Manufacturing method of ultrathin circuit board for high-precision LED screen

Abstract

The invention discloses a manufacturing method of an ultrathin circuit board for a high-precision LED screen, which comprises the following steps of: taking a double-sided copper-clad plate, and manufacturing circuit patterns on copper layers on two sides of the double-sided copper-clad plate corresponding to micropore patterns to form a pattern plate; soaking the pattern plate into a strong alkali solution to form a dissolving plate; spraying the dissolving board, carrying out plasma treatment and electroplating, and carrying out post-process processing to form a circuit board; an insulating dielectric layer is exposed through etching, then a strong alkali solution is used for dissolution, finally, the insulating dielectric layer is removed through flushing, hole walls are subjected to plasma treatment, micro holes are electroplated and filled, a structure of replacing blind holes with through holes is formed, the whole process is effectively matched with the sequential processes, and the processes of laser ablation, polishing, micro-etching finishing of electroplating protrusions and the like do not exist in the manufacturing process. The machining process is relatively mild, the machining precision is controllable, the machining precision of the micro-hole is effectively improved, the hole wall is smoother, and the problems that in the prior art, the ablation range of laser drilling on the insulating medium layer is too large, hole shape deformation is generated, and the hole wall roughness is too large are solved.

Description

Technical Field

[0001] The present invention relates to the field of circuit board manufacturing, and particularly to a manufacturing method for an ultra-thin circuit board for high-precision LED screens. Background Art

[0002] In the context of the continuous development of LED display technology, the demand for higher resolution and finer display effects has promoted the need for high-precision interconnection solutions. However, traditional thick circuit boards and large via structures cannot meet these requirements. Ultra-thin circuit boards are often used as the support carrier circuit boards for LED light sources. Therefore, an ultra-thin circuit board with blind holes to achieve double-sided copper conduction (the diameter of the blind holes is less than 50 μm) has been designed to achieve higher resolution, better optical performance, and high-density wiring design.

[0003] A common manufacturing method for the blind holes of such ultra-thin circuit boards for LED screens is as follows: First, etch one side of the copper, use a laser drilling method to burn off the insulating dielectric layer, and then perform electroplating on the holes to form blind holes.

[0004] However, due to the relatively small hole diameter of the blind holes in this type of design, when using laser drilling, the laser spot is relatively large, resulting in an overly large ablation range of the insulating dielectric layer during drilling, and problems such as hole shape deformation and excessive hole wall roughness.

[0005] Therefore, to solve the above-mentioned problems, a manufacturing method for an ultra-thin circuit board for high-precision LED screens is required. Summary of the Invention

[0006] The present invention aims to solve the problems such as hole shape deformation and excessive hole wall roughness easily caused by laser ablation during the processing of blind holes in the existing ultra-thin circuit boards for high-precision LED screens, and proposes a manufacturing method for an ultra-thin circuit board for high-precision LED screens. The circuit board is designed with a micro-hole pattern, and the diameter of the micro-hole pattern is less than 50 μm. The manufacturing method includes the following steps: S10: Take a double-sided copper clad laminate, with an insulating dielectric layer in the middle. Make circuit patterns corresponding to the micro-hole pattern on the two copper layers of the double-sided copper clad laminate to form an etched copper pattern, and the whole board forms a pattern board. S20: Immerse the pattern board in a strong alkali solution to form a dissolved board. S30: Spray the dissolved board, then perform plasma treatment and electroplating, and through subsequent process processing, form the circuit board.

[0007] Further, take an insulating board, drill through holes corresponding to the micro-hole pattern to form a support board; the spraying is as follows: Adjacent to one side of the dissolved board, set the support board, with the through holes corresponding to the micro-hole pattern, and then perform the spraying.

[0008] Further, the diameter of the through hole is larger than the diameter of the micro-hole pattern.

[0009] Further, the spraying is performed by flushing with a high-pressure water gun.

[0010] Further, after the spraying, insulating through holes are formed in the insulating dielectric layer corresponding to the etched copper pattern, and the diameter of the insulating through holes is smaller than that of the etched copper pattern.

[0011] Further, the immersion is carried out by immersing the pattern board in the strong alkali solution for 5 min to 10 min, and the temperature of the strong alkali solution is 80°C to 95°C, and the mass ratio of the alkaline compound component in the strong alkali solution is 5% to 10%.

[0012] Further, the alkaline compound component of the strong alkali solution is NaOH, KOH or quaternary ammonium base.

[0013] Further, the material of the insulating dielectric layer is FR-4 or polyimide.

[0014] Further, the thickness of the surface copper layer of the double-sided copper clad laminate is 5 μm to 10 μm thinner than the designed final copper thickness.

[0015] Further, the electroplating is pulse electroplating.

