JP2001298216A - Surface-mounting semiconductor light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-mounting semiconductor light-emitting device having a high light-emitting efficiency and capable of being a smaller and thinner shape. SOLUTION: This semiconductor light-emitting device comprises a mounting substrate 1 for surface mounting having a pair of outer electrodes 1a, 1b, a light-transparent substrate 2a, a flip-chip light-emitting element 2 bonded on the mounting substrate 1 by connecting the element to the outer electrodes 1a, 1b, a wavelength conversion layer 4 that coverts whole body of the light- emitting element 2 and converts the emitted-light wavelength of the light- emitting element 2 to that of a fluorescent substance contained therein, and a resin package 5 that covers whole body of the wavelength conversion layer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device in which light emitted by a blue light emitting diode is converted into a wavelength to obtain white light, for example. The present invention relates to a surface-mounted semiconductor light emitting device that can be manufactured.

[0002]

2. Description of the Related Art Light emitting diodes emitting blue light (hereinafter referred to as "L").
ED ”) recently became GaN, GaAl
By using GaN-based compound semiconductors such as N, InGaN, and InAlGaN, products with high emission luminance can be obtained. And this blue (B) LED
With the combination of the conventional red (R) and green (G) light emitting LEDs, a high-quality full-color image using three of these LEDs as one dot can be formed.

In the field of LEDs, since R, G, and B of three primary colors of light are required for full color, further development and improvement of LEDs of these luminescent colors are mainly performed. On the other hand, attempts have already been made to achieve white light emission that can be obtained only by combining R, G, and B with a single LED. One of such attempts is disclosed in, for example, JP-A-11-40858. This involves forming a pair of external electrodes on an insulating substrate, bonding the p-side and n-side electrodes formed on the upper surface of the light-emitting chip mounted on the substrate to the external electrodes with wires, and further forming the fluorescent electrodes formed by the sedimentation method. The upper surface of the light emitting chip is coated with a material coating layer.
Then, by conducting the external electrodes of the substrate to the electrodes of the printed wiring board and conducting surface mounting, white light can be obtained from the light from the upper surface of the light emitting chip by wavelength conversion by the phosphor coating layer. That is, in the case of a blue light-emitting chip using a GaN-based compound semiconductor, a color mixture of its own blue light-emitting component and a yellow-green component wavelength-converted by the fluorescent substance contained in the fluorescent substance coating layer is used. White light emission is obtained.

[0004]

However, in the semiconductor light emitting device described in the above publication, a phosphor coating layer is formed only on the upper surface of the light emitting chip by a sedimentation method.
Light emitted from the upper surface of the light emitting chip is easily converted to white light. However, the efficiency of wavelength conversion for light traveling toward the side surface or the bottom surface of the light emitting chip becomes poor, and it is difficult to obtain pure white light emission. In order to prevent this, the side and bottom surfaces of the light emitting chip may be sealed with a non-light transmitting package. However, in that case, a part of the light emitting component from the active layer does not contribute to external light emission, and the light emission efficiency decreases.

[0005] Further, since the p-side and n-side electrodes of the light emitting chip and the external electrodes have a conductive structure bonded by wires, it is necessary to perform molding including the bulk of the wires. For this reason, the height of the product after mounting on a substrate and molding and the distance between external electrodes are increased, and there is a limit to the reduction in size and thickness of the product.

As described above, the conventional surface-mounted semiconductor light emitting device that obtains light emission such as white light by wavelength conversion has a problem that the light emission efficiency is reduced and the device cannot cope with a reduction in size and thickness.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a surface-mount type semiconductor light emitting device which has high luminous efficiency and can be made small and thin.

[0008]

A surface-mounted semiconductor light emitting device according to the present invention comprises a mounting substrate for surface mounting provided with a pair of external electrodes, and a flip-chip type provided with a light-transmitting substrate. A light-emitting element that is electrically connected to the mounting substrate and is fixed to the mounting substrate; a wavelength conversion layer that covers the entire light-emitting element and converts the emission wavelength of the light-emitting element with a contained fluorescent substance; and a resin that covers the entire wavelength conversion layer. And a package. The wavelength conversion layer in the present invention is obtained by mixing YAG-based phosphor particles into an epoxy resin conventionally used in the field of LED lamps.

According to the present invention, a surface-mounted semiconductor light-emitting device having high luminous efficiency and capable of being reduced in size and thickness can be obtained.

[0010] In the above structure, the particle size of the fluorescent substance in the wavelength conversion layer may be equal to or larger than the thickness of the bump electrode for flip chip connection. In this configuration,
The gap between the light emitting element and the mounting substrate, that is, the gap generated by the bump electrode can be completely filled with the epoxy resin component, which is one of the components of the wavelength conversion layer, and the reliability of bonding by the bump electrode can be improved.

