Blind hole processing and manufacturing method of PCB (Printed Circuit Board)

Abstract

The invention relates to a blind hole processing and manufacturing method for a PCB, and the method comprises the following steps: S1, the surface of a copper foil of the PCB is coated with a protective film, the copper foil is alloy copper, or the thickness of the copper foil is greater than 70 microns, and the transparency of the protective film is greater than or equal to 90%; s2, identifying and positioning the position of a to-be-processed blind hole in the PCB to determine a blind hole alignment point; s30, an exposed area is machined on the protective film through a laser drilling machine, and the laser drilling machine is a UV laser drilling machine; s31, the exposed area corresponds to the position of the blind hole alignment point, and the UV laser drilling machine can drill the blind hole alignment point through the exposed area; s4, tearing off the protective film to obtain a blind hole; and S5, electroplating the obtained blind holes so as to form circuit conduction among all layers of the PCB. According to the blind hole processing and manufacturing method of the PCB provided by the invention, the problem that the periphery of an orifice is seriously blackened after the blind hole is drilled can be effectively improved, and the product yield of the PCB is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of blind hole processing of circuit boards, and in particular to a method for processing and manufacturing blind holes of PCB boards. Background Art

[0002] During current laser processing of blind vias on PCBs, the high temperatures and dust generated during the process inevitably cause copper slag to splash around the via openings, resulting in a blackened appearance around the openings. This is caused by oxidation of residual slag, or by impurities such as carbonized dielectric layers that cling to the surrounding area. Conventional methods typically involve micro-etching after laser drilling, which essentially removes any remaining blackened slag and foreign matter on the copper foil surface.

[0003] However, for some special copper foils, such as titanium copper and other alloy coppers or some copper foils with relatively large thickness, conventional micro-etching solutions are difficult to remove impurities on the surface of these alloy coppers. Compared with other ordinary copper foils, these alloy coppers require longer micro-etching time. Once the micro-etching time is too long, the copper foil will become thinner as a whole, affecting the subsequent performance of the PCB board (such as conductivity); and if the micro-etching time is not enough, it will make it impossible to completely remove foreign matter on the surface of the copper foil. In the subsequent blind hole electroplating process, since there are still foreign matter remaining on the surface, the electroplating effect will be poor, that is, after copper plating, it is easy to cause abnormal conditions such as hole cracking, which will directly affect the reliability and service life of the PCB board, resulting in reduced reliability and short service life.

[0004] Therefore, it is necessary to improve on the basis of the existing technology and provide a blind hole processing method that can improve the blackening around the hole mouth and better solve the problem of residual residue on the copper foil surface during the blind hole processing process. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a processing and manufacturing method that can effectively improve the blackening around the openings of blind holes in PCB boards.

[0006] In order to solve the above technical problems, the technical solution used in the present invention is:

[0007] A method for processing and manufacturing blind holes in a PCB board comprises the following steps:

[0008] S1: Apply a protective film to the copper foil surface of the PCB board, wherein the copper foil is an alloy copper, or the thickness of the copper foil is greater than 70 microns, and the transparency of the protective film is ≥90%;

[0009] S2: Identify and locate the position of the blind hole to be processed on the PCB board to determine the blind hole alignment point;

[0010] S30: machining an exposed area on the protective film by a laser drilling machine, wherein the laser drilling machine is a UV laser drilling machine;

[0011] S31: The exposed area corresponds to the position of the blind hole alignment point, and the UV laser drilling machine can drill the blind hole alignment point through the exposed area;

[0012] S4: Remove the protective film to obtain a blind hole;

[0013] S5: Electroplating is performed on the obtained blind holes to form circuit conduction between the various layers of the PCB.

[0014] Preferably, the protective film is made of a material that does not leave adhesive residue.

[0015] Preferably, the protective film has a viscosity lower than 0.5 N / cm and a thickness of 35 μm-45 μm.

