JP3393089B2 - Light emitting diode - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a wavelength conversion type light emitting diode, and more particularly to a type which converts blue light emission into white light. 2. Description of the Related Art Conventionally, as this kind of wavelength conversion type light emitting diode, for example, the one shown in FIG. 12 is known (Japanese Patent No. 2990928). This is a lead frame type light emitting diode 1, in which a concave portion 3 is provided in one metal stem 2 of the lead frame, and a light emitting diode element 4 made of a gallium nitride-based compound semiconductor is mounted on the concave portion 3 and fixed. The light emitting diode element 4 is connected to the metal stem 2 and the other metal post 5 of the lead frame by bonding wires 6 and 7, respectively, and the whole is sealed with a bullet-shaped transparent resin 9. A fluorescent material 8 for wavelength conversion is dispersed in the transparent resin 9, and when the light emitting diode 1 is turned on, light emitted from the light emitting diode element 4 hits the fluorescent material 8 and is converted into a yellow color to emit light. A white light emission color can be obtained by mixing with the original blue light emission of the diode element 4. [0003] However, in the above-mentioned conventional light emitting diode 1, the fluorescent material 8 is dispersed in the transparent resin 9 which seals the light emitting diode element 4. For this reason, there is a problem that the transmittance of light passing through the transparent resin 9 decreases, and the luminance of white light emission decreases. Further, since the specific gravity of the fluorescent material 8 is larger than that of the transparent resin 9, it is difficult to uniformly disperse the fluorescent material 8, and the chromaticity varies not only between different light emitting diodes but also within one light emitting diode. There was a problem. SUMMARY OF THE INVENTION It is an object of the present invention to provide a light emitting diode in which emission luminance is improved and chromaticity variation is suppressed. [0006] In order to solve the above-mentioned problems, a light-emitting diode according to claim 1 of the present invention comprises a substrate
Together through the fluorescent material-containing layer for fixing the back surface of the light emitting diode element on an upper surface, the upper surface of the light emitting diode element in the resin sealed comprising light emitting diodes, the substrate top surface
For filling the fluorescent material-containing layer into the provided thin plate electrode
Open a hole and make thin contact with the upper surface of the base material formed on the inner peripheral edge of the hole.
Check the slight difference between the plate electrode and the thickness of the phosphor-containing layer.
While maintaining the weir to maintain
The projection surface is formed . [0010] The present invention provides the following. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a light emitting diode according to the present invention will be described in detail with reference to the accompanying drawings.
1 to 3 show an embodiment in which the present invention is applied to a surface-mounted light emitting diode. A surface-mounted light emitting diode 11 according to this embodiment has a rectangular glass epoxy substrate (hereinafter, referred to as a glass epoxy substrate) 12 serving as a base material.
A pair of electrodes (cathode electrode 13 and anode electrode 14)
Are formed in a pattern, and the lower surfaces of the electrodes 13 and 14 are fixed to printed wirings 16 and 17 on a motherboard 15 with solder 18 to realize surface mounting. A light emitting diode element 20 is mounted on the center of the upper surface of the glass epoxy substrate 12, and is fixed to the glass epoxy substrate 12 by a fluorescent material containing layer 21 applied on the back surface thereof. The light-emitting diode element 20 is a blue light-emitting element made of a gallium nitride-based compound semiconductor, and has a structure in which an n-type semiconductor 23 and a p-type semiconductor 24 are grown on an upper surface of a sapphire substrate 22, as shown in FIG. The n-type semiconductor 23 and the p-type semiconductor 24 have electrodes 25 and 26, and the bonding wires 2 are connected to the cathode electrode 13 and the anode electrode 14 provided on the glass epoxy substrate 12.
Blue light is emitted by being connected by 7, 28. On the other hand, as shown in FIG. 3, the fluorescent material containing layer 21 provided on the back side of the light emitting diode element 20 has:
An appropriate amount of the fluorescent material 30 is uniformly dispersed in the adhesive 29 as a base. This is applied to the upper surface of the glass epoxy substrate 12 so as to have a predetermined thickness, and the light emitting diode element 20 is placed thereon. When the adhesive 29 is solidified by heating, the back surface of the light emitting diode element 20 is fixed to the upper surface of the glass epoxy substrate 12. Since a strong adhesive force is obtained between the adhesive 29 and the glass epoxy substrate 12, the fluorescent material-containing layer 21 does not peel off. The fluorescent material 30 is a light emitting diode element 2
It is excited by luminescence energy from 0 to convert short-wavelength visible light into long-wavelength visible light. For example, a fluorescent substance such as an yttrium compound is used. Therefore, in the above embodiment, the light emitted from the boundary surface between the n-type semiconductor 23 and the p-type semiconductor 24 of the light emitting diode element 20 emits blue light 31 upward, sideward and downward.
