JP2015062261A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a light-emitting device capable of suppressing discoloration or the like of a reflection film and maintaining high output.SOLUTION: A manufacturing method of a light-emitting device sequentially includes: a conductive member preparation step of preparing a conductive member 1 having a reflection film 1b; a light-emitting device disposition step of disposing a light-emitting device 3 on the reflection film; and a protective film formation step of forming a protective film 5 on the reflection film by an atomic layer deposition method.

Description

  The present invention relates to a light emitting device in which a light emitting element is provided on a conductive member.

  In a light-emitting device using a light-emitting element as a light source, a reflective film containing silver or the like is provided around the light-emitting element to improve output, and a protective film made of an inorganic material is formed on the reflective film by sputtering, CVD, or the like. Attempts have been made to suppress discoloration of the reflective film (for example, Patent Document 1).

JP2009-224538A

  However, in the conventional method, although the output can be once improved by the reflection film, there is a problem that the output is lowered during use. That is, in sputtering, CVD, etc., a protective film is formed when the material component hits the target with a certain degree of straightness. For example, in the vicinity of the light emitting element, the light emitting element itself becomes an obstacle and forms a high quality protective film. I couldn't. For this reason, there is a problem that the reflective film deteriorates and discolors preferentially from those portions as time passes.

  In view of the above, an object of the present invention is to provide a method for manufacturing a light emitting device capable of suppressing discoloration of a reflective film and maintaining high output.

  A method of manufacturing a light emitting device according to an embodiment includes a conductive member preparing step of preparing a conductive member including a reflective film, a light emitting element arranging step of arranging a light emitting element on the reflective film, and an atomic layer deposition method on the reflective film. And a protective film forming step of forming a protective film in order.

  A method for manufacturing a light emitting device according to another embodiment includes a conductive member preparing step of preparing a conductive member, a light emitting element arranging step of arranging a light emitting element on the conductive member, and electrically connecting the conductive member and the light emitting element with a wire. Wire connecting step for connecting the conductive member, a reflective film forming step for forming a reflective film on the surface of the conductive member and the wire, and a protective film forming step for forming a protective film on the surface of the reflective film by atomic layer deposition. Have.

Drawing 1 is a mimetic diagram for explaining a manufacturing method of a light emitting device of one embodiment. FIG. 2 is an enlarged view of a broken line frame in FIG. FIG. 3 is a schematic diagram for explaining a method for manufacturing a light emitting device according to another embodiment. FIG. 4 is a view for explaining the operational effects of the method for manufacturing a light emitting device according to an embodiment.

  A mode for carrying out the present invention will be described below with reference to the drawings. However, the form shown below illustrates the manufacturing method of the light-emitting device for actualizing the technical idea of this invention, Comprising: This invention is not limited to the following. In addition, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation.

[Embodiment 1]
1A to 1F show each step of the method for manufacturing the light emitting device of the present embodiment. FIG. 2 is an enlarged schematic view of a broken-line frame portion in FIG.

(Conductive member preparation process)
First, as shown in FIG. 1A, a conductive member 1 having a reflective film 1b provided on a base material 1a is prepared (conductive member preparation step). Here, not only the base material 1a but also the reflective film 1b has conductivity. In the present embodiment, the conductive member is composed of a base material and a reflective film.

  The base material 1a should just have electroconductivity, The material is not limited. As the base material 1a, for example, copper or a copper alloy can be used.

  The reflective film 1b only needs to reflect the light from the light emitting element 3, and the material thereof is not limited. As the reflective film 1b, for example, silver or aluminum can be used, and a material containing silver having a particularly high reflectance is preferable.

  1B to 1F, for convenience of explanation, the base material 1a and the reflective film 1b are not individually illustrated, and they are collectively referred to as the conductive member 1. In addition, the conductive member may be composed only of the reflective film, or another member may be interposed between the base material 1a and the reflective film 1b. Furthermore, the reflective film 1b does not need to be formed on the entire surface of the base material 1a, and may be formed, for example, in a region in the vicinity of the light emitting element 3 (region A (FIG. 2)).

(Package formation process)
Next, as shown in FIG. 1B, for example, a package 2 having a base 2a and a side wall 2b can be formed on the conductive member 1 (package forming step).

