X-shaped hole rapid filling electroplating process and device and electroplating liquid

Abstract

The invention relates to the technical field of electroplating processing, in particular to an X-shaped hole rapid filling electroplating process and device and electroplating liquid. The X-shaped hole rapid filling electroplating process comprises the following operation steps: S1, providing a printed circuit board; s2, arranging a dry film on the surface of the printed circuit board, and exposing and developing the dry film by using a film; and S3, electroplating and hole filling. According to the method, excessive plate surface electroplating is not involved, and only the independent X-shaped holes can be filled, so that the processing time is shortened, and a PCB workpiece with excellent quality is obtained; according to the method, the X-shaped hole with the maximum hole diameter of 20-200 microns, the hole depth of 40-500 microns and the thickness-diameter ratio of 0.5-5 is matched, rapid filling can be achieved, the filling speed can reach 100 microns / min or above, filling uniformity is good, and the depression degree is as low as 100 microns or below.

Description

Technical Field

[0001] The present invention relates to the technical field of electroplating processing, and particularly relates to a rapid filling electroplating process, device and electroplating solution for X-shaped holes. Background Art

[0002] In the current PCB (printed circuit board) electroplating copper industry, for the hole filling process of electroplating X-shaped holes on a PCB board, the conventional method is to perform a comprehensive hole filling treatment on the entire board surface, including X-shaped holes and vias. However, this method has some problems: on the one hand, a large amount of chemical reagents and energy are required during the electroplating copper process, which not only results in high costs but also causes serious environmental pollution. On the other hand, defects such as pinholes, pockmarks, and copper nodules are likely to occur on the board surface during the electroplating copper process, thus affecting the reliability of the PCB parts. In addition, during the electroplating copper process, copper plating needs to be performed on the board surface, which often leads to an overly thick copper plating layer and requires a copper thinning process, not only increasing the complexity of the process but also reducing the production efficiency.

[0003] With the miniaturization and high performance of electronic devices, the requirements for PCB boards are also getting higher and higher. As a new type of PCB hole type, X-shaped holes have higher wiring density and better signal transmission performance, showing broad application prospects and potential. However, there are some problems in the traditional electroplating copper process when filling X-shaped holes, such as slow filling speed resulting in long electroplating time, uneven filling reducing the overall board yield, and easy occurrence of hollows in the holes leading to defective scrapping. These problems not only affect the quality and performance of PCB parts but also increase the production cost and manufacturing cycle. To meet the current ESG (Environmental, Social, Governance) requirements, there is an urgent need for an environmentally friendly and low-pollution electroplating process that can match X-shaped holes.

[0004] Chinese Patent CN117568886A discloses a three-step electroplating copper method for filling X-shaped vias in an IC carrier board, which respectively adopts high, low, and medium current density sequences and is combined with low, high, and low jet flows to optimize the electroplating effect of filling X-shaped vias in the IC carrier board. Chinese Patent CN119243271A discloses an electroplating copper plating solution and its application for filling X-shaped holes in printed circuits, which uses three types of additives. Specifically, the first type of additive is selected from one or more of polyethylene glycol, polypropylene glycol, block copolymers of ethylene oxide and propylene oxide, the second type of additive is selected from one or more of sodium polydithiopropane sulfonate, sodium 3-mercapto-1-propane sulfonate, phenyl polydithiopropane sulfonate, 2-mercaptobenzimidazole, and the third type of additive is selected from one or more of 1-methyl-4-nitroimidazole, azathioprine, 6-mercaptopurine, 2-thioxanthine to improve the electroplating effect. However, these existing technologies have not effectively solved the above technical problems. Summary of the Invention

[0005] In view of the problems existing in the traditional electroplating copper process when filling X-shaped holes, the present invention proposes a process method and electroplating solution for rapid filling of X-shaped holes. By optimizing electroplating parameters and cooperating with a specific electroplating solution formulation (especially selecting specific additives), rapid filling is achieved for X-shaped holes with a hole diameter of 20 - 200 μm, a board thickness of 40 - 500 μm, and a thickness-to-diameter ratio of 0.5 - 5. The filling speed can reach more than 100 μm per minute. This technology not only ensures good filling uniformity, but also strictly controls the depression of the electroplated X-shaped holes within 10 μm, and there is no hollow phenomenon inside the holes, significantly enhancing the reliability and stability of the PCB board. In addition, this process method also has the remarkable advantages of simple operation, low cost, and easy realization of automated production.

[0006] In the first aspect of the present invention, a process for rapid filling electroplating of X-shaped holes is provided, and the operation steps include:

[0007] S1. Provide a printed circuit board;

[0008] S2. Set a dry film on the surface of the printed circuit board, and use a film to expose and develop the dry film;

[0009] S3. Electroplate and fill the holes;

[0010] The printed circuit board is provided with X-shaped holes (see Figure 1 schematic), and a conductive layer is provided on both the board surface and the inside of the X-shaped holes of the printed circuit board.

[0011] Preferably, the depth of the X-shaped holes is 40 - 500 μm, the maximum hole diameter at the hole opening is 20 - 200 μm, and the thickness-to-diameter ratio is 0.5 - 5.

[0012] In some embodiments, the number of X-shaped holes on the printed circuit board is greater than 1.

[0013] In some embodiments, the conductive layer may include any one of electroless metal layers, electroplated metal layers, and organic conductive layers.

[0014] Optionally, the electroless metal layer may include one or a composite electroless plating layer of electroless nickel layer, electroless copper layer, electroless tin layer, electroless cobalt layer, electroless silver layer, electroless gold layer, electroless palladium layer, electroless other precious metal layers (such as platinum); preferably an electroless copper layer.

[0015] Preferably, the thickness of the electroless metal layer is 0.05 - 25 μm, more preferably 0.1 - 1 μm.