[0016] Preferably, in step S2, identifying and locating the position of the blind hole specifically includes step S20: obtaining the position of the blind hole through the protective film by an optical detection mechanism of a laser drilling machine; the optical detection mechanism includes a low-power mirror and a high-power mirror, the low-power mirror is used to preliminarily scan the position of the blind hole alignment point to determine the first position area; the high-power mirror is used to accurately locate the position of the blind hole alignment point within the first position area.

[0017] Preferably, in step S2, identifying and locating the position of the blind hole specifically includes: fixing the PCB board in a first position area on the operating table, obtaining the position of the blind hole through the protective film by an optical detection mechanism of a laser drilling machine, the optical detection mechanism includes a high-power microscope, and the high-power microscope is used to accurately locate the position of the blind hole alignment point in the first position area.

[0018] Preferably, the laser power of the UV laser drilling machine when processing the exposed area on the protective film is 2.5±0.2W, and the defocus is 2±0.2mm; the diameter of the exposed area is larger than the diameter of the blind hole alignment point.

[0019] Preferably, in step S3, drilling the blind hole position to be processed specifically includes: drilling the hole using a laser drilling machine in a spiral processing path from inside to outside.

[0020] Preferably, the spiral processing path of the laser drilling machine is specifically as follows: the laser beam of the laser drilling machine takes the center point of the blind hole as the starting point, and performs at least one closed circular path processing along the first radius R1; and starts from the tangent point on the closed circular path, and expands outward multiple times along the spiral trajectory; when the spiral trajectory reaches the second radius R2, the end point of the spiral processing path automatically connects to the closed circular path with R2 as the radius.

[0021] Preferably, after the protective layer is applied to the copper foil surface of the PCB board, the method further includes step S10 of removing bubbles from the protective layer.

[0022] Preferably, the debubbling treatment is performed by roller pressing or vacuuming, and the roller pressing pressure is 0.3-0.4 MPa.

[0023] The beneficial effects of the present invention are mainly reflected in: the blind hole processing and manufacturing method of the PCB board provided by the present invention can effectively remove residual foreign matter around the hole opening during the blind hole processing of copper alloys such as titanium copper or thick copper, thereby ensuring the continuity and uniformity of the electroplated copper layer of the PCB board, ensuring the conductive performance of the circuit board, effectively improving the signal integrity, and effectively alleviating the serious blackening problem around the hole opening after blind hole drilling, thereby improving the product yield of the PCB. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of the preferred embodiments of the present invention shown in the accompanying drawings. The same reference numerals indicate the same parts throughout the accompanying drawings, and the drawings are not drawn to scale with actual size. The emphasis is on illustrating the subject matter of the present invention.

[0025] Figure 1 This is the effect diagram after laser processing of blind holes in Comparative Example 1;

[0026] Figure 2 This is a diagram showing the effect of laser processing of blind holes in Example 1;

[0027] Figure 3 A diagram showing the steps of the blind hole processing method of the present invention;

[0028] Figure 4 Schematic diagram of the spiral processing path of the laser drilling machine in an embodiment of the present invention;

[0029] Figure 5 Schematic diagram of the drilling processing path of the laser drilling machine in comparative example 2.

[0030] In the figure: PCB board 101, copper foil 102, and protective film 103. DETAILED DESCRIPTION

[0031] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings.

[0032] It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to the other element and integrated therewith, or there may be an intermediate element. The terms "mounted", "one end", "the other end" and similar expressions used herein are for illustrative purposes only.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0034] refer to Figure 3-4 The present invention provides a method for processing and manufacturing blind holes in a PCB board 101, comprising the following steps:

