WO2011132805A1

WO2011132805A1 - Method for coating an led

Info

Publication number: WO2011132805A1
Application number: PCT/KR2010/002548
Authority: WO
Inventors: 방동수
Original assignee: 우리엘에스티 주식회사
Priority date: 2010-04-23
Filing date: 2010-04-23
Publication date: 2011-10-27

Abstract

The present disclosure relates to a method for coating an LED comprising a multilayered semiconductor layer and a bonding pad included therein, wherein the coating method comprises steps of: preparing a coating material on the LED; forming a hardened coating layer in the LED by selectively irradiating a coating material with light which cannot pass through the bonding pad, in the direction from the multilayered semiconductor layer toward the bonding pad; and removing unhardened coating material.

Description

Coating method of light emitting diode

The present disclosure relates to a method of coating a light emitting diode as a whole, and more particularly, to a method of coating a light emitting diode that can be applied to a process of molding a surface of a light emitting diode.

This section provides background information related to the present disclosure which is not necessarily prior art.

1 is a view for explaining an example of a conventional method of coating a light emitting diode, the light emitting diode 110 is coated in a fixed state bonded to the mount 120.

The mount 120 includes a lead frame 130 into which power is introduced, and the light emitting diode 110 is electrically connected to the lead frame 130. In general, the thin metal wire 140 is connected, which is referred to as a 'wire bonding process'.

The coating is performed by dropping the coating material 150 in the form of droplets onto the light emitting diodes 110 in which the wire bonding process is completed.

The coating material 150 in the form of droplets is cured in a state in which it flows and surrounds the light emitting diodes 110.

As a result, the coating of the light emitting diodes 110 is completed.

In this case, since the light emitting diodes 110 are fixed to the mount 120 and the coating is performed after the wire bonding process is completed, if a defect occurs in the coating process, the light emitting diode 110 is disposed together with the mount 120, thereby causing a large loss. .

In addition, since the coating material in the state of droplets must be supplied to each mount 120, a lot of man-hours enter into the coating process, resulting in a drop in yield.

In addition, since the thickness of the light emitting diode 110 is coated is determined by the flow of the coating material in the droplet state, there is a problem that it is almost impossible to form a constant coating thickness.

This is described later in the section titled 'Details of the Invention.'

This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all, provided that this is a summary of the disclosure. of its features).

According to one aspect of the present disclosure, there is provided a method of coating a light emitting diode including a multilayer semiconductor layer and a bonding pad provided therein, the method comprising: providing a coating material on the light emitting diode; Selectively irradiating light that does not pass through the bonding pad to the coating material in a direction from the multilayer semiconductor layer to the bonding pad to form a cured coating layer on the light emitting diode; And removing the uncured coating material. A coating method of a light emitting diode is provided.

This is described later in the section titled 'Details of the Invention.'

1 is a view for explaining an example of a coating method of a conventional light emitting diode,

2 to 5 are views for explaining step by step an example of a coating method of a light emitting diode according to the present disclosure;

6 is a view for explaining another example of the coating method of the light emitting diode according to the present disclosure.

The present disclosure will now be described in detail with reference to the accompanying drawing (s).

2 to 5 are diagrams for explaining an example of a method of coating a light emitting diode according to the present disclosure step by step, the step of placing a plurality of light emitting diodes 10 at a predetermined interval (see Fig. 2), Providing a coating material 20 on the light emitting diodes 10 (see FIG. 3), selectively curing the coating material 20 (see FIG. 4) and

uncured coating materials

20c, 20d. Removing (see FIG. 5).

Referring to FIG. 2, the light emitting diode 10 includes an n-type semiconductor layer 11c that provides electrons, a p-type semiconductor layer 11a that provides holes, an n-type semiconductor layer 11c, and a p-type semiconductor layer. Interposed between (11a) and provided in a multi-layer structure including an active layer (11b) is generated by the recombination of the provided electrons and holes.

Examples of the material constituting the multilayer semiconductor layer 11 include a group III nitride semiconductor, a group 2 oxide semiconductor, and a GaAs-based semiconductor used for red light emission.

The semiconductor layer 11 of the multi-layer structure is grown on the substrate 13 mainly by MOCVD (organic metal vapor growth method).

