阅读说明：本技术 选择性电镀孔，激光制抗镀图案，图形电镀蚀刻的制造电路板方法 (Method for manufacturing circuit board by selective electroplating of holes, laser-made plating-resistant pattern and pattern electroplating etching ) 是由 胡宏宇 刘天宇 于 2021-08-30 设计创作，主要内容包括：本发明涉及一种选择性电镀孔,激光制抗镀图案,图形电镀蚀刻的制造电路板方法,用一种表面疏化学镀活性种子并且抗电镀、抗蚀刻的高聚物薄膜掩蔽覆铜箔板；钻孔并只在孔壁上沉积金属,根据图形尺寸改变光斑直径,激光分步和分别去除线路区域、非线路区域、焊接区域薄膜掩蔽材料制造抗电镀图案、抗蚀刻图案和阻焊图案。本发明用非光敏薄膜抗电镀薄膜掩蔽板表面,可只在孔壁上沉积金属,电路板金属化孔质量更好；激光光斑直径根据图案尺寸改变,去除掩蔽材料速度快、一致性好；激光分步制造图案,可以有区别地电镀孔壁,以及焊盘和线路,控制镀层厚度容易,电路板更好地满足电气要求。(The invention relates to a method for manufacturing a circuit board by selectively electroplating holes, making anti-plating patterns by laser and electroplating and etching patterns, wherein a high polymer film with a sparse chemical plating active seed on the surface and anti-plating and anti-etching is used for masking a copper-clad plate; drilling holes and depositing metal on the hole walls, changing the diameter of a light spot according to the size of the graph, and removing the film masking materials of a circuit area, a non-circuit area and a welding area step by laser to manufacture an anti-electroplating pattern, an anti-etching pattern and a solder resist pattern. According to the invention, the surface of the plate is masked by the non-photosensitive anti-electroplating film, metal can be deposited on the hole wall only, and the quality of the metallized hole of the circuit board is better; the diameter of the laser spot is changed according to the size of the pattern, and the masking material removing speed is high and the consistency is good; the laser step-by-step manufacturing pattern can differentially electroplate the hole wall, the bonding pad and the circuit, the thickness of the plating layer is easy to control, and the circuit board can better meet the electrical requirement.)

1. A method for manufacturing a circuit board by selectively electroplating holes, making plating-resistant patterns by laser and electroplating and etching the patterns is characterized by comprising the following steps of: masking the copper-clad plate by using a high polymer film with the surface sparse and chemically plated with active seeds and with electroplating resistance and etching resistance; drilling holes and depositing metal on hole walls, changing the diameter of a light spot according to the size of a graph, and removing high polymer film masking materials in a line area, a non-line area and a welding area respectively by laser step by step to manufacture an anti-electroplating pattern, an anti-etching pattern and a solder-resisting pattern, wherein the specific processing steps are as follows:

(1) attaching a high polymer film with the surface thinned with chemical plating active seeds and electroplating resistance and etching resistance to the surface of a workpiece which is not internally provided with or contains one or more layers of conductive patterns and is coated with copper foil on two sides;

(2) drilling according to the design requirement;

(3) conducting electricity through the holes;

(4) electroplating, namely depositing copper on the hole wall to thicken the hole wall;

(5) removing the high polymer film masking layer on the bonding pad and the circuit by laser;

(6) electroplating, namely depositing copper on the bonding pad, the circuit and the hole wall to thicken;

(7) electroplating, namely depositing a corrosion-resistant metal protective layer on the bonding pad, the circuit and the hole wall;

(8) removing the high polymer film masking layer in the non-line area by laser;

(9) etching and removing the copper foil layer on the non-circuit area and in the area which is not covered by the corrosion-resistant metal protective layer;

(10) carrying out electrical on-off inspection on the circuit board;

(11) removing the corrosion-resistant metal protective layer on the bonding pad, the circuit and the hole wall;

(12) coating the whole board and curing the solder resist material at one time;

(13) removing the solder resist material layer on the surface of the welding area by laser at an assembly site to manufacture a solder resist pattern, and cleaning and performing weldability treatment on the surface of the welding area;

(14) adding solder to the connecting disc, carrying out component mounting and insertion, and carrying out remelting welding or wave soldering.

2. The method of claim 1, wherein: the surface sparse electroless plating active seed and electroplating and etching resistant high polymer film material comprises a dry PET, PI, RPP, BOPET, BOPP, PA, PPE and parylene high polymer film made of single-component, multi-component, composite thermosetting, photo-curing, hot-pressing adhesive, non-photosensitive and photosensitive materials, and a monomeric, prepolymerized or polymerized liquid and paste form material; the coating method of the material comprises one or more of rolling, hot pressing, printing, plating, spraying and curtain coating; the thickness of the material is greater than the total metal thickness thickened on the line, and the range is 2-3000 μm.

3. The method of claim 1, wherein: the equipment adopted by the laser removal can convert the diameter of a light spot interacted with the material on line by taking energy and power on a unit area as constant quantities according to a circuit graph structure; the device comprises one or more sets of data acquisition and processing systems, an equipment operation system, a laser light source, a light beam shaping and transmission system, a laser focusing system, a workpiece clamping and automatic and manual feeding and discharging system, a workpiece positioning and movement and control system with light beams, a visual detection and laser power monitoring and compensation system, a cleaning and constant temperature system, wherein the types of the light beams comprise Gaussian, flat-top, annular, Bessel and multi-point nanosecond ultraviolet wavelength lasers, picosecond and femtosecond laser beams.

4. The method of claim 1, wherein: and (2) the step of drilling according to the design requirement is to adopt laser to control the drilling depth to manufacture a conducting layer in the hole and a step protruding from the insulating layer below the conducting layer, a conducting layer connecting disc is generated in the hole, the protruding values of the conducting layer and the insulating layer below the conducting layer are 0-50 mu m, and the hole shape comprises a cylinder and a cone.

5. The method of claim 1, wherein: the hole electroconducting in the step (3) comprises a chemical copper deposition process of forming an initial conducting layer through activation of deposited colloidal palladium and chemical copper plating; also comprises a diameter electroplating process for directly forming an initial conductive layer by depositing carbon black, graphite, colloidal palladium and ionic palladium in the hole and using conductive polymers; comprises physically brushing, wiping, grinding or chemically removing the residual active conductive active material on the surface of the plate after direct electroplating or before electroless copper plating after activation.

6. The method of claim 1, wherein: after the step (1) is carried out, before or after the steps (2) and (3) are carried out, before the step (4) is carried out, laser is used for removing dead copper areas without electrical functions, which are not lines and have an interval of more than 30 mu m with the lines, or areas, the conductive layers of which need to be removed and do not have negative influence on the subsequent removal process, or areas, the functions of which are not influenced by the copper thickness, or areas, the functions of which are positively influenced by the copper thickness, of which are added with anti-electroplating film masking layers, so that copper foil surfaces below the areas are exposed, and dispersed patterns which are favorable for the balanced distribution of electroplating current when the hole walls are electroplated are formed.

7. The method of claim 1 or 3 or 4 or 6, wherein: the steps (2), (5), (8) and (13) comprise using the laser with the same wavelength and pulse width and the laser with different wavelengths and pulse widths, and completing the steps under the parameters of different spot diameters, focal depths, different optical power densities and the like; when only organic material is removed, the focused laser optical power density used is maintained greater than the minimum power density required to remove the organic material.