[0035] S1: A protective film 103 is applied to the surface of the copper foil 102 of the PCB 101. The protective film 103 can be made of a polyester film (PET) with silicone or a polyethylene-based material. The shape and size of the protective film 103 are compatible with the shape and size of the PCB 101. The copper foil 102 is a copper alloy (such as titanium copper), or the thickness of the copper foil 102 is greater than 50 microns (here referring to the thickness of the copper foil 102 located on the outermost surface of the PCB 101). The transparency of the protective film 103 is ≥90%. The use of a highly transparent protective film 103 prevents the protective film 103 from obscuring the blind via alignment points (the so-called blind via alignment points refer to the marking points on the PCB board for processing blind vias), allowing the laser drill to more accurately identify and locate the blind via locations, thereby improving processing accuracy. Furthermore, the use of a non-residue adhesive material prevents secondary contamination of the via openings when the protective film 103 is removed, ensuring the cleanliness of the copper surface and reducing the subsequent cleaning process of the copper foil 102 surface.

[0036] S2: Identify and locate the position of the blind hole to be processed on the PCB board 101 to determine the blind hole alignment point;

[0037] S30: A laser drilling machine (not shown) is used to process an exposed area (such as Figure 3In the process of research and development, the applicant of the present invention uses two laser drilling machines (UV laser drilling machine and CO2 laser drilling machine) to test the effects of the PCB board 101 which is also covered with the protective film 103. It is found that when the CO2 laser drilling machine is used for drilling, even under the same laser parameters, the laser energy of the CO2 laser drilling machine will always excessively burn the protective film 103 during the drilling process. This is because the energy heat influence range emitted by the laser is large, and the single infrared light spot diameter of the CO2 laser drilling machine is relatively large, which makes it easy for the energy to burn the protective film 103 during drilling, and ultimately causes residue to splash onto the surface of the copper foil 102 during drilling, so that the protective film 103 cannot play a good physical shielding role.

[0038] When using a UV laser drill for drilling, under the same laser parameters, the energy emitted by the UV laser drill has a smaller heat impact range and a smaller spot diameter, making it less likely to burn the protective film 103 during the drilling process. This allows the protective film 103 to play a good physical shielding role, resulting in more accurate drilling accuracy. This helps reduce defects such as short circuits and open circuits caused by blind hole position deviations or inaccurate drilling, helps improve the circuit performance of the circuit board, and makes the circuit board more stable and reliable. Therefore, in the present invention, it is preferred to use a UV laser drill for processing.

[0039] S31: The exposed area corresponds to the position of the blind hole alignment point, and the UV laser drilling machine can drill the blind hole alignment point through the exposed area. Specifically, an exposed area is pre-processed on the protective film 103. The exposed area is mainly used to expose the alignment point for blind hole processing, so that the laser beam of the laser drilling machine can pass through the exposed area and directly perform the next drilling work based on the alignment point;

[0040] S4: tear off the protective film 103 to obtain a blind hole;

[0041] S5: Electroplating is performed on the obtained blind holes to form circuit conduction between the various layers of the PCB.

[0042] As described above, in this embodiment, a protective film 103 is applied to the PCB 101 before blind via drilling. The protective film 103 covers the surface of the copper foil 102 (especially alloy copper such as titanium copper or thick copper foil 102) during laser drilling, directly preventing the high-temperature slag and carbonized foreign matter generated during the laser processing from splashing around the hole opening. This fundamentally reduces the blackening phenomenon caused by oxidation of the copper slag and carbonization of the dielectric layer. The subsequent micro-etching process allows for quicker cleaning of the remaining residue, resulting in better cleaning results and preventing cracking of the hole opening during the subsequent electroplating process, thereby ensuring the electrical conductivity of the circuit board. Because carbonized residue (such as carbon particles) in the blackened area may be conductive, inadequate cleaning during the micro-etching process may reduce the insulation resistance between adjacent lines or layers, leading to the risk of leakage current or short circuits in the circuit board, and also affecting signal transmission.

