JP2007013027A - Porcelain enamel substrate for mounting light emitting element, light emitting element module, illumination device, display device, and traffic signal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a porcelain enamel substrate for mounting a light emitting element which can mount an light emitting element at high density, a light emitting element module in which the light emitting element is mounted on the porcelain enamel substrate, and a display device, an illumination device and a traffic signal, each employing this module. <P>SOLUTION: The porcelain enamel substrate 13 for mounting a light emitting element is characterized in that a through hole 16 is formed on the porcelain enamel substrate having a core metal 14 covered with a porcelain enamel layer 15, and a through hole electrode 17 obtained by filling a conductor in the through hole is formed. The light emitting element module 10 is characterized in that the light emitting element 11 is mounted on the porcelain enamel substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting element mounting hollow substrate for mounting a light emitting element such as a light emitting diode (hereinafter referred to as LED), a light emitting element module such as an LED module having the light emitting element mounted on the hollow substrate, and the light emitting element. The present invention relates to a lighting device, a display device, and a traffic signal device using a module.

  In the case where a light emitting element such as an LED is used in a lighting device, a display device, a traffic signal device, and the like, an improvement in light emission intensity of the light emitting element is an important issue. As a means for improving the intensity of light emitted from the light emitting element, it is conceivable to increase a current value applied to the light emitting element by mounting a plurality of light emitting elements at a high density and lighting them simultaneously (for example, see Patent Document 1). . When it is intended to manufacture a light emitting element module by mounting a plurality of light emitting elements at a high density on a substrate or a surface mount package, for example, an electrode arrangement as shown in FIG. 5 may be taken. 5A is a plan view of the light emitting element module, and FIG. 5B is a cross-sectional view. This light emitting element module is provided with a plurality of electrodes 3 bent from the left and right toward the mounting area on the substrate 4, the light emitting element 1 is mounted on one electrode 3 of the mounting area, and the other The electrode and the light emitting element 1 are electrically connected by a wire bond 2, and the mounting region is collectively sealed with a sealing resin 5.

Furthermore, since the amount of heat generated from the light emitting elements is increased by mounting a plurality of light emitting elements, an aluminum laminated substrate or a ceramic substrate is generally used. On the other hand, even when the amount of current input to the light emitting element is increased, the amount of heat generated per light emitting element increases, and thus a heat dissipation substrate similar to the above is required. Note that when the heat radiation is not performed well, the temperature (junction temperature) at the time of operation of the light emitting element is increased, so that the light emitting efficiency of the light emitting element is decreased and the long-term reliability of the light emitting element is further decreased.
JP 2001-326389 A

  As described above, in order to mount a plurality of light emitting elements, it is necessary to prepare positive and negative electrodes individually for each light emitting element. On the other hand, since there is an appropriate range of product sizes such as lighting devices, display devices and traffic signals to be applied, the size of the light emitting element module cannot be simply increased. On the premise that a light emitting element module is manufactured within a predetermined size, when it is attempted to mount a larger number of light emitting elements on a substrate, it is necessary to mount them at a high density.

  Further, since the amount of heat generated from the light emitting elements increases by increasing the number of light emitting elements to be mounted, it is necessary to use a heat dissipation substrate from the viewpoint of the reliability described above. It is difficult to produce a fine pitch electrode from the viewpoint that heat shrinkage due to heat is large among the material characteristics of a general heat dissipation substrate such as ceramics, and it is practically difficult to mount it at high density because of its electrode design.

  On the other hand, in an aluminum laminated substrate, the electrodes can be fine pitched by bonding copper foil, forming electrodes by printing, or the like. When it is going to produce the electrode structure as shown in FIG. 5 on a substrate, since the number of electrodes to be produced is large and complicated, the technical difficulty is high, and such a high-density electrode is produced. Want to avoid as much as possible. Therefore, a structure in which a common electrode is provided at the center of the light emitting element mounting portion on the substrate is conceivable. In order to simplify the common electrode, it is preferable to provide a through hole in the substrate so that one electrode is electrically connected to the back surface of the substrate. However, in the case of an aluminum laminated substrate, since the aluminum plate is disposed on the back surface of the laminated structure, there is a problem that insulation of the substrate cannot be ensured. FIG. 6 is a view showing an example of an aluminum laminated substrate. In FIG. 6, reference numeral 6 denotes an aluminum plate, 7 denotes an insulating layer, and 8 denotes a substrate electrode. Needless to say, aluminum is a conductive material, but when an electric circuit is turned to the back side through a through hole, electricity flows through the aluminum plate. Although it is possible to use the entire aluminum plate as a common electrode, it is not a preferable form for safety because it is not insulated.

