Flexible circuit board with micro blind via and method of making same

Abstract

The application discloses a flexible circuit board with micro blind holes and a manufacturing method thereof. The method comprises the following steps: providing a flexible circuit substrate, sequentially performing laser drilling and hole-in glue removal treatment on the flexible circuit substrate to form micro blind holes on the flexible circuit substrate, based on a preset film flow, adopting a carbon film plating process to perform metalization treatment on the flexible circuit substrate after the glue removal treatment to obtain a metalized blind hole plate, and adopting a semi-filled copper plating process to plate copper on the metalized blind hole plate to obtain a target flexible circuit board. The application can break through the limitation of the existing blind hole aperture, reduce the blind hole aperture, improve the process capability of the flexible circuit board, and improve the problems of easy black holes and poor through hole capability with simplified production procedures and low cost, and significantly improve the copper plating effect of the micro blind holes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flexible circuit board manufacturing, in particular to a flexible circuit board with micro blind holes and a manufacturing method thereof. BACKGROUND

[0002] With the rapid development of science and technology, electronic products are developing towards "light, thin, short and small", and flexible circuit boards (FPC) are also developing towards high-density interconnection and miniaturization. Therefore, smaller through holes and thinner lines need to be introduced into the flexible circuit board. Flexible circuit boards are divided into single-layer boards (also known as single-sided boards), double-layer boards (also known as double-sided boards) and multi-layer boards. For non-single-layer boards (i.e. double-layer boards and multi-layer boards), the boards are connected through through holes. The types of through holes mainly include through holes, blind holes and buried holes. The plating effect of the through hole is a key factor for improving the process capability of the circuit board. Only the manufacturing capability of the through hole with a small aperture can occupy a favorable position in the industry competition. Therefore, reducing the aperture of the through hole is the trend. Currently, many manufacturers have begun to seek a manufacturing method for a through hole with a smaller aperture.

[0003] For a blind hole, the commonly used aperture of the smallest blind hole in the current industry flexible board product is 75 μm. For a smaller aperture blind hole (i.e. a blind hole with an aperture smaller than 75 μm, such as a blind hole with an aperture of 50 μm), also known as a micro blind hole, there are problems such as easy black hole and poor through hole plating capability in the manufacturing process. The throwing power (TP) refers to the thickness ratio between the copper (hole copper) in the micro blind hole and the copper (surface copper) on the surface of the flexible board after plating copper, as shown in Figure 1 , TP = C / D. In Figure 1 , 1 refers to a copper foil, 2 refers to a PI layer (i.e. polyimide), 3 refers to a glue layer, 4 refers to a copper plating layer, and 5 refers to a micro blind hole. In order to improve the problems of easy black hole and poor through hole plating capability, the existing patent CN104752234B provides a manufacturing method for a micro blind hole of a flexible packaging substrate, but there are steps such as copper reduction and multiple etching to reduce black holes, and the process is complex. In addition, flash plating and hole filling process are used during copper plating, which has high cost and poor copper plating effect. SUMMARY

[0004] Therefore, the embodiments of the present application provide a flexible circuit board with a micro blind hole and a manufacturing method thereof to solve the problems of complex manufacturing process, high cost and poor copper plating effect of the micro blind hole in the existing flexible circuit board.

[0005] The present application provides a manufacturing method of a flexible circuit board with a micro blind hole, comprising:

[0006] providing a flexible circuit substrate;

[0007] laser drilling and in-hole degumming treatment are sequentially performed on the flexible circuit substrate to form micro blind holes on the flexible circuit substrate;

[0008] Based on the preset film flow rate, a carbon film plating process is used to perform metallization treatment on the flexible circuit substrate after degumming treatment to obtain a metallized blind hole plate.

[0009] A semi-filled copper plating process is used to plate copper on the metallized blind hole plate to obtain a target flexible circuit board.

[0010] Optionally, the laser drilling and in-hole degumming treatment are sequentially performed on the flexible circuit substrate to form micro blind holes on the flexible circuit substrate, comprising:

[0011] A laser drilling process is used to perform laser drilling on the flexible circuit substrate to form the micro blind holes on the flexible circuit substrate;

[0012] The hole wall of the micro blind hole on the flexible circuit substrate is degummed;

[0013] The flexible circuit substrate is any one of a double-layer board and a multi-layer board with two or more layers;

[0014] The aperture range of the micro blind hole is 40-60 μm.

