A method for preparing a conductive layer on a surface of a non-conductive substrate and applications thereof

Abstract

The present application relates to the technical field of hole metallization, and particularly relates to a method for preparing a conductive layer on the surface of a non-conductive substrate and application thereof. The method comprises the following steps: preparing a part containing a copper layer and a non-conductive substrate layer, and performing surface charge adjustment treatment on the non-conductive substrate layer; immersing the part into a carbon liquid tank for adsorption treatment to form a thin carbon layer; immersing the part into a carbon fixing tank for fixing treatment to form a carbon-based conductive layer; and performing micro-etching treatment on the carbon-based conductive layer to remove the carbon-based conductive layer on the surface of the copper layer, thereby obtaining a plated product. The method provided in the present application can adsorb carbon material on the surface of a non-conductive substrate layer such as a printed circuit board, an IC carrier board and a substrate to form a conductive film layer, which serves as a conductive base for subsequent electroplating. The method has excellent conductive performance, and the carbon material film layer is extremely thin, thereby meeting the needs of metallization conduction in various fields.

Description

Technical Field

[0001] This invention relates to the field of hole metallization technology, and in particular to a method for preparing a conductive layer on the surface of a non-conductive substrate and its application. Background Technology

[0002] Hole metallization is a key process in the manufacturing of electronic components such as PCBs (Printed Circuit Boards) and ICs (Integrated Circuit Boards). Its core purpose is to achieve electrical conductivity in non-conductive substrate areas (such as fiberglass or resin in the hole walls), providing a foundation for subsequent electroplating of metal layers. Carbon via technology, as an important alternative to hole metallization, has significant advantages over traditional chemical copper plating processes. Its typical process flow includes desmearing, neutralization, hole preparation, carbonization, pickling, drying, hole preparation, carbonization, micro-etching, and drying. The entire process is time-efficient, does not contain toxic volatile chemicals such as formaldehyde, and does not require the use of precious metal palladium as a copper plating catalyst. It is environmentally friendly, has a simplified process, and is cost-controllable, making it a key new process promoted in the industry. Existing carbon via processes mainly involve preparing conductive materials such as nano-graphite and conductive carbon black into dispersions, allowing conductive particles to adsorb onto the fiberglass and substrate surfaces of the PCB hole walls, forming a uniform and dense conductive layer to meet the basic metallization conductivity requirements.

[0003] However, traditional carbon via processes often use graphite particles or carbon black as the sole conductive matrix (e.g., US Patent 5389270, US Patent 5690805). While these methods achieve a certain level of conductivity, they have significant limitations in practical applications: when conductive particles adsorb onto non-conductive substrates (especially circuit board hole walls), they tend to form an excessively thick adsorption layer, making it difficult to completely remove excess carbon and posing a risk of residue. Simultaneously, an excessively thick carbon layer reduces the bonding strength between the subsequent electroplated metal layer and the carbon layer, easily leading to plating peeling and consequently affecting the heat dissipation performance of electronic components. These issues are particularly prominent in high-end HDI (High-Density Interconnect) boards, IC substrates, and other applications with stringent performance requirements—these products demand crack-free conductive layers and seamless hole wall bonding to ensure stable heat dissipation and conductivity. Traditional carbon via processes are no longer sufficient to meet the demands of these high-end applications. Existing technologies attempt to prepare conductive layers using composite carbon materials (e.g., Chinese invention patent application CN115397109A, Chinese invention patent CN115594171B), but such solutions still have significant technical drawbacks: First, the thickness of the conductive film layer prepared by these solutions is always difficult to achieve ultra-thinness, failing to meet the ultra-thin standards required for high-end applications; second, such solutions generally suffer from complex formulations and cumbersome preparation operations, making it difficult to achieve efficient and stable large-scale production.

