A method for preparing metallized holes in a flexible circuit board

Abstract

The present invention provides a method for preparing metallized holes in a flexible circuit board, and relates to the technical field of preparing metallized holes. The preparation method comprises: obtaining a flexible circuit board, placing the flexible circuit board on a clamping device of a laser, and adjusting the laser parameters of the laser; setting the laser drilling path of the laser, and performing laser drilling processing on the position where the flexible circuit board needs to be drilled; plasma cleaning the inner wall of the drilled hole; copper plating the inner wall of the hole after plasma cleaning to form a metallized hole. The method for preparing metallized holes in a flexible circuit board provided by the present invention makes the process parameter window range of laser drilling larger, makes it easier to find suitable parameters, and reduces the number of experiments. And the laser ablation effect is uniform in the entire hole range, reducing the accumulation of thermal effects, thereby reducing the shrinkage size of the dielectric layer of the flexible circuit board, and improving the yield, quality and stability of laser drilling.

Description

Technical Field

[0001] The invention relates to the technical field of metallized hole preparation, and in particular to a method for preparing a metallized hole in a flexible circuit board. Background Art

[0002] Flexible Printed Circuit (FPC) is a highly reliable and extremely flexible printed circuit board made of polyimide (PI) or polyester film as the base material. It has the characteristics of high wiring density, light weight, thin thickness and good bendability.

[0003] FPC is mainly composed of dielectric layer and copper foil circuit. The dielectric layer is used to maintain the insulation between the copper foil circuit and each layer, commonly known as the substrate. FPC is divided into three types: single-sided board, double-sided board and multi-layer board. The single-sided board has one layer of copper foil circuit, the double-sided board has two layers of copper foil circuit, and the multi-layer board has multiple layers of copper foil circuit. Both double-sided board and multi-layer board are formed by laser drilling and electroplating to form metallized holes, so that the conductive circuit is formed between different layers of copper foil circuits. The dielectric layer is mainly composed of polyimide and glue. The dielectric layer of the double-sided board is usually composed of one layer of polyimide and one layer of glue. The adjacent two layers of copper foil circuits of the multi-layer board are usually composed of two layers of polyimide and two layers of glue. Due to the large difference in the physical properties between copper foil, polyimide and glue, the shrinkage of polyimide and glue during the laser drilling process is greater than that of copper foil. When the shrinkage of polyimide and glue exceeds a certain size, the metallized hole will be discontinuous after electroplating, resulting in no conduction between the adjacent two layers of copper foil circuits, thereby causing the flexible circuit board to be scrapped.

[0004] However, most of the existing technologies reduce the shrinkage size of the dielectric layer by adjusting the laser parameters. The process parameter window is narrow, and it is difficult to find relatively suitable parameters, which requires a lot of experiments. In addition, the existing process parameters have a serious cumulative thermal effect, resulting in large shrinkage size and instability of the dielectric layer. Summary of the invention

[0005] In view of this, the purpose of the present invention is to overcome the deficiencies in the prior art. The present application provides a method for preparing metallized holes in a flexible circuit board to solve the technical problems that most of the prior art reduces the shrinkage size of the dielectric layer by adjusting laser parameters, the process parameter window is narrow and the thermal effect accumulation is serious, which makes it difficult to find more suitable parameters, requires a large number of experiments, and the shrinkage size of the dielectric layer is large and unstable.

[0006] The present invention provides the following technical solutions:

[0007] A method for preparing a metallized hole in a flexible circuit board, the method comprising the steps of:

[0008] S1: Obtain a flexible circuit board, place the flexible circuit board on a clamping device of a laser, and adjust laser parameters of the laser;

[0009] S2: Setting a laser drilling path of the laser, and performing laser drilling processing on the position where the flexible circuit board needs to be drilled;

[0010] S3: plasma cleaning the inner wall of the hole drilled in step S2;

[0011] S4: copper plating is performed on the inner wall of the hole after plasma cleaning in step S3 to form a metallized hole.