[0016] Optionally, the electroplated metal layer may include, for example, an electrogalvanized layer, an electroplated nickel layer, an electroplated copper layer, an electroplated chromium layer, an electroplated tin layer, an electroplated cobalt layer, an electroplated silver layer, an electroplated gold layer, or a composite electroplated layer; preferably, it is an electroplated copper layer.

[0017] Preferably, the thickness of the electroplated metal layer is 0.5 - 6 μm.

[0018] Optionally, the organic conductive layer may include, for example, a conductive carbon layer, a conductive graphite layer, or a polymer conductive layer; among them, the conductive carbon layer and the conductive graphite layer can be obtained by a black hole process or a black shadow process; the polymer conductive layer can be obtained by selecting polymer compounds such as polyaniline, polythiophene, and polypyrrole as the matrix.

[0019] Optionally, a conductive layer is provided on the board surface and the bottom of the X-shaped hole of the printed circuit board, and no conductive layer is provided on the side wall of the X-shaped hole. The conductive layer can be obtained by a rolled copper layer or a chemical copper plating + flash plating process.

[0020] The film has an opening part, and the area of the opening part is greater than or equal to the maximum aperture of the X-shaped hole. Preferably, the shape of the opening part is circular, its diameter is denoted as D, and the maximum aperture of the X-shaped hole is denoted as H5, then (D - H5) ≥ 0 - 1000 μm. The diameter of the opening part can be used within this range.

[0021] In the present invention, a specific area (i.e., the opening part) is designed on the film. The opening part area is transparent or uncovered, so that in the subsequent manufacturing process, light, electroplating solution, or other processing media can pass through this area and act on the X-shaped hole area on the circuit board to achieve "opening the window" for the X-shaped hole. It is set that since the area of the opening part of the film is greater than or equal to the cross-sectional area of the X-shaped hole (i.e., the diameter of the opening part is greater than or equal to the maximum aperture of the X-shaped hole), after exposure and development, the edge of the X-shaped hole can only cover the hole edge or expose the hole edge by 0 - 10000 μm, ensuring that the copper ring at the hole opening can be exposed after filling during electroplating of the X-shaped hole, thus facilitating the completion of subsequent process operations. Through such a design, the circuit pattern and hole position on the printed circuit board can be precisely controlled during production, ensuring the manufacturing quality and performance of the circuit board.

[0022] Further, a dry film on the surface of the printed circuit board is developed and exposed through a film provided with an opening part. When light irradiates the dry film through the opening part of the film, the dry film part irradiated by the light undergoes a chemical change, and these dry film parts that have undergone chemical changes are removed in the developing step, so that the copper layers at the X-shaped holes and the hole edge are exposed. And after development, the dry film in the area of the printed circuit board that is not exposed by the opening part of the film remains, and these remaining dry film parts can play a masking role for the conductive layer on the surface of the printed circuit board and the hole edge of the X-shaped hole, avoiding unnecessary influence on the conductive layer on the surface of the printed circuit board in subsequent electroplating or other processing steps.

[0023] Preferably, in the step S3, the printed circuit board is placed in an electroplating solution at 20 - 30 °C, and segmented direct current is used for electroplating to fill the holes.

[0024] Note: The temperature of the electroplating solution is controlled by the temperature of the plating bath.

[0025] More preferably, the temperature of the electroplating solution (i.e., the temperature of the plating bath) is 23 - 27 °C.

[0026] More preferably, the time for electroplating to fill the holes is 40 - 240 min, and more preferably 50 - 80 min.

[0027] More preferably, the current density of the segmented direct current is 50 - 30 ASF, and more preferably 5 - 20 ASF.

[0028] The operation process of the present invention can completely fill the X-shaped holes with a hole depth of 40 - 500 μm, a maximum hole diameter of 20 - 200 μm, and a thickness-to-diameter ratio in the range of 0.5 - 5. After electroplating to fill the holes in the step S3, the depression (dimple) of the plating layer < 10 μm, and there is no hollow in the hole. The surface of the plated part after filling the X-shaped holes by the present invention is flat and has good uniformity.

[0029] The present invention has studied and compared different types of PCB manufacturing methods, such as Figure 5 The flow schematic diagrams of the subtractive method, semi-additive process (SAP), and modified semi-additive process (mSAP) are shown. Among them, line A is the subtractive process, line B is the SAP process, and line C is the mSAP process; the specific descriptions of the three process methods are as follows.

[0030] Such as Figure 5The process flow shown by the middle line A is the subtractive process flow. The processing path includes the whole board a → drilling b → electroless copper c → full-board electroplated copper d → dry film lamination e → exposure / development f → etching and copper removal g → film stripping h. Specifically, first, the whole-board electroless copper plating process is carried out on the copper clad laminate, and then the dry film is laminated. The circuit and X-shaped holes are protected through pattern transfer, and the unnecessary copper foil is etched away, that is, only the copper in the circuit and X-shaped holes is left. More specifically, first, the entire copper clad laminate 501 is drilled to form circuit holes (corresponding to the X-shaped holes 502 set in step b), and then electroless copper plating is carried out (step c) to deposit a layer of electroless copper layer 503 on both the circuit board surface and inside the X-shaped holes to form a conductive foundation. Then, the whole board is electroplated with copper to cover the inside of the whole-board X-shaped holes with an electroplated copper layer 504 for subsequent formation of the conductive path (step d). Subsequently, a dry film 505 is laminated on the surface of the printed circuit board (step e), and the circuit pattern is transferred to the dry film through exposure and development (step f). Next, the unnecessary copper foil is removed through the etching process (step g), and the copper in the circuit and X-shaped holes is retained. Finally, the film stripping step is completed (step h), thus obtaining the final PCB product.