8. The method of claim 1 or 3 or 4 or 6 or 7, wherein: and (2), (5), (8) and (13) generating processing data by taking the spot diameter as a variable, taking the processing speed as a priority, controlling the overlapping quantity when the adjacent processing paths and the adjacent spot action areas of the same processing path are overlapped as a constraint condition and taking the laser energy projected on a unit area and the laser power on the unit area as constant quantities according to the geometric shape and the size of each pattern in the processed task and the corresponding relation between the pattern width and the spot diameter.

Technical Field

The invention belongs to the technical field of circuit manufacturing, relates to a laser processing technology, and particularly relates to a method for manufacturing a circuit board by selectively electroplating holes, preparing plating-resistant patterns by laser and electroplating and etching patterns.

Background

The invention utilizes laser processing technology, uses the high polymer film with the same surface sparse chemical plating active seeds as a masking layer, respectively manufactures only electroplating hole walls and electroplating-resistant patterns of simultaneously electroplating hole walls and lines by removing and processing through laser step-by-step photoetching, respectively controls hole wall copper thickness and line copper thickness to manufacture circuit boards, can better meet the electrical requirements of electronic products on the circuit boards, is particularly suitable for manufacturing thick copper conductive patterns, and is also suitable for the production of various circuit boards in large batch, small batch, multiple varieties and samples.

The manufacturing process comprises the following steps: coating a high polymer film on the surface of a double-sided copper-clad plate or a multilayer circuit board which finishes the manufacture of an inner layer and an overlapped outer layer → drilling → hole conduction → copper electroplating thickening pore wall → laser removal of a high polymer film exposed pad and circuit copper → copper electroplating thickening → electroplating of corrosion resistant metal → laser removal of a film exposed non-circuit area copper → etching → on-off inspection → removal of metal resist → solder mask adhesion → assembly of a laser solder mask pattern for field assembly and solderability treatment of a welding area → solder paste omission, and component mounting and welding are carried out.

In the world today, electronic products are ubiquitous. One of the most important parts of electronic products is a circuit board which is an electrical connection channel among all components and determines respective electrical parameters and electrical logic relations; meanwhile, the mounting and fixing carrier is a mounting and fixing carrier of each component and is a framework of a product. The electric connection channel is realized by a conductive pattern and a metallized hole, the quality of element installation and fixation is closely related to the quality of a solder resist pattern and the weldability of a welding area, and the main production process of the circuit board also expands around the solderability of the conductive pattern, the metallized hole, the solder resist pattern and the welding area. However, in the conventional method for manufacturing the circuit board, the conductive pattern and the solder resist pattern are manufactured by pattern transfer, and the metallized holes are manufactured by using a copper foil substrate, which is an indirect technology essentially and cannot meet the requirements of an electronic technology on pattern precision and hole quality.

Spatially, the electrical connections on the circuit board can be divided into two groups: connections in the horizontal direction, i.e. parts commonly referred to as conductive patterns, are above the plane of the layers for making connections in the direction X, Y; connections in the vertical direction, made by metallized holes, pass through the insulating layer and the conductive layer in the Z-direction for making electrical interconnections between layers of the conductive pattern. In the conventional circuit board manufacturing technology, a conductive pattern in the horizontal direction is manufactured mainly by a subtractive method, that is: removing the redundant copper foil on the copper clad laminate, and using the remained copper foil as a conductive pattern as a part with an electrical connection function, such as a lead, a bonding pad and the like; the electrical interconnections between layers in the vertical direction are made predominantly by additive methods, namely: and adding conductive materials to the hole walls in the holes, and enabling the conductive hole walls to penetrate through the metal layers in the horizontal direction to realize electrical interconnection.

As an important link in the electrical connection link, in the process of manufacturing the circuit board, the thicknesses of the conductive pattern in the X, Y direction and the conductive layer on the hole wall in the Z direction should be separately controlled, so that the whole electrical channel meets the electrical requirements of the product, and particularly, the thickness of the conductive layer on the hole wall should be independently controlled, so that the conductive layer does not become a weak link in the connection link. However, in the general circuit board technology, the control of the hole wall copper thickness and the control of the line copper thickness interfere with each other, and the trade-off between the two has to be carried out, which is one of the problems affecting the electrical performance and reliability of the circuit board.

The holes are metallized, typically chemically. Firstly, depositing a thin conductive material layer on the insulated hole wall by chemical plating or other means; on the initial conductive layer, a conductive metal is plated by electroplating to a desired thickness so that holes through the metal layer have a reliable electrical interconnection index between layers. Different process routes are derived based on different hole metallization technologies, including a hole masking method, a pattern electroplating etching method, and the like. The two process routes have advantages and disadvantages respectively, and the technical scheme and the key technology are briefly described as follows:

the pattern electroplating etching method, known as the reverse plating method, is a classic process route for manufacturing printed boards. The process after cutting starts from drilling and hole metallization, an initial conductive layer is formed on the hole wall by a chemical plating or direct electroplating method, metal copper is deposited on the hole wall and the plate surface to a certain thickness by an electroplating method, then pattern transfer is carried out, a layer of organic material thin layer, namely plating resist, is firstly used for masking the copper foil of the non-circuit part by photosensitive film pasting, exposure and development, and the surfaces of the circuit part, including a lead, a bonding pad, the hole wall and the like, are exposed. Therefore, the surface of the metal copper to be removed is masked, and is not contacted with the liquid medicine in the electroplating process, so that the metal is not continuously deposited; the part needing to be reserved, including the surface of the conducting wire, the bonding pad and the hole wall, is exposed outside and is contacted with the liquid medicine during electroplating, or copper is continuously electroplated firstly, or corrosion-resistant metal such as tin, tin-lead alloy, nickel, gold and the like are directly electroplated. And then removing the organic material masking layer to expose the copper foil of the non-circuit part, enabling the copper foil to react with an etchant in the etching process, dissolving the copper foil into a liquid medicine after oxidation, and enabling the copper foil to disappear from the plate surface, wherein the surfaces of the circuit parts such as the wires, the bonding pads, the hole walls and the like are shielded by a metal resist and are not contacted with the etchant, and the metal resist is remained on the plate to form a required conductive pattern. Finally, to make a solder resist pattern on the non-soldering area of the circuit board, a solderable material is applied over the area of the soldering area.

The circuit board is manufactured by the reverse plating method, is mature and stable, has multiple working procedures and complex operation, and can carry out electroplating treatment on the circuit part and the non-circuit part in a distinguishing way. After the initial conductive layer is formed by the hole metallization, depositing copper on the hole wall by an electroplating method for one time until the required final thickness is reached, and meanwhile, increasing the thickness of the copper conductive layer on the rest part of the board surface is called as a full-board electroplating etching method; after the hole is metallized, a thin layer of copper is electroplated on the hole wall and the board surface, the copper thickness is controlled to be just resistant to the subsequent process, and after the pattern is transferred, the copper electroplating is carried out to the required final thickness, namely, the conductive pattern part is only plated with thicker copper, and the non-conductive pattern part is plated with thinner copper.

