KR102131666B1 - Method of forming foaming ink reflector on printed circuit board by printing process - Google Patents

Abstract

The present invention relates to a foaming ink reflector and a method for forming the same on a printed circuit board by a printing process, which can improve light efficiency by effectively reflecting nearby horizontal light emitted from four surfaces out of five surfaces of a CSP LED, by forming a foaming ink reflector on a printed circuit board around a CSP LED light source by a printing process, wherein the foaming ink reflector comprises: one or more colorants selected from an acrylic resin, a PVC resin, an epoxy resin, a urethane resin, and a silicone resin; white pigment; a foaming agent; and pearl powder.

Description

Foaming ink reflector and a method of forming the same on a printed circuit board by a printing method{Method of forming foaming ink reflector on printed circuit board by printing process}

The present invention is any one or two or more colorants selected from acrylic resin, PVC resin, epoxy resin, urethane resin or silicone resin; White pigment; blowing agent; By forming a foamed ink reflector consisting of pearl powder on a printed circuit board (PCB) around a CSP LED light source using a printing method, it effectively reflects light close to the horizontal light emitted from 4 of 5 of the CSP LED's sides. A foam ink reflector capable of improving light efficiency and a method of forming the same on a printed circuit board by a printing method.

Currently used LED is generally composed of a chip having a light emitting source through a P-N semiconductor layer, a lead frame for drawing an electrical contact to the outside, a housing, and a phosphor. In order to improve the light extraction efficiency of the chip, as shown in FIG. 1, generally, a reflector (reflector) is provided inside the housing.

In order to improve the efficiency and improve the reliability of the LED light source, the LED chip was developed in the order of Later LED Chip, Vertical LED Chip, Flip LED Chip and White Flip Chip, as shown in FIG. 2. Currently, the development of a flip chip type is actively underway, and such a structure is being mass-produced by being reflected in a high power LED of several W class.

However, the technical change of the LED caused the user of the corresponding light source (LED) to receive an unwanted change among the changed characteristics. The most representative of them is the reduction of the light efficiency of a BLU (back light unit) or lighting fixture.

As shown in FIG. 3, a white light-emitting LED (CSP LED-chipscale LED) treated with a phosphor on a flip chip surface has a five-sided light emitting structure. The white light-emitting CSP LED has a high level of light emitted in the horizontal direction from the mounting surface of the printed circuit board, so the light has a light distribution characteristic different from that of the existing LED. CSP LEDs emit more than 25% of the total amount of light toward the bottom and sides.

The BLU or lighting luminaire using the white light-emitting CSP LED has a light loss as shown in FIG. 4. The light parallel to the circuit board passes through the reflection process in the interior space several times and reaches the illumination cover or diffusion plate and is drawn out.

In many reflection processes, light absorption loss occurs depending on the state of the reflector, resulting in light loss. In addition, when light is incident at an angle corresponding to the surface reflection angle (θ1) of the lighting cover or the diffuser, the light is also not extracted to the outside but is taken out through a plurality of reflection processes inside the BLU or lighting luminaire. It causes light loss.

In order for LED emitting light to be drawn out while reducing light loss to the outside of the BLU or lighting fixture, the path of light parallel to the printed circuit board should be directed to the lighting cover or diffusion plate with only one possible reflection.

In addition, as shown in FIG. 4, the angle of light incident on the illumination cover or the diffusion plate is formed to be greater than or equal to the angle θ2 in consideration of the surface reflection angle to increase light efficiency.

In order to objectively grasp such a light loss, when a reflective structure was formed around the CSP LED, the amount of light capable of changing the direction of light through the reflective structure was calculated. (FIG. 5) CSP LED's directivity angle 120 The amount of light outside the ° range is about 28%. This amount of light is drawn out by repeating many reflections inside the BLU or lighting fixture. This withdrawal leads directly to loss.

Therefore, in the present invention, in order to improve the problems of the prior art and minimize light loss, a description is given of a technique for forming a foamed ink reflector and a method of forming the same on a printed circuit board by a printing method.

Republic of Korea Registered Patent 10-1768371 (Registration Date 2017.08.08) Republic of Korea Patent Publication 10-2017-0040761 (published on 2017.04.13) Republic of Korea Patent Publication 10-2018-0127292 (published on November 28, 2018) Republic of Korea Registered Patent 10-1807398 (Registration Date 2017.12.04)

The present invention is any one or two or more colorants selected from acrylic resin, PVC resin, epoxy resin, urethane resin or silicone resin; White pigment; blowing agent; By forming a foamed ink reflector consisting of pearl powder on a printed circuit board (PCB) around a CSP LED light source using a printing method, it effectively reflects light close to the horizontal light emitted from 4 of 5 of the CSP LED's sides. It is an object of the invention to provide a foaming ink reflector capable of improving light efficiency and a method of forming it on a printed circuit board by a printing method.

