JP2008270728A - Light emitting device and lighting device - Google Patents

Abstract

The light emitting device includes a base, a plurality of mounting pads, and a plurality of light emitting elements. The light emitting device 1 further includes a plurality of external terminals 14 and a plurality of bonding pads 15. The plurality of mounting pads 12 are provided on the upper surface of the base body 11. The plurality of light emitting elements 13 are mounted on the upper surface of the base 11 and are electrically connected to the plurality of mounting pads 12. The plurality of external terminals 14 are electrically connected to the plurality of mounting pads 12. The plurality of bonding pads 15 are provided on the lower surface of the base 11 and are arranged corresponding to the plurality of mounting pads 12.
[Selection] Figure 6

Description

  The present invention relates to a light emitting device and a lighting device having a light emitting element such as a light emitting diode.

In recent years, for example, in the illumination field, development of a light-emitting device having a light-emitting element has been advanced. For example, a lighting device including a light emitting element is required to further improve the light emission characteristics. As one example for improving the light emission characteristics of a lighting device or the like, there is improving the accuracy of the mounting position of the light emitting device with respect to the mounting substrate.
JP 2003-31849 A

  As one example for improving the accuracy of the mounting position of the light emitting device, there is a reduction in the positional deviation of the light emitting device during reflow of the bonding material for fixing the light emitting device and the mounting substrate. An object of the present invention is to improve the accuracy of the mounting position of a light emitting device.

  According to one aspect of the present invention, a light emitting device includes a base, a plurality of mounting pads, and a plurality of light emitting elements. The light emitting device further includes a plurality of external terminals and a plurality of bonding pads. The substrate has an upper surface and a lower surface. The plurality of mounting pads are provided on the upper surface. The plurality of light emitting elements are mounted on the upper surface of the base and are electrically connected to the plurality of mounting pads. The plurality of external terminals are electrically connected to the plurality of mounting pads. The plurality of bonding pads are provided on the lower surface of the base and are arranged corresponding to the plurality of mounting pads.

  According to another aspect of the present invention, the lighting device includes a mounting substrate, a plurality of fixed pads, and a plurality of light emitting devices. The plurality of fixed pads are provided on the mounting substrate. The light emitting device is mounted on a mounting substrate and bonded to a plurality of fixed pads. The light emitting device includes a base, a plurality of mounting pads, and a plurality of light emitting elements. The light emitting device further includes a plurality of external terminals and a plurality of bonding pads. The substrate has an upper surface and a lower surface. The plurality of mounting pads are provided on the upper surface. The plurality of light emitting elements are mounted on the upper surface of the base and are electrically connected to the plurality of mounting pads. The plurality of light emitting elements are electrically connected to the plurality of mounting pads. The plurality of bonding pads are provided on the lower surface of the base and are arranged corresponding to the plurality of mounting pads. The plurality of bonding pads are bonded to the plurality of fixed pads.

  According to one aspect of the present invention, the light emitting device has a plurality of bonding pads arranged corresponding to the plurality of mounting pads, so that the accuracy of the mounting position is improved. Therefore, for example, the light emission characteristics of the lighting device are improved.

  According to another aspect of the present invention, the lighting device has a plurality of bonding pads that are arranged corresponding to the plurality of mounting pads and bonded to the plurality of fixed pads of the mounting substrate, thereby emitting light. The accuracy of the mounting position of the device is improved. Therefore, the light emission characteristics of the lighting device are improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As illustrated in FIG. 1, the lighting device 100 includes a plurality of light emitting devices 1, a mounting substrate 2, and a cover 3. The plurality of light emitting devices 1 are mounted on the mounting substrate 2. As illustrated in FIG. 2, the lighting device 100 further includes a constant current circuit 4. The constant current circuit 4 is electrically connected to the plurality of light emitting devices 1.

  As illustrated in FIG. 3, the lighting device 100 includes a plurality of fixed pads 5 provided on the upper surface of the mounting substrate 2. The light emitting device 1 is bonded to a plurality of fixed pads 5.

  As shown in FIGS. 4 to 6, the light emitting device 1 includes a base 11, a plurality of mounting pads 12, and a plurality of light emitting elements 13. The light emitting device 1 further includes a plurality of external terminals 14 and a plurality of bonding pads 15. In FIG. 4, the light emitting device 1 is mounted on the xy plane of a virtual xyz space. The xyz coordinates are orthogonal coordinates. In FIG. 5, the light emitting element 13 is shown through.

