CN113909155B - Cutting detection method of LED circuit board and LED circuit board structure - Google Patents
Cutting detection method of LED circuit board and LED circuit board structure Download PDFInfo
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- CN113909155B CN113909155B CN202111165305.4A CN202111165305A CN113909155B CN 113909155 B CN113909155 B CN 113909155B CN 202111165305 A CN202111165305 A CN 202111165305A CN 113909155 B CN113909155 B CN 113909155B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
- B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
- B07C5/34—Sorting according to other particular properties
- B07C5/342—Sorting according to other particular properties according to optical properties, e.g. colour
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
- G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
- G09F9/33—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements being semiconductor devices, e.g. diodes
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0266—Marks, test patterns or identification means
- H05K1/0269—Marks, test patterns or identification means for visual or optical inspection
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
- B07C2301/00—Sorting according to destination
- B07C2301/0008—Electronic Devices, e.g. keyboard, displays
Abstract
The application discloses a cutting detection method of LED circuit board and LED circuit board structure relates to LED technical field, and it includes: covering the LED circuit board with ink once, covering the metal via holes and the metal wires of the LED circuit board, and not covering the bonding pads; primary ink on the front surface of each adjacent full-color LED display structure is not connected, and in each single full-color LED display structure, the distance from the edge of the primary ink on the front surface to the edge of the full-color LED display structure is larger than a preset distance; covering the front surface of the LED circuit board covered by the primary ink by using secondary ink which is fluorescent ink, so as to cover the area between the edges of two adjacent primary inks on the front surface; and cutting the LED circuit board to obtain a plurality of full-color LED display units, respectively carrying out fluorescence detection on four sides of each full-color LED display unit, wherein all the full-color LED display units with fluorescence reaction on the sides are qualified products for cutting. The application can realize the screening to the defective products, reduces the outflow of defective products.
Description
Technical Field
The application relates to the technical field of LEDs, in particular to a cutting detection method of an LED circuit board and an LED circuit board structure.
Background
At present, in the all-in-one full-color display structure, as the distance between the circuit structure and the edge is small, the welding disc of the functional area is too close to the cutting area of the edge, and the tolerance of the existing cutting process is larger than that of the reserved position, the functional area is easily damaged, and the overall reliability of the product is influenced; in addition, the product overall dimension is little, when the product cuts, appears drawing the off tracking condition easily, and because the design of small size and original structure leads to being unfavorable for manual work or equipment inspection, is difficult to get rid of bad product, consequently, can have a lot of bad products to flow, reduces product overall yield and performance.
Disclosure of Invention
Aiming at one of the defects existing in the prior art, the purpose of the application is to provide a cutting detection method of an LED circuit board and an LED circuit board structure, so as to solve the problems that poor products are difficult to eliminate in the related art, and the overall yield and performance of the products are low.
The first aspect of the present application provides a method for detecting cutting of an LED circuit board, where the LED circuit board is formed by arranging a plurality of full-color LED display units in an array, and the method includes the steps of:
covering the LED circuit board with ink once, covering the metal via holes and the metal wires of the LED circuit board, and not covering the bonding pads; primary ink on the front surface of each adjacent full-color LED display structure is not connected, and in each single full-color LED display structure, the distance from the edge of the primary ink on the front surface to the edge of the full-color LED display structure is larger than a preset distance;
covering the front surface of the LED circuit board covered by the primary ink by using secondary ink which is fluorescent ink, so as to cover the area between the edges of two adjacent primary inks on the front surface;
and cutting the LED circuit board to obtain a plurality of full-color LED display units, respectively carrying out fluorescence detection on four sides of each full-color LED display unit, wherein all the full-color LED display units with fluorescence reactions on the sides are qualified products for cutting.
In some embodiments, the LED circuit board is covered with ink once, which specifically includes:
coating solder resist ink on the LED circuit board;
after the solder mask is covered on the solder mask ink of the LED circuit board, exposure treatment is carried out; the solder mask comprises a plurality of groups of contour windowing lines, and each group of contour windowing lines corresponds to the contour of the shape of primary ink to be molded on a full-color LED display unit;
and developing the exposed LED circuit board to remove the solder resist ink corresponding to the area outside the profile window line, wherein the rest solder resist ink forms primary ink.
