JP2003234513A - Resin for wavelength conversion light emitting diode to which fluorescent dye or fluorescent pigment is added - Google Patents

Abstract

(57) Abstract: To improve the visibility of a light-emitting diode having a light-emitting element made of a gallium nitride-based compound semiconductor material and to improve the luminance thereof. A wavelength-converting light-emitting diode resin to which a fluorescent dye or a fluorescent pigment for converting light from a light-emitting element that is a gallium nitride-based compound semiconductor stacked on an n-type and a p-type is added. The fluorescent dye or fluorescent pigment in the resin is excited by blue visible light from the light emitting element, emits visible light longer than the excitation wavelength, and improves the visibility of the light emitting diode. For a wavelength conversion light emitting diode to which a fluorescent dye or a fluorescent pigment is added.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode (hereinafter, referred to as an LED) in which a light emitting element is surrounded by a resin mold. The present invention relates to a wavelength conversion light emitting diode capable of emitting light and having high luminance. 2. Description of the Related Art Generally, an LED has a structure as shown in FIG. 1 is, for example, G cut into 1 mm square or less.
A light emitting element made of aAlAs, GaP, or the like, 2 is a metal stem, 3 is a metal post, and 4 is a resin mold surrounding the light emitting element. The back electrode of the light emitting element 1 is electrically connected to the metal stem 2 by bonding with a silver paste or the like.
The surface electrode of the light emitting element 1 is wire-bonded on its surface with a gold wire extended from a metal post 3 as another terminal,
Further, the light emitting element 1 is molded with a transparent resin mold 4. Usually, a resin having a high refractive index and high transparency is selected for the resin mold 4 in order to efficiently emit light emitted from the light emitting element into the air. In some cases, an inorganic pigment or an organic pigment is mixed as a colorant into the resin mold 4 for the purpose of converting the color or correcting the color. For example,
If a red pigment is added to the resin mold of the green light emitting device having a GaP semiconductor material, the emission color can be white. [0004] However, conventionally,
The technique of adding a colorant to a resin mold to convert the wavelength has hardly been put to practical use, and the technique of correcting the color with a colorant has been used only slightly. This is because the addition of a coloring agent, which is a non-light emitting substance that can convert the wavelength, to the resin mold greatly reduces the brightness of the LED itself. [0005] By the way, currently, LEDs that are put into practical use as LEDs are LEDs that emit infrared, red, yellow, and green light, and blue or ultraviolet LEDs have not yet been put into practical use. The blue and ultraviolet light emitting elements are II-VI group ZnS.
e, studies have been made using semiconductor materials such as SiC of the IV-IV group and GaN of the III-V group, and recently, among them, the general formula is GaxAll _-xN (where x is 0 ≦ x ≦ 1). The gallium nitride-based compound semiconductor represented by the formula (1) has been reported to exhibit relatively excellent light emission at room temperature, and has attracted attention. Also, an LED that realizes a pn junction for the first time using a gallium nitride-based compound semiconductor has been announced (Applied Physics, Vol. 60, No. 2, p163-p166, 199).
1). According to this, the emission wavelength of an LED having a pn junction gallium nitride-based compound semiconductor is mainly 430 nm.
And also has an emission peak in the ultraviolet region around 370 nm. The wavelength is the shortest wavelength among the semiconductor materials. However, the LED has an emission color close to purple as indicated by the emission wavelength, and thus has a disadvantage that visibility is poor. The present invention has been made in view of such circumstances, and an object of the present invention is to achieve a light emission peak of 430 n.
An object of the present invention is to improve the visibility of an LED having a light emitting element made of a gallium nitride-based compound semiconductor material in the vicinity of m and in the vicinity of 370 nm, and to improve its luminance. SUMMARY OF THE INVENTION The present invention relates to a wavelength-added fluorescent dye or fluorescent pigment for converting light from a light emitting device which is a gallium nitride-based compound semiconductor stacked in n-type and p-type. In the conversion light emitting diode resin, the fluorescent dye or the fluorescent pigment in the wavelength conversion light emitting diode resin,
A wavelength to which a fluorescent dye or a fluorescent pigment is added, which is excited by blue visible light from the light emitting element and emits visible light longer than the excitation wavelength to improve the visibility of the light emitting diode. Conversion light emitting diode resin. FIG. 2 is an embodiment showing the structure of an LED according to the present invention. 11 is GaAs on a sapphire substrate
a blue light-emitting element in which 1N is stacked in n-type and p-type,
Reference numerals 2 and 3 denote a metal stem and a metal post as in FIG. 1, and reference numeral 4 denotes a resin mold surrounding the light emitting element. Since the back surface of the light emitting element 11 is an insulating substrate of sapphire and electrodes cannot be taken out from the back surface, the GaAlN layer is etched to expose the surface of the n-type layer to electrically connect the n electrode of the GaAlN layer to the metal stem 2. Then, a method of attaching an ohmic electrode and electrically connecting it with a gold wire has been adopted. The other electrodes are wire-bonded on the surface of the p-type layer by gold wires extending from the metal posts 3 as in FIG. Further, a fluorescent dye 5 which emits at a wavelength having an emission peak at 480 nm when excited by a wavelength around 420 to 440 nm is added to the resin mold 4. The fluorescent dye and the fluorescent pigment are generally excited by light having a short wavelength, and emit light having a wavelength longer than the excitation wavelength. Conversely, some fluorescent pigments emit short-wavelength light when excited by long-wavelength light, but they have very poor energy efficiency and emit only weakly. As described above, a gallium nitride-based compound semiconductor has an emission peak on the shortest wavelength side in a semiconductor material used for an LED,
Moreover, it has an emission peak also in the ultraviolet region. Therefore, when it is used as a material of a light emitting element, the fluorescent substance can be most preferably excited by adding a fluorescent dye or a fluorescent pigment to a resin mold surrounding the light emitting element. Therefore, it goes without saying that it is possible to convert light of various wavelengths depending on the type of fluorescent dye or fluorescent pigment, not to mention color correction of the blue LED. Further, since short-wavelength light is converted into long-wavelength light and energy efficiency is high, only a small amount of fluorescent dye or fluorescent pigment needs to be added, which is very advantageous from the viewpoint of lowering luminance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view showing the structure of a conventional LED. FIG. 2 is a schematic sectional view showing the structure of an embodiment of the LED of the present invention. [Description of Signs] 11 ... Light-emitting element 2 ... Metal stem 3 ... Metal post 4 ... Resin mold 5 ... Fluorescent dye.

Claims (1)

Claims: 1. A wavelength-converting light-emitting diode resin to which a fluorescent dye or a fluorescent pigment for converting light from a light-emitting element that is a gallium nitride-based compound semiconductor laminated on an n-type and a p-type is added. In, the fluorescent dye or fluorescent pigment in the wavelength conversion light emitting diode resin is excited by blue visible light from the light emitting element, emits visible light longer wavelength than the excitation wavelength to improve the visibility of the light emitting diode A resin for a wavelength conversion light-emitting diode to which a fluorescent dye or a fluorescent pigment has been added.