A method for manufacturing a circuit board by laser processing electroplating holes and anti-etching patterns

Abstract

The present invention relates to a method for manufacturing a circuit board by processing electroplated holes and anti-etching patterns with laser, drilling holes and depositing thin metal layers on the holes and board surfaces, attaching non-photosensitive masking films, laser removing the masking layers covering the hole walls to expose the hole walls, only electroplating and thickening the conductive layer in the holes, only electroplating metal anti-etching agents in the holes, then using laser to make anti-etching patterns, etching to make conductive patterns, applying non-photosensitive solder resists on non-circuit areas, using laser to make solder resist patterns at the assembly site, and cleaning and solderability treatment of the welding area surface; the present invention can optimize and shorten the manufacturing process of circuit boards as a whole, using non-photosensitive materials as anti-plating materials, only electroplating and thickening the conductive layer in the holes, only electroplating anti-etching and solderable metals on the hole walls, using laser to manufacture electroplated hole patterns, anti-etching patterns, and solder resist patterns in steps, with fewer steps, lower costs, and manufacturing more sophisticated circuit boards, and improving quality and efficiency. It is suitable for large-scale production of various circuit boards or circuit board samples and small-batch, multi-variety production.

Description

Technical Field

[0001] The invention relates to a method for making a circuit board by processing electroplating holes and anti-corrosion patterns with laser, using non-photosensitive materials as masking films and only electroplating and thickening the conductive layer in the holes, belonging to the technical field of circuit board manufacturing. Background Art

[0002] In today's world, electronic products are everywhere. Among them, one of the most important components is the circuit board, which is the electrical connection channel between various components and determines their respective electrical parameters and electrical logic relationships. At the same time, it is the installation and fixing carrier of various components and the skeleton of the product.

[0003] In terms of space, the electrical connections on the circuit board can be divided into two groups: the connections in the horizontal direction, which are usually called the conductive pattern, are located on the plane of each layer and are used to achieve the connection in the X and Y directions; the connections in the vertical direction are achieved by metallized holes, which pass through the insulating layer and the conductive layer in the Z direction to achieve the electrical interconnection between the conductive pattern layers. The traditional circuit board manufacturing technology mainly uses the subtractive method to manufacture the conductive pattern in the horizontal direction, that is, remove the excess copper foil on the copper-clad board, and use the remaining copper foil as the conductive pattern, as the part with electrical connection function including wires, pads, etc.; the electrical interconnection between layers in the vertical direction is mainly manufactured by the additive method, that is, add conductive material to the hole wall in the hole, and use the conductive hole wall to pass through the metal layer in the horizontal direction to achieve electrical interconnection.

[0004] As an important link in the electrical connection chain, the thickness of the conductive pattern in the X and Y directions and the conductive layer of the hole wall in the Z direction should be controlled separately on the circuit board so that the entire electrical channel meets the electrical requirements of the product. In particular, the thickness of the conductive layer on the hole wall should be independently controlled to prevent it from becoming a weak link in the connection chain. However, in general circuit board technology, the control of the copper thickness of the hole wall and the control of the copper thickness of the line interfere with each other, and a trade-off has to be made between the two, which is an important problem that affects the electrical performance and reliability of the circuit board.

[0005] Hole metallization generally adopts chemical methods, first using chemical plating or other means to deposit a thin conductive material layer on the insulating hole wall, and then electroplating the conductive metal to the required thickness on this initial conductive layer, so that the holes passing through the metal layer have reliable electrical interconnection indicators between layers. Based on different hole metallization technologies, different process routes have been derived, including masking method, graphic electroplating etching method, etc. The two process routes have their own advantages and disadvantages. Their technical solutions and key technologies are briefly described as follows:

[0006] Electroplating etching, commonly known as reverse plating, is a classic process for making printed circuit boards. The process after cutting starts with drilling and hole metallization. The initial conductive layer is formed on the hole wall by chemical plating or direct electroplating. After the metal copper is deposited on the hole wall and the board surface to a certain thickness by electroplating, the pattern is transferred. Through photosensitive film, exposure, and development, the copper foil of the non-circuit part is first masked with a thin layer of organic material, called anti-plating agent, and the circuit part, including the wire, pad, hole wall and other surfaces, is exposed. In this way, the surface of the metal copper that needs to be removed is masked, and it does not contact the liquid during the electroplating process, and no metal is deposited; the part that needs to be retained, including the wire, pad, and hole wall surface is exposed, and contacts the liquid during electroplating, or continues to electroplate copper, or directly electroplates etching-resistant metals, such as tin, tin-lead alloy, nickel and gold. Then, the organic material masking layer is removed to expose the copper foil of the non-circuit part, so that it reacts with the etchant during the etching process, dissolves into the solution after being oxidized and disappears from the board surface, while the surface of the circuit parts such as the wire, pad, and hole wall is shielded by the metal anti-corrosion agent and does not contact the etchant, so it is retained on the board to form the required conductive pattern. Finally, the solder mask pattern is made in the non-welding area of ​​the circuit board, and the solderable material is coated on the welding area.

[0007] The reverse plating process is a classic method for making circuit boards. It is mature and stable, but the process steps are many and the operation is complicated. The advantage is that the circuit part and the non-circuit part can be electroplated differently. Among them, after the hole metallization forms the initial conductive layer, the method of depositing copper on the hole wall by electroplating at one time until the required final thickness, and at the same time, increasing the thickness of the copper conductive layer on the rest of the board surface is called the full-board electroplating etching method; and after the hole metallization, a thin layer of copper is first electroplated on the hole wall and the board surface, and the copper thickness is controlled to just withstand the subsequent process. After the pattern is transferred, copper is electroplated to the required final thickness, that is, only the conductive pattern part is plated with thicker copper, and the non-conductive pattern part is plated with thinner copper. This method is called the pattern electroplating etching method.

[0008] The hole masking method is another commonly used process route for making circuit boards. The process after cutting starts with drilling and hole metallization. The initial conductive layer is formed on the hole wall by chemical plating or direct electroplating, and the metal copper is deposited on the hole wall and the board surface by electroplating to the final required thickness. Then, the pattern is transferred, and a thin layer of organic material, called an anti-etching agent, is used to mask the circuit part, including the wire, pad, and hole, by attaching a photosensitive film, exposing, and developing. The copper foil of the non-circuit part is exposed. In the subsequent etching process, the exposed non-circuit part of the copper foil surface contacts the etchant, an oxidation reaction occurs, and it dissolves into the solution and disappears from the board surface, while the surface of the circuit part such as the wire, pad, and hole wall is shielded by the anti-etching agent, does not contact the etchant, and is retained on the board to form the required conductive pattern. Like the reverse plating method, a solder mask pattern should also be made in the non-welding area of ​​the circuit board, and a solderable material should be coated on the welding area. The masking process is characterized by full-board electroplating of thickened copper, which is relatively simple. However, when making conductive patterns, it is more unfavorable to the production of fine circuit structures because it requires etching thicker copper foil.

