Laterally-bent COB lamp strip and preparation method thereof

Abstract

The invention provides a laterally-bent COB lamp strip and a preparation method thereof.The preparation method comprises the steps that two rows of solid crystal positions are arranged on the upper surface of a substrate, and intermittent cutting or punching is conducted on the position, located between the two rows of solid crystal positions, of the substrate so that the strength of the position can be low; carrying out die bonding at the die bonding position; two rows of fluorescent glue are poured into the die bonding positions to cover the crystals on the two rows of die bonding positions, and the two rows of fluorescent glue are overlapped; and pasting a double-faced adhesive tape on the lower surface of the substrate, and folding the substrate downwards along the middle of the two rows of crystal fixing positions so as to paste the lower surface of the substrate. Compared with the prior art, the COB lamp strip has the advantages that the plane structure of the COB is changed into the space structure through folding, positive bending and lateral bending can be achieved, positive bending and lateral bending can be achieved, the technology is simple, the light emitting effect is ideal, and the application scene of the lamp strip is greatly expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of decorative lighting, and particularly to a side-bending COB light strip and a preparation method thereof. Background Art

[0002] Applying a COB light strip (Chip On Board Light means chip-on-board packaging technology, that is, a light-emitting body in which multiple LED chips are integrally packaged on the same substrate) to a light strip to form a lighting device suitable for commercial lighting and beautiful lighting atmosphere is a current application trend.

[0003] For a COB light strip, bending up and down with the light-emitting surface as the reference is called positive bending, while bending left and right with the side of the light-emitting surface as the reference is side bending. Conventional COB light strips do not have the side-bending function and can only be positively bent. If forced to be side-bent, the FPC (Flexible Printed Circuit) substrate will be torn. Existing products with the side-bending function have high costs, complex processes, and the product form and light-emitting effect are not very ideal, with asymmetric light emission. Summary of the Invention

[0004] The purpose of the present invention is to provide a side-bending COB light strip and a preparation method thereof, which are used to solve the problems that existing COB light strips do not have the side-bending function or have high side-bending costs, complex processes, and asymmetric light emission.

[0005] On the one hand, the present invention provides a preparation method for a side-bending COB light strip, including: Providing two rows of die-bonding positions on the upper surface of the substrate, and intermittently cutting or punching holes at the middle position between the two rows of die-bonding positions on the substrate to make the strength at this position low; Die-bonding at the die-bonding positions; Pouring two rows of fluorescent glue at the die-bonding positions to cover the crystals on the two rows of die-bonding positions, and the two rows of fluorescent glue overlap; Sticking a double-sided adhesive on the lower surface of the substrate, and folding the substrate downward along the middle position between the two rows of die-bonding positions to paste the lower surface of the substrate.

[0006] The step of providing two rows of die-bonding positions on the upper surface of the substrate, and intermittently cutting or punching holes at the middle position between the two rows of die-bonding positions on the substrate to make the strength at this position low includes: Respectively arranging the two rows of die-bonding positions parallel to the symmetry axis of the substrate and distributing them on both sides of the symmetry axis of the substrate; Intermittently cutting or punching holes along the symmetry axis of the substrate.

[0007] The step of die-bonding at the die-bonding positions includes: Coating conductive glue at the die-bonding positions in a screen printing manner; Using a die bonder to pick and place flip chips at the die-bonding positions; Bake at 170 - 180 °C for 1 - 1.5 hours.

[0008] Pour two rows of fluorescent glue at the die bonding position to cover the crystals on the two rows of die bonding positions, and the two rows of fluorescent glue overlap, including: Pour two rows of fluorescent glue at the die bonding position to excite white light from blue light through the fluorescent glue, so that the thickness range of the overlapping part of the two rows of fluorescent glue is 0.8 - 1.2 mm; Bake for 0.5 - 1 hour; Cool for 1 - 1.2 hours to dry the glue.

[0009] Stick double-sided tape on the lower surface of the substrate, and fold the substrate downward along the middle of the two rows of die bonding positions to paste the lower surface of the substrate, including: Set the two rows of die bonding positions symmetrically about the axis of symmetry of the substrate; Fold the lower surface of the substrate along the axis of symmetry so that the double-sided tape is completely pasted.

[0010] On the one hand, provide a side-bending COB light strip, prepared by the preparation method of the side-bending COB light strip as described above, the side-bending COB light strip includes: A substrate, with two rows of die bonding positions arranged on the upper surface, double-sided tape pasted on the lower surface, and intermittently cut or punched at the middle of the two rows of die bonding positions on the substrate to make the strength at this position low; Crystals, arranged at the die bonding positions; Two rows of fluorescent glue for covering the crystals on the two rows of die bonding positions, and the two rows of fluorescent glue overlap.

