A method for processing electroplating holes and circuit masks by laser and etching circuit boards

Abstract

The present invention relates to a method for manufacturing a circuit board by using a laser to process a plating hole and a circuit mask respectively, and etching the hole and the board surface, drilling holes and depositing a thin metal layer in the hole and the board surface, attaching a non-photosensitive masking film, and removing the masking layer covering the hole wall by laser to expose the hole wall, and then only plating and thickening the conductive layer in the hole, and then using a laser to make a resist pattern of the circuit part, and pattern-plating copper and metal resist, and etching to make a conductive pattern; 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. Using non-photosensitive materials as anti-plating materials can reduce costs; plating holes and circuits differently, and the thickness of the plating layer can be easily controlled; using lasers to manufacture plating hole patterns and plating circuit patterns in steps, with fewer steps. The present invention is suitable for mass production of various circuit boards, and is also suitable for circuit board samples and small batch, multi-variety production.

Description

Technical Field

[0001] The present invention relates to a method for using laser to process electroplating holes and circuit masks respectively and to etch and manufacture circuit boards. The method uses laser to directly remove mask materials step by step to manufacture patterns of only electroplated hole walls, and then simultaneously electroplates hole walls and circuit patterns, and then, electroplates hole walls and circuits differently, and then, etches to manufacture conductive patterns. The method belongs to the technical field of circuit board manufacturing. Background Art

[0002] The present invention relates to a method for manufacturing a circuit board by using laser direct material removal technology, electroplating hole walls and circuits differently, and etching to manufacture conductive patterns without a pattern transfer process.

[0003] The manufacturing process is as follows: depositing an initial conductive layer on the semi-finished product of the double-sided, multi-layer circuit board with completed drilling, chemically plating or electroplating thin copper → pasting an anti-plating masking film → making a pattern on the electroplated hole wall, laser removing the anti-plating masking film layer on the hole area, opening a window for the liquid to enter the hole → electroplating, depositing copper on the hole wall to thicken the hole wall → laser removing the anti-plating masking film layer on the pad and line area, adding pads and line plating windows on the hole plating windows → electroplating, and depositing copper and anti-corrosion metal on the pads, lines and hole walls at the same time → laser removing the anti-plating masking film in the non-line area → etching to remove the copper foil in the non-line area to make a conductive pattern → laser removing the anti-corrosion metal layer on the hole wall, pads and lines → coating the entire board with and curing the solder resist material at one time → using a laser to remove the organic material on the conductor in the welding area at the assembly site to make a solder resist pattern, and cleaning and solderability treatment of the welding area surface → adding solder to the connection pad, mounting and inserting components, and performing remelting soldering and / or wave soldering.

[0004] 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-flexible boards. The present invention uses laser processing technology and the same mask to separately make patterns of only electroplating hole walls and patterns of simultaneously electroplating hole walls, pads, and circuits. The copper thickness of the hole walls and the copper thickness of the circuits can be controlled separately, and the electrical requirements of electronic products on circuit boards can be better met. The present invention is suitable for small-batch and multi-variety production of circuit boards, and is also suitable for batch manufacturing of circuit boards.

[0005] 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 also the installation and fixing carrier of various components and the skeleton of the product.

[0006] 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 the 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.

[0007] 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.

[0008] 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 inter-layer electrical interconnection indicators. 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:

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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 and selectively electroplate thickened lines.

[0016] 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. Summary of the invention

[0017] In view of the deficiency of the prior art that the thickened holes and circuits cannot be plated separately, the present invention has developed a new manufacturing method. The technical solution of the present invention is as follows:

[0018] A method for manufacturing a circuit board by using laser to process electroplating holes and circuit masks respectively, and etching to make a circuit board, drilling holes and depositing a thin metal layer on the holes and the board surface, pasting 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, and then using laser to make a circuit part anti-plating pattern, and pattern electroplating copper and metal resist, and etching to make a conductive pattern; the steps are:

[0019] (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;

