Carbon oil PCB and manufacturing method thereof

Abstract

The application relates to the technical field of printed circuit board manufacturing, and discloses a carbon oil PCB and a manufacturing method thereof. The manufacturing method of the carbon oil PCB comprises the following steps: providing a substrate, the substrate is provided with a first PAD and a second PAD, and the first PAD and the second PAD are arranged at intervals; a first blind hole is arranged on one side of the first PAD close to the second PAD, and the first blind hole has a first aperture formed on the surface of the first PAD; carbon oil is arranged on the substrate, the carbon oil comprises a first oil part covering the first PAD and a second oil part covering the second PAD, the first oil part and the second oil part are arranged at intervals, and part of the first oil part fills the first blind hole through the first aperture. The carbon oil PCB and the manufacturing method thereof provided by the application are used for improving the problem that, in the related art, when the design interval of carbon oil is small, the risk of micro-short circuit or short circuit caused by carbon oil seepage is high.

Description

Technical Field

[0001] This application relates to the field of printed circuit board manufacturing technology, and in particular to a carbon oil PCB and its manufacturing method. Background Technology

[0002] Carbon-ink PCBs (Printed Circuit Boards) are PCBs with carbon-based conductive ink (hereinafter referred to as carbon ink) screen-printed onto the pads, then baked and cured to form a carbon film conductive pattern. Because carbon ink has excellent wear resistance and corrosion resistance, using carbon film buttons with a certain resistance value to replace expensive gold buttons can significantly reduce PCB manufacturing costs. Therefore, carbon-ink PCBs are widely used in the button module field.

[0003] As the wiring density of carbon-ink PCBs increases towards higher precision, the spacing of the circuit patterns requiring carbon ink printing (called carbon ink pads) is constantly decreasing, and the corresponding carbon ink spacing also decreases. Due to the irregular flow of carbon ink during the printing process (a phenomenon called ink seepage) and printing misalignment, the industry standard for minimum carbon ink design spacing is generally defined as ≥0.5mm. When the carbon ink design spacing is <0.5mm, the risk of micro-short circuits or other defects caused by carbon ink seepage is higher, affecting electrical characteristics. Summary of the Invention

[0004] This application provides a carbon oil PCB and its manufacturing method, which improves the problem of high risk of micro-short circuits or short circuits caused by carbon oil seepage when the carbon oil spacing is small in related technologies.

[0005] In a first aspect, embodiments of this application provide a method for manufacturing a carbon oil PCB, comprising:

[0006] A substrate is provided, the substrate having a first PAD and a second PAD, the first PAD and the second PAD being spaced apart;

[0007] A first blind hole is provided on the side of the first PAD close to the second PAD, and the first blind hole has a first opening formed on the surface of the first PAD;

[0008] Carbon oil is disposed on the substrate. The carbon oil includes a first oil portion covering the first PAD and a second oil portion covering the second PAD. The first oil portion and the second oil portion are disposed at intervals. A portion of the first oil portion fills the first blind hole through the first orifice.

[0009] In some embodiments, a first metal limiting portion is provided inside the substrate, the first metal limiting portion defining the bottom surface of the first blind hole.

[0010] In some embodiments, multiple first blind holes are provided, and the multiple first blind holes are spaced apart along the edge of the first PAD near the second PAD.

[0011] In some embodiments, when a first blind hole is provided on the side of the first PAD near the second PAD, a second blind hole is provided on the side of the second PAD near the first PAD, and the second blind hole has a second opening formed on the surface of the second PAD; when carbon ink is screen printed on the substrate, a portion of the second ink portion fills the second blind hole through the second opening.

[0012] In some embodiments, a second metal limiting portion is provided inside the substrate, the second metal limiting portion defining the bottom surface of the second blind hole.

[0013] In some embodiments, multiple second blind holes are provided, and the multiple second blind holes are spaced apart along the edge of the second PAD near the first PAD.

[0014] In some embodiments, after a first blind hole is formed on the side of the first PAD near the second PAD, and before carbon ink is screen-printed on the substrate, copper plating is performed on the substrate to thicken the first PAD, and an electroplated conductive portion is formed on the inner wall of the first blind hole.

[0015] In some embodiments, after the first blind hole is formed on the side of the first PAD close to the second PAD, and before the substrate is subjected to copper plating to thicken the first PAD, and before the conductive portion is plated on the inner wall of the first blind hole, a basic conductive portion is filled at the bottom of the first blind hole.

[0016] In some embodiments, before screen printing carbon ink on the substrate, a barrier is provided on the substrate, the barrier being located between the first PAD and the second PAD; after applying carbon ink to the substrate, the barrier is removed.