[0004] Against this backdrop, there is an urgent need to provide a technical solution that is easy to operate, highly feasible, and capable of stably preparing ultra-thin conductive films while balancing conductivity and adhesion, in order to overcome the bottlenecks of existing technologies and meet the application needs of high-end electronic devices. Summary of the Invention

[0005] The first aspect of the present invention provides a method for preparing a conductive layer on the surface of a non-conductive substrate, the method comprising the following steps: Prepare components containing copper layers and non-conductive substrate layers, and perform surface charge adjustment treatment on the non-conductive substrate layers; The component is immersed in a carbon bath for adsorption treatment to form a thin carbon layer; The component is immersed in a carbon bath for fixation to form a carbon-based conductive layer. The carbon-based conductive layer is micro-etched to remove the carbon-based conductive layer from the surface of the copper layer, resulting in the finished plated part.

[0006] To address the problems in existing carbon pore processes, such as excessively thick carbon layers leading to high residual risks, weak bonding strength between electroplated metal layers and carbon layers (easily peeled off), and difficulty in meeting the requirements of "crack-free, peel-free, and high heat dissipation" in high-end HDI and IC substrate fields, this invention adopts a core process scheme of surface charge adjustment, carbon liquid adsorption to form a thin carbon layer, fixed carbon tank, and micro-etching treatment. This achieves technical effects such as uniform and ultra-thin carbon film (124-168nm), excellent DTV conductivity, no peeling of the coating, and good electrical conductivity. The reasons are as follows: the surface charge adjustment step optimizes the surface charge of the non-conductive substrate layer, laying the foundation for uniform carbon liquid adsorption and avoiding excessive local carbon layer accumulation; a thin carbon layer is first prepared in the carbon liquid bath to ensure uniform wetting of the carbon layer on the hole wall and controllable thickness, reducing the risk of residue; further, the fixation treatment of the fixed carbon bath enhances the bonding force between the carbon layer and the substrate, and the micro-etching treatment further removes excess carbon layer on the copper layer surface, avoiding carbon layer residue from affecting the bonding strength between the electroplated metal layer and the substrate; finally, the carbon layer is thin and uniform, with strong bonding force and stable conductivity, meeting the requirements of high-end hole metallization.

[0007] It should be noted that "hole metallization" is a common term in the PCB industry. Its core meaning is "to make insulating holes conductive in order to achieve interlayer electrical connections," and it does not specifically mean that "the hole walls must be metal." Although carbon via technology uses a carbon layer to replace the traditional chemical copper layer, the ultimate goal is still to provide a base for subsequent electroplating of metallic copper. Therefore, the industry still commonly categorizes it under "hole metallization."

[0008] In some implementations, the method specifically includes the following steps: S1. Clean the components containing copper layers and non-conductive substrate layers, and simultaneously perform surface charge adjustment treatment on the non-conductive substrate layers; S2. Immerse the component in a carbon bath for adsorption treatment to form a thin carbon layer on the surface of the non-conductive substrate layer; S3. Dry the thin carbon layer; S4. The component is immersed in a carbon bath for fixation to form a carbon-based conductive layer; S5. Perform micro-etching on the carbon-based conductive layer to remove the carbon-based conductive layer from the surface of the copper layer; S6. Dry the component to obtain the plated finished product; a conductive layer is formed on the surface of the non-conductive substrate layer of the obtained plated finished product.

[0009] In some embodiments, the component described in this invention is a carrier board component that simultaneously has a copper layer and a non-conductive substrate layer, such as a PCB (printed circuit board) board or an IC (integrated circuit board) carrier board.

[0010] In some embodiments, the preparation steps include cleaning the component containing the non-conductive substrate layer to remove surface contaminants.

[0011] Optionally, in step S1, a charge-adjusting liquid is used for cleaning and surface charge adjustment.

[0012] The raw materials for preparing the charge-adjusting liquid, by mass percentage, include: Alkylamine compounds 2-7%, halogenated amines 2-10%, polyquaternium salts 1-20%, water to make up the balance.