  The present invention has been made in view of the above circumstances, and a light-emitting element mounting enamel substrate on which light-emitting elements can be mounted at high density, a light-emitting element module in which the light-emitting element is mounted on the enamel substrate, an illumination device using the same, and a display device The purpose is to provide traffic signals.

  In order to achieve the above object, the present invention is characterized in that a through hole is provided in a hollow substrate in which a core metal is covered with a hollow layer, and a through hole electrode in which a conductor is filled in the through hole is provided. A hollow substrate for mounting a light emitting element is provided.

In the enamel substrate for mounting a light emitting element of the present invention, it is preferable that a hollow layer is provided on the inner surface of the through hole, and the through hole electrode and the core metal are insulated.
Further, the diameter of the through hole constituting the through hole electrode is preferably 1.0 mm or more.

  In the light-emitting element mounting enamel substrate of the present invention, it is preferable that a reflective cup-shaped recess is provided around the through-hole electrode.

  The present invention also provides a light emitting element module comprising a light emitting element mounted on the above-described light emitting element mounting hollow substrate according to the present invention.

  In the light emitting element module of the present invention, it is preferable that a plurality of light emitting elements are mounted on the through-hole electrode.

  In the light emitting element module of the present invention, the light emitting element may be sealed with a sealing resin including a phosphor that is excited by light emitted from the light emitting element and emits visible light having a different wavelength.

  Moreover, this invention provides the illuminating device which has the light emitting element module which concerns on this invention mentioned above.

  The present invention also provides a display device having the above-described light emitting element module according to the present invention.

  The present invention also provides a traffic signal device having the above-described light emitting device module according to the present invention.

Since the enamel substrate for mounting a light-emitting element of the present invention has a through-hole electrode in which a through hole provided in the enamel substrate is filled with a conductor, excellent heat dissipation is achieved when a light-emitting element is mounted on the through-hole electrode. can get. Further, it is possible to ensure insulation between the through-hole electrode and the enamel substrate.
Since the light emitting element module of the present invention is obtained by mounting the light emitting element on the through-hole electrode of the light emitting element mounting enamel substrate according to the present invention described above, the substrate electrode structure can be simplified and high density mounting is possible. . Further, since the through-hole electrode on which the light emitting element is mounted is insulated from the core metal by the enamel layer of the enamel substrate, sufficient electrical insulation can be ensured even with the through-hole electrode. Further, if the through-hole electrode is made of metal, sufficient heat dissipation can be secured, and a plurality of light-emitting elements can be concentrated and mounted on the through-hole electrode.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1A and 1B show a first embodiment of a light-emitting element module according to the present invention. FIG. 1A is a plan view of the light-emitting element module 10, and FIG. In the light emitting element module 10 of the present embodiment, a core metal 14 is covered with a hollow layer 15, a through hole 16 is formed in the center, and the through hole 16 is filled with a conductor such as metal. The light-emitting element mounting hollow substrate 13 (hereinafter referred to as a hollow substrate) provided with electrodes 17 is provided, and a plurality of light-emitting elements 11 are mounted on the through-hole electrodes 17 of the hollow substrate 13. .

  On one surface side of the hollow substrate 13, a substrate electrode 18A made of a conductor is provided along a desired circuit pattern. Further, on the back surface side of the hollow substrate 13, a back surface electrode 18 </ b> B that is connected to the through-hole electrode 17 that is a common electrode and extends to an appropriate position on the back surface of the substrate (for example, the periphery of the substrate) is provided.