The substrate 13 may be a GaN-based substrate used as a homogeneous substrate when a group III nitride semiconductor is grown, and a sapphire substrate, a SiC substrate, or a Si substrate may be used as a heterogeneous substrate.

On the other hand,

bonding pads

15a and 15c are provided on the n-type semiconductor layer 11c and the p-type semiconductor layer 11a, respectively.

The

bonding pads

15a and 15c may be formed of an electrically conductive material and may be formed of a material containing chromium (Cr), and may include a material including titanium (Ti) instead of chromium (Cr). It may be provided. In addition, gold (Au), aluminum (Al) may be provided as a material further containing.

As a result, light is prevented from being transmitted through the

bonding pads

15a and 15c, and a function as a photo mask of the

bonding pads

15a and 15c described later can be improved.

Specifically, chromium (Cr) is most commonly used as the metal material of the photomask, because of good adhesion to quartz or glass, high pattern accuracy, and strong chemical resistance during cleaning. This is because the overall life is long.

Here, the substrate 13 on which the semiconductor layer 11 of the multilayer structure is grown is referred to as a so-called epi-wafer, and the light emitting diode 10 is formed by a process of cutting an epi wafer.

The process of cutting the epi wafer is performed using a laser or diamond cutting machine.

The plurality of light emitting diodes 10 separated by the process of cutting the epi wafer is attached to the fixing member 30 to prevent movement of the light emitting diodes.

The fixing member 30 is made of a light-transmissive substrate coated with an adhesive or a stretchable material (eg, transparent tape).

The interval between the plurality of light emitting diodes 10 attached to the fixing member 30 may be widened by stretching the fixing member 30.

Alternatively, a process of arranging the separated plurality of light emitting diodes 10 according to the performance through a performance test may be added, and in this process, the light emitting diodes 10 may be arranged to form a gap between the light emitting diodes 10.

Next, referring to FIG. 3, the coating material 20 is applied to the light emitting diodes 10 disposed on the fixing member 30 by a predetermined interval.

The coating material 20 is applied to a thickness covering the light emitting diodes 10.

At this time, it is necessary to properly adjust the application rate of the coating material 20 so that the applied coating material 20 has a predetermined thickness.

On the other hand, when the speed of applying the coating material 20 is fast, since bubbles may occur in the interval between the applied coating material 20 or the plurality of light emitting diodes 10, the application speed of the coating material 20 to prevent this It is necessary to adjust properly.

The coating material 20 is provided with a photocurable material that is cured by light.

Examples of the photocurable material include UV epoxy and UV-patternable polymer, and may be provided with a resin that may be cured or patterned by light.

In particular, the coating material 20 is preferably provided with a photocurable material that is cured by light in the ultraviolet region.

Generally, the curable material (resin) is divided into a photocurable resin and a thermosetting resin. Thermosetting resins are resins cured by heat (or infrared rays) and have stable characteristics and reliability. On the other hand, the curing time is longer than that of the photocurable resin, and there is a disadvantage that it cannot be used when patterning is required or to be locally cured.

On the other hand, the photocurable resin is generally a resin cured by ultraviolet rays, so that curing is performed in a short time, so that the process time may be shortened and local curing may be required or patterning may be used.

On the other hand, the coating material 20 may be mixed with a phosphor 23 for changing the wavelength of the light emitted from the active layer (11b).

As a result, various colors of light emitted from the light emitting diodes 10 may be produced.

Next, referring to FIG. 4, a photo mask 40 is provided under the fixing member 30 for the selective curing of the applied coating material 20.

The photo mask 40 may have a window A partitioned into a number corresponding to the plurality of light emitting diodes 10, that is, light aligned with an interval between the light transmitting region and the plurality of light emitting diodes 10. It does not have the mask pattern of the area B.

The plurality of windows A are provided to be aligned with the plurality of light emitting diodes 10, and the light emitting diodes 10 are positioned inside the outline of each window A.

As a result, a predetermined horizontal gap W is formed between the outline of each window A and the side surface of the light emitting diode 10 corresponding thereto.

Next, light for curing the coating material 20 is irradiated from the lower portion of the photo mask 40 toward the upper portion of the light emitting diode 10.

Light is preferably provided with light in the ultraviolet region.

As a result, the coating material 20a on each side of the light emitting diode 10 is cured by a part of the light passing through the window A, and the coating material 20b on the top surface of the light emitting diode 10 is formed by the window A. FIG. And light transmitted through the light emitting diode 10. However, the coating material 20c at intervals between the respective light emitting diodes 10 is kept uncured by the region B through which light cannot pass.