[0031] As Figure 5 The process flow shown by the middle line B is the SAP process flow. The processing path includes the whole board a → drilling b → electroless copper c → dry film lamination i → exposure / development j → pattern electroplating k → film stripping / flash etching l. Specifically, circuit exposure is carried out on the insulating substrate containing a photosensitive catalyst, and then selective electroless copper deposition is carried out on the exposed circuit to obtain a complete PCB. More specifically, first, the entire copper clad laminate 501 is drilled to form circuit holes (corresponding to the X-shaped holes 502 set in step b), and then electroless copper plating is carried out (step c) to deposit a layer of electroless copper layer 503 on both the circuit board surface and inside the holes to form a conductive foundation. Then, the dry film 505 is laminated (step i), and the pattern on the dry film is transferred to the copper plate through exposure and development (step j) to define the circuit pattern. Further pattern electroplating is carried out (step k) to ensure that both the circuit holes and the circuit are evenly covered with copper 504. Finally, the excess copper is removed through film stripping and flash etching (step l), and the precise circuit pattern is retained, thus obtaining the final PCB product.

[0032] As Figure 5The middle route C shows the mSAP process. The processing path includes the whole board a → drilling b → electroless copper c → flash copper plating m → dry film lamination n → exposure / development o → pattern electroplating p → film stripping / flash etching q. Specifically, on the pre-treated substrate (copper-clad), the areas that do not need to be electroplated are protected (outer layer circuit process), and then electroplating is carried out again. That is, the whole process requires electroplating copper twice, so it is called the modified semi-additive process. More specifically, first, the whole copper-clad laminate 501 is drilled to form circuit holes (corresponding to the X-shaped holes 502 set in step b), and then electroless copper plating (step c) is carried out to deposit a layer of electroless copper layer 503 on both the circuit board surface and the holes (this step is not shown in route C. In actual operation, in route C, after c → m, the electroless copper layer 503 has been covered by the flash copper plating layer 506, so 503 is not described in route C) to form a conductive base. Then, flash copper plating (step m) is carried out to form a thin copper layer 506 with fine copper layer crystals. Further, a dry film 505 is laminated (step n), and the pattern on the dry film is transferred to the copper plate through exposure and development (step o) to define the circuit pattern. Then, pattern electroplating (step p) is carried out to ensure that the circuit holes and lines are evenly covered with copper 504. Finally, the excess copper is removed through film stripping and flash etching (step q) to retain the precise circuit pattern, thereby obtaining the final PCB product.

[0033] The present invention compares the effects of different processing paths of these three processes in actual production. Among them, in the subtractive process, problems such as uneven edges and rough hole walls will occur during the etching process, resulting in poor edge quality of the final PCB. And due to the side etching effect of etching on the circuit, fine lines less than 50 μm cannot be prepared. Although the SAP process can better control the uniformity of the copper layer and the circuit during the pattern electroplating process, currently, SAP requires good adhesion to the resin, has high requirements for surface roughening treatment and improved electroless copper process, the adhesion of the produced circuits is poor, and there is a risk of poor explosion and delamination. In contrast, the mSAP process has excellent effects. On the one hand, the adhesion of the circuit is improved by flash copper plating, reducing electroplating defects; on the other hand, the uniformity of the copper layer and the precision of the circuit are improved by secondary electroplating, reducing edge defects, with less side etching, and fine lines above 10 μm can be produced; on the third hand, the circuit reliability is good, and at the same time, due to the setting of protection measures, the hole walls of the X-shaped holes are smoother, thereby improving the overall quality of the PCB. In addition, the mSAP process has less impact on the environment during the electroplating process, meeting the current ESG requirements for green manufacturing. Therefore, Figure 5 The mSAP process of the middle route C has more obvious advantages and can meet the requirements of high-quality PCB parts, which is the optimal process route selection of the present invention.

[0034] After the optimization of the above process, the present invention preferably includes the following specific steps in step S1:

[0035] S101. Drill holes in the printed circuit board substrate to form via holes (X-shaped holes);

[0036] S102. Conduct electroless copper plating on the drilled printed circuit board substrate so that both the board surface and the X-shaped holes of the printed circuit board substrate are plated with an electroless copper layer (i.e., a conductive layer);

[0037] S103. Perform flash copper plating on the printed circuit board substrate to form a thin copper layer with fine copper crystal grains, and obtain the printed circuit board for standby.

[0038] In some embodiments, the thickness of the electroless copper layer is 0.4 - 1.2 μm.

[0039] In some embodiments, the thickness of the thin copper layer formed by the flash copper plating operation is 0.5 - 6 μm, which is achieved by electroplating; preferably, the current density is 0.5 - 1.8 ASD, and the electroplating time is 5 - 30 min.

[0040] The electroless copper plating and flash copper plating operations of the present invention can be carried out according to the common methods and potions in the art.

[0041] The present invention has no special limitation on the printed circuit board substrate, and common components in the art can be used, such as copper clad laminates.

[0042] In some embodiments, the present invention does not specifically limit the printed circuit board used for the X-shaped via fast filling electroplating process. The material, circuit board type, specific outer layer pattern of the circuit board, and circuit board thickness of the printed circuit board can all be selected and adjusted according to actual needs.

[0043] Preferably, the printed circuit board includes a carrier board or a packaging substrate. The electroplating process described in the present invention is particularly suitable for the production and use of printed circuit boards (PCBs) and integrated circuit (IC) carrier boards in the field of advanced packaging. The second aspect of the present invention provides an X-shaped via fast filling electroplating device for implementing the above-mentioned X-shaped via fast filling electroplating process; the electroplating device includes:

[0044] A setting unit for setting a dry film on the surface of the printed circuit board provided with X-shaped holes;

[0045] An exposure and development unit for exposing and developing the dry film using a film;

[0046] An electroplating unit for electroplating and filling the X-shaped holes.