[0009] In the above process route, the process of manufacturing Z-direction connection by hole metallization can be divided into two stages: the stage of manufacturing the initial conductive layer on the insulating hole wall and the stage of thickening the conductive layer on the hole wall by electroplating.

[0010] The technology for making the initial conductive layer can be divided into two methods: chemical copper plating and direct electroplating. Chemical copper plating uses a self-catalytic redox reaction to deposit copper (Cu) in the chemical copper plating solution on the hole wall. ++ ) ions are reduced to Cu, and these reduced copper nuclei themselves become catalysts for other copper ions in the solution, allowing the copper reduction reaction to continue on the surface of these new copper nuclei, and eventually forming a thin layer of copper on the insulating hole wall. Direct electroplating technology is a method of directly coating the hole wall with conductive carbon, palladium or polymer to form a continuous thin layer.

[0011] Whether in terms of technical implementation or electrical performance, the initial conductive layer is very thin, which is not enough to meet the requirements of electronic products for the conductivity and mechanical properties of the Z-direction link segment. It is also necessary to continue to add metal copper with better performance on the hole wall through electroplating. As mentioned earlier, depending on the range of copper thickening, there are two technical routes: full-board electroplating and pattern electroplating.

[0012] Comparing the X, Y plane and the Z-direction conductive layer, it can be seen that neither full-board electroplating nor graphic electroplating really solves the problem of the consistency between the thickness of the Z-direction conductive layer and the thickness of the X, Y-direction conductive layer of the circuit board connection link. In the process of electroplating and thickening the initial conductive layer, the thickness difference between the hole wall conductive layer constituting the Z-direction link and the board surface conductive layer constituting the X, Y link will also be enlarged. Because, on the X, Y plane, the conductive layer is based on the inherent conductive copper foil on the substrate, and the above-mentioned electroplating copper thickening hole wall conductive layer technology also increases the thickness of the conductive layer synchronously with the hole wall on the basis of the inherent copper foil on the board surface. Moreover, due to the factor of power line step-by-step, and also due to the depth capacity and uniform plating capacity of the electroplating process, the thickness of the board surface deposited layer will be greater than the hole wall deposited layer. However, the current and future electronic products have increasing requirements for the electrical connection performance of circuit boards, especially the requirements for improving the performance of Z-direction links. Therefore, it is necessary to develop a technology that can selectively electroplate thickened holes.

[0013] The inventor of application number CN201410190917.2 has disclosed a method for selectively electroplating conductive holes in a circuit board, which is suitable for the direct electroplating hole metallization process of a polymer conductive film method. The technical solution is to use a material that is resistant to electroplating, resistant to polymer conductive film deposition, and can be peeled off, that is, a polyester film that is peelable and coated with a silicone rubber adhesive, to mask all areas of the board surface, and expose the surface of the hole wall after drilling. Because these materials have the properties of resisting the pretreatment required for the deposition of polymer conductive films and resisting the deposition of polymer conductive films, in the subsequent direct electroplating process of polymer conductive films, polymer conductive films will only be added to the hole walls. During electroplating, the electroplating power supply uses the copper foil on the board surface as a conductive link channel to provide current to the hole walls, thereby realizing electroplating processing that only deposits copper on the hole walls. The problem is that the hole metallization process of direct electroplating of polymer conductive film method needs to be treated with a solution of 100g / L or more permanganate concentration at a temperature of 90 degrees Celsius for 70 seconds, which will produce destructive oxidation effects on both the peelable glue and the adhesive of the polyester film, causing the masking material, which has a weak adhesion to the substrate, to have a lower bonding strength with the copper foil, resulting in bone separation, delamination, seams, and openings, which will inevitably lead to poor masking board surface effects. After the hole wall is thickened by electroplating copper, the problem of uneven thickness of the copper foil on the copper foil board surface will be aggravated due to the infiltration, overflow, and immersion of the solution. In addition, the direct electroplating hole metallization process of polymer conductive film method has a limited scope of application and is not suitable for multi-layer circuit boards. Considering factors such as quality and cost, it is even more necessary to solve the problems of only metallization and electroplating hole wall faced by traditional chemical copper deposition hole metallization technology, black hole direct electroplating hole metallization technology, and palladium film method direct electroplating hole metallization technology. Because these technologies require acid, alkali or organic solvent treatment before hole metallization, it is obvious that the technical solution of using strippable colloidal materials is not strong enough and cannot be applied to mainstream hole metallization technology. It is necessary to find more suitable materials and methods.

[0014] The present invention uses laser direct material removal technology to manufacture circuit boards, and can only electroplate and thicken hole walls without a pattern transfer process, and directly manufacture anti-corrosion and solder resist patterns. Its manufacturing process is: depositing an initial conductive layer on a double-sided, multi-layer circuit board product that has been drilled, chemically plating or electroplating thin copper → pasting an anti-plating masking film → making a pattern of electroplating hole walls, laser removing the anti-plating masking film layer on the hole area, opening a window for liquid to enter the hole → electroplating, depositing copper on the hole wall to thicken the hole wall → electroplating and depositing a solderable anti-corrosion metal layer on the hole wall → laser removing the anti-plating masking film layer on the non-circuit area to make an anti-corrosion pattern → etching to make a conductive pattern → coating and curing solder resist material on the non-circuit area → removing organic materials on the conductor of the welding area with a laser at the assembly site to manufacture a solder resist pattern, and cleaning and solderability treatment of the surface of the welding area → adding solder to the connection pad, mounting and inserting components, and performing remelting welding and / or wave soldering.

[0015] The present invention can be used to replace various subtractive hole-making metal printed circuit board technologies. The starting raw material is a conductive metal foil material, including various rigid copper-clad boards, flexible copper-clad boards, or rigid-flex boards. The present invention uses laser processing technology and the same non-photosensitive material mask as the pattern of the electroplated hole wall and the solder mask pattern, respectively, to control the copper thickness of the hole wall, better meet the electrical requirements of electronic products for circuit boards, and is suitable for small-batch and multi-variety production of circuit boards, and is also suitable for batch manufacturing of circuit boards. Summary of the invention

[0016] In view of the deficiency of the prior art that only thickening holes can be electroplated, the present invention has developed a new manufacturing method, and the technical solution of the present invention is as follows:

[0017] A method for manufacturing a circuit board by processing electroplated holes and anti-etching patterns with laser, characterized in that: drilling holes and depositing a thin metal layer on the holes and the board surface, attaching a non-photosensitive masking film, laser removing the masking layer covering the hole wall to expose the hole wall, only electroplating to thicken the conductive layer in the hole, only electroplating metal anti-etching agent in the hole, then using laser to make an anti-etching pattern, etching to make a conductive pattern, applying a non-photosensitive solder resist on a non-circuit area, using laser to make a solder resist pattern at the assembly site, and cleaning and treating the surface of the welding area for solderability; the steps are:

