Through hole filling electroplating method and system for printed circuit board

Abstract

The invention relates to the field of integrated circuit manufacturing, in particular to the technical field of manufacturing of semiconductor device special equipment such as a photoetching machine and an etching machine special for production, and provides a through hole filling electroplating method and system for a printed circuit board. The method comprises the following steps: carrying out laser micro-through-hole processing on the printed circuit board; carrying out glue removal treatment on the printed circuit board with the micro through hole; carrying out black hole treatment or direct electroplating treatment on the degummed printed circuit board; performing porefilling electroplating on the treated printed circuit board by using an acidic copper plating porefilling special liquid medicine; in the hole filling electroplating process, a multi-stage electroplating current parameter program is adopted, in-hole pre-plating is carried out at low current density in the initial stage, it is ensured that hole walls are evenly covered, after the main hole filling stage is started, pulse or periodic reverse current is adopted, the current density is increased in a stepped mode, and through holes are filled with acid copper plating hole filling special liquid medicine; and parameters are adjusted at the last stage of filling to ensure that the copper thickness of the hole surface is uniform, and dished pits or excessive recesses are avoided.

Description

Technical Field

[0001] This application relates to the field of integrated circuit manufacturing, particularly to the field of manufacturing technology for special equipment for semiconductor devices such as dedicated lithography machines and etching machines, and relates to a through-hole filling electroplating method and system for printed circuit boards. Background Technology

[0002] In the field of integrated circuit manufacturing, especially in the manufacturing of specialized equipment for semiconductor devices such as lithography machines and etching machines, traditional via filling processes commonly employ laser blind via technology. The process flow is: "laser blind via—resin removal—micro-etching—blind via AOI—PTH—through-filling electroplating." This process has significant drawbacks: firstly, it is lengthy and costly, and requires extremely high precision in laser drilling and cleanliness at the bottom of the blind via. Residual resin residue or uneven laser energy at the bottom of the via can easily lead to delamination at the bottom, affecting reliability; secondly, uneven current distribution and insufficient flux filling capacity during the via filling process often result in defects such as "core encapsulation" and "voids," requiring repeated rework.

[0003] Therefore, a method is urgently needed to solve at least one of the above problems. Summary of the Invention

[0004] This application provides a via-hole filling electroplating method and system for printed circuit boards, aiming to address the shortcomings of existing technologies. Improvements to blind via filling primarily focus on optimizing laser equipment precision or adjusting single electroplating parameters (such as fixed current density), without overcoming the inherent limitations of the blind via structure or addressing synergistic solutions involving via structure, specialized chemicals, and dynamic current control. For example, traditional filling chemicals lack directional adsorption capacity for via depth-to-diameter ratios, failing to achieve uniform filling from the bottom to the opening; fixed current modes struggle to balance wall coverage and filling efficiency, easily leading to excessive surface deposition or incomplete filling within the via.

[0005] In a first aspect, embodiments of this application provide a method for via-hole filling electroplating for printed circuit boards, the method comprising: Laser microvia processing is performed on the printed circuit board to form microvias; the adhesive is removed from the printed circuit board with microvias. After removing the adhesive, the printed circuit board is subjected to black hole treatment or direct electroplating treatment; the treated printed circuit board is filled with an acidic copper plating solution containing leveling agent, inhibitor and accelerator, which preferentially adsorbs and inhibits deposition at the hole opening under high current density, and accelerates deposition in the low current density area, i.e., inside the hole, to achieve void-free filling from the bottom of the hole to the hole opening. During the through-hole plating process, a multi-stage plating current parameter program is used for control. In the initial stage, a low current density is used for pre-plating inside the hole to ensure uniform coverage of the hole wall. After entering the main through-hole plating stage, a pulsed or periodic reverse current is used, and the current density is increased stepwise. The through-hole is quickly filled with a special acidic copper plating through-hole plating solution. At the end of the filling process, the parameters are adjusted to ensure uniform copper thickness on the hole surface and avoid dish-shaped pits or excessive depressions.

[0006] In some embodiments, the laser microvia processing of the printed circuit board to form microvias includes: using a computer-controlled laser drilling device to process and form microvias with a diameter of 50-150 micrometers and a depth-to-diameter ratio of ≥3:1 in a designated area of ​​the printed circuit board at a laser power of 5-20 watts, a pulse frequency of 10-50 kHz, and a drilling speed of 50-200 mm / s.

[0007] In some embodiments, the process of removing adhesive from a printed circuit board with micro-vias includes: conveying the printed circuit board to an automatic adhesive removal station, immersing it in a 5-15% sodium hydroxide solution, maintaining the solution temperature at 50-80 degrees Celsius using a temperature control system, having a mechanical transmission device drive the board to oscillate at a rate of 2-5 revolutions per minute, processing for 2-10 minutes, and automatically rinsing off any remaining adhesive solution by a spray system after the adhesive removal is completed.

[0008] In some embodiments, the black hole treatment or direct electroplating treatment of the printed circuit board after adhesive removal includes: if black hole treatment is performed, the board is immersed in a carbon paste solution via a horizontal conveyor belt; the carbon particle concentration of the carbon paste solution is 10-30 g / L; the board passes through the coating area at a speed of 1-5 m / min and is cured by an infrared drying line to form a conductive carbon layer; the infrared drying line corresponds to a temperature of 80-120 degrees Celsius; if direct electroplating treatment is performed, the board is immersed in a palladium activation solution and left to stand for 1-5 minutes to complete catalytic activation; the palladium activation solution corresponds to a palladium ion concentration of 0.1-1 g / L and a temperature of 20-50 degrees Celsius.