[0017] Secondly, embodiments of this application provide a carbon oil PCB, which is manufactured by the carbon oil PCB manufacturing method described in the first aspect.

[0018] The carbon oil PCB manufacturing method provided in this application has the following advantages: Since a first blind hole is provided on the side of the first PAD close to the second PAD, and the first blind hole has a first opening formed on the surface of the first PAD, when carbon oil is applied to the substrate, the first oil part and the second oil part of the carbon oil can respectively cover the first PAD and the second PAD, and part of the first oil part fills the first blind hole through the first opening. Therefore, it can prevent the first oil part from flowing to the second oil part and sticking to it, and ensure that the first oil part and the second oil part are spaced apart. Thus, when the design spacing between the first oil part and the second oil part is small, it can avoid the risk of oil seepage from the first oil part leading to micro-short circuits or other adverse risks.

[0019] The advantages of the carbon oil PCB provided in this application compared to the prior art can be found in the description of the advantages of the carbon oil PCB manufacturing method provided in this application compared to the prior art, which will not be repeated here. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of carbon oil PCB in related technologies;

[0022] Figure 2 yes Figure 1 A top view of the carbon oil PCB shown;

[0023] Figure 3 yes Figure 2 The diagram shows the pads and carbon oil of a carbon oil PCB.

[0024] Figure 4 yes Figure 1 A schematic diagram of the carbon oil PCB and dry film shown;

[0025] Figure 5 This is a flowchart of a method for manufacturing a carbon oil PCB in one embodiment of this application;

[0026] Figure 6 This is a schematic diagram of the substrate structure in one embodiment of this application;

[0027] Figure 7 yes Figure 6 A partial cross-sectional view of the substrate in the X direction shown.

[0028] Figure 8 yes Figure 6A partial cross-sectional view of the substrate in the Y direction shown;

[0029] Figure 9 yes Figure 6 A schematic diagram of the structure of the first PAD and the second PAD on the substrate shown.

[0030] Figure 10 Yes Figure 7 A schematic diagram of the substrate after copper plating.

[0031] Figure 11 This is a schematic diagram of the substrate after copper plating in another embodiment of this application;

[0032] Figure 12 yes Figure 10 A partial cross-sectional view of another part of the substrate shown;

[0033] Figure 13 Is Figure 12 A schematic diagram showing the substrate after carbon oil has been applied.

[0034] Figure 14 This is a schematic diagram of carbon oil being applied to a substrate in another embodiment of this application;

[0035] Figure 15 yes Figure 14 A top view of the substrate and carbon oil shown;

[0036] Figure 16 This is a schematic diagram of carbon oil being applied to a substrate in another embodiment of this application.

[0037] The markings in the diagram mean:

[0038] 1. Carbon oil PCB; 2. Carbon oil PAD; 3. Carbon oil; 4. Dry film;

[0039] 100. Substrate;

[0040] 10. First PAD; 11. First blind via; 111. Electroplated conductive part; 112. Basic conductive part;

[0041] 20. Second PAD; 21. Second blind hole;

[0042] 30. First metal limiting part;

[0043] 40. Second metal limiting part;

[0044] 50. Solder resist layer;

[0045] 60. Carbon oil; 61. First oil section; 62. Second oil section;

[0046] 70. Barrier components. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0048] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0049] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0050] In this specification, references to "one embodiment," "some embodiments," or simply "embodiment" mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. Furthermore, in one or more embodiments, specific features, structures, or characteristics may be combined in any suitable manner.

[0051] To illustrate the technical solution of this application, the following description is provided in conjunction with specific accompanying drawings and embodiments.

[0052] Carbon-based PCBs refer to PCBs with carbon-based conductive ink (hereinafter referred to as carbon ink) screen-printed onto the pads, then baked and cured to form a carbon film conductive pattern. Because carbon ink has excellent wear resistance and corrosion resistance, using carbon film buttons with a certain resistance value to replace expensive gold buttons can significantly reduce PCB manufacturing costs. Therefore, carbon-based PCBs are widely used in the button module field.

[0053] Please refer to Figure 1 and Figure 2 As the wiring density of carbon ink PCB1 develops towards higher precision, the spacing design of the circuit patterns requiring carbon ink 3 silkscreen (referred to as carbon ink PAD2) is also continuously decreasing, and the corresponding spacing of the carbon ink 3 silkscreen also decreases accordingly. Please refer to the following: Figure 3 Due to the irregular flow of carbon ink 3 during the screen printing process (this phenomenon is called ink seepage) and screen printing alignment deviation, the industry generally defines the minimum design spacing H of carbon ink 3 as ≥0.5mm. When the minimum design spacing H of carbon ink 3 is <0.5mm, the risk of micro-short circuit failure caused by carbon ink 3 seepage is high, affecting electrical characteristics.