[0047] In some embodiments, the electroplating method of the electroplating unit is a vertical electroplating method or a horizontal electroplating method.

[0048] In the present invention, a dry film is provided on the surface of a printed circuit board provided with X-shaped holes through a setting unit, and an exposure and development unit is responsible for using a film to produce a film pattern that precisely corresponds to the blind holes of the circuit board and the clamping points of the electroplating fixture. This unit accurately aligns the film pattern and closely adheres it to the surface of the dry film, and then exposes the insulating dry film covering the parts that do not require copper electroplating. Further, the circuit board is rinsed with a developing solution to complete the development process. After development, the circuit board (such as an HDI, high-density interconnect circuit board) is subjected to water washing and drying treatments. After this series of exposure and development processes are completed, the printed circuit board is transferred to an electroplating unit for electroplating operations on the X-shaped holes.

[0049] The present invention does not particularly limit the anode used in the electroplating unit, as long as the electroplating purpose can be achieved; for example, an insoluble iridium-tantalum coated titanium anode or a soluble phosphor copper anode.

[0050] Preferably, the electroplating method of the electroplating unit is a vertical electroplating method; more preferably, it is a gantry vertical electroplating method or a VCP (vertical continuous electroplating) method.

[0051] The exposure and development operations of the present invention are carried out according to the common methods and common developing solutions in the art, as long as the exposure and development purposes can be achieved, without particular limitation.

[0052] The third aspect of the present invention provides an electroplating solution, which is used in the electroplating filling step of the X-shaped hole rapid filling electroplating process as described above or in the electroplating unit of the X-shaped hole rapid filling electroplating device as described above.

[0053] The preparation raw materials of the electroplating solution include: 30 - 100 mg / L of chloride ions, 20 - 120 g / L of acidic electrolyte, 150 - 260 g / L of copper ion salt, 0.5 - 6 mg / L of brightener, 10 - 50000 mg / L of inhibitor, 10 - 10000 mg / L of leveling agent, and a solvent; the solvent is deionized water.

[0054] More preferably, the preparation raw materials of the electroplating solution include: 40 - 80 mg / L of chloride ions, 30 - 50 g / L of acidic electrolyte, 210 - 250 g / L of copper ion salt, 0.5 - 3 mg / L of brightener, 50 - 5000 mg / L of inhibitor, 10 - 2000 mg / L of leveling agent, and a solvent; the solvent is deionized water.

[0055] Leveling agent:

[0056] The leveling agent is a nitrogen-containing organic compound, and the molar mass of the leveling agent is 200 - 20000 g / mol.

[0057] Preferably, the nitrogen-containing organic compound is a product formed by the polymerization of a fatty amine compound and a polyol glycidyl ether.

[0058] The fatty amine compound is an aliphatic primary diamine compound, and the aliphatic primary diamine compound includes one or a combination of more than one of ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, adipic diamide, 2-methyl-1,3-propanediamine, N-methyl-2,2'-diaminodiethylamine, N-ethyl-1,3-propanediamine, N-propyl-1,3-propanediamine, and N-acetyl-1,3-propanediamine.

[0059] Examples of the polyol glycidyl ether compound include ethylene glycol-1,2-diglycidyl ether, propylene glycol-1,2-diglycidyl ether, propylene glycol-1,3-diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-cyclohexanedimethanol glycidyl ether, bisphenol A-diglycidyl ether, tetrahydrophthalic acid diglycidyl ester, 1,5-pentanedithiol glycidyl ether, 1,2-cyclohexanediol diglycidyl ether, glycerol triglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, etc.

[0060] Preferably, the aliphatic primary diamine compound is N-methyl-2,2'-diaminodiethylamine.

[0061] The polyol glycidyl ether compound is a diol diglycidyl ether, and the diol diglycidyl ether includes one or a combination of more than one of 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-cyclohexanedimethanol glycidyl ether, bisphenol A-diglycidyl ether, tetrahydrophthalic acid diglycidyl ester, 1,5-pentanedithiol glycidyl ether, and 1,2-cyclohexanediol diglycidyl ether.

[0062] Preferably, the diol diglycidyl ether is 1,6-hexanediol diglycidyl ether.

[0063] The molar ratio of the aliphatic primary diamine compound to the diol diglycidyl ether is 0.25:(0.8 - 1).

[0064] In some embodiments, the nitrogen-containing organic compound is a product formed by polymerizing a fatty amine compound and a polyol glycidyl ether, including a tertiary amine polymer or its quaternized copolymer.

[0065] Preferably, the fatty amine compound and the polyol glycidyl ether undergo a chelation reaction at -5 to 105 °C to obtain a tertiary amine polymer.

[0066] The time of the chelation reaction is 1 to 12 h.

[0067] More preferably, the tertiary amine polymer undergoes a quaternization reaction in the presence of a halogenated hydrocarbon to obtain a quaternized copolymer.

[0068] The temperature of the quaternization reaction is 55 to 130 °C, and the time of the quaternization reaction is 4 to 18 h.

[0069] Preferably, the molar ratio of the tertiary amine polymer to the haloalkane is 1:(0.2 - 2).

[0070] In some embodiments, the haloalkane used for the quaternization reaction is not particularly limited, and examples include tert-butyl chloride, benzyl chloride, phenyl halides, etc.

[0071] Preferably, the phenyl halide is a phenyl halide containing a substituted or unsubstituted C1 - C4 alkyl group, and examples include o-chloroanisole, m-chloroanisole, p-chloroanisole, 2,4-dichloroanisole, 2,6-dichloroanisole.

[0072] More preferably, the halogen in the phenyl halide containing a substituted or unsubstituted C1 - C4 alkyl group is chlorine.