  The base 11 has an upper surface (first surface) 11-1 and a lower surface (second surface) 11-2. The base 11 is made of an insulating material. An example of the insulating material is ceramics. The ceramic is selected from the group consisting of an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, and a glass ceramic. Another example of the insulating material is a resin. The resin is an epoxy resin or a liquid crystal polymer (PLC).

  As shown in FIG. 7, the plurality of mounting pads 12 are provided on the upper surface 11-1 of the base body 11. One mounting pad 12 includes a first conductor pattern 12-1 and a second conductor pattern 12-2. The plurality of mounting pads 12 are arranged symmetrically with respect to the optical axis 70. As shown in FIG. 8, the optical axis 70 refers to an axis orthogonal to the virtual plane 80 at a point 81 of the virtual plane 80. The virtual plane 80 is a plane parallel to the virtual xy plane on which the light emitting device 1 is mounted. A point 81 is a point having the highest luminous intensity [unit: cd] in the virtual plane 80. In FIG. 8, the virtual plane 80 is, for example, 15 cm away from the light emitting device 1.

  The plurality of light emitting elements 13 are mounted on the upper surface 11-1 of the base 11 and are electrically connected to the plurality of mounting pads 12. The light emitting element 13 is a light emitting diode made of a semiconductor material. The light emitting element 13 is formed of a plurality of semiconductor layers including an active layer. The light emitting element 13 has a p electrode and an n electrode. The p electrode is electrically connected to the first conductor pattern 12-1. The n electrode is electrically connected to the second conductor pattern 12-2. A power supply voltage (VDD) is applied to the p-electrode. A reference voltage is applied to the n electrode. The reference voltage is a ground voltage (GND). The light emitting element 13 is a light source that emits primary light by driving power. The primary light is included in the UV wavelength region and the blue wavelength region, or partially overlaps these wavelength regions.

  The plurality of external terminals 14 are provided on the lower surface 11-2 of the base 11 and are electrically connected to the plurality of mounting pads 12. The plurality of external terminals 14 are arranged symmetrically with respect to the optical axis 70.

  The plurality of bonding pads 15 are provided on the lower surface 11-2 of the base body 11. As shown in FIG. 9, the plurality of bonding pads 15 are arranged corresponding to the plurality of mounting pads 12. “Corresponding” means that the plurality of bonding pads 15 are provided directly below the plurality of mounting pads 12 and are partially provided on the lower surface 11-2 of the substrate 11. In FIG. 9, the mounting pad 12 is shown through. The plurality of bonding pads 15 are disposed between each of the plurality of external terminals 14. The number of the plurality of bonding pads 15 is equal to the number of the plurality of mounting pads 12. The bonding pad 15 is made of the same material as the mounting pad 12. The bonding pad 15 has the same dimensions as the fixed pad 5. As shown in FIG. 10, the plurality of bonding pads 15 are arranged symmetrically with respect to the optical axis 70. The position where the bonding pad 15 is disposed is indicated by reference numeral 15-1.

  The bonding pad 15 is fixed to the fixing pad 5 formed on the mounting substrate 2 by a bonding material made of a metal material. The material of the bonding material is made of a gold-tin (Au-Sn) alloy, a tin-silver (Sn-Ag) alloy, a tin-silver-copper (Sn-Ag-Cu) alloy, and tin-lead (Sn-Pb). Selected from the group.

  When the light emitting device 1 is mounted on the mounting substrate 2, a bonding material is provided between the bonding pad 15 and the fixed pad 5. The bonding material is softened by being subjected to heat treatment at a temperature included in a range of 150 ° C. to 350 ° C. The softened bonding material is cured by being cooled. In this way, the light emitting device 1 is mounted on the mounting substrate 2.

  The light emitting device 1 of the present embodiment has a plurality of bonding pads 15 arranged corresponding to the plurality of mounting pads 12, so that when mounted on the mounting substrate 2, the mounting position shift amount is reduced. Has been reduced.

  Another example of the bond pad 15 is described with reference to FIG. The bonding pad 15 has a curved shape. The bonding pad has a circular shape.

