CN102867891B - method for coating fluorescent powder and light emitting diode package - Google Patents

Abstract

The invention provides a method for coating phosphor and a light-emitting diode package. The method includes providing a light-emitting diode with a conductive pad and a protective layer on it. The protective layer is arranged in an area other than the conductive pad to modify the core phosphor. A modified phosphor is formed, which has functional groups modified on the core phosphor. The modified phosphor is coated on the light-emitting diode, and the functional groups of the modified phosphor are adsorbed on the protective layer without It will be adsorbed on the conductive pad to form a light-emitting diode package.

Description

Method for Coating Phosphor Powder and Encapsulation of Light Emitting Diode

technical field

The invention relates to a light-emitting diode, in particular to a method for coating fluorescent powder on the light-emitting diode.

Background technique

A light-emitting diode (light-emitting diode, referred to as LED) is a composite semiconductor component that converts current into light through energy conversion. A single light-emitting diode can only emit light of a specific light color, so it is usually necessary Phosphor powder is coated on it, so as to convert the light color emitted by the light emitting diode into the required light color, for example, yellow phosphor powder is coated on the blue light emitting diode to form a white light emitting diode.

The traditional method of coating phosphor on LEDs is to use a syringe or nozzle to coat the phosphor colloid on the LEDs. However, this coating method is difficult to accurately control the area where the phosphor is coated and the area where the phosphor is coated. Thickness, causing areas on the LED that are not expected to be coated with phosphor to be covered with phosphor.

Another way is to use photolithography process to cover the area of the light-emitting diode that is not expected to be covered by the phosphor with a photoresist layer, and then remove the photoresist layer after the phosphor powder is coated. However, this method needs to add a photolithography step to form the photoresist layer, so the manufacturing process is more complicated.

Contents of the invention

An embodiment of the present invention provides a method for coating phosphor, comprising: providing a light-emitting diode with a conductive pad and a protective layer covering the light-emitting diode, wherein the protective layer is disposed on an area other than the conductive pad; providing a core phosphor, Modifying the core phosphor to form a modified phosphor, the modified phosphor has a functional group modified on the core phosphor; and coating the modified phosphor on the light-emitting diode, wherein the modified phosphor The functional groups of the powder are adsorbed on the protective layer, but not on the conductive pad.

Another embodiment of the present invention provides a method for coating phosphor, comprising: providing a light-emitting diode with a conductive pad formed thereon; providing a surface modifier on the light-emitting diode, wherein the surface modifier is adsorbed on the conductive pad , without being adsorbed on the area other than the conductive pad; coating the core phosphor on the light-emitting diode; and applying a potential to the conductive pad, so that the surface modifier is desorbed from the conductive pad.

An embodiment of the present invention also provides a light-emitting diode package, including: a light-emitting diode with a conductive pad and a protective layer covering the light-emitting diode, wherein the protective layer is disposed on an area other than the conductive pad; and the modified phosphor is covered on The protective layer is not covered on the conductive pad, wherein the modified phosphor has functional groups modified on the core phosphor.

In order to make the above-mentioned purpose, features, and advantages of the present invention more comprehensible, a detailed description is given below in conjunction with the accompanying drawings.

Description of drawings

1A to 1C are schematic cross-sectional views showing various process stages of a phosphor coating method according to an embodiment of the present invention.

FIG. 1D shows an enlarged schematic view at the box line 1D in FIG. 1B .

2A to 2E are schematic cross-sectional views showing various process stages of a phosphor coating method according to another embodiment of the present invention.

Reference signs:

10: base;

12: LED;

14: conductive pad;

16: protective layer;

17: core phosphor;

18: modified phosphor;

19: a modified functional group;

20: surface modifier.

Detailed ways

Embodiments of the present invention utilize molecular self-assembly (self-assembly) to regulate phosphor-coated areas on light-emitting diodes, which does not require forming a photoresist layer on light-emitting diodes to cover areas that do not want to be coated with phosphors , such as the conductive pad (conductivepad) area on the light-emitting diode, that is, the phosphor can skip the area that is not expected to be coated with the phosphor when coating, so compared with the traditional coating of phosphor on the light-emitting diode The method, the method of the embodiment of the present invention can save a lithography process step, and effectively simplify the phosphor coating process procedure.

