Manufacturing method of printed circuit board, printed circuit board and electronic equipment
By using a specific metal layer with a thickness of less than 15um in printed circuit board manufacturing and performing specific process processing, the short circuit problem caused by impurity of etching is solved, and the yield and applicability of the printed circuit board is improved.
Patent Information
- Application Number
- CN202411684685.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-22
- Publication Date
- 2025-02-14
AI Technical Summary
During the manufacturing process of printed circuit boards, when the line distance is small, the etching depth is large, and the etching copper is large, the copper film is not etched clean, resulting in poor short circuits and is not suitable for mass production of thin lines.
By obtaining a specific metal layer of the substrate with a thickness of less than 15um, and performing process processing such as film laying, exposure development, electroplating and film defiling etching, the metal thickness during etching is reduced and the line etching is ensured is clean.
It solves the short circuit problem caused by impurity of etching, improves the yield of printed circuit boards, and is suitable for mass production of thin circuits.
Smart Images
Figure CN119450954A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of electronic technology, and in particular to a method for manufacturing a printed circuit board, a printed circuit board and an electronic device. Background Art
[0002] The manufacturing process of printed circuit boards involves front-end processes such as drilling and copper plating before the circuit manufacturing process, as well as back-end processes such as surface treatment, electrical testing, and inspection after the circuit manufacturing process. Each process step needs to be strictly performed as required to ensure that a printed circuit board with excellent performance is obtained, and the circuit manufacturing process plays a decisive role in the performance of the printed circuit board.
[0003] In the related technologies of circuit manufacturing process, a layer of photosensitive film is usually covered on the surface of copper clad board. This photosensitive film produces curing reaction under the irradiation of specific light. The cured photosensitive film will be tightly adsorbed on the copper surface. The difference between the cured photosensitive film and the uncured photosensitive film can clearly show the direction of the circuit line. Then, based on this difference, the corresponding image transfer process can be used to etch away the copper film of the non-circuit part, and the copper film of the remaining circuit part can form the circuit pattern of the printed circuit board. However, when the line width / line spacing of the line is similar to the thickness of the copper film and the photosensitive film, the line distance is small, the etching depth is large, and the etched copper thickness is large. The etching solution for etching the copper film has poor exchange ability between small line spacings, and it is easy to have incomplete etching of the copper film, resulting in short circuit defects, which is not suitable for mass production of fine lines.
[0004] Therefore, it is now urgent to redesign a method for manufacturing a printed circuit board and overcome the above-mentioned defects. Summary of the invention
[0005] The embodiments of the present application provide a method for manufacturing a printed circuit board, a printed circuit board and an electronic device, which are used to solve the problem that when the circuit distance is small, the etching depth is large, and the etching copper thickness is large, the copper film is not etched cleanly, resulting in a short circuit.
[0006] In a first aspect, an embodiment of the present application provides a method for manufacturing a printed circuit board, comprising:
[0007] Obtaining a substrate, wherein a specific metal layer is disposed on the surface of the substrate, and the specific metal layer has a thickness of less than 15 um;
[0008] Based on the set circuit diagram of the substrate, performing exposure and development processing on the substrate film layer laid on the specific metal layer to expose the specific metal layer corresponding to the set circuit diagram;
[0009] Electroplating the exposed metal on the substrate to thicken the exposed metal to a set metal thickness to obtain an intermediate panel;
[0010] The middle panel is subjected to film stripping and etching treatment to obtain a printed circuit board.
[0011] Optionally, obtaining the substrate includes:
[0012] The raw metal layer on the surface of the raw substrate is reduced in thickness to less than 15 um to obtain the substrate having the specific metal layer less than 15 um.
[0013] Optionally, based on the set circuit diagram of the substrate, performing exposure and development processing on the substrate film layer laid on the specific metal layer to expose the specific metal layer corresponding to the set circuit diagram includes:
[0014] Laying a substrate film layer on the substrate, wherein the thickness of the obtained substrate film layer is greater than the set metal thickness;
[0015] The substrate film layer is exposed and developed to expose the specific metal layer corresponding to the set circuit pattern.
[0016] Optionally, the specific metal layer has a thickness of 2-3 um, the set metal layer has a thickness of 15 um-18 um, and the substrate film layer has a thickness of 19-20 um or 20-21 um.
[0017] Optionally, before laying the substrate film layer on the substrate, the method further includes:
[0018] The substrate is subjected to drilling and micro-etching treatments, wherein the micro-etching treatment is any one of a copper deposition process, a black hole process and a black shadow process.