[0020] (2) Affixing a non-photosensitive organic film to the board surface as an anti-plating masking film;

[0021] (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;

[0022] (4) electroplating, depositing copper on the hole wall to thicken the conductive layer to the required thickness;

[0023] (5) Use laser to remove the anti-plating masking film layer on the pad area and the circuit area, and add the plating window of the pad and circuit area on the hole plating window;

[0024] (6) Electroplating, depositing copper on the hole wall, pad and circuit to the required thickness for final inspection;

[0025] (7) Electroplating, depositing corrosion-resistant metal on the hole wall, pad and circuit at the same time;

[0026] (8) Use laser to remove the anti-plating masking film on the non-circuit area;

[0027] (9) chemical etching to remove copper from non-circuit areas to obtain a conductive pattern;

[0028] (10) Use laser to remove the corrosion-resistant metal layer on the hole wall, pad and circuit;

[0029] (11) Full board coating and one-time curing of solder resist material;

[0030] (12) 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;

[0031] (13) Add solder to the connection pads, mount and insert components, and perform reflow soldering and / or wave soldering.

[0032] 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.

[0033] 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.

[0034] The step (9) includes removing the copper conductive pattern in the circuit area by laser.

[0035] The step (10) includes removing the anti-corrosion metal layer on the hole wall, the pad and the circuit by chemical means.

[0036] The step (11) comprises attaching a dry photosensitive film and a dry non-photosensitive film under a certain pressure and temperature.

[0037] The step (11) or (12) further comprises removing organic materials on the conductors in the welding area by laser at the bare board manufacturing site, manufacturing a solder resist pattern, and cleaning the surface of the welding area.

[0038] The step (11) or (12) further includes continuing the circuit board manufacturing process at the bare board manufacturing site using existing technology and materials.

[0039] The present invention is a method for using laser to process electroplating holes and circuit masks separately and to etch circuit boards. After chemical copper plating or electroplating thin copper, a non-photosensitive anti-plating mask is attached, and the mask material is directly removed step by step by laser to form a pattern of only electroplating hole walls, and then the hole walls and circuit patterns are electroplated simultaneously, the hole walls and circuits are electroplated differently, and then, a conductive pattern is manufactured by etching.

[0040] Step (1) deposits an initial conductive layer on the finished product of the double-sided, multi-layer circuit board after drilling, and electroplates copper to a thickness that can withstand subsequent processes. The purpose of making a thin copper on the initial conductive layer is to increase the reliability of the process, and its thickness can reach the lower limit of ensuring process reliability, for example, after traditional chemical copper deposition, or after black hole formation using a carbon film method, electroplating 1μm-5μm thin copper.

[0041] Step (2) affixing a non-photosensitive organic film to the board surface as an anti-plating masking film. The prior art generally uses a 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 an adhesive and a photopolymerizable monomer, etc. 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 relatively thick, generally above 20 μm. The resolution is limited and the masking effect is poor. The masking film of the present invention does not need to have photosensitive properties. A general pre-coated pressure-sensitive coating film or a heat-sensitive coating film can meet the requirements. The film is hot-pressed and directly removed by laser to form a pattern. The process is simple. Moreover, the film has high resolution, low price, high strength, good masking ability, can be removed in steps, and can withstand multiple electroplating processes. For example, a 20 μm thick heat-sensitive PI, PVC, PC, PET, or PP film can be hot-pressed as an anti-plating mask. Parylene can also be used as an anti-plating mask.

[0042] The anti-plating masking film includes a dry film made of single-component, multi-component, composite thermosetting, photosetting, heat-pressing attachable, photosensitive and non-photosensitive materials, and its thickness is greater than the total metal thickness thickened on the circuit, ranging from 2μm to 1000μm. It is preferably a thermosetting dry film that can be heat-pressed and has solder resistance, and the preferred film thickness is 5μm-500μm.

[0043] 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.

[0044] 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.