[0016] In the technical solution of the present invention, the thickness of the surface copper layer of the double-sided copper clad laminate is thinner than the designed copper thickness, which effectively cooperates with the electroplating in the subsequent process to form more plating on the surface copper layer, so that the copper thickness provided by the final circuit board meets the design requirements; the insulating dielectric layer corresponding to the etched copper pattern is exposed by etching, then dissolved in cooperation with the strong alkali solution, and finally the exposed insulating dielectric layer is removed by flushing. The hole wall is treated with plasma and then electroplated to fill the micro-holes, forming a structure that uses through holes instead of blind holes, and forming a method of chemical etching instead of laser ablation. There are no processes such as laser ablation, grinding, and micro-etching to trim electroplating protrusions in the whole manufacturing process. The processing process is relatively gentle and the processing accuracy is controllable, effectively improving the processing accuracy of the micro-holes, making the formed hole wall smoother, and solving the problems of excessive ablation range of the insulating dielectric layer by laser drilling in the prior art, such as hole shape deformation and excessive roughness of the hole wall; the front and rear processes of the overall process form an effective cooperation to produce high-precision filled micro-holes. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0018] Figure 1 Schematic diagram of the process flow according to an embodiment of the present invention; Figure 2 Schematic cross-sectional structure diagram of the graphic board according to an embodiment of the present invention; Figure 3 Schematic cross-sectional structure diagram of the dissolution board according to an embodiment of the present invention; Figure 4 Schematic cross-sectional structure diagram of the spray board according to an embodiment of the present invention Figure 5 Schematic cross-sectional structure diagram of the plasma board according to an embodiment of the present invention; Figure 6 Schematic cross-sectional structure diagram of the circuit board according to an embodiment of the present invention.

[0019] Explanation of the reference numerals in the drawings:

[0020] The realization of the object of the present invention, its functional features and advantages will be further described with reference to the embodiments and the accompanying drawings. Specific embodiments

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] It should be noted that all directional indications (such as up, down, left, right, front, back, inside, outside, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0023] In addition, the descriptions such as "first" and "second" in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0024] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0025] Please refer to Figure 1 , Figure 1 which is a schematic process flow diagram of an embodiment of the present invention.

[0026] The ultra-thin circuit board for high-precision LED screens according to the embodiment of the present invention is designed with a micro-hole pattern, and the diameter of the micro-hole pattern is less than 50 μm. The manufacturing method includes using the steps and processes in Figure 1 to implement. The following will further explain the steps and processes in Figure 1 step by step.

[0027] Please refer to Figure 2 , Figure 2 which is a schematic cross-sectional structure diagram of the graphic board of the embodiment of the present invention.

[0028] S10: Take a double-sided copper clad laminate, the middle layer of which is an insulating dielectric layer 1030. Make circuit patterns corresponding to the micro-hole patterns on the copper layers on both sides of the double-sided copper clad laminate to form an etched copper pattern 1010, thus forming a graphic board 10.

[0029] By etching the copper layer on the surface copper layer 1020 corresponding to the micro-hole pattern, the insulating dielectric layer 1030 in the micro-hole pattern area is exposed, providing a processing basis for etching the insulating dielectric layer 1030 with a strong alkali solution in the subsequent process.

[0030] Optionally, the material of the insulating dielectric layer 1030 of the double-sided copper clad laminate is FR-4 or polyimide, and the thickness of the insulating dielectric layer 1030 is 10 μm to 100 μm, preferably 20 μm, 30 μm or 50 μm.

[0031] It should be noted that since the diameter of the micro-holes is small, after electroplating and filling in the subsequent process, the surface copper layer 1020 is correspondingly plated with an additional layer of copper. Therefore, in this embodiment, the thickness of the surface copper layer 1020 of the double-sided copper clad laminate is 5 μm to 10 μm thinner than the designed final copper thickness, which effectively cooperates with the electroplating in the subsequent process that will plate about 10 μm to 15 μm more copper on the surface copper layer 1020, so that the final copper thickness provided by the circuit board 50 meets the design requirements. Generally, the final copper thickness of the ultra-thin circuit board for high-precision LED screens is generally 15 μm to 30 μm, so a double-sided copper clad laminate with a surface copper thickness of 5 μm to 25 μm is selected.

[0032] Please refer to Figure 3 , Figure 3 which is a schematic cross-sectional structure diagram of the dissolved board of the embodiment of the present invention.

[0033] S20: Immerse the graphic board 10 in a strong alkali solution to form a dissolved board 20.

[0034] Immerse the graphic board 10 in a strong alkaline solution. Utilizing the differences between materials, the alkaline compound can selectively dissolve and etch the insulating dielectric layer 1030 corresponding to the copper pattern 1010 without significantly affecting the copper layer on the surface, thereby forming the microporous structure in the desired preliminary form.