[0019] Optionally, the specific metal layer has a thickness of 3-4 um, the set metal layer has a thickness of 15 um-18 um, and the substrate film layer has a thickness of 19-20 um or 20-21 um.
[0020] Optionally, the set metal thickness is 18um.
[0021] Optionally, the printed circuit board is a multi-layer circuit board, and the middle panel is subjected to a stripping and etching process to obtain the printed circuit board, including:
[0022] Performing film stripping and etching treatment on the middle panel to obtain an inner core panel;
[0023] Obtain at least one matching core board corresponding to the inner core board, wherein at least one surface of the inner core board and the matching core board has a circuit;
[0024] The inner core board and the at least one matching core board are pressed together to obtain a basic multilayer board, wherein a surface metal layer is provided on the surface of the basic multilayer board, and the thickness of the surface metal layer is less than 15 um;
[0025] Based on the surface circuit diagram of the basic multilayer board, the multilayer board film layer laid on the surface metal layer is exposed and developed to expose the surface metal layer corresponding to the surface circuit diagram;
[0026] Electroplating the exposed metal on the basic multilayer board to increase the exposed metal thickness by the set metal thickness to obtain an intermediate multilayer board;
[0027] The intermediate multilayer board is subjected to film stripping and etching treatment to obtain the printed circuit board.
[0028] In a second aspect, an embodiment of the present application provides a printed circuit board, and the printed circuit board is obtained by using the printed circuit board manufacturing method described in any one of the first aspects above.
[0029] In a third aspect, an embodiment of the present application provides an electronic device, comprising the printed circuit board described in the second aspect.
[0030] The beneficial effects of this application are as follows:
[0031] A method for manufacturing a printed circuit board provided in an embodiment of the present application obtains a substrate with a specific metal layer having a thickness of less than 15 um on the surface, and performs processes such as film laying, exposure, development, electroplating, and film stripping etching on the substrate with the specific metal layer having a thickness of less than 15 um to reduce the metal thickness on the substrate etched during the etching process, thereby solving the problem in the related art that the metal thickness of the substrate is relatively large, resulting in incomplete etching during the etching process, easy short circuits between circuits, and low yield of the printed circuit board.
[0032] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.
[0034] Figure 1 A schematic diagram of a process for manufacturing a printed circuit board provided in an embodiment of the present application;
[0035] Figure 2 A cross-sectional schematic diagram of a double-sided substrate provided in an embodiment of the present application;
[0036] Figure 3 A schematic diagram of the structure of a printed circuit board manufacturing process and a substrate in each process step provided in an embodiment of the present application;
[0037] Figure 4 A schematic diagram of a method for manufacturing a printed circuit board provided in an embodiment of the present application;
[0038] Figure 5 A schematic flow chart of a method for manufacturing a multi-layer circuit board (PCB) - a printed circuit board - is provided in an embodiment of the present application. DETAILED DESCRIPTION
[0039] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other arbitrarily.
[0040] As the functions of electronic products such as smart phones, tablet computers, and smart watches gradually increase, and users have stronger requirements for electronic products, the wiring of printed circuit boards in electronic products has become more complex, the line spacing / line width has become narrower, and flexible printed circuit boards have been developed. This allows more functions to be set in electronic products while ensuring that the electronic products are light and compact.
[0041] In the related art, the flexible printed circuit board, also known as the flexible circuit board (FPCB), has a general manufacturing process including pre-circuit process, circuit manufacturing process and post-circuit process. The pre-circuit process generally includes: double-sided board drilling, black hole, copper plating, so that the double-sided board circuit is conductive, and tool holes for alignment installation can also be made; the circuit manufacturing process includes: double-sided board pre-processing cleaning, dry film pasting, exposure, development, etching, film stripping, circuit optical inspection (AOI), etc., which is used to produce the circuit graphics of the circuit board according to the product design requirements; the post-circuit process includes: double-sided board cleaning, cover film pasting, lamination, curing, surface treatment, lamination reinforcement, characters, curing, appearance process, electrical testing process, inspection process, etc.