The hole masking method is another common circuit board manufacturing process route. The process after cutting starts from drilling and hole metallization, an initial conductive layer is formed on the hole wall by a chemical plating or direct electroplating method, and metal copper is continuously deposited on the hole wall and the plate surface to the final required thickness by the electroplating method. Then, pattern transfer is performed, and the circuit portion including the conductive lines, pads, and holes is masked with a thin layer of an organic material called resist by attaching a photosensitive film, exposing, developing, and exposing the copper foil of the non-circuit portion. In the following etching process, the exposed non-circuit part of the surface of the copper foil contacts with the etchant to generate oxidation reaction, the dissolved medicine liquid disappears from the plate surface, and the surfaces of the circuit parts such as the conducting wire, the bonding pad, the hole wall and the like are not contacted with the etchant because of being shielded by the resist, and are remained on the plate to form the required conductive pattern. Like the reverse plating method, the via masking method also finally produces a solder resist pattern on the non-soldering area of the circuit board, and applies a solderable material on the soldering area. The hole masking process is characterized in that the whole board is electroplated with thickened copper, so that the process is relatively simple, but when the conductive pattern is manufactured, the process is more unfavorable for the production of a fine circuit structure because the thicker copper foil needs to be etched.

In the two process routes now commonly used, the process of making Z-connections by hole metallization can be divided into two stages: the method comprises the steps of manufacturing an initial conducting layer on an insulated hole wall and electroplating and thickening the conducting layer on the hole wall.

The technology for manufacturing the initial conducting layer can be divided into two methods of chemical copper plating and direct electroplating. The chemical copper plating, also called chemical copper deposition, has relatively complex process, is more mature, stable and wide in application range, and utilizes a self-catalytic oxidation-reduction reaction to deposit copper (Cu) in chemical copper plating solution on the hole wall²⁺) The ions are reduced into Cu, and the reduced metal copper crystal nucleus itself becomes a catalyst of other copper ions in the solution, so that the reduction reaction of copper is continued on the surface of the new copper crystal nucleus, and finally a thin layer of metal copper layer is formed on the insulated hole wall. Compared with the chemical copper plating technology, the direct electroplating technology has the advantages of simple process and environment friendliness, three methods of a carbon membrane method, a palladium membrane method and a high polymer membrane are popular, conductive carbon, palladium or high polymer materials are directly coated or manufactured on the hole wall, and after a continuous thin layer is formed, a basic conductive membrane is provided for subsequent electroplating deposition.

From the technical realization, the economy and the electrical performance, the speed of forming the conductive layer by the direct electroplating and chemical copper deposition technology is slow, the physical property is poor, and the requirements of the electronic product on the conductive performance and the mechanical performance of the Z-direction link section cannot be met, so that after the thin-layer conductive object is in a continuous state and the thickness and the strength can endure the subsequent processing in the processing process, the electroplating technology is switched to the circuit board production, and the metal copper with better performance is continuously added on the hole wall by the power of an external power supply. As mentioned above, there are two alternative routes of full-plate electroplating and pattern electroplating, and although the difference between the two technologies is that the thickening range of electroplating copper is different, in essence, the important purpose of both technologies is to electroplate copper on the hole wall, and to electroplate copper on the hole wall, the original copper foil on the substrate has to be used as the power line for plating copper on the hole wall, from this viewpoint, the conductive pattern on the X, Y plane only plays a role of plating.

Analyzing the results of the current plating of the Z-direction link with the X, Y conductive pattern, it can be seen that the current technology will limit the improvement of the Z-direction link machine and the electrical performance, and also cause the difficulty of the subsequent conductive pattern manufacturing process, which affects the precision and the manufacturing cost of the whole circuit board.

First, comparing X, Y plane and Z-direction conductive layer, it can be seen that neither full-board plating nor pattern plating really solves the problem that the thickness of Z-direction conductive layer is consistent with that of X, Y direction conductive layer in the circuit board connection link, and the thickness difference between the hole wall conductive layer forming Z-direction link and the plate surface conductive layer forming X, Y link is also enlarged in the process of electroplating and thickening the initial conductive layer. Because, on the X, Y plane, the conducting layer is based on the inherent conductive copper foil on the base plate, the above-mentioned electroplating copper thickens the conducting layer of the hole wall, and also on the basis of the inherent copper foil on the plate surface, the thickness of the conducting layer is synchronously increased with the hole wall, and moreover, because of the factor of the power line step by step, and also because of the limitation of the depth capability and the uniform plating capability of the electroplating process, the thickness of the plate surface deposition layer is larger than that of the hole wall deposition layer. This runs counter to the increasing performance requirements of current and future electronic products for circuit board electrical connections, and in particular for Z-links. Therefore, it is necessary to develop a technique for selectively plating a thickened hole.

Secondly, the copper foil on the surface of the manufactured board and the copper foil on the surface of the original insulating substrate after the pattern electroplating and the full-board electroplating are analyzed, so that the thickness of the copper foil is increased, and the quality is deteriorated. In IPC standard IPC-6012, there are specific requirements on the wall thickness of the metallized holes, at least 20 μm. The current circuit board manufacturing process has limited deep plating capability, when the hole wall copper thickness reaches 20 microns, the copper thickness increased by the board surface exceeds the hole wall copper thickness, and after the added copper thickness is added with the original copper foil thickness of 18 microns, the total copper thickness exceeds 40 microns. Therefore, the conductive layer generated in the circuit board copper electroplating process becomes the top layer of the conductive layer of the future conductive pattern, and is the main medium for transmitting electrical signals with higher frequency under the action of the skin effect. However, it must be seen that the quality of the copper layer deposited by electroplating in the production of circuit boards is slightly lower than the purity of the original copper foil produced by electroforming or calendering, the crystal is slightly rough, and the quality of electrical and mechanical properties is slightly poor, in this sense, the increase of the thickness of the conductive layer is unfavorable for signal transmission. Therefore, it is necessary to develop a technique for independently plating an additional hole wall conductive layer without using the conductive pattern on the X, Y surface as a power supply line.

Furthermore, current circuit board production techniques, either pattern plating or full-plate plating, add a copper plating layer up to 25 μm thick based on the original copper foil material. The result of such hole metallization techniques, of course, greatly increases the difficulty of the process of manufacturing the conductive patterns. In the conventional technology, a conductive pattern is manufactured by using a chemical etching technology, an etching solution is contacted with a copper foil to perform etching in the processing process, the etching is performed in the depth direction of the copper foil, and the etching is performed in two lateral directions of a lead due to the contact of the etching solution and two side surfaces of the lead. The thicker and longer the copper layer is etched, the more severe the lateral etching phenomenon, which not only reduces the width of the conductive line but also causes disconnection when severe, and thus the thickness of the copper foil and the resulting lateral etching are a factor in the production of the fineness of the conductive pattern. In this regard, in order to manufacture a more precise conductive pattern, it is necessary to develop a technique for reducing the difficulty of manufacturing the conductive pattern by etching without increasing the thickness of the copper foil on the X, Y side.

In addition, in general, the conventional circuit board manufacturing technology, whether manufacturing conductive patterns on X, Y planes or solder resist patterns, has the problems of high precision and manufacturing difficulty, belongs to Transfer manufacturing technology/Transfer Process, and aims to achieve design by using mask master-mold and intermediate material Indirect Processing/Indirect Processing. In the existing technology, photo-drawing is needed to manufacture a corrosion-resistant pattern, an anti-electroplating pattern and a solder-resistant pattern to be used as a mold and connected in series, and errors and defects of a single mold and a single procedure can be amplified in subsequent processing procedures, so that the existing circuit board technology is difficult to manufacture fine products. In the existing technical system, dry films, metal resists, scaling powders for hot air leveling and the like used for the pattern transfer process are not materials required by the mechanical and electrical properties of the circuit board, and are not finally present on the product, but technical materials adopted for realizing the processing target are also required to be removed after the intermediate transition function is performed, and the materials are used and removed, so that equipment such as photo-painting, film pasting, exposure, development, etching, film removal and the like are required, so that the traditional circuit board technology has a complex manufacturing process, not only occupies capital and sites, but also wastes resources such as materials and equipment, and increases the manufacturing difficulty. In addition, in the conventional techniques, the conductive pattern and the solder resist pattern are generated in the transfer process of the resist pattern and the plating resist pattern formed by the intermediate material and the mold, and most of them are required to be performed in water or chemical solution, and waste residue, waste liquid, and waste gas are generated, which causes a large environmental stress. Therefore, it is necessary to develop a technology mainly based on direct processing, which replaces the existing indirect processing technology with common materials instead of special materials, with no or little intermediate equipment, which is another object of the present invention.