  There is no limitation on the material of the package, and it can be formed of, for example, resin or ceramic. In the case of a package made of resin, the package 2 is formed integrally with the conductive member 1 by placing the conductive member 1 in a package forming mold (not shown) and pouring and hardening the resin as the package material there. Can do. A part of the conductive member 1 is exposed on the bottom surface of the recess of the package.

  The package 2 is formed integrally with the conductive member 1 and its material is not limited as long as it is insulative. As the material of the package 2, an electrically insulating material having excellent light resistance and heat resistance is suitably used. For example, a thermoplastic resin such as polyphthalamide, a thermosetting resin such as an epoxy resin, glass epoxy, or ceramics is used. Can be used. In the present embodiment, the package 2 has the side wall 2b. However, the side wall is not necessarily provided.

(Light emitting element arrangement process)
Next, as shown in FIG.1 (c), the light emitting element 3 is arrange | positioned on the reflective film 1b (light emitting element arrangement | positioning process). Specifically, the light emitting element 3 can be disposed on the reflective film 1b via an adhesive member (not shown). The adhesive member may be conductive or insulative.

  The adhesive member is for arranging and fixing the light emitting element 3 on the conductive member 1, and the material thereof is not particularly limited. For example, when the adhesive member 3 is made insulating, an epoxy resin or a silicone resin can be used. When the adhesive member 3 is made conductive, an Au—Sn alloy, a SnAgCu alloy, a SnPb alloy, an InSn alloy, Ag, Sn and Ag can be used.

The light-emitting element 3 may be a known, for example, blue light emission and green light emission can be a nitride semiconductor _{(In X Al Y Ga 1-} X-Y N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) It can be set as LED which consists of.

(Wire connection process)
Next, as shown in FIG.1 (d), the light emitting element 3 and the reflecting film 1b can also be electrically connected with the electroconductive wire 4 (wire connection process). Here, the light emitting element 3 and the base material 1a are electrically connected via the conductive reflective film 1b.

  When the light emitting element 3 has a pair of electrodes on the same surface side (not shown) and the light emitting element 3 is disposed with the side facing up (the light emission observation surface side), as shown in FIG. Each wire 4 is also required. In this case, if the conductive member side of the light emitting element 3 has an insulating property, the adhesive member does not necessarily need to be an insulating member, and may be a conductive member such as a metal in consideration of thermal conductivity. . As another form, when the light emitting element has electrodes on both sides opposite to each other, one electrode is energized through a conductive adhesive member, so that one wire is sufficient. On the other hand, when the light emitting element has a pair of electrodes on the same surface side, and the light emitting element is disposed with the side facing down (opposite side to the light emission observation surface side (side facing the conductive member 1)), Since the electrodes can be energized through conductive adhesive members, no wires are required.

  The wire 4 is for electrically connecting the light emitting element 3 and the base material 1a, and the material is not limited. As the material of the wire 4, for example, a material containing at least one of gold, copper, platinum, aluminum, and silver can be used.

(Protective film formation process)
Next, as shown in FIG. 1E, a protective film 5 is formed on the reflective film 1b by an atomic layer deposition method (hereinafter also simply referred to as “ALD” (Atomic Layer Deposition)). That is, the protective film 5 is formed from the emission observation surface side. Unlike conventional methods such as sputtering, ALD is a method in which a layer of reaction components is formed for each atomic layer. The case where a protective film of aluminum oxide (Al ₂ O ₃ ) is formed using TMA (trimethylaluminum) and water (H ₂ O) will be described below.

First, TMA gas is introduced to react the OH groups on the surface of the reflective film, which is the target, with TMA (first reaction). Next, the surplus gas is exhausted. Thereafter, H ₂ O gas is introduced to react TMA bonded to the OH group in the first reaction with H ₂ O (second reaction). Next, the surplus gas is exhausted. Then, by repeating the first reaction, exhaust, second reaction, and exhaust as one cycle, Al ₂ O ₃ having a predetermined film thickness can be formed.

