Manufacturing method of printed circuit board and printed circuit board

Abstract

The embodiment of the invention provides a manufacturing method of a printed circuit board and the printed circuit board, and relates to the technical field of electronics, and the method comprises the steps: obtaining a raw material substrate, and arranging a line metal layer on the surface of the raw material substrate; pasting a protective film on the surface of the circuit metal layer of the raw material substrate to obtain a film-pasted substrate, drilling the film-pasted substrate, and removing the protective film pasted on the surface of the film-pasted substrate to obtain a front-section substrate; and performing exposure development processing and electroplating processing on the front-section substrate to obtain the printed circuit board. The problems that a metal layer on the surface of a substrate is thin, orifice deformation is caused in the drilling process, drilling wire drawing is abnormal, the drilling cost is high, and the efficiency is low are solved.

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 and a printed circuit board. Background Art

[0002] Printed circuit board (PCB), also known as printed circuit board, is the support of electronic components and can provide line connection between electronic components. Compared with relying on wires to connect electronic components to form a complete circuit, using printed circuit boards to provide line connection between electronic components can reduce the size of electronic equipment and reduce the manufacturing cost of electronic equipment. The relevant manufacturing process of printed circuit boards involves front-end processes such as drilling and copper plating before the circuit manufacturing process, exposure and development of the circuit manufacturing process, and back-end processes such as surface treatment, electrical testing process, and inspection process after the circuit manufacturing process. Each process step needs to be strictly executed in accordance with the requirements 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, exposure, development and etching are usually used to etch away the non-circuit part of the copper film on the surface of the substrate, and the remaining circuit metal is used as the circuit to connect electronic components. During the etching process, if the copper film of the substrate is relatively thick, the phenomenon of incomplete etching and circuit short circuit may occur, which will lead to low yield of printed circuit boards. If the copper film of the substrate is thinned, although the problems of incomplete etching and circuit short circuit can be solved, the thin copper film will be subjected to force when the drill bit is pulled up in the drilling process before the circuit manufacturing process, and the hole deformation and drilling wire drawing will occur abnormally, affecting the yield of the printed circuit board. In addition, the thin copper film requires a precision drill bit to work, which is costly. In addition, the precision drill bit can only drill holes in 2-3 stacked substrates each time, and the drilling efficiency is low.

[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 embodiment of the present application provides a method for manufacturing a printed circuit board and a printed circuit board, which are used to solve the problems of thin metal layer on the surface of the substrate, hole deformation in the drilling process, abnormal drilling wire drawing, high drilling cost and low efficiency.

[0006] In a first aspect, an embodiment of the present application provides a method for manufacturing a printed circuit board, comprising:

[0007] Obtaining a raw material substrate, wherein a circuit metal layer is provided on the surface of the raw material substrate;

[0008] A protective film is attached to the surface of the circuit metal layer of the raw substrate to obtain a film-attached substrate, and after drilling the film-attached substrate, the protective film attached to the surface of the film-attached substrate is removed to obtain a front-end substrate;

[0009] The front-end substrate is subjected to exposure, development and electroplating treatments to obtain a printed circuit board.

[0010] Optionally, after drilling the film-attached substrate, removing the protective film attached to the surface of the film-attached substrate to obtain the front-end substrate includes:

[0011] After the film-attached substrate is subjected to the drilling and micro-etching treatments, the protective film attached to the surface of the film-attached substrate is removed to obtain the front-end substrate, and the micro-etching treatment is any one of copper plating, black hole and black shadow processes.

[0012] Optionally, obtaining a raw material substrate comprises:

[0013] The raw metal layer on the surface of the raw material substrate is reduced in thickness to less than 15 um, so as to obtain the raw material substrate having the circuit metal layer less than 15 um.

[0014] Optionally, the circuit metal layer has a thickness of 2-3 um or 3-4 um.

[0015] Optionally, the protective film is a protective copper film, one side of the protective copper film is provided with a tearable adhesive, and the protective film is attached to the surface of the circuit metal layer of the raw substrate to obtain a film-attached substrate, comprising:

[0016] The protective copper film having a tearable adhesive surface is pressed onto the surface of the circuit metal layer of the raw material substrate, and roller pressing is performed to obtain the film-attached substrate.