[0073] Copper ion salt:

[0074] In some embodiments, the copper ion salt of the present invention is not particularly limited, as long as the electroplating purpose can be achieved, such as an acidic copper salt.

[0075] Preferably, the copper ion salt is selected from one or a combination of copper sulfate, copper phosphide, copper phosphate, copper pyrophosphate, copper oxide, copper chloride, copper nitrate, copper sulfonate, copper acetate; more preferably, the copper ion salt is selected from one or a combination of copper sulfate, copper oxide, copper chloride.

[0076] Acidic electrolyte:

[0077] In some embodiments, the acidic electrolyte of the present invention is not particularly limited, and examples include sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, sulfonic acid, benzenesulfonic acid, glyoxylic acid, formic acid, acetic acid, etc.

[0078] Preferably, the acidic electrolyte is sulfuric acid and / or hydrochloric acid.

[0079] Brightener:

[0080] In some embodiments, the brightener of the present invention is not particularly limited, and examples include sodium dimethylthiocarbamoyl propane sulfonate, pyridinium propane sulfonate, sodium 2-formylbenzenesulfonate, sodium styrenesulfonate, sodium polydithiodipropane sulfonate, sodium thiazolinyl dithiopropane sulfonate, N,N-dimethyldithiocarboxamide propane sulfonate, sodium 3-mercaptopropane sulfonate, sodium 2,3-dimercaptopropane sulfonate, sodium 2-hydroxy-3-mercaptopropane sulfonate, sodium 3-(benzothiazol-2-ylthio)-propane sulfonate, phenyl dithiopropane sulfonate, sodium polydimethylamidosulfonate, sodium dimercaptopropanesulfonate, sodium 2-mercaptobenzimidazole-5-sulfonate, sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate, etc.

[0081] Preferably, the brightener is a compound of sodium 3-mercaptopropane sulfonate (MPS) and sodium polydithiodipropane sulfonate (SPS), and the mass ratio of the two is (0.01 - 0.5):1.

[0082] Inhibitor:

[0083] In some embodiments, the inhibitor of the present invention is not particularly limited, for example, one or a combination of polyethylene glycol, polypropylene alcohol, polyvinylpyrrolidone, glycerol polyoxypropylene ether, ethylene oxide-propylene oxide block polymer, polyethylene glycol-propylene oxide-ethylene oxide triblock copolymer.

[0084] Preferably, the molar mass of the inhibitor is 4000 - 40000 g / mol.

[0085] Preferably, the inhibitor is selected from one or more of PEG1500, PEG10000, and 50HB-400.

[0086] Among them, PEG1500 and PEG10000 are both polyethylene glycol (CAS No.: 25322-68-3), and 50HB-400 is poly(ethylene oxide)-poly(propylene oxide) monobutyl ether (CAS No.: 9038-95-3); these products can be commercially available, such as Dow Chemical.

[0087] Beneficial effects:

[0088] The present invention provides an X-type hole rapid filling electroplating process, device and electroplating solution, which have the following advantages:

[0089] (1) The present invention preferably uses the modified semi-additive process (mSAP) to fill the X-type holes by electroplating. The overall process flow does not involve excessive panel electroplating, and only the independent X-type holes can be filled. This not only shortens the process time but also obtains PCB parts with excellent quality, and the electroplating hole filling effect is good;

[0090] (2) The adapted orifice of the present invention has a maximum orifice diameter of 20 - 200 μm, a hole depth of 40 - 500 μm, and a thickness-to-diameter ratio of 0.5 - 5 for the X-shaped hole. For the X-shaped holes meeting these conditions, rapid filling can be achieved, with a filling speed of over 100 μm / min and good filling uniformity.

[0091] (3) The present invention develops and exposes the dry film on the surface of the printed circuit board through a film with an opening part, and sets the area of the opening part to be greater than or equal to the maximum orifice diameter of the X-shaped hole. During exposure and development, the X-shaped hole and the orifice edge are exposed, and the dry film part can still play a masking role for the conductive layer on the printed circuit board surface and the orifice edge of the X-shaped hole, optimizing the hole filling effect.

[0092] (4) The present invention adopts a specific electroplating solution to adapt to the optimized process flow. Especially, a specific leveling agent is introduced into the electroplating solution. A polymerization product is prepared by reacting N-methyl-2,2'-diaminodiethylamine with 1,6-hexanediol diglycidyl ether, which can optimize the electroplating hole filling effect. The depression of the electroplated coating is less than 10 μm, and there is no hollow in the hole, effectively improving the reliability and stability of the PCB board.

[0093] (5) The process method of the present invention is simple to operate and easy to realize automated production, meeting the requirements of mass production.

[0094] (6) The electroplating hole filling process of the present invention significantly saves costs, solves the problem of the need for copper thinning process due to the overly thick copper plating layer in the traditional copper plating process, and improves the overall production efficiency.

[0095] (7) The hole filling process of the present invention has strong adaptability, can be paired with various electroplating solutions for electroplating hole filling operations, and achieves excellent X-shaped hole filling effects, thus being widely used in the production lines of electroplated board factories.

[0096] (8) The present invention does not require electroplating thickening on the board surface, saving copper source materials and costs from the source, reducing steps such as copper thinning in the process design, simplifying the process flow and improving the yield of printed circuit boards. The process of the present invention is particularly applicable but not limited to the semi-additive process and the modified semi-additive process in the field of PCB electroplating, and has broad application prospects. Description of the Drawings

[0097] Figure 1 : Schematic cross-section of X-shaped hole filling; where H1 is the overall board thickness around the X-shaped hole after electroplating, H2 is the filling thickness inside the X-shaped hole after electroplating, H3 is the copper plating layer thickness (excluding the bottom copper), H4 is the electroplating hole depression value (dimple), H5 is the maximum orifice diameter of the X-shaped hole, H6 is the maximum diameter at the center of the X-shaped hole, and H7 is the thickness of the printed circuit board.