[0043] Compared with the prior art, the blind hole processing and manufacturing method provided by the present invention solves the problem of difficulty in removing surface residues of alloy copper or thick copper foil 102 after drilling through physical isolation and protection, thereby ensuring the thickness and stability of copper foil 102. After drilling, the protective film 103 can be removed to make the area around the hole mouth cleaner, reducing the impurity residue between the electroplating layer and the substrate, thereby reducing the risk of cracking of the hole mouth electroplating and improving the adhesion and conduction reliability of the blind hole electroplating. Traditional processing methods require long-term micro-etching to remove stubborn residues on the surface of the copper foil 102, which can easily cause the copper foil 102 to be too thin or not cleaned thoroughly, causing cracking of the hole mouth electroplating. Therefore, for alloys or thick copper foil 102 with strong micro-etching resistance such as titanium copper, the blind hole processing and manufacturing method provided by the present invention breaks the limitations of traditional micro-etching processes, effectively improves the problem of blackening of the hole mouth after blind hole drilling, and improves the subsequent electroplating effect and the performance and reliability of the finished PCB board 101.

[0044] In a preferred embodiment, the protective film 103 is made of a non-sticky material to avoid sticky residue on the surface of the copper foil 102 during the tearing process, thereby preventing contamination and affecting the quality and effect of drilling.

[0045] In a preferred embodiment, the viscosity of the protective film 103 is less than 0.5N / cm, and the thickness is 35μm-45μm. The low-viscosity protective film 103 is easy to apply and tear off, avoiding damage to the surface of the copper foil 102 due to excessive adhesion when the protective film 103 is torn off. This is especially important for brittle copper alloys such as titanium copper. It can prevent the impact of wrinkles (the so-called wrinkles refer to the local wrinkles, deformations or unevenness on the surface of the copper foil) on subsequent processes, because wrinkles may cause the focus to shift during laser drilling, resulting in deviations in the blind hole processing position, affecting the conductivity reliability of the circuit. At the same time, the thickness of the protective film 103 is between 35-45μm (micrometers), specifically 35μm, 40μm or 45μm. In this embodiment, the protective film 103 is preferably 40μm.

[0046] Before drilling, a laser drill is required to create an exposed area on the protective film 103 (that is, the laser drill first emits a laser beam to act on the protective film 103, causing the protective film 103 to burn through an area) to expose the blind hole alignment point. At this time, the laser energy only acts on the protective film 103 and does not directly act on the surface of the copper foil 102. If the protective film 103 is too thick (>45μm), it may affect the transmission of laser energy, resulting in the laser beam being unable to burn through the protective film 103 in one go, and the target point of the blind hole cannot be exposed, requiring secondary processing. Secondary processing or if the protective film 103 is too thin (<35μm), it may cause part of the laser beam energy to act on the surface of the copper foil 102, causing damage to the copper foil 102. As a result, during subsequent drilling, the laser drill cannot align with the blind hole alignment point, resulting in the inability to complete the drilling operation. If care is not taken, the circuit board may be scrapped.

[0047] Furthermore, the present invention provides two embodiments for identifying and locating blind holes:

[0048] In the first embodiment, in step S2, identifying and locating the position of the blind via specifically includes step S20: obtaining the position of the blind via through the protective film 103 using an optical detection mechanism of the laser drilling machine; the optical detection mechanism includes a low-power lens and a high-power lens, with the low-power lens being used to initially scan the position of the blind via alignment point over a large area to determine a first location region. Since the transparency of the protective film 103 is ≥90%, the optical detection signal penetration is ensured, preventing imaging blur during the low-power lens / high-power lens process, i.e., without affecting the imaging scanning and identification of the low-power lens or the high-power lens (the same principle applies in the next embodiment and will not be further described). In this case, the low-power lens can initially scan a large area of ​​the PCB board 101 to roughly determine the first location region (or approximate range) where the blind via is located. The high-power lens is used to accurately locate the position of the blind via alignment point within the first location region. When the low-power lens identifies the approximate region of the blind via, the high-power lens is switched to clearly identify the position range of the first region, thereby accurately locating the blind via alignment point.

