CN104600179A - LED fluorescent powder layer with conformal-remote structure and preparation method - Google Patents

Abstract

The invention discloses a LED phosphor layer with a conformal-remote structure and a preparation method thereof. The steps are as follows: 1. Transparent conformal layer (pre-coating layer): transparent colloid is used to achieve conformal (conformal) coating on the surface of the LED chip. 2. Phosphor powder coating: mix the phosphor powder and colloid to form a uniform paste, and then apply the paste to the LED chip that has been pre-coated with a transparent conformal (conformal) layer to obtain a phosphor layer . The present invention can obtain a LED phosphor coating with a conformal-remote structure, because the transparent layer of the remote structure can increase the blue light extraction efficiency, so the structure can effectively increase the luminous efficiency of the LED device and reduce the thermal effect of the phosphor coating ; and the conformal transparent remote layer and phosphor coating structure can match the light intensity distribution of LEDs, which can effectively improve the light quality of white LEDs, and the spatial uniformity of light color and brightness. This technology has the advantages in pc-WLED packaging Very good application value.

Description

A LED phosphor layer with conformal-remote structure and preparation method thereof

technical field

The invention belongs to the technical field of optoelectronics, and in particular relates to an integrated preparation method of an LED fluorescent powder coating.

Background technique

LED is the abbreviation of light emitting diode (light emitting diode). According to the difference of its light emitting material, it can be divided into two categories: organic LED (ie OLED) and inorganic LED (generally called LED). In 1996, white LEDs were successfully realized on the basis of blue GaN-based light-emitting diodes, which have the advantages of low-voltage drive, all solid-state, low power consumption, long-term reliability, no pollution, and energy. Therefore, in recent years, semiconductor lighting (fourth generation lighting technology) based on white LEDs has developed rapidly.

At present, the most common way to realize white LED is phosphor conversion type (pc-LED), for example, (yellow+blue) white LED with a layer of yellow phosphor coated on the surface of blue LED chip. In addition, the realization technology of the phosphor layer mainly adopts the traditional potting process, that is, the dispensing process of phosphor powder mixed with silica gel. However, the phosphor coating obtained in this way has poor controllability due to uneven structure, so that the uniformity of light emitted by the LED is poor.

In order to overcome the above defects, it is necessary to realize the uniform controllability of the thickness and shape of the phosphor layer.

Contents of the invention

The invention obtains a LED phosphor coating structure with a conformal-remote structure by improving the LED conformal coating technology, and solves and improves some problems existing in the existing flat coating technology.

The technical solution of the present invention is: an LED phosphor layer with a conformal-remote structure and a preparation method thereof, characterized in that it comprises the following steps:

(1) Mix colloid and solvent according to a certain ratio to prepare transparent pre-coating solution;

(2), coating (1) transparent pre-coating solution on the LED chip to form a transparent conformal layer with conform properties;

(3) Mix colloid and fluorescent powder according to a certain ratio to obtain powder paste;

(4) Coating the powder slurry obtained in (3) on the LED chip with conformal transparent pre-coating in (2), forming a phosphor layer with conformal properties, and obtaining LED fluorescence with a conformal-remote structure Powder coated.

In step (1), the colloid is one or more combinations of silica gel, epoxy resin, polymethyl methacrylate (PMMA), polycarbonate (PC) or photosensitive glue; in step (3) Among them, the colloid is one or more combinations of silica gel, epoxy resin, polymethyl methacrylate (PMMA), polycarbonate (PC) or photosensitive glue; the photosensitive colloid includes the following three types of negative Photosensitive glue: ①Sensitizer + film-forming agent type, that is, photosensitive compound + polymer compound type, where the photosensitive agent is one or more of dichromate, chromate, diazo compound or azide compound a combination of species; the film-forming agent is one or more combinations of polyvinyl alcohol (PVA), gum arabic, polyimide or polyvinyl acetate emulsion; ② polymer compound type with photosensitive groups, mainly One or more of polyvinyl alcohol cinnamate, polyvinyl alcohol cinnamylidene acetate, polyvinyloxyethyl cinnamate, polyvinylpyrrolidone or polyvinyl alcohol-p-azidobenzoate (PVAB) ③SBQ photosensitive adhesive (polyvinyl acetal styryl pyridinium salt resin photosensitive adhesive), SBQ-PVA+ polymer emulsion, SBQ-PVA+ polymer emulsion + acrylate or organic styryl pyridinium salt resin photosensitive adhesive One or more combinations in the system; photosensitive colloids are one or more combinations of the above three types.