[0015] Optionally, when the flexible circuit substrate is specifically the double-layer board, the degumming treatment of the hole wall of the micro blind hole on the flexible circuit substrate comprises:

[0016] A degumming medicine is used to etch the hole wall of the micro blind hole at a preset etching line speed.

[0017] Optionally, the preset etching line speed ranges from 1.2 to 1.6 m / min.

[0018] Optionally, when the flexible circuit substrate is specifically the multi-layer board, the degumming treatment of the hole wall of the micro blind hole on the flexible circuit substrate comprises:

[0019] A mixed gas containing oxygen, nitrogen and CF4 gas is used to perform plasma etching on the hole wall of the micro blind hole for a preset processing time.

[0020] Optionally, the ratio of the oxygen, the nitrogen and the CF4 gas in the mixed gas is 8:1:1, and / or the preset processing time ranges from 16 to 22 min.

[0021] Optionally, the preset film flow rate is greater than 120 L / min.

[0022] Optionally, after the metalization treatment of the flexible circuit substrate after the adhesive removal treatment is performed by adopting the carbon coating process based on the preset fixing flow, the metalized blind hole plate is obtained, and the method further comprises the following steps of:

[0023] The AOI scanning machine is adopted to perform the defective product processing on the metalized blind hole plate.

[0024] Optionally, the semi-filled copper plating process is adopted to perform the copper plating on the metalized blind hole plate, and the target flexible circuit board is obtained.

[0025] The semi-filled plating solution is adopted to perform the copper plating on the metalized blind hole plate according to the preset copper plating line speed and the preset copper plating time, and the target flexible circuit board is obtained.

[0026] The semi-filled plating solution contains the preset proportion of sulfuric acid and copper sulfate.

[0027] Optionally, the preset proportion of the sulfuric acid and the copper sulfate in the semi-filled plating solution is 1:0.71-1:1.23; and / or, the preset copper plating line speed ranges from 0.5 to 2.5 m / min; and / or, the preset copper plating time ranges from 14 to 40 min.

[0028] In addition, the present application further provides a flexible circuit board with micro blind holes, which is made by the above-mentioned manufacturing method.

[0029] The present application has the following advantages: the micro blind holes are formed on the provided flexible circuit substrate by laser drilling, and the adhesive residue left on the hole wall of the micro blind hole after the drilling process is removed by the in-hole adhesive removal treatment, so that the micro blind hole is clean and smooth, facilitating the subsequent metalization treatment and copper plating; during the metalization treatment process, based on the preset fixing flow, the fixing flow can be used to promote the exchange of the plating solution and remove the graphite colloid with weak bonding force in the carbon coating process, effectively clean the micro blind hole wall and reduce the black hole problem; finally, the semi-filled copper plating process is adopted for copper plating, without the need to use the full-filled copper plating process to fill the micro blind hole, which can effectively overcome the poor through-hole capability problem in the full-filled copper plating, and at the same time, reduce the material cost of the filled copper plating, thereby achieving the purpose of significantly improving the copper plating effect of the micro blind hole.

[0030] The present application can break through the limitation of the existing blind hole diameter, reduce the blind hole diameter, improve the process capability of the flexible board, and simplify the production process and reduce the cost to improve the black hole and poor through-hole capability problem, and significantly improve the copper plating effect of the micro blind hole. BRIEF DESCRIPTION OF DRAWINGS

[0031] The features and advantages of the present application will be more clearly understood through the following detailed description with reference to the accompanying drawings, which are schematic and should not be understood as limiting the present application, and in which:

[0032] Figure 1 A model diagram showing the via capability of the micro blind via involved in the present application is shown;

[0033] Figure 2 A flow diagram showing the manufacturing method of the flexible circuit board with micro blind via in the first embodiment of the present application is shown;

[0034] Figure 3 A model diagram showing the aspect ratio of the micro blind via involved in the present application is shown;

[0035] Figure 4 A process flow chart showing the carbon film plating process in the first embodiment of the present application is shown;

[0036] Figure 5 A comparison diagram showing the defective product and the good product obtained by scanning the micro blind via by the AOI scanning machine in the first embodiment of the present application is shown;

[0037] Figure 6-1 An effect diagram showing the copper plating effect by using the full-filling copper plating process;

[0038] Figure 6-2 An effect diagram showing the copper plating effect by using the semi-filling copper plating process described in the present application;

[0039] Figure 7 An effect diagram showing the copper plating effect of the double-layer board by using the copper plating time of 14 min in the first embodiment of the present application.