[0013] Further options include 3% alkanolamine compounds, 5% haloamines, 6% polyquaternium salts, and water to make up the balance.

[0014] The alkanolamine compounds may include monoethanolamine, triethanolamine, diisopropanolamine, methyldiethanolamine, etc., and may further be selected as diethanolamine.

[0015] The ammonium halide may include tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium chloride, tetrapropylammonium bromide, etc.; it may also be tetramethylammonium chloride or tetramethylammonium bromide.

[0016] Optionally, the polyquaternium salt includes polyquaternium salt-2 and polyquaternium salt-32, and the mass ratio of polyquaternium salt-2 to polyquaternium salt-32 is (2-10):(1-5).

[0017] Optionally, the charge adjustment liquid in step S1 can be used by immersion or spraying; further, it can be used by immersion and spraying simultaneously.

[0018] Optionally, the temperature for cleaning and surface charge adjustment in step S1 is 40-60℃; examples include 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, etc.

[0019] Optionally, the cleaning and surface charge adjustment treatment time in step S1 is 0.25-60 min; further optionally, it is 0.5-20 min; examples include 0.5 min, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, etc.

[0020] Optionally, the components of the liquid in the carbon bath, by weight percentage, include: 0.1-4% carbon material, 0.5-2% alkaline compound, 0.1-5% surfactant, 0.1-2% dispersant, and solvent to make up the balance.

[0021] Further options include 1.25% carbon material, 1% alkaline compound, 0.5% surfactant, 1% dispersant, and solvent to make up the balance.

[0022] Optionally, the temperature of the adsorption treatment is 20-40℃; examples include 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃, 35℃, 36℃, 37℃, 38℃, 39℃, 40℃, etc.

[0023] Optionally, the adsorption treatment time is 0.2-60 min; more preferably 0.3-10 min; examples include 0.3 min, 0.5 min, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, etc.

[0024] Optionally, the carbon material includes conductive carbon black, graphene oxide, and nanographite; the mass ratio of conductive carbon black, graphene oxide, and nanographite is (0-2):(0.1-2):(0-1), and is not 0; further optionally, it is 0.2:1:0.05.

[0025] Optionally, the alkaline compound includes sodium carbonate and sodium bicarbonate, with a mass ratio of sodium carbonate to sodium bicarbonate of (0.01-1):1; more preferably, it is 0.05:1; the alkaline compound controls the pH of the solution in the carbon bath to be 8-10.

[0026] The surfactants mentioned may include nonylphenol polyoxyethylene ether, polyethylene glycol, octylphenol polyoxyethylene ether, polyethylene glycol octylphenyl ether, sodium dodecylbenzenesulfonate, etc.

[0027] Optionally, the surfactant includes nonylphenol polyoxyethylene ether and polyethylene glycol, wherein the mass ratio of nonylphenol polyoxyethylene ether to polyethylene glycol is (0.8-2):1, and more preferably 1:1.

[0028] Optionally, the weight-average molecular weight of the polyethylene glycol is 1000-8000; more preferably 2000.

[0029] The dispersants may include sodium naphthalene sulfonate, NNO (sodium methylene dinaphthalene sulfonate), polyacrylic acid, sodium carboxymethyl cellulose, etc.

[0030] Optionally, the dispersant comprises sodium naphthalenesulfonate and NNO, wherein the mass ratio of sodium naphthalenesulfonate to NNO is (0.2-1):(0.2-2).

[0031] The solvent is not particularly limited, as long as it can dissolve the solute in the bath solution, such as water.

[0032] Optionally, the components of the solution in the carbon fixation tank include: acid, buffer, stabilizer adsorbent and solvent II; the mass of the acid, buffer, and stabilizer adsorbent accounts for 5-30 wt% of the mass of the solution in the carbon fixation tank; further optionally, it is 15 wt%.