In step (1), when the colloid is made of silica gel, epoxy resin, polymethyl methacrylate (PMMA), or polycarbonate (PC), transparent silica gel, epoxy resin, polymethyl methacrylate One or more of ester (PMMA), polycarbonate (PC) and organic solvent are mixed evenly in a certain proportion, and the transparent pre-coating layer is obtained by spraying, spin coating and printing; the organic solvent is ether, ester or other alkyl organic solvents; the volume ratio of the colloid to the solvent is 0.1%-20%; the ether organic solvent is tetrahydrofuran and its modified derivatives; the ester organic solvent refers to ethyl acetate, propyl acetate, Butyl acetate or ethyl butyrate; alkyl organic solvent refers to n-heptane, n-hexane, n-pentane, n-octane.

In step (1), when the colloid is a photosensitive adhesive, an exposure and development process is used to obtain a conformal coating with conformal properties, and the exposure method is a self-exposure method using LED self-luminescence or a combination of an external light source The external exposure method of the mask plate, the external light source is an ultraviolet light source or a light source of other wavelengths that are sensitive to the photosensitive colloid, and the developing solution for development includes one of deionized water, tap water, weak acid, weak base or organic solvent or Various combinations.

In step (1), when the colloid is made of silica gel, epoxy resin, polymethyl methacrylate (PMMA), or polycarbonate (PC), spray coating, spin coating, and printing are used to obtain conformal properties. pre-coated.

In step (1), the obtained conformal transparent layer can increase the light extraction rate, and the extracted blue light is more uniform in space, so it can effectively increase the luminous efficiency of the LED device and improve the light quality and light color of the white LED. The spatial uniformity of brightness, and the conformal transparent layer isolates the chip and the phosphor layer, which can reduce the thermal effect of the phosphor layer.

In step (1), the obtained conform transparent layer can improve the adhesion between the phosphor powder and the interface, so that the subsequent phosphor powder layer can better match the light intensity distribution of the LED, and effectively improve the light quality and light color of the white LED. and spatial uniformity of brightness.

In step (2), the method of applying the pre-coating solution is one or more combinations of spraying, printing or dispensing.

In step (2), the desired drying method can be one or more combinations of natural shade drying, natural air drying, heating on a heating plate, heating in a drying oven or infrared heating.

In step (3), when the colloid is made of silica gel, epoxy resin, polymethyl methacrylate (PMMA), or polycarbonate (PC), transparent silica gel, epoxy resin, polymethyl methacrylate One or more of ester (PMMA), polycarbonate (PC) and organic solvent are mixed evenly in a certain proportion, and the transparent pre-coating layer is obtained by spraying, spin coating and printing; the organic solvent is ether, ester or other alkyl organic solvents; the volume ratio of the colloid to the solvent is 0.1%-20%; the ether organic solvent is tetrahydrofuran and its modified derivatives; the ester organic solvent refers to ethyl acetate, propyl acetate, Butyl acetate or ethyl butyrate; alkyl organic solvent refers to n-heptane, n-hexane, n-pentane, n-octane.

In step (3), when the colloid is a photosensitive adhesive, an exposure and development process is used to obtain a phosphor layer with conform properties. The external exposure method of the stencil, the external light source is an ultraviolet light source or a light source of other wavelengths sensitive to photosensitive colloid, and the developer used for development includes one or more of deionized water, tap water, weak acid, weak base or organic solvent. combination of species.

In step (3), when the colloid adopts silica gel, epoxy resin, polymethyl methacrylate (PMMA), polycarbonate (PC), spray coating, electrostatic spray coating, electrophoretic deposition, printing, spin coating A phosphor layer with conformal properties is obtained by coating.

In step (3), the structure and shape of the conformal phosphor layer have good uniformity, and the process is controllable and stable, which can effectively improve the light quality, light color and brightness of white LEDs. Uniformity.

In step (3), the fluorescent powder used is yellow fluorescent powder or three-color fluorescent powder; it can also contain one or more of green fluorescent powder or red fluorescent powder added to improve color rendering. combination.