Disclosure of Invention

Aiming at the defect that thickened holes and circuits cannot be electroplated respectively in the prior art, the invention develops a novel manufacturing method which can differentially electroplate hole walls and circuits, a high polymer film with sparse chemical plating active seeds on the surface is used for masking a board surface, after drilling, only the hole walls are electroplated until the thickness meets the requirement, then laser is used for directly removing materials, patterns of the electroplated hole walls and circuits are manufactured, a pattern electroplating etching method is used for manufacturing conductive patterns, and finally, laser is used for directly removing materials to manufacture solder resist patterns.

The specific processing steps are as follows:

(1) attaching a high polymer film with the surface thinned with chemical plating active seeds and electroplating resistance and etching resistance to the surface of a workpiece which is not internally provided with or contains one or more layers of conductive patterns and is coated with copper foil on two sides;

(2) drilling according to the design requirement;

(3) conducting electricity through the holes;

(4) electroplating, namely depositing copper on the hole wall to thicken the hole wall;

(5) removing the high polymer film masking layer on the bonding pad and the circuit by laser;

(6) electroplating, namely depositing copper on the bonding pad, the circuit and the hole wall to thicken;

(7) electroplating, namely depositing a corrosion-resistant metal protective layer on the bonding pad, the circuit and the hole wall;

(8) removing the high polymer film masking layer in the non-line area by laser;

(9) etching and removing the copper foil layer on the non-circuit area and in the area which is not covered by the corrosion-resistant metal protective layer;

(10) carrying out electrical on-off inspection on the circuit board;

(11) removing the corrosion-resistant metal protective layer on the bonding pad, the circuit and the hole wall;

(12) coating the whole board and curing the solder resist material at one time;

(13) removing the solder resist material layer on the surface of the welding area by laser at an assembly site to manufacture a solder resist pattern, and cleaning and performing weldability treatment on the surface of the welding area;

(14) adding solder to the connecting disc, carrying out component mounting and insertion, and carrying out remelting welding or wave soldering.

And (1) coating a high polymer film on the double-sided copper-clad plate or the multilayer copper-clad plate which is already subjected to inner layer circuit manufacturing.

In the prior art, a photoinduced dry film is generally used as an electroplating-resistant mask, the photoinduced dry film is of a three-layer structure, a photosensitive adhesive coating is arranged between a carrier film and a protective film and consists of an adhesive, a photopolymerization monomer and the like, the pattern forming process is complex, and the steps of photoplotting, plate making, film pasting, exposure and development are required; moreover, the mask is expensive, has low strength and large thickness, generally more than 20 μm, limited resolution and poor masking effect.

The masking film does not need to have photosensitive performance, but the surface of the masking film needs to have a state of hydrophobic chemical plating active seeds and has the properties of electroplating resistance and etching resistance; comprises a dry PET, PI, RPP, BOPET, BOPP, PA, PPE, parylene and other polymer films made of single-component, multi-component, composite thermosetting, photocurable, thermocompressible, non-photosensitive and photosensitive materials, and monomeric, prepolymerized or polymerized liquid, paste or other materials; the coating method of the material comprises the processing of rolling, hot pressing, printing, plating, spraying, curtain coating and other methods or the combination of the methods; the thickness of the material is greater than the total metal thickness thickened on the line, and ranges from 2 μm to 3000 μm, preferably from 20 μm to 1000 μm.

In fact, the common pre-coated pressure-sensitive coating film and the heat-sensitive coating high polymer film can meet the requirements after being treated by the hydrophobic chemical plating active seeds. For example, a heat-sensitive PET or BOPET film with a thickness of 200 μm is hot-pressed as an electroplating-resistant mask.

And (2) drilling according to design requirements. The material to be drilled is a composite material formed by alternately laminating conductive copper foil and insulating material, and different from the traditional technology, the material drilled by the invention is additionally provided with a high polymer masking film attached to the surface of the board. The drilling tool may be either a mechanical drill or a focused laser beam.

If a mechanical drill bit is used for drilling holes, epoxy drilling dirt may appear on the hole wall, and before hole conductivity is carried out, the epoxy drilling dirt is removed by using a liquid medicine or a process which does not damage the high polymer film so as to ensure the hole metallization quality.

Wherein, in step (3), the hole is electrically conductive. The purpose of this step is to deposit an initial conductive layer on the hole walls to prime the next step of electroplating the hole walls.

The traditional chemical copper deposition process is that active noble metal particles are firstly deposited on the hole wall, and then copper hole metal is deposited to realize the surface conduction of the hole wall, so the hole conduction is the hole metallization process in the existing circuit board manufacturing technology; in the direct electroplating process, particularly in the carbon film method and the polymer film method, the substance for realizing the pore wall conductivity is not metal, so that the description of the process for forming the initial conductive layer by using the pore metallization is not accurate. In the present invention, the hole metallization is still used for description when referring to the prior art, and the hole conductivity is used for description when referring to the process of the present invention, and the hole conductivity includes both the hole conductivity process realized by metal and the hole conductivity process realized by non-metal materials.

There are two methods for achieving the object of this step, one is a direct electroplating method, for example, a carbon film method is used to blacken the hole, and an initial conductive layer is formed after the "pretreatment → black hole" step; the other is the traditional chemical copper deposition process, and the initial conducting layer is formed after the plating pretreatment → the activation treatment → the chemical copper plating. The thickness of the electroless copper plating is up to a lower limit, for example 1 μm, which ensures the reliability of the process.

In the step, because the plate surface is covered with the high polymer film, and the outer surface of the film surface has the property of thinning the chemical plating active seeds, the plate surface is masked, and after the step of directly electroplating the black holes of the method or after the activation treatment of the chemical copper deposition method, the plate surface does not have conductive substances such as carbon black, graphite and the like, and does not adhere to metal palladium active particles with catalytic action, chemically deposited copper and the like. Therefore, the plate surface and the copper-clad foil conducting layer can be maintained in an electric insulation state, and no metal copper is deposited on the plate surface in the subsequent electroplating process, so that the purpose of electroplating the copper conducting layer on the hole wall only is achieved.

And (4) electroplating copper, and depositing copper on the hole wall to thicken the hole wall.

In order to solve the problems that the total area is too small, the power lines are not uniform step by step, the current density is not easy to control and the like when the hole wall is electroplated, an electroplating balance block which is beneficial to improving the quality can be manufactured on a workpiece. The method comprises the following steps: after the step (1) is carried out, before or after the steps (2) and (3) are carried out, before the step (4) is carried out, laser is used for removing dead copper areas without electric functions, which are not wires and have an interval of more than 30 microns and preferably more than 50 microns with the intervals with the wires, or areas, the conducting layers of which need to be removed and do not have negative influence on the subsequent removing process, or areas, the functions of which are not influenced by the copper thickness, or areas, the functions of which are positively influenced by the copper thickness, of which are added with anti-electroplating film masking layers, so that copper foil surfaces below the masking layers are exposed, and dispersed patterns favorable for the balanced distribution of electroplating current when the hole walls are electroplated are formed.