[0033] The acid can be listed as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc.; sulfuric acid can be selected as an option.

[0034] The buffer may include acetate, citrate, tartrate, etc.; sodium acetate may be selected as an option.

[0035] The stabilizer adsorbent may include potassium iodide, tetramethylammonium iodide, ammonium iodide, sodium iodide, etc., and potassium iodide may be selected.

[0036] The mass ratio of the acid, buffer, and stabilized adsorbent is (0.1-2):(0.5-4):0.2-3); it can also be further selected as 1:2:1.5.

[0037] The solvent 2 is not particularly limited, as long as it can dissolve the solute in the bath solution, such as water.

[0038] Optionally, the temperature for the fixation treatment is 55-90℃; examples include 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, and 90℃.

[0039] Optionally, the fixed processing time is 0.5-30 min; examples include 0.5 min, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, etc.

[0040] In some embodiments, the components are first immersed in water to clean them before being immersed in the carbon bath or carbon settling bath to remove surface residue.

[0041] Optionally, in step S5, a micro-etching solution is used to micro-etch the carbon-based conductive layer.

[0042] Optionally, the raw materials for preparing the micro-etching solution, by weight ratio, include: 4-12% sulfuric acid, 1-8% oxidant, 0.1-1% stabilizer, and the balance of solvent three; further optionally, it includes 5-10% sulfuric acid, 2-7.5% oxidant, 0.2-0.8% stabilizer, and the balance of solvent three.

[0043] The oxidizing agent can be listed as hydrogen peroxide, sodium persulfate, ammonium persulfate, etc.; hydrogen peroxide or sodium persulfate can be selected.

[0044] The stabilizer may include thiourea, aminotrimethylphosphonic acid, iminodisuccinic acid, disodium ethylenediaminetetraacetate, etc.; thiourea and aminotrimethylphosphonic acid may be selected; further optionally, the mass ratio of thiourea and aminotrimethylphosphonic acid is 1:(0.5-2); most preferably, it is 1:1.

[0045] Optionally, the amount of stabilizer added to the micro-etching solution is 0.2-0.5%.

[0046] The solvent is not specifically limited to any particular solvent, as long as it can dissolve the solute in the micro-etching solution; water is an example of such solvent.

[0047] Optionally, the temperature of the micro-etching treatment is 20-30℃, and can be listed as 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, etc.

[0048] Optionally, the micro-etching process can be performed for 10-120 seconds, such as 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds, 110 seconds, 120 seconds, etc.

[0049] To address the problems of excessively thick carbon layers, poor hole-climbing effects, and easy peeling of coatings in existing carbon pore processes, this invention employs a specific process scheme involving cleaning and adjustment, carbon liquid adsorption, carbon fixation treatment, and micro-etching. This achieves ultra-thin and uniform carbon films (124-168nm), continuous conductivity of 8 pores in the high ASF region, and no coating peeling. By precisely controlling the temperature and time of the cleaning and adjustment process, as well as the carbon liquid bath and carbon fixation bath treatments, the interface state of the cleaning and adjustment process is used as a basis for controlling the film thickness in conjunction with carbon liquid adsorption. Furthermore, the effects of carbon fixation treatment and micro-etching complement each other, fundamentally solving the defect of traditional methods in failing to produce extremely thin conductive layers. This achieves simultaneous attainment of the "thin, uniform, and strong" carbon layer and conductivity performance.

[0050] Optionally, the thickness of the conductive layer is ≤200nm; more preferably, the thickness of the conductive layer is 124-168nm.

[0051] The conductive layer of the present invention corresponds to an ultrathin conductive carbon layer formed by uniformly adsorbing specific carbon components onto the surface of a substrate and then undergoing carbon fixation and micro-etching treatments.

[0052] A second aspect of the present invention provides an application of the method described above for preparing a conductive layer on the surface of a non-conductive substrate, the method being applied to the hole metallization process of PCB, HDI or IC carrier boards.