[0009] In some embodiments, the process of electroplating the treated printed circuit board with an acidic copper plating solution includes: loading the printed circuit board into an electroplating tank, maintaining the temperature of the acidic copper plating solution at 25-45 degrees Celsius and the pH value at 1.5-3.5 through a solution circulation system, wherein the concentration of the leveling agent is 0.1-1 g / L, the concentration of the inhibitor is 5-20 g / L and the concentration of the accelerator is 0.01-0.5 g / L, and the composition of the solution is monitored in real time by an online sensor and replenished by an automatic replenishment device according to a preset ratio.

[0010] In some embodiments, the initial stage uses a low current density for in-hole pre-plating to ensure uniform coverage of the hole wall. This includes controlling the initial output of the electroplating power supply to a DC current of 0.5-2 amperes / square decimeter for 5-15 minutes, and feeding back the current density to a preset control system in real time through a current density sensor. When the copper layer thickness of the hole wall reaches 0.5-1 micrometer, the main hole filling stage is automatically triggered.

[0011] In some embodiments, after entering the main hole-filling stage, pulsed or periodic reverse current is used, and the current density is increased stepwise to quickly fill the through holes using an acidic copper plating hole-filling solution. This includes: in pulsed current mode, the frequency is set to 10-1000 Hz and the duty cycle to 10%-50%, and the current density starts from 2 amps / dm², increasing stepwise by 0.5-2 amps / dm² every 5-10 minutes until it reaches 5-15 amps / dm²; in periodic reverse current mode, the switching cycle between forward and reverse current is controlled to be 10-30 seconds, the duration of reverse current is 1-5 seconds, and the intensity of reverse current is 20%-50% of the forward current. The switching cycle between forward and reverse current, the duration of reverse current, and the intensity of reverse current are switched by the electroplating power supply according to preset rules.

[0012] In some embodiments, adjusting parameters at the end of the filling process to ensure uniform copper thickness on the hole surface and avoid dish-shaped pits or excessive depressions includes: when the filling height in the hole reaches 80%-90% of the hole depth, the electroplating power supply automatically switches to DC mode, the current density drops to 1-3 amperes / square decimeter, and continues for 5-10 minutes. At the same time, the hole surface is scanned online using a laser thickness gauge. When the standard deviation of the copper layer thickness is detected to be ≤5%, the filling is considered complete.

[0013] In some embodiments, the method further includes: acquiring process data in real time through a multi-sensor array deployed on the electroplating line, inputting the data into a pre-trained machine learning model, wherein the machine learning model dynamically optimizes the multi-stage electroplating current parameter program based on historical filling quality data to form a closed-loop feedback control; the machine learning model is periodically trained iteratively with new production data to adapt to the via filling requirements of printed circuit boards with different apertures and board thicknesses; wherein the multi-sensor array includes a current sensor, a temperature sensor, a laser thickness gauge, and a chemical composition detector; and the historical filling quality data includes core filling rate, void ratio, and copper thickness uniformity.

[0014] Secondly, this application provides a through-hole filling electroplating system for printed circuit boards, applied to the method provided in any embodiment of this application, the system comprising: The through-hole forming unit is used to perform laser micro-through-hole processing on printed circuit boards to form micro-through-holes; and to perform adhesive removal processing on printed circuit boards with micro-through-holes. The electroplating unit is used to perform black hole treatment or direct electroplating on the printed circuit board after adhesive removal. The treated printed circuit board is filled with an acidic copper plating solution containing leveling agents, inhibitors and accelerators. Under high current density, it preferentially adsorbs and inhibits deposition at the hole opening, and accelerates deposition in the low current density area, i.e., inside the hole, to achieve void-free filling from the bottom of the hole to the hole opening. The program control unit is used to control the electroplating current parameters in a multi-stage process during the hole filling electroplating process. In the initial stage, a low current density is used for pre-plating inside the hole to ensure uniform coverage of the hole wall. After entering the main hole filling stage, a pulsed or periodic reverse current is used, and the current density is increased stepwise. The through hole is quickly filled with a special acidic copper plating solution for hole filling. At the end of the filling stage, the parameters are adjusted to ensure uniform copper thickness on the hole surface and avoid dish-shaped pits or excessive depressions.

[0015] This application employs a streamlined process of "laser micro-via—adhesive removal—black hole—hole-filling electroplating," eliminating the micro-etching, AOI inspection, and PTH steps required in traditional blind hole processes. This reduces process time by 30%-50% and lowers material and equipment costs. It completely avoids the risk of delamination at the bottom of blind holes. The through-hole structure, combined with the directional adsorption characteristics of a specialized chemical, achieves void-free filling from the hole bottom to the hole opening, improving filling yield. Multi-stage current control (low-current pre-plating + pulsed / reverse current main filling + final parameter adjustment) ensures uniform coverage of the hole wall and a balance between filling speed and surface flatness, avoiding defects such as "dish-shaped pits" and "excessive depressions." Through the synergistic effect of leveling agents, inhibitors, and accelerators in the acidic copper plating solution, it can accommodate micro-vias with a depth-to-diameter ratio ≥3:1 (diameter 50-150 micrometers), overcoming the limitations of traditional processes on hole depth-to-diameter ratios.

[0016] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart illustrating the steps of a through-hole filling electroplating method for printed circuit boards according to an embodiment of this application; Figure 2 This is a schematic block diagram of a through-hole filling electroplating system for printed circuit boards provided in one embodiment of this application; Figure 3This is a schematic block diagram of the structure of a computer device provided in an embodiment of this application.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0022] It should be understood that, in order to clearly describe the technical solutions of the embodiments of the present invention, the terms "first" and "second" are used in the embodiments of the present invention to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and the terms "first" and "second" are not necessarily different.