[0017] Optionally, the protective copper film is 15-18um or 18-21um; in the roller pressing process, the roller pressure is 4.5-5KG / cm 2 or 5.5-6KG / cm 2 , roller speed 0.8-1.0m / min or 1.0-1.2m / min, roller temperature: 50-60℃ or 60-70℃.

[0018] Optionally, removing the protective film attached to the surface of the film-attached substrate to obtain the front-end substrate includes:

[0019] The protective film is torn off from the surface of the film-attached substrate to obtain the front-stage substrate.

[0020] Optionally, the step of performing exposure, development and electroplating on the front-end substrate to obtain a printed circuit board includes:

[0021] Based on the set circuit of the front-end substrate, the substrate film layer laid on the circuit metal layer is exposed and developed to expose the circuit metal layer corresponding to the set circuit;

[0022] Electroplating the metal exposed on the front-stage substrate to increase the thickness of the exposed metal to a preset metal thickness, thereby obtaining an intermediate circuit board, wherein the thickness of the substrate film layer is greater than the preset metal thickness;

[0023] The intermediate circuit board is subjected to film stripping and etching treatment to obtain a printed circuit board.

[0024] Optionally, the preset metal thickness is 15um-18um or 18-19um, and the substrate film layer thickness is 19-20um or 20-21um.

[0025] In a second aspect, an embodiment of the present application provides a printed circuit board, which is obtained by using any of the methods for manufacturing a printed circuit board described in the first aspect above.

[0026] The beneficial effects of this application are as follows:

[0027] The present application provides a method for manufacturing a printed circuit board, including obtaining a raw material substrate with a circuit metal layer on the surface, attaching a protective film to the surface of the circuit metal layer of the raw material substrate, performing a drilling process after attaching the protective film, and removing the attached protective film after the drilling process. In this way, during the drilling process, since the protective film is attached to the circuit metal layer, when the drill bit is pulled up, the protective film replaces the thin circuit metal layer to bear force at the hole mouth, preventing the thin circuit metal layer at the hole mouth from deformation and wire drawing, so as to improve the yield of the printed circuit board, and since the protective film protects the thin circuit metal layer, an ordinary drill bit can be used for drilling, and the drilling cost is low. Therefore, the ordinary drill bit can work each time to drill more than three stacked substrates, and the drilling efficiency is high.

[0028] 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

[0029] 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.

[0030] Figure 1 A schematic diagram of a method for manufacturing a printed circuit board provided in an embodiment of the present application;

[0031] Figure 2 A schematic cross-sectional view of a double-sided substrate provided in an embodiment of the present application;

[0032] Figure 3 A cross-sectional schematic diagram of a double-sided substrate-film substrate provided in an embodiment of the present application;

[0033] Figure 4 A schematic diagram of a method for manufacturing a printed circuit board provided in an embodiment of the present application;

[0034] Figure 5 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;

[0035] Figure 6 A schematic flow chart of a method for manufacturing a printed circuit board provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] 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.

[0037] In the circuit manufacturing process of printed circuit boards, a layer of photosensitive film is usually covered on the copper film of the substrate. This photosensitive film produces a curing reaction under the irradiation of specific light. The cured photosensitive film will be tightly adsorbed on the copper film, and the circuit can be drawn on the photomask, that is, the circuit part is a light-shielding template and the non-circuit part is a non-light-shielding template. The photomask is aligned and laid on the photosensitive film, so that the photosensitive film after light exposure is divided into a cured photosensitive film and an uncured photosensitive film. Then, the difference between the cured photosensitive film and the uncured photosensitive film can clearly show the direction of the circuit. Based on this difference, the corresponding image transfer process can be used. , the copper film of the substrate in the non-circuit part is etched away, 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 circuit 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 etching copper thickness is large. The etching solution for etching copper has poor exchange capacity between small line spacings, which is prone to incomplete copper etching, resulting in poor short circuits. It is not suitable for mass production of fine circuits. To solve this problem, the copper film of the substrate can be thinned before the circuit manufacturing process, and a certain thickness of copper can be electroplated on the circuit part after exposure and development to obtain the copper thickness required for the circuit. When etching, only a very thin copper film needs to be etched. Although this method solves the problems of incomplete etching and easy short circuit of the circuit, in the drilling process, the orifice of the thin copper film is subjected to force, which will cause deformation of the orifice and abnormal wire drawing of the drilling, affecting the yield of the printed circuit board. The thin copper film requires a precision drill to work, which is costly. In addition, the precision drill can only drill holes in 2-3 stacked substrates each time, and the drilling efficiency is low.