Meanwhile, the coating material 20d on the

bonding pads

15a and 15c among the coating materials on the upper surface of the light emitting diode 10 is kept uncured because light is blocked by the

bonding pads

15a and 15c.

Here, the

bonding pads

15a and 15c function as a kind of photo mask.

Therefore, the difficulty of forming the mask pattern corresponding to the

bonding pads

15a and 15c having a very small size can be eliminated, and the labor cost is reduced because the mask pattern corresponding to the

bonding pads

15a and 15c is not required. The yield of the coating process can be greatly improved.

On the other hand, in this example, the thickness of the coating material 20a is coated on the side of the light emitting diode 10 according to the horizontal distance (W) between the outline of each window (A) and the side of the light emitting diode 10 corresponding thereto. Is determined.

Therefore, the thickness of the coating material 20a on the side surface of the light emitting diode 10 may be optimized by adjusting the horizontal spacing W between the outline of the window A and the side surface of the light emitting diode 10.

In addition, in this example, the light is preferably irradiated in a direction perpendicular to the

bonding pads

15a and 15c from the bottom of the multilayer semiconductor layer 11 so that the side coating thickness of the light emitting diode 10 is constant.

Meanwhile, in the present example, the case in which the photo mask 40 is separately provided has been described, but it will be possible to form the mask pattern directly on the lower surface of the fixing member 30.

In this case, the process becomes simpler.

Next, referring to FIG. 5, the

uncured coating materials

20c and 20d are removed.

In this process, since the plurality of light emitting diodes 10 are coated in a separated state from each other, a mechanical process for separation of each light emitting diode 10 is unnecessary.

In addition, since the coating material 20d on the

bonding pads

15a and 15c is also removed without curing, the wire bonding process may be performed after the coating process is completed.

6 is a view for explaining another example of the coating method of the light emitting diode according to the present disclosure, in order to control the thickness of the coating material 20 applied to the light emitting diode 10, the coating material 20 is fixed member ( There is a difference from the above-described example in that the flow preventing film 35 which is prevented from continuously flowing in the direction parallel to the 30 is provided around the fixing member 30.

The flow preventing film 35 is formed to be higher than the thickness of the light emitting diode 10, in which case the thickness of the coating material 20 may be controlled by the amount of the coating material 20 supplied for the application of the light emitting diode 10. Could be.

Hereinafter, various embodiments of the present disclosure will be described.

(1) The coating method of the light emitting diode, characterized in that the coating material provided on the bonding pad is not cured. This is made possible by irradiating light curing the coating material on the bottom surface of the light emitting diode. In this case, the bonding pad serves as a kind of mask.

(2) A method of coating a light emitting diode, wherein light is irradiated from a lower portion of the multilayer semiconductor layer in a direction perpendicular to the bonding pad. This is removed in the vertical direction of the bonding pad when the uncured coating material is removed, thereby making the wire bonding process easier.

(3) The method of coating a light emitting diode, characterized in that the bonding pad is made of an electrically conductive material that does not transmit ultraviolet light. As a result, the bonding pad functions as a mask and reduces the number of labors required to manufacture a separate mask corresponding to the bonding pad for wire bonding.

(4) The coating method of the light emitting diode, characterized in that the coating material comprises a phosphor.

(5) The step of forming a cured coating layer is a method of coating a light emitting diode, characterized in that for selectively irradiating light to the coating material using a photo mask provided under the multi-layer semiconductor layer.

(6) The photomask has at least one window partitioned so as to correspond to one light emitting diode and has light transmitted therethrough, and the thickness of the cured coating layer formed on the side of the light emitting diode is equal to the horizontal gap of the window and the multilayer semiconductor layer. Method of coating a light emitting diode, characterized in that controlled by.

(7) A coating method of a light emitting diode, characterized in that provided with a plurality of light emitting diodes, arranged apart by a predetermined interval.

(8) The plurality of light emitting diodes are fixed integrally by the light transmitting member, and the step of forming the cured coating layer is a photo mask provided under the light transmitting member, which is partitioned so as to correspond to the plurality of light emitting diodes one-to-one and transmits light. A method of coating a light emitting diode, comprising irradiating light selectively to a coating material using a photomask having two windows.

