Manufacturing method of PCB with step-shaped impedance Cobang

Abstract

The invention discloses a manufacturing method of a PCB (Printed Circuit Board) with step-shaped impedance Kebang. The manufacturing method comprises the process steps of material preparation, adhesive tape pasting, adhesive tape waste edge cutting, PP (Propene Polymer) groove milling, pressing, drilling, electroplating, depth-controlled milling, adhesive tape tearing and the like. According to the manufacturing method of the PCB with the step-shaped impedance Kebang, the waste area above the impedance line is selectively removed through the process of combining depth-controlled milling and high-temperature adhesive tape protection, and the step-shaped impedance Kebang structure is formed, so that interference of the waste area on impedance is greatly reduced, the accuracy of impedance value judgment is improved, and the reliability of the PCB is improved. The method is especially suitable for a high-precision impedance control scene of a high-end high-speed PCB, and provides a reliable guarantee for the integrity of high-frequency signal transmission.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of PCB impedance coplanar technology, and in particular to a manufacturing method of a PCB board with a stepped impedance coplanar structure. BACKGROUND

[0002] In the impedance control design of high-end high-speed printed circuit boards (PCB), impedance control is one of the core technical indicators to ensure signal transmission integrity, and the design rationality and process reliability of the impedance coplanar structure, which is the key structure to achieve precise impedance control, directly determine the high-frequency signal transmission performance of the PCB board. With the development of electronic devices towards high speed, miniaturization and high integration, the precision requirement of the PCB board impedance is increasingly stringent, and small deviations in impedance values may cause signal reflection, attenuation or crosstalk, thereby affecting the stability and efficiency of the entire electronic system.

[0003] In the prior art, the manufacturing of the impedance coplanar structure usually adopts a full-layer pressing process, that is, the inner layer substrate containing the impedance line and other functional layers are directly pressed into a whole structure by prepreg (PP), without setting a targeted isolation or avoidance structure above the impedance layer. However, this traditional full-layer pressing process of the impedance coplanar structure has obvious defects: the prepreg area above the impedance line is equivalent to an electromagnetic interference source near the impedance line, which will form parasitic capacitance, inductance and other non-ideal parameters between the impedance line and the prepreg area, interfere with the signal transmission path and electromagnetic field distribution, and cause deviations between the actual measurement results and the design target of the impedance value, affecting the accurate determination of the impedance characteristics. Especially in the high-speed signal transmission scenario, this interference may cause the signal integrity to decline, which cannot meet the requirements of high-end electronic devices for signal transmission quality. SUMMARY

[0004] In order to overcome the problem that the impedance coplanar structure in the prior art adopts full-layer pressing and does not form a step, resulting in interference of the impedance line by the prepreg area above the impedance line and affecting the determination of the impedance value, the present application provides a manufacturing method of a PCB board with a stepped impedance coplanar structure, which selectively removes the prepreg area above the impedance line by combining the controlled-depth milling and high-temperature adhesive tape protection processes, forms a stepped impedance coplanar structure, and thus greatly reduces the interference of the prepreg area on the impedance and improves the accuracy of the determination of the impedance value.

[0005] The technical solution of the present application is as follows:

[0006] A manufacturing method of a PCB board with a stepped impedance coplanar structure, comprising:

[0007] Preparation: prepare an upper sub-board and an impedance coplanar structure lower sub-board, and the impedance coplanar structure region of the impedance coplanar structure lower sub-board is provided with an impedance line on the top surface;

[0008] Tape pasting: high temperature tape is pasted on the impedance coban area, all the head ends of the impedance lines are exposed from the high temperature tape, and the remaining part is covered by the high temperature tape;

[0009] Tape waste edge cutting: the waste edge of the high temperature tape is cut;

[0010] PP milling: the area corresponding to the high temperature tape on the PP layer at the bottom of the upper sub-plate is milled to form a tape accommodating groove;

[0011] Pressing: the upper sub-plate after milling and the impedance coban lower sub-plate after tape pasting are pressed to form a whole plate;

[0012] Drilling and electroplating: through holes are drilled on the whole plate, and the through holes are electroplated to be conductive, and each through hole corresponds to the head end of one impedance line;

[0013] Depth control milling and tape tearing: the corresponding waste area above the high temperature tape in the whole plate is removed by a mechanical depth control milling machine, and the high temperature tape is torn off to obtain a PCB plate with a stepped impedance coban.

[0014] According to the manufacturing method of the PCB plate with the stepped impedance coban, the distance between the high temperature tape after cutting and the head end of the impedance line is not less than 2mm.