[0040] BRIEF DESCRIPTION OF DRAWINGS

[0041] 1, copper foil, 2, PI layer, 3, adhesive layer, 4, copper plating layer, 5, micro blind via. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme of the embodiments of the present application will be described clearly and completely below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0043] Embodiment one

[0044] A manufacturing method of a flexible circuit board with micro blind via, as shown in Figure 2 , includes the following steps:

[0045] S1, providing a flexible circuit substrate.

[0046] Specifically, the flexible circuit substrate is any one of a double-layer board and a multi-layer board with two or more layers.

[0047] The double-layer board is a flexible circuit board with two layers of copper foils, and the multi-layer board is a flexible circuit board with two or more layers of copper foils. The boards are bonded together by glue and electrically connected by micro blind holes.

[0048] As shown in Figure 2 S2, laser drilling and hole glue removal are sequentially performed on the flexible circuit substrate to form micro blind holes on the flexible circuit substrate.

[0049] Preferably, S2 includes:

[0050] S21: using a laser process to perform laser drilling on the flexible circuit substrate to form the micro blind holes on the flexible circuit substrate;

[0051] S22: performing glue removal on the hole wall of the micro blind hole on the flexible circuit substrate.

[0052] Laser drilling by laser process is easy to control and adjust process parameters, which facilitates the production of small-diameter micro blind holes. Through glue removal, the residual glue slag formed on the hole wall due to laser can be removed, making the hole clean and smooth, facilitating subsequent carbon film plating and copper plating, and further improving the copper plating effect.

[0053] Specifically, the micro blind hole formed in S21 of the embodiment has a hole diameter ranging from 40 to 60 μm, a hole depth ranging from 37 to 47 μm (depending on the thickness of the flexible circuit substrate), and an aspect ratio ranging from 0.6 to 1.1, wherein the aspect ratio refers to the ratio between the hole depth and the hole diameter of the formed micro blind hole, represented by AR, as shown in Figure 3 AR = B / A. In Figure 3 , 1 refers to the copper foil, 2 refers to the PI layer, 3 refers to the glue layer, and 5 refers to the micro blind hole.

[0054] In one specific embodiment of S22 of the embodiment, when the flexible circuit substrate is specifically the double-layer board, S22 includes:

[0055] Using glue removal chemicals, the hole wall of the micro blind hole is etched at a preset etching line speed.

[0056] Through the above glue removal method, the residual glue slag on the micro blind hole formed by the double-layer board can be efficiently cleaned.

[0057] In the embodiment, the glue removal chemicals are potassium permanganate chemicals, the preset etching line speed ranges from 1.2 to 1.6 m / min, and the micro etching amount during etching is controlled to be 0.2 to 0.7 μm.

[0058] In another specific embodiment of S22, when the flexible circuit board is specifically the multilayer board, S22 includes:

[0059] The walls of the micro-blind holes are plasma etched using a mixed gas containing oxygen, nitrogen, and CF4 for a preset processing time.

[0060] Similarly, the above-mentioned adhesive removal method can effectively clean residual adhesive residue on the micro-blind holes formed by multilayer boards.

[0061] In this embodiment, the ratio of oxygen, nitrogen and CF4 in the mixed gas is 8:1:1, and / or the preset processing time ranges from 16 to 22 minutes.

[0062] like Figure 2 As shown, in step S3, based on a preset shadow flow rate, a carbon film deposition process is used to metallize the flexible circuit board after the adhesive removal process to obtain a metallized blind via board.

[0063] The preset fixing flow rate can be set to a higher flow rate according to the actual situation, which can promote chemical exchange, remove weakly bonded graphite colloids, solve the black hole problem, and thus help improve the subsequent copper plating effect.