Further, a uniform corrugated pattern may be formed on the entire surface of the wavelength conversion layer, and the surface of the pattern may be used as a sealing interface with the resin package.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1, wherein a mounting substrate for surface mounting having a pair of external electrodes, and a light-transmitting substrate is provided as a flip-chip type and is electrically connected to the external electrodes. A light-emitting element fixed to a mounting substrate, a wavelength conversion layer that covers the entire light-emitting element and converts the emission wavelength of the light-emitting element with a contained fluorescent substance, and a resin package that covers the entire wavelength conversion layer. This is a surface-mount type semiconductor light-emitting device characterized by the following features: it can be made small and thin, and has the effect of increasing the luminous efficiency of wavelength-converted light.

According to a second aspect of the present invention, the particle size of the fluorescent substance in the wavelength conversion layer is equal to or larger than the thickness of the bump electrode for flip chip connection. The gap between the light emitting element and the mounting board, that is, the gap generated by the bump electrode can be completely filled with the epoxy resin component, which is one of the components of the wavelength conversion layer, and the reliability of the bonding by the bump electrode is improved. Has the effect of increasing.

According to a third aspect of the present invention, a uniform wavy uneven pattern is formed on the entire surface of the wavelength conversion layer, and the surface of the uneven pattern is used as a sealing interface with the resin package. The surface-mounted semiconductor light emitting device according to claim 1 or 2, wherein the semiconductor light emitting device has a function of emitting wavelength-converted light more uniformly and improving a bonding strength at an interface.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic longitudinal sectional view of a surface mount type semiconductor light emitting device according to an embodiment of the present invention, and FIG. 2 is a plan view.

In FIG. 1, external electrodes 1a and 1b are formed at both ends of an insulating mounting substrate 1 from the bottom side to the back side, and are electrically connected to these external electrodes 1a and 1b to form GaN.
A blue light emitting element 2 using a system compound semiconductor is mounted. The mounting board 1 is surface-mounted by making the external electrodes 1a and 1b conductive to a wiring pattern of a printed wiring board such as an electronic device.

The blue light-emitting element 2 using a GaN-based compound semiconductor has a structure in which, for example, an n-type layer of GaN, an active layer of InGaN, and a p-type layer of GaN are stacked on the surface of a substrate 2a made of sapphire. It is. Then, as is well known in the art, a part of the p-type layer is etched to expose the n-type layer, an n-side electrode 2b is formed on the exposed surface of the n-type layer, and a p-type electrode is formed on the surface of the p-type layer. This is a so-called flip chip type in which the side electrode 2c is formed. n-side electrode 2b
The bump electrodes 3a and 3b are formed in advance on the p-side electrode 2c, respectively, and the light emitting element 2 is attracted by vacuum, and these bump electrodes 3a and 3b are joined to the external electrodes 1a and 1b to be conductively fixed. Is done.

The periphery of the light emitting element 2 including its bottom surface is sealed with a wavelength conversion layer 4, and the periphery of the wavelength conversion layer 4 is sealed with a resin package 5 made of epoxy resin.
The wavelength conversion layer 4 is obtained by mixing a fluorescent substance for converting blue light emission of the light emitting element 2 into white light into epoxy resin. The fluorescent substance for converting the blue light emission to the white light emission may be any substance having a complementary color relationship with the blue color which is the light emission color of the light emitting element 2, and a fluorescent dye, a fluorescent pigment, a fluorescent substance, or the like can be used. , Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce
Etc. are preferred.

Here, the wavelength conversion layer 4 converts blue light emission from the light emitting element 2 into white light emission, and the conversion efficiency depends on the thickness of the wavelength conversion layer 4. That is, when the wavelength conversion layer 4 is thicker than a predetermined value, a greenish emission color is obtained, and when the wavelength conversion layer 4 is thinner than the predetermined value, bluish light is emitted. It is easy to be. Therefore, it is preferable that the thickness of the wavelength conversion layer 4 is the same in all directions of the light emitting element 2 and is set so that white light can be converted with optimal efficiency.

In brief, the manufacturing method will be described. The pattern of the external electrodes 1a and 1b is formed by plating on a substrate material in a wafer state, and then the light emitting element 2 is mounted and mounted, and the wavelength conversion layer 4 is formed by screen printing. Form. Then, the resin package 5 may be formed on the surface of the substrate material by a molding method, and may be formed by dicing into the planar shape of FIG.

In the above configuration, when the light emitting element 2 is energized, light is emitted from the active layer. In this case, in the blue light emitting element 2 of the GaN-based compound semiconductor using the transparent sapphire substrate 2a, although the upper surface of the substrate 2a is used as the main light extraction surface, the bottom and side surfaces of the semiconductor thin film layer laminated on the substrate 2a Also emit light, and the entire surface of the light emitting element 2 emits light almost uniformly. Then, the light from the light emitting element 2 is converted into a white wavelength while passing through the wavelength conversion layer 4 containing a fluorescent substance, and emits external light.

The light emitting element 2 is mounted on the mounting substrate 1 such that a gap is formed between the external electrodes 1a and 1b by the bump electrodes 3a and 3b, and the resin of the wavelength conversion layer 4 enters the gap. .