  Unlike sputtering, CVD, and the like, ALD has low rectilinearity of the reaction component, so that even in the vicinity of an obstacle, the reaction component is supplied equally and a reaction component is formed for each monomolecular layer. As a result, a high-quality protective film can be formed with a more uniform film thickness and film quality in the area in the vicinity of the obstacle as in the other areas without the obstacle.

  The protective film obtained by ALD is superior in quality and protective power as compared with the protective film obtained by the conventional method. Therefore, although the protective film obtained by the conventional method is partially discolored at a certain rate even in an area without an obstacle, the protective film obtained by ALD is hardly discolored regardless of the presence or absence of an obstacle. can not see. Furthermore, even if the protective film obtained by ALD is thin, the reflective film can be sufficiently protected, so that the protective film can be formed thinner than the protective film obtained by the conventional method. Accordingly, since light absorption in the protective film can be suppressed, a light emitting device with high light output in the initial characteristics can be obtained.

  When the protective film 5 is formed after the light emitting element 3 is disposed, the conventional method has a problem that the light emitting element 3 itself becomes an obstacle, and the material component of the protective film 5 does not reach the vicinity in the vicinity. As a result, the quality of the protective film 5 was lowered or the film thickness was reduced, and the reflective film in the area near the light emitting element 3 (area A (FIG. 2)) was deteriorated and discolored. The portion where the quality of the protective film is lowered has more pinholes than the other portions, and it is considered that the reflective film is sulphurized, brominated, etc., causing discoloration. Since the light output is strong in the vicinity of the light emitting element, the light output of the light emitting device is greatly reduced due to the discoloration of the reflective film in the vicinity of the light emitting element.

  Therefore, by employing ALD, the protective film 5 having excellent film quality and the like can be formed even in the region (region A (FIG. 2)) in the vicinity of the light emitting element. Thereby, discoloration etc. of the reflective film 1b in the area | region A can be suppressed.

  In particular, in a cross-sectional view, when the adhesive member is located only on the inner side of the light emitting element without reaching the side of the light emitting element, a gap is formed between the peripheral edge of the bottom surface of the light emitting element and the reflective film. Even in such a case, according to ALD, a protective film can also be formed on the reflective film in the gap.

  When the protective film is formed by the conventional method after the wire connecting step, due to the presence of the wire 4 (the wire 4 becomes an obstacle), the reflective film 1b below the wire 4 has sufficient material components of the protective film 5 There was a problem of not reaching. As a result, the quality of the protective film 5 deteriorates or the film thickness decreases, and the reflective film 1b in that portion is discolored. In particular, in the region near the connecting portion between the wire 4 and the reflective film 1b (region B (FIG. 2)) in the lower region of the wire 4, the conventional method not only changes the color of the reflective film 1b but also the reflective film 1b. There was also a problem that the wire 4 was eventually broken due to corrosion.

However, in the case of ALD, the protective film 5 having excellent film quality and the like can be formed even in the region immediately below the wire 4 (particularly, the region B (FIG. 2)). Thereby, deterioration of the protective film in the region B can be reduced, and not only discoloration and the like, but also cutting of the wire can be suppressed.
FIG. 4 shows a photograph of the vicinity of the connecting portion between the wire and the reflective film taken from the light emission observation surface side after the protective film forming step. 4A shows a 30 μm-thick protective film made of Al ₂ O ₃ by ALD, and FIG. 4B shows a 30 μm-thick protective film made of Al ₂ O ₃ by conventional sputtering. A film is formed. These photographs were taken after a certain period of time in a state of excessive sulfur component so that the reflective film made of Ag is easily sulfided (both are tests under the same conditions). As shown in FIG. 4 (a), the protective film formed by ALD is not only in the area free of obstacles away from the wire, but also in the area directly under the wire (in the area B in FIG. No change in color due to sulfuration was observed. On the other hand, as shown in FIG. 4 (b), the protective film formed by sputtering is discolored in many points even in an area free from obstacles away from the wire, and includes a wire including an area directly under the wire. The area around the connection with the reflective film was discolored continuously (the connection between the wire and the reflective film had fine irregularities on the wire, which became an obstacle. It is thought that not only the area but also the entire periphery of the connection part has changed color.) From these experimental results, it can be understood that an excellent protective film can be formed by forming a protective film by ALD.
In order to improve the light output as the light emitting device, for example, using a wire made of a material containing silver having a high reflectance, light reflection can be effectively performed by the wire. However, just as the reflective film changes color, the color change of the wire made of a material containing silver becomes a problem. Even in such a case, if it is ALD, a protective film can be formed on the entire surface of the wire from the light emission observation surface side to the opposite side (reflection film side) for the above reason. Etc. can be effectively suppressed.