[0018] (1) Depositing an initial conductive layer on a double-sided, multi-layer circuit board in production after drilling, and electroplating copper to a thickness that can withstand subsequent processes;

[0019] (2) Affixing a non-photosensitive organic film to the board surface as an anti-plating masking film;

[0020] (3) using a laser to remove the masking material covering the hole wall area to produce an anti-plating pattern, and using a laser to remove the anti-plating masking film layer on the surface of the clamping point of the electroplating fixture to expose the copper surface in the contact area with the electroplating fixture;

[0021] (4) Electroplating, depositing copper on the hole wall to thicken the conductive layer to the thickness required for final inspection;

[0022] (5) Electroplating, depositing corrosion-resistant and weldable metal on the hole wall;

[0023] (6) using a laser to remove the organic film material on the non-circuit area to expose the non-circuit copper and obtain an anti-etching masking pattern;

[0024] (7) chemical etching to remove copper from non-circuit areas to obtain a conductive pattern;

[0025] (8) Applying and curing non-photosensitive solder resist on non-circuit areas at one time;

[0026] (9) Use laser to remove organic materials on the conductors in the welding area at the assembly site, create solder resist patterns, and clean and treat the surface of the welding area for solderability;

[0027] (10) Add solder to the connection pad, mount and insert components, and perform reflow soldering and / or wave soldering.

[0028] The non-photosensitive organic film in step (2) is composed of several layers of different shapes and compositions, among which the layer in contact with the circuit board has viscosity and fluidity.

[0029] The non-photosensitive organic film in step (2) has anti-plating, anti-etching, and anti-soldering properties. The anti-plating masking film covering the circuit area does not need to be removed and serves as a solder resist film for the circuit area.

[0030] The step (2) includes depositing non-photosensitive organic film-forming substances on the plate surface and hole walls by electrophoresis, vacuum coating, vapor deposition and other technologies; including coating liquid photosensitive materials and dry photosensitive films by using existing technologies.

[0031] The coating method of step (8) includes spray printing and screen printing; the coating thickness is achieved so that it is flush with the masking film on the circuit after solidification or according to design requirements.

[0032] The steps (7) and (8) include using a laser to remove all remaining anti-plating masking films on the board surface after etching to obtain the pattern.

[0033] The step (8) also includes using laser to remove all remaining anti-plating masking films on the board surface, and then applying existing technology and materials to coat the entire board surface and cure it in one go with photosensitive and non-photosensitive solder resist.

[0034] The step (9) includes removing organic materials on the conductors in the soldering area by laser at the bare board manufacturing site to produce a solder resist pattern, and continuing the circuit board manufacturing process using existing technology and materials.

[0035] The specific instructions are as follows:

[0036] The present invention provides a method for manufacturing a circuit board by processing electroplating holes and anti-etching patterns with laser, comprising using a non-photosensitive material as a masking film and removing the masking film by laser photoetching to expose the hole; comprising only electroplating to thicken the conductive layer in the hole; comprising using a laser to manufacture an anti-etching pattern; comprising only coating a non-photosensitive solder resist on a non-circuit area; comprising using a laser to manufacture a solder resist pattern at the assembly site, and cleaning and treating the solderability of the surface of the welding area, which can achieve the goals of shortening the manufacturing process as a whole, improving quality and efficiency, reducing costs, and being environmentally friendly.

[0037] Step (1) depositing an initial conductive layer on a double-sided, multi-layer circuit board in process after drilling, and electroplating copper to a thickness that can withstand subsequent processes;

[0038] The purpose of making thin copper on the initial conductive layer is to increase the reliability of the process. The thickness can reach the lower limit of ensuring the reliability of the process. For example, after traditional chemical copper deposition or black hole formation by carbon film method, 1μm-5μm thin copper is electroplated.

[0039] Step (2) affixing a non-photosensitive organic film onto the board surface as an anti-plating masking film;

[0040] The prior art generally uses photosensitive dry film as an anti-plating mask. The photosensitive dry film is a three-layer structure. The photosensitive adhesive coating is between the carrier film and the protective film. It is composed of adhesives and photopolymer monomers. The pattern forming process is relatively complicated and requires the steps of photo-drawing, film pasting, exposure, and development. Moreover, it is expensive, has low strength, and is thick, generally above 20μm. The resolution is limited and the masking effect is poor. The masking film of the present invention does not need to have photosensitive properties. General pre-coated pressure-sensitive coating films and heat-sensitive coating films can meet the requirements. It is hot-pressed and coated, and the laser is directly removed to form a pattern. The process is simple. Moreover, it has high resolution, low price, high strength, good masking ability, can be removed in steps, and can withstand multiple electroplating processes. For example, a 20μm thick heat-sensitive PI, PVC, PC, PET, and PP film can be hot-pressed as an anti-plating mask, and parylene can also be used as an anti-plating mask.

[0041] The non-photosensitive organic film in step (2) is composed of several layers of different shapes and compositions, wherein the layer in contact with the circuit board has viscosity and fluidity; the non-photosensitive organic film has anti-plating / anti-etching properties, anti-soldering / anti-plating properties, and the anti-plating masking film covering the circuit area does not need to be removed and serves as a solder resist film in the circuit area. It includes depositing non-photosensitive organic film-forming materials on the board surface and hole wall by electrophoresis, vacuum coating, vapor deposition and other technologies; it includes coating liquid photosensitive materials and dry photosensitive films by using existing technologies.

[0042] Step (3) using a laser to remove the masking material covering the hole wall area to produce an anti-plating pattern, and using a laser to remove the anti-plating masking film layer on the surface of the clamping point of the electroplating fixture to expose the copper surface in the contact area with the electroplating fixture;

[0043] Laser removes the anti-plating masking film layer on the hole area to open a window for the liquid to enter the hole. For example, a pulsed IR laser with a wavelength of 1064nm is used, with the inner diameter of the hole as the outer contour, to remove the masking film covering the hole wall in blocks by ring cutting or photoetching point by point to expose the hole wall. In order to solve the problems of too small total area, uneven distribution of electric lines, and difficult control of current density when electroplating the hole wall, when making the hole wall electroplating pattern, a laser can be used to remove the dead copper area with no electrical function in the non-circuit part, or the area where its conductive layer needs to be removed and does not have a negative impact on the subsequent removal process, or the area where the copper thickness does not affect its function, or the area where increasing the copper thickness has a positive impact on the function. The anti-plating masking film increases the conductive area, disperses the electric lines, and forms a pattern that is conducive to the balanced electroplating process of the plated hole wall.

[0044] The pattern of the electroplated hole wall made by laser also includes removing dead copper areas with no electrical function that are not circuits and are spaced more than 30μm from the circuits, preferably more than 50μm apart, or areas where the conductive layer needs to be removed and does not have a negative impact on the subsequent removal process, or areas where the copper thickness does not affect its function, or areas where increasing the copper thickness has a positive effect on the function. The anti-plating mask film forms a balanced electroplating pattern that is beneficial to the plated hole wall.