In order to achieve the above object,

The present invention is any one or two or more colorants selected from acrylic resin, PVC resin, epoxy resin, urethane resin or silicone resin; White pigment; blowing agent; It provides a foamed ink reflector, characterized in that it is a reflector formed in a tubular or hemispherical shape by foaming a white foamed ink composed of pearl powder.

Also,

Any one or two or more colorants selected from acrylic resin, PVC resin, epoxy resin, urethane resin or silicone resin; White pigment; blowing agent; Mixing pearl powder; preparing a white foaming ink,

Printing the white foam ink on a printed circuit board (PCB) through a screen print or mask print process,

Provides a method for forming a foamed ink reflector on a printed circuit board by a printing method, comprising heating and foaming the white foam ink printed on the printed circuit board (PCB) at a temperature of 120 to 240°C. .

The foamed ink reflector according to the present invention has the following effects.

first. By reflecting light close to the horizontal light emitted from four of the five surfaces of the CSP LED through a tubular or hemispherical foam ink reflector, the light efficiency is improved through a low cost and simple process.

second. COB LED, Bulb, PAR Type, Down Light, High-Bay, Spot Light, Security Light, Street Light, etc. can be applied to various lights to improve the light efficiency, especially in COB type light sources. Have

third. The CSP has a light beam parallel to the PCB surface due to the five-sided light emission, and a separate reflector is required to improve the light efficiency by applying the CSP to the LED lighting. Compared to the method presented in the present invention, forming the reflector on the PCB surface in a conventional manner, in the present invention, an integral reflector can be effectively formed on the PCB surface at a very low cost. It has the advantage that it can provide an effect of improving light efficiency.

fourth. By providing a CSP structure LED package with improved light efficiency, it has the effect of increasing light efficiency, improving heat loss, improving high temperature reliability, improving heat resistance, cost, and providing small size packaging.

The increase in light efficiency means that the light efficiency is higher than the current Later LED Chip. The P-N chanel take-out terminal has a structure that does not interfere with light extraction, which can lower the light loss.

The improvement of the heat loss means that the chip size can be largely applied at an equal price, thereby lowering the heating value.

The high temperature reliability means that the current Later or Vertical LED Chip has a wire bonding structure, whereas the CSP has high temperature reliability because there is no wire bonding based on the flip chip.

The cost improvement refers to a reduction in raw material usage due to omission of the mold package.

The provision of the small size packaging means that the light source size is reduced from the previous 5050, 3535 size to 1414 size or less.

1 is a view showing a conventional LED package structure.
Figure 2 is a view showing the development trend (LED Technology Trends) of the conventional LED technology.
Figure 3 is a view showing a conventional white light emitting CSP LED structure.
4 is a view showing a light loss process of a BLU or lighting fixture using a conventional white light-emitting CSP LED.
5 is a view showing the amount of light that can switch the direction of light through the reflective structure when a reflective structure is formed around the CSP LED.
6 is a view showing the foaming process of the foamed ink reflector according to the present invention.
7 is a view showing a printing pattern of a tubular foamed ink reflector according to the present invention.
8 is another view showing a printing pattern of the tubular foaming ink reflector according to the present invention.
Figure 9 is a side view showing a hemispherical foam ink reflector according to the present invention.
10 is a view showing various structures for arranging a hemispherical foam ink reflector according to the present invention around a light source.
FIG. 11 is a view showing a mathematical relationship with respect to a relationship in which a reflective structure is formed around a CSP LED (distance X and height Y of a reflective structure) when an appropriate angle that does not cause surface reflection on the lighting cover or diffusion plate is selected.
12 is a view showing a sample used in the light efficiency change test of the foamed ink reflector according to the present invention.
13 is a measurement data of the foamed ink reflector according to the present invention.
14 is a graph graphing the measurement data of FIG. 13.
15 is a photograph that can directly check the measurement data of FIGS. 13 and 14.
16 is a view showing the relationship between the surface brightness of the light extraction surface of the diffuser luminaire outer surface with respect to the angle (θ3, 4) of the reflective surface.

Hereinafter, the foaming ink reflector according to the present invention and a method of forming the same on a printed circuit board by a printing method will be described in detail with the drawings.