[0035] Optionally, the alkaline compound component of the strong alkaline solution is NaOH, KOH, or quaternary ammonium base.

[0036] Since the micropores are very small, in order to ensure their dimensional accuracy, factors such as solution concentration, temperature, and immersion time must be precisely controlled. Therefore, in the immersion process of this embodiment, the graphic board is immersed in the strong alkaline solution for 5 minutes to 10 minutes, and the temperature of the strong alkaline solution is 80°C to 95°C, and the mass ratio of the alkaline compound component of the strong alkaline solution is 5% to 10%. The 5% to 10% mass ratio of the alkaline compound concentration in combination with the 5-minute to 10-minute immersion time not only ensures sufficient dissolution ability to dissolve the insulating dielectric layer 1030 corresponding to the etched copper pattern 1010 but also avoids excessive penetration and dissolution of the inner wall of the hole, which may affect the subsequent electroplating process. At the same time, maintaining the temperature at a relatively high 80°C to 95°C can accelerate the chemical reaction rate and make the dissolution faster.

[0037] Optionally, conditions of rocking or vibration can be added during the immersion process, that is, one or more graphic boards 10 can be fixed to a frame, and a rocking and vibration device can be set for the frame; this can further improve the processing efficiency and effect of the immersion.

[0038] Please refer to Figure 4 、 Figure 5 and Figure 6 , Figure 4 , which is a schematic cross-sectional structure diagram of the spray board according to the embodiment of the present invention; Figure 5 , which is a schematic cross-sectional structure diagram of the plasma board according to the embodiment of the present invention; Figure 6 , which is a schematic cross-sectional structure diagram of the circuit board according to the embodiment of the present invention.

[0039] S30: Spray the dissolved board 20 to form a spray board 30, form insulating through-holes 3010 in the area corresponding to the etched copper pattern 1010, then perform plasma treatment to form a plasma board 40, form micropores 4010, and then perform electroplating. After subsequent processing, a circuit board 50 is formed.

[0040] Spray rinsing, as an important process, is used to remove the dissolved insulating dielectric layer 1030 and other contaminants, which is directly related to the electroplating quality of the subsequent process and can effectively avoid problems such as poor electroplating that may occur during the electroplating process. Then, plasma treatment can be used to activate, remove, and trim the insulating dielectric layer, improve the flatness and activity of the hole wall, and provide a basis for improving the adhesion of the subsequent electroplating layer.

[0041] In one embodiment, before flushing the dissolution plate 20, first take an insulating plate, drill through holes corresponding to the micro-hole pattern to form a support plate; dispose the support plate adjacent to one side of the dissolution plate 20, with the through holes corresponding to the micro-hole pattern, and then perform spraying. By using the support plate during the spraying process, physical support is provided for the plate body of the dissolution plate 20 when it bears the impact force of the water flow, which also helps maintain the stability of the overall structure and improves the consistency and reliability of the micro-hole pattern.

[0042] Further, the diameter of the through hole is larger than the diameter of the micro-hole pattern, which can promote the smooth passage of the liquid during spraying and ensure the thorough cleaning of the insulating dielectric layer 1030 after dissolution.

[0043] Optionally, the diameter of the through hole is 50 μm to 200 μm larger than the diameter of the micro-hole pattern on one side.

[0044] In this embodiment, the spraying is to use a high-pressure water gun to flush. The high-speed water flow generated by the high-pressure water gun can directly impact the insulating dielectric layer 1030 after dissolution, thereby effectively removing the dissolved insulating dielectric layer 1030 without causing damage to the surrounding structures.

[0045] Optionally, the pressure of the high-pressure water gun is 2 kg / cm 2 to 5 kg / cm 2 .

[0046] In this embodiment, after spraying, an insulating through hole 3010 is formed in the insulating dielectric layer 1030 corresponding to the etched copper pattern 1010. The diameter of the insulating through hole 3010 is smaller than that of the etched copper pattern 1010, leaving some insulating dielectric layer 1030 for the subsequent plasma treatment of the pore wall of the micro-hole 4010, avoiding excessive dissolution of the insulating dielectric layer 1030 and penetrating deep into the circuit board from the inner wall of the micro-hole 4010, which is not conducive to the subsequent electroplating process.

[0047] Preferably, the diameter of the insulating through hole 3010 is 5 μm to 10 μm smaller than the size of the etched copper pattern 1010.

[0048] In this embodiment, the plasma treatment can further refine and trim the insulating dielectric layer 1030 on the pore wall to make the pore wall smoother, meet the requirements for electroplating, help improve the adhesion between the subsequent electroplating layer and the underlying material, and at the same time improve the quality of the inner wall of the micro-hole 4010, enabling the metal to deposit more uniformly during electroplating.

