CN104953005A - High-power LED packaging - Google Patents

Abstract

The invention provides high-power LED packaging, which comprises an LED light emitting chip and an LED support. The surface of the chip is coated with fluorescent glue; a lens is arranged above the support; the thickness of the position on the surface of the chip coated with the fluorescent glue is larger than that of the position at the side edge of the chip, an arc shape is formed after coating of the fluorescent glue, the radian is consistent with that of the lens, small particle phosphor is added to large particle phosphor according to the fluorescent glue, the phosphor after mixing is combined and mixed with silica gel for a period of time, vacuum processing is then carried out, an angle alpha formed between the wall of a support bowl and the bottom is 40 to 50 DEG, and the bowl has a height h of 0.3mm to 0.45mm. The LED can emit light more uniformly, and spot can be effectively improved.

Description

A high-power LED package

Technical field: The present invention relates to the field of LED technology, in particular to a high-power LED package.

Background technology: LED light-emitting diode is a light-emitting device that can directly convert electrical energy into visible light and radiation energy. The structure of the light-emitting diode includes two parts: the carrying part has two conductive ends with different polarities, and the carrying part is equipped The chip and the fluorescent material are connected to the electrode layer and the conductive end of the chip with gold wires, and finally the packaging process is completed. Compared with traditional lighting technology, this new type of light source has leading advantages such as high efficiency, energy saving, long life, small size, and low cost. At present, the commonly used LED mainly uses the combination of the light of the chip and the wavelength of the fluorescent material to form a specific light color performance result.

The light conversion method of using LED chips to excite phosphors can realize the output of various colors of light, which is also the main way for LEDs to achieve white lighting. The basic principle is: under the action of electricity, the light emitted by the chip through the fluorescent material combines with the wavelength of the fluorescent material to form a specific light color. For example, common white light LEDs mainly use blue light chips plus yellow phosphor powder. The blue light emitted by the chip is emitted through the yellow fluorescent material, and the blue and yellow light are combined to form a white light performance effect.

However, at present, when LEDs are used, they often encounter problems of yellow circles and light spots. The yellow circles and light spots of LEDs directly affect the lighting effect. One of the reasons for the yellow circle and light spot is the structured light of the bracket and the chip. The photometric emission of the chip is relatively complicated, and it cannot directly stimulate the peripheral phosphor to emit light. After multiple diffuse reflections, it mixes with the phosphor to emit light, and due to the refraction of the lens The color temperature of the white light produced on the outside of the chip and the center of the chip is different, resulting in a yellow circle.

Another cause of yellow circles and spots is phosphor. At present, the most widely used yellow phosphors are YAG series phosphors. The D50 of this series of phosphors is above 17um, the particles are large, the separation is serious, and the particle fluidity is poor. These are the main reasons for the light spots. Because the refractive index of phosphor is greater than or equal to 1.85, which is different from that of silica gel, the refractive index of disilica gel is generally around 1.5. Due to the mismatch of the refractive index between the two, and the size of the phosphor particles is much larger than the light scattering limit, the wavelength of the scattered light is inconsistent with the incident light, so there is light scattering on the surface of the phosphor particles, which destroys the uniformity of the light output, and then appears yellow. lock up.

Summary of the invention: In view of the above-mentioned defects, the object of the present invention is to provide a LED fluorescent glue and an LED bracket, so that the LED can emit light more uniformly, effectively improve the quality of light color, and better solve the yellow circle problem.

The invention is a high-power LED package, including LED light-emitting chips, LED brackets, fluorescent glue coated on the surface of the chip, and a lens above the bracket. The thickness of the fluorescent glue coated on the surface of the chip is greater than that on the side of the chip. Form an arc, and its arc is consistent with the lens arc. The fluorescent glue is mixed by adding small particles to the large particle phosphor, and the mixed phosphor and silica gel are combined and stirred for a period of time before vacuuming.