[0038] In view of this, the present application provides a method for manufacturing a printed circuit board, which is to attach a protective film to the circuit metal layer of the raw material substrate, remove the protective film after drilling and micro-etching, obtain a front-end substrate, and then perform exposure, development and electroplating on the front-end substrate to obtain a printed circuit board. In this way, the protective film can protect the circuit metal layer of the raw material substrate during the drilling and micro-etching processes, solving the problems in the related art that the hole force of the thin copper film will cause the hole to deform and the drilling wire drawing to be abnormal, affecting the yield of the printed circuit board, and the thin copper film requires a precision drill bit to work, which is high in cost and low in drilling efficiency.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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:

[0043] Step 101, obtaining a raw material substrate, wherein a circuit metal layer is provided on the surface of the raw material substrate;

[0044] In one embodiment, the raw material substrate can 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, circuit metal layers are respectively arranged on both sides of the basic dielectric layer.

[0045] In one embodiment, the circuit metal layer may be a copper metal layer, a silver metal layer, etc. There is no specific limitation on the selection of the circuit metal and it can be set as needed.

[0046] In one embodiment, after obtaining the raw substrate, the raw 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.

[0047] Based on the above Figure 1 In the method flow, the embodiment of the present application provides a method for manufacturing a printed circuit board. In step 101, obtaining a raw material substrate includes:

[0048] The raw metal layer on the surface of the raw material substrate is reduced in thickness to less than 15 um, so as to obtain a raw material substrate having a circuit metal layer less than 15 um.

[0049] 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.

[0050] In one embodiment, the thickness of the circuit metal layer on the raw material substrate in the related art is usually greater than 15um, and the thickness of the circuit metal layer greater than 15um will result in incomplete metal etching during etching and circuit short circuit. Therefore, after obtaining the raw material substrate, the raw material metal layer on the raw material substrate is subjected to a thickness reduction process. The raw material metal layer is reduced to less than 15um, and a raw material substrate having a circuit metal layer less than 15um is obtained. Similarly, the smaller the thickness of the circuit metal layer, the cleaner the non-circuit part is etched in the circuit manufacturing process. Therefore, the circuit metal layer can be reduced to 2-3um or 3-4um. In this way, a protective film is subsequently attached to the raw material substrate to protect the circuit metal layer, which can not only ensure that the metal etching of the non-circuit part in the circuit manufacturing process is clean, but also ensure that the circuit metal layer at the orifice is not deformed and wiredrawn, and the process cost is low and the efficiency is high.

[0051] Step 102: affix a protective film on the surface of the circuit metal layer of the raw material substrate to obtain a film-attached substrate, and after drilling the film-attached substrate, remove the protective film on the surface of the film-attached substrate to obtain a front-end substrate.

[0052] In one embodiment, the protective film may be a metal film, such as a copper film, an aluminum film, an alloy film, etc. The metal film is attached to the circuit metal layer by glue or adhesive.

[0053] In one embodiment, the protective film can be an organic substance, an organic compound, etc., such as a resin, a photosensitive film. If it is a curable film, it can be attached to the circuit metal layer by glue or adhesive, or a thermosetting film, a photocurable film, etc., can be attached to the circuit metal layer by heating or exposure. Here, there is no specific restriction on the selection of the protective film, and it can be set as needed.