The foamed ink reflector according to the present invention is printed on the surface of a printed circuit board (PCB) and reflects light emitted from an LED light source to improve light efficiency, and is formed by thermal expansion by printing white foaming ink and then heating it at high temperature to foam it. .

At this time, the white foaming ink may be any one or two or more colorants selected from acrylic resin, PVC resin, epoxy resin, urethane resin or silicone resin 20.0 to 80.0 wt%; White pigment 0.1-25.0 wt%; Blowing agent 5.0-35.0 wt%; Pearl powder is composed of 1.0 ~ 25.0 wt%;.

The colorant is a paint containing a pigment, and is a liquid component that forms a coating film by adhering a solid component pigment to a painted surface, and any one or two selected from acrylic resin, PVC resin, epoxy resin, urethane resin or silicone resin. Use more than species.

When the amount of the colorant used is less than 20.0 wt%, there is a problem that the curing is completed and easily breaks against external impact when forming a structure, and when it exceeds 80.0 wt%, there is a problem that the volume ratio of foam formation cannot be formed high. , The amount of the colorant is preferably limited to within the range of 20.0 to 80.0 wt% of the total components of the white foam ink.

The white pigment is a powder or a liquid, and determines color and reflects light from the structure. When the amount of the white pigment used is less than 0.1 wt%, there is a problem that the light reflection function is not effectively performed due to the lack of white expression of the resulting structure, and when it exceeds 25.0 wt%, the surface of the foamed form of the product is evenly Since there is a problem that can not be generated, the amount of the white pigment is preferably limited to within the range of 0.1 to 25.0 wt% of the total components of the white foam ink.

The foaming agent is used for foaming during high-temperature heating, and uses gasification of hydrocarbons and a method of coating the thermoplastic resin surface with an inert inorganic powder. In addition, in the form of powder granules, it serves to increase the volume at high temperature conditions when forming structures.
As a specific example of the foaming agent, a thermally expandable microcapsule is used.

When the amount of the blowing agent used is less than 5.0 wt%, there is a problem that the volume ratio of foaming of the product is insufficient, and when it exceeds 35.0 wt%, the problem that the surface of the product cannot be evenly produced and the strength of the product is lowered. Therefore, the amount of the blowing agent is preferably limited to within the range of 5.0 to 35.0 wt% of the total components of the white foaming ink.

The pearl powder is used to increase the reflectance, and if the amount used is less than 1.0 wt%, the effect of reflection efficiency is insignificant, and when it exceeds 25.0 wt%, the conditions and product characteristics of the colorant are changed. Since there is a problem causing a change in strength, it is preferable to limit the amount of the pearl powder to be used within a range of 1.0 to 25.0 wt% of the total components of the white foam ink.

Specific blending examples of the white foam ink are shown in Table 1 below.

Formulation Example 1 Formulation Example 2 Formulation Example 3 Formulation Example 4 Formulation Example 5 medium 50.0 wt% 56.4 wt% 60.7 wt% 65.3 wt% 69.4 wt% White pigment 24.3 wt% 21.4 wt% 19.4 wt% 16.5 wt% 11.4 wt% Thermally expandable micro capsule
23.7 wt%
20.3 wt%
18.1 wt%
16.3 wt%
16.1 wt% Pearl powder 2.0 wt% 1.9 wt% 1.8 wt% 1.9 wt% 3.1 wt% Sum 100.0 wt% 100.0 wt% 100.0 wt% 100.0 wt% 100.0 wt%

The foamed ink reflector using the white foamed ink is integrally formed on the surface of the printed circuit board (PCB) through the following process.

That is, any one or two or more colorants selected from acrylic resin, PVC resin, epoxy resin, urethane resin, or silicone resin; White pigment; blowing agent; Mixing pearl powder; preparing a white foaming ink (S10),

Printing the white foaming ink on a printed circuit board (PCB) through a screen print or mask print process (S20),

The foamed ink reflector is integrally formed on the surface of the printed circuit board (PCB) through the step (S30) of heating and foaming the white foamed ink printed on the printed circuit board (PCB) at a temperature of 120 to 240°C.

1. White foaming ink manufacturing step (S10)

The white foaming ink is 20.0 ~ 80.0 wt% of any one or two or more colorants selected from acrylic resin, PVC resin, epoxy resin, urethane resin or silicone resin; White pigment 0.1-25.0 wt%; Blowing agent 5.0-35.0 wt%; Pearl powder 1.0 ~ 25.0 wt%; is prepared by mixing.