[0054] Please refer to Figure 4 In related technologies, considering the alignment deviation of screen printing and the influence of carbon ink 3 seepage, for carbon ink PCBs with a minimum design spacing H < 0.5mm, a pattern transfer process (dry film 4 / wet film coating, exposure & development) is generally added before screen printing carbon ink 3. The purpose is to retain dry film 4 or wet film between adjacent carbon ink PADs 2. Then, carbon ink 3 is screen printed on the carbon ink PADs 2, and after baking and curing, the dry film 4 or wet film is removed through a stripping process. Placing dry film 4 or wet film between carbon ink PADs 2 blocks the flow of carbon ink 3 to prevent short circuits. In actual production, due to the certain fluctuation of carbon ink 3 seepage (generally about 0.15mm-0.2mm), it is inevitable that carbon ink 3 will seep to the side of the dry film 4 or wet film and stick during screen printing. This leads to incomplete stripping at the sticking points during stripping, and the larger the sticking area, the higher the risk of incomplete stripping. In addition, while the carbon oil 3 is baked and cured at high temperature, the dry film 4 or wet film is also heat-cured. This process usually results in incomplete film removal, and the alkaline stripping solution is somewhat aggressive to the surface of the carbon oil 3, which has an adverse effect on the wear resistance of the carbon oil 3. Therefore, this method has limitations.

[0055] In view of this, this application provides a carbon oil PCB and its manufacturing method. Since a first blind hole is provided on the side of the first PAD near the second PAD, and the first blind hole has a first opening formed on the surface of the first PAD, when carbon oil is applied to the substrate, the first oil part and the second oil part of the carbon oil can respectively cover the first PAD and the second PAD, and part of the first oil part fills the first blind hole through the first opening. Therefore, it can prevent the first oil part from flowing to the second oil part and sticking to it, and ensure that the first oil part and the second oil part are spaced apart. Thus, when the design spacing between the first oil part and the second oil part is small, it can avoid the risk of oil seepage from the first oil part causing micro-short circuits or other adverse risks.

[0056] Please refer to Figures 5 to 13 In a first aspect, embodiments of this application provide a method for manufacturing a carbon oil PCB, comprising:

[0057] S100: A substrate 100 is provided, wherein a first PAD 10 and a second PAD 20 are provided, and the first PAD 10 and the second PAD 20 are spaced apart.

[0058] Specifically, both the first PAD10 and the second PAD20 are carbon-based PADs. Multiple first PAD10s and multiple second PAD20s can be configured, with each corresponding to the previous one. The substrate 100 normally completes processes such as material cutting, inner layer circuitry, lamination, and edge milling.

[0059] For example, both the first PAD10 and the second PAD20 are rectangular PADs of 1000μm*1200μm, and the spacing between adjacent first PAD10s and adjacent second PAD20s is 500μm.

[0060] S200: A first blind hole 11 is provided on the side of the first PAD10 near the second PAD20. The first blind hole 11 has a first opening formed on the surface of the first PAD10.

[0061] Specifically, a first blind hole 11 can be provided on the side of the first PAD 10 near the second PAD 20 by laser drilling or mechanical drilling. One or more first blind holes 11 can be provided. Before laser drilling, the substrate 100 can undergo a pre-laser browning process.

[0062] The aperture D of the first blind hole 11 can be designed to be between 100μm and 250μm. The distance S (usually referred to as the blind hole ring) of the first blind hole 11 from the edge of the first PAD 10 in the X and Y directions can be designed to be 50μm. The distance L between the holes of two adjacent first blind holes 11 can be designed to be between 50μm and 100μm. According to the above design rules, a certain number of first blind holes 11 are designed at the edge positions of the adjacent sides of the first blind hole 11 and the second blind hole 21 (the actual number of first blind holes 11 depends on the aperture and spacing of the first blind holes 11 and the width of the first PAD 10 in the Y direction).

[0063] Laser drilling is performed from the surface layer where the first PAD 10 is designed to the second outermost layer of the substrate 100 to form a first blind hole 11, with the bottom of the first blind hole 11 located on the second outermost layer. After the first blind hole 11 is set on the side of the first PAD 10 close to the second PAD 20, the mechanical drilling, copper plating, and full-board electroplating processes of the substrate 100 are completed normally to meet the requirements for through-hole copper and surface copper.