[0012] In some embodiments of the present application, in step S2, the method of setting the laser drilling path includes:

[0013] The laser drilling path is set as concentric circles, the spacing of the concentric circles is set to increase in sequence along the direction toward the center of the circle, the spot interval of the concentric circles is set to increase in sequence along the direction toward the center of the circle, and the starting position of the spot of the concentric circle is set to be staggered by 90 degrees along the direction toward the center of the circle.

[0014] In some embodiments of the present application, in step S2, after laser drilling is performed on the position where the flexible circuit board needs to be drilled, the quality of the drilled hole is observed under a microscope;

[0015] The laser parameters and the laser drilling path are adjusted according to the observed quality results of the drilled holes, and laser drilling is then performed again until the bottom of the drilled holes is clean and free of residual glue.

[0016] In some embodiments of the present application, after the bottom of the drilled hole is clean and free of residual glue, the position of the hole drilled in the flexible circuit board is sliced ​​to observe the side wall morphology of the drilled hole under a microscope, and the laser parameters and the laser drilling path are adjusted according to the observed side wall morphology of the drilled hole, and then the laser drilling process is performed until the inward shrinkage size of the side wall of the drilled hole meets the preset requirements.

[0017] In some embodiments of the present application, after the inward shrinkage size of the side wall of the drilled hole meets the preset requirements, the inner wall of the drilled hole is sequentially subjected to plasma cleaning and copper plating.

[0018] In some embodiments of the present application, after the inner wall of the drilled hole is copper-plated, the position of the hole drilled in the flexible circuit board is sliced ​​to observe the copper plating of the side walls and bottom of the drilled hole under a microscope, and the laser parameters and the laser drilling path are adjusted according to the observed results of the copper plating of the side walls and bottom of the drilled hole, and then the laser drilling process is performed until the side walls and bottom of the drilled hole can be plated with copper.

[0019] In some embodiments of the present application, after the side walls and the bottom of the drilled hole can be plated with copper, the flexible circuit board is subjected to batch laser drilling, plasma cleaning and copper plating according to the adjusted laser parameters and the laser drilling path.

[0020] In some embodiments of the present application, after the flexible circuit board is subjected to batch laser drilling, plasma cleaning and copper plating, the flexible circuit board is cleaned.

[0021] In some embodiments of the present application, after the flexible circuit board is cleaned, a glue layer is applied on both sides of the flexible circuit board, and a protective film layer is covered on both sides of the flexible circuit board.

[0022] In some embodiments of the present application, in step S2, the diameter of the drilled hole is larger than the spot diameter of the laser.

[0023] The embodiments of the present invention have the following advantages:

[0024] The present application proposes a method for preparing metallized holes in a flexible circuit board, which reduces the shrinkage size of the dielectric layer of the flexible circuit board by adjusting the laser parameters of the laser and reasonably setting the laser drilling path, so that the shrinkage size of the dielectric layer of the flexible circuit board meets the requirements, thereby forming metallized holes after plasma cleaning and copper plating, thereby making the two adjacent layers of copper foil circuits of the flexible circuit board conductive.

[0025] Specifically, by adjusting the laser parameters of the laser and reasonably setting the laser drilling path, the distribution of laser energy during the laser drilling process is effectively adjusted, so that the process parameter window range of laser drilling becomes larger, it is easier to find suitable parameters, and the number of experiments is reduced. The laser ablation effect is uniform throughout the entire hole range, reducing the accumulation of thermal effects, thereby reducing the shrinkage size of the dielectric layer of the flexible circuit board and improving the yield, quality and stability of laser drilling. This avoids the technical problems that most of the existing technologies reduce the shrinkage size of the dielectric layer by adjusting the laser parameters, the process parameter window is narrow, and the thermal effect accumulation is relatively serious, which makes it difficult to find more suitable parameters, requires a large number of experiments, and the shrinkage size of the dielectric layer is large and unstable.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 A schematic diagram showing a process of preparing a metallized hole in a flexible circuit board in some embodiments of the present application is shown;