[0023] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0024] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0025] In the field of printed circuit board (PCB) manufacturing, traditional via filling processes commonly employ laser blind via technology, with a process flow of "laser blind via—resin removal—micro-etching—blind via AOI—PTH—through-filling electroplating". This process has significant drawbacks: on the one hand, it is lengthy and costly, and requires extremely high precision in laser drilling and cleanliness at the bottom of the blind via. It is prone to delamination at the bottom of the blind via due to residual resin or uneven laser energy, affecting reliability; on the other hand, during the via filling process, defects such as "core encapsulation" and "void" often occur due to uneven current distribution and insufficient filling capacity of the filler, requiring repeated rework.

[0026] In existing technologies, improvements to blind via filling mainly focus on optimizing the precision of laser equipment or adjusting single electroplating parameters (such as fixing the current density), but they do not overcome the limitations of the blind via structure itself, nor do they address the synergistic solutions of through-hole structures with specialized chemicals and dynamic current control. For example, traditional filling chemicals lack directional adsorption capacity for the through-hole depth-to-diameter ratio, making it impossible to achieve uniform filling from the bottom to the opening of the hole; fixed current modes struggle to balance hole wall coverage and filling efficiency, easily leading to excessive surface deposition or incomplete filling within the holes.

[0027] To resolve the above issues, please refer to... Figure 1 This application provides a through-hole filling electroplating method for printed circuit boards, applicable to computer equipment. The computer equipment can be deployed on a single server or server cluster. It can also be deployed on handheld terminals, laptops, wearable devices, or robots, etc.

[0028] The provided through-hole filling electroplating method for printed circuit boards includes steps S101 to S103. Details are as follows: Step S101. Perform laser microvia processing on the printed circuit board to form microvias; perform adhesive removal processing on the printed circuit board with microvias.

[0029] Specifically, laser micro-via processing uses high-precision laser equipment to process micron-sized through holes (micro-vias) on printed circuit boards (PCBs), overcoming the limitations of traditional mechanical drilling in terms of depth-to-diameter ratio (e.g., ≥10:1) and hole diameter accuracy (e.g., ≤50μm), and ensuring that the hole wall verticality and surface roughness meet the requirements of electroplating.

[0030] Resin removal treatment removes the carbonized resin residue (resin residue) generated during laser processing, preventing the residue from causing insufficient adhesion between the hole wall and the coating or insulation inside the hole, which would affect subsequent conductivity and hole filling quality.

[0031] Laser processing utilizes ultraviolet laser (wavelength 355nm) or femtosecond laser equipment, equipped with a CCD vision alignment system, achieving a positioning accuracy of ≤±5μm. The laser energy (50-100mJ), pulse frequency (20-100kHz), and scanning speed (50-200mm / s) are adjusted according to design requirements to process micro-holes with diameters of 10-100μm and aspect ratios of 5:1 to 15:1.

[0032] The adhesive removal process employs either chemical removal using potassium permanganate solution (concentration 8-15 g / L, temperature 60-80℃, pH 12-14) or physical removal using plasma (oxygen plasma, power 100-300 W, treatment time 5-15 min). Following adhesive removal, the pores are ultrasonically cleaned with deionized water (water temperature 40-60℃, time 3-5 min) to ensure no residual adhesive or chemical agents remain on the pore walls.

[0033] Step S102. Perform black hole treatment or direct electroplating on the printed circuit board after degumming; use an acidic copper plating solution to fill the holes on the treated printed circuit board. The acidic copper plating solution contains leveling agents, inhibitors and accelerators, which preferentially adsorb and inhibit deposition at the hole opening under high current density, and accelerate deposition in the low current density area, i.e., inside the hole, to achieve void-free filling from the bottom of the hole to the hole opening.

[0034] Specifically, black hole treatment (optional): For non-conductive hole walls (such as dielectric layers), a thin conductive layer is formed through conductive treatment (such as carbon particle adhesion), replacing the traditional chemical copper plating process, simplifying the process and improving the conductivity of the hole walls.

[0035] Acidic copper plating for filling holes uses a special solution (containing leveling agents, inhibitors, and accelerators) to achieve "bottom-priority filling" by utilizing electrochemical adsorption characteristics: inhibitors (such as sulfur-containing organic compounds) are preferentially adsorbed in the high current density area at the hole opening, inhibiting copper deposition; accelerators (such as chloride ions and organic amines) promote copper ion reduction in the low current density area inside the hole, achieving void-free filling from the bottom to the opening; leveling agents (such as polydisulfide compounds) adjust the surface smoothness of the plating layer and reduce surface roughness.

[0036] The corresponding process for black hole treatment is as follows: pore wall activation (palladium activation solution, concentration 0.5-1g / L, temperature 30-40℃, time 1-3min) → carbon paste coating (carbon particles with a diameter of 0.1-0.5μm, solid content 5-10%, uniformly attached by vacuum adsorption or horizontal coating machine) → thermal curing (temperature 80-120℃, time 10-20min) to form a conductive layer with a thickness of 0.1-0.3μm.

[0037] The chemical composition for acidic copper plating with hole filling is as follows: copper sulfate: 80-120 g / L, sulfuric acid: 150-200 g / L, chloride ions: 50-80 ppm; leveling agent: 0.1-0.5 mL / L, inhibitor: 5-10 mL / L, accelerator: 1-3 mL / L; pH: 1.0-1.8, temperature: 25-35℃, solution circulation filtration (filter cartridge precision ≤1 μm).

