LED based on COB substrate and preparation method thereof

Abstract

The invention discloses an LED based on a COB substrate and a preparation method thereof, and relates to the field of light emitting devices, a substrate layer of the LED is composed of a second mirror surface aluminum plate and a first mirror surface aluminum plate, the second mirror surface aluminum plate is provided with a plurality of through holes, the lower ends of the through holes lead to the upper surface of the first mirror surface aluminum plate to form concave lamp positions, and concave lamp positions of LED chips are placed in the concave lamp positions. The first mirror surface aluminum plate is used as the bottom surface of the concave lamp position, and meanwhile, the second mirror surface aluminum plate is used as the bottom surface of the bowl cup, so that the high reflection surface of light rays is increased, and the brightness of the LED is improved. Meanwhile, due to the fact that the LED chip is arranged at the concave lamp position, heat generated by the fluorescent glue layer and the LED chip can be diffused from the bottom through the first mirror face aluminum plate and can also be diffused transversely through the second mirror face aluminum plate, and the heat dissipation effect is good. And the concave lamp position can increase the depth of the bowl cup, so that a lower box dam and less fluorescent glue are allowed to be used under the condition of ensuring that the bonding wire is not exposed, and a thinner LED product is realized.

Description

Technical Field

[0001] The present invention relates to the field of light-emitting devices, and in particular to an LED based on a COB substrate and a preparation method thereof. Background Art

[0002] With the widespread application of LED in the application market, the application environment has become more complex, harsh, and changeable, and the requirements for light sources have become higher and higher, requiring higher brightness, higher power density, higher light efficiency, better heat dissipation, better light color, better pressure resistance, etc. At this stage, the product structure of LED light sources has basically been finalized. Whether it is SMD or COB products, the space for changes in structure and materials used is gradually decreasing, and the main focus is on the improvement of phosphors and chips. The improvement speed of the bracket or substrate has gradually slowed down, and the improvement ratio of heat dissipation capacity and light color is very low. This application mainly carries out a composite design for the COB substrate, assisted by the preparation process, while reducing the thickness of the LED product, improving the heat dissipation capacity and light reflection ability of the light source. Summary of the invention

[0003] The purpose of the present invention is to provide an LED based on a COB substrate and a preparation method thereof, which aims to overcome the above-mentioned problems existing in the prior art.

[0004] To achieve the above object, the present invention provides the following technical solutions: A LED based on a COB substrate comprises, from bottom to top, a substrate layer and a bonding layer, wherein the bonding layer is composed of a heat-conducting insulating layer and a circuit layer on the heat-conducting insulating layer, a hollow portion is provided in the middle of the bonding layer, the lower end of the hollow portion leads to the substrate layer, forming a bowl with the substrate layer as the bottom, and the bowl is filled with a fluorescent glue layer; the substrate layer is formed by a second mirror aluminum plate and a first mirror aluminum plate bonded to each other with pure glue, the second mirror aluminum plate is provided with a plurality of through holes in the bottom area of ​​the bowl, the lower ends of the through holes lead to the upper surface of the first mirror aluminum plate, forming a concave lamp position; at least one LED chip is placed in the concave lamp position.

[0005] Furthermore, the thickness of the second mirror aluminum plate is 0.25mm-0.35mm, and the distance between the side wall of the through hole and the LED chip placed therein is greater than 0.20mm. (The total distance between the second mirror aluminum plate and the first mirror aluminum plate after bonding is about 0.7mm) Furthermore, the thickness of the second mirror aluminum plate is 0.3 mm, and the distance between the side wall of the through hole and the LED chip placed therein is 0.25 mm.

[0006] Furthermore, the side walls of the through hole are arranged to be inclined outward from bottom to top.

[0007] Furthermore, the through hole is punched from top to bottom using a stamping process.

[0008] A method for preparing an LED having a structure as described above, comprising the following steps: (1) A stamping process is used to stamp a mirror aluminum plate from top to bottom, and a plurality of through holes are stamped out on the mirror aluminum plate to obtain a second mirror aluminum plate; (2) applying pure glue on the lower surface of the second mirror aluminum plate, and bonding the second mirror aluminum plate to the upper surface of the first mirror aluminum plate through the pure glue to obtain a substrate layer; (3) preparing a bonding layer on the substrate layer to obtain a COB substrate; (4) The LED chip is fixed in the concave lamp position by a die-bonding adhesive, and each LED chip and the circuit layer of the bonding layer are electrically connected by bonding wires; then, a dam is prepared on the upper surface of the COB substrate, and the dam is higher than the bonding wire; (5) Fill the cup with fluorescent glue, use a precipitation process to allow the fluorescent powder in the fluorescent glue to gather at a higher concentration on the surface of the substrate layer, and then solidify it into a fluorescent glue layer, thereby producing an LED product.