[0029] Figure 2 A schematic diagram of the structure of a flexible circuit board in some embodiments of the present application is shown;

[0030] Figure 3 A schematic diagram showing a laser drilling path in some embodiments of the present application;

[0031] Figure 4 A schematic diagram of the structure of a flexible circuit board after laser drilling in some embodiments of the present application is shown;

[0032] Figure 5 A schematic diagram of the structure of a flexible circuit board after copper plating in some embodiments of the present application is shown.

[0033] Description of main component symbols:

[0034] 10-flexible circuit board; 101-metallized hole; 20-laser drilling path; 201-concentric circles; 202-light spot. DETAILED DESCRIPTION

[0035] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0036] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. In contrast, when an element is referred to as being "directly on" another element, there is no intermediate element. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0037] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of the template are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0040] like Figures 1 to 5 As shown, in order to solve the technical problems that most of the prior art reduces the shrinkage size of the dielectric layer by adjusting the laser parameters, the process parameter window is narrow and the thermal effect accumulation is serious, which makes it difficult to find more suitable parameters, requires a lot of experiments, and the shrinkage size of the dielectric layer is large and unstable. The embodiment of the present application provides a method for preparing the metallized hole 101 of the flexible circuit board 10, and the preparation method includes the steps of:

[0041] S1: Obtain a flexible circuit board 10, place the flexible circuit board 10 on a clamping device of a laser, and adjust laser parameters of the laser.

[0042] Specifically, the flexible circuit board 10 can be a double-sided board or a multi-layer board. The double-sided board is composed of two layers of copper foil circuits and a dielectric layer sandwiched between the two layers of copper foil circuits. The dielectric layer is composed of a layer of polyimide and a layer of AD combination glue. The multi-layer board has multiple layers of copper foil circuits and dielectric layers. The adjacent two layers of copper foil circuits of the multi-layer board are composed of two layers of polyimide and two layers of glue. The clamping device of the laser can be a special clamp for the flexible circuit board 10. The special clamp can be a clamp combining an airbag and a suction cup, or a mechanical clamp, so that the flexible circuit board 10 remains fixed during the laser drilling process, thereby improving the accuracy and stability of the laser drilling. The laser parameters can be parameters such as laser pulses and laser energy.

[0043] It is understandable that the dielectric layer of a multilayer board is relatively thicker than that of a double-sided board, and more laser pulses or greater laser energy are required during the laser drilling process to achieve the effect of removing the upper copper foil and the dielectric layer. More laser pulses or greater laser energy acting on the multilayer board will lead to a greater thermal effect, which will cause the dielectric layer to shrink more than the copper foil. Therefore, this application selects a multilayer board with a relatively thick dielectric layer for experimentation.

[0044] S2: Setting the laser drilling path 20 of the laser, and performing laser drilling processing on the positions of the flexible circuit board 10 where holes need to be drilled.

[0045] Specifically, based on the physical difference between the copper foil and the dielectric layer of the flexible circuit board 10, the corresponding process parameters can be set by analyzing the hole formation process and the degree of ablation of the material by the laser energy during the laser drilling process, and the drilling effect corresponding to the process parameters can be verified by actual laser drilling. The laser parameters are adjusted and the laser drilling path 20 is reasonably set according to the distribution of laser energy, heat accumulation, and damage threshold of the material during the laser drilling process.

[0046] After adjusting the laser parameters of the laser and setting the laser drilling path 20, laser drilling is performed on the position where the flexible circuit board 10 needs to be drilled. By adjusting the laser parameters of the laser and reasonably setting the laser drilling path 20, the shrinkage size of the dielectric layer of the flexible circuit board 10 is reduced so that the shrinkage size of the dielectric layer of the flexible circuit board 10 meets the requirements, thereby forming a metallized hole 101 after plasma cleaning and copper plating, thereby making the two adjacent layers of copper foil circuits of the flexible circuit board 10 conductive.