In step (3), the particles containing phosphor may contain polymethyl methacrylate (PMMA), polystyrene (PS), titanium oxide, aluminum oxide, yttrium oxide, silicon oxide, zinc oxide, A combination of one or more of gallium nitride, silicon nitride, silicon carbide or zirconia, or only phosphor particles.

In step (4), the desired drying method may be one or more combinations of natural shade drying, natural air drying, infrared heating, oven heating or heating on a heating plate.

In step (4), the conformal-remote LED phosphor coating is to coat the phosphor layer on the remote layer with conformal properties.

In step (4), the phosphor layer may be a phosphor layer with conformal properties, or a phosphor layer with other structures.

The aforementioned LEDs are organic LEDs, inorganic LEDs or a combination of both. The LED is a single LED chip, or a group of multiple LED chips on the same substrate, or a whole wafer.

For phosphor powder pastes with different components and different concentrations, repeat steps (3) and (4) to realize multiple or multi-layer phosphor coatings on the surface of the LED device in the light emitting direction, or even phosphors with the same composition The slurry repeats the above-mentioned process steps many times, so as to obtain a multi-layer fluorescent powder coating with the same composition.

In addition, steps (2), (3) and (4) can be repeated to obtain a phosphor layer with a multi-layer structure in which conform transparent layers, phosphor layers, and conform transparent layers appear alternately.

Using this technology, one or more than one phosphor layer patterns with complete coverage and uniformity can be realized on the surface of the LED in the light emitting direction.

The technology of the present invention is not only suitable for the preparation of white LED devices of yellow light phosphor + blue LED chip, but also suitable for the white light LED implementation scheme of ultraviolet LED chip + multi-color phosphor (such as RGB tricolor phosphor), and other light-emitting colors. Phosphor conversion (pc-LEDs) devices.

The present invention can obtain a phosphor coating with a conformal-remote structure, because the conformal transparent layer can increase the blue light extraction efficiency, so the structure can effectively increase the luminous efficiency of the LED device and reduce the thermal effect of the phosphor coating; and The conformal transparent layer and powder-slurry phosphor coating structure can match the light intensity distribution of LEDs, and can effectively improve the light quality of white LEDs. This technology can be applied to both LED chip-level packaging and wafer (Wafer )-level coating packaging, which has good application value in PC-LED packaging.

Description of drawings

The accompanying drawing is a schematic diagram of obtaining a phosphor powder layer with a conformal-remote structure. Figure 1a is a schematic diagram of an LED chip; Figure 1b is a schematic diagram of an LED chip coated with a conformal pre-coat; Figure 1c is a schematic diagram of an LED coated with a phosphor powder to obtain a conformal phosphor layer with a conformal-remote structure; Figure 1d is a schematic diagram of an LED coated with a phosphor powder to obtain a conformal -Schematic diagram of LED with non-conformal phosphor layer in remote structure. Among them, 1 is the phosphor particle, 2 is the LED chip, 3 is the colloid, 4 is the pre-coating layer, and 5 is the substrate.

Detailed ways

Below in conjunction with accompanying drawing and embodiment case, the present invention will be further described:

Example 1

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 2

Weigh 0.5ml epoxy resin and 50ml ethyl acetate, mix the two evenly to obtain the precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 3

Weigh 0.1ml of silica gel and 100ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 4

Weigh 5ml of silica gel and 25ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 5

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.72ml of the prepared 5% PVA and 0.68ml of the prepared 0.26% ADC, and mix the two evenly to obtain the photosensitive adhesive;

Coat the photosensitive adhesive on the LED chip, heat and dry it in a drying oven, and then use 1A current and exposure time of 0.2ms~1ms for self-exposure; develop with deionized water and heat it to 35℃~80℃ for development, and the development time is 30s~ 5min, then rinse with deionized water or blow off the unfixed excess photosensitive adhesive to obtain a transparent conformal layer;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 6

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 1.56ml of prepared 5% PVA and 0.3ml of prepared 0.26% ADC, and mix them evenly to obtain photosensitive adhesive;

Coat the photosensitive adhesive on the LED chip, heat and dry it in a drying oven, and then use 1A current and exposure time of 0.2ms~1ms for self-exposure; develop with deionized water and heat it to 35℃~80℃ for development, and the development time is 30s~ 5min, then rinse with deionized water or blow off the unfixed excess photosensitive adhesive to obtain a transparent conformal layer;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 7

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.26ml of prepared 5% PVA and 1ml of prepared 0.26% ADC, and mix them evenly to obtain photosensitive glue;