(9) A method of coating a light emitting diode, wherein the photo mask is provided on the lower surface of the light transmitting member.

(10) The method of coating a light emitting diode, characterized in that the outline of one light emitting diode is located inside the outline of the window corresponding one to one.

(11) The coating material includes a phosphor, and the bonding pad is coated with a light emitting diode, characterized in that provided with an electrically conductive material containing chromium (Cr).

(12) The plurality of light emitting diodes are fixed integrally by the light transmissive member, and the step of forming the cured coating layer is a pattern formed on the lower surface of the light transmissive member. Method of coating a light emitting diode, characterized in that for selectively irradiating light to the coating material using a pattern comprising a.

According to one method of coating a light emitting diode according to the present disclosure, since the bonding pad provided in the light emitting diode is used as a kind of photo mask, the cost and labor required to manufacture a separate photo mask for removing the coating material on the upper portion of the bonding pad is reduced. Removal can greatly improve yield.

In addition, according to another method of coating a light emitting diode according to the present disclosure, since the light emitting diode is fixed to the mount or coated before the wire bonding process, a loss due to coating failure may be reduced.

In addition, according to another method of coating a light emitting diode according to the present disclosure, since coating is performed by photocuring in a state in which a coating material is applied to a plurality of light emitting diodes at the same time, the labor required for the coating process can be reduced. Therefore, manufacturing yield can be improved.

Claims

In the method of coating a light emitting diode comprising a multilayer semiconductor layer and a bonding pad provided therein,

Providing a coating material on the light emitting diode;

Selectively irradiating light that does not pass through the bonding pad to the coating material in a direction from the multilayer semiconductor layer to the bonding pad to form a cured coating layer on the light emitting diode; And

Removing the uncured coating material; coating method of a light emitting diode comprising a.
The method according to claim 1,

Coating method of the light emitting diode, characterized in that the coating material provided on the bonding pad is not cured.
The method according to claim 1,

The light is irradiated in a direction perpendicular to the bonding pad from the lower portion of the multilayer semiconductor layer coating method of the light emitting diode.
The method according to claim 1,

The coating material is provided with a photocurable resin, the light is UV coating method, characterized in that the ultraviolet light.
The method according to claim 4,

Bonding pad is a coating method of a light emitting diode, characterized in that provided with an electrically conductive material that does not transmit ultraviolet light.
The method according to claim 1,

The coating material is a coating method of the light emitting diode, characterized in that it comprises a phosphor.
The method according to claim 1,

Forming the cured coating layer is a method of coating a light emitting diode, characterized in that for selectively irradiating light to the coating material using a photo mask provided under the multilayer semiconductor layer.
The method according to claim 1,

The photo mask is partitioned to correspond to one light emitting diode and has at least one window through which light is transmitted.

The thickness of the cured coating layer formed on the side of the light emitting diode is a coating method of the light emitting diode, characterized in that controlled by the horizontal gap of the window and the multilayer semiconductor layer.
The method according to claim 1,

The light emitting diode is provided with a plurality, the coating method of the light emitting diode, characterized in that arranged at a predetermined interval apart.
The method according to claim 9,

The plurality of light emitting diodes are integrally fixed by the light transmitting member,

The cured coating layer forming step is a photo mask provided on the lower part of the light transmissive member, and selectively irradiates light onto the coating material by using a photo mask having a plurality of windows through which light is transmitted and partitioned to correspond to the plurality of light emitting diodes one-to-one. Coating method of the light emitting diode, characterized in that.
The method according to claim 10,

The photo mask is provided on the lower surface of the light transmitting member, the coating method of the light emitting diode.
The method according to claim 10,

The outline of one light emitting diode is located inside the outline of the window corresponding one-to-one with the light emitting diode coating method.
The method according to claim 10,

The coating material includes a phosphor,

Bonding pad is a coating method of a light emitting diode, characterized in that provided with an electrically conductive material containing chromium (Cr).
The method according to claim 9,

The plurality of light emitting diodes are fixed integrally by the light transmitting member,

The step of forming the cured coating layer is a pattern formed on the lower surface of the light transmissive member, and selectively irradiating light to the coating material using a pattern including a region A through which light passes and a region B through which light cannot pass. A method of coating a light emitting diode, characterized in that.