  As the plurality of light emitting elements 11 mounted on the through hole electrode 17, the light emitting element 11 of the type having electrode terminals on both the upper and lower sides is used in this example, and the lower electrode terminal is soldered to the through hole electrode 17. It is fixed by die bonding using silver paste, and the through-hole electrode 17 and the lower electrode terminal are electrically connected. In addition, the upper electrode terminal of the light emitting element 11 is electrically connected to the substrate electrode 18 by a wire bond 12. The wire bond 12 is preferably a gold wire.

  The plurality of light emitting elements 11 mounted on the through-hole electrode 17 are collectively sealed with a sealing resin 19. The sealing resin 19 can be mixed with a phosphor that is excited by light emitted from the light emitting element 11 and emits visible light having a different wavelength.

  The conductor filled in the through hole 16 is preferably made of a metal such as silver, aluminum, or solder, but is not limited thereto. The shape of the through hole 16 is not limited to a circle, and may be a polygon or the like. The diameter of the through hole 16 is only required to allow the light emitting element 11 to be mounted, and can be appropriately set according to the size of the light emitting element 11 and the use of the light emitting element module 10.

  When the through-hole 16 is provided in the enamel substrate 13, the through-hole 16 is formed in advance in the core metal 14, and the enamel layer 15 is formed by baking glass on the entire surface of the core metal 14 with the through-hole. Since the inner surface of the through hole 16 is also insulated by the enamel layer 15, the through hole electrode 17 made of a metal such as silver, aluminum, or solder does not make electrical contact with the core metal 14.

  Next, a method for manufacturing the enamel substrate 13 will be described. For example, a low carbon steel plate is used as the core metal 14 and cut into a predetermined shape, and a through hole 16 having a predetermined diameter is formed at a position where the light emitting element 11 is disposed. Thereafter, the core metal 14 is suspended in a liquid in which a glass powder is dispersed in a suitable dispersion medium, and an electrode is disposed at a position facing the core metal 14, so that the glass is electrodeposited on the core metal 14. Further, the core metal 14 taken out is fired at a high temperature, and the glass is baked on the surface of the core metal 14. Next, using a silver paste for printing or the like, it is applied to the formation position of the substrate electrode 18A and the back electrode 18B, and baked to complete the enamel substrate 13. At this time, since the glass is electrodeposited inside the through hole 16 and fired, the inner surface of the through hole 16 is also insulated. Next, a metal material such as silver paste or solder is poured into the through hole 16 to form a through hole electrode 17 that is electrically connected to the back side of the substrate.

  Since the hollow substrate 13 has the through-hole electrode 17 in which the through-hole 16 is filled with a conductor, excellent heat dissipation can be obtained when the light-emitting element 11 is mounted on the through-hole electrode 17. Further, by providing the enamel layer 15 on the inner surface side of the through hole 16, electrical insulation between the through hole electrode 17 and the enamel substrate 13 can be secured.

  Next, mounting of the light emitting element 11 on the enamel substrate 13 with the through-hole electrode 17 manufactured as described above will be described. First, the light emitting elements 11 are die-bonded to the through-hole electrodes 17 of the enamel substrate 13 using a plurality of light emitting elements 11 by soldering, silver paste, or the like. Furthermore, the electrode terminal on the opposite side (upper side) of the light emitting element 11 is connected to the end of the substrate electrode 18A disposed around the through-hole electrode 17 by the wire bond 12, thereby establishing an electrical connection. Thereafter, the light emitting element 11 is covered and sealed with a sealing resin 19.

Since the light emitting element module 10 of the present embodiment has the light emitting element 11 mounted on the through-hole electrode 17 of the enamel substrate 13 described above, the electrode structure of the substrate can be simplified and high-density mounting becomes possible.
In addition, since the through-hole electrode 17 on which the light emitting element 11 is mounted is insulated from the core metal 14 by the enamel layer 15 of the enamel substrate 13, even the through-hole electrode 17 can sufficiently ensure electrical insulation.
Furthermore, by configuring the through-hole electrode 17 with a metal, sufficient heat dissipation can be ensured, and a plurality of light emitting elements 11 can be concentratedly mounted on the through-hole electrode 17.