  The light emitting device 1 includes an encapsulating layer 16, a light emitting member 17, and a reflecting member 18. The encapsulating layer 16 is attached to the surface of the light emitting element 13. The encapsulating layer 16 is made of a translucent material. “Translucency” of the encapsulating layer 16 means that at least a part of the wavelength of the primary light emitted from the light emitting element 13 is transmitted. The translucent material is selected from the group consisting of silicone resin, epoxy resin, acrylic resin, fluorine resin, polycarbonate resin and polyimide resin. The translucent material is preferably a silicone resin in consideration of resistance to the primary light emitted from the light emitting element. The encapsulating layer 16 is provided in a region defined by the reflecting member 18.

  The light emitting member 17 is provided above the plurality of light emitting elements 13. The light emitting member 17 covers the plurality of light emitting elements 13. The light emitting member 17 includes a fluorescent material that is excited by the primary light emitted from the light emitting element 13. The fluorescent material is embedded in the matrix material. The matrix material has translucency. “Translucent” of the matrix material means that at least a part of the wavelength of the light emitted from the light emitting element 13 is transmitted. The light emitted from the fluorescent material passes through the matrix material. An example of the matrix material is a silicone resin. An air gap 19 is provided between the encapsulating layer 16 and the light emitting member 17.

  The reflection member 18 is provided on the base 11. An example of the material of the reflecting member 18 is an insulating material. The insulating material is ceramic or resin. Another example of the material of the reflecting member 18 is metal. The metal is selected from the group consisting of aluminum (Al), silver (Ag), gold (Au), platinum (Pt), titanium (Ti), chromium (Cr), copper (Cu) and rhodium (Rh).

  As shown in FIG. 12, the power supply voltage (VDD) is applied to one external terminal 14-1 of the light emitting device 1. The external terminal 14-1 is an anode terminal. A reference voltage is applied to the other external terminal 14-2. The external terminal 14-2 is a cathode terminal. A reference voltage is applied to the plurality of bonding pads 15. The reference voltage is a ground voltage (GND).

  Hereinafter, another embodiment of the present invention will be described with reference to FIG. The illumination device of the present embodiment is different from the illumination device 100 shown in FIG. 1 in that the dimension of the fixed pad 5 is different from the dimension of the bonding pad 15. The dimension of the fixed pad 5 is larger than the dimension of the bonding pad 15. The area of the fixed pad 5 is larger than the area of the bonding pad 15. The fixed pad 5 covers the bonding pad 15.

  As shown in FIG. 14, the bonding pad 15 is fixed to the fixing pad 5 by the bonding material 6. The bonding material 6 is, for example, a gold-tin (Sn—Au) alloy. The bonding material 6 becomes a molten state by heat treatment. The light emitting device 1 is fixed to the mounting substrate 2 by curing the molten bonding material 6. In the illuminating device of the present embodiment, since the fixed pad 5 has a size larger than the bonding pad 15, the accuracy of the mounting position of the light emitting device 1 is improved. Therefore, the light emission characteristics of the lighting device are improved.

  The bonding material 6 spreads toward the mounting substrate 2. Therefore, the heat dissipation characteristics in the lighting device are improved. Since the bonding material 6 spreads toward the mounting substrate 2, voids in the bonding material 6 are reduced. The bonding strength of the light emitting device 1 to the mounting substrate 2 is improved.

The molten bonding material 6 is described with reference to FIG. In FIG. 14, symbol γ _L indicates the surface tension of the bonding material. A symbol γ _SL indicates an interfacial tension between the fixed pad 5 and the bonding material 6. Symbol γ _S indicates the surface tension of the fixed pad 5. In these γ _L , γ _SL and γ _S , the following relationship is established.
γ _S −γ _SL = γ _L cos θ
The angle θ is a contact angle of the bonding material 6.

In the present embodiment, the contact angle θ becomes smaller due to the difference in dimensions between the fixed pad 5 and the bonding pad 15. When the contact angle θ is smaller, the resultant force of the surface tension γ _L and the interfacial tension γ _SL of the bonding material becomes larger. Accordingly, the force toward the center of the fixed pad 5 is increased. The force acting in the center direction on the bonding pad 15 located on the bonding material 6 is increased. The bonding pad 15 is drawn to the center of the bonding material 6 by self-alignment and placed at a desired position. Therefore, the accuracy of the mounting position of the light emitting device 1 is improved.