[0064] Laser drilling can be performed using a CO2 laser drilling machine. The laser parameters are set according to the parameters defined in the work instruction for the corresponding hole diameter and thickness. In this embodiment, the main laser processing parameters are as follows: energy 15mJ, pulse count 1 / 3 / 2 shots, and pulse width 15 / 8 / 5μs. After laser drilling, the diameter of the first blind hole 11 is measured, with a tolerance control of ±10μm.

[0065] S300: Carbon oil 60 is provided on substrate 100. Carbon oil 60 includes a first oil portion 61 covering a first PAD 10 and a second oil portion 62 covering a second PAD 20. The first oil portion 61 and the second oil portion 62 are provided at intervals. A portion of the first oil portion 61 fills the first blind hole 11 through the first orifice.

[0066] Specifically, carbon ink 60 can be applied to the substrate 100 using a screen printing method. The first blind hole 11 serves to accommodate the carbon ink 60 and reduce the amount of carbon ink 60 seeping through.

[0067] Since part of the first oil portion 61 fills the first blind hole 11 through the first orifice, it can prevent the first oil portion 61 from moving towards the second oil portion 62 and sticking to the second oil portion 62, thus ensuring that the first oil portion 61 and the second oil portion 62 are spaced apart.

[0068] As can be seen from the above, the method for manufacturing a carbon oil PCB provided in this application embodiment has a first blind hole 11 provided on the side of the first PAD10 near the second PAD20. The first blind hole 11 has a first opening formed on the surface of the first PAD10. Therefore, when carbon oil 60 is provided on the substrate 100, the first oil portion 61 and the second oil portion 62 of the carbon oil 60 can cover the first PAD10 and the second PAD20 respectively. Furthermore, part of the first oil portion 61 fills the first blind hole 11 through the first opening. This can prevent the first oil portion 61 from flowing to the second oil portion 62 and sticking to it, ensuring that the first oil portion 61 and the second oil portion 62 are spaced apart. Thus, when the design spacing between the first oil portion 61 and the second oil portion 62 is small, the risk of oil leakage from the first oil portion 61 leading to micro-short circuits or other adverse effects can be avoided.

[0069] In this embodiment, a first metal limiting part 30 is provided inside the substrate 100, and the first metal limiting part 30 defines the bottom surface of the first blind hole 11.

[0070] By adopting the above solution, when the first blind hole 11 is set on the side of the first PAD10 close to the second PAD20, the bottom surface of the first blind hole 11 can be defined by the first metal limiting part 30, thereby making it easier to control the depth of the first blind hole 11, making it easier to position the drilling, and avoiding drilling crookedly or too deeply.

[0071] It should be noted that the first metal limiting part 30 can be a copper pad. The first metal limiting part 30 can be an independent PAD (called a blind hole bottom PAD) disposed at a corresponding position on the second outermost layer of the substrate 100. Taking a four-layer board with the first PAD 10 designed on the L1 layer of the substrate 100 as an example, the second outermost layer is the L2 layer of the substrate 100. To prevent the first blind hole 11 from being misaligned, the size D1 of the second outermost layer blind hole bottom PAD is 100μm larger than the hole diameter D of the first blind hole 11. The depth of the first blind hole 11 is the dielectric thickness A of the L1 layer to the L2 layer plus the thickness of the L1 layer (the thickness of the L1 layer is approximately 8μm). To facilitate laser drilling and electroplating, the dielectric thickness A corresponding to the first blind hole 11 is preferably designed to be between 50μm and 250μm. After laser drilling, the first blind hole 11 was inspected by AOI (Automated Optical Inspection) equipment and found to fall on the bottom PAD of the second outermost blind hole, with no misalignment defects outside the bottom PAD of the blind hole.

[0072] Optionally, multiple first blind holes 11 are provided, and the multiple first blind holes 11 are spaced apart along the edge of the first PAD 10 near the second PAD 20.

[0073] This arrangement better prevents the first oil section 61 from moving closer to the second oil section 62 and sticking to it, ensuring that the first oil section 61 and the second oil section 62 are spaced apart.

[0074] Understandably, each first blind hole 11 is partially filled with the first oil portion 61. The first metal limiting portion 30 can be configured to correspond one-to-one with the first blind hole 11.

[0075] For example, the first PAD10 and the second PAD20 are spaced apart along a first direction, which can be... Figure 6 In the X direction, multiple first blind holes 11 are spaced apart along the second direction, which can be... Figure 6 In the Y direction, the second direction is perpendicular to the first direction.