[0015] According to the manufacturing method of the PCB plate with the stepped impedance coban, the width of the high temperature tape after cutting is the same as the width of the impedance coban area.

[0016] According to the manufacturing method of the PCB plate with the stepped impedance coban, the thickness of the high temperature tape is 60-80mm.

[0017] According to the manufacturing method of the PCB plate with the stepped impedance coban, the thickness of the high temperature tape is the same as the depth of the tape accommodating groove.

[0018] According to the manufacturing method of the PCB plate with the stepped impedance coban, the length and width of the tape accommodating groove are larger than the length and width of the high temperature tape after cutting.

[0019] According to the manufacturing method of the PCB plate with the stepped impedance coban, the length and width of the tape accommodating groove are larger than the length and width of the high temperature tape after cutting by 3-8mil.

[0020] According to the manufacturing method of the PCB plate with the stepped impedance stub according to the scheme, the waste area thickness is the same as the thickness of the upper sub-plate, and the length and width of the waste area are greater than the length and width of the high-temperature adhesive tape after cutting.

[0021] According to the manufacturing method of the PCB plate with the stepped impedance stub according to the scheme, the length and width of the waste area are greater than the length and width of the high-temperature adhesive tape after cutting by 4-8 mil.

[0022] According to the manufacturing method of the PCB plate with the stepped impedance stub according to the scheme, in the adhesive tape waste edge cutting step, a CO2 laser drilling machine is used to cut the waste edge of the high-temperature adhesive tape, the spot diameter of the CO2 laser drilling machine is 4-8 mil, and the cutting interval is 1-3 mil.

[0023] Compared with the prior art, the beneficial effects of the present application are that:

[0024] The manufacturing method of the PCB plate with the stepped impedance stub according to the present application selectively removes the waste area above the impedance line through processes such as material preparation, adhesive tape sticking, adhesive tape waste edge cutting, PP slot milling, pressing, drilling, electroplating, depth control milling, and adhesive tape tearing, to form a stepped impedance stub structure, thereby greatly reducing the interference of the waste area on the impedance, improving the accuracy of impedance value determination, and being especially suitable for high-precision impedance control scenarios of high-end high-speed PCBs, and providing reliable protection for the integrity of high-frequency signal transmission. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0026] Figure 1 The flow chart of the manufacturing method of the PCB plate with the stepped impedance stub according to an embodiment of the present application;

[0027] Figure 2 The structural schematic diagram of the PCB plate with the stepped impedance stub according to an embodiment of the present application.

[0028] In the drawings,

[0029] 1, upper sub-plate; 2, impedance stub lower sub-plate; 3, impedance line; 4, via hole. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it need not be further defined and explained in subsequent drawings. It is also declared that the following described embodiments are only for explaining the present application and not for limiting the present application.

[0031] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification and claims of the present application are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product or device. The terms "mounting", "setting", "connecting", "fixing" and the like should be interpreted broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly used when the product of the application is used, or the orientation or positional relationship commonly understood by those skilled in the art, and is only for the convenience of describing the present application and simplifying the description, and is not intended to indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0032] Please refer to Figure 1 , Figure 2 The embodiment provides a manufacturing method of a PCB with a stepped impedance strip, comprising the following steps:

[0033] Preparation: prepare an upper sub-board 1 and an impedance strip lower sub-board 2, and the top surface of the impedance strip region of the impedance strip lower sub-board 2 is provided with an impedance line 3. The impedance line 3 is a key structure for guaranteeing the integrity of signal transmission, and the setting position thereof determines the region that needs to be focused on protection and processing in subsequent processing, so as to ensure that the final PCB can realize accurate impedance control. The upper sub-board 1 and the impedance strip lower sub-board 2 are the main objects of subsequent processing, and are both multilayer boards, that is, have been pressed once, thereby providing a material basis for the structure formation of the entire PCB. The length and width dimensions of the upper sub-board 1 and the impedance strip lower sub-board 2 are the same, so that the upper and lower sub-boards can be accurately aligned in the pressing process, and problems such as misalignment and gap caused by size difference are avoided, thereby ensuring the overall structural stability and performance consistency of the PCB.