[0045] Step (3) uses a laser to remove the masking material covering the hole wall area to produce an anti-electroplating pattern, and uses a laser to remove the anti-electroplating masking film layer on the surface of the clamping point of the electroplating fixture to expose the copper surface of the contact area with the electroplating fixture. The laser removes the anti-electroplating 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 by ring cutting into blocks 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, so as to increase the conductive area area, disperse the electric lines, and form a pattern that is conducive to the balanced electroplating process of the plated hole wall.

[0046] 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.

[0047] When using a laser to remove an anti-plating mask film, the focused laser light power density should be set to a level greater than the minimum power density required to remove the material, for example, greater than 1.2 times the minimum light power density required for the material, but lower than or close to the minimum light power density required to remove the underlying metal copper layer.

[0048] Step (4) electroplating, depositing copper on the hole wall to thicken the conductive layer to the required thickness. The control point of this step is the electroplating time. At this time, all areas on the board surface except the hole wall and the electroplating balance block 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.

[0049] Step (5) Use laser to remove the anti-plating masking film layer on the pad area and the circuit area, and add a plating window for the pad and circuit area on the hole plating window.

[0050] Step (6) electroplating, and copper is deposited on the hole wall, pad and circuit to the thickness required for final inspection. The control point of this step process is the electroplating time. The current circuit board manufacturing technology generally uses photosensitive dry film as an anti-electroplating mask. The material is mostly UV-curable. The thickness of the masking pattern formed is within a certain range and cannot be too thin or too thick. Because the material is cross-linked and polymerized during hot pressing and UV exposure to form a mask, it must be able to be easily decomposed by a de-filming chemical solution later. Therefore, the mask produced by such technology can only be an imperfect sub-solid to some extent. If it is too thick, the resolution is low, and the required exposure is large. On the one hand, the thin layer close to the light source is overexposed, and on the other hand, the thin layer far from the light source is underexposed. If the sub-solid material, which is originally fragile, is too thin, it will not reach the mechanical strength required for masking, resulting in infiltration.

[0051] The present invention uses laser to directly remove and manufacture masking patterns, and non-photosensitive materials can be used. The material itself is a fully polymerized solid, and has sufficient masking ability regardless of thickness. Even if the electroplating time is long, it will not fall off or dissolve. For circuit boards that require thicker circuit copper, a thicker material can be selected in step (2), for example, a mask with a thickness of 300 μm is selected. After the mask material on the surface of the required circuit is removed by laser, the electroplating time is controlled until the thickness of the single metal or multiple metal coating approaches or reaches 300 μm.

[0052] Step (7) electroplating, while depositing corrosion-resistant metal on the hole wall, pad and circuit; this step is to electroplate tin, nickel, gold and other solderability protective metals in the hole, pad and circuit after pattern electroplating, as a corrosion-resistant layer for chemical etching.

[0053] Step (8) uses laser to remove the anti-plating masking film on the non-circuit area; when using laser to remove the anti-plating 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 small, preferably 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 large, preferably greater than 15, the masking film on the surface of the substrate and the conductive metal copper thereunder 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 using 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 is used to heat the unremoved area, so that the anti-plating masking film thereon and the conductive metal copper thereunder are simultaneously detached from the substrate surface and removed.

[0054] 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.

[0055] Step (9) chemically etching to remove copper on non-circuit areas to obtain a conductive pattern;

[0056] 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.

[0057] 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 (9) and before (10). 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 organization and management is small; the advantage is that the process problems can be discovered in time, and the cost of repairing or scrapping the problem board is low.

[0058] Step (10) uses laser to remove the anti-corrosion metal layer on the hole wall, the pad and the circuit. This step also includes removing the anti-corrosion metal layer on the hole wall, the pad and the circuit by chemical means.

[0059] The step (10) includes removing the anti-corrosion metal layer on the hole wall, the pad and the circuit by chemical means.

[0060] Step (11) coating the entire board with solder resist material and curing it at one time.

[0061] Step (11) includes attaching a dry photosensitive film and a dry non-photosensitive film under a certain pressure and temperature.

[0062] 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.