[0049] In the second embodiment, in step S2, identifying and locating the position of the blind hole specifically includes: fixing the PCB board 101 in a first position area on the operating table, and obtaining the position of the blind hole through the protective film 103 by the optical detection mechanism of the laser drilling machine, wherein the optical detection mechanism includes a high-power microscope, and the high-power microscope is used to accurately locate the position of the blind hole alignment point in the first position area. Specifically, in this embodiment, the PCB board 101 can be fixed in the first position area on the operating table during the loading process by means of a set of nails (the so-called set of nails refers to: using the mutual cooperation of the positioning pins and the positioning holes on the PCB board 101 to fix the PCB board 101 on the operating table). The first position area is the range that can be identified by the high-power microscope. Since the field of view of the high-power microscope is relatively small, the PCB board 101 is initially positioned by the set of nails to ensure that the high-power microscope can accurately identify the position of the blind hole.

[0050] refer to Figure 3 In a preferred embodiment, the UV laser drilling machine uses a laser power of 2.5±0.2W and a defocus of 2±0.2mm when drilling the exposed area on the protective film 103 (i.e., burning through the protective film 103 to expose the target blind hole points on the copper foil 102 below). The diameter of the exposed area is larger than the diameter of the target points. In this embodiment, the UV laser drilling machine preferably uses a laser power of 2.5W and a defocus of 2mm when drilling the exposed area to prevent damage to the copper foil 102 below when the laser energy burns through the protective film 103. In practice, some errors may occur.

[0051] If the power is too low, the laser energy may not be able to burn through the protective film 103 in one go (especially at a thickness of 40μm), requiring secondary processing, which in turn increases the risk of damage to the copper foil 102 (such as ablation). If the power is too high, excessive ablation may occur, and the laser energy will not only penetrate the protective film 103, but also damage the copper foil 102 underneath, and even affect the adhesion of the protective film 103 in the surrounding area. Therefore, controlling the laser power to around 2.5W (with a possible deviation of around 0.2W) can ensure that the laser energy burns through the protective film 103 in one go, while preventing excessive energy from being transferred to the copper foil 102, thus protecting the surface integrity of the copper foil 102. In addition, the diameter of the exposed area is larger than the diameter of the target point (for example, if the diameter of the blind hole alignment point is 0.5mm, the exposed area can be a circular area of ​​2-3mm). Even if there is a certain deviation in practice, it can ensure that the blind hole alignment point can be completely exposed within the exposed area.

[0052] refer to Figure 4 In a preferred embodiment, in step S3, drilling the blind hole to be processed specifically includes: using a laser drilling machine to perform drilling using a spiral processing path from the inside to the outside. In this embodiment, the use of an inside-to-outside processing path can prevent debris from splashing onto the surface of the copper foil 102 during the drilling process, causing contamination. The so-called inside-to-outside processing path means that during laser drilling, the path of the laser beam starts from the center point of the blind hole and gradually expands outward in a spiral. During this process, debris is continuously pushed to the outside of the hole, while the unprocessed area at the edge of the hole (copper foil 102) is still covered by the protective layer, which can effectively prevent debris from splashing onto the surface of the copper foil 102.

[0053] refer to Figure 4 In a preferred embodiment, the spiral processing path of the laser drilling machine is specifically as follows: the laser beam of the laser drilling machine starts from the center point of the blind hole and performs at least one closed circular path processing along a first radius R1; and starts from the tangent point on the closed circular path and expands outward multiple times along the spiral trajectory; when the spiral trajectory reaches the second radius R2, the end point of the spiral processing path automatically connects to the closed circular path with R2 as the radius.

