the extending portion, the inclination of the support can be suppressed, and the mounting accuracy of the protection element can be improved.

  As shown in FIG. 7, the protective element 102 is flip-chip bonded to the conductor wiring formed in the cavity 109 of the support 101 thus formed. After that, as shown in FIG. 8, the support 101 is inverted and four light emitting elements 106 are flip-chip mounted on the upper surface of the support 101. A bump made of gold is used for bonding.

  Subsequently, as shown in FIG. 9, a translucent covering material 107 made of a silicone resin containing a YAG phosphor is formed on the main light extraction surface and the side surface of the light emitting element 106 by printing. Thereby, a light emitting device capable of emitting white light can be obtained. Further, as shown in FIGS. 10 and 11, the substrate is inverted again, the cavity in which the protection element 102 is mounted is sealed with a sealing member 103 made of epoxy resin, and cured so as to cover the convex portion 104 a.

  In the light emitting device 100 formed as described above, since the convex portion 104 a and the concave portion 104 b are formed, the sealing member 103 does not crawl up and flow to the terminal electrode 105. Thereby, even if a protective element is arranged on the lower surface side of the support, the terminal electrode 105 can be formed widely, and a light emitting device with high heat dissipation can be obtained.

  It can be used for various light sources such as illumination light sources, various indicator light sources, in-vehicle light sources, display light sources, liquid crystal backlight light sources, traffic lights, in-vehicle components, and signboard channel letters.

It is a bottom view in the light-emitting device of this invention. It is sectional drawing in the light-emitting device of this invention. It is a perspective view in the light-emitting device of this invention. It is sectional drawing in the light-emitting device of this invention. It is a bottom view in the light-emitting device of this invention. It is sectional drawing which shows the manufacturing process of the light-emitting device of this invention. It is sectional drawing which shows the manufacturing process of the light-emitting device of this invention. It is sectional drawing which shows the manufacturing process of the light-emitting device of this invention. It is sectional drawing which shows the manufacturing process of the light-emitting device of this invention. It is sectional drawing which shows the manufacturing process of the light-emitting device of this invention. It is sectional drawing which shows the manufacturing process of the light-emitting device of this invention.

Explanation of symbols

100, 200 Light emitting device 101, 201 Support 101a, 101b, 101c, 101d Ceramic green sheet 102 Protective element 103 Sealing member 104a Convex 104b, 204 Concave 105, 205 Terminal electrode 106 Light emitting element 107, 207 Translucent covering member 108 Conductor wiring 109 Cavity

Claims (3)

A support body, a light emitting element placed on the upper surface side of the support body, a cavity formed on the lower surface side of the support body, and a sealing member that covers the protection element placed in the cavity. A light emitting device,
Having a concave or convex portion on the side wall of the cavity;
The sealing member covers at least a part of the concave portion or the convex portion, and is disposed inside the cavity;
A light emitting device comprising a terminal electrode outside the cavity on the lower surface side. The light emitting device according to claim 1, wherein the protective element is flip-chip mounted. 3. The light emitting device according to claim 1, further comprising: a conductor wiring extending from a light emitting element mounting portion on an upper surface of the support, wherein the conductor wiring is provided at both end portions of the upper surface.

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