In particular, the blue light 31 emitted downward is excited by hitting the fluorescent material 30 dispersed in the fluorescent material containing layer 21, is converted into a yellow light 32, and emits light in all directions. Then, the yellow light 32 mixes with the blue light 31 emitted above and to the side of the light emitting diode element 20, and white light is obtained when the light emitting diode 11 is viewed. The upper part of the light emitting diode element 20 is protected by a rectangular parallelepiped resin sealing body 33, and the blue light 31 and the wavelength-converted yellow light 32 travel straight through the resin sealing body 33. As a main component, a transparent resin is used, and since it does not contain a fluorescent material unlike the related art, the light transmittance is good, and as a result, the luminance of mixed white light emission is increased. Further, in this embodiment, since the fluorescent material 30 is dispersed in the adhesive 29, unlike the conventional method, the fluorescent material 30 is dispersed in the resin sealing body. There is no occurrence of bias, and variation in chromaticity during light emission can be suppressed. Further, in this embodiment, since the fluorescent material containing layer 21 is far away from the upper surface of the resin sealing body 33 and is hidden on the back side of the light emitting diode element 20, the structure is hardly affected by ultraviolet rays. . By mixing a diffusing agent such as silicon dioxide into the resin sealing body 33, more uniform light emission can be obtained. A thin film layer having high reflectivity such as copper foil or aluminum foil is provided on the back side of the fluorescent material-containing layer 21 or, as shown in FIG.
Is formed, and the light emitting diode element 20 is fixed on the mounting surface 35 via the fluorescent material-containing layer 21, so that the reflection efficiency of light emitted below the light emitting diode element 20 can be increased. . Further, the resin sealing body 33 for protecting the upper part of the light emitting diode element 29 is not limited to the above-described rectangular parallelepiped shape, but as shown in FIG.
4 can also be formed. By forming the lens portion 34, it is possible to expect an increase in light emission luminance due to a light condensing effect. In addition, as shown in FIG.
By making the auxiliary fluorescent material-containing layer 36 thin on the horizontal upper surface of 3, the color can be adjusted on the upper surface. The auxiliary fluorescent material-containing layer 36 is formed by dispersing the yttrium-based fluorescent material 30 or another fluorescent material in an organic solvent, and is printed on the upper surface of the resin sealing body 33 as a coating material or in a sheet shape. The formed one may be attached. Auxiliary fluorescent material containing layer 36
Is formed thin, the resin sealing body 3
3 can minimize the decrease in light transmittance. FIGS. 7 and 8 show a second embodiment of the present invention. In this embodiment, the cathode electrode 13 is used.
A square hole 37 slightly smaller than the planar shape of the light emitting diode element 20 is formed in the mounting surface 35 extended from
7 is filled with the fluorescent material-containing layer 21, on which the light emitting diode element 20 is mounted and fixed. The other configuration is the same as that of the first embodiment. In this embodiment, when the fluorescent material-containing layer 21 is filled in the square hole 37, the inner peripheral edge of the square hole 37 functions as a weir 38 to prevent the fluorescent material-containing layer 21 from flowing out. The thickness can be secured, and a uniform thickness can be secured over the entire lower surface of the light emitting diode element 20. In addition, the weir 38 for securing the predetermined thickness is not limited to the mounting part 35 which forms a part of the cathode electrode 13. FIG. 9 shows a third embodiment of the present invention. Unlike the above embodiment, the adhesive 29 and the fluorescent material 30 are separated and the fluorescent material 3 is placed in a transparent organic solvent.
The fluorescent material-containing coating material 40 in which 0 is dispersed is applied to the glass epoxy substrate 12.