[0054] In one embodiment, if Figure 3 As shown, a double-sided substrate - a film substrate provided in an embodiment of the present application.

[0055] In one embodiment, if the protective film is attached to the circuit metal layer by glue or adhesive, the protective film on the circuit metal layer can be removed by using a dissolving agent, a solvent or heating. If the protective film is a thermosetting film, a photocuring film, etc., the protective film on the circuit metal layer can be removed by using a corresponding solvent. The material of the protective film and the combination of the protective film and the circuit metal layer can be set as needed, and there is no specific limitation here. For example, the photosensitive film and the corresponding solvent in the exposure and development process can be used.

[0056] Based on the above Figure 1 In the method flow, the embodiment of the present application provides a protective film and a method for using the same. In step 102, the protective film is a protective copper film, one side of the protective copper film is provided with a tearable adhesive, and the protective film is attached to the surface of the circuit metal layer of the raw substrate to obtain a film-attached substrate, including:

[0057] The protective copper film with a tearable adhesive side is pressed onto the surface of the circuit metal layer of the raw substrate, and roller pressing is performed to obtain a film-attached substrate.

[0058] In one embodiment, the protective copper film is 15-18um, and during the roller pressing process, the roller pressure is 4.5-5KG / cm 2 , the roller speed is 1.0-1.2m / min, and the roller temperature is 50-60℃.

[0059] In one embodiment, the protective copper film is 18-21um, and during the roller pressing process, the roller pressure is 5.5-6KG / cm 2 , roller speed 0.8-1.0m / min, roller temperature 60-70℃.

[0060] In one embodiment, the protective copper film is 18um, and during the roller pressing process, the roller pressure is 5KG / cm 2 , the roller speed is 1.0m / min, and the roller temperature is 60℃.

[0061] Based on the above Figure 1 The method flow and the protective film and the use method thereof are provided in the embodiment of the present application. A method for removing the protective film is provided. In step 102, the protective film attached to the surface of the film-attached substrate is removed to obtain a front-end substrate, including:

[0062] The protective film is removed from the surface of the film-attached substrate to obtain the front-stage substrate.

[0063] Step 103: Expose, develop and electroplate the front-end substrate to obtain a printed circuit board.

[0064] In one embodiment, the front-end substrate may be subjected to exposure, development, electroplating, film stripping, etching and other process treatments to obtain a printed circuit board. The process used for the front-end substrate is not specifically limited and can be set as needed.

[0065] In the above method, a protective film is attached to the surface of the circuit metal layer of the raw material substrate, and drilling is performed after the protective film is attached. After the drilling process, the attached protective film is removed. In this way, during the drilling process, since the protective film is attached to the circuit metal layer, when the drill bit is pulled up, the protective film replaces the thin circuit metal layer to bear force at the hole mouth, preventing the thin circuit metal layer at the hole mouth from deformation and wire drawing, so as to improve the yield of the printed circuit board, and since the protective film protects the thin circuit metal layer, an ordinary drill bit can be used for drilling, and the drilling cost is low. Therefore, the ordinary drill bit can work each time to drill more than three stacked substrates, and the drilling efficiency is high.

[0066] Based on the above Figure 1The present invention provides a method for manufacturing a printed circuit board. In step 102, after drilling the film substrate, the protective film on the surface of the film substrate is removed to obtain a front-end substrate, including:

[0067] After drilling and micro-etching the film substrate, the protective film on the surface of the film substrate is removed to obtain the front-end substrate. The micro-etching process is any one of copper plating, black hole and black shadow.

[0068] 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 metal of the circuit metal layer (if the metal of the circuit metal layer is copper, it can be plated with copper, 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.

[0069] Among them, the black hole process is to carbonize the inside of the hole so that the dielectric layer of the hole wall can 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 metal thickness of this process is designed according to the process. The main difference between the black shadow process and the black hole process is that the conductive layer of the black hole is carbon powder, and the conductive layer of the black shadow is graphite.