In some embodiments, the secondary ink is a fluorescent ink that is excited only by invisible light.
In some embodiments, fluorescence detection is performed on four sides of each full-color LED display unit, which specifically includes:
the four sides of each full-color LED display unit are sequentially irradiated by adopting a light source of invisible light, and whether fluorescence reaction exists or not is identified by using CCD lenses respectively.
In some embodiments, the invisible light is ultraviolet light or infrared light.
In some embodiments, before the LED circuit board performs one ink coverage, the method further includes:
and acid washing, primary washing, plate grinding, secondary washing and drying are sequentially carried out on the LED circuit board.
In some embodiments, the secondary water washing step includes ultrasonic water washing and clear water rinsing.
A second aspect of the present application provides an LED circuit board structure, comprising:
the LED circuit board is formed by arranging a plurality of full-color LED display units in an array manner;
the first ink layer is used for covering the metal via holes and the metal wires of the LED circuit board and does not cover the bonding pads; the first ink layers on the front surfaces of the adjacent full-color LED display structures are not connected, and in the single full-color LED display structure, the distance from the edge of the first ink layer on the front surface to the edge of the full-color LED display structure is larger than a preset distance;
and the second ink layer is used for covering the area between the edges of two adjacent first ink layers, and the second ink layer adopts fluorescent ink.
In some embodiments, the full-color LED display unit includes an upper circuit board and a lower circuit board, where the upper circuit board and the lower circuit board are connected through metal vias.
In some embodiments, the upper circuit board is divided into four areas by a cross, and the upper circuit board is provided with:
two die bond pad assemblies;
four pixel units, two of which are arranged on one die bonding pad assembly, wherein the four pixel units are respectively positioned in each area of the upper circuit board; each pixel unit comprises three light emitting chips, the three light emitting chips are all positioned on the same straight line, and the three light emitting chips in different pixel units are arranged in a translational symmetry mode;
the B electrode bonding pads are arranged in one-to-one correspondence with each light emitting chip and are respectively connected with the B electrodes of the corresponding light emitting chips, and the A electrodes of each light emitting chip are respectively connected with the die bonding pad assembly where the A electrodes of the light emitting chips are positioned; the polarity of the A pole is opposite to that of the B pole.
The beneficial effects that technical scheme that this application provided brought include:
according to the cutting detection method of the LED circuit board and the LED circuit board structure, the primary ink coverage and the secondary ink coverage are sequentially carried out on the LED circuit board, so that the distance from the primary ink edge of the front face to the edge of the full-color LED display structure in a single full-color LED display structure is larger than a preset distance, the secondary ink is fluorescent ink and covers the area between two adjacent primary ink edges of the front face, then the LED circuit board can be cut to obtain a plurality of full-color LED display units, fluorescent detection is carried out on four sides of each full-color LED display unit respectively, and full-color LED display units with fluorescent reactions on all sides are used as qualified products for cutting; the invention effectively realizes the screening of defective products, reduces the outflow of the defective products, and increases the overall yield and performance of the product.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic front view of a full-color LED display unit in step S1 in the embodiment of the present application;
fig. 2 is a schematic back view of a full-color LED display unit in step S1 in the embodiment of the present application;
fig. 3 is a schematic front view of a full-color LED display unit in step S2 in the embodiment of the present application;
fig. 4 is a schematic structural diagram of an upper layer circuit board in the embodiment of the present application;
fig. 5 is a schematic structural diagram of a lower circuit board in an embodiment of the present application.
Reference numerals:
1. an upper layer circuit board; 2. a die bond pad assembly; 3. a die bond pad; 4. a connection section; 5. a first pixel unit; 6. a second pixel unit; 7. a third pixel unit; 8. a fourth pixel unit; 9. a common a-pole pad; 10. a second extension; 11. a blue light chip; 12. a green light chip; 13. a red light chip; 14. a lower layer circuit board; 15. a first blue light B-pole bonding pad; 16. a second blue light B pole bonding pad; 17. a third blue light B electrode bonding pad; 18. a fourth blue light B-pole pad; 19. a first green B-pole pad; 20. a second green B-electrode pad; 21. a third green B-electrode pad; 22. a fourth green B-pole pad; 23. a first red B-pole pad; 24. a second red B-electrode pad; 25. a third red B-electrode bonding pad; 26. a fourth red B-pole pad; 27. a first lower layer pad; 28. a second lower layer pad; 29. a third lower layer pad; 30. a fourth lower layer pad; 31. a fifth lower layer pad; 32. a sixth lower layer pad; 33. a seventh lower layer pad; 34. an eighth lower layer pad;
101. primary ink; 102. and (5) secondary ink.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present invention will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
The embodiment of the application provides a cutting detection method of an LED circuit board, which can solve the problem that poor products are difficult to eliminate in related technologies, so that the overall yield and performance of the products are low.