[0064] Specifically, in this embodiment, the preset etching flow rate during the metallization process is greater than 120 L / min, and the corresponding processing line speed ranges from 1.3 to 1.9 m / min. The micro-etching amount during this process is controlled between 0.5 and 1.3 μm.

[0065] Specifically, the process flow for the carbon coating film fabrication in this embodiment is as follows: Figure 4 As shown, the specific operation methods for each step are the existing operation methods, and the specific details will not be repeated here.

[0066] Preferably, after S3, the method further includes:

[0067] An AOI scanner is used to process the metallized blind hole plate for defective products.

[0068] Based on AOI scanning machines (automatic optial inspection), the above-mentioned defective product rejection process can achieve defective product screening, thereby improving the reliability of flexible board quality throughout the entire production process.

[0069] Specifically, in this embodiment, a low-resolution (less than or equal to 3) AOI scanner is selected, which extends the scanning time and thus improves the AOI scanning capability for defective products with black holes. The comparison image of defective and good products obtained by scanning micro-blind holes using the AOI scanner in this embodiment is shown below.Figure 5 As shown, Figure 5 In the Chinese, "OK" indicates a good product, while "NG" indicates a defective product or a defective product with black holes.

[0070] Specifically, after the above-mentioned defective product rejection process, the following is also included:

[0071] The metallized blind hole plate, after passing the defective product rejection process, is sequentially subjected to dry film lamination, exposure development, and film removal.

[0072] Metallized blind via boards that have passed the defective product rejection process refer to qualified products (i.e., products with no black hole problems or very few black holes). Through the above-mentioned dry film lamination, exposure development and film removal, the circuit layout can be achieved before copper plating.

[0073] like Figure 2 As shown, in step S4, a semi-fill copper plating process is used to plate copper on the metallized blind via plate to obtain the target flexible circuit board.

[0074] Preferably, S4 includes:

[0075] Using a semi-fill solution, copper plating is performed on the metallized blind via board according to a preset copper plating line speed and a preset copper plating time to obtain the target flexible circuit board;

[0076] The semi-filled solution contains sulfuric acid and copper sulfate in a preset ratio.

[0077] Traditional copper plating processes use a full-fill solution to plate copper in blind or through holes (i.e., completely filling blind holes and making through holes fully connected). Figure 6-1 As shown, this is also known as full-fill copper plating. However, full-fill copper plating suffers from poor through-hole capability and high cost. In this embodiment, the partial-fill copper plating process uses a partial-fill solution to partially fill the micro-blind holes (i.e., the micro-blind holes are not completely filled) to achieve copper plating, as shown... Figure 6-2 As shown.

[0078] Using a semi-fill solution for copper plating significantly reduces production costs compared to the traditional full-fill copper plating process. It also effectively overcomes the problem of low through-hole capability caused by the large aspect ratio of micro blind holes, further improving the copper plating effect.

[0079] Preferably, the preset ratio of sulfuric acid and copper sulfate in the semi-filled solution is in the range of 1:0.71 to 1:1.23.

[0080] Specifically, in this embodiment, the composition and ratio of the semi-filling solution are compared with those of the fully-filling solution, as shown in Table 1.

[0081] Table 1. Comparison of the composition and ratio of semi-fill copper plating solution and full-fill copper plating solution.

[0082]

[0083]

[0084] According to Table 1, the preset ratio of sulfuric acid and copper sulfate in the half-filling plating solution (referred to as acid-copper ratio) is 1:1.1, and the acid-copper ratio of the full-filling plating solution (or hole-filling plating solution) is about 1:6.6. On the one hand, compared with the full-filling plating solution, the half-filling plating solution has a relatively high content of sulfuric acid and a larger solution conductivity; since the potential difference IR between the inside and outside of the hole is calculated by the formula: drop (wherein, J is the current density, K is the solution conductivity, d is the hole diameter, and L is the plate thickness), therefore, the solution conductivity of the half-filling plating solution is larger than that of the full-filling plating solution, and the potential difference between the inside and outside of the hole is lower, which can effectively improve the hole penetration capability. On the other hand, the content of CuSO4·5H2O in the half-filling plating solution is reduced, which can effectively save the production cost.