The electroplated balance block is manufactured by only removing the organic material on the surface of the copper foil at the corresponding part. In this case, the optical power density of the focused laser spot used is greater than the minimum power density required to remove the organic material and is lower than or close to the minimum power density required to remove the underlying metal layer. Preferably greater than 1.2 times the minimum optical power density required to remove the organic material.

The control point of the step (4) is the plating time. At the moment, the whole area except the hole wall and the electroplating balance block on the plate surface is covered by a mask which is an insulating material and is not coated with copper in deposition on the surface although contacting with the electroplating liquid, so that only the hole wall and the balance block can deposit copper in the electroplating process, the electroplating time is enough, a copper deposition layer with enough thickness can be obtained on the hole wall, and the purpose of selectively controlling the copper thickness of the hole wall is achieved.

And (5) laser removing the high polymer film masking layer on the bonding pad and the circuit.

The processing aims to expose the copper surface of the bonding pad and the circuit, so that metal copper is electroplated on the bonding pad, the circuit and the hole wall for thickening, and metal such as nickel, gold or tin is electroplated on the copper surface for serving as an anti-etching protective layer.

The width of the area needing to be removed is different for different circuit boards and different circuits. If the width of the removal area does not correspond to the beam diameter or a multiple thereof, the removal speed is reduced, and overlapping is generated, and the overlapping area is processed twice by laser during overlapping, so that the processing effect of the non-overlapping area is inconsistent. The invention changes the diameter of the focused laser beam according to the shape and the size of the removed area, so that the diameter of the focused laser beam or the multiple thereof is exactly equal to the width of the area to be removed, thereby reducing or removing the overlapping of the laser processing area and improving the processing efficiency.

The step is the same as the process of manufacturing the electroplating balance block, and only organic materials on the surface of the copper foil at the corresponding part need to be removed. In this case, the optical power density of the focused laser spot is greater than the minimum power density required to remove the organic material and lower than or close to the minimum power density required to remove the underlying metal layer. Preferably greater than 1.2 times the minimum optical power density required to remove the organic material.

And (6) electroplating, and depositing copper on the bonding pad, the circuit and the hole wall to thicken. The purpose is to obtain a conductive layer of sufficient thickness to meet the electrical requirements of the circuit board design.

The control point in this step is the plating time. The plating time is enough, so that a copper deposition layer with enough thickness can be obtained on the hole wall, the bonding pad and the circuit, and the aim of selectively controlling the thickness of the conductive layer of the conductive pattern of the circuit board can be achieved.

In the existing circuit board manufacturing technology, a photo-induced dry film is generally adopted as an electroplating-resistant mask, the material is mostly ultraviolet-cured, and the thickness of a formed masking pattern is in a certain range and can not be too thin or too thick. Because the material is crosslinked and polymerized after hot-pressing film pasting and ultraviolet exposure to form a mask, the mask can be decomposed easily by a film removing chemical liquid medicine subsequently, and the mask caused by the subsequent technical requirement is only an imperfect sub-solid to some extent. The film is too thick, the resolution ratio is low, the required exposure amount is large, and the phenomenon of overexposure of a thin layer close to a light source and underexposure of a thin layer far away from the light source can occur; if too thin, the inherently weak sub-solid material may not achieve the mechanical strength necessary for masking, possibly resulting in bleeding.

The invention uses laser to directly remove and manufacture the plating-resistant masking pattern, uses non-photosensitive materials, and the materials are completely polymerized solids, have enough masking capability no matter the thickness is thin, and can not fall off or dissolve even if the electroplating time is longer. For circuit boards requiring thick copper traces, the plating time can be controlled until the metal layer thickness approaches or reaches 300 μm after selecting a thicker material in step (1), for example, selecting a mask with a thickness of 300 μm and removing the mask material on the surface of the desired trace with a laser.

And (7) electroplating, and depositing corrosion-resistant metal on the bonding pad, the circuit and the hole wall.

In the same step (6), the invention uses non-photosensitive plating-resistant materials, has good masking capability, can endure longer electroplating time, and can also endure harsher plating solution and operation conditions, therefore, more varieties of metals with corrosion resistance can be selected.

In step (8), the laser removes the non-circuit area high polymer film masking layer. The purpose is to expose the surface of the copper foil in the non-circuit area for etching removal in the next step.

In this step, the organic material layer on the surface of the copper foil at the corresponding portion needs to be removed, as in the step (5). In this case, the optical power density of the focused laser spot is greater than the minimum power density required to remove the organic material and lower than or close to the minimum power density required to remove the underlying metal layer. Preferably greater than 1.2 times the minimum optical power density required to remove the organic material.

Removing high molecular polymer on the surface of copper foil, wherein CO can be selected₂And (4) processing equipment with a laser as a light source. CO 2₂The laser emitted by the laser has a wavelength of about 10 μm and is in a far infrared band. Copper has a low absorption coefficient for laser light in this band, but the laser light in this band has good coupling with most high polymers. Therefore, the laser parameter range for removing the high polymer without damaging copper is wide. Selection of CO₂The laser can use large-diameter light spots, has high removal efficiency, low cost and high cost performance, and does not damage copper. In addition to CO₂Besides laser, the pulse fiber laser with the wavelength of about 1 μm has stable performance, convenient use and low cost, and is also suitable for removing high polymer materials and manufacturing corrosion-resistant patterns.

In step (9), the copper foil layer on the non-circuit area which is not covered by the corrosion-resistant metal protection layer is etched away.

Because the copper foil layer needing to be removed is masked by the high polymer film, no copper metal is deposited in the process of electroplating the circuit, the copper foil is still coated by the raw material, and compared with the prior art, the thickness is not increased, and the copper foil layer is easier to etch and remove. In the step, the traditional chemical etching technology is adopted, but the copper foil layer to be removed is thinner than the traditional technology, so that the required time is shorter, the side corrosion phenomenon is reduced, and the quality of the side wall of the manufactured conductive pattern is better.

And (10) carrying out electrical on-off inspection on the circuit board.

The most important function of the circuit board is to provide electrical connections. Whether each network meets the design requirements or not is judged through electrical on-off inspection, and the method is one of important links in modern circuit board production. In conventional circuit board technology, the on-off inspection is generally performed after forming a solder resist pattern and completing solderability coating of the lands and the insertion holes, such as after electroless nickel plating, gold plating, hot air leveling or immersion tin plating. The on-off inspection is carried out after the solder resist pattern and the solderability coating, and the method has the advantages that the surface of the pad of the test point is protected by the solderability metal, the inspection time period is suitable to be long, and the organization and management are convenient; a disadvantage is that if the circuit board has on-off problems, the problems mostly occur in the middle of the manufacturing process, because the problems are found late and it is costly to repair or scrap the circuit board. The electrical on-off inspection is carried out before the solder mask is manufactured, and the defects that the time period suitable for inspection is short and the window for organization management is small; the method has the advantages of timely finding out the problem of the manufacturing process and low cost for repairing or scrapping the problem board. In the invention, the electrical on-off inspection is arranged either before the step (12), (9) or after the step (11) or is arranged at the assembly site of the circuit board components.

And (11) removing the corrosion-resistant metal protective layer on the bonding pad, the circuit and the hole wall. If the electroplating quality and the plating variety meet the design requirements, the step can be skipped and the step (12) can be directly carried out. If the electrical on-off check is not performed after the step (9), whether the electrical on-off function in and between the groups of connection networks of the circuit board is correct can be checked after the step (11) and before the step (12).