[0063] The step (11) includes removing organic materials on the conductors in the welding area by laser at the bare board manufacturing site, manufacturing a solder mask pattern, and cleaning the surface of the welding area. It also includes continuing the circuit board manufacturing process at the bare board manufacturing site using existing technology and materials.

[0064] Step (12) uses a laser to remove organic materials on the conductor of the welding area at the assembly site to produce a solder resist pattern, and cleans and treats the surface of the welding area for solderability. This step can be completed in one step on the same equipment, or it can be performed 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 to produce a solder resist pattern and generate a welding area; the second step: cleaning and treating the surface of the welding area for solderability, 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, expose a fresh metal surface, and produce solderability that is easily wetted by molten solder.

[0065] The step (12) includes removing organic materials on the conductors in the welding area by laser at the bare board manufacturing site, manufacturing a solder resist pattern, and cleaning the surface of the welding area.

[0066] The step (12) also includes continuing the circuit board manufacturing process at the bare board manufacturing site using existing technologies and materials.

[0067] Step (13) adds solder to the connection pad, performs component mounting and insertion, performs remelting soldering and / or wave soldering. In the method of the present invention, since the solderable coating layer of the welding area is replaced by the fresh copper surface treated by laser, after the completion of step (12), step (13) should be performed in the shortest possible time to avoid oxidation of the connection pad surface, and complete the component assembly under the condition of excellent solderability after laser treatment, including performing component insertion and directly applying solder to the laser treated welding area to complete component welding; or directly printing solder paste on the laser treated welding area, and then performing component mounting and reflow soldering; or assembling components according to other technologies.

[0068] 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. Using non-photosensitive materials as anti-plating materials reduces costs; differentiating the plating holes and lines makes it easy to control the thickness of the plating layer; using lasers to manufacture the plating hole patterns and plating line patterns in steps, with fewer steps. The present invention is suitable for mass production of various circuit boards, and is also suitable for circuit board samples and small batch, multi-variety production.

[0069] The advantages and effects of the present invention are:

[0070] 1. The present invention can selectively electroplate holes and circuits, and the coating thickness can be easily controlled. In particular, only thickened holes can be electroplated, which can solve the problem of thin coating thickness on the hole wall and the problem of inconsistency between the coating thickness on the hole wall and the copper plating thickness on the circuit.

[0071] 2. The present invention uses a laser direct removal method to manufacture electroplated hole walls and electroplated circuit patterns. Non-photosensitive materials can be used as anti-plating materials to reduce costs. In addition, the electroplating resistance is good, and thicker hole wall conductive layers and circuit conductive layers can be manufactured.

[0072] 3. The present invention realizes electroplating of only holes and circuits, and the thickness of the conductive layer of the non-circuit part does not increase. It is suitable for using laser to directly remove the copper foil of the non-circuit part to manufacture conductive patterns. There is no need to remove the anti-plating material, and the steps are few, so that more sophisticated conductive patterns can be manufactured.

[0073] 4. The present invention uses a film pre-coated with a heat-sensitive and 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 and clean welding areas and perform solderability treatment, which is more efficient and has better treatment effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 : Process flow chart of embodiment 1;

[0075] Figure 2 : Process flow chart of embodiment 2;

[0076] Wherein: 1. Insulating substrate 2. Copper layer of copper clad plate 3. Initial conductive layer 4. Electroplated thin copper 5. Anti-electroplating masking film 6. Electroplated layer on hole wall 7. Electroplated copper layer on hole wall, pad and circuit 8. Anti-corrosion metal layer on hole wall, pad and circuit 9. Solder resist material layer 10. Solder 11. Components

[0077] In the attached drawings, each letter A\B\C\D\E\F\G\H\I\J\K corresponds to a partial enlarged schematic diagram of each step. DETAILED DESCRIPTION

[0078] 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.

[0079] Example 1

[0080] 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.

[0081] This embodiment takes a double-sided printed circuit board as an example, and the specific processing steps are as follows:

[0082] (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.