Referring to FIGS. 1A to 1C , which show schematic cross-sectional views of each process stage of a phosphor coating method according to an embodiment of the present invention. Referring to FIG. 1A , light emitting diodes 12 are firstly provided, such as a plurality of light emitting diodes 12 formed on a substrate 10, which may be a sapphire substrate, a silicon wafer or other semiconductor wafers, and the light emitting diodes 12 are, for example, blue light diodes. There is a conductive pad 14 on the surface of the light emitting diode 12. In one embodiment, the conductive pad 14 can be used as an n-type contact (contact). In addition, there is another conductive pad (not shown) on the light emitting diode 12, which can be used as an n-type contact. p-type contacts. The material of the conductive pad 14 includes metal, such as gold (Au). In addition, there is a protective layer 16 on the light emitting diode 12. The protective layer 16 covers the area other than the conductive pad 14. The material of the protective layer 16 is, for example, silicon dioxide (SiO ₂ ), which can usually be obtained by thermal oxidation or deposition. Formed in an integrated manner, thereby protecting the light emitting diode 12.

Next, referring to FIGS. 1B and 1D , FIG. 1B shows a schematic cross-sectional view of coating the modified phosphor 18 on the light-emitting diode 12 , and FIG. 1D shows an enlarged schematic view at the frame line 1D in FIG. 1B . First, modify the core phosphor 17, such as yellow phosphor (Y ₃ Al ₅ O ₁₂ :Ce; yttrium aluminum garnet, referred to as YAG) or red, green and blue (RGB) phosphor, and replace the functional group 19 Modified on the core phosphor 17 to form a modified phosphor 18 . Next, the modified phosphor powder 18 is coated on the LED 12 chip by spray coating, dispensing or spin coating.

The functional group 19 modified on the core phosphor 17 is, for example, -SiCl ₃ , -Si(OCH ₃ ) ₃ , -Si(OCH ₂ CH ₃ ) ₃ , -CH ₃ , -COOH or -NH ₂ , and the functional group 19 can be Produce self-assembly interaction with the protective layer 16 on the light-emitting diode 12, the self-assembly interaction includes hydrogen bond, π-π stacking interaction (π-πstacking interaction), coordination covalent bond (coordinate covalent bond) or donor/acceptor or interaction (adaptor/receptor interaction), the self-assembly force allows the functional group 19 to be adsorbed on the protective layer 16, but the functional group 19 will not generate self-assembly force with the conductive pad 14, so the functional group 19 will not be adsorbed on the protective layer 16. Conductive pad 14. By modifying the functional group 19 on the core phosphor powder 17 , the modified phosphor powder 18 can be arranged on the protective layer 16 without being deposited on the conductive pad 14 .

In one embodiment, the modified functional group 19 on the core phosphor 17 is a trichlorosilane group (-SiCl ₃ ), when -SiCl ₃ is adsorbed on the hydrophilic SiO ₂ protective layer 16, first -SiCl ₃ will The hydrolysis reaction with the moisture on the surface of the SiO ₂ protective layer 16 forms -Si(OH) ₃ , and the -Si(OH) ₃ is adsorbed on the SiO ₂ protective layer 16, and these -OH bonds will interact with the surrounding area by hydrogen bonding. The —OH bond in the phosphor is bonded, and then the water molecule is removed to generate a polymerization reaction, forming a network structure bonded between the core phosphor 17 and the protective layer 16 . Therefore, the modified fluorescent powder 18 formed on the core fluorescent powder 17 by using _-SiCl3 functional group 19 can not only arrange itself on the protective layer 16, but also form a stable single-layer film with a network structure, so that the modified The phosphor powder 18 is stably coated on the SiO ₂ protective layer 16 and avoids the area of the conductive pad 14 .

Referring to FIGS. 1B to 1C , the light emitting diodes 12 are cut and separated along the cutting line SC in FIG. 1B to form a light emitting diode package as shown in FIG. , wherein the protective layer 16 is disposed on the area other than the conductive pad 14 , and the modified phosphor powder 18 covers the protective layer 16 and the substrate 10 , but does not cover the conductive pad 14 .

Referring to FIGS. 2A to 2E , which show schematic cross-sectional views of each process stage of a phosphor coating method according to another embodiment of the present invention. Referring to FIG. 2A , light emitting diodes 12 are firstly provided, such as a plurality of light emitting diodes 12 formed on a substrate 10, which may be a sapphire substrate, a silicon wafer or other semiconductor wafers, and the light emitting diodes 12 are, for example, blue light diodes. There is a conductive pad 14 on the surface of the light-emitting diode 12. In one embodiment, the conductive pad 14 can be used as an n-type contact (contact). In addition, there is another conductive pad (not shown) at the bottom of the light-emitting diode 12. It can be used as a p-type contact, and the material of the conductive pad 14 includes metal, such as gold (Au).

Referring to FIG. 2B , a surface modifier 20 is provided to be coated on the light-emitting diode 12. The surface modifier 20 is, for example, a thiol compound, which can be adsorbed on the conductive pad 14 made of gold by self-assembly, without It will be adsorbed on the area other than the conductive pad 14. When the thiol compound is adsorbed on the surface of the conductive pad 14 made of gold, the gold of the conductive pad 14 becomes monovalent gold (Au(I)).