Wherein, step (12), the whole board is coated and the solder resisting material is solidified once.

In the prior art, liquid photosensitive ink is generally adopted as a solder resist, the solder resist contains an adhesive and a photopolymerization monomer, the process of forming a pattern is very complicated, and a plurality of procedures such as coating, prebaking, exposing, developing, curing and the like are required besides a photo-drawing bottom plate; in addition, the price is high, the resolution ratio is not high, the phenomenon of welding pad leakage or welding pad overflow is frequently avoided between the detail distance connecting discs, and the coating quality is difficult to ensure.

The solder resist of the invention does not need to have light sensitivity, can meet the requirements of common precoating pressure-sensitive coating films and heat-sensitive coating films, has low price and high resolution, and can be used for manufacturing fine pattern structures. In addition, the invention adopts hot-pressing coating, does not need an additional curing process, leaves the solder resist pattern to be manufactured by laser on site before the component is assembled, and has simple flow. For example, the thermocompression bonding has a thickness of 5 μm to 300 μm, or further, 30 μm to 100 μm of a thermosensitive PI, PVC, PC, PET, PP, RPP, BOPET, BOPP, PA, PPE, parylene film as a solder resist.

For circuit boards with conductive patterns with a large thickness that exceed the covering capability of the high polymer film, liquid solder resist coating should be selected and applied under vacuum conditions as much as possible so that the solder resist covers the sidewalls of the conductive patterns in addition to the top surfaces of the conductive patterns. Because the invention uses laser to directly remove, manufacture the solder resist pattern and the liquid solder resist coating, does not need to have photosensitive property, and needs to be coated on the whole board and cured at one time.

And (13) removing the high polymer film layer on the surface of the welding area by using laser at an assembly site, manufacturing a solder resist pattern, and cleaning and performing weldability treatment on the surface of the welding area.

The key point of the step is that the solder mask pattern is manufactured on an assembly site, and once the solder mask pattern is manufactured, a fresh copper foil is exposed, and the processes of coating solder on the surface of the bonding pad, pasting the bonding pad, welding or inserting and welding are immediately carried out.

The laser processing in the step has the functions of selectively removing the solder resist material and manufacturing the solder resist pattern; but also has the function of cleaning the welding area and performing weldability treatment on the welding surface.

The technical key points of using laser to manufacture the solder resist pattern are as follows: the pattern size is accurate and smooth, and no burr is generated; the solder resist is removed cleanly, and the solder resist has no residue and no carbonization; the metal performance of the welding area is kept, the metal is not damaged, and remelting and color change are avoided; the adhesive force between the bonding pad and the base material is not affected, no overheating exists, the bonding pad is not raised, and the adhesive force is not reduced. The solder resist is generally a high molecular polymer, has large difference with metals physically and chemically, is easy to remove by laser processing, finds a window meeting the technical requirements, can be completed in one step by using laser with one wavelength in the same equipment, and can also be performed in two steps on different equipment.

Nanosecond ultraviolet laser, picosecond laser and femtosecond laser can be absorbed by high polymer to play a role in removing; can be well absorbed by copper metal, and plays a role in cleaning the surface of the copper metal. Particularly, picosecond and femtosecond laser has small single pulse energy, but the intensity of light, namely the laser power per unit area is large, only trace substances can be removed, but the surface performance of the material is changed, so that the method is a better choice for performing the weldability treatment on the surface of the bare copper. In the step, the laser processing system can be selected, and the solder mask pattern is manufactured by one step or multiple steps by using the same equipment, and the welding area is subjected to weldability processing.

CO₂The laser and the fiber laser have high absorption rate when being acted with high polymer and low absorption rate when being acted with copper. In general, such a laser cannot combine the functions of removing a high polymer solder resist pattern on a copper foil and cleaning and treating the solder area. Thus, another option for this step is to use two types of laser sources in two steps: selecting large light spot CO₂Removing the high polymer with high efficiency by laser to manufacture patterns; and removing the solder resist residues by nanosecond UV pulse laser or picosecond and femtosecond laser.

The first step is as follows: making a solder resist pattern, and generating a welding area: using longer wavelength CO₂And selectively photoetching a solder resist coating on the welding area by using a large-diameter laser spot emitted by a laser, removing the solder resist which possibly enters the hole, manufacturing a solder resist pattern, and generating the welding area.

And secondly, cleaning and performing solderability treatment on the surface of the welding area, removing residual solder resist on the surface of the welding area by using UV wave band with short wavelength or picosecond and femtosecond pulse laser with large light intensity, slightly photoetching the surface layer of the metal of the welding area, removing metal oxide, exposing the fresh surface of the metal, and generating solderability which is easily soaked by molten solder.

And (14) adding solder to the connecting disc, carrying out component mounting and inserting, and carrying out remelting welding and wave soldering.

In the method, because the weldable coating layer of the welding area is replaced by the fresh copper surface treated by laser, after the step (13) is finished, the step (14) is carried out in the shortest time possible to avoid the surface oxidation of the connecting disc, and under the condition of excellent weldability after laser treatment, the component assembly is finished, including component insertion, and the welding of the component is finished by directly applying the welding flux to the welding area treated by the laser; or directly printing solder paste on the laser-processed welding area in a missing mode, and then carrying out component mounting and reflow soldering; or component assembly according to other techniques.

In the present invention, laser processing is used for both drilling and removing the high polymer film on the copper foil layer. The laser processing equipment comprises one or more sets of data acquisition and processing systems, an equipment operating system, a laser light source, a light beam shaping and transmission system, a laser focusing system, a workpiece clamping and automatic and manual feeding and discharging system, a workpiece positioning and light beam movement and control system, a visual detection and laser power monitoring and compensation system, a cleaning and constant temperature system, a laser and equipment safe use system and the like; when the high polymer film is removed by laser or the copper foil on the non-circuit area is removed by laser, the energy and power on a unit area are constant according to the shape and the size of a processed area, the diameter of a light spot interacting with a material is taken as a variable, and one or a combination of high processing speed, no overlapping or certain overlapping when a processing path is overlapped, certain overlapping amount or spacing amount between pulses is taken as priority to generate laser parameters and processing data; during processing, the diameter of a light spot can be changed on line according to the preset laser parameters and the processing path requirements aiming at the structure of a processed pattern.

The invention has the advantages and effects that:

1. the invention can only electroplate and thicken the hole wall, is easy to control the thickness of the plating layer and can solve the problem that the thickness of the plating layer of the hole wall is thinner.

2. The invention uses the non-photosensitive material as the anti-electroplating material, reduces the cost, has good anti-electroplating performance, and can manufacture the conductive pattern with thicker hole walls and circuit metal copper layers.

3. The invention uses the laser direct removal method to manufacture the anti-plating pattern and the solder resist pattern, does not need pattern transfer, reduces steps and related materials and equipment, reduces cost and can manufacture fine conductive patterns and solder resist patterns.

4. According to the technical scheme, only holes and lines are electroplated, the thickness of the non-line part conductive layer is not increased, etching is easier, and finer conductive patterns can be manufactured.

5. In the laser pattern manufacturing process, the diameter of the focused laser beam is changed according to the shape and the size of the removed area, so that the diameter of the focused laser beam or the multiple of the diameter of the focused laser beam is exactly equal to the width of the area to be removed, the overlapping of laser processing areas can be reduced or removed, and the processing efficiency is improved.

6. The one-time curing solder resist material disclosed by the invention can be used for manufacturing a solder resist pattern on an assembly site, and a solderability coating step, material and equipment are not needed, so that the cost is greatly reduced, and the manufacturing difficulty is reduced.