[0083] 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.

[0084] Chemical copper is deposited on the double-sided board after drilling, and copper is electroplated. Specifically, the double-sided board after drilling is brushed to remove the burrs at the hole mouth and clean the board surface. Then copper is electroplated normally, with electroplating parameters: 10ASF*30min, thickness of about 5um.

[0085] (2) A non-photosensitive polymer film is attached to the board surface as an anti-plating masking film 5.

[0086] 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.

[0087] The anti-plating masking film includes a dry film made of single-component, multi-component, composite thermosetting, photosetting, heat-pressing attachable, photosensitive and non-photosensitive materials, and its thickness is greater than the total metal thickness thickened on the circuit, ranging from 2μm to 1000μm. It is preferably a thermosetting dry film that can be heat-pressed and has solder resistance, and the preferred film thickness is 5μm-500μm.

[0088] Specifically, the double-sided copper-plated board is brushed, the double-sided board surface is roughened and cleaned, and the bonding strength between the copper surface and the polymer film to be bonded is enhanced. Then, the BOPET polymer film with anti-electroplating performance is hot-pressed on the double-sided copper-clad board by a film laminating machine, with a thickness of 10um and laminating parameters: pressure 10kg / cm 2 , temperature 90℃, speed 0.1m / min.

[0089] (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. Use laser to remove the anti-plating masking film layer on the hole area to open a window for the liquid to enter the hole.

[0090] In order to solve the problems of too small plating area, uneven distribution of electric lines, and difficult control of current density when electroplating hole walls, laser is used to remove dead copper areas with no electrical function in non-circuit parts when making hole wall electroplating patterns, increase the conductive area, and disperse the electric lines.

[0091] Specifically, this embodiment uses a 20W ultraviolet nanosecond laser machine to remove the BOPET 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 BOPET 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:

[0092] Power / W Frequency / kHz Pulse width / ns Processing speed / mm / s Processing times 5 150 20 800 1

[0093] (4) Electroplating: depositing copper on the hole wall to thicken the conductive layer to a required thickness, forming a hole wall electroplating layer 6.

[0094] 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.

[0095] Specifically, due to the small electroplating area, this step adopts a small current density for electroplating, and the electroplating parameters are: 10ASF*50min, and the coating thickness is about 15um.

[0096] (5) Use laser to remove the anti-plating masking film layer on the pad area and the circuit area, and add plating windows for the pad and circuit area on the hole plating windows.

[0097] Specifically, the processing method and processing parameters are the same as step (3).

[0098] (6) Electroplating: depositing copper on the hole wall, pad and circuit to the required thickness for final inspection, forming an electroplated copper layer 7 on the hole wall, pad and circuit.

[0099] The control point of this step is the electroplating time. The current circuit board manufacturing technology generally uses photo-induced dry film as an anti-electroplating mask. The material is mostly UV-curable. The thickness of the masking pattern formed is within a certain range, and it cannot be too thin or too thick. Because the material is cross-linked and polymerized during hot pressing and UV exposure to become a mask, and it must be able to be easily decomposed by the film removal chemical solution later, the mask produced by such technology can only be an imperfect sub-solid to some extent. If it is too thick, the resolution is low, and the required exposure is large, there will be a phenomenon that the thin layer close to the light source is overexposed on the one hand, and the thin layer far away from the light source is underexposed on the other hand; if the sub-solid material, which is already fragile, is too thin, it will not reach the mechanical strength required for masking, resulting in infiltration.

[0100] The present invention uses laser to directly remove and manufacture masking patterns, and non-photosensitive materials can be used. The material itself is a fully polymerized solid, and has sufficient masking ability regardless of thickness. Even if the electroplating time is long, it will not fall off or dissolve. For circuit boards that require thicker circuit copper, a thicker material can be selected in step (2), for example, a mask with a thickness of 300 μm is selected. After the mask material on the surface of the required circuit is removed by laser, the electroplating time is controlled until the thickness of the single metal or multiple metal coating approaches or reaches 300 μm.