[0038] Electroplating equipment is equipped with a vertical continuous electroplating line (VCP line) or a horizontal electroplating line, with an anode titanium basket (containing phosphorus copper balls, phosphorus content 0.03-0.07%) and a cathode moving device (speed 5-10m / min).

[0039] Step S103. During the hole-filling electroplating process, a multi-stage electroplating current parameter program is used for control. In the initial stage, a low current density is used for pre-plating inside the hole to ensure uniform coverage of the hole wall. After entering the main hole-filling stage, a pulsed or periodic reverse current is used, and the current density is increased stepwise. The through hole is quickly filled with a special acidic copper plating solution for hole filling. At the end of the filling stage, the parameters are adjusted to ensure uniform copper thickness on the hole surface and avoid dish-shaped pits or excessive depressions.

[0040] Specifically, by dynamically adjusting the current density and waveform in stages, the uniformity of hole wall coverage and the filling efficiency are balanced, avoiding excessive surface deposition or voids in the holes caused by the traditional fixed current mode: Initial stage (pre-plating): Low current density ensures no missed plating and uniform coverage on the hole wall; Main filling stage: Pulsed / periodic reverse current combined with stepped current rise, utilizing the "super filling" capability of the solution to accelerate the filling in the hole and suppress copper nodules at the edge of the hole; Final filling stage: Adjusting parameters to make the copper thickness on the hole surface uniform, avoiding dish-shaped pits (recess depth ≤ 5μm) or excessive depression.

[0041] The initial stage (pre-plating) includes: current mode: direct current (DC), current density 1-3 ASD (amperes / dm²); time: 5-10 min, ensuring that the plating thickness on the hole wall is ≥0.5μm, and that the coverage is uniform and free of pores.

[0042] The main via filling stage includes: Current mode: Pulsed current (PC) or periodic reverse current (PRC): Pulsed current: frequency 50-200Hz, duty cycle 10-30%, forward current density increases stepwise from 5 ASD to 15 ASD (increasing by 2-3 ASD every 10 min), reverse current density is 20-30% of the forward current, duration 1-2 ms; Periodic reverse current includes: forward current density 5-15 ASD, reverse current density 1-3 ASD, period 10-30 s; Purpose: to reduce via deposits at the via opening by utilizing the "tip dissolution" effect of pulsed / reverse current, while simultaneously increasing the copper ion deposition rate inside the via through stepwise current increase, with a filling rate ≥2 μm / min. The final filling stage includes: Current mode: DC, current density reduced to 3-5 ASD; Time: 5-10 min, ensuring surface copper thickness uniformity ≤±5%, and full via filling (no voids detected by cross-section, filling rate ≥99%).

[0043] In some embodiments, the laser microvia processing of the printed circuit board to form microvias includes: using a computer-controlled laser drilling device to process and form microvias with a diameter of 50-150 micrometers and a depth-to-diameter ratio of ≥3:1 in a designated area of ​​the printed circuit board at a laser power of 5-20 watts, a pulse frequency of 10-50 kHz, and a drilling speed of 50-200 mm / s.

[0044] By precisely controlling the laser drilling equipment with a computer, high-precision micro-through holes are processed in designated areas of printed circuit boards, ensuring that the diameter and depth-to-diameter ratio of the holes meet the requirements of the hole filling process.

[0045] The equipment control uses a computer program to set the laser drilling path and parameters, and links the motion axes of the laser equipment (such as the X / Y axes) to achieve micron-level positioning.

[0046] Process parameters: Laser power: 5-20 watts (adjust energy density to avoid carbonization of the hole wall); Pulse frequency: 10-50 kHz (control drilling speed and heat-affected zone of the hole wall); Drilling speed: 50-200 mm / s (match material thickness and hole diameter requirements); Processing target: form micro-through holes with a diameter of 50-150 micrometers, a depth-to-diameter ratio of ≥3:1, a hole wall perpendicularity error of ≤5°, and a surface roughness Ra of ≤2.5μm.

[0047] In some embodiments, the process of removing adhesive from a printed circuit board with micro-vias includes: conveying the printed circuit board to an automatic adhesive removal station, immersing it in a 5-15% sodium hydroxide solution, maintaining the solution temperature at 50-80 degrees Celsius using a temperature control system, having a mechanical transmission device drive the board to oscillate at a rate of 2-5 revolutions per minute, processing for 2-10 minutes, and automatically rinsing off any remaining adhesive solution by a spray system after the adhesive removal is completed.

[0048] Sodium hydroxide solution is used to chemically remove adhesive from printed circuit boards after laser drilling. Mechanical oscillation and temperature control systems are used to improve the efficiency and uniformity of adhesive removal.

[0049] The printed circuit board is fed into the desmearing tank by a conveyor belt. The tank is equipped with a temperature control system (accuracy ±2℃) and a mechanical oscillation device.

[0050] Process parameters: Sodium hydroxide concentration: 5-15% (adjust corrosivity according to different resin materials); Solution temperature: 50-80℃ (to improve chemical reactivity); Swinging rate: 2-5 rpm (to enhance solution convection and flush out resin residue from the hole wall); Processing time: 2-10 minutes (adjust according to hole depth and resin residue thickness); Post-treatment: After degumming, the solution undergoes multi-stage spraying (water pressure ≥0.5MPa) and ultrasonic cleaning (frequency 40kHz) to ensure no chemical residue remains.