Is formed by applying a print on the upper surface of the substrate and forming it to a predetermined thickness by overprinting or the like. After the fluorescent material-containing coating material 40 is dried, a transparent adhesive 29 is applied thereon, and the light emitting diode element 20 is placed and fixed thereon. In this embodiment, the blue light emitted to the lower surface side of the light emitting diode element 12 passes through the adhesive 29, hits the fluorescent material 30 dispersed in the fluorescent material-containing paint 40, is excited, and is converted into yellow light. The fluorescent material-containing paint 40 emits light in all directions.
Has a merit that it is easy to adjust the degree of color mixing with blue light emission because the thickness of the light emitting element can be made large and the thickness can be easily adjusted. The fluorescent material-containing paint 40
Alternatively, it can be formed by attaching a phosphor-containing sheet. FIG. 10 shows a fourth embodiment of the present invention. In this embodiment, a cylindrical reflection frame 41 is disposed at the center of the upper surface of the glass epoxy substrate 12, and the light-emitting diode element 20 is mounted therein. The reflecting frame 41 has a tapered inner peripheral wall 42, and the light emitting diode element 2
It has the function of reflecting the 0 light emission on the inner peripheral wall 42 and condensing it upward. The light emitting diode element 20 is fixed to the upper surface of the glass epoxy substrate 12 via a fluorescent material containing layer 21 in which a fluorescent material 30 is dispersed in an adhesive 29, as in FIG. The reflection effect can be further enhanced by providing a reflection layer on the back surface side of the fluorescent material containing layer 21. Further, similarly to the above-described embodiment, it is also possible to separate the adhesive and the fluorescent material of the fluorescent material containing layer 21 and form them in separate layers. FIG. 11 shows a fifth embodiment of the present invention. As a substrate on which the light emitting diode element 20 is mounted, a thin metal substrate 4 is used instead of the glass epoxy substrate 12.
5 is used. In this embodiment, a mortar-shaped recess 46 is press-formed at the center of the metal substrate 45, and an adhesive 29 is formed on the bottom surface 47 of the recess 46 in the same manner as in the first embodiment.
The back surface of the light emitting diode element is fixed via a fluorescent material containing layer 21 in which a fluorescent material 30 is dispersed. Recess 46
The inner peripheral wall 48 has a tapered surface as in the previous embodiment, and has a structure capable of increasing the reflection efficiency.
In this embodiment, since the metal substrate 45 itself has conductivity and can serve as an electrode, the bonding wires 27 and 28 are used.
Is connected to the upper surface of the metal substrate 45. The slit 49 and the insulating tape 50 provided on the metal substrate 45 are:
It is for separating the cathode electrode 13 side and the anode electrode 14 side. In addition, the rear side of the metal substrate 45 is reinforced by a resin 51 to secure rigidity. In each of the above-described embodiments, as shown in FIG.
Although a chip type light emitting diode directly surface mounted on 7 has been described, the light emitting diode of the present invention can also be applied to the lead frame type described in the conventional example. That is, an adhesive containing a fluorescent material is applied to the concave portion of the metal stem on which the light emitting diode element is mounted, and the light emitting diode element made of a gallium nitride-based compound semiconductor is fixed thereon, thereby forming a shell-shaped resin seal. High-luminance white light emission can be obtained without dispersing the fluorescent material in the stationary body. In each of the above embodiments, the case where the light emitting diode element 20 and the pair of electrodes 13 and 14 are connected by the bonding wires 27 and 28 has been described. However, the present invention is not limited to this. Connection methods such as flip chip mounting using solder bumps are also included. As described above, according to the light emitting diode of the present invention, the phosphor-containing layer is disposed on the back surface side of the light emitting diode element to convert the wavelength of the light emitted by the light emitting diode element. Since it is performed on the back side of the light emitting diode element, it is not necessary to disperse the fluorescent material for wavelength conversion in the resin sealing body protecting the upper side of the light emitting diode element. Therefore, there is an effect that the light transmittance of the resin sealing body is increased as compared with the case where the fluorescent material is dispersed, and the light emission luminance of the light emitting diode can be increased. Ma
According to the light emitting diode of the present invention,
For filling the fluorescent material-containing layer in the thin plate electrode provided on the surface
A hole for the base material formed on the inner periphery of the hole
The slight difference between the thickness of the phosphor-containing layer and the thickness of the phosphor-containing layer
The fluorescent material containing layer is
It is said that the thickness can be secured and the thickness can be controlled.