[0098] Figure 2: Schematic flow diagram of the rapid filling electroplating process for X-shaped holes of the present invention;

[0099] Figure 3 : Schematic structural diagram of a printed circuit board during the rapid filling process of X-shaped holes of the present invention; wherein Figure 3 a is the schematic structural diagram of the printed circuit board after the treatment of step S103, Figure 3 b is the schematic structural diagram of the printed circuit board after the treatment of step S202, Figure 3 c is the schematic structural diagram of the printed circuit board after the treatment of step S203, Figure 3 d is the schematic structural diagram of the printed circuit board after the treatment of step 302; Figure 3 Among them, 301 is the X-shaped hole, 302 is the conductive layer, 303 is the dry film, 304 is the edge part of the dry film, and 305 is the filled X-shaped hole;

[0100] Figure 4 : Structural framework diagram of the rapid filling electroplating device for X-shaped holes provided by the present invention (401 - setting unit, 402 - exposure and development unit, 403 - electroplating unit);

[0101] Figure 5 : Schematic flow diagram of processing methods for different PCB products (Line A is the subtractive process, Line B is the SAP process, and Line C is the mSAP process);

[0102] Figure 6 : Microsection diagram of the filled X-shaped holes on the printed circuit board actually produced in Example 1 of the present invention (the X-shaped hole specification on this printed circuit board is 60μmΦ×50μmt);

[0103] Figure 7 : Microsection diagram of the filled X-shaped holes on the printed circuit board actually produced in Example 2 of the present invention (the X-shaped hole specification on this printed circuit board is 80μmΦ×100μmt);

[0104] Figure 8 : Microsection diagram of the filled X-shaped holes on the printed circuit board actually produced in Example 3 of the present invention (the X-shaped hole specification on this printed circuit board is 100μmΦ×200μmt);

[0105] Figure 9 : Microsection diagram of the filled X-shaped holes on the printed circuit board actually produced in Example 4 of the present invention (the X-shaped hole specification on this printed circuit board is 100μmΦ×300μmt);

[0106] Figure 10 : Microsection diagram of the filled X-shaped holes on the printed circuit board actually produced in Comparative Example 1 of the present invention (the X-shaped hole specification on this printed circuit board is 100μmΦ×200μmt);

[0107] Figure 11 : Schematic diagram of the cross-section of the printed circuit board after filling the X-shaped holes in Comparative Example 2 of the present invention (the specifications of the X-shaped holes on the printed circuit board are 100μmΦ×200μmt);

[0108] Figure 12 : Schematic diagram of the cross-section of the printed circuit board after filling the X-shaped holes in Comparative Example 3 of the present invention (the specifications of the X-shaped holes on the printed circuit board are 100μmΦ×200μmt). Detailed implementation manners

[0109] The information of some raw materials involved in the following examples and comparative examples is as follows.

[0110] N-methyl-2,2'-diaminodiethylamine: CAS number is 4097-88-5, brand is Alfa Aesar, product number is Y31418;

[0111] 1,6-Hexanediol diglycidyl ether: CAS number is 16096-31-4, brand is Maya, product number is 27659;

[0112] 1,7-Heptanediamine: CAS number is 646-19-5, brand is Macklin, product number is D807446.

[0113] Neopentyl glycol diglycidyl ether: CAS number is 17557-23-2, brand is Sigma-Aldrich, product number is 338036.

[0114] Note: Unless otherwise specified, the solvent of the solutions involved in the present invention is water; the concentrations involved are all mass concentrations; the room temperature is 25°C; and, the present invention does not particularly limit the sources of the raw materials for preparing the electroplating solution, and the raw materials used are all commercially available. Those skilled in the art can select the commonly used analytical pure or superior grade materials on the market according to needs.

[0115] Examples

[0116] Example 1

[0117] In the first aspect of this example, a rapid filling electroplating process for X-shaped holes is provided (for the process schematic diagram, see Figure 2 , and for the structural schematic diagram of the printed circuit board during the manufacturing process, see Figure 3 ), and the operation steps include:

[0118] S1. Provide a printed circuit board;

[0119] S2. Set a dry film on the surface of the printed circuit board, and use a film to expose and develop the dry film;

[0120] S3. Electroplate and fill the holes;

[0121] The printed circuit board is provided with X-shaped holes. The depth of the X-shaped holes is 50 μm (the X-shaped holes in the present invention are through holes, and the hole depth is the board thickness), the maximum hole diameter at the hole opening is 60 μm, and the thickness-diameter ratio is 0.83.

[0122] In step S1, a conductive layer 302 is provided on both the board surface of the printed circuit board and the inside of the X-shaped holes. The conductive layer is a copper plating layer. That is, step S1 specifically includes:

[0123] S101. Drill the printed circuit board substrate (copper clad laminate) to form circuit holes (X-shaped holes 301);

[0124] S102. Perform electroless copper plating on the drilled copper clad laminate so that both the board surface and the holes of the copper clad laminate are plated with a copper plating layer (i.e., the conductive layer) with a thickness of 0.8 μm;

[0125] S103. Perform flash copper plating on the copper clad laminate to form a thin copper layer (2 μm) with fine copper layer crystals, and obtain the printed circuit board for standby.

[0126] In step S2, the film is provided with an opening part. The shape of the opening part is circular, and its diameter is 250 μm. Specifically, according to the X-shaped hole area on the printed circuit board, a pattern for opening the X-shaped holes is correspondingly set on the film, that is, an opening part for opening the X-shaped holes is formed.