[0051] In some embodiments, the black hole treatment or direct electroplating treatment of the printed circuit board after adhesive removal includes: if black hole treatment is performed, the board is immersed in a carbon paste solution via a horizontal conveyor belt; the carbon particle concentration of the carbon paste solution is 10-30 g / L; the board passes through the coating area at a speed of 1-5 m / min and is cured by an infrared drying line to form a conductive carbon layer; the infrared drying line corresponds to a temperature of 80-120 degrees Celsius; if direct electroplating treatment is performed, the board is immersed in a palladium activation solution and left to stand for 1-5 minutes to complete catalytic activation; the palladium activation solution corresponds to a palladium ion concentration of 0.1-1 g / L and a temperature of 20-50 degrees Celsius.

[0052] Depending on the conductivity of the hole wall, either black hole treatment or direct electroplating is selected. Black hole treatment forms a conductive layer by coating with carbon paste, while direct electroplating uses palladium activating solution to catalyze metal deposition.

[0053] The black hole treatment process includes: carbon slurry solution: carbon particle concentration of 10-30 g / L (particle size 0.1-0.5 μm, to ensure conductivity), which is immersed in the coating tank at a speed of 1-5 m / min via a horizontal conveyor belt to form a carbon layer with a thickness of 0.2-0.5 μm; curing process: infrared drying line temperature of 80-120℃ for 5-10 minutes to make the carbon particles firmly adhere to the hole wall.

[0054] The direct electroplating route includes: palladium activation solution: palladium ion concentration 0.1-1 g / L (catalyzing the reduction of copper ions), temperature 20-50℃, standing for 1-5 minutes to allow the pore walls to adsorb catalytic active sites.

[0055] In some embodiments, the process of electroplating the treated printed circuit board with an acidic copper plating solution includes: loading the printed circuit board into an electroplating tank, maintaining the temperature of the acidic copper plating solution at 25-45 degrees Celsius and the pH value at 1.5-3.5 through a solution circulation system, wherein the concentration of the leveling agent is 0.1-1 g / L, the concentration of the inhibitor is 5-20 g / L and the concentration of the accelerator is 0.01-0.5 g / L, and the composition of the solution is monitored in real time by an online sensor and replenished by an automatic replenishment device according to a preset ratio.

[0056] By utilizing the electrochemical properties of acidic copper plating solutions, a circulation system and online monitoring are used to maintain the stability of the solution composition, enabling directional filling.

[0057] The composition and control of the chemical solution include: basic components: copper sulfate 80-120 g / L, sulfuric acid 150-200 g / L, chloride ion 50-80 ppm; additive concentrations: leveling agent 0.1-1 g / L (such as polyether compounds), inhibitor 5-20 g / L (such as sulfur-containing organic compounds), accelerator 0.01-0.5 g / L (such as ethylenediamine); environmental control: temperature 25-45℃ (adjusted by refrigeration / heating units), pH 1.5-3.5 (adjusted online with sulfuric acid / sodium hydroxide); circulation system: the chemical solution is circulated through a filter cartridge with a filtration accuracy ≤1 μm (flow rate 10-20 m³ / L). 3 / h), online sensors (such as pH meters and conductivity meters) monitor the components in real time, and the automatic replenishment device replenishes the consumed medicine according to the preset ratio.

[0058] In some embodiments, the initial stage uses a low current density for in-hole pre-plating to ensure uniform coverage of the hole wall. This includes controlling the initial output of the electroplating power supply to a DC current of 0.5-2 amperes / square decimeter for 5-15 minutes, and feeding back the current density to a preset control system in real time through a current density sensor. When the copper layer thickness of the hole wall reaches 0.5-1 micrometer, the main hole filling stage is automatically triggered.

[0059] Low current density DC pre-plating is used in the initial stage of electroplating, and automated stage switching is achieved through current density sensors and thickness detection to ensure full coverage of the hole wall.

[0060] Pre-plating control includes: Current mode: DC, initial current density 0.5-2 A / dm² (ASD) to avoid high current causing preferential deposition at the orifice; Duration: 5-15 minutes, during which the current density sensor (accuracy ±0.1ASD) provides real-time feedback to the control system; Switching condition: When the copper layer thickness on the orifice wall (measured by a coulomb gauge or X-ray thickness gauge) reaches 0.5-1 micrometer, the main orifice filling stage is automatically triggered.

[0061] In some embodiments, after entering the main hole-filling stage, pulsed or periodic reverse current is used, and the current density is increased stepwise to quickly fill the through holes using an acidic copper plating hole-filling solution. This includes: in pulsed current mode, the frequency is set to 10-1000 Hz and the duty cycle to 10%-50%, and the current density starts from 2 amps / dm², increasing stepwise by 0.5-2 amps / dm² every 5-10 minutes until it reaches 5-15 amps / dm²; in periodic reverse current mode, the switching cycle between forward and reverse current is controlled to be 10-30 seconds, the duration of reverse current is 1-5 seconds, and the intensity of reverse current is 20%-50% of the forward current. The switching cycle between forward and reverse current, the duration of reverse current, and the intensity of reverse current are switched by the electroplating power supply according to preset rules.

[0062] During the main filling stage, pulsed or periodic reverse current is used in combination with stepped up current to utilize electrochemical effects to suppress deposits at the orifice and accelerate filling within the orifice.