[0011] The two rows of die bonding positions are respectively parallel to the axis of symmetry of the substrate and are distributed on both sides of the axis of symmetry of the substrate; the position of intermittent cutting or punching is on the axis of symmetry of the substrate.

[0012] The crystal includes conductive glue and a flip chip, and the flip chip is electrically connected to the conductive glue.

[0013] The thickness range of the overlapping part of the two rows of fluorescent glue is 0.8 - 1.2 mm.

[0014] The two rows of die bonding positions are symmetrically arranged about the axis of symmetry of the substrate, and the lower surface of the substrate is set to be folded along the axis of symmetry so that the double-sided tape is completely pasted.

[0015] As described above, a side-bending COB light strip and its preparation method of the present invention have the following beneficial effects: By folding, the planar structure of the COB is changed into a spatial structure, which can realize both positive bending and side bending, with simple process and ideal light output effect, greatly expanding the application scenarios of the light strip. Brief Description of the Drawings

[0016] Figure 1A structural schematic diagram of a bent COB light strip before folding according to an embodiment of the present invention; Figure 2 A structural schematic diagram of a substrate according to an embodiment of the present invention; Figure 3 A structural schematic diagram of a bent COB light strip after folding according to an embodiment of the present invention. Detailed implementation manners

[0017] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0018] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be an arbitrary change, and the component layout type may also be more complex.

[0019] It should be known that the structures, ratios, sizes, etc. shown in the diagrams of this specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not used to limit the limiting conditions under which the present invention can be implemented. Therefore, they do not have a technical essence. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope that can be covered by the technical content disclosed in the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of clear narration, and are not used to limit the scope under which the present invention can be implemented. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope within which the present invention can be implemented.

[0020] As Figures 1 - 3 shown, Figure 1 A structural schematic diagram of a bent COB light strip before folding according to an embodiment of the present invention, Figure 2 A structural schematic diagram of substrate 1 according to an embodiment of the present invention, Figure 3 A structural schematic diagram of a bent COB light strip after folding according to an embodiment of the present invention. The preparation method of the bent COB light strip includes steps S1 - S4: S1. Set two rows of die bonding positions on the upper surface of the substrate 1, and intermittently cut or punch holes in the middle of the two rows of die bonding positions on the substrate 1 to make the strength at this place low; Step S1 includes steps S11 - S12: S11. Respectively set the two rows of die bonding positions parallel to the symmetry axis 10 of the substrate 1, and distribute them on both sides of the symmetry axis 10 of the substrate 1.

[0021] In this embodiment, referring to Figure 2 , the symmetry axis 10 of the substrate 1 is located in the middle of the two rows of die bonding positions, and the substrate 1 is preferably made of FPC material.

[0022] S12. Intermittently cut or punch holes along the symmetry axis 10 of the substrate 1.

[0023] In this embodiment, by intermittently cutting or punching holes at the symmetry axis 10, that is, drawing dotted lines or dots along the symmetry axis 10 and opening holes at the dotted lines or dots, the strength at the symmetry axis 10 of the substrate 1 can be made lower. Therefore, when folding, it can be folded along the symmetry axis 10.

[0024] S2. Bond dies at the die bonding positions; Step S2 includes steps S21 - S23: S21. Coat conductive adhesive at the die bonding positions by screen printing.

[0025] In this embodiment, coating conductive adhesive by screen printing is a method of uniformly coating conductive adhesive on a substrate through screen printing technology. The specific steps include S211 - S215: S211. First, select a suitable conductive adhesive paste to ensure its good conductivity and adhesiveness. Conductive adhesive is usually composed of conductive particles (such as silver powder) and a binder.

[0026] S212. Make a screen plate with the required pattern. The screen plate is usually made of stainless steel or nylon, coated with photosensitive glue on the surface, and the required pattern is formed through exposure and development.

[0027] S213. Place the conductive adhesive under the screen plate, and use a squeegee or a similar tool to evenly scrape the conductive adhesive across the screen plate, so that the conductive adhesive is transferred to the substrate through the opening part of the screen. This process requires controlling the pressure of the squeegee and the printing speed to ensure the uniformity and consistency of the coating.

[0028] S214. After coating, the conductive adhesive needs to be dried and cured. This usually includes low - temperature drying to remove the solvent, and then heat treatment to complete the curing.