[0101] Specifically, this step is to perform electroplating on the hole wall, the pad and the circuit, and the electroplating copper parameters are: 12ASF*60min, and the plating thickness is about 20um.

[0102] (7) Electroplating, depositing corrosion-resistant metal on the hole wall, pad and circuit at the same time, forming a corrosion-resistant metal layer 8 on the hole wall, pad and circuit; this step is to electroplate tin, nickel gold and other solderable protective metals in the hole, pad and circuit after pattern electroplating, as a corrosion-resistant layer for chemical etching.

[0103] Specifically, after the copper electroplating in step (6) is completed, tin is electroplated on the hole wall, the pad and the circuit as an anti-corrosion layer. Tin plating parameters: 0.1ASD*30min, the plating thickness is about 5um.

[0104] (8) Using laser to remove the anti-plating masking film on the non-circuit area; when using laser to remove the anti-plating 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 small, preferably less than 10, use the focused laser beam to adopt point-by-point and line-by-line photolithography to remove the masking film on the surface of the substrate and the conductive metal copper underneath; 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, first use the focused laser beam along the inner side of the envelope of the area to be removed and use the envelope as the boundary to remove the masking film on the surface of the substrate and the conductive metal copper underneath point-by-point photolithography until a closed adiabatic channel is formed around the unremoved portion of the area, and then use a laser beam with a diameter lower than the minimum optical power density required to remove the metal copper but larger to heat the unremoved area, so that the anti-plating masking film on it and the conductive metal copper underneath are simultaneously separated from the substrate surface and removed.

[0105] 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.

[0106] The BOPET anti-plating masking film on the non-circuit area is removed by laser. Specifically, the processing method and processing parameters are the same as step (3).

[0107] (9) chemical etching to remove copper from non-circuit areas to obtain a conductive pattern;

[0108] 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.

[0109] 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 (9) and before (10). 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 organization and management is small; the advantage is that the process problems can be discovered in time, and the cost of repairing or scrapping the problem board is low.

[0110] (10) Use laser to remove the electroplated tin layer on the hole wall, pad and circuit.

[0111] Specifically, this embodiment uses a 50W infrared nanosecond laser machine to remove the electroplated tin layer on the hole wall, the pad and the circuit. The processing parameters are as follows:

[0112] Power / W Frequency / kHz Pulse width / ns Processing speed / mm / s Processing times Remark 30 150 100 1200 1 Negative defocus 0.5mm

[0113] (11) The solder resist material is coated on the entire board and cured at one time to form a solder resist material layer 9. The prior art generally uses liquid photosensitive ink as a solder resist. The solder resist contains adhesives and photopolymerizable monomers. The pattern forming process is very complicated and requires multiple steps such as coating, pre-baking, exposure, development, and curing. Moreover, it is expensive and has low resolution. It 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 the components are assembled, and the process is simple. For example, a heat-sensitive PI, PVC, PC, PET, or PP film with a thickness of 20μm-200μm is used as a solder resist, and parylene can also be used as a solder resist.

[0114] Specifically, the KSM-386 thermosetting ink produced by Suzhou Guangxin Photosensitive New Materials Co., Ltd. is printed on the non-circuit area of ​​the double-sided board by screen printing and fully cured at one time. The curing conditions are: 150°C*30min, and the thickness of the solder resist ink is about 20um.

[0115] (12) At the assembly site, a laser is used to remove organic materials on the conductors of the welding area to produce a solder resist pattern, and the surface of the welding area is cleaned and treated for solderability. This step can be completed in one step on the same equipment, or it can be performed 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 to produce a solder resist pattern and generate a welding area; the second step is to clean the surface of the welding area and treat the solderability, using another laser to remove the solder resist residues 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.