[0045] Step (4) electroplating, depositing copper on the hole wall to thicken the conductive layer to the thickness required for final inspection;

[0046] The control point of this step is the electroplating time. At this time, except for the hole wall and the electroplating balance block, all areas on the board are covered with a mask. The mask is an insulating material. Although it is in contact with the electroplating solution, copper cannot be deposited on the surface. Therefore, only the hole wall and the balance block can deposit copper during the electroplating process. If the electroplating time is sufficient, a copper deposition layer of sufficient thickness can be obtained on the hole wall, achieving the purpose of selectively controlling the copper thickness of the hole wall.

[0047] Step (5) electroplating to deposit a corrosion-resistant and weldable metal on the hole wall;

[0048] The electroplated metal needs to have the corrosion resistance required in step (7). At the same time, it should also protect the corresponding area during transportation and storage of the circuit board and increase the solderability of the welding area during assembly of the circuit board.

[0049] The present invention uses non-photosensitive anti-plating materials with good masking ability, which can withstand longer electroplating time and more stringent plating solutions and operating conditions. In addition, because the other areas of the board surface are masked by a polymer film, the technology of the present invention can only deposit metal on the hole wall and the surface of the electroplating balance block, and the plating area is relatively small, saving materials. Therefore, more types of metals that are both corrosion-resistant, protective, and weldable can be selected, such as nickel and gold.

[0050] Step (6) using a laser to remove the organic film material on the non-circuit area to expose the non-circuit copper and obtain an anti-etching masking pattern;

[0051] When using a laser to remove the anti-electroplating masking film on a non-circuit area, when the ratio of the perimeter of the area to be removed to the diameter of the focused laser beam is small, preferably less than 10, the masking film on the surface of the substrate and the conductive metal copper underneath are removed by point-by-point and line-by-line photolithography using a focused laser beam; when the ratio of the perimeter of the area to be removed to the diameter of the focused laser beam is large, preferably greater than 15, the masking film on the surface of the substrate and the conductive metal copper underneath are first removed by point-by-point photolithography using a focused laser beam along the inner side of the envelope of the area to be removed and with the envelope as the boundary, until a closed insulating channel is formed around the unremoved portion of the area, and then a laser beam with a diameter lower than the minimum optical power density required to remove the metal copper but larger is used to heat the unremoved area, so that the anti-electroplating masking film on it and the conductive metal copper underneath are simultaneously separated from the substrate surface and removed.

[0052] When using laser to remove the anti-plating masking film on the non-circuit area, the focused laser light power density used is kept greater than the minimum power density required to remove the organic material, preferably greater than 1.2 times the minimum light power density required to remove the organic material and lower than or close to the minimum light power density required to remove the metal layer covered thereunder, and the focused laser beam diameter is changed according to the shape and size of the removed area to reduce or remove the overlap of the laser processing area and improve the processing efficiency. When laser removing the anti-plating masking film on the non-circuit area, lasers of the same wavelength and pulse width, as well as lasers of different wavelengths and pulse widths, can be used to complete the process under different parameters such as spot diameter, focal depth, and light power density.

[0053] Step (7) chemically etching to remove copper on non-circuit areas to obtain a conductive pattern;

[0054] Step (7) includes using a laser to remove all remaining anti-plating masking film on the board surface after etching to obtain the pattern.

[0055] In the present invention, the copper foil layer to be removed is masked by a polymer film during the chemical plating and electroplating hole wall process, and there is no copper metal deposition. It is still the raw material copper foil. Compared with the traditional technology, there is no increase in thickness and it is easier to etch and remove. Although this step uses the traditional chemical etching technology, because the copper foil layer to be removed is thinner than the traditional technology, it takes a shorter time, the side corrosion phenomenon is reduced, and the side wall quality of the produced conductive pattern is better.

[0056] After the conductive pattern is made, the circuit board in production can be checked for electrical continuity. The most important function of a circuit board is to provide electrical connection. It is one of the important links in modern circuit board production to judge whether each network meets the design requirements through electrical continuity inspection. In traditional circuit board technology, the continuity inspection is generally carried out after the solder mask pattern is formed and the solderability coating of the welding area and the plug-in hole is completed, such as after chemical nickel plating, gold plating, hot air leveling or tin immersion. The advantage of conducting the continuity inspection after the solder mask pattern and solderability coating is that the pad surface of the test point is protected by solderable metal, the time period suitable for inspection is long, and it is convenient for organization and management; the disadvantage is that if the circuit board has a continuity problem, the problem mostly occurs in the middle of the manufacturing process, because the problem is discovered late, and the cost of repairing the problem or scrapping the circuit board is high. In the present invention, the electrical continuity inspection should be arranged after step (7) and before (8). The disadvantage of conducting the electrical continuity inspection before manufacturing the solder mask is that the time period suitable for inspection is short and the window for organizational management is small; the advantage is that process problems can be discovered in time, and the cost of repairing or scrapping the problem board is low.

[0057] Step (8) coating the non-circuit area with a non-photosensitive solder resist and curing it once;

[0058] The prior art generally uses liquid photosensitive ink as solder resist, which contains adhesives and photopolymerizable monomers. The pattern forming process is very complicated and requires multiple processes such as coating, pre-baking, exposure, development, and curing. Moreover, it is expensive, has low resolution, and is difficult to ensure the coating quality between fine pitch connection pads. The solder resist of the present invention does not need to have photosensitive properties. General pre-coated pressure-sensitive coating films and heat-sensitive coating films can meet the requirements. It is cheap and has high resolution, and can produce fine pattern structures. In addition, the present invention uses hot pressing coating, which does not require an additional curing process. The solder resist pattern is left to be produced on-site by laser before component assembly, and the process is simple. For example, a heat-pressed paste with a thickness of 20μm-200μm of thermal-sensitive PI, PVC, PC, PET, and PP films is used as a solder resist, and parylene can also be used as a solder resist.

[0059] The coating method of step (8) includes spray printing and leak printing; the coating thickness is achieved after curing and is flush with the masking film on the circuit or according to the design requirements. It also includes using laser to remove all remaining anti-plating masking films on the board surface, and then applying existing technology and materials to the entire board surface and curing the photosensitive and non-photosensitive solder resist at one time.

[0060] Step (9) using a laser to remove organic materials on the conductors in the welding area at the assembly site, to produce a solder resist pattern, and to clean and treat the surface of the welding area for solderability;

[0061] This step can be completed in one step on the same equipment, or it can be carried out in two steps on different equipment, namely, the first step: making a solder resist pattern and generating a welding area: using a laser to selectively photoetch to remove the solder resist coating on the welding area, making a solder resist pattern and generating a welding area; the second step, cleaning and solderability treatment of the welding area surface, using another laser to remove the solder resist residue on the surface of the welding area, and slightly photoetching the metal surface layer of the welding area to remove metal oxides, exposing a fresh metal surface, and creating solderability that is easily wetted by molten solder.