[0029] S215. Finally, conduct quality inspection on the coated conductive adhesive to ensure that its conductivity and adhesiveness meet the requirements. Repair or re - coat if necessary.

[0030] S22. Use a die bonder to pick and place flip chips at the die bonding position.

[0031] In this embodiment, in the COB die bonding process, the chip picking and placing steps of the die bonder are the core links, which directly affect the chip positioning accuracy and yield. The steps of using a die bonder to pick and place chips at the die bonding position include S221 - S225: S221. Fix the pre - processed substrate 1 (PCB or ceramic substrate 1) on the die bonder workbench through vacuum adsorption or fixture, ensuring it is flat and without warping; paste the diced wafer (chip array) on the UV film, and irradiate the film with UV light to expand the film and increase the chip pitch for easy pick - up by the robotic arm.

[0032] S222. Select ceramic or carbon fiber nozzles (anti - static and wear - resistant) for the nozzle material, and the diameter needs to match the chip size (e.g., <100μm nozzles for MiniLED chips). Through vacuum adsorption, adjust the vacuum pressure (usually 50 - 150 kPa) to avoid excessive suction force causing chip cracks; identify the chip positions on the wafer through a high - resolution camera (5μm accuracy), automatically avoiding the dicing channels or defective chips; adjust the nozzle height according to the chip thickness (e.g., 150μm for LED chips) to prevent collision with the wafer. The vacuum pressure range of the nozzle is 50 - 150 kPa, and the adjustment principle is that the smaller the chip size, the lower the pressure.

[0033] S223. The robotic arm moves at high speed (1 - 3 m / s), with an X / Y axis accuracy of ±3μm, and fine - tunes the Z axis to avoid impact; the rotation axis (θ axis) corrects the chip angle offset (e.g., within ±1°); simultaneously identify the alignment marks (Fiducial Mark) on the substrate 1 and the chip electrode positions through a dual - camera system; adjust the coordinates in real time according to the thermal expansion or deformation of the substrate 1 to ensure the alignment accuracy (within ±5μm).

[0034] S224. Control the chip placement through contact; the nozzle decelerates before contacting the substrate 1 and applies a light pressure (0.1 - 0.5 N) after contact to prevent chip fragmentation; the chip needs to be placed within 5 seconds after dispensing to ensure uniform diffusion of the colloid (the glue layer thickness is 5 - 15μm); after turning off the vacuum, detect the rebound height of the nozzle through a force sensor to confirm that the chip is completely detached from the nozzle; a high - sensitivity sensor monitors the placement process, and if abnormal resistance (such as glue adhesion) is detected, trigger an alarm and record the position.

[0035] S225. Immediately take a picture of the chip position after placement to detect offset, tilt, or glue overflow (e.g., if the glue covers the electrode >10%, it is judged as NG); classify the defect types (such as offset, lack of glue, flipping) through machine learning algorithms and feedback to the die bonder to adjust the parameters; record the pressure curve of each placement, and if abnormal fluctuations (such as chip fragmentation signals) occur, automatically stop the machine for troubleshooting.

[0036] S23. Bake at 170 - 180 °C for 1 - 1.5 hours.

[0037] In this embodiment, take the encapsulation substrate 1, apply die bonding glue dropwise in the die bonding grooves of the encapsulation substrate 1, bond the COB chips in the die bonding grooves respectively, perform ultrasonic treatment for 3 min, let it stand for 5 min, then transfer it to an oven and preferably bake for 1.5 h, the baking temperature is preferably 170 °C, and it is under ultrasonic conditions during baking, the ultrasonic power is 60 W, and the ultrasonic frequency is 20 kHz.

[0038] S3. Pour two rows of fluorescent glue 3 at the die bonding position to cover the crystals 2 on two rows of die bonding positions, and the two rows of fluorescent glue 3 overlap; Step S3 includes steps S31 - S33: S31. Pour two rows of fluorescent glue 3 at the die bonding position to excite white light from blue light through the fluorescent glue 3, so that the thickness range of the overlapping part of the two rows of fluorescent glue 3 is 0.8 - 1.2 mm.

[0039] In this embodiment, the overlapping part of the two rows of fluorescent glue 3 is located around the symmetry axis 10 of the substrate 1, see Figures 1 - 3 , the overlapping part of the two rows of fluorescent glue 3 wraps the upper surface of the symmetry axis 10 of the substrate 1. When folded downwards, the overlapping part becomes the side of the light strip. Therefore, one side of the bent COB light strip in this case can also emit light.