  The bonding material in the embodiment shown in FIGS. 1 and 13 is described with reference to FIG. The curing start temperature of the first bonding material 6 attached to the plurality of fixed pads 5 and the plurality of bonding pads 15 is set to cure the second bonding material 8 attached to the plurality of terminal pads 7 and the plurality of external terminals 14. Higher than the starting temperature. At the time of cooling after reflow of the bonding materials 6 and 8, the bonding material 6 starts to be cured before the bonding material 8. Therefore, the mounting position of the light emitting device 1 is adjusted using the surface tension in the bonding material 6.

1 shows an illumination device 100 according to an embodiment of the present invention. The structure of the illuminating device 100 is shown. The mounting board | substrate 2 shown by FIG. 1 is shown. The light-emitting device 1 shown by FIG. 1 is shown. The top view of the light-emitting device 1 is shown. 1 shows a longitudinal sectional view of a light emitting device 1. The top view of the base | substrate 11 shown by FIG. 4 is shown. The optical axis 70 of the light-emitting device 1 is shown. A bottom view of the substrate 11 is shown. An arrangement of a plurality of bonding pads 15 is shown. The other example of the bonding pad is shown. The circuit diagram of the light-emitting device 1 is shown. The illuminating device of other embodiment of this invention is shown. 2 shows a junction structure of a light emitting device. 2 shows a junction structure of a light emitting device. The joining structure is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting device 11 Base | substrate 12 Mounting pad 13 Light emitting element 14 External terminal 15 Bonding pad 16 Encapsulation layer 17 Light emitting member 18 Reflective member 2 Mounting board 5 Fixing pad

Claims (14)

A substrate having an upper surface and a lower surface;
A plurality of mounting pads provided on the upper surface;
A plurality of light emitting elements that are electrically connected to the plurality of mounting pads and are mounted on the top surface of the base;
A plurality of external terminals electrically connected to the plurality of mounting pads;
A plurality of bonding pads provided on the lower surface of the base body and disposed corresponding to the plurality of mounting pads;
A light emitting device comprising:   The light emitting device according to claim 1, wherein the plurality of bonding pads are disposed between each of the plurality of external terminals.   The light emitting device according to claim 2, wherein the plurality of bonding pads are arranged symmetrically with respect to the optical axis.   4. The light emitting device according to claim 3, wherein the plurality of external terminals are arranged symmetrically with respect to the optical axis.   The light emitting device according to claim 1, wherein the number of the plurality of bonding pads is equal to the number of the plurality of mounting pads.   The light emitting device according to claim 1, wherein each of the plurality of bonding pads has a curved shape.   The light emitting device according to claim 6, wherein each of the plurality of bonding pads has a circular shape.   The light emitting device according to claim 1, wherein the plurality of bonding pads are made of the same material as the plurality of mounting pads.   The light emitting device according to claim 1, wherein a reference voltage is applied to the plurality of bonding pads.   The light emitting device according to claim 9, wherein the reference voltage is a voltage applied to the light emitting element.   The light-emitting device according to claim 10, wherein the reference voltage is a ground voltage. A mounting board;
A plurality of fixed pads provided on the mounting substrate;
A light emitting device that is bonded to the plurality of fixed pads and is mounted on the mounting substrate; and
The light emitting device is
A substrate having an upper surface and a lower surface;
A plurality of mounting pads provided on the upper surface;
A plurality of light emitting elements that are electrically connected to the plurality of mounting pads and are mounted on the top surface of the base;
A plurality of external terminals electrically connected to the plurality of mounting pads;
A lighting device comprising: a plurality of bonding pads provided on the lower surface of the base body and disposed corresponding to the plurality of mounting pads and bonded to the plurality of fixed pads.   The lighting device according to claim 12, wherein each of the plurality of fixing pads has a size larger than each of the plurality of bonding pads. A plurality of terminal pads electrically connected to the plurality of external terminals and provided on the mounting substrate;
The curing start temperature of the first bonding material attached to the plurality of fixed pads and the plurality of bonding pads is the curing start temperature of the second bonding material attached to the plurality of terminal pads and the plurality of external terminals. The lighting device according to claim 12, wherein the lighting device is higher.

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