[0047] By adjusting the laser parameters of the laser and reasonably setting the laser drilling path 20, the distribution of laser energy during the laser drilling process is effectively adjusted, so that the process parameter window range of laser drilling becomes larger, it is easier to find suitable parameters, and the number of experiments is reduced. The laser ablation effect is uniform throughout the entire hole range, reducing the accumulation of thermal effects, thereby reducing the shrinkage size of the dielectric layer of the flexible circuit board 10 and improving the yield, quality and stability of laser drilling. This avoids the technical problems that most of the existing technologies reduce the shrinkage size of the dielectric layer by adjusting the laser parameters, the process parameter window is narrow, and the thermal effect accumulation is relatively serious, which makes it difficult to find more suitable parameters, requires a large number of experiments, and the shrinkage size of the dielectric layer is large and unstable.

[0048] S3: Plasma cleaning is performed on the inner wall of the hole drilled in step S2.

[0049] Specifically, the inner wall of the hole drilled in step S2 is plasma cleaned to treat impurities, dust, etc. on the inner wall of the hole, thereby enhancing the adhesion of the inner wall of the hole, thereby pre-treating the subsequent copper plating of the inner wall of the hole.

[0050] It should be noted that after the inner wall of the hole is treated with plasma cleaning to remove impurities and dust, the inward shrinkage size of the dielectric layer will be slightly enlarged.

[0051] S4: copper plating is performed on the inner wall of the hole after plasma cleaning in step S3 to form a metallized hole 101 .

[0052] Specifically, the inner wall of the hole after plasma cleaning in step S3 is copper plated to form the metallized hole 101, thereby making the two adjacent layers of copper foil circuits of the flexible circuit board 10 conductive, thereby completing the preparation of the metallized hole 101 of the flexible circuit board 10.

[0053] It should be noted that the metallized hole 101 (PTH, Plated Through Hole) is also called copper plating, hole plating, plated through hole, and hole metallization. It refers to the process of using chemical plating and electroplating methods to plate a layer of conductive metal on the insulating hole wall of each layer of printed wire in the hole so that they can be reliably connected to each other.

[0054] like Figure 3 As shown, in one embodiment of the present application, optionally, in step S2, the method for setting the laser drilling path 20 includes:

[0055] S21: The laser drilling path 20 is set as concentric circles 201, the spacing of the concentric circles 201 is set to increase in sequence along the direction toward the center of the circle, the interval of the light spots 202 of the concentric circles 201 is set to increase in sequence along the direction toward the center of the circle, and the starting positions of the light spots 202 of the concentric circles 201 are set to be staggered by 90 degrees in sequence along the direction toward the center of the circle.

[0056] Specifically, the embodiment of the present application optimizes the laser drilling path 20 from three aspects to reduce the shrinkage size of the dielectric layer of the flexible circuit board 10 .

[0057] First aspect: by setting the laser drilling path 20 as concentric circles 201, and setting the spacing of the concentric circles 201 to increase in sequence along the direction toward the center of the circle, the laser ablation effect is made uniform, and the accumulation of heat in the dielectric layer at the edge of the hole is reduced, that is, the accumulation of thermal effects is reduced, thereby reducing the shrinkage size of the dielectric layer of the flexible circuit board 10.

[0058] Second aspect: by setting the intervals of the light spots 202 of the concentric circles 201 in increasing order in the direction toward the center of the circle, the laser ablation effect is made uniform, the accumulation of heat in the dielectric layer at the edge of the hole is reduced, and the accumulation of thermal effects is reduced, thereby reducing the shrinkage size of the dielectric layer of the flexible circuit board 10.