[0042] In the circuit manufacturing process of the flexible printed circuit board, the traditional direct etching method is usually used. This method is suitable for the circuit manufacturing process with a process capability of line width\line spacing ≥50um\50um. The factors affecting the circuit process capability include the circuit copper thickness, dry film thickness, exposure machine resolution, etching machine etching capability, etc. Among them, in terms of circuit copper thickness, the general product copper thickness is required to be 15-20um, and the thinnest photosensitive film thickness is 15-20um. When etching the circuit, the copper thickness plus the dry film thickness must reach 30um-40um. If the printed circuit board with a line width / line spacing less than 50um / 50um is made, the circuit distance is small, the etching depth is large (about 30um), and the etching copper thickness is large (required to be 15-20um) during the etching process. The etching solution has poor exchange ability between small line spacings, resulting in unclean circuit etching copper, resulting in short circuit defects, and is not suitable for mass production of printed circuit boards with fine lines.
[0043] In view of this, the present application provides a method for manufacturing a printed circuit board, which reduces the thickness of a specific metal layer on the surface of a substrate to less than 15um, so that the specific metal layer outside the circuit in the set circuit diagram can be etched cleanly during the subsequent etching process of the circuit manufacturing process based on the substrate with a thin specific metal layer, and then a line width and line spacing capability of 15um\15um-50um\50um can be produced. The problem of circuit short circuit caused by incomplete metal etching, low yield of printed circuit boards, and inconvenience for mass production in the related art is solved.
[0044] The following briefly introduces the application scenarios to which the technical solutions of the embodiments of the present application can be applied. It should be noted that the application scenarios introduced below are only used to illustrate the embodiments of the present application and are not limited. In the specific implementation process, the technical solutions provided by the embodiments of the present application can be flexibly applied according to actual needs.
[0045] The solution provided in the embodiment of the present application can be applied to most application scenarios of printed circuit board manufacturing. For example, the printed circuit board manufacturing method provided in the embodiment of the present application can be applied to rigid printed circuit boards, flexible printed circuit boards, single-layer printed circuit boards, multi-layer printed circuit boards, etc., which are not listed one by one here.
[0046] The following describes the method for manufacturing a printed circuit board provided by an exemplary embodiment of the present application in combination with the application scenarios described above and with reference to the accompanying drawings. It should be noted that the above application scenarios are only shown to facilitate understanding of the spirit and principles of the present application, and the implementation of the present application is not limited in this regard.
[0047] See also Figure 1 FIG. 1 is a flow chart of a method for manufacturing a printed circuit board provided in an embodiment of the present application, comprising:
[0048] Step 101: Obtain a substrate, wherein a specific metal layer is disposed on the surface of the substrate, and the thickness of the specific metal layer is less than 15 um.
[0049] Step 102 : Based on the set circuit diagram of the substrate, the substrate film layer laid on the specific metal layer is exposed and developed to expose the specific metal layer corresponding to the set circuit diagram.
[0050] Step 103 , electroplating the metal exposed on the substrate to thicken the exposed metal to a set metal thickness, thereby obtaining an intermediate panel.
[0051] Step 104: Perform film stripping and etching processing on the middle panel to obtain a printed circuit board.
[0052] In one embodiment, the substrate may be a double-sided substrate or a single-sided substrate, such as Figure 2 , which is a cross-sectional schematic diagram of a double-sided substrate provided in an embodiment of the present application, specific metal layers are respectively arranged on both sides of the basic dielectric layer.
[0053] In one embodiment, the basic dielectric layer can be PI (polyimide), the specific metal layer can be a copper layer, and the method of obtaining the raw material substrate can be: an adhesive is set between PI and the copper film as a spacer to increase the bonding strength between PI and the copper film, and the contact surface between the copper film and the PI can be roughened to enhance the adhesion of the copper film, then the copper film is coated on the PI (polyimide), and the PI and the copper film are laminated, and the obtained copper-clad board combined with the PI and the copper film is placed in a corresponding laminating device (such as a laminate chamber), and the laminate chamber is evacuated to make the PI and the copper film in a vacuum state fit tightly, and then the laminate is placed in a hot pressing device, and the activity of the adhesive is stimulated by high temperature and high pressure. The raw material substrate obtained in this way can be used to make a flexible circuit board, and the flexible circuit board can withstand millions of dynamic bendings. It should be noted that the copper-clad board here can be obtained by combining PI with a copper film, or by combining a copper film with other composite materials. A composite material with suitable dielectric parameters can be selected according to the centerline spacing parameters of the printed circuit board.