[0053] Beneficial effects: This invention provides a method for preparing a conductive layer on the surface of a non-conductive substrate and its application, which has the following advantages: (1) The non-conductive substrate surface conductive layer preparation scheme provided by the present invention adopts the core process scheme of surface charge adjustment, carbon liquid adsorption to form a thin carbon layer, fixed carbon tank and micro-etching treatment, which can form a uniformly distributed ultra-thin carbon film on the hole wall, effectively improving the poor bonding problem during subsequent copper layer plating. (2) The method of the present invention achieves a conductive layer thickness as low as 200nm by precisely controlling the temperature and time of cleaning adjustment and carbon bath and fixed carbon bath treatment, and has low resistivity and excellent conductivity, which can support high-quality electroplating process. (3) In this invention, graphene oxide is introduced into the carbon liquid tank. By optimizing the ratio of conductive carbon black, graphene oxide and nano-graphite, as well as the selection of surfactants, stabilizers and other additives, the graphene oxide is fully dispersed and dissolved in the carbon liquid tank, which significantly improves the dispersion and wetting effect of the carbon liquid on the pore wall of the non-conductive substrate and ensures the stable adsorption of the conductive layer on the pore wall. (4) The solution of the present invention also has outstanding operability, the process flow is simplified and the parameters are easy to control. It does not require complex formula components and cumbersome operations, and can achieve efficient and stable large-scale production to meet the mass production requirements of high-quality plated parts. Attached Figure Description

[0054] Figure 1 Microscopic images of the conductive layer obtained in Example 1; Figure 2 Microscopic images of the conductive layer prepared in Comparative Example 5; Figure 3 Example 1: DTV electroplating effect diagram of the plated part; Figure 4 Comparative Example 7: DTV electroplating effect diagram of the plated parts; Figure 5 Comparative Example 7: Physical image of the plated part (before DTV electroplating). Detailed Implementation

[0055] The reagent and raw material information involved in the following examples is as follows.

[0056] Charge conditioning solution (prepared in 1L): by mass percentage, it includes 3% diethanolamine, 5% tetramethylammonium chloride, 3% polyquaternium-2, 3% polyquaternium-32, and water to make up the balance.

[0057] Polyquaternium-2 is from McLean, product number P871975.

[0058] Polyquaternium-32 is from Adamas, product number 016799908.

[0059] Carbon bath preparation (1L): Mix 1g of alkaline compound (0.05g sodium carbonate, 0.95g sodium bicarbonate), 0.5g of surfactant (0.25g nonylphenol polyoxyethylene ether, 0.25g polyethylene glycol), 1g of dispersant (0.5g sodium naphthalenesulfonate, 0.5g NNO), and 1.25g of carbon component (0.2g conductive carbon black, 1g graphene oxide, 0.05g nano-graphite), and dilute to 1L with water. Sonicate for 0.5h. The preparation temperature is controlled at room temperature and maintained as the working temperature. The polyethylene glycol has a weight-average molecular weight of 1000 and is from McLean Corporation, model number P815605.

[0060] The conductive carbon black has an average particle size of 30 nm and is from Cabot Corporation, model VXC-72.

[0061] The nano-graphite comes from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., model number 101384.

[0062] Graphene oxide comes from Hangzhou Gaoxi Technology Co., Ltd.

[0063] Preparation of the solution in the carbon fixation tank (1L): Add 500ml of water to a 1L carbon fixation tank, then slowly add 33g of sulfuric acid, 66g of sodium acetate, and 50g of potassium iodide, stir until dissolved, and then add water to bring the volume to 1L.

[0064] Micro-etching solution (1L preparation): Dissolve 80g of oxidant (sodium persulfate) and 4g of stabilizer (thiourea and aminotrimethylphosphonic acid) in a 5wt% sulfuric acid aqueous solution to prepare 1L of micro-etching solution.