[0070] In one embodiment, the film substrate is micro-etched before the circuit manufacturing process. In order to ensure the reliability of the circuit connection and offset the poor circuit connection that may be caused by micro-etching, when the raw metal layer of the raw substrate is thickened, it is thickened to 3-4um to obtain a circuit metal layer with a thickness of 3-4um. For example, the micro-etching amount of the black shadow process is 1.5-2.0um, and the circuit metal layer with a thickness of 3-4um can offset the micro-etching of the black shadow process: 1.5-2.0um. The thickness of the circuit metal layer after micro-etching is greater than 1um, ensuring that the circuit metal layer at the opening does not leak the basic dielectric layer, ensuring the reliability of the circuit connection and the yield of the printed circuit board. In this way, preventing the too thin circuit metal layer from exposing the basic dielectric layer after micro-etching can prevent the phenomenon that the exposed basic dielectric layer cannot be plated with metal in the subsequent electroplating process, and the poor bonding between the plated metal and the circuit metal layer, thereby ensuring the reliability of the circuit connection.

[0071] Based on the above Figure 1 The present invention provides a method for manufacturing a printed circuit board, such as Figure 4 As shown, in step 103, the front-end substrate is subjected to exposure, development and electroplating treatment to obtain a printed circuit board, including:

[0072] Step 401: Based on the set circuit of the front-end substrate, the substrate film layer laid on the circuit metal layer is exposed and developed to expose the circuit metal layer corresponding to the set circuit.

[0073] Step 402, electroplating the metal exposed on the front-stage substrate to increase the thickness of the exposed metal to a preset metal thickness, thereby obtaining an intermediate circuit board, wherein the thickness of the substrate film layer is greater than the preset metal thickness;

[0074] Step 403: Perform film stripping and etching processing on the intermediate circuit board to obtain a printed circuit board.

[0075] In one embodiment, the set circuit may be a file containing circuits that need to be made on the circuit metal layer on the raw material substrate.

[0076] 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 5 As shown, after obtaining a raw material substrate with a circuit metal layer on the surface, the method includes:

[0077] Step a: affixing a protective film on the surface of the circuit metal layer of the raw material substrate to obtain a film-attached substrate.

[0078] Step b: drilling and micro-etching the film-attached substrate.

[0079] Step c: removing the protective film on the surface of the film-attached substrate to obtain a front-end substrate.

[0080] Step d, film laying: laying a substrate film layer (photosensitive film sensitive to ultraviolet rays) on the surface of the front substrate.

[0081] Step e, exposure: a photomask is set above the photosensitive film. Based on the set circuit design, the circuit part of the photomask 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.

[0082] Step f, development: Then use a developing solution to dissolve the photosensitive film portion corresponding to the opaque portion of the photomask, exposing the circuit metal layer of the circuit portion.

[0083] Step g, electroplating: then electroplating is performed on the front-end substrate with the exposed part of the circuit metal layer, and metal of a preset metal thickness is electroplated on the exposed circuit metal layer to thicken the exposed metal by the preset metal thickness to obtain an intermediate circuit board.

[0084] Step h, film stripping: For the obtained intermediate circuit board, use a high-performance film stripping solution to strip and clean the intermediate circuit board. Note that it is necessary to ensure that the film is stripped cleanly during this process.

[0085] Step i, etching: using etching process (if the circuit metal layer is a copper film, copper reduction process can also be used), the circuit metal layer on the intermediate circuit board after film removal is uniformly etched to a certain thickness to obtain an intermediate circuit board with a set circuit pattern, and then double-sided board 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 the same as the conventional rigid circuit board or flexible circuit board process, and follow-up design needs to be made. There is no specific restriction on the process of the back-end process here, and it can be set as needed.

[0086] Among them, the etching thickness is the thickness of the circuit metal layer, so as to etch away the specific metal of the non-circuit part on the intermediate circuit board. In order to ensure clean etching, the etching thickness can be set to be greater than the thickness of the circuit metal layer. Correspondingly, in order to ensure that the original circuit metal layer thickness of the substrate + the preset metal thickness of the electroplating meets the circuit thickness (set metal thickness) requirement, during electroplating, the preset metal thickness of the electroplating can make the thickness of the original circuit metal layer thickness of the substrate + the preset metal thickness exceed the circuit thickness requirement. The excess thickness can be used to offset the etching when etching the specific metal of the non-circuit part of the substrate.