[0063] The pulse current mode includes: frequency: 10-1000 Hz (high frequency suppression of tip effect), duty cycle 10%-50% (adjusting average current density); current density: starting from 2 ASD, increasing by 0.5-2 ASD every 5-10 minutes until 5-15 ASD (stepped current rise to match chemical adsorption characteristics); periodic reverse current (PRC) mode: switching cycle: 10-30 seconds, reverse current lasts for 1-5 seconds, intensity is 20%-50% of the forward current (dissolving excess copper at the orifice, balancing the deposition rate inside and outside the orifice); equipment support: the electroplating power supply has multi-waveform output function (such as pulse, PRC), and parameters are automatically switched through preset programs.

[0064] In some embodiments, adjusting parameters at the end of the filling process to ensure uniform copper thickness on the hole surface and avoid dish-shaped pits or excessive depressions includes: when the filling height in the hole reaches 80%-90% of the hole depth, the electroplating power supply automatically switches to DC mode, the current density drops to 1-3 amperes / square decimeter, and continues for 5-10 minutes. At the same time, the hole surface is scanned online using a laser thickness gauge. When the standard deviation of the copper layer thickness is detected to be ≤5%, the filling is considered complete.

[0065] At the end of the filling process, the current density is reduced and switched to DC mode. The uniformity of copper thickness is monitored online using a laser thickness gauge to ensure a smooth hole surface.

[0066] The stage switching condition is determined by real-time imaging or coulomb calculation. When the filling height inside the hole reaches 80%-90%, the final processing is triggered. Process parameters: Current mode: DC, current density reduced to 1-3 ASD (to reduce surface deposition rate); Duration: 5-10 minutes, during which a laser thickness gauge (accuracy ±1μm) performs a grid scan on the hole surface; Judgment criteria: when the standard deviation of copper thickness in the detection area is ≤5%, the filling is considered complete, avoiding dish-shaped pits (depression depth >5μm) or excessive depression.

[0067] In some embodiments, the method further includes: acquiring process data in real time through a multi-sensor array deployed on the electroplating line, inputting the data into a pre-trained machine learning model, wherein the machine learning model dynamically optimizes the multi-stage electroplating current parameter program based on historical filling quality data to form a closed-loop feedback control; the machine learning model is periodically trained iteratively with new production data to adapt to the via filling requirements of printed circuit boards with different apertures and board thicknesses; wherein the multi-sensor array includes a current sensor, a temperature sensor, a laser thickness gauge, and a chemical composition detector; and the historical filling quality data includes core filling rate, void ratio, and copper thickness uniformity.

[0068] By introducing industrial IoT and machine learning technologies, and collecting data in real time through multiple sensors, a closed-loop feedback system is built to dynamically optimize electroplating parameters and improve process adaptability.

[0069] The data acquisition layer includes: a sensor array: a current sensor (monitoring real-time current density), a temperature sensor (medicine temperature), a laser thickness gauge (copper layer thickness), and a medicine component detector (ion concentration); data frequency: ≥10 acquisitions per second, stored to edge computing nodes.

[0070] The machine learning model includes: input features: aperture, plate thickness, plating solution composition, current parameters, and temperature; output target: optimized multi-stage current parameters (such as stage duration, current density, and waveform); training mechanism: periodically iterating the model using new production data (including quality indicators such as core filling rate, void rate, and copper thickness uniformity), supporting adaptive adjustment for different apertures (10-150μm) and plate thicknesses (0.5-3mm). Closed-loop control: the model output parameters are synchronized to the electroplating power supply in real time, forming a dynamic closed loop of "data acquisition - model optimization - parameter adjustment" to improve the filling yield (target ≥99%).

[0071] In some embodiments, to address the issue of component fluctuations caused by the reliance on "post-event detection" in traditional medicine rehydration, a multi-sensor data fusion and machine learning prediction model are used to predict the consumption rate of additives (leveling agents, inhibitors, accelerators) in real time, adjust the rehydration volume in advance, achieve precise maintenance of medicine components, and avoid filling defects (such as voids, copper nodules, and surface roughness) caused by additive decay.

[0072] The data acquisition layer uses an online high-performance liquid chromatograph (HPLC) to detect additive concentration (accuracy ±0.01 g / L), temperature sensor (±1℃), current sensor (±0.1 ASD), and chemical flow sensor (±0.1 m³ / h), and collects process data in real time (sampling frequency ≥1 Hz). Associate historical filling quality data (such as void ratio and copper thickness uniformity) and mark the corresponding chemical composition thresholds for "qualified" (void ratio ≤ 0.5%, copper thickness uniformity ≤ ±5%) and "unqualified" (void ratio > 0.5% or copper thickness uniformity > ±5%).

[0073] The model is trained using "temperature, current density, drug flow rate, and initial additive concentration" as input features and "additive consumption rate (concentration decrease per unit time, e.g., g / L·min)" as output label to train a Long Short-Term Memory (LSTM) network model (good at time series prediction). The model is optimized using "unqualified" samples to ensure that the model can issue an early warning when the predicted consumption rate exceeds the "qualified threshold".

[0074] The dynamic replenishment logic receives current process data in real time through a model and predicts the additive consumption rate within the next 5-10 minutes. Based on the prediction results, it calculates the replenishment volume (formula: replenishment volume = consumption rate × time × electroplating tank volume × additive purity) and adjusts the pump speed of the automatic replenishment device according to a preset ratio (e.g., leveling agent: inhibitor: accelerator = 1:5:0.1). After replenishment, it verifies in real time through HPLC whether the components have returned to the target range (e.g., leveling agent 0.1-1 g / L, inhibitor 5-20 g / L, accelerator 0.01-0.5 g / L). If the target is not met, it triggers fine-tuning again.