As described above, by covering the entire light emitting element 2 with the wavelength conversion layer 4, light emitted from all directions of the light emitting element 2 can be converted to white light to emit light. Luminous efficiency can be improved.

The light emitting element 2 is of a flip-chip type and has bump electrodes 3a, 3b on the mounting substrate 1 for external electrodes 1a,
1b, the dimensions in the height direction and the external electrodes 1a, 1b are smaller than in the case of wire bonding.
Can be shortened. Therefore, the size and thickness of the light emitting element 2 can be reduced, and the field of application to electronic devices can be expanded. Further, since no bonding wire is included, the production is simplified and the light emission directivity can be expanded, so that white light emission with higher luminance than that of the conventional example can be obtained.

By the way, the wavelength conversion layer 4 is conventionally made of an LED.
Epoxy resins used in the field of lamps include YAG phosphor particles such as (Y, Gd) ₃ (Al, Ga).
₅ O ₁₂ : It is composed of a paste mixed with Ce or the like and having thixotropy so as to be suitable for screen printing. When the wavelength conversion layer 4 is coated around the light emitting element 2 by the screen printing method, if the YAG-based phosphor particles are smaller than the thickness of the bump electrodes 3a and 3b, the phosphor particles will be formed between the light emitting element 2 and the mounting substrate 1. It may be filled in between and may reduce the strength of flip chip bonding. This is because the function as an adhesive between the light emitting element 2 and the mounting substrate 1 cannot be expected since the wavelength conversion layer 4 cured after printing has a phosphor component of 80% or more. Also,
The flow resistance of the phosphor particles between the light emitting element 2 and the mounting substrate 1 is large, and an unfilled portion may occur.

On the other hand, by setting the particle size of the fluorescent substance to be equal to or greater than the thickness of the bump electrodes 3a and 3b, the light emitting element 2
The gap between the substrate and the mounting substrate 1 can be completely filled only with the epoxy resin, which is one of the constituent elements of the wavelength conversion layer 4, and a highly reliable flip chip bonding can be obtained due to the effect of the epoxy resin as an adhesive.

FIG. 3 shows an example in which the surface of the wavelength conversion layer has a uniform wave shape, and the same components as those shown in FIGS. 1 and 2 are designated by the same reference numerals.

As shown in an enlarged manner in FIG. 3, a fine wavy uneven pattern 4a is formed on the entire surface of the wavelength conversion layer 4. The uneven pattern 4a is engraved in a direction perpendicular to the drawing, and appears as a horizontal stripe on the entire surface of the wavelength conversion layer 4. By forming such an uneven pattern 4a, reflection and diffusion of light passing through the wavelength conversion layer 4 are promoted.
Therefore, even if the wavelength conversion layer 4 cannot be formed with high precision and uniform thickness around the light emitting element 2, uniform white light can be emitted from the entire wavelength conversion layer 4 and light emission without color unevenness can be obtained. Is obtained.

Further, since the area of the contact interface of the resin package 5 can be increased by forming the concavo-convex pattern 4a, the bonding degree of the interface can be further strengthened. Therefore, the difference in the refractive index between the wavelength conversion layer 4 and the resin package 5 can be made uniform in all directions, and light emission without chromaticity difference can be obtained.

[0031]

According to the present invention, the light emitting device is flip-chip type and is conductively fixed on the mounting substrate, and the periphery of the light emitting device is sealed with the wavelength conversion layer. Can be made smaller and thinner,
The field of application to electronic equipment is expanded. In addition, since the entire surface of the light emitting element is sealed by the wavelength conversion layer, light from the light emitting element can be efficiently extracted, and emission luminance is improved.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a surface-mounted semiconductor light emitting device according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of the semiconductor light emitting device of FIG.

FIG. 3 is a schematic longitudinal sectional view of a semiconductor light emitting device in which a surface of a wavelength conversion layer has a wavy shape.

[Explanation of symbols]

 Reference Signs List 1 mounting board 1a, 1b external electrode 2 light emitting element 2a substrate 2b n-side electrode 2c p-side electrode 3a, 3b bump electrode 4 wavelength conversion layer 4a uneven pattern 5 resin package

Claims (3)

[Claims] 1. A mounting substrate for surface mounting having a pair of external electrodes, a light emitting element having a light transmissive substrate and being fixed to the mounting substrate by conducting to the external electrodes as a flip-chip type, and A surface-mounted semiconductor light-emitting device comprising: a wavelength conversion layer that covers the entire element and converts the emission wavelength of the light-emitting element with a contained fluorescent substance; and a resin package that covers the entire wavelength conversion layer. . 2. The surface-mounted semiconductor light emitting device according to claim 1, wherein the particle size of the fluorescent substance in the wavelength conversion layer is equal to or larger than the thickness of the bump electrode for flip chip connection. 3. The method according to claim 1, wherein a uniform corrugated pattern is formed on the entire surface of the wavelength conversion layer, and the surface of the pattern is a sealing interface with the resin package.
Or a surface-mounted semiconductor light-emitting device according to item 2.