[0087] In one embodiment, the thickness of the substrate film layer laid on the raw material substrate is greater than the preset metal thickness of the electroplating, such as Figure 5 As shown in step g, this ensures that when the metal of the preset 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 preset metal thickness of the electroplating can be set according to the process requirements, and there is no specific limitation here.

[0088] In one embodiment, in the above-mentioned manufacturing methods of each printed circuit board and related embodiments, the preset metal thickness is 15um-18um or 18-19um, and the substrate film thickness is 19-20um or 20-21um. The preset metal thickness can be selected to be around 18um.

[0089] Based on the above-mentioned manufacturing methods and related embodiments of printed circuit boards, the present application provides a method for manufacturing a printed circuit board, taking the double-sided circuit metal layer of the raw material substrate as an example, wherein the metal of the circuit metal layer is copper. Figure 6 As shown, including:

[0090] Step 601, thinning process: reducing the thickness of the original copper film on both sides of the raw material substrate to less than 15 um, to obtain a raw material substrate with a copper film thickness of less than 15 um on both sides.

[0091] Here, if the raw metal layer is copper, a copper reduction process can be used to reduce the copper thickness of the raw substrate 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 raw substrate copper is, the more conducive it is 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 raw substrate copper thickness obtained based on the raw substrate before electroplating is 2-3um.

[0092] If a black hole process or a black shadow process is required, the copper needs to be micro-etched 1.0um according to the black hole process or the black shadow process, so the copper thickness of the copper reduction control is controlled to 3-4um, that is, the thickness of the circuit metal layer on the surface of the raw material substrate is 3-4um, and the copper is micro-etched 1.0um before the circuit manufacturing process, and the thickness of the remaining circuit metal layer is 2-3um, and then enters the subsequent circuit manufacturing process. Here, the material factory can also be directly required 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.

[0093] Step 602: A protective film is attached to the surface of the circuit metal layer of the raw material substrate to obtain a film-attached substrate.

[0094] In one embodiment, in step (1), a removable adhesive is attached to the protective film (single-sided protective copper film with a thickness of 18 um). The protective film can be placed in a roll.

[0095] Step (2), attach the protective copper film RTR (roll-to-roll, RTR process in the current circuit board manufacturing process) with a tearable adhesive to the 3um circuit metal layer-copper film material.

[0096] Step (3), through roller pressing, the 18um protective copper film and the 3um circuit metal layer-copper film material are tightly attached to each other, and the 3um circuit metal layer-copper film material is transformed into a 21um thick film substrate (i.e., a conventional raw material substrate or a conventional double-sided board).

[0097] Among them, in the RTR protective copper film process, an 18um single-sided tearable protective copper film is applied to the front and back sides of the 3um circuit metal layer-copper film material, and then the roller pressure is 5KG / cm 2 , roller speed 1.0m / min, roller temperature: 60℃; after roller lamination, the 3um circuit metal layer-copper film material is turned into a 21um thick film substrate (ie, a conventional raw material substrate or a conventional double-sided board).

[0098] Step (4), after lamination, the film substrate (i.e., conventional raw material substrate or conventional double-sided board) is further subjected to drilling and micro-etching processes. After the micro-etching process is completed, the protective copper films on both sides are torn off, and then the subsequent circuit manufacturing process and subsequent process flows are completed.

[0099] Step 603, drilling process: using the through holes obtained by drilling to connect the circuits on both sides of the substrate.

[0100] In one embodiment, if there is a circuit layer inside the raw substrate, that is, the printed circuit board made using the raw substrate is a multi-layer circuit board, the drilled holes may also include buried holes to connect the circuit inside the raw substrate with the external circuit.

[0101] In one embodiment, the drilled holes may also include mounting holes.