[0062] The step (9) includes removing organic materials on the conductors in the soldering area by laser at the bare board manufacturing site to produce a solder resist pattern, and continuing the circuit board manufacturing process using existing technology and materials.

[0063] Step (10) adds solder to the connection pad, mounts and inserts components, and performs reflow soldering and / or wave soldering.

[0064] The present invention can optimize and shorten the circuit board manufacturing process as a whole, improve quality and efficiency, reduce costs, and be environmentally friendly. Non-photosensitive materials are used as anti-plating materials, only the conductive layer in the hole is plated to thicken, and only the corrosion-resistant and weldable metals are plated on the hole wall. The laser is used to manufacture the electroplated hole pattern, the anti-etching pattern, and the solder mask pattern step by step. There are fewer steps and lower costs, and more sophisticated circuit boards can be manufactured. The present invention is suitable for mass production of various circuit boards, and is also suitable for circuit board samples and small batch and multi-variety production.

[0065] The advantages and effects of the present invention are:

[0066] 1. The present invention only electroplates to thicken the hole wall, which makes it easy to control the thickness of the coating and can solve the problem of thin thickness of the hole wall coating.

[0067] 2. The present invention uses non-photosensitive materials as anti-corrosion materials and solder resist materials, and has low cost.

[0068] 3. The present invention uses a laser direct removal method to manufacture anti-corrosion patterns and solder resist patterns without graphic transfer, thereby reducing steps and related materials and equipment, lowering costs, and being able to manufacture fine conductive patterns and solder resist patterns.

[0069] 4. The present invention uses a film pre-coated with a heat-sensitive or pressure-sensitive solder resist material as a solder resist, and uses lasers with different wavelengths, pulse widths, and power densities to manufacture solder resist patterns, which is more efficient and has a better processing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 : Process flow chart of embodiment 1;

[0071] Figure 2 : Process flow chart of embodiment 2;

[0072] Among them: 1. Insulating substrate 2. Copper layer of copper clad laminate 3. Initial conductive layer 4. Electroplated thin copper 5. Anti-plating masking film 6. Hole electroplating layer 7. Corrosion-resistant and solderable metal 8. Solder resist material layer 9. Cleaned and solderable surface 10. Solder 11. Components

[0073] In the attached drawings, each letter A\B\C\D\E\F\G\H corresponds to a partial enlarged schematic diagram of each step. DETAILED DESCRIPTION

[0074] The present invention will be further described below in conjunction with the following embodiments. The following embodiments are illustrative, not restrictive, and the protection scope of the present invention cannot be limited by the following embodiments.

[0075] Example 1

[0076] In the electronics industry, copper clad laminate is often used as a basic material to make circuit boards. The copper clad laminate includes an insulating substrate 1 and a copper layer 2 of the copper clad laminate.

[0077] This embodiment takes a double-sided printed circuit board as an example, and the specific processing steps are as follows:

[0078] (1) The copper-clad laminate, a substrate of the circuit board, comprises an insulating substrate 1 and a copper layer 2 of the copper-clad laminate. The copper-clad laminate is drilled, and an initial conductive layer 3 is deposited on the semi-finished product of the double-sided circuit board after the drilling. The copper is electroplated to a thickness that can withstand subsequent processes, thereby forming an electroplated thin copper 4.

[0079] The purpose of making a thin copper layer on the initial conductive layer is to increase the reliability of the process, and the thickness of the thin copper layer only needs to reach the lower limit of ensuring the reliability of the process.

[0080] The double-sided board with holes drilled is electroplated. Specifically, the double-sided board with holes drilled is brushed to remove the burrs at the hole mouth and clean the board surface. Then the holes are normally blackened and copper is electroplated. The electroplating parameters are: 10ASF*30min, and the thickness of the coating in the hole is about 5um.

[0081] (2) A non-photosensitive polymer film is attached to the board surface as an anti-plating masking film 5.

[0082] The prior art generally uses photosensitive dry film as an anti-plating mask. The photosensitive dry film is a three-layer structure. The photosensitive adhesive coating is between the carrier film and the protective film. It is composed of adhesives and photopolymer monomers. The pattern forming process is relatively complicated and requires the steps of photo-drawing, film pasting, exposure, and development. Moreover, it is expensive, has low strength, and is thick, generally above 20μm. The resolution is limited and the masking effect is poor. The masking film of the present invention does not need to have photosensitive properties. General pre-coated pressure-sensitive coating films and heat-sensitive coating films can meet the requirements. It is hot-pressed and coated, and the laser is directly removed to form a pattern. The process is simple. Moreover, it has high resolution, low price, high strength, good masking ability, can be removed in steps, and can withstand multiple electroplating processes. For example, a 20μm thick heat-sensitive PI, PVC, PC, PET, and PP film can be hot-pressed as an anti-plating mask, and parylene can also be used as an anti-plating mask.

[0083] The double-sided copper-plated board is brushed to roughen and clean the surface of the double-sided board to enhance the bonding strength between the copper surface and the polymer film to be bonded. Then the high polymer film RPET with anti-electroplating performance is hot-pressed on the double-sided copper-clad board by a film laminating machine. The film thickness is about 10um, and the laminating parameters are: pressure 15kg / cm 2 , temperature 95℃, speed 100mm / min.

[0084] (3) Use laser to remove the masking material covering the hole wall area to produce an anti-plating pattern, and use laser to remove the anti-plating masking film layer on the surface of the clamping point of the electroplating fixture to expose the copper surface in the contact area with the electroplating fixture.

[0085] Laser removes the anti-plating masking film layer on the hole area to open a window for the liquid to enter the hole. For example, a pulsed IR laser with a wavelength of 1064nm is used, with the inner diameter of the hole as the outer contour, to remove the masking film covering the hole wall in blocks by ring cutting or photoetching point by point to expose the hole wall. In order to solve the problems of too small total area, uneven distribution of electric lines, and difficult control of current density when electroplating the hole wall, when making the hole wall electroplating pattern, a laser can be used to remove the dead copper area with no electrical function in the non-circuit part, or the area where its conductive layer needs to be removed and does not have a negative impact on the subsequent removal process, or the area where the copper thickness does not affect its function, or the area where increasing the copper thickness has a positive impact on the function. The anti-plating masking film increases the conductive area, disperses the electric lines, and forms a pattern that is conducive to the balanced electroplating process of the plated hole wall.

[0086] The pattern of the electroplated hole wall made by laser also includes removing dead copper areas with no electrical function that are not circuits and are spaced more than 30μm from the circuits, preferably more than 50μm apart, or areas where the conductive layer needs to be removed and does not have a negative impact on the subsequent removal process, or areas where the copper thickness does not affect its function, or areas where increasing the copper thickness has a positive effect on the function. The anti-plating mask film forms a balanced electroplating pattern that is beneficial to the plated hole wall.