The LED circuit board is formed by arranging a plurality of full-color LED display unit arrays, and the cutting detection method of the LED circuit board comprises the following steps of:
s1, performing primary ink covering on an LED circuit board to cover metal through holes and metal wires of the LED circuit board and not cover bonding pads; the primary ink 101 on the front surface of the adjacent full-color LED display structure is not connected, and in the single full-color LED display structure, the distance from the edge of the primary ink 101 on the front surface to the edge of the full-color LED display structure is greater than the preset distance.
Optionally, the preset distance may be set according to actual process conditions, so as to avoid that the tolerance of the primary ink 101 covering process causes the primary ink 101 to cover the functional area such as the pad. In this embodiment, the predetermined distance is 65um.
S2, performing secondary ink covering on the front surface of the LED circuit board covered by the primary ink so as to cover the area between the edges of two adjacent primary inks 101 on the front surface, wherein the secondary ink 102 is fluorescent ink. The front face of the LED circuit board is the front face of the full-color LED display structure.
S3, cutting the LED circuit board covered by the printing ink to obtain a plurality of full-color LED display units covered by the printing ink, respectively carrying out fluorescence detection on four sides of each full-color LED display unit, wherein all full-color LED display units with fluorescence reactions on all sides are qualified products for cutting, and all full-color LED display units without fluorescence reactions on any side are poor products for cutting.
According to the cutting detection method, primary ink coverage and secondary ink coverage are sequentially carried out on the LED circuit board, so that the distance from the primary ink edge of the front face to the edge of the full-color LED display structure in a single full-color LED display structure is larger than a preset distance, the secondary ink is fluorescent ink and covers the area between two adjacent primary ink edges of the front face, then the LED circuit board can be cut to obtain a plurality of full-color LED display units, fluorescence detection is carried out on four sides of each full-color LED display unit respectively, and full-color LED display units with fluorescence reaction on all sides are taken as cut qualified products; the method effectively realizes the screening of defective products, reduces the outflow of the defective products, and increases the overall yield and performance of the product.
As shown in fig. 1 and 2, in this embodiment, the step S1 of performing the ink covering on the LED circuit board once specifically includes the following steps:
firstly, coating solder resist ink on the LED circuit board; the solder resist ink is printed on all places of the LED circuit board in the front surface by using solder resist ink equipment, and the whole LED circuit board is covered by the ink. The LED circuit board warping degree can be reduced, and meanwhile, the circuit can be prevented from leaking.
Then, after the solder mask film is covered on the solder mask ink of the LED circuit board, exposure treatment is carried out; the solder mask comprises a plurality of groups of contour windowing lines, and each group of contour windowing lines corresponds to the contour of the primary ink shape to be molded on one full-color LED display unit. In this embodiment, the primary ink shapes of the front and back surfaces of the LED wiring board are different.
Finally, the exposed LED circuit board is developed to remove the solder resist ink corresponding to the area outside the window lines of each group of profiles, and the rest of solder resist ink forms primary ink 101. In this embodiment, the coverage of the primary ink can be controlled at all pad edges.
Preferably, the full-color LED display unit is an RGB full-color lamp bead, and the RGB three colors can mix various different colors of light, so that in order to avoid the effect of using visible wave bands to influence the normal use of the product, the fluorescent ink is a fluorescent ink excited by only invisible light, so as to realize the photoluminescence cold light emission phenomenon.
Optionally, the invisible light is ultraviolet light or infrared light.
In this embodiment, the fluorescent ink is an UV (ultraviolet) fluorescent ink, so as to meet the use requirement of exposure and development.