[0085] In addition, in the full-filling copper plating process, the additives in the full-filling plating solution have a lower plating solution tolerance, which is also easy to cause the phenomenon of sand copper (i.e., the copper plating layer is loose and has more cavities), and the sand copper can reduce the bonding force between the copper plating layer and the base material copper, and is easy to cause the phenomenon of separation of the copper plating layer from the base material copper. However, in the half-filling copper plating process, due to the difference (i.e., the composition and ratio of the additives) between the additives in the half-filling plating solution and the full-filling plating solution, the half-filling copper plating process has a higher plating solution tolerance, which can effectively avoid the occurrence of the sand copper phenomenon and reduce the quality risk.

[0086] Specifically, in the present embodiment, the preset copper plating line speed ranges from 0.5 to 2.5 m / min, and the preset copper plating time ranges from 14 to 40 min.

[0087] Compared with the traditional copper plating process, by adjusting the copper plating solution and the electroplating parameters, the half-filling copper plating process with the above-mentioned preset copper plating line speed and preset copper plating time can improve the hole penetration capability of the blind hole to a certain extent, and further improve the copper plating effect.

[0088] In the present embodiment, the preset copper plating time is 14 min, the half-filling plating solution is used for copper plating of the double-layer plate, and the copper plating effect diagram obtained is as shown in Figure 7 Figure 7 The hole penetration capability TP of the double-layer plate is improved.

[0089] Next, taking the double-layer plate and the multi-layer plate as the flexible circuit substrate to make 50 μm micro blind holes as examples, the complete manufacturing process of the present embodiment is described.

[0090] 1. The manufacturing process of 50 μm micro blind holes made of double-layer plate as flexible circuit substrate is as follows:

[0091] (1) Prepare a double-layer plate substrate. ​​

[0092] (2) Use ESI laser machine to make 50um blind via by laser drilling. See Table 2 for detailed parameters.

[0093] (3) Use desmear line to desmear the board obtained in (2). See Table 2 for detailed parameters.

[0094] (4) Use carbon film plating line to metalize the via wall by carbon film plating process. See Table 2 for detailed parameters.

[0095] (5) Use CAMTEK AOI scanner to perform secondary processing of defective products. See Table 2 for detailed parameters.

[0096] (6) Perform film pressing, exposure and development film removing processing on good products that have passed secondary processing of defective products in (5).

[0097] (7) Use semi-filled copper plating solution and MUKAI copper plating line to perform copper plating processing on the board in (6). See Table 2 for detailed parameters.

[0098] 2. The manufacturing process of 50um micro blind via using multilayer board as flexible circuit substrate is as follows:

[0099] (1) Prepare a multilayer board substrate.

[0100] (2) Use ESI laser machine to make 50um blind via by laser drilling. See Table 2 for detailed parameters.

[0101] (3) Use BOFFOTTO plasma etching to process the board obtained in (2) for 18 minutes with mixed gas of O2:CF4:N2=8:1:1. See Table 2 for detailed parameters.

[0102] (4) Use carbon film plating line to metalize the via wall by carbon film plating process. See Table 2 for detailed parameters.

[0103] (5) Use CAMTEK AOI scanner to perform secondary processing of defective products. See Table 2 for detailed parameters.

[0104] (6) Perform film pressing, exposure and development film removing processing on good products that have passed secondary processing of defective products in (5).

[0105] (7) Use semi-filled copper plating solution and DW copper plating line to perform copper plating processing on the board in (6). See Table 2 for detailed parameters.

[0106] Table 2 Detailed parameters of manufacturing 50um micro blind via using double-layer board and multilayer board as flexible circuit substrate respectively in this embodiment

[0107]

[0108] The manufacturing method of the flexible circuit board with micro blind via holes in the embodiment forms micro blind via holes on the provided flexible circuit board by laser drilling, and performs glue removal treatment in the hole, so as to remove the glue residue left on the hole wall of the micro blind via hole after the drilling process, so that the micro blind via hole is clean and smooth, facilitating subsequent metallization treatment and copper plating; during the metallization treatment process, based on the preset fixing flow, a higher fixing flow can be used to promote the exchange of the chemical solution, remove the graphite glue with weak bonding force in the carbon film plating process, effectively clean the hole wall of the micro blind via hole, and reduce the black hole problem; finally, semi-filling copper plating process is used for copper plating, and full-filling copper plating process is not needed for full hole filling of the micro blind via hole, which can effectively overcome the poor through-hole capability in full-filling copper plating, and at the same time, reduce the material cost of hole filling and copper plating, thereby achieving the purpose of significantly improving the copper plating effect of the micro blind via hole.