[0087] Specifically, this embodiment uses a 20W ultraviolet nanosecond laser machine to remove the RPET film on the hole wall area, the clamping point of the electroplating fixture, and the electroplating balance block. The circuit board is placed on the laser equipment adsorption table, the engineering data of the laser processing is imported, the circuit board is accurately aligned with the processing data, and the RPET film is removed by laser photoetching. After the top surface processing is completed, the circuit board is turned over, and the film on the bottom surface of the copper clad board is removed in the same way. The processing parameters are as follows:

[0088] Power / W Frequency / kHz Pulse width / ns Processing speed / mm / s Processing times 5.5 150 20 800 1

[0089] (4) Electroplating: depositing copper on the hole wall to thicken the conductive layer to the thickness required for final inspection, forming the hole electroplating layer 6.

[0090] The control point of this step is the electroplating time. At this time, except for the hole wall and the electroplating balance block, all areas on the board are covered with a mask. The mask is an insulating material. Although it is in contact with the electroplating solution, copper cannot be deposited on the surface. Therefore, only the hole wall and the balance block can deposit copper during the electroplating process. If the electroplating time is sufficient, a copper deposition layer of sufficient thickness can be obtained on the hole wall, achieving the purpose of selectively controlling the copper thickness of the hole wall.

[0091] Since the electroplating area is small, a small current density is used for electroplating in this step. The electroplating parameters are: 10ASF*120min, and the thickness of the coating in the hole is about 25um.

[0092] (5) Electroplating: electroplating a corrosion-resistant and solderable metal on the hole wall to form a corrosion-resistant and solderable metal 7.

[0093] The electroplated metal needs to have the corrosion resistance required in step (7). At the same time, it should also protect the corresponding area during transportation and storage of the circuit board and increase the solderability of the welding area during assembly of the circuit board.

[0094] The present invention uses non-photosensitive anti-plating materials with good masking ability, which can withstand longer electroplating time and more stringent plating solutions and operating conditions. In addition, because the other areas of the board surface are masked by a polymer film, the technology of the present invention can only deposit metal on the hole wall and the surface of the electroplating balance block, and the plating area is relatively small, saving materials. Therefore, more types of metals that are both corrosion-resistant, protective, and weldable can be selected, such as nickel and gold.

[0095] According to the requirements of electroplating area and coating thickness, soft gold is electroplated on the hole wall and pad as a solderable metal protective layer. Electroplating soft gold parameters: 0.3ASD*10min, the coating thickness in the hole is about 2um.

[0096] (6) Use laser to remove the organic film material on the non-circuit area to expose the non-circuit copper and obtain an anti-etching mask pattern.

[0097] When using a laser to remove the anti-electroplating masking film on a non-circuit area, when the ratio of the perimeter of the area to be removed to the diameter of the focused laser beam is small, preferably less than 10, the masking film on the surface of the substrate and the conductive metal copper underneath are removed by point-by-point and line-by-line photolithography using a focused laser beam; when the ratio of the perimeter of the area to be removed to the diameter of the focused laser beam is large, preferably greater than 15, the masking film on the surface of the substrate and the conductive metal copper underneath are first removed by point-by-point photolithography using a focused laser beam along the inner side of the envelope of the area to be removed and with the envelope as the boundary, until a closed insulating channel is formed around the unremoved portion of the area, and then a laser beam with a diameter lower than the minimum optical power density required to remove the metal copper but larger is used to heat the unremoved area, so that the anti-electroplating masking film on it and the conductive metal copper underneath are simultaneously separated from the substrate surface and removed.

[0098] When using laser to remove the anti-plating masking film on the non-circuit area, the focused laser light power density used is kept greater than the minimum power density required to remove the organic material, preferably greater than 1.2 times the minimum light power density required to remove the organic material and lower than or close to the minimum light power density required to remove the metal layer covered thereunder, and the focused laser beam diameter is changed according to the shape and size of the removed area to reduce or remove the overlap of the laser processing area and improve the processing efficiency. When laser removing the anti-plating masking film on the non-circuit area, lasers of the same wavelength and pulse width, as well as lasers of different wavelengths and pulse widths, can be used to complete the process under different parameters such as spot diameter, focal depth, and light power density.

[0099] Use laser to remove the RPET anti-plating masking film on the non-circuit area. Specifically, this embodiment uses a 20W ultraviolet nanosecond laser machine to remove the RPET film on the non-circuit area. Place the circuit board on the laser equipment adsorption table, import the engineering data of laser processing, accurately align the circuit board with the processing data, and remove the RPET film by laser photoetching. After the top surface processing is completed, turn the circuit board over and remove the film on the bottom surface of the copper clad board in the same way. The processing parameters are as follows:

[0100] Power / W Frequency / kHz Pulse width / ns Processing speed / mm / s Processing times 5.5 150 20 800 1

[0101] (7) Chemical etching removes the copper on the non-circuit area to obtain a conductive pattern.

[0102] In the present invention, the copper foil layer to be removed is masked by a polymer film during the chemical plating and electroplating hole wall process, and there is no copper metal deposition. It is still the raw material copper foil. Compared with the traditional technology, there is no increase in thickness and it is easier to etch and remove. Although this step uses the traditional chemical etching technology, because the copper foil layer to be removed is thinner than the traditional technology, it takes a shorter time, the side corrosion phenomenon is reduced, and the side wall quality of the produced conductive pattern is better.

[0103] After the conductive pattern is made, the circuit board in production can be checked for electrical continuity. The most important function of a circuit board is to provide electrical connection. It is one of the important links in modern circuit board production to judge whether each network meets the design requirements through electrical continuity inspection. In traditional circuit board technology, the continuity inspection is generally carried out after the solder mask pattern is formed and the solderability coating of the welding area and the plug-in hole is completed, such as after chemical nickel plating, gold plating, hot air leveling or tin immersion. The advantage of conducting the continuity inspection after the solder mask pattern and solderability coating is that the pad surface of the test point is protected by solderable metal, the time period suitable for inspection is long, and it is convenient for organization and management; the disadvantage is that if the circuit board has a continuity problem, the problem mostly occurs in the middle of the manufacturing process, because the problem is discovered late, and the cost of repairing the problem or scrapping the circuit board is high. In the present invention, the electrical continuity inspection should be arranged after step (7) and before (8). The disadvantage of conducting the electrical continuity inspection before manufacturing the solder mask is that the time period suitable for inspection is short and the window for organizational management is small; the advantage is that process problems can be discovered in time, and the cost of repairing or scrapping the problem board is low.

[0104] The present invention uses a traditional chemical etching process to etch away the copper layer in the non-circuit area. Since the conductive layer in the non-circuit area is covered by an anti-electroplating masking film, the copper thickness of the area does not increase during electroplating, thereby greatly reducing the etching difficulty and obtaining a more sophisticated circuit.