[0127] Step S2 specifically includes:

[0128] S201. Stick a dry film 303 on the surface of the printed circuit board obtained in step S1, and then stick the film with the set opening part on the surface of the dry film;

[0129] S202. Perform exposure treatment on the printed circuit board through an exposure device so that the pattern on the dry film is transferred to the copper clad laminate;

[0130] S203. Use a developer to remove the uncured area.

[0131] In this embodiment, the circuit pattern is defined through the exposure and development steps of S202 and S203. After exposure and development, the dry film can expose the X-shaped holes and leave a copper ring with an appropriate size around the X-shaped holes (i.e., the edge part 304 of the dry film), which is convenient for masking the edge of the hole opening of the X-shaped holes during the subsequent hole filling, and improves the hole filling effect.

[0132] Step S3 specifically includes:

[0133] S301. Place the printed circuit board in an electroplating solution at 25.5 °C for pattern electroplating. During this process, segmented DC current is used for electroplating to fill the holes; the current density is 14 ASF, and the electroplating hole filling time is 50 min.

[0134] S302. Perform film stripping and flash etching operations on the electroplated printed circuit board to remove excess copper, retain the precise circuit pattern, complete the rapid filling of the X-shaped holes (i.e., 305), and obtain the printed circuit board product.

[0135] In the second aspect of this embodiment, an electroplating device for rapid filling of X-shaped holes is provided to implement the above-mentioned rapid filling electroplating process operation for X-shaped holes. The structural framework diagram is shown in Figure 4 , and the electroplating device includes:

[0136] A setting unit for setting a dry film on the surface of the printed circuit board provided with X-shaped holes;

[0137] An exposure and development unit for exposing and developing the dry film using a film;

[0138] An electroplating unit for electroplating and filling the X-shaped holes.

[0139] The electroplating method of the electroplating unit is a vertical electroplating method, specifically using a vertical gantry electroplating line with a 1600L line body. The anode of the electroplating unit uses a double-layer insoluble iridium-tantalum coated titanium mesh, and the cathode is the workpiece to be plated, that is, the printed circuit board.

[0140] In the third aspect of this embodiment, an electroplating solution is provided, and the electroplating solution is used in the electroplating and filling step of the above-mentioned rapid filling electroplating process for X-shaped holes; the formula of the electroplating solution is shown in Table 1.

[0141] Table 1

[0142]

[0143] The leveling agent used in Example 1 is specifically a polymerization product of N-methyl-2,2'-diaminodiethylamine and 1,6-hexanediol diglycidyl ether; the two are first mixed to undergo a chelation reaction to obtain a tertiary amine polymer, and then a quaternization reaction occurs in the presence of a halogenated hydrocarbon to obtain a quaternized copolymer. The specific preparation method includes:

[0144] At room temperature, 200 mmol of 1,6 - hexanediol diglycidyl ether was added to a three - necked round - bottom flask. Then, 100 mL of deionized water was added to the three - necked round - bottom flask, and nitrogen was filled for protection. The temperature was kept constant at 90 °C in a nitrogen environment, and 200 mmol of N - methyl - 2,2'-diaminodiethylamine was added dropwise under constant pressure (dropped evenly within 30 min). After dropping, the temperature was kept at 90 °C and the reaction continued for 12 hours. The reaction material changed from the initial white suspension to a brown - yellow liquid. The temperature was further increased to 100 °C, and then 50 mmol of benzyl chloride was added dropwise to the three - necked round - bottom flask under constant pressure (dropped within 8 min). It was heated at 100 °C for 10 hours, and then stirred at room temperature for 2 hours. Finally, an amber reaction product was obtained, and the reaction product was washed with a 0.5 wt% sulfuric acid aqueous solution and diluted to a pH of 1.5. The obtained reaction product solution could be used as a leveling agent without further purification.

[0145] Examples 2 - 4 and Comparative Examples 1 - 2

[0146] Examples 2 - 4 and Comparative Examples 1 - 2 provide an X - type hole rapid filling electroplating process, device and electroplating solution. The specific implementation is the same as that of Example 1; the differences are listed in Table 2.

[0147] Table 2

[0148]

[0149] Note: In Table 2, "-" represents not added; the pore diameter of the X - type hole refers to the maximum pore diameter at the hole opening, and the board thickness refers to the board thickness of the copper - clad laminate before electroplating.

[0150] The leveling agent 1 in Table 2 is the polymerization product of N - methyl - 2,2'-diaminodiethylamine and 1,6 - hexanediol diglycidyl ether; the leveling agent 2 is the polymerization product of 1,7 - heptanediamine and 1,6 - hexanediol diglycidyl ether; the leveling agent 3 is the polymerization product of N - methyl - 2,2'-diaminodiethylamine and neopentyl glycol diglycidyl ether. The preparation methods of the leveling agent 2 and the leveling agent 3 refer to the preparation method of the leveling agent 1 in Example 1.

[0151] Examples 1 - 4 used the same electroplating solution formula, and the difference lies in the specifications of the X - type holes (the thickness of the copper - clad laminate and the pore diameter of the X - type holes increased), so the electroplating time was adaptively extended.

[0152] Regarding Comparative Example 1, the electroplating process it adopted was different from that of Examples 1 - 4. Specifically, full - board electroplating was used, and there was no insulating layer such as dry film on the surface of the copper - clad laminate to block plating. Since the actual copper - plating area increased significantly, the current density was more dispersed, so the electroplating time was extended to 80 min.

[0153] Performance Test

[0154] Electroplating Results:

[0155] Samples of the printed circuit boards of the examples and comparative examples after filling the X-shaped holes were taken for observation to obtain sectional views ( Figures 6 to 12 ). Refer to Figure 1 for the schematic cross-sectional view of the X-shaped hole filling to clarify H1 to H7, and calculate the filling rate and depression degree of each sample. At the same time, observe whether there is a hollow after hole filling, and calculate the line arc rate according to the depression degree of the plating layer after hole filling. The test results of each item are recorded in Table 3.