[0065] Unless otherwise specified, the solvents used in the solutions involved in this invention are all water; the concentrations involved are all mass concentrations; the room temperature is 25°C; and the raw materials, equipment and other consumables used are all commercially available.

[0066] Example 1 This embodiment provides a method for preparing a conductive layer on the surface of a non-conductive substrate, including the following steps: S1. Cleaning and Adjustment: The components (PCB board) containing copper layers and non-conductive substrate layers are cleaned using a charge adjustment solution, while the surface charge of the non-conductive substrate layers is adjusted simultaneously. The charge adjustment solution is used by immersion and spraying at the same time. The treatment temperature is 50°C and the treatment time is 5 minutes. S2. Carbon liquid treatment: After immersing the component in water for cleaning, it is then immersed in a carbon liquid bath for adsorption treatment, so that a thin carbon layer is formed on the surface of the non-conductive substrate layer; the adsorption treatment temperature is room temperature and the treatment time is 5 minutes. S3. Dry the thin carbon layer with hot air (70±10℃); S4. Fixing: After cleaning the component by immersing it in water, it is then immersed in a carbon fixation tank for fixation treatment to form a carbon-based conductive layer; the fixation treatment temperature is 60℃ and the treatment time is 5min; S5. Micro-etching: The carbon-based conductive layer is micro-etched using a micro-etching solution to remove the carbon-based conductive layer from the surface of the copper layer; the micro-etching treatment is performed at room temperature for 1 minute. S6. Dry the component to obtain the plated finished product; a conductive layer is formed on the surface of the non-conductive substrate layer of the obtained plated finished product.

[0067] Examples 2-6 Examples 2-6 provide a method for preparing a conductive layer on the surface of a non-conductive substrate, with the specific implementation method being the same as in Example 1; the difference lies in the processing temperature of steps S1 or S4 in the process; see Table 1 for details.

[0068] Table 1

[0069] In Table 1, rt represents room temperature.

[0070] Examples 7-20 Examples 7-20 provide a method for preparing a conductive layer on the surface of a non-conductive substrate, with the specific implementation method being the same as in Example 2; the difference lies in the processing time of steps S1, S2, or S4 in the process being different; see Table 2 for details.

[0071] Table 2

[0072] Comparative Examples 1-3 Comparative Examples 1-3 provide a method for preparing a conductive layer on the surface of a non-conductive substrate, with the specific implementation method being the same as in Example 1; the difference lies in the processing temperature of steps S1 or S4 in the process; see Table 3 for details.

[0073] Table 3

[0074] In Table 3, rt represents room temperature.

[0075] Comparative Examples 4-7 Comparative Examples 4-7 provide a method for preparing a conductive layer on the surface of a non-conductive substrate, with the same specific implementation as Example 2; the difference lies in the processing time of steps S1, S2, or S4 in the process; see Table 4 for details.

[0076] Table 4

[0077] Performance testing The plated parts obtained from the examples and comparative examples were tested as follows; the test results are shown in Table 5.

[0078] 1. Conductive layer thickness After slicing the samples, the thickness of the conductive layer was observed and measured using a scanning electron microscope (SEM). Test data for each embodiment and comparative example are shown in Table 5. Microscopic images of the conductive layer in Example 1 and Comparative Example 5 are shown in... Figure 1 and Figure 2 .

[0079] For reference, the film thickness level of the technology in CN115397109A is above 0.2μm; the thickness of the conductive layer in this invention is significantly reduced.

[0080] 2. DTV (Diameter Through-Video Continuity Verification) Test Conductivity testing is performed using DTV-Chain / Hull-panel (a dedicated test carrier for verifying the quality of PCB through-hole plating). The baseline requirements are: the number of effective vias in the 25ASF area must not be less than 6, and the number of effective vias in the 10ASF area must not be less than 5.

[0081] Test conditions: substrate thickness 0.3mm, hole depth 1.2mm; electroplating method, current 1A, electroplating time 10min.