[0059] The third aspect: by staggering the starting positions of the light spots 202 of the concentric circles 201 by 90 degrees in the direction toward the center of the circles, the laser ablation effect is uniform throughout the entire hole, reducing the accumulation of heat in the dielectric layer at the edge of the hole, reducing the accumulation of thermal effects, and thus reducing the shrinkage size of the dielectric layer of the flexible circuit board 10.

[0060] The laser drilling path 20 obtained by optimizing the above three aspects reduces the shrinkage size of the dielectric layer of the flexible circuit board 10, effectively adjusts the distribution of laser energy during laser drilling, and makes the process parameter window range of laser drilling larger, making it easier to find suitable parameters and reducing the number of experiments. It also makes the laser ablation effect uniform in the entire hole range, reduces the accumulation of thermal effects, thereby reducing the shrinkage size of the dielectric layer of the flexible circuit board 10 and improving the yield, quality and stability of laser drilling.

[0061] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, in one embodiment of the present application, optionally, in step S2, after laser drilling is performed on the position where the flexible circuit board 10 needs to be drilled, the quality of the drilled hole is observed under a microscope;

[0062] The laser parameters and the laser drilling path 20 are adjusted according to the observed quality results of the drilled holes, and laser drilling is then performed again until the bottom of the drilled holes is clean and free of residual glue.

[0063] Specifically, by observing the quality and effect of the drilled holes under a microscope, and adjusting the laser parameters of the laser and the laser drilling path 20 according to the observed quality results of the drilled holes, the laser drilling process is performed again until the bottom of the drilled holes is clean and free of residual glue, so as to facilitate subsequent copper plating after plasma cleaning, thereby forming a metallized hole 101, thereby enabling conduction between two adjacent layers of copper foil circuits of the flexible circuit board 10.

[0064] like Figure 3 and Figure 4As shown, in the above-mentioned embodiment of the present application, optionally, after the bottom of the drilled hole is clean and free of residual glue, the position of the hole drilled in the flexible circuit board 10 is sliced ​​to observe the side wall morphology of the drilled hole under a microscope, and the laser parameters and the laser drilling path 20 are adjusted according to the observed side wall morphology of the drilled hole, and then the laser drilling process is performed until the inward shrinkage size of the side wall of the drilled hole meets the preset requirements.

[0065] Specifically, the position of the hole drilled in the flexible circuit board 10 is sliced, and the side wall morphology of the drilled hole is observed under a microscope, that is, the side wall shrinkage size of the hole is observed or measured to see whether it meets the preset requirements. If it does not meet the preset requirements, the laser parameters of the laser and the laser drilling path 20 are adjusted according to the observed side wall morphology of the drilled hole, and then the laser drilling process is continued. The experiment is repeated until the side wall shrinkage size of the drilled hole meets the preset requirements, so that copper can be plated after ion cleaning, thereby forming a metallized hole 101, thereby making the two adjacent layers of copper foil circuits of the flexible circuit board 10 conductive.

[0066] like Figure 4 and Figure 5 As shown, in the above-mentioned embodiment of the present application, optionally, after the inward shrinkage size of the side wall of the drilled hole meets the preset requirements, the inner wall of the drilled hole is sequentially plasma cleaned and copper plated.

[0067] Specifically, when the inward shrinkage size of the side wall of the drilled hole meets the preset requirements, the inner wall of the drilled hole is sequentially plasma cleaned and copper plated to form a continuous metallized hole 101, so that the two adjacent layers of copper foil circuits of the flexible circuit board 10 are connected through the metallized hole 101.

[0068] like Figure 4 and Figure 5 As shown, in the above-mentioned embodiment of the present application, optionally, after the inner wall of the drilled hole is copper-plated, the position of the hole drilled in the flexible circuit board 10 is sliced ​​to observe the copper plating of the side wall and the bottom of the drilled hole under a microscope, and the laser parameters and the laser drilling path 20 are adjusted according to the observed results of the copper plating of the side wall and the bottom of the drilled hole, and then the laser drilling process is performed until the side wall and the bottom of the drilled hole can be plated with copper.