Referring to FIG. 2C, the core phosphor 17 is coated on the light emitting diode 12 by spray coating, dispensing or spin coating. The core phosphor 17 is, for example, yellow phosphor (Y ₃ Al ₅ O ₁₂ :Ce; yttrium aluminum garnet, referred to as YAG) or red, green and blue (RGB) phosphor. Since the conductive pad 14 is covered by the surface modifying agent 20 , the core phosphor 17 is only coated on the area other than the conductive pad 14 , covering the surface of the LED 12 chip and the substrate 10 .

Referring to FIG. 2D, apply a potential of about 0.05V to the conductive pad 14, so that the conductive pad 14 with a valence of gold (Au(I)) is reduced to 0-valent gold (Au(0)), at this time the surface modifier 20 will detach from the conductive pad 14.

Next, referring to FIGS. 2D to 2E, the light emitting diodes 12 are cut and separated along the cutting line SC in FIG. 2D to form a light emitting diode package as shown in FIG. The fluorescent powder 17 covers the LED 12 and the substrate 10 , but does not cover the conductive pad 14 .

To sum up, the embodiment of the present invention allows the modified phosphor to be adsorbed on the protective layer instead of the conductive pad of the LED chip through the self-assembly between molecules; or the surface modifier Adsorbed on the conductive pad, but not on the area other than the conductive pad, so that the phosphor will not be coated on the conductive pad, so as to save the lithography process of forming a photoresist layer covering the conductive pad, and reduce the process steps of LED packaging .

Although the present invention has disclosed the preferred embodiment as above, it is not intended to limit the present invention, and any person of ordinary skill in the art may make some changes and modifications without departing from the spirit and scope of the present invention.

Claims (12)

1. be coated with a method for fluorescent material, comprise:

There is provided a light-emitting diode, have a conductive pad and a protective layer is covered on this light-emitting diode, wherein this protective layer is arranged at the region beyond this conductive pad, and the material of this protective layer comprises silicon dioxide;

There is provided a core fluorescent powder, carry out upgrading, form the fluorescent material of a upgrading to this core fluorescent powder, the fluorescent material of this upgrading has a functional group and modifies on this core fluorescent powder, and this functional group comprises-SiCl ₃,-Si (OCH ₃) ₃,-Si (OCH ₂cH ₃) ₃,-CH ₃,-COOH or-NH ₂; And

By the fluorescent powder coating of this upgrading on this light-emitting diode, this functional group that wherein fluorescent material of this upgrading has is adsorbed on this protective layer, and can not be adsorbed on this conductive pad.

2. the method for coating fluorescent material according to claim 1, this functional group that wherein fluorescent material of this upgrading has is-SiCl ₃, should-SiCl ₃the aqueous vapor of functional group and this protective layer produces hydrolysis, forms-Si (OH) ₃functional group is also adsorbed on this protective layer, and should-Si (OH) ₃functional group also produces dehydration polymerization reaction further, forms a network structure and is binding between this core fluorescent powder and this protective layer.

3. the method for coating fluorescent material according to claim 1, wherein this core fluorescent powder comprises yellow fluorescent powder or redgreenblue fluorescent material.

4. the method for coating fluorescent material according to claim 3, wherein this yellow fluorescent powder comprises yttrium-aluminium-garnet (Y ₃al ₅o ₁₂: Ce, be called for short YAG).

5. the method for coating fluorescent material according to claim 1, wherein the material of this conductive pad comprises metal.

6. the method for coating fluorescent material according to claim 5, wherein this metal comprises gold.

7. a LED package, comprising:

One light-emitting diode, has a conductive pad and a protective layer is arranged on this light-emitting diode, and wherein this protective layer is covered in the region beyond this conductive pad, and this protective layer comprises silicon dioxide layer; And

The fluorescent material of one upgrading, is covered on this protective layer, and is not covered on this conductive pad, and wherein the fluorescent material of this upgrading has a functional group and modifies on a core fluorescent powder, and this functional group comprises-SiCl ₃,-Si (OCH ₃) ₃,-Si (OCH ₂cH ₃) ₃,-CH ₃,-COOH or-NH ₂.

8. LED package according to claim 7, this functional group that wherein fluorescent material of this upgrading has is-SiCl ₃, should-SiCl ₃functional group is adsorbed on this protective layer, and also produces a network structure and be binding between this core fluorescent powder and this protective layer.

9. LED package according to claim 7, wherein this core fluorescent powder comprises yellow fluorescent powder or redgreenblue fluorescent material.

10. LED package according to claim 9, wherein this yellow fluorescent powder comprises yttrium-aluminium-garnet (Y ₃al ₅o ₁₂: Ce, be called for short YAG).

11. LED package according to claim 7, wherein the material of this conductive pad comprises metal.

12. LED package according to claim 11, wherein this metal comprises gold.