[0102] In one embodiment, if there is no circuit inside the raw material substrate, it can be used as an inner core board to make a multi-layer circuit board. The specific process flow and type of printed circuit board are not limited here and can be set as needed.

[0103] Among them, in the mechanical drilling process, after the protective copper film process, the 3um circuit metal layer thin copper material is changed to a conventional circuit metal layer thickness of 21um, and a conventional drill bit can be used for mechanical drilling. In this way, conventional drill bits are used instead of precision drill bits, reducing costs. And each drilling can be set up with 8-10 layers to improve efficiency. In addition, after the protective copper film is applied, even if the drilling hole is deformed, it is the surface of the protective copper film that is deformed, which does not affect the hole shape of the circuit metal layer thin copper material, thereby improving the yield.

[0104] Step 604, black shadow process: carbonization treatment in the through hole allows the basic dielectric layer of 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.

[0105] Among them, in the black shadow process: because of the 18um protective copper film, the copper thickness of the hole becomes 21um. Even after the black shadow micro-etching amount of 2um, the hole can be protected from exposing the basic dielectric layer, thereby improving the yield.

[0106] Step 605: remove the protective film attached to the surface of the film-attached substrate to obtain a front-end substrate.

[0107] Among them, the protective copper film tearing process requires tearing off the protective copper film on both sides after the mechanical drilling process and micro-etching process for subsequent circuit manufacturing process.

[0108] Step 606, film laying process (dry film pasting process): a dry film (substrate film layer) with a thickness of 20um is pasted on the front substrate (if a flexible printed circuit board is manufactured, the front substrate is a flexible board, if a rigid printed circuit board is manufactured, the front substrate is a rigid 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.

[0109] 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.

[0110] Step 607, exposure process: using an exposure machine (laser direct imaging, LDI) to expose the non-circuit part, so that the dry film in the non-circuit part reacts and adheres closely to the surface of the circuit metal layer.

[0111] 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.

[0112] Step 608, development process: using a developing solution to dissolve and clean the dry film of the circuit part to develop a pattern on the front-end 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.

[0113] Afterwards, the front-end 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 boxes to the next process to reduce exposure and avoid dust on the board causing poor circuit electroplating.

[0114] Step 609, electroplating process: calculate the electroplating parameters according to the electroplating area of ​​the designed film pattern, and perform pattern electroplating on the front-end substrate; after the electroplating is completed, the circuit copper is directly electroplated on the copper surface of the front-end substrate circuit to obtain the intermediate circuit board, and the electroplated copper thickness can be 18um.

[0115] Step 610, 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 intermediate circuit board after electroplating.

[0116] Step 611, etching process: Use copper reduction line or etching line to control the parameters of uniformly etching 3-4um copper thickness on the middle circuit board, etch the low copper (specific metal layer of the non-circuit part on the middle circuit board) cleanly, and make a circuit pattern.

[0117] Step 612, post-process technology: after double-sided board cleaning, covering film pasting, lamination, curing, surface treatment, lamination and reinforcement, characterization, curing, shape process, electrical testing process, inspection process, etc., a printed circuit board is obtained.

[0118] It should be noted that the process steps of the above-mentioned method for manufacturing a printed circuit board are not unique. For example, there may be a cleaning process after step 608. If the printed circuit board is a multi-layer circuit board, and the obtained intermediate circuit board is an inner core board, then at least one matching core board corresponding to the inner core board may be obtained (the matching core board may be obtained by the same process as the inner core board, and the circuits thereon match the circuits of the inner core board and can connect electronic components to achieve certain functions). The inner core board and at least one matching core board are pressed together to obtain a basic multi-layer board. The surface of the basic multi-layer board has a surface circuit metal layer, that is, in appearance, the basic multi-layer board is the same as the raw material substrate, and both have a circuit metal layer. Then, the basic multi-layer board is subjected to the same manufacturing process as the inner core board to obtain a final printed circuit board with multi-layer circuits. Afterwards, components are mounted on the printed circuit board.