[0054] Therefore, the copper-clad film can be a copper-clad film less than 15um. If the copper-clad film is too thin and inconvenient for the lamination process, electroplating, infiltration plating and other processes can also be used, or a copper-clad film greater than 15um can be used to make a raw material substrate, and after the production is completed, the copper-clad film on the raw material substrate is etched to less than 15um to obtain a substrate. Similarly, the specific metal layer on the substrate can also be a specific metal layer less than 15um produced on a basic dielectric layer using a specific process, or it can also be obtained by etching a raw material substrate having a raw material metal layer greater than 15um. There is no specific restriction on the method of obtaining a substrate having a specific metal layer less than 15um. The substrate is obtained by preliminary processing of the raw material substrate. The difference between the raw material substrate and the substrate includes the different thickness of the metal layer on the surface, such as the thickness of the specific metal layer on the surface of the substrate is less than 15um, and the thickness of the raw metal layer on the surface of the raw material substrate is greater than 15um.
[0055] In one embodiment, the specific metal layer may be a copper metal layer, a silver metal layer, etc. There is no specific limitation on the selection of the specific metal and it can be set as needed.
[0056] In one embodiment, after obtaining the substrate, the substrate can be designed, cut and trimmed according to the desired shape of the printed circuit board, so that the appearance of the final printed circuit board meets the design requirements and has appropriate mechanical dimensions and smoothness.
[0057] In one embodiment, the set circuit diagram may be a file containing circuits that need to be made on a specific metal layer on the substrate.
[0058] In one embodiment, the present application provides a manufacturing process of a printed circuit board and a schematic diagram of the structure of a substrate in each process step, such as Figure 3 As shown, the substrate film layer laid on the specific metal layer is exposed and developed to expose the specific metal layer corresponding to the set circuit diagram, which can be:
[0059] Step a, film laying: Use a film laminating machine to press a layer of substrate film (photosensitive film sensitive to ultraviolet rays) on the surface of the substrate.
[0060] Step b, exposure: a photomask is set above the photosensitive film. The circuit part of the photomask designed based on the set circuit diagram is black, and the non-circuit part is transparent. Ultraviolet light is used for irradiation. The light only passes through the transparent part of the photomask. The transparent part of the photomask will undergo polymerization and solidify, and the photosensitive film of the solidified part will not be etched.
[0061] Step c, development: Then use a developing solution to dissolve the photosensitive film portion corresponding to the opaque portion of the photomask, exposing the specific metal layer of the circuit portion.
[0062] Step d, electroplating: then electroplating is performed on the substrate with the exposed portion of the specific metal layer, and a specific metal with a set metal thickness is electroplated on the exposed specific metal layer to thicken the exposed metal to the set metal thickness, thereby obtaining an intermediate panel.
[0063] Step e, film stripping: For the obtained middle panel, use high-performance film stripping solution to strip and clean the circuit board. Note that the film needs to be stripped cleanly during this process.
[0064] Step f, etching: using an etching process (if the specific metal layer is a copper film, a copper reduction process can also be used), the specific metal layer on the middle panel after the film is removed is uniformly etched to a certain thickness to obtain an middle panel with a set circuit pattern in a set circuit diagram, and then, double-panel cleaning, covering film pasting, lamination, curing, surface treatment, lamination reinforcement, character, curing, appearance process, electrical testing process, inspection process and other post-processing processes are carried out. In the process of manufacturing rigid circuit boards (rigid printed circuit boards) or flexible circuit boards (flexible printed circuit boards), the back-end process can be correspondingly the same as the conventional rigid circuit board or flexible circuit board process, and the design needs to be produced. The process of the back-end process is not specifically limited here and can be set as needed.
[0065] Among them, the etching thickness is the thickness of the specific metal layer, so as to etch away the specific metal of the non-line part on the substrate. In order to ensure clean etching, the etching thickness can be set to be greater than the thickness of the specific metal layer. Correspondingly, in order to ensure that the original specific metal layer thickness of the substrate + the specific metal layer thickness of the electroplating meets the line thickness (set metal thickness) requirement, during electroplating, the set metal thickness of the electroplating can make the thickness of the original specific metal layer thickness of the substrate + the set metal thickness and exceed the line thickness requirement. The excess thickness can be used to offset the etching when etching the specific metal of the non-line part of the substrate.
[0066] In the manufacturing process of the above-mentioned printed circuit board, a substrate with a specific metal layer with a thickness of less than 15um is obtained, and based on the substrate with a specific metal layer with a thickness of less than 15um, process treatments such as film laying, exposure, development, electroplating and film stripping etching are carried out to reduce the metal thickness on the substrate etched during the etching process, thereby solving the problem in the related art that the metal thickness of the substrate is large, resulting in incomplete etching during the etching process, easy short circuit between circuits, and low yield of the printed circuit board.