Coat the photosensitive adhesive on the LED chip, heat and dry it in a drying oven, and then use 1A current and exposure time of 0.2ms~1ms for self-exposure; develop with deionized water and heat it to 35℃~80℃ for development, and the development time is 30s~ 5min, then rinse with deionized water or blow off the unfixed excess photosensitive adhesive to obtain a transparent conformal layer;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 8

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.15g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.3% ADC;

Weigh 0.4g of phosphor, 0.8ml of prepared 5% PVA, and 0.6ml of prepared 0.3% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 9

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.1g of dichromic acid (ADC) and 20ml of deionized water and mix well, that is, 0.5% ADC;

Weigh 0.4g phosphor, 1ml prepared 5% PVA, 0.5ml prepared 0.5% ADC, mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 10

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.1g of dichromic acid (ADC) and 100ml of deionized water and mix well, that is, 0.1% ADC;

Weigh 0.4g of phosphor, 0.4ml of prepared 5% PVA, 0.8ml of prepared 0.1% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 11

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.1g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.2% ADC;

Weigh 0.36g of phosphor, 0.8ml of prepared 5% PVA, and 0.6ml of prepared 0.2% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 12

Weigh 0.5ml of silica gel, 50ml of tetrahydrofuran, and 0.25g of polymethyl methacrylate, and mix the three evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 13

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.4g of polymethyl methacrylate, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form a slurry;

Apply the powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess Powder, forming a conformal layer containing transparent powder on the surface of the chip;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the above-mentioned LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 14

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.2g of phosphor, 0.2g of polymethyl methacrylate, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the four evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 15

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.72ml of prepared 5% PVA, 0.68ml of prepared 0.26% ADC, and 0.4g of polymethyl methacrylate, and mix the three evenly to obtain a photosensitive adhesive;

Coat the photosensitive adhesive on the LED chip, heat and dry it in a drying oven, and then use 1A current and exposure time of 0.2ms~1ms for self-exposure; develop with deionized water and heat it to 35℃~80℃ for development, and the development time is 30s~ 5min, then rinse with deionized water or blow off the excess unfixed photosensitive adhesive to obtain a transparent conformal layer containing polymethyl methacrylate particles;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 16

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Apply the pre-coating solution on the LED chip by printing to form a transparent conformal layer on the chip surface;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 17

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Apply the pre-coating solution on the LED chip by spin coating to form a transparent conformal layer on the chip surface;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 18

Weigh 0.5ml epoxy resin and 50ml tetrahydrofuran, and mix the two evenly to obtain the pre-coating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 19

Weigh 0.5ml of silica gel and 50ml of n-heptane, and mix the two evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess phosphor, obtain a conformal phosphor layer with a conformal-remote structure, and recycle the phosphor.

Example 20

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess Phosphor powder, finally heated and dried;

Then use the dispensing method to coat the phosphor powder slurry on the surface of the LED chip, and heat (40°C) in a drying oven to dry for 20 minutes;

Then use 1A current and exposure time of 0.2ms~1ms for self-exposure; develop with deionized water and heat it to 35℃~80℃ for development, the development time is 30s~5min, and then rinse with deionized water or blow off the unfixed excess The phosphor powder is heated and dried to obtain a conformal phosphor layer with a conformal-remote structure, and finally the phosphor powder is recovered.

Example 21

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.4g of phosphor, 0.72ml of prepared 5% PVA, and 0.68ml of prepared 0.26% ADC, and mix the three evenly to form phosphor paste;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Use 1A current, exposure time 0.2ms ~ 1ms self-exposure; develop with deionized water heated to 35 ℃ ~ 80 ℃ for development, the development time is 30s ~ 5min, then rinse with deionized water or blow off unfixed excess Phosphor powder, finally heated and dried;

Then heat the LED chip on the heating plate (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Then apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (40°C) in a drying oven to dry for 20 minutes;

Finally, use 1A current and exposure time of 0.2ms~1ms for self-exposure; develop with deionized water and heat it to 35℃~80℃ for development, the development time is 30s~5min, rinse with deionized water or blow off the excess The fluorescent powder is heated and dried to obtain a conformal fluorescent powder layer with a conformal-remote structure; the fluorescent powder is recycled.