[0040] S32. Bake for 0.5 - 1 hour.

[0041] In this embodiment, it is under ultrasonic conditions during baking, the ultrasonic power is 60 W, and the ultrasonic frequency is 20 kHz. Preferably bake at 150 °C for 50 minutes.

[0042] S33. Cool for 1 - 1.2 hours to dry the glue.

[0043] In this embodiment, cool down at a rate of 2 °C / min.

[0044] S4. Stick double - sided tape on the lower surface of the substrate 1, fold the substrate 1 downwards along the middle of the two rows of die bonding positions to paste the lower surface of the substrate 1. Step S4 includes steps S41 - S42: S41. Arrange the two rows of die bonding positions symmetrically with respect to the symmetry axis 10 of the substrate 1.

[0045] In this embodiment, the two rows of die bonding positions are arranged symmetrically with respect to the symmetry axis 10 of the substrate 1, which can make the upper and lower surfaces emit light evenly after folding.

[0046] S42. Fold the lower surface of the substrate 1 along the symmetry axis 10 so that the double - sided tape is completely pasted.

[0047] In this embodiment, the symmetry axis 10 divides the lower surface of the substrate 1 into two equal halves. Folding the lower surface of the substrate 1 along the symmetry axis 10 can make the double-sided tape stick completely, and the lower surface is completely in a sticking state. Thus, in this case, the folding technique is utilized to change the planar structure of the COB into a spatial structure. Without folding, it is a normal COB light strip with a large luminous surface. When it is folded, it forms a bent COB light strip. It can also achieve partial positive bending and partial side bending, being able to bend both positively and sidewise, forming a 3D COB light strip, which greatly expands the application scenarios of the light strip.

[0048] Refer to Figures 1 - 3 , a side-bent COB light strip provided in this case is prepared by the preparation method of the side-bent COB light strip in this case. The side-bent COB light strip includes a substrate 1, crystals 2, and two rows of fluorescent glue 3.

[0049] On the upper surface of the substrate 1, two rows of die bonding positions are provided. On the lower surface, a double-sided tape is pasted. In the middle of the two rows of die bonding positions on the substrate 1, it is intermittently cut or punched to make the strength at this place low. The crystals 2 are arranged at the die bonding positions. The two rows of die bonding positions are respectively parallel to the symmetry axis 10 of the substrate 1 and are distributed on both sides of the symmetry axis 10 of the substrate 1; the position of the intermittent cutting or punching is on the symmetry axis 10 of the substrate 1.

[0050] In this embodiment, the symmetry axis 10 of the substrate 1 is located in the middle of the two rows of die bonding positions. The substrate 1 is preferably made of FPC material. By intermittently cutting or punching at the symmetry axis 10, that is, drawing a dotted line or dots along the symmetry axis 10 and opening at the dotted line or dots, the strength at the symmetry axis 10 of the substrate 1 can be made lower. Therefore, when folding, it can be folded along the symmetry axis 10.

[0051] The two rows of fluorescent glue 3 are used to cover the crystals 2 on the two rows of die bonding positions, and the two rows of fluorescent glue 3 overlap. The thickness range of the overlapping part of the two rows of fluorescent glue 3 is 0.8 - 1.2 mm.

[0052] In this embodiment, the overlapping part of the two rows of fluorescent glue 3 is located around the symmetry axis 10 of the substrate 1. Refer to Figures 1 - 3 , the overlapping part of the two rows of fluorescent glue 3 wraps the upper surface of the symmetry axis 10 of the substrate 1. When folding downwards, the overlapping part becomes the side of the light strip. Therefore, one side of the side-bent COB light strip in this case can also emit light.

[0053] The crystal 2 includes conductive glue and a flip chip, and the flip chip is electrically connected to the conductive glue.

[0054] In this embodiment, solder mask production and drilling are performed on the upper surface of the substrate 1 to form a packaged substrate 1. Take the packaged substrate 1, apply die bonding glue in the die bonding grooves of the packaged substrate 1, and respectively bond the COB chips in the die bonding grooves; adopt the thermocompression ultrasonic bonding process to connect and bond the COB chips to the circuit on the surface of the packaged substrate 1 through gold wires.

[0055] The two rows of die bonding positions are symmetrically arranged with respect to the symmetry axis 10 of the substrate 1, and the lower surface of the substrate 1 is arranged to be folded along the symmetry axis 10 so that the double-sided tape is completely adhered.