7. The invention uses non-photosensitive material as solder resist, and uses lasers with different wavelengths, pulse widths and power densities to manufacture solder resist patterns and perform welding area cleaning and solderability treatment, thereby having higher efficiency and better treatment effect.

Drawings

FIG. 1a is a process flow diagram of the present invention (steps 1-7);

FIG. 1b is a process flow diagram of the present invention (steps 8-14);

in the figure: 1. an insulating substrate; 2. copper-clad plate copper layer; 3. a plating-resistant and etching-resistant high polymer film layer; 4. starting a conductive layer; 5. electroplating a copper layer; 6. depositing a copper layer; 7. a corrosion resistant metal protective layer; 8. a solder resist material layer; 9. solderability treating the surface; 10. welding flux; 11. and (3) a component.

Detailed Description

The invention will be further described with reference to the following examples. The following examples are illustrative and not intended to be limiting, and are not intended to limit the scope of the invention.

The common copper clad laminate in the electronic industry is used as a base material for manufacturing a circuit board, and comprises an insulating substrate 1 and a copper clad laminate 2.

Example 1

A method, material and equipment for manufacturing circuit board by selective electroplating of holes, laser-made plating-resistant patterns and pattern electroplating etching are disclosed, the method comprises:

(1) and coating a PET film of organic silicon resin on the double-sided hot-pressing surface of the Fr4 copper-clad plate without the pattern inside to form the electroplating-resistant and etching-resistant high polymer film layer 3.

A German and China DCT-BR300 type board brushing machine is used for performing double-sided board brushing (the board feeding speed is 1.2 mm/min; the swing frequency is 70 times/min) on the 1.5H/H copper-clad plate, compressed air is used for blowing off the moisture on the board surface, and the board is dried slightly or naturally.

Laminating/laminating is carried out, the front side and the back side of the copper-clad plate are respectively jointed with the PET film with the same size and the surface coated with the organic silicon resin and slightly rolled by a rubber roller, because the surface of the copper-clad plate is clean and free from dust after being brushed, the surface of the PET film with the surface coated with the organic silicon resin is also very clean, the PET film can be tightly jointed, the relative sliding can be ensured not to be generated in the subsequent operation process, the rolling of the rubber roller is carried out to discharge the air between the jointing surfaces, and the thickness of the PET film with the surface coated with the organic silicon resin is 10 mu m.

And (3) laminating the double-sided PET film-coated double-sided board by using DE-Zhong DCT-LA400 hot-pressing equipment (12 kilograms, 105-115 ℃, and the board moving speed is 200 mm/min).

(2) Drilling according to design requirements

Holes were drilled as per design requirements using midrange DCT-DM350 equipment. The designed data is imported into German Circuit CAM software, after the data is processed by the software, available punching data of equipment is generated, DM350 equipment is imported, the pressed board is placed on an equipment platform, CCD is positioned, full-automatic punching processing is carried out, specific drilling parameters are different according to different apertures, and the main parameter ranges are as follows: the rotating speed of the drill bit is 45000-100000 r/min, the feed speed is 15-30 mm/s, and the withdrawal speed is 25-40 mm/s.

(3) Activating and chemically depositing copper to form the initial conductive layer 4.

Removing oil with alkaline oil removing agent (50-60 deg.C, 5-8 min); pre-soaking with dilute hydrochloric acid solution (room temperature, 1-2 min); activating the palladium salt solution (25-30 ℃, 3-5 min); treating the dispergation solution (45-50 deg.C, 5-8 min); and (4) carrying out copper deposition on the alkaline copper deposition solution (40-45 ℃ and 60-80 min).

In the step, only the hole wall part can be contacted with the liquid medicine, and the rest part is completely covered by the PET film coated with the organic silicon resin on the surface. The organic silicon resin on the surface of the PET film has the characteristic of hydrophobic chemical activation, so that a chemical copper deposition layer cannot be formed on the final surface, and a thin chemical copper deposition layer is formed on the surface of the hole wall.

(4) And electroplating to form an electroplated copper layer 5 on the hole wall.

And (3) thickening electroplating of the hole wall copper layer by using Dezhong DCT-TP300 hole forming equipment. The uniformity of the hole wall plating layer is increased by adopting a small-current and long-time (0.1-0.15 ampere, 20-30 min) mode. In order to further improve the uniform plating and deep plating capability, the DCT-TP300 hole equipment is also provided with a liquid medicine jet flow circulation structure, a pulse direct current electroplating function and a reverse pulse electroplating function.

In this step, since the surface of the PET film coated with the silicone resin has no conductivity, the plating is performed only for the hole walls.

(5) Laser-removed PET film on bonding pad and circuit

Importing the data into German China Circuit CAM software, and generating a path for removing the PET film on the surface of the bonding pad and the surface of the circuit by laser after software processing and calculation; and (3) leading the path data into DreamRefeaTor equipment operation software of Dezhong DCT-U5 equipment, placing the board on an equipment platform, automatically aligning the CCD, and then automatically removing the PET film on the surface of the circuit and the surface of the bonding pad by laser.

In the step, when the circuitous CAM software calculates the laser processing path, the circuitous CAM software matches a proper spot diameter according to the size of a specific graph and generates a corresponding processing path; during the laser processing executed by the DreamRefeaTor software, the diameter of a light spot can be automatically changed in real time according to data, and the power can be adjusted, so that the laser removal can be completed with high efficiency and high quality. In the process, the related key laser processing parameters are as follows:

(6) electroplating copper on the bonding pad, the circuit and the hole wall for thickening to form a deposited copper layer 6.

Using DE-ZHONG DCT-TP300 hole forming equipment to thicken and electroplate copper layers of a bonding pad, a circuit and a hole wall, wherein the electroplating parameters are as follows: 025 ampere, 30 min.

(7) The pads, lines and hole walls are electroplated with tin and lead as a resist layer to form a resist metal protective layer 7.

Using a fluoborate plating solution with a tin-lead ratio of 6:4 and a current density of 2.5A/dm²Electroplating for 25min, subsequently cleaning the board surface, and air-drying by using compressed air.

(8) Laser-removed residual PET film on board (PET film on board except for bonding pad and circuit)

The operation steps are the same as the step (5), and the related key laser processing parameters are as follows:

(9) chemical etching to remove the copper layer in the non-circuit region

The German China DCT-EU400 automatic etching equipment integrates the functions of etching, cleaning and drying into a whole, and the board moving speed is 2.0 m/min.

(10) On-off inspection of manufactured board

And manually checking the on-off of the circuit on the manufactured board by using a universal meter.

(11) And removing the tin-lead protective layer on the bonding pad, the circuit and the hole wall.

Firstly, physically removing most of tin and lead by heating and hot air stripping; and then, immersing the board into a deplating solution, controlling the temperature and time according to the process requirements, and removing a small amount of residual tin-lead coatings on the bonding pad, the circuit and the hole wall by a chemical method.

(12) And printing the solder resist ink on the whole board and fully curing at one time to form a solder resist material layer 8.

Using a screen printing device to print solar PSR-400 series G23KHP type solder resist ink on two sides, and baking the ink in an oven at 120 ℃ for 60min for complete curing treatment.

(13) During assembly, the laser removes the solder mask to create a solder mask pattern, which cleans and solderably treats the solder area to solderably treat the surface 9.