The weight of the large-particle phosphor is a, and the weight of the small-particle phosphor is b. The ratio between a and b is a/b=(a+b)/a or a ² =bc, where c=a+b, a/b =1.5~1.7.

The above-mentioned high-power LED package is characterized in that the angle α formed by the wall of the bracket bowl and the bottom of the cup is 40°-50°, and the height h of the bowl is 0.3mm-0.45mm.

The chip size is 35mil×35mil～45mil×45mil

The LED bracket of the present invention can make the maximum photometry of the chip pass through the slope of the bowl cup, and after only one reflection, it is close to parallel to the light beam on the surface of the chip, and the light is emitted at 80-100°, ensuring that the photometry and the light emission of the chip surface are consistent, and directly with the phosphor Mixed glow. The depth of the bowl of the LED bracket matches the slope of the wall of the bowl, that is, the angle α is formed between the wall of the bowl and the bottom of the cup, which can better evenly distribute the fluorescent glue coated on the side of the chip.

By adding small particles into the large-particle fluorescent powder, the refractive index of silica gel can be increased to above 1.8, light scattering can be reduced, the quality of light color can be effectively improved, and the problem of light spots can be better solved. Small-sized particles are added to phosphors with larger particle sizes to better match the wavelength emitted by the large particles with the wavelength of the chip to form white light, and the refractive index after mixing is closer to the refractive index of silica gel, reducing light scattering. Effectively improve the uniformity of phosphor powder, improve the quality of light color, and repair light spots.

Description of drawings

Figure 1 is a flow chart of LED packaging steps;

Figure 2 Schematic diagram of test screen and LED position;

Figure 3 is a top view of the bracket;

Fig. 4 is a sectional view of the bracket;

Fig. 5 is a schematic diagram of light output from the side of the chip;

Fig. 6 is a schematic diagram of phosphor powder mixing process;

Figure 7 is an enlarged view of phosphor surface coating and lens coverage.

Detailed ways:

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

Usually LED packaging is to connect the leads to the electrodes of the LED chip to ensure the electrical and mechanical connection between the semiconductor chip and the underlying circuit, and at the same time protect the LED chip from mechanical, heat, moisture and other external shocks , and play a role in improving the luminous efficiency. Referring to Figure 1, a brief description of the LED packaging steps is as follows:

1. Die bonding

The light-emitting chip is fixed on a special support with silver glue, and is cured by baking and heating.

2. Welding wire

Connect the outer leads to the electrodes of the LED chip.

3. Glue matching

Mix the fluorescent powder with large and small particles and silica gel in proportion, stir evenly for 10-15 minutes, and vacuum for 20 minutes.

4. Dot fluorescent glue

Use a dispensing pillow to dispense the fluorescent glue to the center of the bracket, allowing it to evenly cover the surface of the chip.

5. Baking

The purpose of baking is to cure the fluorescent glue, and the baking requires temperature monitoring to prevent bad batches. The baking temperature of fluorescent glue is generally controlled at 150°C, and the baking time is 30 minutes. It can be adjusted according to the actual situation.

6. Cover lens

Use a professional cap lens machine to automatically cap the lens on the LED chip.

7. Glue filling

Inject the semi-finished product with the covered lens into the filled silicone

8. Baking

To fully cure the filled silica gel, the general condition is 120°C, and the baking time is 20 minutes.

9. Spectral color separation

Test the packaged high-power finished product, including leakage test, and test parameters such as color temperature, luminous flux, chromaticity coordinates X/Y, and color rendering index.

The present invention implements and manufactures a 1W white light LED, which is driven by a 350mA constant current power supply with a voltage of 3.0-3.4V.

The light spot experiment test platform tests the color coordinates of 9 points of each LED through 9 points to judge the spatial uniformity of the light emitted by a single LED in all directions.

Experimental conditions: Driven by a 350mA constant current power supply, the voltage is about 3.3V. The distance between the LED and the screen is 60cm, and the tool used for the test is: CHROMA METER CS-100MINOLTA color difference meter.