[0067] Based on the above Figure 1 In the method flow, the embodiment of the present application provides a method for obtaining a substrate. In step 101, a substrate is obtained, including:
[0068] The raw metal layer on the surface of the raw material substrate is reduced in thickness to less than 15 um, thereby obtaining a substrate having a specific metal layer less than 15 um.
[0069] In one embodiment, an etching solution is used to reduce the thickness of the raw metal layer on the surface of the raw substrate to less than 15 um. Here, the thinner the metal layer on the surface of the raw substrate is, the more conducive it is to cleanly etch the metal of the non-circuit part.
[0070] In one embodiment, if the raw metal layer is copper, the raw metal layer on the surface of the raw substrate can be reduced in thickness to less than 15 um based on a copper reduction process to obtain a substrate.
[0071] Based on the above Figure 1 The method flow in the embodiment of the present application provides a method for manufacturing a printed circuit board. In step 102, based on the set circuit diagram of the substrate, the substrate film layer laid on the specific metal layer is exposed and developed to expose the specific metal layer corresponding to the set circuit diagram, including:
[0072] Step (1), laying a substrate film layer on the substrate, and the thickness of the obtained substrate film layer is greater than the set metal thickness.
[0073] Step (2), exposing and developing the substrate film layer to expose the specific metal layer corresponding to the set circuit pattern.
[0074] In one embodiment, the thickness of the substrate film layer laid on the substrate is greater than the set metal thickness of the electroplating, such as Figure 3 As shown in step d, in this way, it is ensured that when a specific metal with a set metal thickness is subsequently electroplated, the substrate film layer will not be covered, resulting in the inability to completely remove the film later. If the film is not removed cleanly, the subsequent etching will be affected, resulting in incomplete etching and short circuit of the circuit. The thickness difference between the substrate film layer thickness and the set metal thickness of the electroplating can be set according to the process requirements, and there is no specific limitation here.
[0075] Based on the above Figures 1 to 3 As shown in the process flow chart and structure diagram, the embodiment of the present application provides a method for manufacturing a printed circuit board. During the manufacturing process, the thickness of the specific metal layer on the surface of the substrate is 2-3um, the set metal thickness obtained by electroplating is 15um-18um, and the thickness of the film layer of the film-laid substrate is 19-20um or 20-21um.
[0076] In one embodiment, if there is a micro-etching process before / before the circuit manufacturing process, it is necessary to control the thickness of the specific metal layer on the substrate according to the micro-etching amount of the relevant process to ensure that after the micro-etching process before / before the circuit manufacturing process, the thickness of the specific metal layer of the substrate before electroplating is 2-3um. For example, if there is a micro-etching process before / before the circuit manufacturing process, and the micro-etched metal thickness is about 1um, the specific metal thickness on the surface of the raw material substrate can be reduced to 2-5um through the copper reduction process, so that after the micro-etching process before / before the circuit manufacturing process, the specific metal layer thickness obtained is 2-3um. The thinner the metal layer on the surface of the substrate, the more conducive to circuit etching.
[0077] Based on the above Figures 1 to 3 As shown in the process flow chart and structure diagram, the embodiment of the present application provides a method for manufacturing a printed circuit board, before laying a substrate film layer on the substrate in step 102, the method further includes:
[0078] The substrate is subjected to drilling and micro-etching processes, wherein the micro-etching process is any one of a copper deposition process, a black hole process and a black shadow process.
[0079] In one embodiment, the drilling process can be used to connect the circuits on both sides of the substrate. If the printed circuit board is a multi-layer circuit board, the drilling can include through holes, buried holes, and mounting holes. Among them, the through holes penetrate the multi-layer circuit board. The through holes can be used to connect electronic components and are mainly used to connect multi-layer circuit boards. The buried holes connect the unexposed internal circuits, so the through holes and buried holes need to be micro-etched to plate the specific metal of the specific metal layer (if the specific metal of the specific metal layer is copper, copper can be plated, such as chemical copper deposition), black holes or black shadows. After completion, the through holes and buried holes are connected. The mounting holes are used to fix the circuit board.
[0080] Among them, the black hole process is to carbonize the inside of the hole so that the dielectric layer on the hole wall can be electroplated and conductive. This process requires strict control of the amount of micro-etching in the process and strict control of related rework steps to ensure that the micro-etching metal thickness of this process is designed according to the process.