In the embodiment, as shown in fig. 3, the front surface of the LED circuit board covered with the primary ink in the step S2 is covered with the secondary ink, and the covering principle is that the outline window line on the solder mask corresponds to the outline of the secondary ink to be formed on the front surface of the LED circuit board.
In this embodiment, after the secondary ink coverage, the front-to-back ink coverage ratio of each full-color LED display unit may be greater than 60%.
Optionally, after the front surface of the LED circuit board is covered with the secondary ink, the back surface of the LED circuit board may be covered with the tertiary ink, so as to identify the direction.
Further, in the step S3, fluorescence detection is performed on four sides of each full-color LED display unit, which specifically includes the following steps:
the four sides of each full-color LED display unit are sequentially irradiated by adopting a light source of invisible light, and whether fluorescence reaction exists or not is identified by using a CCD (Charge Coupled Device ) lens respectively.
The full-color LED display unit without abnormality in cutting has fluorescent reaction on four sides, if any side has no fluorescent reaction, the full-color LED display unit is judged to be cut and damaged, namely, when the full-color LED display unit is cut, the function area of the full-color LED display unit is cut, and the full-color LED display unit needs to be removed.
In this embodiment, in the step S1, before the LED circuit board performs the primary ink coverage, the method further includes the following steps:
and acid washing, primary washing, plate grinding, secondary washing and drying are sequentially carried out on the LED circuit board.
Preferably, the secondary water washing step includes ultrasonic water washing, clear water rinsing, and the like.
In this embodiment, since the surface of the circuit copper on the LED circuit board is oxidized to a certain extent after the circuit copper is exposed, an acid washing step is required to remove the impurities such as oxidation and oil stains. The ink can be better combined with the LED circuit board through a plate grinding step.
The embodiment of the application also provides an LED circuit board structure, which comprises an LED circuit board, a first ink layer and a second ink layer.
The LED circuit board is formed by arranging a plurality of full-color LED display units in an array mode.
The first ink layer is used for covering the metal via hole and the metal wire of the LED circuit board and not covering the bonding pad; the first ink layers on the front surfaces of the adjacent full-color LED display structures are not connected, and in the single full-color LED display structure, the distance from the edge of the first ink layer on the front surface to the edge of the full-color LED display structure is larger than a preset distance.
And the second ink layer is used for covering the area between the edges of two adjacent first ink layers, and fluorescent ink is adopted for the second ink layer.
After the LED circuit board structure of this embodiment is cut, a plurality of full-color LED display units covered with the first ink layer and the second ink layer can be obtained, that is, the full-color LED display units are covered with the primary ink and the secondary ink, and by respectively performing fluorescence detection on four sides of each full-color LED display unit, all the full-color LED display units with fluorescence reactions on all the sides are cut qualified products, and all the full-color LED display units without fluorescence reactions on any sides are cut defective products.
As shown in fig. 4 and 5, in the embodiment, the full-color LED display unit includes an upper circuit board 1 on the front side and a lower circuit board 14 on the back side, a plurality of metal vias are correspondingly formed between the upper circuit board 1 and the lower circuit board 14, and the upper circuit board 1 and the lower circuit board 14 are connected through the metal vias.
Further, the upper layer circuit board 1 is equally divided into four areas by a cross, and two die bonding pad assemblies 2, four pixel units and a plurality of B-pole pads are arranged on the upper layer circuit board.
Two pixel units are arranged on one die bonding pad assembly 2, and four pixel units are respectively positioned in each area of the upper circuit board 1; each pixel unit comprises three light emitting chips, the three light emitting chips are all positioned on the same straight line, and the three light emitting chips in different pixel units are arranged in a translational symmetry mode.
The plurality of B electrode bonding pads are respectively arranged in one-to-one correspondence with each light emitting chip, the plurality of B electrode bonding pads are respectively connected with the B electrodes of the corresponding light emitting chips, and the A electrodes of each light emitting chip are respectively connected with the die bonding pad assembly 2 where the A electrodes are positioned; the polarity of the A pole is opposite to that of the B pole.
Further, each of the above die bond pad assemblies 2 includes two die bond pads 3, two common a-pole pads 9, and one connection section 4.
Each die bonding pad 3 is provided with a pixel unit.