[0082] Acceptance criteria: 5 effective pores in high ASF area (25 ASF) and 3 effective pores in low ASF area (10 ASF).

[0083] Testing tool: Hull slot.

[0084] The number of holes in the high-area DTV of each embodiment and comparative example is shown in Table 5. The DTV electroplating effect diagrams of Embodiment 1 and Comparative Example 7 are shown in Table 5. Figure 3 and Figure 4 .

[0085] 3. Resistance The surface resistance and pore chain resistance of the samples were measured using a multimeter and a four-probe tester.

[0086] 4. Peel test The crack resistance of the electroplated coating was evaluated by thermal shock testing. The test conditions were: temperature 288℃, single impact duration 10s, and 6 cycles of impact. The test procedure followed the industry standard IPC-TM-650-2.6.8 "Determination of Thermal Stress, Plated-Through Holes".

[0087] After peel testing of each sample, the percentage of cracked coating on the hole slices was observed and counted.

[0088] Table 5

[0089] Table 5 and Figure 1-5The test results show that the conductive layer thickness obtained in Examples 1-20 is 124-168 nm, and the film is relatively thin overall. Under these conditions, DTV tests show excellent conductivity, and continuous conduction of all 8 pores is achieved in the high current density region (25 ASF). The sheet resistance of the film is 8-45 kΩ / □, and the pore chain resistance is 167–365 kΩ. Peel tests after electroplating show no peeling of the plating. It should be noted that the conductive layer prepared in this invention has reached an extremely thin level, even exceeding the detection limit of conventional characterization methods, making it difficult to observe clearly directly; for example… Figure 1 The 139nm thick conductive layer shown is actually the result obtained by tilting the sample at a specific angle; the actual thickness of the conductive layer is even thinner. It should be noted that Example 5 and Example 2 are samples from different batches with the same design, and their data fluctuations are within a reasonable range.

[0090] The test results of Comparative Examples 1 and 2 show that excessively high or low cleaning adjustment temperatures significantly weaken the film adhesion, leading to a risk of copper layer peeling. In Comparative Example 3, when the temperature of the carbon bath was set too low, not only was the via climbing effect poor, but copper layer peeling also occurred; all of these results failed to meet the usage requirements. The test results of Comparative Examples 4 and 5 show that if the cleaning and adjustment treatment time is too short, it will lead to uneven adsorption, resulting in a weak DTV hole climbing effect, with only 6 holes being able to conduct, and there is also a risk of coating peeling; while if the treatment time is too long, it will cause excessive adsorption. Although the conductivity is good, the film thickness will increase significantly (up to 331nm), which will also cause the risk of coating peeling.

[0091] The test results of Comparative Examples 6 and 7 show that if the carbon bath treatment time is too short, the carbon layer will have insufficient conductivity, and only 3 holes in the DTV can achieve conductivity. If the treatment time is too long, it will cause uneven thinning of the film layer, and prolonged immersion will also cause the carbon layer to loosen, making it impossible to form a uniform conductive layer (see...). Figure 5 Not only is the hole-crawling effect poor, but it can also cause copper plating peeling problems in subsequent processes.

[0092] The embodiments and descriptions above are merely illustrative of the principles and specific implementations of the present invention. Various changes and modifications may be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method for preparing a conductive layer on the surface of a non-conductive substrate, characterized in that, The method includes the following steps: Prepare components containing copper layers and non-conductive substrate layers, and perform surface charge adjustment treatment on the non-conductive substrate layers; The component is immersed in a carbon bath for adsorption treatment to form a thin carbon layer; The component is immersed in a carbon bath for fixation to form a carbon-based conductive layer. The carbon-based conductive layer is micro-etched to remove the carbon-based conductive layer from the surface of the copper layer, resulting in the finished plated part.