[0009] Furthermore, in the above step (1), the thickness of the mirror aluminum plate is 0.3 mm, the through hole is in the shape of an inverted truncated cone, and the upper end diameter is mm The lower end diameter is mm; where L, W and H are the length, width and height of the LED chip respectively.

[0010] Furthermore, the components of the above fluorescent glue are LUYAG535 green powder, nitride 630 red powder and low-fold A / B mixed glue.

[0011] Compared with the prior art, the present invention has the following beneficial effects: First, in the present invention, the substrate layer is composed of a second mirror aluminum plate and a first mirror aluminum plate, and the second mirror aluminum plate is provided with a plurality of through holes in the bottom area of ​​the bowl, and the lower ends of the through holes lead to the upper surface of the first mirror aluminum plate, forming a concave lamp position, and the concave lamp position in which the LED chip is placed. It can be seen that the present invention uses the high-reflectivity upper surface of the first mirror aluminum plate as the bottom surface of the concave lamp position, and uses the high-reflectivity upper surface of the second mirror aluminum plate as the bottom surface of the bowl, thereby increasing the reflection surface of the light and improving the brightness of the LED. At the same time, since the LED chip is placed in the concave lamp position, the heat generated by the fluorescent glue layer and the LED chip can be diffused from the bottom through the first mirror aluminum plate, and can also be diffused laterally through the second mirror aluminum plate, so that the heat dissipation effect is good. Moreover, the concave lamp position can increase the depth of the bowl, and under the condition of ensuring that the bonding wire is not exposed, it allows the use of a lower dam and less fluorescent glue, thereby realizing a thinner LED product.

[0012] Second, in the present invention, the thickness of the second mirror aluminum plate is 0.25mm-0.35mm, which ensures strength while facilitating the processing and forming of the through hole. The spacing between the side wall of the through hole and the LED chip placed therein is greater than 0.20mm, which facilitates the placement of the LED chip and prevents the side wall of the through hole from blocking light. In particular, the side wall of the through hole is tilted outward from bottom to top.

[0013] Thirdly, the through hole is punched from top to bottom by a stamping process, which can avoid the damage to the mirror surface of the upper surface of the first mirror aluminum plate as much as possible and ensure the light emissivity.

[0014] Fourth, after filling the cup with fluorescent glue, a precipitation process is used to allow the fluorescent powder in the fluorescent glue to gather at a higher concentration on the surface of the substrate layer, and the concave lamp position makes it easier for the fluorescent powder to cover the LED chip, improving the uniformity of the light color. In addition, the fluorescent powder is gathered at a higher concentration on the surface of the COB substrate, and the heat generated by the excited fluorescent powder can be directly dissipated through the substrate layer. Otherwise, it will have to be conducted through silica gel. The thermal conductivity of silica gel is very poor, and the efficiency of transferring heat to the substrate through silica gel is low, and it is easy to accumulate heat on the glue surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a top view of the LED in the present invention; the fluorescent glue layer is not shown in the figure.

[0016] Figure 2 For LED along Figure 1 Cross-sectional view along the AA direction; bonding wires are not shown in the figure.

[0017] Figure 3 In the present invention, the COB substrate is Figure 1 Cross-sectional view along the AA direction.

[0018] Figure 4 This is a top view of the COB substrate in the present invention. DETAILED DESCRIPTION

[0019] The specific implementation of the present invention is described below with reference to the accompanying drawings. In order to fully understand the present invention, many details are described below, but for those skilled in the art, the present invention can be implemented without these details.

[0020] like Figures 1 to 4 , an LED based on a COB substrate, comprising a substrate layer and a bonding layer 3 from bottom to top, wherein the bonding layer 3 is composed of a thermally conductive insulating layer and a circuit layer on the thermally conductive insulating layer, a hollow portion 31 is provided in the middle of the bonding layer 3, and the lower end of the hollow portion 31 leads to the substrate layer, forming a bowl cup with the substrate layer as the bottom, and the bowl cup is filled with a fluorescent glue layer 7.

[0021] like Figures 1 to 4The substrate layer is formed by bonding the second mirror aluminum plate 2 and the first mirror aluminum plate 1 to each other using pure glue (not shown in the figure). The second mirror aluminum plate 2 is provided with twenty-four through holes 21 in the bottom area of ​​the bowl. The lower end of the through hole 21 leads to the upper surface of the first mirror aluminum plate 1, forming a concave lamp position; an LED chip 5 is placed inside each concave lamp position. Of course, the number of through holes 21 can be increased or decreased as needed, and is not limited to twenty-four; each concave lamp position can also be placed with multiple LED chips 5.