Each common a-pole pad 9 is an L-shaped pad formed by extending the right side of one die bond pad 3, and each common a-pole pad is connected to the a-pole of an adjacent pixel cell. The A poles of the three light emitting chips of each pixel unit are electrically connected with adjacent common A pole bonding pads, so that the common ends of two pixel units in the same row are connected together.
Wherein, the L-shaped bonding pad comprises a first extension part formed by extending the right side of the die bonding pad 3 and a second extension part 10 extending from the tail end of the first extension part; the extending directions of the four second extending portions 10 are the same.
The connecting section 4 is used for connecting two die bonding pads 3, and the connecting section 4 is arranged close to the edge of the upper circuit board 1.
In the present embodiment, in the four regions, the first pixel unit 5 and the second pixel unit 6 are respectively arranged in the upper row from left to right, and the third pixel unit 7 and the fourth pixel unit 8 are respectively arranged in the lower row from left to right.
One end of the connection section 4 between the first pixel unit 5 and the second pixel unit 6 is connected with a common a-pole pad 9 formed by extending the die bonding pad 3 where the first pixel unit 5 is located, and the other end of the connection section 4 is connected with the die bonding pad 3 where the second pixel unit 6 is located.
Two ends of the connecting section 4 between the third pixel unit 7 and the fourth pixel unit 8 are respectively connected with two die bonding pads 3, namely, the die bonding pads 3 where the third pixel unit 7 and the fourth pixel unit 8 are respectively connected.
Specifically, when the common a-electrode pad 9 is a common negative electrode pad, the B-electrode pad is a positive electrode pad; when the common a-electrode pad 9 is a common positive electrode pad, the B-electrode pad is a negative electrode pad.
Based on the above embodiments, in this embodiment, the three light emitting chips in each pixel unit are, from top to bottom, a blue light chip 11, a green light chip 12 and a red light chip 13 in order, where the blue light chip 11 and the green light chip 12 are in a horizontal structure, and the red light chip 13 is in a vertical structure.
Further, the a pole of the red light chip 13 is fixedly connected to the corresponding die bonding pad 3 through a conductive material, so that the electrical connection with the common a pole pad 9 is realized, and the manufacturing process is saved. The blue light chip 11 and the green light chip 12 are fixedly connected to the corresponding die bonding pads 3 through insulating materials. The extending directions of the four second extending portions 10 are the same, so that the second extending portions 10 are electrically connected with the adjacent blue light chip 11 and the adjacent green light chip 12.
In this embodiment, the B pole of the red light chip 13, and the a pole and the B pole of the blue light chip 11 and the green light chip 12 are electrically connected to the corresponding pad areas through bonding wires.
In this embodiment, the conductive material is conductive adhesive, and the insulating material is insulating adhesive, so as to increase the connection reliability of the LED display unit.
Alternatively, the lower wiring board 14 includes eight lower pads equally spaced in the circumferential direction, four of which are located at four corners of the lower wiring board 14.
Each pad group is electrically connected to one lower pad, and each connection section 4 is electrically connected to one lower pad, respectively.
In the present embodiment, the eight lower-layer pads are a first lower-layer pad 27, a second lower-layer pad 28, a third lower-layer pad 29, a fourth lower-layer pad 30, a fifth lower-layer pad 31, a sixth lower-layer pad 32, a seventh lower-layer pad 33, and an eighth lower-layer pad 34, respectively.
Further, the plurality of B-pole pads includes a first blue-light pad set, a second blue-light pad set, a first green-light pad set, a second green-light pad set, a first red-light pad set, and a second red-light pad set.
The first blue light bonding pad group comprises a first blue light B-electrode bonding pad 15 corresponding to the blue light chip 11 in the first pixel unit 5 and a third blue light B-electrode bonding pad 17 corresponding to the blue light chip 11 in the third pixel unit 7, the first blue light B-electrode bonding pad 15 and the third blue light B-electrode bonding pad 17 are connected through the wires on the upper circuit board 1, and the first blue light B-electrode bonding pad 15 is also connected to a first lower layer bonding pad 27 through a metal via hole.
The second blue light pad group comprises a second blue light B-pole pad 16 corresponding to the blue light chip 11 in the second pixel unit 6 and a fourth blue light B-pole pad 18 corresponding to the blue light chip 11 in the fourth pixel unit 8, the second blue light B-pole pad 16 and the fourth blue light B-pole pad 18 are connected through the wires on the upper circuit board 1, and the wires are connected to the wires connected with the second lower layer pad 28 through metal vias.