2. The method for preparing a conductive layer on the surface of a non-conductive substrate according to claim 1, characterized in that, The method includes the following steps: S1. Clean the components containing copper layers and non-conductive substrate layers, and simultaneously perform surface charge adjustment treatment on the non-conductive substrate layers; S2. Immerse the component in a carbon bath for adsorption treatment to form a thin carbon layer on the surface of the non-conductive substrate layer; S3. Dry the thin carbon layer; S4. The component is immersed in a carbon bath for fixation to form a carbon-based conductive layer; S5. Perform micro-etching on the carbon-based conductive layer to remove the carbon-based conductive layer from the surface of the copper layer; S6. Dry the component to obtain the plated finished product; a conductive layer is formed on the surface of the non-conductive substrate layer of the obtained plated finished product.

3. The method for preparing a conductive layer on the surface of a non-conductive substrate according to claim 2, characterized in that, In step S1, a charge-adjusting solution is used for cleaning and surface charge adjustment. The raw materials for preparing the charge-adjusting liquid, by mass percentage, include: Alkylamine compounds 2-7%, halogenated amines 2-10%, polyquaternium salts 1-20%, water to make up the balance.

4. The method for preparing a conductive layer on the surface of a non-conductive substrate according to claim 2, characterized in that, In step S1, the charge adjustment liquid is used by soaking or spraying. Preferably, the charge adjustment liquid in step S1 is used by immersion and spraying simultaneously.

5. The method for preparing a conductive layer on the surface of a non-conductive substrate according to claim 3, characterized in that, The temperature for cleaning and surface charge adjustment in step S1 is 40-60℃, and the processing time is 0.25-60 min.

6. The method for preparing a conductive layer on the surface of a non-conductive substrate according to claim 1, characterized in that, The components of the liquid in the carbon bath, by weight percentage, include: 0.1-4% carbon material, 0.5-2% alkaline compound, 0.1-5% surfactant, 0.1-2% dispersant, and solvent to make up the balance. The carbon material includes conductive carbon black, graphene oxide, and nanographite; the mass ratio of conductive carbon black, graphene oxide, and nanographite is (0-2):(0.1-2):(0-1), and is not 0; Preferably, the alkaline compound comprises sodium carbonate and sodium bicarbonate, wherein the mass ratio of sodium carbonate to sodium bicarbonate is (0.01-1):1; Preferably, the surfactant comprises nonylphenol polyoxyethylene ether and polyethylene glycol, wherein the mass ratio of nonylphenol polyoxyethylene ether to polyethylene glycol is (0.8-2):1; Preferably, the dispersant comprises sodium naphthalenesulfonate and NNO, wherein the mass ratio of sodium naphthalenesulfonate to NNO is (0.2-1):(0.2-2).

7. The method for preparing a conductive layer on the surface of a non-conductive substrate according to claim 1, characterized in that, The fixation treatment temperature is 55-90℃, and the fixation treatment time is 0.5-30min.

8. The method for preparing a conductive layer on the surface of a non-conductive substrate according to claim 1, characterized in that, The components of the solution in the carbon fixation tank include: acid, buffer, stabilizer adsorbent and solvent II; the mass of the acid, buffer and stabilizer adsorbent accounts for 5-30 wt% of the total mass of the solution in the carbon fixation tank.

9. The method for preparing a conductive layer on the surface of a non-conductive substrate according to claim 2, characterized in that, In step S5, the carbon-based conductive layer is micro-etched using a micro-etching solution. The temperature for the micro-etching treatment is 20-30℃, and the treatment time is 10-120s; Preferably, the raw materials for preparing the micro-etching solution, by weight ratio, include: 4-12% sulfuric acid, 1-8% oxidant, 0.1-1% stabilizer, and solvent (balanced by supplementation).

10. An application of the method for preparing a conductive layer on the surface of a non-conductive substrate according to claims 1-9, characterized in that, The method is applied to the hole metallization process of PCB, HDI or IC substrates.

Images