The dispersion of the chromaticity coordinates can be expressed by the standard deviation of the chromaticity coordinates of the 9 test points of each LED. Let the chromaticity coordinates of the 9 test points be (X _i , Y _i ) (i=1, 2,… , 9), the color coordinate mean value of 9 test points is (-X,-Y), then the standard deviation is δ

$\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; =</span>\sqrt{\frac{\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 9</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; [</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; no</span>}}}$

Generally, if the standard deviation δ value is below 0.01, it is not easy for the human eye to distinguish the difference in chromaticity, indicating that the light color is uniform.

The experimental test platform is built in a dark room to reduce the influence of ambient light. First fix the LED on the wall, and place a white screen directly in front of it. The height of the center of the screen is the same as that of the LED, and the screen is parallel to the wall. For the convenience of testing and statistics, we selected 9 points forming a square as representative measuring points. Refer to FIG. 2 for the positions of the test screen 50 and the LED 100 .

According to the experimental requirements, an LED chip support 10 is manufactured. The top view of the support is shown in FIG. 3 . The cup wall of the support bowl 20 forms an angle α with the bottom of the cup. See FIG. 4 for the cross-sectional view of the support. Figure 5 is a schematic diagram of the light output from the side of the chip. According to the law of reflection, θi=θr (θincident angle, θr reflection angle), the normal line 5 is perpendicular to the cup wall, and the incident light 4 becomes the outgoing light 6 after reflection. The depth h of the bowl is the cup The vertical height between the highest point of the wall and the bottom of the cup.

At the same time, in order to more effectively suppress the heterochromatic aperture or light spot that is formed after the light passes through the lens, the present invention also mixes small particles into the large particle phosphor powder, wherein the radius of the large particle phosphor powder 60 is that of the small particle phosphor powder 70 1.5 times, combine the mixed fluorescent powder 90 and silica gel 80 for 10-15 minutes, then vacuumize to form fluorescent glue 7, and then coat it on the bracket 10. See Figure 6 for a schematic diagram of the mixing process.

Example 1

The angle α is 40°, the depth h of the bowl is 0.3 mm, and the LED light-emitting chip 1 is fixed on the bracket 10 with silver glue. And bake and heat to cure, wherein the chip size is 35mil×35mil; then solder the gold wire 2 to the positive and negative electrodes of the chip 1; coat the fluorescent glue 7 on the surface of the chip 1, in order to effectively suppress the refraction of the light after passing through the lens 9 The heterochromatic aperture or light spot is coated on the surface of the chip 1 with a thickness greater than that on the side of the chip, but the coating forms an arc for some reason, and its arc is consistent with the arc of the covered lens, and it is baked and formed, and covered on the bracket The upper lens 9 is filled with silica gel 8 and baked for molding. For the enlarged view of phosphor surface coating and lens coverage, see FIG. 7 .

Example 2

The angle α is 45°, the depth h of the bowl is 0.35 mm, and the LED light-emitting chip 1 is fixed on the bracket 10 with silver glue. And baked and heated to cure, the size of the chip is 38mil×38mil; then the gold wire 2 is soldered to the positive and negative electrodes of the chip 1; the fluorescent glue 7 is coated on the surface of the chip 1, in order to effectively prevent the light from passing through the lens 9 and form the refraction The heterochromatic aperture or light spot is coated on the surface of the chip 1 with a thickness greater than that on the side of the chip, but the coating forms an arc for some reason, and its arc is consistent with the arc of the covered lens, and it is baked and formed, and covered on the bracket The upper lens 9 is filled with silica gel 8 and baked for molding.