The first green light pad group comprises a first green light B-electrode pad 19 corresponding to the green light chip 12 in the first pixel unit 5 and a third green light B-electrode pad 21 corresponding to the green light chip 12 in the third pixel unit 7, the first green light B-electrode pad 19 and the third green light B-electrode pad 21 are connected through a wire on the upper layer circuit board 1, the wire is positioned between the first red light B-electrode pad 23 and the second blue light B-electrode pad 16, and the wire is connected to the seventh lower layer pad 33 through a metal via hole;
the second green light pad group includes a second green light B-pole pad 20 corresponding to the green light chip 12 in the second pixel unit 6, and a fourth green light B-pole pad 22 corresponding to the green light chip 12 in the fourth pixel unit 8, the second green light B-pole pad 20 and the fourth green light B-pole pad 22 are connected by a wire on the lower layer wiring board 14, one end of the wire is connected to the wire connected to the fourth green light B-pole pad 22 by a metal via hole, the other end is connected to the eighth lower layer pad 34, and the wire connected to the second green light B-pole pad 20 is connected to the eighth lower layer pad 34 by a metal via hole.
The first red light bonding pad group comprises a first red light B-electrode bonding pad 23 corresponding to the red light chip 13 in the first pixel unit 5 and a third red light B-electrode bonding pad 25 corresponding to the red light chip 13 in the third pixel unit 7, the first red light B-electrode bonding pad 23 and the third red light B-electrode bonding pad 25 are connected through a wire on the lower layer circuit board 14, one end of the wire is connected with the first red light B-electrode bonding pad 23 through a metal via hole, the other end of the wire is connected to the third lower layer bonding pad 29, and the third red light B-electrode bonding pad 25 is connected with the third lower layer bonding pad 29 through a metal via hole.
The second red light bonding pad group comprises a second red light B-electrode bonding pad 24 corresponding to the red light chip 13 in the second pixel unit 6 and a fourth red light B-electrode bonding pad 26 corresponding to the red light chip 13 in the fourth pixel unit 8, wherein the second red light B-electrode bonding pad 24 and the fourth red light B-electrode bonding pad 26 are connected through the wires on the lower circuit board 14, one end of each wire is connected with the second red light B-electrode bonding pad 24 through a metal via hole, the other end of each wire is connected to the fourth lower layer bonding pad 30, the fourth red light B-electrode bonding pad 26 is connected with the fourth lower layer bonding pad 30 through a metal via hole, the wires are curved wires, and the wires are connected by bypassing the second green light B-electrode bonding pad 20 so as to meet the requirements of the distances in all directions and are connected to the upper circuit board 1.
In this embodiment, the connection section 4 located above is connected to the fifth lower pad 31 through a metal via, and the connection section 4 located below is connected to the sixth lower pad 32 through a metal via.
According to the full-color LED display unit, based on the improvement of the process precision of the PCB, the distance between the bonding pads can reach the minimum distance of 70um, and further, through carrying out re-optimization design on the whole bonding pad structure, the three light emitting chips in each pixel unit are arranged in a translational symmetry mode, the whole structure is more compact and convenient to wire, the matching state between the upper circuit board and the lower circuit board is effectively increased, the distance from the edge of the bonding pad to the edge of the full-color LED display unit is increased, the distance is not less than 75um, and the probability of scratching is reduced.
The LED circuit board structure is suitable for the cutting detection methods, and can realize rapid and effective cutting detection by utilizing the change of the layout of the full-color LED display unit and the change of the ink structure and the process, thereby increasing the identification efficiency, reducing the outflow of defective products and increasing the overall yield and the performance of products.
In the description of the present application, it should be noted that the azimuth or positional relationship indicated by the terms "upper", "lower", etc. are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of description of the present application and simplification of the description, and are not indicative or implying that the apparatus or element in question must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present application. Unless specifically stated or limited otherwise, the terms "mounted," "connected," and "coupled" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.