  FIG. 2 is a view showing a second embodiment of the light emitting element module according to the present invention. The light emitting element module 20 of the present embodiment is configured to include substantially the same components as the light emitting element module 10 of the first embodiment shown in FIG. 1, and further has a reflective cup shape around the through-hole electrode 17 of the enamel substrate 13. It is characterized by providing a recess.

  In order to distribute the direction of light emitted from the light emitting element 11 to the front surface of the substrate, it is common in the mounting structure of the light emitting element module to form a reflective cup shape. In the case of the enamel substrate 13 for the light emitting element module 20, the reflection cup shape as shown in FIG. 2 can be produced. In this case, a reflecting cup shape and a through-hole 16 are formed in a predetermined position of the core metal 14 by machining such as drilling, and the core metal 14 is enameled, so that enameling as shown in FIG. The substrate 13 and the light emitting element module 20 can be manufactured. This recess can be filled with the sealing resin 19 after the light emitting element 11 is mounted.

  The enamel substrate 13 and the light emitting element module 20 of the present embodiment can obtain the same effects as those of the first example described above, and further, by providing a reflective cup-shaped recess around the through-hole electrode 17, the light emitting element 11. Can be efficiently distributed to the front side of the substrate.

  FIG. 3 is a diagram showing a third embodiment of the light emitting element module according to the present invention. The light emitting element module 30 of the present embodiment uses the same hollow substrate 13 as that used in the light emitting element module 10 of the first embodiment shown in FIG. 1, but both electrode terminals are on one side (upper surface or lower surface). The difference is that the light emitting element 11 is used. In this embodiment, both electrode terminals of the light-emitting element 11 are mounted on the through-hole electrode 17 with one electrode terminal facing upward, one electrode terminal is mounted on the substrate electrode 18A, and the other electrode terminal is mounted on the through-hole electrode 17, respectively. They are electrically connected by a bond 12. The light emitting element module 30 of the present embodiment can obtain the same effects as those of the first example described above.

  FIG. 4 is a view showing a fourth embodiment of the light emitting element module according to the present invention. The light emitting element module 40 of this embodiment uses the same hollow substrate 13 as that used in the light emitting element module 10 of the first embodiment shown in FIG. 1, but both electrode terminals are on one side (upper surface or lower surface). The difference is that the light emitting element 11 is used. In this embodiment, the flip-chip bonding structure in which both electrode terminals of the light emitting element 11 are faced downward, one electrode terminal is fixed to the substrate electrode 18A, and the other electrode terminal is fixed to the through-hole electrode 17 with conductive bonds 41, respectively. It has become. The light emitting element module 40 of the present embodiment can achieve the same effects as those of the first example described above, and can further eliminate the wire bonding process of the light emitting element 11, thereby improving productivity.

  The light emitting element used in the light emitting element module of the present invention is preferably an LED, but is not limited to this, and a semiconductor laser diode (LD) element, an organic EL element, or the like can also be used. The light emitting element can be selected from various light emitting elements whose emitted light ranges from visible light to ultraviolet light. For example, blue light emission and green light emission represented by gallium nitride compound semiconductors can be used. An element may be sufficient and the red light emitting element represented by GaP may be sufficient. It is also possible to manufacture a white LED module by mounting a blue LED on an enamel substrate and mixing a blue excited yellow light emitter with a sealing resin.

  In addition, the light emitting element module of the present invention has good heat dissipation of the substrate and high reliability during long-term lighting, and the enamel substrate used in the light emitting element module of the present invention has high mechanical rigidity. And a screw hole can be formed (refer to Japanese Patent Laid-Open No. 4-129287). Therefore, the light emitting element module of the present invention can be sufficiently applied to lighting devices, display devices, and traffic signals.