[0105] (8) coating and curing a non-photosensitive solder resist on the non-circuit area at one time to form a solder resist material layer 8;

[0106] The prior art generally uses liquid photosensitive ink as solder resist, which contains adhesives and photopolymerizable monomers. The pattern forming process is very complicated and requires multiple processes such as coating, pre-baking, exposure, development, and curing. Moreover, it is expensive, has low resolution, and is difficult to ensure the coating quality between fine pitch connection pads. The solder resist of the present invention does not need to have photosensitive properties. General pre-coated pressure-sensitive coating films and heat-sensitive coating films can meet the requirements. It is cheap and has high resolution, and can produce fine pattern structures. In addition, the present invention uses hot pressing coating, which does not require an additional curing process. The solder resist pattern is left to be produced on-site by laser before component assembly, and the process is simple. For example, a heat-pressed paste with a thickness of 20μm-200μm of thermal-sensitive PI, PVC, PC, PET, and PP films is used as a solder resist, and parylene can also be used as a solder resist.

[0107] In this embodiment, the electrostatic spraying process is used to spray the KSM-386 thermosetting ink produced by Suzhou Guangxin Photosensitive New Materials Co., Ltd. on the non-circuit area of ​​the double-sided board, and fully cure it at one time. The curing conditions are: 150°C*30min, and the solder mask ink thickness is about 20um.

[0108] (9) using laser to remove organic materials on the conductor of the welding area at the assembly site to produce a solder resist pattern, and cleaning and solderability treatment of the welding area surface to form a cleaned and solderability treated surface 9;

[0109] This step can be completed in one step on the same equipment, or it can be carried out in two steps on different equipment, namely, the first step: making a solder resist pattern and generating a welding area: using a laser to selectively photoetch to remove the solder resist coating on the welding area, making a solder resist pattern and generating a welding area; the second step, cleaning and solderability treatment of the welding area surface, using another laser to remove the solder resist residue on the surface of the welding area, and slightly photoetching the metal surface layer of the welding area to remove metal oxides, exposing a fresh metal surface, and creating solderability that is easily wetted by molten solder.

[0110] Specifically, the RPET film on the conductor in the welding area is first removed by laser, and the removal parameters are the same as step (6). Then, a UV picosecond laser with a smaller single pulse energy is used to clean and treat the welding area for weldability. The processing parameters are as follows:

[0111] Power / W Frequency / kHz Pulse width / ps Processing speed / mm / s Processing times 10 1000 12 2000 1

[0112] (10) Solder 10 is added to the connection pad, and components 11 are mounted and inserted, followed by reflow soldering and selective wave soldering.

[0113] Example 2

[0114] In the electronics industry, copper clad laminate is often used as a basic material to make circuit boards. The copper clad laminate includes an insulating substrate 1 and a copper layer 2 of the copper clad laminate.

[0115] This embodiment takes a four-layer circuit board with inner layer circuits fabricated as an example, and the specific processing steps are as follows:

[0116] (1) The copper-clad laminate substrate of the circuit board includes an insulating substrate 1 and a copper layer 2 of the copper-clad laminate. The copper-clad laminate is drilled, and an initial conductive layer 3 is deposited on the semi-finished product of the four-layer circuit board after the drilling. Copper is electroplated to a thickness that can withstand subsequent processes to form an electroplated thin copper 4.

[0117] Chemical copper is deposited on the four-layer circuit board with holes drilled and inner circuits completed, and copper electroplating is performed. Specifically, the circuit board with holes drilled is brushed to remove burrs at the hole mouth and the board surface is cleaned. Then, copper electroplating is performed after removing the glue residue. The electroplating parameters are: 10ASF*35min, and the thickness of the coating in the hole is about 5um.

[0118] (2) A non-photosensitive polymer film RPP is attached to the board surface as an anti-plating masking film 5.

[0119] The four-layer circuit board after thin copper electroplating is brushed and dried, and then hot-pressed to bond the anti-electroplating polymer film RPP. Bonding parameters: pressure 15kg / cm 2 , film thickness is about 10um, temperature is 95℃, speed is 100mm / min.

[0120] (3) Use laser to remove the masking material covering the hole wall area to produce an anti-plating pattern, and use laser to remove the anti-plating masking film layer on the surface of the clamping point of the electroplating fixture to expose the copper surface in the contact area with the electroplating fixture.

[0121] Specifically, this embodiment uses a 20W ultraviolet nanosecond laser machine to remove the RPP film on the hole wall area, the clamping point of the electroplating fixture, and the electroplating balance block. The circuit board is placed on the laser equipment adsorption table, the engineering data of the laser processing is imported, the circuit board is accurately aligned with the processing data, and the RPP film is removed by laser photoetching. After the top surface processing is completed, the circuit board is turned over and the bottom surface film is removed in the same way. The processing parameters are as follows:

[0122] Power / W Frequency / kHz Pulse width / ns Processing speed / mm / s Processing times 6.5 200 20 600 1

[0123] (4) Electroplating: depositing copper on the hole wall to thicken the conductive layer to the thickness required for final inspection, forming the hole electroplating layer 6.

[0124] The control point of this step is the electroplating time. At this time, except for the hole wall and the electroplating balance block, all areas on the board are covered with a mask. The mask is an insulating material. Although it is in contact with the electroplating solution, copper cannot be deposited on the surface. Therefore, only the hole wall and the balance block can deposit copper during the electroplating process. If the electroplating time is sufficient, a copper deposition layer of sufficient thickness can be obtained on the hole wall, achieving the purpose of selectively controlling the copper thickness of the hole wall.

[0125] Since the electroplating area is small, a small current density is used for electroplating in this step. The electroplating parameters are: 10ASF*120min, and the thickness of the coating in the hole is about 25um.

[0126] (5) Electroplating: electroplating a corrosion-resistant and solderable metal on the hole wall to form a corrosion-resistant and solderable metal 7.

[0127] The electroplated metal needs to have the corrosion resistance required in step (7). At the same time, it should also protect the corresponding area during transportation and storage of the circuit board and increase the solderability of the welding area during assembly of the circuit board.

[0128] The present invention uses non-photosensitive anti-plating materials with good masking ability, which can withstand longer electroplating time and more stringent plating solutions and operating conditions. In addition, because the other areas of the board surface are masked by a polymer film, the technology of the present invention can only deposit metal on the hole wall and the surface of the electroplating balance block, and the plating area is relatively small, saving materials. Therefore, more types of metals that are both corrosion-resistant, protective, and weldable can be selected, such as nickel and gold.

[0129] According to the requirements of electroplating area and coating thickness, soft gold is electroplated on the hole wall and pad as a solderable metal protective layer. Electroplating soft gold parameters: 0.3ASD*15min, the coating thickness in the hole is about 2um.

[0130] (6) Using laser to remove the RPP film material on the non-circuit area to expose the non-circuit copper and obtain an anti-etching masking pattern;

[0131] Use laser to remove the RPP anti-plating masking film on the non-circuit area of ​​the four-layer circuit board. The removal method and parameters are the same as step (3).