[0109] The embodiment can break through the limitation of the existing blind hole diameter, reduce the blind hole diameter, and improve the process capability of the flexible board. Without the need to set copper reduction and multiple etching to reduce black holes and the like, the production process is simplified and the low cost is used to improve the problems of easy black hole and poor through-hole capability, and the copper plating effect of the micro blind via hole is significantly improved.

[0110] Embodiment two

[0111] A flexible circuit board with micro blind via holes is manufactured by the manufacturing method of embodiment one.

[0112] The flexible circuit board of the embodiment has micro blind via holes with smaller hole diameters and better copper plating effects, can realize better electrical connection between the layers of the flexible circuit board, has better quality, helps the development of electronic products in the direction of "light, thin, short and small", and has good application prospects.

[0113] The manufacturing method of the embodiment is the same as that in embodiment one, and the details of the embodiment are described in detail in embodiment one and the specific description of Figures 1 to 7 , which will not be repeated here.

[0114] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and variations can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method of manufacturing a flexible circuit board having micro blind vias, comprising: The application relates to a flexible circuit board manufacturing method. ​ Providing a flexible circuit board; Performing laser drilling and hole glue removal on the flexible circuit board in sequence to form micro blind holes on the flexible circuit board; Based on a preset plating flow, a carbon film plating process is adopted to perform metallization treatment on the flexible circuit board after glue removal, so as to obtain a metallized blind hole plate; the preset plating flow is greater than 120 L / min; A semi-filled copper plating process is adopted to perform copper plating on the metallized blind hole plate, so as to obtain a target flexible circuit board; a semi-filled plating solution is adopted to perform copper plating on the metallized blind hole plate according to a preset copper plating line speed and a preset copper plating time, so as to obtain the target flexible circuit board; the semi-filled plating solution contains a preset proportion of sulfuric acid and copper sulfate, and the preset proportion ranges from 1:0.71 to 1:1.

23.

2. The method of claim 1, wherein the microvia is formed by a laser beam. The method comprises the following steps: Performing laser drilling on the flexible circuit board by adopting a laser process to form the micro blind holes on the flexible circuit board; Performing glue removal treatment on the hole wall of the micro blind hole on the flexible circuit board; The flexible circuit board is any one of a double-layer board and a multi-layer board with two or more layers; The aperture of the micro blind hole ranges from 40 to 60 mu m.

3. The method of claim 2, wherein the microvia is formed by a laser beam. When the flexible circuit board is the double-layer board, the glue removal treatment on the hole wall of the micro blind hole on the flexible circuit board comprises the following steps: Performing etching on the hole wall of the micro blind hole by adopting a glue removal plating solution according to a preset etching line speed; The preset etching line speed ranges from 1.2 to 1.6 m / min.

4. The method of claim 2, wherein the microvia is formed by a laser beam. When the flexible circuit board is the multi-layer board, the glue removal treatment on the hole wall of the micro blind hole on the flexible circuit board comprises the following steps: Performing plasma etching on the hole wall of the micro blind hole by adopting a mixed gas containing oxygen, nitrogen and CF4 gas according to a preset treatment time.

5. The method of claim 4, wherein the microvia is formed by a laser beam. The proportion of the oxygen, the nitrogen and the CF4 gas in the mixed gas is 8:1:1, and / or the preset treatment time ranges from 16 to 22 min.

6. The method of claim 1 to 5, wherein After the metallization treatment on the flexible circuit board after glue removal based on the preset plating flow by adopting the carbon film plating process to obtain the metallized blind hole plate, the method further comprises the following steps: Performing defect processing on the metallized blind hole plate by adopting an AOI scanning machine.

7. The method of claim 1 to 5, wherein The preset copper plating line speed ranges from 0.5 to 2.5 m / min; and / or the preset copper plating time ranges from 14 to 40 min.

8. A flexible circuit board having microvias, characterized by, The flexible circuit board is manufactured by adopting the manufacturing method in any one of claims 1 to 7.

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