[0022] like Figures 1 to 4 , each LED chip 5 is electrically connected by a bonding wire 6, and a dam 4 is provided in an annular manner around the edge of the hollow portion on the upper surface of the bonding layer 3, and the dam 4 is a part of the bowl, and a fluorescent glue layer 7 is filled in the middle. Of course, the method of connecting the LED chips 5 in series with the bonding wire 6 can be adjusted as needed, and is not limited to Figure 1 as shown in .

[0023] The high-reflectivity upper surface of the first mirror aluminum plate 1 is used as the bottom surface of the concave lamp position, and the high-reflectivity upper surface of the second mirror aluminum plate 2 is used as the bottom surface of the bowl, so as to increase the reflection surface of the light, thereby improving the brightness of the LED. At the same time, since the LED chip 5 is placed in the concave lamp position, the heat generated by the fluorescent glue layer 7 and the LED chip 5 can be diffused from the bottom through the first mirror aluminum plate 1, and can also be diffused laterally through the second mirror aluminum plate 2, so the heat dissipation effect is good. The concave lamp position can increase the depth of the bowl, and under the condition of ensuring that the bonding wire 6 is not exposed, it allows the use of a lower dam 4 and less fluorescent glue, so as to achieve a thinner LED product.

[0024] like Figures 1 to 4 The outer dimensions of the second mirror aluminum plate 2 are 13.5×13.5mm, and the thickness is 0.25mm-0.35mm. Too thick mirror aluminum plate is not conducive to the processing and forming of the through hole 21, and will also increase the production cost, while too thin mirror aluminum plate is insufficient in strength and easy to deform. Preferably, the thickness of the second mirror aluminum plate 2 is 0.3mm. The spacing between the side wall of the through hole 21 and the LED chip 5 placed therein is 0.25mm-0.35mm. Preferably, the thickness of the second mirror aluminum plate 2 is 0.3mm, plus the thickness of the pure glue, so that the total thickness of the first mirror aluminum plate 1 and the second mirror aluminum plate 2 after bonding is about 0.7mm.

[0025] Preferably, the thickness of the second mirror aluminum plate 2 is 0.3 mm, and the distance between the side wall of the through hole 21 and the LED chip 5 placed therein is 0.25 mm.

[0026] like Figures 1 to 4 The first mirror aluminum plate 1 has an outer dimension of 13.5×13.5 mm and a thickness of 0.35 mm-0.4 mm.

[0027] like Figures 1 to 4 Preferably, the first mirror aluminum plate 1 and the second mirror aluminum plate 2 are bonded to each other using white glue, and the total thickness after bonding is controlled to be about 0.7 mm.

[0028] like Figures 1 to 4 The side wall of the through hole 21 is tilted outward from bottom to top to prevent the side wall of the through hole 21 from blocking the light and facilitate the placement of the LED chip. The cross-sectional profile of the through hole 21 can be circular, rectangular or the like.

[0029] like Figures 1 to 4 Preferably, the through hole 21 is punched from top to bottom using a stamping process.

[0030] like Figures 1 to 4 A method for preparing an LED based on a COB substrate as described above comprises the following steps: (1) A mirror aluminum plate is punched from top to bottom using a stamping process, and a plurality of through holes 21 are punched out on the mirror aluminum plate to obtain a second mirror aluminum plate 2. The second mirror aluminum plate 2 has an outer dimension of 13.5×13.5 mm and a thickness of 0.3 mm. The through hole 21 is in the shape of an inverted truncated cone, and the upper and lower diameters of the through hole 21 are set according to the size of the LED chip 5. Specifically, the upper end diameter of the through hole 21 is mm The lower end diameter is mm; wherein L, W and H are the length, width and height of the LED chip 5 respectively.

[0031] (2) Apply pure glue (not shown) on the lower surface of the second mirror aluminum plate 2, and adhere the second mirror aluminum plate 2 to the upper surface of the first mirror aluminum plate 1 through the pure glue to obtain a substrate layer. The thickness of the pure glue is about 0.1 mm. The outer dimensions of the first mirror aluminum plate 1 are 13.5×13.5 mm and the thickness is 0.3 mm.

[0032] (3) A bonding layer 3 is prepared on the substrate layer to obtain a COB substrate; the bonding layer 3 is composed of a thermally conductive insulating layer and a circuit layer on the thermally conductive insulating layer, which is a conventional design of a COB substrate. A person skilled in the art can prepare a suitable bonding layer 3 as required, which will not be described in detail here. The thickness of the COB substrate is controlled to be about 0.9 mm.