[0049] Optionally, the parameters used in the plasma treatment are listed in the following table:

[0050] The plasma treatment is mainly a degumming process, which is divided into two stages: The main purpose of this stage is to remove the photoresist residues through oxygen plasma. The combination of high oxygen flow rate and appropriate power can effectively oxidize and remove the photoresist; In the second stage, in addition to continuing to use oxygen for further cleaning, carbon tetrafluoride is added to achieve a further cleaning effect.

[0051] Since pulse electroplating generally performs better than traditional direct current electroplating in filling the micro-holes 4010, due to its unique current characteristics, it preferentially electroplates the micro-holes 4010 first, and then increases the surface copper layer 1020. Moreover, the intermittent current of pulse electroplating helps to reduce the generation of hydrogen bubbles, which may cause voids or incomplete filling. Therefore, the electroplating in this embodiment is pulse electroplating, making the plating layer more uniform.

[0052] Optionally, the pulse electroplating parameters are: current density (ASD): 2.0 to 3.0, reverse wave / forward wave current ratio (%): 120 to 200, forward wave / reverse wave time ratio (ms): 8.0 / 0.3 to 15 / 0.5, throwing power (%): 100 to 150, total process time (min): 30 minutes to 60 minutes.

[0053] It should be noted that due to the high precision of the circuit board in the actual design and manufacturing process, the actual structure diagram and the dimensions such as the thickness between layers and the line width are in the micron level. For example, the thickness of each layer is generally between 5μm and 50μm. If the accompanying drawings of the specification are made according to the actual scale, there will be a problem of unclear illustration. Therefore, in order to more clearly show the implementation process of the manufacturing method, the accompanying drawings of this embodiment are all schematic diagrams with the technical features enlarged, which do not represent the size of the actual structure diagram, nor the enlarged diagram of the actual structure diagram in proportion.

[0054] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made under the inventive concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A method for manufacturing an ultra-thin circuit board for a high-precision LED screen, wherein the circuit board is designed with a micro-hole pattern, and the diameter of the micro-hole pattern is less than 50 μm, characterized in that: The production method comprises the following steps: S10: taking a double-sided copper-clad laminate, wherein the interlayer is an insulating dielectric layer, and making circuit patterns on the copper layers on both sides of the double-sided copper-clad laminate corresponding to the micro-hole patterns to form an etched copper pattern, and the whole board is formed into a patterned board; S20: soaking the graphic board in a strong alkaline solution to form a dissolved board; S30: spraying the dissolved board, plasma treating and electroplating the board, and then processing the board through a post-process to form the circuit board.

2. The method for manufacturing a high-precision ultra-thin circuit board for a LED screen according to claim 1, characterized in that: Take an insulating plate, drill through holes corresponding to the microporous pattern to form a support plate; the spraying is to arrange the support plate adjacent to one side of the dissolving plate, the through holes correspond to the microporous pattern, and then perform the spraying.

3. The method for manufacturing a high-precision ultra-thin circuit board for a LED screen as claimed in claim 2, characterized in that: The diameter of the through hole is greater than the diameter of the micro-hole pattern.

4. A method for manufacturing an ultra-thin circuit board for a high-precision LED screen as claimed in claim 1 or 2, characterized in that: The spraying is performed by washing with a high-pressure water gun.

5. A method for manufacturing an ultra-thin circuit board for a high-precision LED screen as claimed in claim 1 or 2, characterized in that: After the spraying, an insulating through hole is formed in the insulating dielectric layer corresponding to the etched copper pattern, and the diameter of the insulating through hole is smaller than that of the etched copper pattern.

6. The method for manufacturing a high-precision ultra-thin circuit board for a LED screen according to claim 1, characterized in that: The soaking is that the graphic board is immersed in the strong alkali solution for 5 minutes to 10 minutes, and the temperature of the strong alkali solution is 80° C. to 95° C., and the mass ratio of the alkaline compound component of the strong alkali solution is 5% to 10%.

7. A method for manufacturing an ultra-thin circuit board for a high-precision LED screen as claimed in claim 1 or 6, characterized in that: The alkaline compound component of the strong alkali solution is NaOH, KOH or quaternary ammonium alkali.

8. The method for manufacturing a high-precision ultra-thin circuit board for a LED screen according to claim 1, characterized in that: The insulating dielectric layer is made of FR-4 or polyimide.

9. The method for manufacturing a high-precision ultra-thin circuit board for a LED screen according to claim 1, characterized in that: The surface copper layer thickness of the double-sided copper clad laminate is 5 μm to 10 μm thinner than the designed finished copper thickness.

10. The method for manufacturing a high-precision ultra-thin circuit board for a LED screen according to claim 1, characterized in that: The electroplating is pulse electroplating.

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