[0069] Specifically, after the inner wall of the drilled hole is copper-plated, the position of the hole drilled in the flexible circuit board 10 is sliced, and the copper plating of the side walls and bottom of the drilled hole is observed under a microscope, that is, whether the side walls and bottom of the drilled hole are plated with copper, and whether the metallized hole 101 is continuous. If it does not meet the preset requirements, the laser parameters of the laser and the laser drilling path 20 are adjusted according to the observed results of the copper plating on the side walls and bottom of the drilled hole, and then the laser drilling process is continued. After plasma cleaning, the copper plating is performed again, and then the slices are observed under a microscope to see whether it meets the preset requirements. The experiment is repeated until the side walls and bottom of the drilled hole can be plated with copper and the metallized hole 101 is continuous, so that the two adjacent layers of copper foil circuits of the flexible circuit board 10 are electrically conductive.

[0070] like Figure 5 As shown, in the above-mentioned embodiment of the present application, optionally, after the side walls and the bottom of the drilled hole can be plated with copper, the flexible circuit board 10 is subjected to batch laser drilling, plasma cleaning and copper plating according to the adjusted laser parameters and the laser drilling path 20.

[0071] Specifically, after the side walls and bottom of the drilled holes can be plated with copper, the flexible circuit board 10 is subjected to batch drilling, plasma cleaning and copper plating according to the laser parameters and laser drilling path 20 obtained by experimental adjustment, so as to realize batch preparation of metallized holes 101 for the flexible circuit board 10.

[0072] In the above-mentioned embodiment of the present application, optionally, after the flexible circuit board 10 is subjected to batch laser drilling, plasma cleaning and copper plating, the flexible circuit board 10 is cleaned.

[0073] Specifically, after the flexible circuit board 10 is subjected to batch laser drilling, plasma cleaning and copper plating, the flexible circuit board 10 is cleaned to remove dust, impurities or residual glue on the flexible circuit board 10, thereby facilitating the subsequent application of glue and the application of a protective film.

[0074] In the above embodiment of the present application, optionally, after the flexible circuit board 10 is cleaned, a glue layer is applied on both sides of the flexible circuit board 10 , and a protective film layer is covered on both sides of the flexible circuit board 10 .

[0075] Specifically, after the flexible circuit board 10 is cleaned, the adhesive layer is applied on both sides of the flexible circuit board 10 so that the protective film layer is firmly bonded to the flexible circuit board 10 through the adhesive layer. By covering the protective film layer on both sides of the flexible circuit board 10, the flexible circuit board 10 is insulated and protected. Exemplarily, the material used for the protective film layer may be polyimide, and the material used for the adhesive layer may be AD composite adhesive.

[0076] like Figure 3 As shown, in one embodiment of the present application, optionally, in step S2, the diameter of the drilled hole is larger than the diameter of the laser spot 202.

[0077] Specifically, by setting the diameter of the hole drilled by laser processing to be larger than the diameter of the laser spot 202, the diameter of the drilled hole is much larger than the diameter of the laser spot 202, so that the diameter of the spot 202 is smaller, and the corresponding laser pulse or laser energy is smaller, which is conducive to adjusting the distribution of laser energy during laser drilling by setting the laser drilling path 20, so that the process parameter window range of laser drilling becomes larger, it is easier to find suitable parameters, and the number of experiments is reduced. And the laser ablation effect is uniform in the entire hole range, reducing the accumulation of thermal effects, thereby reducing the shrinkage size of the dielectric layer of the flexible circuit board 10, and improving the yield, quality and stability of laser drilling.