It should be noted that in this application, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The foregoing is merely a specific embodiment of the application to enable one skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The cutting detection method of the LED circuit board is characterized in that the LED circuit board is formed by arranging a plurality of full-color LED display units in an array mode, and the method comprises the following steps:
covering the LED circuit board with ink once, covering the metal via holes and the metal wires of the LED circuit board, and not covering the bonding pads; the primary ink (101) on the front surface of the adjacent full-color LED display structure is not connected, and in the single full-color LED display structure, the distance from the edge of the primary ink (101) on the front surface to the edge of the full-color LED display structure is larger than the preset distance;
performing secondary ink covering on the front surface of the LED circuit board covered by the primary ink so as to cover the area between the edges of two adjacent primary inks (101) on the front surface, wherein the secondary ink (102) is fluorescent ink;
and cutting the LED circuit board to obtain a plurality of full-color LED display units, respectively carrying out fluorescence detection on four sides of each full-color LED display unit, wherein all the full-color LED display units with fluorescence reactions on the sides are qualified products for cutting.
2. The method for detecting the cutting of the LED circuit board according to claim 1, wherein the LED circuit board is covered with the ink once, specifically comprising:
coating solder resist ink on the LED circuit board;
after a solder mask film is covered on the solder mask ink of the LED circuit board, performing exposure treatment; the solder mask comprises a plurality of groups of contour windowing lines, and each group of contour windowing lines corresponds to the contour of the shape of primary ink to be molded on one full-color LED display unit;
and developing the exposed LED circuit board to remove the solder resist ink corresponding to the area outside the outline windowing line, wherein the rest solder resist ink forms primary ink (101).
3. The method for detecting the cutting of the LED circuit board according to claim 1, wherein: the secondary ink (102) is a fluorescent ink that is excited only by invisible light.
4. The method for detecting the cutting of the LED circuit board according to claim 3, wherein the fluorescent detection is performed on four sides of each full-color LED display unit, respectively, specifically comprising:
the four sides of each full-color LED display unit are sequentially irradiated by adopting a light source of invisible light, and whether fluorescence reaction exists or not is identified by using CCD lenses respectively.
5. The method for detecting the cutting of the LED circuit board according to claim 4, wherein the method comprises the following steps: the invisible light is ultraviolet light or infrared light.
6. The method for detecting the cutting of the LED circuit board according to claim 1, further comprising, before the LED circuit board is subjected to one-time ink covering:
and acid washing, primary washing, plate grinding, secondary washing and drying are sequentially carried out on the LED circuit board.
7. The method for detecting the cutting of the LED circuit board according to claim 6, wherein the method comprises the following steps: the secondary water washing step comprises ultrasonic water washing and clear water rinsing.
8. An LED circuit board structure, comprising:
the LED circuit board is formed by arranging a plurality of full-color LED display units in an array manner;
the first ink layer is used for covering the metal via holes and the metal wires of the LED circuit board and does not cover the bonding pads; the first ink layers on the front surfaces of the adjacent full-color LED display structures are not connected, and in the single full-color LED display structure, the distance from the edge of the first ink layer on the front surface to the edge of the full-color LED display structure is larger than a preset distance;
and the second ink layer is used for covering the area between the edges of two adjacent first ink layers, and fluorescent ink is adopted for the second ink layer.
9. The LED circuit board structure of claim 8, wherein: the full-color LED display unit comprises an upper circuit board (1) and a lower circuit board (14), wherein the upper circuit board (1) is connected with the lower circuit board (14) through a metal via hole.
10. The LED circuit board structure according to claim 9, wherein the upper circuit board (1) is equally divided into four areas by a cross, and the upper circuit board (1) is provided with:
two die bond pad assemblies (2);
four pixel units, two of which are arranged on one die bonding pad assembly (2), wherein the four pixel units are respectively positioned in each area of the upper circuit board (1); each pixel unit comprises three light emitting chips, the three light emitting chips are all positioned on the same straight line, and the three light emitting chips in different pixel units are arranged in a translational symmetry mode;
the B electrode bonding pads are arranged in one-to-one correspondence with each light emitting chip and are respectively connected with the B electrodes of the corresponding light emitting chips, and the A electrodes of each light emitting chip are respectively connected with the die bonding pad assembly (2) where the A electrodes of the light emitting chips are positioned; the polarity of the A pole is opposite to that of the B pole.
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| CN113909155A (en) | 2022-01-11 |
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