[0076] Please refer to Figures 5 to 13 In this embodiment, when a first blind hole 11 is provided on the side of the first PAD10 near the second PAD20, a second blind hole 21 is provided on the side of the second PAD20 near the first PAD10. The second blind hole 21 has a second opening formed on the surface of the second PAD20. When carbon ink 60 is screen printed on the substrate 100, a portion of the second ink portion 62 fills the second blind hole 21 through the second opening.

[0077] By adopting the above solution, when carbon oil 60 is provided on the substrate 100, part of the second oil portion 62 fills the second blind hole 21 through the second orifice. Therefore, it is possible to prevent the second oil portion 62 from flowing to stick to the first oil portion 61, ensuring that the first oil portion 61 and the second oil portion 62 are spaced apart. Thus, when the design spacing between the first oil portion 61 and the second oil portion 62 is small, it is possible to avoid adverse risks such as oil seepage from the second oil portion 62 leading to micro-short circuits or short circuits.

[0078] The substrate 100 has a second metal limiting part 40 inside, which defines the bottom surface of the second blind hole 21.

[0079] By adopting the above solution, when the second blind hole 21 is set on the side of the second PAD20 close to the first PAD10, the bottom surface of the second blind hole 21 can be defined by the second metal limiting part 40, thereby making it easier to control the depth of the second blind hole 21, making it easier to position the drilling, and avoiding drilling crookedly or too deeply.

[0080] It should be noted that the second metal limiting part 40 can be a copper pad.

[0081] Optionally, multiple second blind holes 21 are provided, and the multiple second blind holes 21 are spaced apart along the edge of the second PAD 20 near the first PAD 10.

[0082] This configuration better prevents the second oil section 62 from moving closer to the first oil section 61 and sticking to it, ensuring that the first oil section 61 and the second oil section 62 are spaced apart.

[0083] Understandably, each second blind hole 21 is partially filled with the second oil portion 62. The second metal limiting portion 40 can be provided in a one-to-one correspondence with the second blind hole 21.

[0084] For example, a plurality of second blind holes 21 are spaced apart along a second direction.

[0085] Please refer to Figures 5 to 13 In some embodiments, after the first blind hole 11 is provided on the side of the first PAD 10 near the second PAD 20 and before the carbon ink 60 is screen-printed on the substrate 100, the substrate 100 is plated with copper to thicken the first PAD 10, and a plated conductive portion 111 is provided on the inner wall of the first blind hole 11.

[0086] By adopting the above solution, the thickness of the first PAD10 can meet the usage requirements.

[0087] It is understandable that the first blind hole 11 is used to accommodate the first oil part 61. Generally, there are no requirements on the thickness of the electroplated conductive part 111. After the copper plating process, the electroplated conductive part 111 is provided on the inner wall of the first blind hole 11. As a result, the effective aperture of the first blind hole 11 becomes smaller and the effective depth becomes shallower.

[0088] When the dielectric thickness A of the first blind hole 11 is less than 125 μm and the drilling diameter of the first blind hole 11 is 100-250 μm, the effective diameter and effective depth of the first blind hole 11 are reduced by about 20 μm-30 μm after the conventional full-board electroplating process. Under this condition, the first blind hole 11 can be filled by the first oil part 61 when the carbon ink 60 is screen printed.

[0089] When the dielectric thickness A of the first blind hole 11 is ≤250μm and the drilling diameter of the first blind hole 11 is 100-250μm, due to the relatively thick dielectric thickness A of the first blind hole 11, the conventional full-board electroplating solution has a weak ability to plate the first blind hole 11 deeply. The amount of copper plated on the bottom and wall of the first blind hole 11 is small. After electroplating, the hole diameter and depth of the first blind hole 11 change very little. When the carbon ink 60 is screen printed in the future, the first blind hole 11 at the edge of the first PAD10 has a situation where the first ink part 61 is not fully filled, resulting in poor copper exposure.

[0090] To solve the above problems, optionally, after the first blind hole 11 is provided on the side of the first PAD10 close to the second PAD20, and the substrate 100 is subjected to copper plating to thicken the first PAD10, and before the conductive part 111 is provided on the inner wall of the first blind hole 11, the bottom of the first blind hole 11 is filled with a basic conductive part 112.

[0091] This design avoids the situation where the thickness of the electroplated conductive part 111 inside the first blind hole 11 is insufficient to meet the design requirements due to the first blind hole 11 being too deep, which would cause the first blind hole 11 to contain too much first oil part 61, resulting in the edge part of the first PAD 10 not being covered by the first oil part 61 and forming a poor copper exposure.