2. Printing step (S20)

The white foaming ink prepared in the previous step (S10) is printed on the surface of the printed circuit board (PCB) through a screen print or mask print process at room temperature.

The printing step

Reflector printing type: In the case of silkscreen (mesh) printing, reflective ink printing is not necessary, but in the case of printing using a metal mask, a dividing structure must be formed. When using a metal mask, it is used when the printing thickness of the ink needs to be made high.

3. Foaming step (S30)

The white foam ink printed on the surface of the printed circuit board (PCB) through the previous step (S20) is thermally expanded by heating at a temperature of 120 to 240° C. for 2 to 30 minutes to form a tubular or hemispherical foam ink reflector.

The foamed ink reflector thus formed is integral with the surface of the printed circuit board (PCB).

More specifically, as shown in FIG. 6, a white foam ink printed on the surface of a printed circuit board (PCB) is applied, a CSP LED component is mounted, and then a foam mold is seated to form a high-temperature environment SMT Reflow. Ink foaming proceeds through a process.

After the ink foaming is completed, the product is completed by naturally cooling at room temperature and then removing the foamed mold to create a reflective structure.

The foaming ink reflector 1 is formed in a tubular or hemispherical shape around the LED light source 200 of the PCB surface 100.

The tubular foaming ink reflector 1 forms an arrangement structure that forms a band of a circular or polygonal shape with a predetermined distance around the LED light source 200, the arrangement of which is shown in FIGS. 7 and 8 Various shapes and patterns can be achieved.

The pattern of the foamed ink reflector 1 shown in FIGS. 7 and 8 is that ink forming a band of a circular or polygonal shape through printing is swollen through a foaming process to form a tube shape, as shown in FIG. 7. Likewise, it is possible to achieve a divided structure such as an undivided structure and a two-part, four-part and six-part structure. In addition, as shown in FIG. 8, a method of reducing the amount of printing ink used by applying the continuous pattern method is also possible.

The foaming ink reflector 1 is formed in a tubular or hemispherical shape around the LED light source 200 of the PCB surface 100, as shown in FIG. 9, at an angle close to the PCB surface 100 from the LED light source. It has the function of improving light efficiency by reflecting the emitted light.

The hemispherical foam ink reflector 1 forms an arrangement structure selected from a circular array or a polygonal array around the LED light source 200 (FIG. 10).

As shown in Fig. 10 as a specific example, the arrangement structure may be arranged in a variety of forms, such as triangular, square, hexagon, and circular shapes, in which the form of the foamed ink reflector 1 is centered around the LED light source 200. Do.

At this time, under the condition that the distance between the center of the LED light source 200 and the center of the tubular or hemispherical foam ink reflector 1 is all arranged identically, an arrangement structure selected from circular arrangement or polygonal arrangement is formed.

Depending on the arrangement structure, ink usage and light efficiency are affected, so it is most preferable to form a circular, square or hexagonal arrangement in close proximity to the light source.

An element considered in forming the tubular or hemispherical foam ink reflector 1 is a bottom surface where the straight line distance X from the outermost surface of the LED light source 200 and the tubular or hemispherical foam ink reflector 1 are in contact. And the height (Y) between the highest points of the tubular or hemispherical foam ink reflector (1).

FIG. 11 shows a mathematical relationship with respect to a relationship of forming a reflective structure around a CSP LED (distance X and height Y of a reflective structure) when an appropriate angle that does not cause surface reflection on the lighting cover or diffusion plate is selected. In order to obtain the light emission angle, it is possible to adjust through the θ value of FIG. 11.

In the normal case, the range of θ = 30 to 35 ° is practically suitable, and if it is smaller than that, the possibility that light is reflected inward from the surface of the light cover or diffuser light entrance portion increases.

When the angle is large, there is a problem in that the light uniformity of the light cover of the lighting cover or the diffuser plate is lowered or the unevenness of light increases, so that the arrangement interval of the LEDs must be narrowed.

When the distance between the point light source (LED) and the printed foam ink reflector 1 is X and the height of the foam ink reflector 1 is Y, the relationship for obtaining a specific light distribution angle can be obtained as a constant (ξ). have.

tanθ = Y/X, tan35° ≒ 0.7, ∴ Y35° ≒ 0.7X, Y30° ≒ 0.58X

That is, when the light distribution angle is 110 ° (Y35 °) is 0.7, when 120 ° (Y30 °) is 0.58. Accordingly, a relationship for obtaining a specific light distribution angle can be obtained within a constant (ξ) of 0.58 to 0.7.