[0116] Specifically, this embodiment first uses a 20W infrared nanosecond laser machine to remove the solder resist ink in the welding area, places the circuit board on the laser equipment adsorption table, imports the engineering data of laser processing, accurately aligns the circuit board with the processing data, and removes the solder resist ink by laser photoetching. After the top surface processing is completed, turn the circuit board over, and use the same method to remove the film on the bottom surface of the copper clad board. The processing parameters are as follows:

[0117] Power / W Frequency / kHz Pulse width / ns Processing speed / mm / s Processing times 6 200 100 1000 1

[0118] Then, a UV picosecond laser with lower single pulse energy was used to clean and treat the weld area. The processing parameters were as follows:

[0119] Power / W Frequency / kHz Pulse width / ps Processing speed / mm / s Processing times 10 1000 12 2000 1

[0120] (13) Add solder 10 to the connection pad, mount and insert the component 11, and perform reflow soldering and / or wave soldering. In the method of the present invention, since the solderable coating layer of the welding area is replaced by the fresh copper surface treated by laser, after the completion of step (12), step (13) should be performed in the shortest possible time to avoid oxidation of the connection pad surface, and complete the component assembly under the condition of excellent solderability after laser treatment, including inserting components and directly applying solder to the laser treated welding area to complete component welding; or directly printing solder paste on the laser treated welding area, and then mounting components and reflow soldering; or assembling components according to other technologies.

[0121] Example 2

[0122] 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.

[0123] This embodiment takes a four-layer circuit board that has been drilled and has completed inner layer circuit production as an example, and the specific processing steps are as follows:

[0124] (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 four-layer circuit board after drilling. Copper is electroplated to a thickness that can withstand subsequent processes, thereby forming an electroplated thin copper 4.

[0125] The purpose of making thin copper on the initial conductive layer is to increase the reliability of the process. Its thickness can reach the lower limit of ensuring the reliability of the process. Specifically, the circuit board with holes drilled is brushed to remove the burrs at the hole mouth and clean the board surface. Then, copper electroplating is carried out after removing the glue residue. The electroplating parameters are: 10ASF*35min, and the coating thickness is about 5um.

[0126] (2) A non-photosensitive polymer film is attached to the board surface as an anti-plating masking film 5.

[0127] Specifically, the four-layer circuit board after thin copper electroplating is brushed and dried, and then hot-pressed with anti-electroplating polymer film BOPP, the film thickness is 10um, and the bonding parameters are: pressure 15kg / cm 2 , temperature 100℃, speed 0.1m / min.

[0128] (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.

[0129] Specifically, this embodiment uses a 20W ultraviolet nanosecond laser machine to remove the BOPP 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 BOPP 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:

[0130] Power / W Frequency / kHz Pulse width / ns Processing speed / mm / s Processing times 6 200 20 600 1

[0131] (4) Electroplating: depositing copper on the hole wall to thicken the conductive layer to a required thickness to form a hole electroplating layer 6.

[0132] 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.

[0133] Specifically, since the electroplating area is small, a small current density is used for electroplating in this step, and the electroplating parameters are: 10ASF*60min, and the coating thickness is about 15um.

[0134] (5) Use laser to remove the anti-plating masking film on the non-circuit area;

[0135] Specifically, the processing method and processing parameters are the same as step (3).

[0136] (6) Electroplating: depositing copper on the hole wall, pad and circuit to the required thickness for final inspection and adding other metals to form an electroplated copper layer 7 on the hole wall, pad and circuit.

[0137] This step is to perform pattern electroplating on the hole wall, pad and circuit. The copper electroplating parameters are: 12ASF*70min, and the coating thickness is about 20um.

[0138] (7) Electroplating, depositing corrosion-resistant metal on the hole wall, pad and circuit at the same time, forming a corrosion-resistant metal layer 8 on the hole wall, pad and circuit; this step is to electroplate tin, nickel gold and other solderable protective metals in the hole, pad and circuit after pattern electroplating, as a corrosion-resistant layer for chemical etching.

[0139] Specifically, after the copper electroplating in step (6) is completed, tin is electroplated on the hole wall, the pad and the circuit as an anti-corrosion layer. Tin plating parameters: 0.1ASD*40min, the plating thickness is about 5um.