[0092] It should be noted that when the dielectric thickness A of the first blind via 11 is ≤250μm (125μm≤), a blind via filling process can be added before electroplating the substrate 100 to fill the bottom of the first blind via 11 with a base conductive portion 112. The corresponding process design is: copper plating, blind via filling, and full-board electroplating. Utilizing the characteristics of the filling solution (the copper deposition rate inside the first blind via 11 is higher than that on the surface of the substrate 100), and by adjusting the filling electroplating parameters (such as shortening the filling electroplating time from the conventional 60min-80min to 30min-40min), the first blind via 11 is partially filled (the bottom of the first blind via 11 is filled with a base conductive portion 112), that is, the thickness of the base conductive portion 112 is approximately half the dielectric thickness A of the first blind via 11. After completing the blind via filling process, the full-board electroplating process (copper plating on the substrate 100) is then performed. It has been verified that after the first blind hole 11 is filled by electroplating and full board electroplating, the first blind hole 11 can be filled by carbon ink 60 when screen printing carbon ink 60, and there are no depressions or copper exposure defects on the surface.

[0093] It is understandable that when performing copper plating on the substrate 100, the second PAD 20 can be thickened, and a plated conductive portion 111 can be provided on the inner wall of the second blind hole 21; when filling the bottom of the first blind hole 11 with the basic conductive portion 112, the bottom of the second blind hole 21 is filled with the basic conductive portion 112, which is similar to the operation method of the first blind hole 11.

[0094] Optionally, after copper plating is performed on the substrate 100, the outer layer circuitry of the substrate 100 can be fabricated (including film lamination, exposure, development, etching, and film removal processes), resulting in a first PAD 10 and a second PAD 20 with a first blind via 11 and a second blind via 21 on the surface of the substrate 100. Subsequently, a solder resist process is performed to form a solder resist layer 50. Typically, both the first PAD 10 and the second PAD 20 have a solder resist window design, and no solder resist bridges are designed between the first PAD 10 and the second PAD 20.

[0095] Please refer to Figure 14 and Figure 15 In some embodiments, before the carbon ink 60 is screen-printed on the substrate 100, a barrier 70 is provided on the substrate 100, the barrier 70 being located between the first PAD 10 and the second PAD 20; after the carbon ink 60 is provided on the substrate 100, the barrier 70 is removed.

[0096] By adopting the above solution, the barrier 70 can be used to block the carbon oil 60 from seeping in, while the first blind hole 11 and the second blind hole 21 can accommodate the carbon oil 60, reduce the amount of seepage, and prevent the carbon oil 60 from being excessively adhered to the side of the barrier 70, so that the barrier 70 can be removed after the carbon oil 60 is installed.

[0097] The barrier element 70 can be a high-temperature tape, which is produced by laser cutting. The substrate 100 is first cleaned using an outer layer pre-processing line, along with the surfaces of the first PAD 10 and the second PAD 20 (to improve the adhesion between the carbon ink 60 and the first PAD 10 and the second PAD 20). Then, a vacuum laminator is used to apply the high-temperature tape to the entire board on the side where carbon ink 60 needs to be screen-printed. Its shape is achieved by a subsequent laser cutting process to prevent short circuits caused by carbon ink 60 leakage. The selected high-temperature tape thickness T1 is equal to the theoretical sum of the first PAD 10 thickness and the carbon ink 60 thickness T. For example, if the theoretical first PAD 10 thickness (copper thickness) is 35 μm and the carbon ink 60 thickness is 15 μm, the sum is 50 μm, and therefore the high-temperature tape thickness is 50 μm. To ensure that the high-temperature tape is filled between the first PAD10 and the second PAD20 and firmly adhered to the surface of the substrate 100, a vacuum lamination device is used for lamination. The main processing parameters for vacuum lamination are as follows: lamination pressure is 4.5±0.5 kg / cm2, pressure application time is 40±5 s, vacuum degree is ≤1 Torr, and vacuum protection time is 40±5 s.

[0098] After applying high-temperature tape to the entire board, a UV (Ultraviolet) laser cutting device is used to laser cut the high-temperature tape between the first PAD10 and the second PAD20 to obtain the required high-temperature tape shape. A certain width of high-temperature tape is retained on the surface of the substrate 100 between the first PAD10 and the second PAD20 to form a barrier 70. The designed width of the high-temperature tape retained between the first PAD10 and the second PAD20 is equal to the minimum designed spacing N of carbon ink 60 after screen printing, N = K - 2 * Tmax, where K is the designed spacing of the ink area under the first PAD10 and the second PAD20, and Tmax is the maximum value of the theoretical ink penetration amount T of carbon ink 60, to prevent carbon ink 60 short circuit abnormality when the actual ink penetration amount exceeds the theoretical ink penetration amount during subsequent screen printing of carbon ink 60.