  When a protective film is formed by a conventional method after the package formation process, due to the presence of the side wall of the package 2 (the package side wall becomes an obstacle), in the vicinity of the side wall of the concave portion made of the side wall (region C (FIG. 2)). There was a problem that the material component of the protective film 5 did not reach the surface sufficiently. As a result, the quality of the protective film 5 deteriorates or the film thickness decreases, and the reflective film 1b in that portion is discolored. The discoloration of the reflective film 1b in the vicinity of the side wall of the package 2 is a problem that cannot be ignored although the output is not as bad as the discoloration of the reflective film 1b in the region A.

  Therefore, by employing ALD, it is possible to form the protective film 5 having excellent film quality and the like even in the region (region C (FIG. 2)) near the side wall 2b. Thereby, since the discoloration of the reflecting film 1b in the region C can be suppressed, it is possible to further reduce the decrease in light output as the light emitting device.

  When the reflective film 1b contains silver, it is advantageous in that the reflectance is high, but the conventional method has a problem that the reflective film is discolored with the passage of time and the output tends to decrease. However, it is preferable to form a protective film by ALD because even if the reflective film is a material containing silver, discoloration and the like can be effectively prevented.

As the protective film 5, for example, aluminum oxide (Al ₂ O ₃ ) silicon dioxide (SiO ₂ ), aluminum nitride (AlN), or silicon nitride (Si ₃ N ₄ ) can be employed, preferably aluminum oxide or It can be silicon, more preferably aluminum oxide. Thereby, absorption of the light from a light emitting element is suppressed, and it can be set as the protective film excellent in protective power.

  The thickness of the protective film 5 can be 1 nm or more and less than 50 nm, preferably 2 nm or more and less than 25 nm, more preferably 3 nm or more and less than 10 nm. Accordingly, light absorption from the light emitting element can be suppressed while maintaining the function as a protective film, and a light emitting element with high output can be obtained.

  In FIG. 1E and the like, the protective film 5 is formed not only on the bottom surface of the recess of the package 2 but also on the upper surface and inner wall of the side wall 2b. It can also be done. A region where the protective film 5 is not formed can also be partially provided on the bottom surface of the recess of the package 2.

(Other processes)
As shown in FIG.1 (f), the sealing member 6 can be formed inside the recessed part which consists of the side wall 2b of a package as needed (sealing member formation process). Further, after cutting the conductive member 1 so that each functions as a light emitting device (conductive member cutting step), the conductive member 1 is bent to the back surface of the package 2 as necessary (conductive member bending step). It can be.

  The sealing member 6 is for sealing the light emitting element 3, and the material is not limited as long as it transmits the light from the light emitting element 3 to the outside. As a material of the sealing member 6, for example, a silicone resin, an epoxy resin, or the like can be used. Further, the sealing member 6 may contain a fluorescent member that emits light by light from the light emitting element 3. A known member can be used as the fluorescent member. When the light emitting element 3 emits blue light, a YAG phosphor, a TAG phosphor, a strontium silicate phosphor, etc. that emits yellow light can be used. As a whole, white light can be obtained.

[Embodiment 2]
The present embodiment will be described with reference to FIG. In addition, the same number is used about the member similar to Embodiment 1, and the overlapping description is abbreviate | omitted.

(Conductive member preparation process)
First, as shown in FIG. 3A, the conductive member 1 is prepared (conductive member preparation step). In the present embodiment, unlike Embodiment 1, only the base material is used as the conductive member, and the reflective film 1b is not provided at this stage.

(Package formation process)
Next, as shown in FIG. 3B, the package 2 having the base 2a and the side wall 2b can be formed on the conductive member 1 (package forming step).