[0075] Compared with the traditional "post-treatment replenishment", the fluctuation range of additive concentration has been reduced from ±15% to ±5%, and the filling defect rate (void, copper nodule) has decreased by more than 40%. The model is iteratively trained every 7 days with new production data to adapt to the decay characteristics of different batches of medicine (such as the accelerated consumption of accelerators due to high summer temperatures).

[0076] In some embodiments, to address the problem that the "fixed parameters" of traditional laser drilling cannot adapt to different board thicknesses, hole diameters, and materials, machine learning and process knowledge are used to predict the optimal laser parameters (power, pulse frequency, drilling speed) in real time based on the board thickness, hole diameter, and material type (such as FR4, high-frequency Rogers material) of the printed circuit board, ensuring that the hole wall perpendicularity (error ≤ 5°) and surface roughness (Ra ≤ 2.5 μm) meet the filling requirements.

[0077] Data acquisition involves collecting historical laser drilling data, including plate thickness (0.5-3mm), hole diameter (50-150μm), material type (FR4, Rogers 4350), laser parameters (power 5-20W, frequency 10-50kHz, speed 50-200mm / s), and corresponding hole wall quality data (perpendicularity, roughness); and marking the parameter boundaries between "high-quality holes" (perpendicularity ≤5°, Ra≤2.5μm) and "low-quality holes" (perpendicularity >5° or Ra >2.5μm).

[0078] The model training uses "plate thickness, hole diameter, and material type" as input features and "laser power, pulse frequency, and drilling speed" as output labels to train a gradient boosting tree (GBDT) model (which is good at handling structured data and can output the importance ranking of parameters). By combining process knowledge (such as thick plates requiring higher power to penetrate and small apertures requiring higher frequencies to reduce thermal impact), constraints are imposed on the model output (such as power ≥ 15W when plate thickness > 2mm; frequency ≥ 30kHz when aperture < 80μm).

[0079] When a new batch of printed circuit boards enters the laser drilling station, the CCD vision system automatically identifies the board thickness (through edge contours), hole diameter (through design documents), and material type (through barcode scanning). These parameters are input into the model, and the optimal laser parameters are output (e.g., for a board thickness of 2.5mm, a hole diameter of 80μm, and FR4 material, the output power is 18W, the frequency is 35kHz, and the speed is 120mm / s). The motion control card of the laser equipment receives the parameters and adjusts the laser generator (power), pulse generator (frequency), and servo motor (speed) in real time to achieve adaptive hole processing.

[0080] In some embodiments, to address the high rework costs caused by "post-processing defect detection" in traditional hole filling processes, multi-sensor data and deep learning models are used to predict the probability of filling defects (such as voids, copper nodules, and dish-shaped pits) in real time. When the probability exceeds a threshold, process parameters (such as current density and chemical additive concentration) are proactively adjusted to "prevent problems before they occur".

[0081] Defects were defined and labeled using an X-ray inspection system (to scan the filling status inside the hole in real time) and a laser thickness gauge (to scan the copper thickness on the surface). Defect types were defined as follows: voids: unfilled area inside the hole > 5%; copper nodules: copper thickness at the hole opening > twice that of the surrounding area (e.g., if the surrounding copper thickness is 15μm, the hole opening thickness is > 30μm); dish-shaped pits: the depth of the hole surface depression > 5μm. Multiple batches of process data (current, temperature, chemical concentration, copper thickness) and corresponding defect labels were collected to construct a training dataset.

[0082] The model training uses "real-time current density (ASD), solution temperature (°C), inhibitor concentration (g / L), accelerator concentration (g / L), and copper thickness growth rate in the pore (μm / min)" as input features and "void probability, copper nodule probability, and dish-shaped pit probability" as output labels to train a convolutional neural network (CNN) model (which is good at feature extraction of time series data). A confusion matrix optimization model is used to ensure that the accuracy of defect prediction is ≥90% and the recall is ≥85% (i.e., to minimize the number of missed defects).

[0083] The model receives process data in real time and outputs the probability of each defect (e.g., void probability = 85%, copper nodule probability = 10%, dish-shaped pit probability = 5%). When the probability of a defect exceeds a threshold (e.g., void probability > 70%), an intervention strategy is triggered: If the void probability is high: increase the accelerator concentration (e.g., from 0.2 g / L to 0.3 g / L), or reduce the current density during the main filling stage (e.g., from 12 ASD to 10 ASD) to enhance the deposition rate in the hole; If the copper nodule probability is high: increase the inhibitor concentration (e.g., from 15 g / L to 18 g / L), or increase the reverse time of the pulse current (e.g., from 2 ms to 3 ms) to dissolve excess copper at the hole opening; If the dish-shaped pit probability is high: reduce the current density at the end of the filling stage (e.g., from 4 ASD to 3 ASD), or increase the leveling agent concentration (e.g., from 0.5 g / L to 0.8 g / L) to improve surface smoothness.

[0084] In some embodiments, to address the poor synergy problem caused by the independent adjustment of current parameters and chemical parameters in traditional processes (e.g., high current density requires high concentrations of inhibitors, but traditional methods do not link them), a multi-objective optimization algorithm combined with machine learning is used to find the optimal combination of current parameters (pulse frequency, duty cycle) and chemical parameters (inhibitor, accelerator concentration) to achieve a balance between maximizing the filling rate, minimizing the void ratio, and optimizing the copper thickness uniformity.

[0085] The objective function is defined as follows: Maximize the filling rate (unit: μm / min): Filling rate = Copper thickness growth rate in the hole; Minimize the void ratio (unit: %): Void ratio = Area of ​​unfilled region in the hole / Hole area; Minimize copper thickness uniformity (unit: %): Copper thickness uniformity = (Maximum copper thickness - Minimum copper thickness) / Average copper thickness × 100%.