[0034] Applying High-Temperature Tape: Apply high-temperature tape to the impedance bonding area, ensuring that the ends of all impedance lines 3 are exposed above the tape (i.e., not covered by tape), while the remaining portions are covered by it. The high-temperature tape acts as an insulator, ensuring that the ends of the impedance lines 3 can be processed normally in subsequent drilling and electroplating processes. It also creates a vertical separation between the waste area and the impedance bonding area, preventing them from sticking together during subsequent lamination. This lays the foundation for the step-like structure. Furthermore, the high-temperature tape can withstand the high temperatures during lamination, hence its use. The thickness of the high-temperature tape is 60-80mm, preferably 70mm. This thickness ensures effective isolation while accommodating the ease of operation in subsequent milling and controlled-depth milling processes, as well as the rationality of the final step-like structure. If the high-temperature tape is too thin, it may not effectively isolate the waste area; if it is too thick, it may increase the process difficulty and cost, affecting the overall performance of the PCB board.

[0035] Cutting the waste edges of the high-temperature tape: A CO2 laser drill is used to cut the waste edges of the high-temperature tape. The CO2 laser drill has advantages such as high processing precision, high speed, and a small heat-affected zone, enabling precise cutting of the waste edges of the high-temperature tape. This ensures the flatness and smoothness of the cut edges, reducing defects such as burrs and flash generated during the cutting process, and preventing these defects from adversely affecting subsequent processes and PCB board performance. Specifically, the CO2 laser drill has a spot diameter of 4-8 mil and a cutting spacing of 1-3 mil. This spot diameter and cutting spacing setting accurately removes the waste edges of the high-temperature tape while avoiding excessive damage to the high-temperature tape surrounding the cutting area, ensuring the integrity and isolation performance of the high-temperature tape.

[0036] The width of the cut high-temperature tape is the same as the width of the impedance bonding area, ensuring that the high-temperature tape can completely cover the impedance bonding area, achieving comprehensive and effective isolation and preventing contact interference between the waste area and the impedance bonding area in the width direction. At the same time, the distance between the cut high-temperature tape and the end of the impedance line 3 is not less than 2mm. Since the through hole 4 penetrates all layers and corresponds to the end of the impedance line 3, and electroplating is required, maintaining a sufficient distance can prevent the electroplating solution from seeping under the high-temperature tape, avoiding the formation of delamination and making subsequent processes impossible.

[0037] PP milling: Milling grooves in the area of the PP layer at the bottom of the upper subplate 1 corresponding to the high-temperature adhesive tape to form an adhesive tape accommodating groove, providing space for the high-temperature adhesive tape. The depth of the adhesive tape accommodating groove is the same as the thickness of the high-temperature adhesive tape to facilitate the overall board surface to remain the same plane after pressing, avoiding uneven board surface due to inappropriate size of the adhesive tape accommodating groove, ensuring the flatness of the PCB board and reducing subsequent depth control milling errors caused by uneven board surface.

[0038] Pressing: Pressing the upper subplate 1 after milling and the impedance strip lower subplate 2 after pasting the adhesive tape to form a whole board, realizing stable connection between layers. During the pressing process, the high-temperature adhesive tape plays an isolation role, ensuring that the waste area and the impedance strip area are not bonded, creating conditions for subsequent removal of the waste area, while ensuring the structural stability and signal transmission performance of the whole board.

[0039] Drilling and plating: Drilling through holes 4 on the whole board and plating the through holes 4 for conduction, each through hole 4 corresponds to the head end of an impedance line 3. Through the plated through holes 4, the inner layer impedance line 3 can be connected to the top and / or bottom layer of the PCB board for impedance testing.

[0040] Depth control milling and tape tearing: Using a mechanical depth control milling machine to remove the corresponding waste area above the high-temperature adhesive tape in the whole board and tear off the high-temperature adhesive tape to obtain a PCB board with a stepped impedance strip. The thickness of the waste area is the same as the thickness of the upper subplate 1, and the length and width of the waste area are 4-8 mil larger than those of the cut high-temperature adhesive tape. By removing the corresponding waste area above the high-temperature adhesive tape through depth control milling, the interference of the waste area on the impedance is effectively reduced, and the accuracy of the impedance value determination is improved. Since the presence of the high-temperature adhesive tape in the final product will affect the actual effect of the stepped impedance strip, tearing off the high-temperature adhesive tape can further optimize the structural performance of the stepped impedance strip, making it better to reduce interference and protect signal transmission.