[0078] In summary, the method for preparing metallized holes in a flexible circuit board provided in the present application reduces the shrinkage size of the dielectric layer of the flexible circuit board by adjusting the laser parameters of the laser and reasonably setting the laser drilling path, so that the shrinkage size of the dielectric layer of the flexible circuit board meets the requirements, thereby forming metallized holes after plasma cleaning and copper plating, thereby making the two adjacent layers of copper foil circuits of the flexible circuit board conductive.

[0079] Specifically, by adjusting the laser parameters of the laser and reasonably setting the laser drilling path, the distribution of laser energy during the laser drilling process is effectively adjusted, so that the process parameter window range of laser drilling becomes larger, it is easier to find suitable parameters, and the number of experiments is reduced. The laser ablation effect is uniform throughout the entire hole range, reducing the accumulation of thermal effects, thereby reducing the shrinkage size of the dielectric layer of the flexible circuit board and improving the yield, quality and stability of laser drilling. This avoids the technical problems that most of the existing technologies reduce the shrinkage size of the dielectric layer by adjusting the laser parameters, the process parameter window is narrow, and the thermal effect accumulation is relatively serious, which makes it difficult to find more suitable parameters, requires a large number of experiments, and the shrinkage size of the dielectric layer is large and unstable.

[0080] In all examples shown and described herein, any specific values ​​should be interpreted as merely exemplary and not as limiting, and thus other examples of the exemplary embodiments may have different values.

[0081] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0082] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing a metallized hole in a flexible circuit board, characterized in that: The preparation method comprises the steps of: S1: Obtain a flexible circuit board, place the flexible circuit board on a clamping device of a laser, and adjust laser parameters of the laser; S2: Setting the laser drilling path of the laser, and performing laser drilling processing on the position where the flexible circuit board needs to be drilled; observing the quality of the drilled hole under a microscope, adjusting the laser parameters and the laser drilling path according to the observed quality results of the drilled hole, and then performing laser drilling processing until the bottom of the drilled hole is clean and free of residual glue; slicing the position of the hole drilled in the flexible circuit board to observe the side wall morphology of the drilled hole under a microscope, adjusting the laser parameters and the laser drilling path according to the observed side wall morphology of the drilled hole, and then performing laser drilling processing until the inward shrinkage size of the side wall of the drilled hole meets the preset requirements; S3: sequentially performing plasma cleaning and copper plating on the inner wall of the drilled hole; S4: Slicing the position of the hole drilled in the flexible circuit board to observe the copper plating of the side wall and the bottom of the drilled hole under a microscope, adjusting the laser parameters and the laser drilling path according to the observed copper plating results of the side wall and the bottom of the drilled hole, and then performing laser drilling processing until the side wall and the bottom of the drilled hole can be plated with copper; Wherein, in step S2, the method for setting the laser drilling path includes: The laser drilling path is set as concentric circles, the spacing of the concentric circles is set to increase in sequence along the direction toward the center of the circle, the spot interval of the concentric circles is set to increase in sequence along the direction toward the center of the circle, and the starting position of the spot of the concentric circle is set to be staggered by 90 degrees along the direction toward the center of the circle.

2. The method for preparing metallized holes in a flexible circuit board according to claim 1, characterized in that: After the sidewalls and the bottom of the drilled holes are plated with copper, the flexible circuit board is subjected to batch laser drilling, plasma cleaning and copper plating according to the adjusted laser parameters and the laser drilling path.

3. The method for preparing metallized holes in a flexible circuit board according to claim 2, characterized in that: After the flexible circuit board is subjected to batch laser drilling, plasma cleaning and copper plating, the flexible circuit board is cleaned.

4. The method for preparing metallized holes in a flexible circuit board according to claim 3, characterized in that: After the flexible circuit board is cleaned, a glue layer is applied on both sides of the flexible circuit board, and a protective film layer is covered on both sides of the flexible circuit board.

5. The method for preparing metallized holes in a flexible circuit board according to claim 1, characterized in that: In step S2, the diameter of the drilled hole is larger than the spot diameter of the laser.

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