Example 3

The angle α is 50°, the depth h of the bowl is 0.45 mm, and the LED light-emitting chip 1 is fixed on the bracket 10 with silver glue. And bake and heat to cure, wherein the chip size is 45mil×45mil; then solder the gold wire 2 to the positive and negative electrodes of the chip 1; coat the fluorescent glue 7 on the surface of the chip 1, in order to effectively suppress the refraction of the light after passing through the lens 9 The heterochromatic aperture or light spot is coated on the surface of the chip 1 with a thickness greater than that on the side of the chip, but the coating forms an arc for some reason, and its arc is consistent with the arc of the covered lens, and it is baked and formed, and covered on the bracket The upper lens 9 is filled with silica gel 8 and baked for molding.

On the experimental surface, when the angle α=40°～50°, the incident light 4 forms an angle of 80～100° with the reflected light, and after one reflection, it can be nearly parallel to the light color of the chip surface, ensuring that the side light and the chip surface light are emitted uniformly The light is emitted at 80-100°, and it is directly mixed with phosphor to emit light. The depth of the bowl h=0.3mm～0.45mm, which can better match the angle α of the bowl, so that the phosphor powder coated on the side of the chip can be distributed.

Let the large particle be a, and the small particle be b. After the following experiments with different ratios of a/b, the results of the nine-point spot test are passed.

a/b 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 δ 0.1348 0.0864 0.0145 0.0072 0.0074 0.0083 0.0234 0.0217

Experiments show that the ratio of large particle phosphor to small particle meets the following relationship a/b=(a+b)/a or a ² =bc, where c=a+b, a/b=1.5～1.7 is a better ratio . After mixing large particles and small particle phosphors, the precipitation rate of large particles is faster than that of small particle phosphors, and the use of high-grade silica gel has the characteristics of inhibiting the precipitation of large particles, which effectively ensures the uniform distribution of large and small particles. After mixing The refractive index of the silica gel is closer to the refractive index of silica gel, which increases the refractive index of silica gel to above 1.8, reduces light scattering, effectively improves the uniformity of phosphor powder, improves the quality of light color, and repairs light spots.

The LED bracket of the present invention can make the maximum photometry of the chip pass through the slope of the bowl cup, and after only one reflection, it is unified with the light emission on the surface of the chip at 80-100°, ensuring that the side light and the light emission on the surface of the chip are unified, and directly mixed with the phosphor to emit light . The depth of the bowl of the LED bracket matches the wall of the bowl for taking drugs, that is, the wall of the bowl and the bottom of the cup form an angle α, which can better evenly distribute the phosphor powder coated on the side of the chip.

At the same time, by adding small particles to the large particle phosphor, it can effectively ensure the uniform distribution of large and small particles, and the refractive index after mixing is closer to the refractive index of silica gel, so that the refractive index of silica gel can be increased to above 1.8, reducing the three colors of light, effectively Maximize the uniformity of rigid distribution, improve the quality of light and color, and repair the spot.

Claims (3)

1. a high-power LED encapsulation structure, comprise LED luminescence chip, have a bowl cup-shaped groove LED support, lens are had above chip surface coating fluorescent glue, support, fluorescent glue is coated in chip surface position thickness and is greater than sides of chip position, that coating fluorescent glue forms arc, its radian is consistent with lens radian, has filling gel between lens and chip, it is characterized in that:

Described fluorescent glue is by adding granule mixing at bulky grain fluorescent material, bulky grain fluorescent material D50 is 1.5 times of small size salt, carries out vacuumizing process and formed after fluorescent material after mixing and silica gel are combined stirring a period of time;

Described bulky grain fluorescent material weight is a, and small size salt weight is the proportionate relationship of b, a and b is a/b=(a+b)/a or a ²=bc, wherein c=a+b, a/b=1.5 ~ 1.7.

2. a kind of high-power LED encapsulation as claimed in claim 1, is characterized in that, the angle [alpha] formed at the bottom of described support bowl cup wall of cup and cup is 40 °-50 °, and bowl cup height h is 0.3mm-0.45mm.

3. a kind of high-power LED encapsulation structure as claimed in claim 2, is characterized in that, described chip size is 35mil × 35mil ~ 45mil × 45mil.