[0081] Based on the above-mentioned method for manufacturing a printed circuit board including micro-etching, the embodiment of the present application provides a method for manufacturing a printed circuit board, wherein the thickness of a specific metal layer in the manufacturing process is 3-4um, the metal thickness is set to 15um-18um, and the thickness of the substrate film layer is 19-20um or 20-21um. In this way, the 3-4um specific metal layer can offset the micro-etching amount of the micro-etching part before the circuit manufacturing process, obtain a 2-3um specific metal layer, and enter the circuit manufacturing process.
[0082] In one embodiment, the metal thickness is set to 18 um.
[0083] Based on the above-mentioned manufacturing methods and related embodiments of printed circuit boards, the present application provides a manufacturing method of a printed circuit board, taking the processing of a double-sided specific metal layer of a substrate, and the metal of the specific metal layer is copper as an example, such as Figure 4 As shown, including:
[0084] Step 401, thinning process: the original copper film on the surfaces of both sides of the raw material substrate is reduced in thickness to less than 15 um, so as to obtain a substrate with a copper film thickness of less than 15 um on both sides.
[0085] Here, if the raw metal layer is copper, a copper reduction process can be used to reduce the raw substrate copper thickness to 2-5um. If there is no micro-etching copper process before the circuit etching process, the copper thickness can be controlled to 2-3um. The thinner the substrate copper, the more conducive to circuit etching. That is to say, if there is a micro-etching copper process, the thickness of the substrate copper needs to be controlled according to the micro-etching amount of the relevant process to ensure that after these processes, the substrate copper thickness obtained based on the raw substrate before electroplating is 2-3um.
[0086] If a black hole process is required, the copper needs to be micro-etched 1.0um according to the black hole process, so the copper thickness of the copper reduction control is controlled to 3-4um, that is, the thickness of the specific metal layer on the surface of the substrate is 3-4um, and the copper is micro-etched 1.0um before the circuit production process, and the thickness of the remaining specific metal layer is 2-3um, and then enters the subsequent circuit production process. Here, you can also directly ask the material factory to provide the substrate copper raw material of the required thickness, which can reduce the cost of the copper reduction process and improve the uniformity of the substrate copper.
[0087] Step 402, drilling process: using the through holes obtained by drilling to connect the circuits on both sides of the substrate.
[0088] Step 403, black hole process: carbonization treatment is performed inside the through hole to enable the dielectric layer on the hole wall to be electroplated and conductive. This process requires strict control of the micro-etching amount of the process and strict control of related rework steps to ensure that the micro-etching copper thickness of this process is designed according to the process.
[0089] Step 404, film laying process (dry film pasting process): a dry film (substrate film layer) with a thickness of 20um is pasted on the substrate (if a flexible printed circuit board is manufactured, the substrate is a flexible board). The thickness of the dry film needs to refer to the copper thickness of the circuit. If the copper thickness of the circuit is required to be 15-18um, a dry film with a thickness of 20um can be used. If the copper thickness of the circuit is required to be greater than 18um, it is necessary to select a dry film with a thickness greater than the designed electroplated copper thickness to ensure that the electroplated copper will not clamp the dry film. When pasting the dry film, attention should be paid to the bonding strength between the dry film and the copper surface to avoid poor shedding of the dry film after development. This can be controlled by cleaning the copper surface of the substrate, controlling the time from cleaning the copper surface to pasting the dry film, adjusting the parameters for pasting the dry film, and other methods.
[0090] In one embodiment, relevant parameters that can be implemented in a dry film pasting process include: if the design is to electroplate 15-18um copper, chemical cleaning is performed before dry film pasting, dry film pasting is completed within 1 hour, the dry film thickness is 20um, the film pasting speed is 0.8-1.0 meters per second, the temperature is 100-110°C, and the film is left to stand for more than 1 hour after pasting.
[0091] Step 405, exposure process: using an exposure machine (laser direct imaging, LDI) to expose the non-circuit portion, so that the dry film of the non-circuit portion reacts and adheres closely to the surface of the specific metal layer.
[0092] If the minimum design line capacity is 20um / 20um, the resolution of the exposure machine is one of the key factors that determine the limit capacity of the line, so a high-performance exposure machine needs to be selected.
[0093] Step 406, development process: using a developing solution to dissolve and clean the dry film of the circuit part to develop a pattern on the substrate. After development, the designed circuit pattern will not retain the dry film, and only the dry film of the non-circuit etching area will be retained.
[0094] After that, the substrates need to be separated and placed with dust-free partition films or white paper, and stored and transferred in a dust-free workshop or board box to reduce exposure during the next process to avoid dust on the board causing poor circuit plating.