[0156] Filling rate = (H2 / H1)×100%;

[0157] Depression degree = H4;

[0158] Line arc rate = (height at the center - height at the edge) / height at the edge×100%; where the height at the center is the height (H4) measured along the central axis of the line, and the height at the edge is the height (H3) measured along the edge of the fine line.

[0159] Table 3

[0160]

[0161] As shown in Table 3, the process provided by the present invention can achieve rapid filling of X-shaped holes. Compared with the traditional full-panel electroplating process, the electroplating hole filling process of Examples 1 to 4 can fill the X-shaped holes faster with a specific electroplating solution. The filling speed can reach more than 100 μm / min, and the filling uniformity is good. The depression degree of the X-shaped holes after electroplating is less than 10 μm. More importantly, there is no hollow in the holes after hole filling, effectively improving the reliability and stability of the PCB board. When the leveling agent in the process or electroplating solution was adjusted in Comparative Examples 1 to 3, the final electroplating hole filling effect would deteriorate to varying degrees and could not meet the requirements of production line parts. The electroplating effect obtained by the electroplating solution of the present invention is excellent and can match imported products (such as the electroplating solutions CU-BRITE VL, CU-BRITE VLX, CU-BRITE TF II, CU-BRITE TF5, CU-BRITE TF7, CU-BRITE TFL of JCU Corporation of Japan, or the electroplating solution EVF-15 of Rohm and Haas of the United States). At the same time, the hole filling process of the present invention has strong adaptability and can be used for electroplating hole filling operations with various electroplating solutions (such as those listed above) to obtain excellent X-shaped hole filling effects, thus being widely used in the production lines of electroplated board factories.

Claims

1. An X-shaped hole rapid filling electroplating process, characterized in that: The steps include: S1. Provide printed circuit boards; S2. Disposing a dry film on the surface of the printed circuit board and exposing and developing the dry film using a film; S3. Electroplating and hole filling; The printed circuit board is provided with an X-shaped hole; The board surface of the printed circuit board and the interior of the X-shaped hole are both provided with a conductive layer; The film is provided with a window portion, and the area of ​​the window portion is greater than or equal to the maximum aperture of the X-shaped hole.

2. The X-shaped hole rapid filling electroplating process according to claim 1, characterized in that: The X-shaped hole has a hole depth of 40-500 μm, a maximum hole diameter of 20-200 μm, and a thickness-to-diameter ratio of 0.5-5.

3. The X-shaped hole rapid filling electroplating process according to claim 2, characterized in that: The time for the electroplating hole filling is 40 to 240 minutes, preferably 50 to 80 minutes.

4. The X-shaped hole rapid filling electroplating process according to claim 1, characterized in that: The S1 step specifically includes: S101. Drilling a printed circuit board substrate to form an X-shaped hole; S102. Chemical copper plating is performed on the printed circuit board substrate after drilling, so that the surface of the printed circuit board substrate and the X-shaped hole are plated with a copper layer; S103. Perform a flash copper plating operation on the printed circuit board substrate to form a thin copper layer to obtain a printed circuit board for standby use.

5. The X-shaped hole rapid filling electroplating process according to claim 4, characterized in that: The concavity of the plating layer after the hole filling by electroplating in step S3 is less than 10 μm.

6. An X-shaped hole rapid filling electroplating device, characterized in that: The electroplating device comprises: A setting unit, used for setting a dry film on the surface of a printed circuit board provided with an X-shaped hole; An exposure and development unit, used for exposing and developing the dry film using a film; The electroplating unit is used to fill the X-shaped holes with electroplating; The electroplating device is used to implement the X-shaped hole rapid filling electroplating process as described in any one of claims 1 to 5.

7. An electroplating solution, the electroplating solution is used in the electroplating and hole filling step of the X-shaped hole rapid filling electroplating process according to any one of claims 1 to 5 or the electroplating unit of the X-shaped hole rapid filling electroplating device according to claim 6, characterized in that: The raw materials for preparing the electroplating solution include: 30-100 mg / L of chloride ions, 20-120 g / L of acidic electrolyte, 150-260 g / L of copper ion salt, 0.5-6 mg / L of brightener, 10-50000 mg / L of inhibitor, 10-10000 mg / L of leveler and solvent; the solvent is deionized water; The leveling agent is a nitrogen-containing organic compound, which is a product of polymerization of aliphatic amine compounds and polyol glycidyl ether.

8. The electroplating solution according to claim 7, characterized in that The aliphatic amine compound is an aliphatic primary diamine compound, and the aliphatic primary diamine compound includes one or more combinations of ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, adipic acid diamine, 2-methyl-1,3-propylenediamine, N-methyl-2,2'-diaminodiethylamine, N-ethyl-1,3-propylenediamine, N-propyl-1,3-propylenediamine, and N-acetyl-1,3-propylenediamine; Preferably, the aliphatic primary diamine compound is N-methyl-2,2'-diaminodiethylamine.

9. The electroplating solution according to claim 8, characterized in that The polyol glycidyl ether compound is a diol diglycidyl ether, and the diol diglycidyl ether includes a combination of one or more of 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-cyclohexanedimethanol glycidyl ether, bisphenol A-diglycidyl ether, tetrahydrophthalic acid diglycidyl ether, 1,5-pentanedithiol glycidyl ether, and 1,2-cyclohexanediol diglycidyl ether; Preferably, the diol diglycidyl ether is 1,6-hexanediol diglycidyl ether.

10. The electroplating solution according to claim 9, characterized in that The molar ratio of the aliphatic primary diamine compound to the diol diglycidyl ether is 0.25:(0.8-1).

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