[0119] Based on the above Figure 1 , Figure 4 , Figure 5 , Figure 6 The present invention provides a method for manufacturing a printed circuit board and its corresponding embodiments. The embodiment of the present application provides a printed circuit board, which can be a printed circuit board using Figure 1 , Figure 4 , Figure 5 , Figure 6 The method for manufacturing any printed circuit board in the corresponding embodiments is obtained.

[0120] Those skilled in the art will understand that Figure 5 The process flow and corresponding structure shown in the figure do not constitute a limitation on the method for manufacturing a printed circuit board and the printed circuit board structure obtained therefrom, and may include more or fewer process steps and structures than those shown in the figure. It can be understood that without departing from the conceptual scope of the method for manufacturing a printed circuit board and the printed circuit board obtained therefrom provided in the embodiment of the present application, all simple deformation schemes (including replacement of equivalent process steps, reduction or addition of conventional process steps, replacement of equivalent materials and replacement of equivalent structures, etc.) should be within the protection scope of the present application.

Claims

1. A method for manufacturing a printed circuit board, characterized in that: include: Obtaining a raw material substrate, wherein a circuit metal layer is provided on the surface of the raw material substrate; A protective film is attached to the surface of the circuit metal layer of the raw substrate to obtain a film-attached substrate, and after drilling the film-attached substrate, the protective film attached to the surface of the film-attached substrate is removed to obtain a front-end substrate; The front-end substrate is subjected to exposure, development and electroplating treatments to obtain a printed circuit board.

2. The circuit according to claim 1, characterized in that After drilling the film-attached substrate, removing the protective film attached to the surface of the film-attached substrate to obtain a front-end substrate includes: After the film-attached substrate is subjected to the drilling and micro-etching treatments, the protective film attached to the surface of the film-attached substrate is removed to obtain the front-end substrate, and the micro-etching treatment is any one of copper plating, black hole and black shadow processes.

3. The circuit according to claim 1, characterized in that The obtaining of the raw material substrate comprises: The raw metal layer on the surface of the raw material substrate is reduced in thickness to less than 15 um, so as to obtain the raw material substrate having the circuit metal layer less than 15 um.

4. The circuit according to claim 3, characterized in that The thickness of the circuit metal layer is 2-3um or 3-4um.

5. The circuit according to claim 1, characterized in that The protective film is a protective copper film, one side of the protective copper film is provided with a tearable adhesive, and the protective film is attached to the surface of the circuit metal layer of the raw substrate to obtain a film-attached substrate, comprising: The protective copper film having a tearable adhesive surface is pressed onto the surface of the circuit metal layer of the raw material substrate, and roller pressing is performed to obtain the film-attached substrate.

6. The circuit according to claim 5, characterized in that The protective copper film is 15-18um or 18-21um; in the roller pressing process, the roller pressure is 4.5-5KG / cm 2 or 5.5-6KG / cm 2 , the roller speed is 0.8-1.0m / min or 1.0-1.2m / min, and the roller temperature is 50-60℃ or 60-70℃.

7. The circuit according to claim 5, characterized in that The step of removing the protective film attached to the surface of the film-attached substrate to obtain a front-end substrate comprises: The protective film is torn off from the surface of the film-attached substrate to obtain the front-stage substrate.

8. The circuit according to claim 1, characterized in that The step of performing exposure, development and electroplating on the front-end substrate to obtain a printed circuit board comprises: Based on the set circuit of the front-end substrate, the substrate film layer laid on the circuit metal layer is exposed and developed to expose the circuit metal layer corresponding to the set circuit; Electroplating the metal exposed on the front-stage substrate to increase the thickness of the exposed metal to a preset metal thickness, thereby obtaining an intermediate circuit board, wherein the thickness of the substrate film layer is greater than the preset metal thickness; The intermediate circuit board is subjected to film stripping and etching treatment to obtain a printed circuit board.

9. The circuit according to any one of claims 1 to 8, characterized in that The preset metal thickness is 15um-18um or 18-19um, and the substrate film layer thickness is 19-20um or 20-21um.

10. A printed circuit board, characterized in that: The printed circuit board is obtained by the method for manufacturing the printed circuit board according to any one of claims 1 to 9.

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