[0095] Step 407, electroplating process: calculate the electroplating parameters according to the electroplating area of the designed film pattern, and perform pattern electroplating on the product; after the electroplating is completed, the circuit copper is directly electroplated on the copper surface of the substrate circuit, and the electroplated copper thickness can be 18um.
[0096] Step 408, dry film stripping process: Use high-performance film stripping solution to perform film stripping and cleaning to clean the dry film on the non-circuit part of the electroplated substrate.
[0097] Step 409, etching process: Use copper reduction line or etching line to control the parameters of uniformly etching the circuit board to 3-4um copper thickness, etch the low copper (specific metal layer of the non-circuit part of the substrate) cleanly, and make a circuit pattern.
[0098] Step 410, post-processing steps: double-sided board cleaning, covering film pasting, lamination, curing, surface treatment, lamination reinforcement, character, curing, shape process, electrical testing process, inspection process, etc.
[0099] Based on the above Figure 1-4The method flow, structure and related embodiments involved in the present application provide a method for manufacturing a multi-layer circuit board-printed circuit board, wherein the printed circuit board is a multi-layer circuit board. In step 104, the middle panel is subjected to film stripping and etching to obtain the printed circuit board, including:
[0100] Step 501: Perform film stripping and etching processing on the middle panel to obtain the inner core panel.
[0101] In one embodiment, both sides of the inner core board may have circuits, or one side may have circuits and the other side may be a complete specific metal layer.
[0102] Step 502: Obtain at least one matching core board corresponding to the inner core board, wherein at least one surface of the inner core board and the matching core board has circuits.
[0103] In one embodiment, the matching core board is obtained by the same process as the inner core board, that is, a substrate with a specific metal layer less than 15um thick is obtained on the surface, and based on the matching circuit diagram of the matching core board, the substrate film layer laid on the specific metal layer is exposed and developed to expose the specific metal layer corresponding to the matching circuit diagram, and the exposed metal on the substrate is electroplated to thicken the exposed metal to a set metal thickness to obtain an intermediate panel, and the intermediate panel is stripped and etched to obtain the matching core board. The matching circuit diagram can match the set circuit diagram corresponding to the inner core board to achieve certain electrical functions.
[0104] In one embodiment, the multi-layer circuit board can be obtained by stacking two core boards, and the inner core board and the matching core board both have circuits on one side and a complete specific metal layer on the other side.
[0105] In one embodiment, the multilayer circuit board can be larger than the two layers of core boards stacked together, and the inner core board can have circuits on both sides. Among at least two matching core boards, there are two matching core boards with circuits on one side, and the other side of these two matching core boards is a complete specific metal layer. In the stacked structure, the surfaces with complete specific metal layers on both sides are on the outside of the multilayer circuit board for the subsequent circuit manufacturing process. Among them, if there is a matching core board in addition to the two matching core boards with circuits on one side, the matching core board can have circuits on both sides.
[0106] In one embodiment, the multi-layer circuit board can be larger than the two-layer core board stacked, the inner core board can have a circuit on one side and a complete specific metal layer on the other side, and at least one of the two matching core boards has a circuit on one side, and the other side of this matching core board has a complete specific metal layer. In the stacked structure, the surfaces with complete specific metal layers on both sides are on the outside of the multi-layer circuit board for the subsequent circuit manufacturing process. Among them, if there is a matching core board in addition to the matching core board with circuits on one side, the matching core board can have circuits on both sides.
[0107] Step 503: Press-bond the inner core board and at least one matching core board to obtain a basic multilayer board, wherein the surface of the basic multilayer board has a surface metal layer, and the thickness of the surface metal layer is less than 15 um.
[0108] In one embodiment, the inner core board and at least one matching core board may be pressed together using a browning riveting process. During the pressing process, an insulating sheet is disposed between the core boards, and the insulating sheet is tightly combined with the adjacent core boards during the pressing process.
[0109] Among them, browning: let the core board react with the browning liquid to form a dense organic browning film on the copper surface of the core board to enhance the bonding strength between the core board and the PP sheet (prepreg). This process is after the inner layer is etched and before lamination. The purpose is to enhance the bonding strength between the core board and the prepreg. Riveting: Use rivets to connect multiple overlapping core boards.
[0110] Step 504: Based on the surface circuit diagram of the basic multilayer board, the multilayer board film layer laid on the surface metal layer is exposed and developed to expose the specific metal layer corresponding to the surface circuit diagram.