Has an effect. Furthermore, in the light emitting diode according to the present invention,
According to the above, on the thin plate electrode on which the fluorescent material containing layer is disposed
Since the reflective surface is formed on the surface,
After the yellow emission can be efficiently reflected upward.
Color mixing with blue light emission
To play. Further, according to the light emitting diode of the present invention, it is not necessary to disperse the fluorescent material in the resin body for sealing the upper part of the light emitting diode element. The dispersion of the fluorescent material is not biased, and the variation in chromaticity can be suppressed between individual light emitting diodes or even within one light emitting diode. According to the light emitting diode of the present invention, since the fluorescent material is dispersed in the adhesive, the fluorescent material can be arranged together in the step of bonding the light emitting diode elements. This is also advantageous. Further, according to the light emitting diode of the present invention, a dome-shaped lens portion is formed on the upper surface of the resin sealing member for sealing the upper part of the light emitting diode element to collect light, By providing a tapered surface having a light condensing effect around the element, the luminance of white light emission can be further increased. According to the light emitting diode of the present invention, since the auxiliary fluorescent-containing layer is provided on the upper surface of the resin sealing body for sealing the upper part of the light emitting diode element, color adjustment on the upper surface can be achieved. It becomes possible. The light emitting diode according to the present invention is most suitable as a chip type light emitting diode of a surface mount type and has a structure excellent in mass productivity.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a first embodiment of a light emitting diode according to the present invention. FIG. 2 is a sectional view taken along line AA in FIG. 1 when the light emitting diode is mounted on a motherboard. FIG. 3 is a diagram showing the principle of wavelength conversion on the back side of the light emitting diode element in the light emitting diode. FIG. 4 is a perspective view of a light-emitting diode when a light-emitting diode element is mounted on a reflective layer that is a part of a cathode electrode. FIG. 5 is a cross-sectional view of a light emitting diode when a dome-shaped lens portion is formed on a sealing resin body. FIG. 6 is a cross-sectional view of a light emitting diode when an auxiliary phosphor-containing layer is formed on an upper surface of a sealing resin body. FIG. 7 is a partial perspective view showing the vicinity of a part of a cathode electrode provided with a weir in a second embodiment of the light emitting diode according to the present invention. FIG. 8 is a sectional view of a light emitting diode according to the second embodiment. FIG. 9 is a cross-sectional view of a light-emitting diode according to a third embodiment of the present invention, in which an adhesive layer and a phosphor-containing layer are separated into a two-layer structure. FIG. 10 is a sectional view of a light-emitting diode according to a fourth embodiment of the present invention, in which a reflection frame is provided around a light-emitting diode element. FIG. 11 is a cross-sectional view of a light emitting diode according to a fifth embodiment of the present invention when a thin metal substrate is used. FIG. 12 is a sectional view showing an example of a conventional wavelength conversion type light emitting diode. [Description of Signs] 11 Light-emitting diode 12 Glass epoxy substrate (base material) 13 Cathode electrode 14 Anode electrode 15 Mother board 20 Light-emitting diode element 21 Fluorescent material containing layer 29 Adhesive 30 Fluorescent material 33 Resin sealing body 34 Lens part 36 Auxiliary fluorescent material Content layer 37 Square hole 38 Weir 40 Fluorescent material-containing paint 41 Reflection frame 45 Metal substrate (base material) 48 Inner peripheral wall

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-10-163526 (JP, A) JP-A-11-68166 (JP, A) JP-A-11-68169 (JP, A) JP-A-10-168 151794 (JP, A) JP-A-5-63239 (JP, A) JP-A-11-46019 (JP, A) JP-A-11-87784 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 33/00 H01L 21/52 H01L 23/29 H01L 23/31 JICST file (JOIS)

Claims (1)

(57) [Claim 1] A light emitting device in which the back surface of a light emitting diode element is fixed to the upper surface of a base material via a phosphor-containing layer and the upper surface side of the light emitting diode element is resin-sealed. In the diode, a fluorescent material-containing layer is provided on a thin plate electrode provided on the upper surface of the base material.
Open a hole for filling, formed on the inner periphery of this hole
The slight difference between the upper surface of the substrate and the thin plate electrode
While the weir is used to secure the thickness of the layered structure,
A light-emitting diode having a reflective surface formed on an upper surface of an electrode .