[0054] Specifically, the spiral processing path is as follows: First, the laser beam starts from the center point of the blind hole and performs at least one complete circular path processing with a fixed radius R1, forming a reference circle at the center of the hole to ensure that the initial ablation area is flat; then, the laser beam starts from the tangent point of the initial circular path and expands outward along the spiral trajectory (similar to the Archimedean spiral). With each circle, the radius of the laser beam gradually increases until it reaches the second radius R2 corresponding to the target aperture. When the spiral trajectory expands to R2, the laser beam automatically connects to a closed circular path with R2 as the radius to complete the last circle of processing. Compared with the discrete concentric circle path processing method used in the prior art, the spiral processing path in the present invention has better continuity during the drilling process and shorter processing time. It can also reduce the number of laser starts and stops, reduce the risk of debris flying due to laser repositioning, further ensure the smoothness of the hole edge, improve the true roundness of the hole shape, and improve the processing quality of the blind hole. The quality of blind holes will directly affect the conductive performance of the circuit board. Blind holes with smooth hole walls and high roundness can ensure the uniformity and continuity of the copper plating layer, reduce resistance, effectively improve the conductivity of the circuit board and increase the product yield of the circuit board.

[0055] refer to Figure 3 In a preferred embodiment, after the protective layer is applied to the surface of the copper foil 102 of the PCB board 101, the protective layer is further subjected to a bubble removal process. This ensures that the protective layer and the surface of the copper foil 102 can be better adhered to each other, and avoids the situation where the protective layer is not properly adhered and air is present.

[0056] In a preferred embodiment, the bubble removal process is performed by rolling or vacuuming, with a rolling pressure of 0.3-0.4 MPa. The rolling pressure is preferably 0.4 MPa. If the pressure is too high, the circuit board may be damaged during the rolling process, while if the pressure is too low, the force may not be sufficient to completely expel the air. In this case, the remaining bubbles will cause the surface of the protective film 103 to be uneven, and the copper foil 102 located below the bubbles may not be tightly covered by the protective film 103. This may cause excessive carbonization when the energy of the subsequent laser drilling machine directly ablates the copper layer, resulting in the accumulation of foreign matter at the edge of the hole.

[0057] In order to have a further understanding and recognition of the technical solution of the present invention, several preferred embodiments are listed and described in further detail.

[0058] Example 1:

[0059] 1) Take a PCB board 101, the copper foil 102 on the surface of the PCB board 101 is thicker than 50 microns, or the copper foil 102 is alloy copper (such as titanium copper).

[0060] 2) Take a protective film 103 (the protective film 103 in this embodiment is a resist film model "HH-200-B" produced by Shenzhen Honghua Electronic Technology Co., Ltd.) with a thickness of 40 microns and a transparency of ≥90%. The shape and size of the protective film 103 are compatible with the PCB board 101;

[0061] 3) A worker applies a protective film 103 to the surface of the copper foil 102 of the PCB board 101;

[0062] 4) Debubbling the protective film 103 by rolling or vacuuming;

[0063] 5) Start the optical detection mechanism (low-power lens / high-power lens) of the UV laser drilling machine to identify the blind hole alignment points on the PCB board 101 through the protective film 103 to determine the positions of the blind hole alignment points;

[0064] 6) The UV laser drilling machine starts emitting laser energy for the first time. The laser energy acts on the protective film 103 and processes the exposed area (the energy burns through the protective film 103 but does not act on the copper foil 102). At this time, the laser power is 2.5W and the defocus distance is 2mm.

[0065] 7) The blind hole alignment point appears in the exposed area;

[0066] 8) The UV laser drilling machine starts to emit laser energy for the second time. The energy acts directly on the blind hole alignment point through the exposed area. At this time, the laser power is 6W and the defocus is 0.