[0111] In one embodiment, the basic multilayer board has at least two layers of circuits inside, and the surface of the basic multilayer board can be subjected to a circuit manufacturing process according to the surface circuit diagram to obtain the circuits on the surface of the basic multilayer board.
[0112] Step 505, electroplating the exposed metal on the basic multilayer board to thicken the exposed metal by a set metal thickness to obtain an intermediate multilayer board;
[0113] Step 506: Perform film stripping and etching processing on the middle multilayer board to obtain a printed circuit board.
[0114] In one embodiment, after the middle multilayer board is stripped and etched, double-sided board cleaning, covering film pasting, lamination, curing, surface treatment, pressing and reinforcement, characterization, curing, appearance process, electrical testing process, inspection process, etc. can be performed to finally obtain a printed circuit board.
[0115] Based on the above Figure 1 , Figure 2-5A method for manufacturing a printed circuit board in the present application embodiment provides a printed circuit board, which can be a printed circuit board using Figure 1 , Figure 2-5 The method for manufacturing any printed circuit board is obtained.
[0116] Based on the above Figure 1 , Figure 2-5 A method for manufacturing a printed circuit board in the present application provides an electronic device, wherein the electronic device is provided with a Figure 1 , Figure 2-5 A printed circuit board obtained by any of the manufacturing methods.
Claims
1. A method for manufacturing a printed circuit board, characterized in that: include: Obtaining a substrate, wherein a specific metal layer is disposed on the surface of the substrate, and the specific metal layer has a thickness of less than 15 um; Based on the set circuit diagram of the substrate, performing exposure and development processing on the substrate film layer laid on the specific metal layer to expose the specific metal layer corresponding to the set circuit diagram; Electroplating the exposed metal on the substrate to thicken the exposed metal to a set metal thickness to obtain an intermediate panel; The middle panel is subjected to film stripping and etching treatment to obtain a printed circuit board.
2. The manufacturing method according to claim 1, characterized in that The step of obtaining a substrate comprises: The raw metal layer on the surface of the raw substrate is reduced in thickness to less than 15 um to obtain the substrate having the specific metal layer less than 15 um.
3. The manufacturing method according to claim 1, characterized in that: The method of performing exposure and development processing on the substrate film layer laid on the specific metal layer based on the set circuit diagram of the substrate to expose the specific metal layer corresponding to the set circuit diagram includes: Laying a substrate film layer on the substrate, wherein the thickness of the obtained substrate film layer is greater than the set metal thickness; The substrate film layer is exposed and developed to expose the specific metal layer corresponding to the set circuit pattern.
4. The manufacturing method according to claim 3, characterized in that: The specific metal layer thickness is 2-3um, the set metal thickness is 15um-18um, and the substrate film layer thickness is 19-20um or 20-21um.
5. The manufacturing method according to claim 3, characterized in that: Before laying the substrate film layer on the substrate, the method further includes: The substrate is subjected to drilling and micro-etching treatments, wherein the micro-etching treatment is any one of a copper deposition process, a black hole process and a black shadow process.
6. The manufacturing method according to claim 5, characterized in that: The specific metal layer thickness is 3-4um, the set metal thickness is 15um-18um, and the substrate film layer thickness is 19-20um or 20-21um.
7. The manufacturing method according to any one of claims 1 to 6, characterized in that: The set metal thickness is 18um.
8. The manufacturing method according to claim 1, characterized in that: The printed circuit board is a multi-layer circuit board, and the middle panel is subjected to film stripping and etching treatment to obtain the printed circuit board, including: Performing film stripping and etching treatment on the middle panel to obtain an inner core panel; Obtain at least one matching core board corresponding to the inner core board, wherein at least one surface of the inner core board and the matching core board has a circuit; The inner core board and the at least one matching core board are pressed together to obtain a basic multilayer board, wherein the surface of the basic multilayer board has a surface metal layer, and the thickness of the surface metal layer is less than 15 um; Based on the surface circuit diagram of the basic multilayer board, the multilayer board film layer laid on the surface metal layer is exposed and developed to expose the surface metal layer corresponding to the surface circuit diagram; Electroplating the exposed metal on the basic multilayer board to increase the exposed metal thickness by the set metal thickness to obtain an intermediate multilayer board; The intermediate multilayer board is subjected to film stripping and etching treatment to obtain the printed circuit board.
9. A printed circuit board, characterized in that: The method for manufacturing a printed circuit board is used to obtain the printed circuit board.
10. An electronic device, characterized in that: Comprising the printed circuit board as claimed in claim 9.