[0041] Wherein, since the waste area thickness is same as the thickness of the upper sub-plate 1, the milling depth can be accurately controlled by using a mechanical depth control milling machine, so as to ensure that the corresponding waste area above the high-temperature adhesive tape is completely and accurately removed, so that the impedance via area and the area after removing the waste form an obvious stepped structure. The length and width of the waste area are 4-8 mil larger than the length and width of the cut high-temperature adhesive tape, so as to ensure that the waste area corresponding to the high-temperature adhesive tape can be completely removed during the depth control milling operation, so as to avoid that part of the waste is left due to size deviation; meanwhile, the impedance via area or other key structures will not be damaged due to the too large depth control milling range, so as to ensure the integrity and quality stability of the PCB.

[0042] In summary, the manufacturing method of the application selectively removes the waste area above the impedance line 3 by processes such as material preparation, adhesive tape pasting, adhesive tape cutting, PP slot milling, pressing, drilling, electroplating, depth control milling, adhesive tape tearing, etc., to form a stepped impedance via structure, so as to greatly reduce the interference of the waste area on the impedance, improve the accuracy of the impedance value determination, and especially suitable for high-precision impedance control scenes of high-end high-speed PCBs, and provide reliable guarantee for the integrity of high-frequency signal transmission.

[0043] In addition, although the operations of the method of the application are described in a specific order in the drawings, this does not require or imply that the operations must be performed in that specific order, or that all of the illustrated operations must be performed to achieve the desired result. Additionally or alternatively, certain steps can be omitted, combined into a single step, and / or divided into multiple steps.

[0044] It should be understood that those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall fall within the protection scope of the appended claims of the application.

[0045] The above has described the application by way of example in connection with the drawings. Obviously, the implementation of the application is not limited to the above manner, and various improvements or direct applications of the technical concept and technical scheme of the application to other fields without improvement are within the protection scope of the application.

Claims

1. A method for manufacturing a PCB board with stepped impedance, characterized in that, include: Preparation: Prepare the upper sub-board and the lower impedance bonding sub-board. The impedance bonding area of ​​the lower impedance bonding sub-board is provided with impedance lines on the top surface. Applying tape: Apply high-temperature tape to the impedance bonding area, with the ends of all impedance wires protruding from the high-temperature tape and the rest covered by the high-temperature tape; Cutting the waste edges of the tape: The waste edges of the high-temperature tape are cut; PP milling groove: A groove is milled in the PP layer at the bottom of the upper sub-board corresponding to the area of ​​the high-temperature tape to form a tape receiving groove; Pressing: Press the upper sub-board after milling the grooves with the lower sub-board after applying adhesive tape to form a whole board; Drilling and electroplating: Drill through holes in the entire board and electroplat the through holes to make them conductive. Each through hole corresponds to the end of an impedance line. Controlled depth milling and tape removal: A mechanical controlled depth milling machine is used to remove the waste area corresponding to the high-temperature tape on the whole board and to remove the high-temperature tape, thereby obtaining a PCB board with stepped impedance.

2. The method for manufacturing a PCB board with stepped impedance according to claim 1, characterized in that, The distance between the cut high-temperature tape and the end of the impedance wire shall be no less than 2 mm.

3. The method for manufacturing a PCB board with stepped impedance according to claim 1, characterized in that, The width of the cut high-temperature tape is the same as the width of the impedance bonding area.

4. The method for manufacturing a PCB board with stepped impedance according to claim 1, characterized in that, The thickness of the high-temperature tape is 60-80mm.

5. The method for manufacturing a PCB board with stepped impedance according to claim 1, characterized in that, The thickness of the high-temperature tape is the same as the depth of the tape receiving groove.

6. The method for manufacturing a PCB board with stepped impedance according to claim 1, characterized in that, The length and width of the tape receiving groove are both larger than the length and width of the cut high-temperature tape.

7. The method for manufacturing a PCB board with stepped impedance according to claim 6, characterized in that, The length and width of the tape receiving groove are both 3-8 mil larger than the length and width of the cut high-temperature tape.

8. The method for manufacturing a PCB board with stepped impedance according to claim 1, characterized in that, The thickness of the waste area is the same as the thickness of the upper sub-board, and the length and width of the waste area are both greater than the length and width of the cut high-temperature tape.

9. The method for manufacturing a PCB board with stepped impedance according to claim 8, characterized in that, The length and width of the waste area are both 4-8 mil larger than the length and width of the cut high-temperature tape.

10. The method for manufacturing a PCB board with stepped impedance according to claim 1, characterized in that, In the step of cutting the waste edge of the tape, a CO2 laser drill is used to cut the waste edge of the high-temperature tape. The spot diameter of the CO2 laser drill is 4-8 mil, and the cutting spacing is 1-3 mil.

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