(Light emitting element arrangement process)
Next, as shown in FIG.3 (c), the light emitting element 3 is arrange | positioned on the electrically-conductive member 1 (light emitting element arrangement | positioning process). Specifically, the light emitting element 3 can be arranged on the conductive member 1 through an adhesive member (not shown).

(Wire connection process)
Next, as shown in FIG.3 (d), the electrically-conductive member 1 and the light emitting element 3 are electrically connected with the electroconductive wire 4 (wire connection process).

(Reflective film formation process)
Next, the reflective film 1b is formed on the surfaces of the conductive member 1 and the wire 4 (reflective film forming step). For convenience of drawing, the reflective film 1b is not shown on the surface of the wire 4 in FIG. 3E. However, in the present embodiment, the reflective film 1b is not only applied to the surface of the conductive member 1 but also to the surface of the wire 4. Is formed. The reflective film 1 b also covers the joint portion between the conductive member 1 and the wire 4.

  Thereby, since the light absorption in the surface of the wire 4 can be suppressed, it can be set as the light-emitting device with higher output.

  As a method for forming the reflective film 1b, an existing method can be employed. In particular, in the case of electroplating, the reflective film 1b is selectively formed on the surfaces of the conductive member 1 and the wires 4 without forming a reflective film (metal film) on the surface of the light emitting element 3 that is not a conductor. Can do. The material of the reflective film 1b is the same as that of the first embodiment and can be silver or the like.

(Protective film formation process)
Next, as shown in FIG. 3F, a protective film 5 is formed on the surface of the reflective film 1b by ALD. For convenience of drawing, the protective film 5 is not shown on the surface of the wire 4 in FIG. 3 (f). However, in the present embodiment, the protective film 5 is actually provided on the surface of the wire 4 via the reflective film 1b. Is formed.

(Other processes)
As shown in FIG. 3G, the sealing member 6 can be formed inside the concave portion formed of the side wall 2b of the package as necessary (sealing member forming step). Further, after cutting the conductive member 1 so that each functions as a light emitting device (conductive member cutting step), the conductive member 1 is bent to the back surface of the package 2 as necessary (conductive member bending step). It can be.

  The light emitting device manufacturing method according to the present invention includes various light emitting device manufacturing methods such as illumination light sources, various indicator light sources, in-vehicle light sources, display light sources, liquid crystal backlight light sources, sensor light sources, and traffic lights. Can be used.

DESCRIPTION OF SYMBOLS 1 ... Conductive member 1a ... Base material 1b ... Reflective film 2 ... Package 2a ... Base part 2b ... Side wall 3 ... Light emitting element 4 ... Wire 5 ... Protective film 6 ... Sealing member

Claims (9)

A conductive member provided with a reflective film;
A light emitting device mounted on the reflective film;
A light-emitting device having a protective film that continuously covers the surface of the light-emitting element and the surface of the reflective film,
A light-emitting device in which the thickness of the protective film formed on the reflective film in the vicinity of the mounted light-emitting element is substantially equal to the thickness of the protective film formed on the surface of the reflective film excluding the vicinity of the light-emitting element.   The light emitting element and the reflective film are wire-bonded, and the protective film is formed to fill a gap formed between a wire end connected to the reflective film and the reflective film. Item 4. The light emitting device according to Item 1.   The light emitting device according to claim 2, wherein the protective film is formed to have substantially the same thickness on the reflective film around the wire end.   4. The light emitting device according to claim 2, wherein the thickness of the protective film formed in the vicinity of the wire end is substantially equal to the thickness of the protective film formed on the surface of the reflective film excluding the vicinity of the wire end. . A package having a base and sidewalls is formed on the conductive member;
The light emitting device according to claim 1, wherein a thickness of the protective film formed in the vicinity of the side wall is substantially equal to a thickness of the protective film formed on the surface of the reflective film excluding the vicinity of the side wall.   The light-emitting device according to claim 5, wherein the protective film is formed on the entire surface of the wire.   The light emitting device according to claim 1, wherein the reflective film contains silver.   The light emitting device according to claim 1, wherein the protective film is made of aluminum oxide or silicon oxide.   The light emitting device according to claim 1, wherein the protective film is 1 nm or more and less than 50 nm.