Example 22

Weigh a certain amount of silica gel tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh a certain amount of phosphor, silica gel, tetrahydrofuran and mix them evenly to obtain phosphor powder slurry;

The phosphor powder slurry was coated on the surface of the pre-coated LED chip by spraying method, and dried by heating (150° C.) in a drying oven for 2 hours to obtain a conformal phosphor layer with a conformal-remote structure.

Example 23

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Put the LED chip on the heating plate to heat (120°C) and spray the pre-coating liquid to form a transparent conformal layer on the surface of the chip;

Weigh 0.2g of fluorescent powder and 2g of powder compounding glue and mix them evenly, vacuumize to remove air bubbles to obtain phosphor powder slurry;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (150° C.) in a drying oven for 2 hours to obtain a non-conformal phosphor layer with a conformal-remote structure.

Example 24

Weigh 5g of polyvinyl alcohol (PVA) and mix it with 100mL of deionized water, stir and dissolve in a boiling water bath for 30min, the solution is transparent and uniform, without nodules, stand still until the bubbles disappear, that is, 5%PVA;

Weigh 0.13g of dichromic acid (ADC) and 50ml of deionized water and mix evenly, that is, 0.26% ADC;

Weigh 0.72ml of the prepared 5% PVA and 0.68ml of the prepared 0.26% ADC, and mix the two evenly to obtain the photosensitive adhesive;

Coat the photosensitive adhesive on the LED chip, heat and dry it in a drying oven, and then use 1A current and exposure time of 0.2ms~1ms for self-exposure; develop with deionized water and heat it to 35℃~80℃ for development, and the development time is 30s~ 5min, then rinse with deionized water or blow off the unfixed excess photosensitive adhesive to obtain a transparent conformal layer;

Weigh 0.2g of fluorescent powder and 2g of powder compounding glue and mix them evenly, vacuumize to remove air bubbles to obtain phosphor powder slurry;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (150° C.) in a drying oven for 2 hours to obtain a non-conformal phosphor layer with a conformal-remote structure.

Example 25

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Apply the pre-coating solution on the LED chip by printing to form a transparent conformal layer on the chip surface;

Weigh 0.2g of fluorescent powder and 2g of powder compounding glue and mix them evenly, vacuumize to remove air bubbles to obtain phosphor powder slurry;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (150° C.) in a drying oven for 2 hours to obtain a non-conformal phosphor layer with a conformal-remote structure.

Example 26

Weigh 0.5ml of silica gel and 50ml of tetrahydrofuran, and mix the two evenly to obtain a precoating solution;

Apply the pre-coating solution on the LED chip by spin coating to form a transparent conformal layer on the chip surface;

Weigh 0.2g of fluorescent powder and 2g of powder compounding glue and mix them evenly, vacuumize to remove air bubbles to obtain phosphor powder slurry;

Apply the phosphor powder slurry on the surface of the pre-coated LED chip by dispensing method, and heat (150° C.) in a drying oven for 2 hours to obtain a non-conformal phosphor layer with a conformal-remote structure.

Claims (10)

1. there is LED fluorescent powder layer and the preparation method of conformal-remote structure, it is characterized in that, comprise the following steps:

(1), by colloid and the solvent transparent pre-coating solution of mixed preparing according to a certain percentage;

(2), transparent to (1) pre-coating solution is coated in transparent conformal layer LED chip being formed there is conformal attribute;

(3), colloid and the particle containing fluorescent material are mixed acquisition powder slurry according to a certain percentage;

(4), the powder obtained in (3) slurry is coated on the LED chip of the existing transparent precoated shet of conformal in (2), forms phosphor powder layer, obtain the LED fluorescent powder coating with conformal-remote structure.

2. a kind of LED fluorescent powder layer and preparation method with conformal-remote structure according to claim 1, it is characterized in that: in step (1), described colloid is one or more combinations in silica gel, epoxy resin, polymethyl methacrylate (PMMA), Merlon (PC) or photosensitive colloid; In step (3), described colloid is one or more combinations in silica gel, epoxy resin, polymethyl methacrylate (PMMA), Merlon (PC) or photosensitive colloid.

3. a kind of LED fluorescent powder layer and preparation method with conformal-remote structure according to claim 1, it is characterized in that: in step (4), the powder obtained in step (3) slurry is coated on the LED chip of the existing transparent precoated shet of conformal in step (2), form the phosphor powder layer with conformal attribute, obtain the LED fluorescent powder coating of the conformal with conformal-remote structure.