[0067] refer to Figure 4 The laser processing path adopts a spiral processing path from the inside to the outside; the spiral processing path is specifically as follows: the laser beam starts from the center point of the blind hole, and first performs at least one complete circular path processing with a fixed radius R1 to form a reference circle in the center of the hole to ensure that the initial ablation area is flat; after that, the laser beam starts from the tangent point of the initial circular path and expands outward along the spiral trajectory (similar to the Archimedean spiral). With each circle, the radius of the laser beam gradually increases until it reaches the second radius R2 corresponding to the target aperture. When the spiral trajectory expands to R2, the laser beam automatically connects to the closed circular path with R2 as the radius to complete the last circle of processing. At this point, the blind hole drilling operation is completed;

[0068] 9) The drilled PCB board 101 is subjected to a film-tearing process (a worker tears off the protective film 103 from the PCB board 101);

[0069] 10) Perform AOI inspection on blind holes;

[0070] 11) The blind holes are further immersed in a micro-etching solution to remove the remaining residues and foreign matter on the surface of the copper foil 102 .

[0071] Comparative Example 1 (without protective film 103):

[0072] 1) Take a PCB board 101 (the thickness of the copper foil 102 is the same as that in Example 1);

[0073] 2) Start the optical detection mechanism (low-power lens / high-power lens) of the UV laser drilling machine to identify the blind hole alignment points on the PCB board 101 and determine the positions of the blind hole alignment points;

[0074] 3) A UV laser drilling machine emits laser energy (laser parameters are the same as those in Example 1) to directly drill blind hole alignment points on the surface of the copper foil 102 (the drilling processing path is the same as that in Example 1);

[0075] 4) After drilling, the PCB board 101 needs to be soaked in a micro-etching solution (the composition and concentration of the micro-etching solution are the same as those in Example 1) to remove the residue and foreign matter on the surface of the copper foil 102;

[0076] 5) Perform AOI inspection on blind holes.

[0077] Comparative Example 2 (Protective film 103 not applied, different drilling process paths)

[0078] 1) Take a PCB board 101 (the thickness of the copper foil 102 is the same as that in Example 1);

[0079] 2) Start the optical detection mechanism (low-power lens / high-power lens) of the UV laser drilling machine to identify the blind hole alignment points on the PCB board 101 and determine the positions of the blind hole alignment points;

[0080] 2) A UV laser drilling machine emits laser energy (laser parameters are the same as those in Example 1) and directly drills blind hole alignment points on the surface of the copper foil 102 using a processing path of discrete concentric circles from the inside to the outside;

[0081] refer to Figure 5 The specific processing path of discrete concentric circles is as follows: the laser scans the first circle with an initial radius R1. After completing the ablation of this layer, the radius increases to R2 (the next circle) until the target aperture is covered. The center of each circle coincides with the center point of the blind hole, forming a nested concentric circle structure.

[0082] Effect comparison:

[0083] like Figure 1 As shown, Figure 1 When blind hole processing is performed using the method of Comparative Example 1, it can be clearly seen that the area around the blind hole opening is severely blackened after drilling, which requires the circuit board to be immersed in a micro-etching solution for a long time to remove residual foreign matter. At this time, it is also impossible to directly perform AOI inspection on the blind hole, otherwise it will easily be mistakenly identified as a defect by AOI, resulting in unnecessary rework.

[0084] and Figure 2 In blind hole processing using the method of Example 1, it can be clearly seen that the blackening phenomenon around the hole mouth has been effectively improved compared to Comparative Example 1. After the protective film 103 is applied, the slag is blocked by the film layer during the drilling process and cannot splash around the hole mouth. At this time, even if AOI inspection is performed directly, there will be no impact. At the same time, the subsequent micro-etching solution immersion time is shorter, and the effect of removing residual foreign matter on the surface of the copper foil 102 will be significantly better.

[0085] Figure 4 In order to drill blind holes using the laser processing path in this embodiment 1, the continuity during the drilling process is better, the laser beam moves continuously along the spiral line, the residue is continuously carried out by the spiral airflow and adheres to the protective film 103, and will not accumulate at the edge of the hole. The processing time is also shorter, the roundness of the blind hole after processing is higher, the quality of the blind hole is better, and the conductivity and reliability of the circuit board are better.