[0099] To improve the positional accuracy of the laser-cut tape relative to the first PAD10 and the second PAD20, pre-defined shapes (such as round or square PADs) are gripped at the four corners of the substrate 100 for alignment during laser cutting. The laser cutting parameters are set according to the thickness of the high-temperature tape used. After cutting, the high-temperature tape should be precisely etched through. After the laser etches through the high-temperature tape, it slightly touches the surface of the substrate 100, forming an acceptable indentation of approximately 5 μm on the surface of the substrate 100 along the path of the cut high-temperature tape. After laser cutting, the high-temperature tape adhered to the substrate 100 is lifted and peeled off along the corners. The high-temperature tape not between the first PAD10 and the second PAD20 is removed, leaving a high-temperature tape of width N between the first PAD10 and the second PAD20.

[0100] By utilizing the high-temperature resistance of high-temperature tape, the problems of incomplete film removal and reduced wear resistance of carbon ink 60 caused by oil leakage and short circuit in screen printing carbon ink 60 technology can be solved, enabling the production of small-pitch carbon ink 60 products (minimum design pitch of carbon ink 60 < 0.5mm).

[0101] After completing the laser cutting process and removing the high-temperature tape between the first PAD10 and the second PAD20, carbon ink 60 is screen-printed onto the first PAD10 and the second PAD20 using a screen printing process.

[0102] When designing the screen printing stencil, to avoid screen printing misalignment leading to poor copper exposure in the first PAD10 and the second PAD20, the ink under the carbon ink 60 is 0.15mm larger on each side than the first PAD10 and the second PAD20. During the screen printing of carbon ink 60, irregular ink seepage occurs. For a conventional carbon ink 60 PAD (without blind holes at the edges), the amount of carbon ink 60 seepage T is approximately 0.15mm-0.2mm. When the designed spacing K between the ink under the carbon ink 60 of adjacent carbon ink 60 PADs is less than 0.5mm, the theoretical minimum spacing N of the finished carbon ink 60 after screen printing is less than 0.1mm (N = K - 2 * Tmax = 0.5 - 2 * 0.2mm = 0.1mm, where Tmax is the theoretical maximum value of the amount of carbon ink 60 seepage T, 0.2mm, and the finished carbon ink 60 spacing of 0.1mm is usually considered the limit spacing). Considering the alignment deviation and the fluctuation of carbon ink 60 seepage, this design has the risk of carbon ink 60 bridging and short circuit in actual production.

[0103] Therefore, for circuit boards with a carbon ink 60 spacing K < 0.5mm, high-temperature tape is laid between the first PAD10 and the second PAD20 to prevent carbon ink 60 from seeping in. At the same time, first blind holes 11 and second blind holes 21 are pre-set on the edges of the first PAD10 and the second PAD20 respectively to accommodate carbon ink 60, thereby reducing the amount of seepage and preventing excessive adhesion between carbon ink 60 and the side of the high-temperature tape, so that the high-temperature tape can be removed after screen printing carbon ink 60.

[0104] The screen printing ink 60 uses a stencil made of 77T composite steel wire mesh and 50μm water film. The composite steel wire mesh is woven from stainless steel wire and polyester wire, offering higher screen printing accuracy and stability compared to traditional steel or polyester mesh. During production, after each substrate 100 is screen-printed, the bottom of the stencil must be wiped with a lint-free cloth to remove any residual ink before printing the next substrate 100. This prevents the accumulation of residual ink on the bottom of the stencil, which could lead to a sudden increase in ink penetration during subsequent screen printing processes and cause a short circuit in the ink 60.

[0105] Using this process, the amount of oil seepage T of the first PAD10 and the second PAD20, which include the first blind hole 11 and the second blind hole 21, can be stably controlled within 0.05mm, reducing the oil seepage by more than half compared to related technologies. Simultaneously, by adding high-temperature tape between the first PAD10 and the second PAD20 to block oil seepage, short-circuit anomalies in the carbon ink 60 are prevented when the actual oil seepage exceeds the theoretical oil seepage during screen printing. While ensuring that the finished carbon ink 60 spacing N ≥ 0.1mm, this embodiment can achieve a carbon ink 60 design spacing K of 0.2mm (K = N + 2 * Tmax = 0.1 + 2 * 0.05). After screen printing the carbon ink 60, it is cured by baking in a vertical oven at 150℃ for 60 minutes.