The data of a solder resist removing path, a welding area copper surface cleaning and a weldability processing path are calculated by using CiucumCAM software, and the solder resist removing, the welding area copper surface cleaning and the weldability processing are carried out by using DCT-U5(20W) picosecond ultraviolet equipment, wherein the main parameters are as follows:

(14) solder 10 is added to the land, and component 11 is mounted and inserted, and reflow soldering and wave soldering are performed.

And adding solder to the surface of the bonding pad, carrying out surface mounting and insertion, and carrying out reflow soldering.

Example 2

A method, material and apparatus for manufacturing circuit boards by selective plating of holes, pads, laser resist patterns, chemical etching of conductive patterns, the method comprising:

(1) laminating PI film on board having 2 layers of patterns inside and copper foil laminated on surface but not having circuit

And (3) performing double-sided board brushing (the board feeding speed is 1.2mm/min and the swing frequency is 70 times/min) by using a German and China DCT-BR300 type board brushing machine, blowing off the moisture on the board surface by using compressed air, and drying by using slight heat or naturally.

Laminating the double-sided plate and PI film with DCT-MP300 laminator under buffer pressureThe distribution of heat on the plane of the plate surface is balanced, and a silicone rubber pad is used as a hot-pressing pad. According to the material characteristics, the hot pressing is carried out in five steps: step1 moderate temperature and low pressure (15 min; 80 ℃; 24N/cm)²) (ii) a step2 Medium temperature and Medium pressure (25 min; 140 ℃; 94N/cm)²) (ii) a step3 medium temperature and high pressure (25 min; 180 ℃; 188N/cm)²) (ii) a step4 high temperature and high pressure (60 min; 220 ℃; 188N/cm)²) (ii) a step5 was held at a constant pressure and cooled (45 min; 188N/cm)²)。

The initial board adopted in this example, i.e. the four-layer board with two conductive patterns inside and two copper foils laminated outside, for the purpose of clear subsequent description, the four conductive layers are referred to as top layer, secondary bottom layer and bottom layer in turn according to the cross-sectional structure, and the middle three dielectric layers are also referred to as medium layer, medium layer two and medium layer three in this way.

The dry film used in this example was a 25um dupont Kapton HN film.

(2) Laser drilling

And D, punching according to design requirements by using a De-Zhong DCT-D6 (femtosecond ultraviolet) laser device. And (3) importing the designed data into German Circuit CAM software, generating punching data available for equipment after the data is processed by the software, importing D6 equipment operation software DreamRefetor, placing the pressed board on an equipment platform, positioning a CCD (charge coupled device) and performing full-automatic punching.

Laser drilling key parameters:

wavelength of light

Pulse width

Spot diameter

Average power

Frequency of pulses

Speed of processing

Number of working operations

355nm

600fs

20um

12.5W

1200kHz

800mm/s

12 times (twice)

(3) Black hole

Removing oil with alkaline oil removing agent (45-50 deg.C, 10-15min, and oscillating); carrying out black hole (10-15min, adding swing) on suspension (black hole liquid) containing micro-nano carbon particles; removing trace black hole liquid attached to the board surface by using compressed air; natural air drying or low heat drying (25-40 deg.C) to evaporate the black pore liquid solvent and form a continuous carbon dielectric film on the inner wall surface of the pore, which is used as a conductive precursor in copper electroplating.

(4) Current balance area/plating accompanying area fabrication

According to the design requirement of the circuit, the PI film on the surface of the area conforming to the definition of the current balance area/the plating accompanying area on the board is removed, and the copper foil on the lower layer is exposed so as to balance the current when the hole wall is electroplated.

The method specifically comprises the steps of importing data into Germany China Circuit CAM software, and generating a path for removing a PI film on the surface of a current balance area/a plating accompanying area by laser after software processing and calculation; and guiding the path data into DreamReceaTor equipment operation software of Dezhong DCT-U5 equipment, placing the board on an equipment platform, and automatically aligning the CCD, and then automatically removing the PI film on the surface of the current balance area/the co-plating area by laser.

(5) Copper plating on hole wall

And (3) thickening electroplating of the hole wall copper layer by using Dezhong DCT-TP300 hole equipment (1.25 amperes, 20min-30min, which is the optimized electroplating parameter considering the influence of a current balance area/accompanying plating area).

(6) Laser removal of PI film on bonding pad and circuit

Importing the data into German China Circuit CAM software, and generating a path for removing a PI film on the surface of the pad and the surface of the circuit by laser after software processing and calculation; the path data is led into DreamReferTor equipment operation software of German DCT-U5(20W, nanosecond ultraviolet light source) equipment, a board is placed on an equipment platform, after CCD is automatically aligned, PI films on the surface of a bonding pad and the surface of a circuit are automatically removed by laser.

(7) Electroplating the bonding pad, the circuit and the hole wall to thicken the copper layer

And thickening and electroplating the copper layers of the bonding pad, the circuit and the hole wall by using German DCT-TP300 hole equipment for 20min at 2 amperes.

(8) Electroplating tin-lead

Using a fluoborate bath with a tin-lead ratio of 6:4 and a current density of 2.0A/dm²And electroplating tin-lead corrosion resistant layers on the bonding pads, the circuits and the hole walls within 45min, then performing board surface cleaning treatment, and performing air drying by using compressed air.

(9) Laser removal of PI film in non-line area

Importing the data into German China Circuit CAM software, and generating a path for removing the PI film on the non-line by laser through software processing and calculation; the path data is led into the operation software of the DreamReaTor equipment, the board is placed on an equipment platform, and after CCD is automatically aligned, laser is automatically processed, and in the process, the related key laser processing parameters are as follows:

wavelength of light

Pulse width

Spot diameter

Focal shift

Average power

Frequency of pulses

Speed of processing

Number of working operations

10600nm

--

250um

0mm

20

20kHz

1200mm/s

2 times (one time)

(10) Chemical etching to remove the copper layer in the non-circuit region

The German China DCT-EU400 automatic etching equipment integrates the functions of etching, cleaning and drying into a whole, and the board moving speed is 2.0 m/min.

(11) Performing electrical on-off inspection

And (4) carrying out electrical on-off inspection on the manufactured bare board according to a design schematic diagram.

(12) Removing tin-lead corrosion-resistant layer

The tin-lead corrosion resistant layers on the surfaces of the bonding pad, the circuit and the hole wall are removed by combining a physical method of hot oil soaking and a chemical method of tin-lead removing liquid soaking.

(13) Attaching an RPP film as a solder mask to the surface of the workpiece

Laminating the RPP film on the multi-layer copper-clad plate with the manufactured conductive pattern in a hot-pressing laminating modeAnd laminating parameters of a film laminating machine: pressure 20kg/cm²The temperature is 120 ℃ and the speed is 0.5 m/min.

(14) Removing the RPP thin film layer on the surface of the welding area by using laser to manufacture a solder resist pattern;

specifically, in this embodiment, a 20W ultraviolet nanosecond laser machine is used to manufacture the solder resist pattern, the circuit board is placed on a laser equipment adsorption table, engineering data of laser processing is imported, the circuit board and the processing data are accurately aligned, and the RPP film is laser-etched to form the solder resist pattern. And after the top surface is processed, the circuit board is turned over, and the bottom surface solder resist pattern is manufactured by the same method. The processing parameters are as follows:

power of	Frequency of	Pulse width	Speed of processing	Number of working operations
					5W	100kHz	20ns	600mm/s	2

(15) Adding solder to mount the component

And adding conductive paste to a welding area such as a welding pad, assembling components, and performing final curing through reflow soldering.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the inventive concept, and these changes and modifications are all within the scope of the present invention.