<Production of enamel substrate>
A 1.5-mm-thick low carbon steel plate was cut into a size of 10 × 50 mm, and a hole with a diameter of 3 mm was drilled at a position to be a through-hole electrode by machining with a drill to produce a core metal with a through-hole.
The core metal was suspended in a liquid obtained by putting glass powder in a dispersion medium and acidified, and an electrode was disposed at a position facing the core metal, so that the glass was electrodeposited on the core metal. Furthermore, the taken-out core metal was baked at high temperature, and glass was baked on the core metal surface. The through-hole inner diameter of the enamel substrate obtained after firing was 2.5 mm, and the thickness of the enamel layer of the entire substrate was 200 μm. Further, the through hole was filled with a silver paste to close the through hole, thereby forming a through hole electrode.
On the enamel substrate with through-hole electrodes, electrodes and electric circuits were screen printed with a silver paste and baked.

<Mounting of light emitting element>
On the through-hole electrode of the hollow substrate, a blue LED (gallium nitride compound semiconductor, a type in which electrode terminals are located on the upper and lower sides) as a light emitting element was mounted by silver paste. The other electrode terminal of the blue LED was connected to the substrate electrode by a wire bonding method using a gold wire with a diameter of 25 μm. Further, the blue LED was sealed with an epoxy resin to produce a light emitting element module having a structure shown in FIG.

  When an electric withstand voltage test was performed by applying a voltage of 1000 V between the electrodes of the obtained light emitting element module and the insulation against the core metal was examined, it was confirmed that there was no problem with the insulation in the test of n = 20.

<Examination of through-hole diameter>
In the same manner as the above-described enamel substrate production, enamel substrates with through-hole diameters changed to φ500 μm, φ1000 μm, and φ1500 μm as shown in Table 1 were produced, and the through-hole appearance of each enamel substrate was examined.

  As a result of producing a hollow layer by varying the hole diameter opened in the core metal, when the through-hole diameter was φ1000 μm or more (Examples 2 and 3), a through-hole electrode could be formed, but the through-hole diameter was 500 μm. In the case (Example 1), the hole was blocked with glass, and a through hole could not be made. For this reason, the through hole diameter is desirably φ1000 μm or more.

1A and 1B show a first embodiment of a light-emitting element module according to the present invention, in which FIG. It is sectional drawing which shows 2nd Embodiment of the light emitting element module of this invention. It is sectional drawing which shows 3rd Embodiment of the light emitting element module of this invention. It is sectional drawing which shows 4th Embodiment of the light emitting element module of this invention. The conventional light emitting element module is illustrated, (a) is a top view, (b) is sectional drawing. It is sectional drawing which shows an example of the conventional aluminum laminated substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 20, 30, 40 ... Light emitting element module, 11 ... Light emitting element, 12 ... Wire bond, 13 ... Hollow substrate, 14 ... Core metal, 15 ... Hollow layer, 16 ... Through hole, 17 ... Through hole electrode, 18A ... Substrate electrode, 18B ... back electrode, 19 ... sealing resin, 41 ... bond.

Claims (10)

  A hollow substrate for mounting a light-emitting element, wherein a through hole is provided in a hollow substrate in which a core metal is covered with a hollow layer, and a through hole electrode is formed by filling the through hole with a conductor.   The enamel substrate for mounting a light emitting device according to claim 1, wherein a hollow layer is provided on an inner surface of the through hole, and the through hole electrode and the core metal are insulated.   The hollow substrate for mounting a light-emitting element according to claim 2, wherein the through-hole has a diameter of φ1 mm or more.   The enamel substrate for mounting a light-emitting element according to claim 1, wherein a concave portion having a reflective cup shape is provided around the through-hole electrode.   5. A light emitting element module, wherein the light emitting element is mounted on the light emitting element mounting enamel substrate according to claim 1.   The light emitting element module according to claim 5, wherein a plurality of light emitting elements are mounted on the through-hole electrode.   The light emitting element module according to claim 5 or 6, wherein the light emitting element is sealed with a sealing resin containing a phosphor that is excited by light emitted from the light emitting element and emits visible light having a wavelength different from that.   The illuminating device which has a light emitting element module in any one of Claims 5-7.   The display apparatus which has a light emitting element module in any one of Claims 5-7. A traffic signal having the light emitting element module according to claim 5.

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