[0106] After the PCB is screen-printed with carbon ink 60, the high-temperature tape can be effectively removed using specialized equipment (including vacuum suction cups) or tools (vacuum suction tubes, etc.) without leaving any residue. Subsequent processes such as molding, electrical testing, surface treatment, FQC (Final Quality Control, outgoing inspection) and packaging can then proceed as normal.

[0107] The carbon ink PCB manufacturing method provided in this application embodiment does not require film removal after screen printing carbon ink 60, thus avoiding the problems of incomplete film removal and reduced wear resistance of carbon ink 60 caused by film removal in the prior art, and can realize the manufacturing of small-pitch carbon ink PCB.

[0108] Please refer to Figure 16 In some embodiments, the substrate 100 is further provided with metallized through-holes.

[0109] Secondly, embodiments of this application provide a carbon oil PCB, which is manufactured by the carbon oil PCB manufacturing method of the first aspect.

[0110] The carbon oil PCB provided in this application embodiment has a first blind hole 11 on the side of the first PAD10 near the second PAD20. The first blind hole 11 has a first opening formed on the surface of the first PAD10. Therefore, when carbon oil 60 is applied to the substrate 100, the first oil portion 61 and the second oil portion 62 of the carbon oil 60 can cover the first PAD10 and the second PAD20 respectively. Furthermore, part of the first oil portion 61 fills the first blind hole 11 through the first opening. This can prevent the first oil portion 61 from flowing to the second oil portion 62 and sticking to it. This ensures that the first oil portion 61 and the second oil portion 62 are spaced apart. Thus, when the design spacing between the first oil portion 61 and the second oil portion 62 is small, it avoids the risk of oil seepage from the first oil portion 61 leading to micro-short circuits or other adverse effects.

[0111] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for manufacturing a carbon oil PCB, characterized in that, include: A substrate is provided, the substrate having a first PAD and a second PAD, the first PAD and the second PAD being spaced apart; A first blind hole is provided on the side of the first PAD close to the second PAD, and the first blind hole has a first opening formed on the surface of the first PAD; Carbon oil is applied to the substrate. The carbon oil includes a first oil portion covering the first PAD and a second oil portion covering the second PAD. The first oil portion and the second oil portion are spaced apart. A portion of the first oil portion fills the first blind hole through the first orifice to prevent the first oil portion from moving towards the second oil portion and sticking to it.

2. The method for manufacturing a carbon oil PCB according to claim 1, characterized in that, The substrate has a first metal limiting part inside, which defines the bottom surface of the first blind hole.

3. The method for manufacturing a carbon oil PCB according to claim 1, characterized in that, Multiple first blind holes are provided, and the multiple first blind holes are spaced apart along the edge of the first PAD near the second PAD.

4. The method for manufacturing a carbon oil PCB according to claim 1, characterized in that, When a first blind hole is provided on the side of the first PAD near the second PAD, a second blind hole is provided on the side of the second PAD near the first PAD, and the second blind hole has a second opening formed on the surface of the second PAD; when carbon ink is screen printed on the substrate, a portion of the second ink portion fills the second blind hole through the second opening.

5. The method for manufacturing a carbon oil PCB according to claim 4, characterized in that, The substrate has a second metal limiting part inside, which defines the bottom surface of the second blind hole.

6. The method for manufacturing a carbon oil PCB according to claim 4, characterized in that, Multiple second blind holes are provided, and the multiple second blind holes are spaced apart along the edge of the second PAD near the first PAD.

7. The method for manufacturing a carbon oil PCB according to any one of claims 1 to 6, characterized in that, After a first blind hole is formed on the side of the first PAD close to the second PAD, and before carbon ink is screen-printed on the substrate, copper plating is performed on the substrate to thicken the first PAD, and an electroplated conductive part is formed on the inner wall of the first blind hole.

8. The method for manufacturing a carbon oil PCB according to claim 7, characterized in that, After the first blind hole is formed on the side of the first PAD close to the second PAD, and before the substrate is subjected to copper plating to thicken the first PAD, and before the conductive portion is plated on the inner wall of the first blind hole, a basic conductive portion is filled at the bottom of the first blind hole.

9. The method for manufacturing a carbon oil PCB according to any one of claims 1 to 6, characterized in that, Before screen printing carbon ink on the substrate, a barrier is provided on the substrate, the barrier being located between the first PAD and the second PAD; after applying carbon ink to the substrate, the barrier is removed.

10. A carbon oil PCB, characterized in that, The PCB is manufactured by the method for producing a carbon oil PCB as described in any one of claims 1 to 9.

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