[0086] Figure 5 In order to drill blind holes using the laser processing path of Comparative Example 2, compared with Example 1, the processing path of Comparative Example 2 requires multiple starts and stops of the laser drilling machine during the drilling process, and the processing path is longer, the processing time is also longer, and the residue is easily accumulated in the annular gap during the drilling process, which is more difficult to clean. In addition, the edges of the blind holes after processing are prone to unevenness, which affects the quality of the blind holes, resulting in reduced reliability of the circuit board and relatively poor conductivity.

[0087] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for processing and manufacturing blind holes in a PCB board, characterized in that: The following steps are involved: S1: Apply a protective film to the copper foil surface of the PCB board, wherein the copper foil is an alloy copper, or the thickness of the copper foil is greater than 70 microns, and the transparency of the protective film is ≥90%; S2: Identify and locate the position of the blind hole to be processed on the PCB board to determine the blind hole alignment point; S30: machining an exposed area on the protective film by a laser drilling machine, wherein the laser drilling machine is a UV laser drilling machine; S31: The exposed area corresponds to the position of the blind hole alignment point, and the UV laser drilling machine can drill the blind hole alignment point through the exposed area; S4: Remove the protective film to obtain a blind hole; S5: Electroplating is performed on the obtained blind holes to form circuit conduction between the various layers of the PCB.

2. The method for manufacturing blind holes in a PCB board according to claim 1, wherein: The protective film is made of a material that does not leave any adhesive residue.

3. The method for manufacturing blind holes of a PCB board according to claim 2, wherein: The protective film has a viscosity lower than 0.5 N / cm and a thickness of 35 μm to 45 μm.

4. The method for manufacturing blind holes of a PCB board according to claim 1, wherein: In step S2, identifying and locating the position of the blind hole specifically includes step S20: obtaining the position of the blind hole through the protective film by the optical detection mechanism of the laser drilling machine; the optical detection mechanism includes a low-power mirror and a high-power mirror, the low-power mirror is used to preliminarily scan the position of the blind hole alignment point to determine the first position area; the high-power mirror is used to accurately locate the position of the blind hole alignment point within the first position area.

5. The method for manufacturing blind holes in a PCB board according to claim 1, wherein: In step S2, identifying and locating the position of the blind hole specifically includes: fixing the PCB board in a first position area on the operating table, obtaining the position of the blind hole through the protective film through the optical detection mechanism of the laser drilling machine, and the optical detection mechanism includes a high-power microscope, which is used to accurately locate the position of the blind hole alignment point in the first position area.

6. The method for manufacturing blind holes of a PCB board according to claim 1, wherein: The laser power of the UV laser drilling machine when processing the exposed area on the protective film is 2.5±0.2W, and the defocus amount is 2±0.2mm; the diameter of the exposed area is larger than the diameter of the blind hole alignment point.

7. The method for manufacturing blind holes in a PCB board according to claim 1, wherein: In step S3 , drilling the blind hole position to be processed specifically includes: drilling the hole using a laser drilling machine in a spiral processing path from inside to outside.

8. The method for manufacturing blind holes of a PCB board according to claim 7, wherein: The spiral processing path of the laser drilling machine is specifically as follows: the laser beam of the laser drilling machine starts from the center point of the blind hole and performs at least one closed circular path processing along a first radius R1; and starts from the tangent point on the closed circular path and expands outward multiple times along the spiral trajectory; when the spiral trajectory reaches the second radius R2, the end point of the spiral processing path automatically connects to the closed circular path with R2 as the radius.

9. The method for manufacturing blind holes of a PCB board according to claim 1, wherein: After the copper foil surface of the PCB board is coated with a protective layer, the method further includes step S10: performing a bubble removal treatment on the protective layer.

10. The method for manufacturing blind holes of a PCB board according to claim 9, wherein: The debubbling process is performed by roller pressing or vacuuming, and the roller pressing pressure is 0.3-0.4 MPa.

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