[0132] (7) Chemical etching removes the copper on the non-circuit area to obtain a conductive pattern.

[0133] The copper layer in the non-circuit area is etched away using a traditional chemical etching process. Because the conductive layer in the non-circuit area is covered by an anti-plating masking film, the copper thickness in this area does not increase during electroplating, thus greatly reducing the difficulty of etching and allowing for more sophisticated circuits.

[0134] (8) coating the entire board with a non-photosensitive solder resist and curing it once to form a solder resist material layer 8;

[0135] In this embodiment, a PI film is laminated on the entire four-layer circuit board as a solder resist. Specifically, before laminating the PI film, a laser is used to remove all remaining anti-plating masking films on the board surface. The removal method and parameters are the same as step (3). Then a laminator is used to laminate the completed circuit board and PI film. The PI film is Kapton HN film produced by DuPont with a thickness of 25um. Silicone rubber pads are used as hot pressing pads during lamination. Before lamination, the RPP masking film needs to be completely removed by laser. According to the material properties, the hot pressing stages and parameters are as follows:

[0136] Serial number Pressing pressure (N / cm2) Pressing temperature(℃) Pressing time (minutes) Phase 1 24 80 15 Phase 2 94 140 25 Phase 3 188 180 25 Phase 4 188 220 60 Phase 5 188→0 220 → Room temperature 45

[0137] (9) At the assembly site, a laser is used to remove organic materials on the conductors in the welding area to produce a solder resist pattern, and the surface of the welding area is cleaned and treated for solderability to form a cleaned and solderable surface 9;

[0138] This step can be completed in one step on the same equipment, or it can be carried out in two steps on different equipment, namely, the first step: making a solder resist pattern and generating a welding area: using a laser to selectively photoetch to remove the solder resist coating on the welding area, making a solder resist pattern and generating a welding area; the second step, cleaning and solderability treatment of the welding area surface, using another laser to remove the solder resist residue on the surface of the welding area, and slightly photoetching the metal surface layer of the welding area to remove metal oxides, exposing a fresh metal surface, and creating solderability that is easily wetted by molten solder.

[0139] Specifically, this embodiment uses a 20W ultraviolet nanosecond laser machine to make the solder mask pattern. The circuit board is placed on the laser equipment adsorption table, the engineering data of the laser processing is imported, the circuit board is accurately aligned with the processing data, and the laser photoetching PI forms the solder mask pattern. After the top surface processing is completed, the circuit board is turned over, and the bottom surface solder mask pattern is completed in the same way. The processing parameters are as follows:

[0140] Power / W Frequency / kHz Pulse width / ns Processing speed / mm / s Processing times 6 200 20 600 1

[0141] The welding area was cleaned and welded using a UV picosecond laser. The processing parameters were as follows:

[0142] Power / W Frequency / kHz Pulse width / ps Processing speed / mm / s Processing times 10 1000 12 2000 1

[0143] (10) Solder 10 is added to the connection pad, and the component 11 is mounted and inserted, and then reflow soldering and selective wave soldering are performed.

[0144] The technical solutions disclosed and proposed by the present invention can be realized by those skilled in the art by referring to the contents of this article and appropriately changing the conditions, routes and other links. Although the methods and preparation techniques of the present invention have been described through preferred embodiments, relevant technicians can obviously modify or re-combine the methods and technical routes described herein without departing from the content, spirit and scope of the present invention to realize the final preparation technology. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the spirit, scope and content of the present invention.

Claims

1. A method for manufacturing a circuit board by laser processing of electroplating holes and resist patterns, characterized in that: Drill holes and deposit a thin metal layer on the holes and board surface, apply a non-photosensitive masking film, laser remove the masking layer covering the hole wall to expose the hole wall, only electroplate to thicken the conductive layer in the hole, only electroplate metal anti-corrosion agent in the hole, then use laser to make anti-corrosion pattern, etch to make conductive pattern, apply non-photosensitive solder resist on non-circuit area, use laser to make solder resist pattern at assembly site or bare board manufacturing site, and clean and treat the surface of welding area for solderability; The steps are: (1) Depositing an initial conductive layer on a double-sided, multi-layer circuit board in production after drilling, and electroplating copper to a thickness that can withstand subsequent processes; (2) A non-photosensitive organic film is attached to the board surface as an anti-electroplating masking film. The non-photosensitive organic film is composed of several layers of different forms and compositions. The layer in contact with the circuit board has viscosity and fluidity, and has anti-plating / anti-etching properties, and anti-welding / anti-soldering properties. The anti-electroplating masking film covering the circuit area does not need to be removed. As a solder mask for the circuit area, its technical route includes depositing non-photosensitive organic film-forming materials on the board surface and hole wall by electrophoresis, vacuum coating, vapor deposition, etc.; (3) using a laser to remove the masking material covering the hole wall area to produce an anti-plating pattern, and using a laser to remove the anti-plating masking film layer on the surface of the clamping point of the electroplating fixture to expose the copper surface in the contact area with the electroplating fixture; (4) Electroplating, depositing copper on the hole wall to thicken the conductive layer to the thickness required for final inspection; (5) Electroplating, depositing corrosion-resistant and weldable metal on the hole wall; (6) using a laser to remove the organic film material on the non-circuit area to expose the non-circuit copper and obtain an anti-etching masking pattern. When using a laser to remove the anti-electroplating masking film on the non-circuit area, when the ratio of the perimeter of the area to be removed to the diameter of the focused laser beam is less than 10, the masking film on the surface of the substrate and the conductive metal copper thereunder are removed by point-by-point and line-by-line photolithography using a focused laser beam. When the ratio of the perimeter of the area to be removed to the diameter of the focused laser beam is greater than 15, firstly, using a focused laser beam along the inner side of the envelope of the area to be removed and using the envelope as the boundary, the masking film on the surface of the substrate and the conductive metal copper thereunder are removed by point-by-point photolithography until a closed adiabatic channel is formed around the unremoved portion of the area, and then using a laser beam with a lower optical power density than the minimum optical power density required to remove the metal copper but with a larger diameter to heat the unremoved area, so that the anti-electroplating masking film thereon and the conductive metal copper thereunder are simultaneously separated from the surface of the substrate and removed; (7) chemical etching to remove copper from non-circuit areas to obtain a conductive pattern; (8) Applying non-photosensitive solder resist to non-circuit areas and curing them at one time, wherein the coating method includes spray printing and screen printing; the coating thickness is such that after curing, it is flush with the masking film on the circuit or as required by the design; (9) Use laser to remove organic materials on the conductors in the welding area at the assembly site or bare board manufacturing site, create solder mask patterns, and clean and treat the surface of the welding area for solderability; (10) Add solder to the connection pad, mount and insert components, and perform reflow soldering and / or wave soldering.

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