4. a kind of LED fluorescent powder layer and preparation method with conformal-remote structure according to claim 2, it is characterized in that: described photosensitive colloid comprises following three class negative-working photoresists: 1. emulsion+film forming formulation, i.e. photosensitive compounds+macromolecular compound type, wherein emulsion is one or more the combination in bichromate, chromate, diazonium compound or azido cpd; Film forming agent is one or more the combination in polyvinyl alcohol (PVA), gum arabic, polyimides or polyvinyl acetate emulsion; 2. the macromolecular compound type with photosensitive base, mainly contains one or more the combination in polyvinyl cinnamate, polyvinyl alcohol Chinese cassia tree fork acetic acid esters, polyethylene oxygen ethyl-cinnamic acid ester, polyvinylpyrrolidone or polyvinyl alcohol-p-azidobenzoic acid ester (PVAB); 3. one or more the combination in SBQ photoresists (polyvinyl alcohol cyclic ketal styryl pyridinium resin photoresists), SBQ-PVA+ macromolecule emulsion, SBQ-PVA+ macromolecule emulsion+acrylate or organic benzene, organic vinylpyridine salt resin photoresists system; Photosensitive colloid is the combination of a class in above-mentioned three classes or multiclass; Then the conformal coating of exposure, developing process acquisition conformal attribute is adopted.

5. a kind of LED fluorescent powder layer and preparation method with conformal-remote structure according to claim 4, it is characterized in that: described Exposure mode be adopt LED self luminescence from Exposure mode or adopt outer light source in conjunction with the outer Exposure mode of mask plate, described outer light source is the light source of other wavelength of ultraviolet source or photosensitive colloid sensitivity; The developer solution of development comprises one or more the combination in deionized water, running water, weak acid, weak base or organic solvent.

6. a kind of LED fluorescent powder layer and preparation method with conformal-remote structure according to claim 1, it is characterized in that: in step (2), described pre-coating solution painting method is spraying, electrostatic spraying, electrophoretic deposition, printing, spin coating, perfusion, dipping or one or more the combination of some glue, adopt spraying, printing, spin coating coating method can directly obtain conformal layer, also first spraying can be adopted, electrostatic spraying, electrophoretic deposition, printing, spin coating, perfusion, then dipping or some glue coating method need to adopt exposure, developing process obtains the conformal coating of conformal attribute, in step (3), described powder slurry painting method is one or more the combination in spraying, electrostatic spraying, electrophoretic deposition, printing, spin coating, perfusion, dipping or some glue.

7. a kind of LED fluorescent powder layer and preparation method with conformal-remote structure according to claim 1, it is characterized in that: in step (1), described colloid is transparent silica gel, epoxy resin, polymethyl methacrylate (PMMA), during one or more combinations of Merlon (PC), first will by transparent silica gel, epoxy resin, polymethyl methacrylate (PMMA), Merlon (PC) one or more and organic solvent in certain ratio mix, then spraying is adopted, spin coating, the modes such as printing obtain the conformal precoated shet with conformal attribute.

8. a kind of LED fluorescent powder layer and preparation method with conformal-remote structure according to claim 7, is characterized in that: described organic solvent is the organic solvent of ethers, ester class or other alkyl; Described colloid and solvent volume ratio are 0.1%-20%; Ether organic solvent is oxolane and the derivative after modifying thereof; Based organic solvent refers to ethyl acetate, propyl acetate, butyl acetate or ethyl butyrate, pentyl acetate; Alkyl organic solvent refers to normal heptane, normal hexane, pentane, normal octane.

9. a kind of LED fluorescent powder layer and preparation method with conformal-remote structure according to claim 1, is characterized in that: in step (3), and fluorescent material used is yellow fluorescent material or the fluorescent material of three primary colors; Can also be included as simultaneously and improve color rendering and one or more combination in the green emitting phosphor that adds or red fluorescence powder.

10. a kind of LED fluorescent powder layer and preparation method with conformal-remote structure according to claim 1, it is characterized in that: in step (3), described comprises in the particle of fluorescent material one or more the combination that can contain in polymethyl methacrylate (PMMA), polystyrene (PS), titanium oxide, aluminium oxide, yittrium oxide, silica, zinc oxide, gallium nitride, silicon nitride, carborundum or zirconia, also can only have fluorescent powder grain.