[0033] (4) The LED chip 5 is fixed inside the concave lamp position by a die-bonding adhesive (not shown in the figure), and each LED chip 5 and the circuit layer of the bonding layer 3 are electrically connected by bonding wires 6; then, a dam is prepared on the upper surface of the COB substrate, and the dam 4 is higher than the bonding wires 6.

[0034] (5) Fill the cup with fluorescent glue, and use a precipitation process to allow the fluorescent powder in the fluorescent glue to gather on the surface of the substrate layer with a higher concentration, and then solidify into a fluorescent glue layer 7, thereby producing an LED product.

[0035] The precipitation process can be a centrifugal technology or a natural precipitation process, which allows the phosphor to gather at a higher concentration on the surface of the COB substrate. The heat generated by the phosphor being excited can be directly dissipated through the substrate layer. Otherwise, it will be conducted upward through the silicone. The thermal conductivity of silicone is very poor, and the efficiency of transferring heat to the substrate through silicone is low, and it is easy to accumulate heat on the surface of the glue. In addition, the phosphor can cover the LED chip, which can improve the uniformity of light color.

[0036] In a specific embodiment, the above fluorescent glue is composed of LUYAG535 green powder, nitride 630 red powder and low-refractive A / B mixed glue (i.e., AB component mixed glue with a refractive index lower than 1.4). The concentration of the fluorescent powder is 26%, and the mass ratio of LUYAG535 green powder to nitride 630 red powder in the fluorescent powder is 15.4:1.

[0037] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. An LED based on a COB substrate, comprising a COB substrate, the COB substrate comprising a substrate layer and a bonding layer from bottom to top, the bonding layer consisting of a thermally conductive insulating layer and a circuit layer on the thermally conductive insulating layer, a hollow portion is provided in the middle of the bonding layer, the lower end of the hollow portion leads to the substrate layer, forming a bowl with the substrate layer as the bottom surface, the bowl is filled with a fluorescent glue layer, characterized in that: The substrate layer is formed by bonding a second mirror aluminum plate and a first mirror aluminum plate to each other using pure glue; the second mirror aluminum plate is provided with a plurality of through holes in the bottom area of ​​the bowl; the lower ends of the through holes lead to the upper surface of the first mirror aluminum plate, forming a concave lamp position; at least one LED chip is placed in the concave lamp position.

2. The LED based on COB substrate according to claim 1, characterized in that: The thickness of the second mirror aluminum plate is 0.25 mm-0.35 mm, and the distance between the side wall of the through hole and the LED chip placed therein is greater than 0.20 mm.

3. The LED based on COB substrate according to claim 1, characterized in that: The thickness of the second mirror aluminum plate is 0.3 mm, and the distance between the side wall of the through hole and the LED chip placed therein is 0.25 mm.

4. The LED based on COB substrate according to claim 1, characterized in that: The side walls of the through hole are arranged to be inclined outward from bottom to top.

5. The LED based on COB substrate according to any one of claims 1 to 4, characterized in that: The through hole is punched from top to bottom by using a punching process.

6. A method for preparing an LED having a structure as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: (1) A stamping process is used to stamp a mirror aluminum plate from top to bottom, and a plurality of through holes are stamped out on the mirror aluminum plate to obtain a second mirror aluminum plate; (2) applying pure glue on the lower surface of the second mirror aluminum plate, and bonding the second mirror aluminum plate to the upper surface of the first mirror aluminum plate through the pure glue to obtain a substrate layer; (3) preparing a bonding layer on the substrate layer to obtain a COB substrate; (4) The LED chip is fixed in the concave lamp position by a die-bonding adhesive, and each LED chip and the circuit layer of the bonding layer are electrically connected by bonding wires; then, a dam is prepared on the upper surface of the COB substrate, and the dam is higher than the bonding wire; (5) Fill the cup with fluorescent glue, use a precipitation process to allow the fluorescent powder in the fluorescent glue to gather at a higher concentration on the surface of the substrate layer, and then solidify it into a fluorescent glue layer, thereby producing an LED product.

7. The preparation method according to claim 6, characterized in that: In the step (1), the thickness of the mirror aluminum plate is 0.3 mm, the through hole is in the shape of an inverted truncated cone, and the upper end diameter is mm The lower end diameter is mm; where L, W and H are the length, width and height of the LED chip respectively.

8. The preparation method according to claim 6, characterized in that: The components of the fluorescent glue are LUYAG535 green powder, nitride 630 red powder and low-fold A / B mixed glue.

Images