[0056] In this embodiment, the two rows of die bonding positions are symmetrically arranged with respect to the symmetry axis 10 of the substrate 1, and after folding, the light emission on the upper and lower surfaces can be made uniform. The symmetry axis 10 divides the lower surface of the substrate 1 into two equal halves. Folding the lower surface of the substrate 1 along the symmetry axis 10 can make the double-sided tape completely adhered, and the lower surface is completely in the adhered state. In this way, this case utilizes the folding technique to change the planar structure of the COB into a spatial structure. Without folding, it is a normal COB light strip with a large light-emitting surface. When it is folded, it forms a laterally bent COB light strip, and it can also achieve partial forward bending and partial lateral bending. It can be both forward bent and laterally bent to form a 3D COB light strip, greatly expanding the application scenarios of the light strip.

[0057] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A preparation method of a side-curved COB light strip, characterized in that, Including: Two rows of die bonding positions are arranged on the upper surface of the substrate, and intermittent cutting or punching is performed on the substrate and at the middle position between the two rows of die bonding positions to make the strength at this position low; Die bonding is performed at the die bonding positions; Two rows of fluorescent glue are poured at the die bonding positions to cover the crystals on the two rows of die bonding positions, and the two rows of fluorescent glue overlap; Double-sided tape is pasted on the lower surface of the substrate, and the substrate is folded downward along the middle position between the two rows of die bonding positions to paste the lower surface of the substrate.

2. The preparation method according to claim 1, characterized in that, The step of arranging two rows of die bonding positions on the upper surface of the substrate and performing intermittent cutting or punching on the substrate and at the middle position between the two rows of die bonding positions to make the strength at this position low includes: The two rows of die bonding positions are respectively arranged parallel to the symmetry axis of the substrate and are distributed on both sides of the symmetry axis of the substrate; Intermittent cutting or punching is performed along the symmetry axis of the substrate.

3. The preparation method according to claim 1, characterized in that, The step of die bonding at the die bonding positions includes: Applying conductive glue at the die bonding positions by screen printing; Using a die bonder to pick and place flip chips at the die bonding positions; Baking at 170 - 180 °C for 1 - 1.5 hours.

4. The preparation method according to claim 1, characterized in that, The step of pouring two rows of fluorescent glue at the die bonding positions to cover the crystals on the two rows of die bonding positions and the two rows of fluorescent glue overlapping includes: Pouring two rows of fluorescent glue at the die bonding positions to excite white light from blue light through the fluorescent glue, and the thickness range of the overlapping part of the two rows of fluorescent glue is 0.8 - 1.2 mm; Baking for 0.5 - 1 hour; Cooling for 1 - 1.2 hours to dry the glue.

5. The preparation method according to claim 1, characterized in that, The step of pasting double-sided tape on the lower surface of the substrate and folding the substrate downward along the middle position between the two rows of die bonding positions to paste the lower surface of the substrate includes: The two rows of die bonding positions are symmetrically arranged with respect to the symmetry axis of the substrate; Folding the lower surface of the substrate along the symmetry axis so that the double-sided tape is completely pasted.

6. A side-curved COB light strip, prepared by the preparation method of the side-curved COB light strip according to any one of claims 1-5, characterized in that, The described side-bending COB light strip includes: A substrate, with two rows of die bonding positions arranged on the upper surface, double-sided tape pasted on the lower surface, and intermittent cutting or punching is performed on the substrate and at the middle position between the two rows of die bonding positions to make the strength at this position low; Crystals, arranged at the die bonding positions; Two rows of fluorescent glue for covering the crystals on the two rows of die bonding positions, and the two rows of fluorescent glue overlap.

7. The side-bending COB light strip according to claim 6, wherein The two rows of die bonding positions are respectively parallel to the symmetry axis of the substrate and are distributed on both sides of the symmetry axis of the substrate; the position of intermittent cutting or punching is on the symmetry axis of the substrate.

8. The side-bending COB light strip according to claim 6, wherein, The crystals include conductive glue and flip chips, and the flip chips are electrically connected to the conductive glue.

9. The side-curved COB light strip according to claim 6, characterized in that, The thickness range of the overlapping part of the two rows of fluorescent glue is 0.8 - 1.2 mm.

10. The side-bending COB light strip according to claim 6, characterized in that, The two rows of die bonding positions are symmetrically arranged with respect to the symmetry axis of the substrate, and the lower surface of the substrate is arranged to be folded along the symmetry axis so that the double-sided tape is completely pasted.

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