[0140] (8) Use laser to remove the anti-plating mask film on the non-circuit area.

[0141] Specifically, the BOPP anti-plating masking film on the four-layer circuit board is completely removed by laser, and the removal method and parameters are the same as step (3).

[0142] (9) Chemical etching removes the copper on the non-circuit area to obtain a conductive pattern.

[0143] 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.

[0144] (10) Use chemical methods to remove the electroplated tin layer on the hole wall, pad and circuit.

[0145] Use detinning water to remove the electroplated tin layer on the hole wall, pad and circuit.

[0146] (11) The solder resist material is coated on the entire board and cured at one time to form a solder resist material layer 9.

[0147] In this embodiment, a PI film is laminated on a 6-layer circuit board as a solder resist material. Specifically, a laminator is used to laminate the 6-layer circuit board and the PI film. The PI film is a Kapton HN film produced by DuPont with a thickness of 25um. During lamination, a silicone rubber pad is used as a thermal lamination pad. According to the material properties, the thermal lamination stages and parameters are as follows:

[0148] 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

[0149] (12) 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;

[0150] 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:

[0151] Power / W Frequency / kHz Pulse width / ns Processing speed / mm / s Processing times 6 200 20 600 1

[0152] The welding area was cleaned and welded using a UV picosecond laser. The processing parameters were as follows:

[0153] Power / W Frequency / kHz Pulse width / ps Processing speed / mm / s Processing times 10 1000 12 2000 1

[0154] (13) Solder 10 is added to the connection pad, and the component 11 is mounted and inserted, and reflow soldering and / or wave soldering are performed.

[0155] 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 processing electroplating holes, circuit masks and etching circuit boards by laser, characterized in that: A method for manufacturing a circuit board by drilling holes and depositing a thin metal layer in the holes and on the board surface as a starting conductive layer, attaching a non-photosensitive anti-plating masking film, removing the anti-plating masking film covering the hole wall with a laser to expose the hole wall, then only electroplating to thicken the conductive layer in the hole, and then using a laser to make a resist pattern for the circuit part, and pattern-plating copper and metal resist, and etching to make a conductive pattern; The steps are: (1) Depositing the initial conductive layer on the finished product of the double-sided or multi-layer circuit board with completed drilling, and electroplating copper to a thickness that can withstand subsequent processes; (2) Pasting a non-photosensitive organic film on the board surface as an anti-plating masking film, the masking film is composed of several layers of different shapes and components, among which the layer in contact with the circuit board has viscosity and fluidity; or using electrophoresis, vacuum coating or vapor deposition technology to deposit non-photosensitive organic film-forming materials on the board surface and hole wall; (3) using a laser to remove the anti-plating masking film covering the hole wall area to produce an anti-plating pattern, and using a laser to remove the anti-plating masking film 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 required thickness; (5) Use laser to remove the anti-plating masking film on the pad area and the circuit area, and add the plating window of the pad and circuit area on the hole plating window; (6) Electroplating, depositing copper on the hole wall, pad and circuit to the required thickness for final inspection; (7) Electroplating, depositing corrosion-resistant metal on the hole wall, pad and circuit as a metal resist; (8) Use laser to remove the anti-plating masking film on the non-circuit area; (9) Chemical etching removes copper from non-circuit areas to obtain a conductive pattern; (10) Use laser or chemical means to remove the corrosion-resistant metal on the hole wall, pad and circuit; (11) Full board coating and one-time curing of solder resist material, or use of non-photosensitive film in a dry state under certain pressure and temperature as solder resist material; (12) At the assembly site, the solder resist material on the conductive body of the welding area is removed by laser, the solder resist pattern is produced, and the surface of the welding area is cleaned and treated for solderability; or at the bare board manufacturing site, the solder resist material on the conductive body of the welding area is removed by laser, the solder resist pattern is produced, and the surface of the welding area is cleaned; (13) Add solder to the pads, mount and insert components, and perform reflow soldering and / or wave soldering.

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