The angle of the reflective surface of the tubular or hemispherical foam ink reflector 1 associated with the constant ξ is maintained at 45° to 60°. At this time, if the angle is less than 45°, the density of light reaching the diffuser plate is high, and thus there is a problem of light staining. If it exceeds 60°, when the reflective structure is formed due to the increase in the amount of foamed ink used, it comes into contact with the circuit board. Since there is a problem of an increase in the area of the bottom of the structure, it is preferable to limit the angle of the reflection surface within a range of 45° to 60°.

Hereinafter, a change in light efficiency of the foamed ink reflector 1 according to the present invention will be described through a test.

1. Test conditions

■ Test Name: Evaluation of light efficiency change when forming reflective structure through foaming ink on PCB

■ Equipment used: DC power supply (Tektronix PS280), DMM (Mastech MAS-345), illuminometer

■ Sample: CSP Module, CSP+Reflector Module, Form INK (NP-PU 4706 White) (Figure 10)

■ Test method: After placing the diffuser plate (PS 1.5T) on a certain distance of the top surface of the LED module, measure the placement of the light diffusing surface illuminometer sensor (aligned to the center of the LED module)

2. Test results

Result data measured according to the test conditions are as shown in FIG. 13.

As a result of comparing the test example (CSP+Reflector) and the comparative example (CSP) according to the present invention, it was confirmed that the increase is as low as 8.8% to as much as 21.2%.

14 is a graph of the result data of FIG. 13. When the CSP LED light output increased (If [mA] increased), the effect of improving the light efficiency of the LED module with a reflector tended to increase slightly. And it was confirmed that the illuminance of 12.6% (@0.355W/CSP LED) has a synergistic effect when forming a reflector in the CSP LED Module. 15 is a photograph that can actually confirm such a change.

Fig. 16 shows the relationship of the surface luminance of the light extraction surface (outer surface of the diffuser luminaire) with respect to the angle (θ3, 4) of the reflective surface.

In FIG. 16A, when the angle of the reflecting surface of the reflector is θ3, the larger the angle of the reflecting surface, the higher the brightness of the light extraction surface corresponding to the area of the diffuser plate, which may lead to an unreasonable result in terms of luminance uniformity. As the area of the B area is relatively reflected and drawn out, it is possible to obtain reasonable results for the luminance uniformity of the diffuser plate light extraction surface and the factors for light irregularity.

That is, if the CSP LED corresponding to the point light source has a height of about 0.6 mm and is printed on the component mounting position as close as possible, forming a reflective surface with a height of about 1.5 mm can obtain an effect on improving light efficiency, but forming an appropriate reflective surface. If is not considered, it indicates that light stains may appear on the surface of the diffuser plate. The change value may vary depending on the material and surface condition of the reflective surface, but it was found through experiments that the θ3 value is usually 45 degrees or less when the separation distance between the light source and the diffuser plate is within 40 mm.

By using the foamed ink reflector according to the present invention, it effectively reflects light close to the horizontal light emitted from 4 of 5 surfaces of the CSP, and has an effect of improving light efficiency of 13% or more compared to the existing one. It is easy to form and has great industrial applicability.

1: Foam ink reflector
100: PCB surface
200: LED light source

Claims (7)

Any one or two or more colorants selected from acrylic resin, PVC resin, epoxy resin, urethane resin or silicone resin; White pigment; blowing agent; In a reflector formed in a tubular or hemispherical shape by foaming a white foaming ink composed of pearl powder;

The white foaming ink is 20.0 ~ 80.0 wt% of any one or two or more colorants selected from acrylic resin, PVC resin, epoxy resin, urethane resin or silicone resin; White pigment 0.1-25.0 wt%; Blowing agent 5.0-35.0 wt%; Foam powder reflector, characterized in that consisting of 1.0 ~ 25.0 wt% pearl powder.
delete delete delete delete delete A method of printing a reflector around a LED light source on a printed circuit board (PCB),
20.0 to 80.0 wt% of any one or two or more colorants selected from acrylic resin, PVC resin, epoxy resin, urethane resin or silicone resin; White pigment 0.1-25.0 wt%; Blowing agent 5.0-35.0 wt%; Mixing pearl powder 1.0 ~ 25.0 wt%; to prepare a white foaming ink,
Printing the white foaming ink around a LED light source of a printed circuit board (PCB) through a screen print or mask print process;
A method of forming a foamed ink reflector for an LED light source on a printed circuit board by printing the white foam ink printed on the printed circuit board (PCB) at a temperature of 120 to 240° C. to foam the foam. .

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