[0086] The variable definitions include: current parameters: pulse frequency (10-1000Hz), duty cycle (10%-50%), forward current density (2-15ASD); drug parameters: inhibitor concentration (5-20g / L), accelerator concentration (0.01-0.5g / L).

[0087] The optimization process includes: Data acquisition: Real-time acquisition of current parameters, chemical parameters, and filling quality data (fill rate, void ratio, copper thickness uniformity) through a multi-sensor array; Model construction: Fitting the mapping relationship between "variables → objective function" using a random forest (RF) model (e.g., current frequency ↑ → filling rate ↑, but void ratio may ↑; inhibitor concentration ↑ → void ratio ↓, but filling rate may ↓); Multi-objective optimization: Using a non-dominated sorting genetic algorithm (NSGA-II), with the RF model as a surrogate model, searching for Pareto optimal solutions for the variables (i.e., solutions that cannot improve one objective without worsening another); Solution selection: Selecting the optimal combination from the Pareto front based on production needs (e.g., selecting solutions with high filling rates if efficiency is prioritized, and selecting solutions with low void ratios if quality is prioritized).

[0088] When a new batch of printed circuit boards enters the electroplating station, the real-time application logic selects the corresponding optimal parameter combination from the pre-calculated Pareto solution library based on its aperture (50-150μm) and board thickness (0.5-3mm). For example, when the aperture is 80μm and the board thickness is 2mm, the optimal parameters are selected: pulse frequency 200Hz, duty cycle 25%, forward current 10ASD, inhibitor 12g / L, and accelerator 0.2g / L. The electroplating power supply and automatic replenishment device receive the parameters and adjust the current waveform and chemical composition in real time.

[0089] Compared to independently adjusted parameters, the fill rate increased by 40% (from 1.5μm / min to 2.1μm / min), the void ratio decreased by 50% (from 1.0% to 0.5%), and the copper thickness uniformity improved by 30% (from ±8% to ±5.5%). The Pareto database is updated quarterly with new data to adapt to the changing needs of different products.

[0090] In some embodiments, to address the problem of "high trial-and-error costs" in traditional processes (such as the need for multiple experiments to adjust parameters, which is time-consuming and material-intensive), a digital twin model of the printed circuit board via filling process is constructed. The filling effect of different process parameters (laser, current, chemical) is predicted through virtual simulation, and the optimal parameters are set in advance to reduce the actual number of trial and error attempts.

[0091] The construction of the digital twin model includes: the physical layer collecting geometric data (hole depth, hole diameter), process data (current, temperature), and quality data (copper thickness, void ratio) of the actual hole-filling process through multiple sensors (laser displacement sensor, current sensor, temperature sensor); the virtual layer constructing a thermo-mechanical coupling model of laser drilling using finite element analysis (FEA) (simulating the melting and evaporation of the hole wall by laser energy), and constructing a mass transfer-electrochemical model of the electroplating process using computational fluid dynamics (CFD) (simulating the diffusion and deposition of copper ions in the hole); and data fusion by inputting the data collected by the physical layer into the virtual layer to calibrate model parameters (such as laser absorption coefficient, copper ion diffusion coefficient) to ensure that the error between the virtual model and the actual process is ≤10%.

[0092] The virtual trial-and-error logic inputs the design parameters (hole diameter, board thickness, number of layers) of a new batch of printed circuit boards into a digital twin model when via filling is required. The model simulates different combinations of process parameters (such as laser power of 15W and 20W, current density of 10ASD and 12ASD, inhibitor of 10g / L and 15g / L) and outputs virtual filling effects (fill rate, void ratio, copper thickness uniformity). Based on the virtual results, the optimal parameter combination is selected (such as when the simulated display power is 18W, current is 10ASD, inhibitor is 12g / L, filling rate is 2.0μm / min, void ratio is 0.4%, copper thickness uniformity is ±5%).

[0093] In practical applications, virtual optimal parameters are sent to laser drilling and electroplating equipment as initial parameter settings. During actual processing, the digital twin model is updated in real time using multi-sensor data. If the deviation between the virtual and actual results exceeds 10% (e.g., the actual filling rate is 1.8 μm / min, while the virtual rate is 2.0 μm / min), the model parameters are adjusted (e.g., the copper ion diffusion coefficient is corrected) to improve the accuracy of subsequent simulations.

[0094] Compared to the traditional trial-and-error method, the number of trials is reduced from 5 to 1, the trial time is shortened from 2 days to 4 hours, and material loss is reduced by 70%; the digital twin model is calibrated with new production data every six months to ensure its adaptability.

[0095] Please see Figure 2 As shown, Figure 2 This is a schematic diagram of the structure of a through-hole filling electroplating system 200 for printed circuit boards provided in this application embodiment. The through-hole filling electroplating system 200 for printed circuit boards is used to perform the steps of the through-hole filling electroplating method for printed circuit boards shown in the above embodiments. The through-hole filling electroplating system 200 for printed circuit boards can be a single server or a server cluster, or it can be a terminal, such as a handheld terminal, laptop computer, wearable device, or robot.

[0096] like Figure 2 As shown, the through-hole filling electroplating system 200 for printed circuit boards includes: The through-hole forming unit 201 is used to perform laser micro-through-hole processing on the printed circuit board to form micro-through-holes; and to perform adhesive removal processing on the printed circuit board with micro-through-holes. The electroplating unit 202 is used to perform black hole treatment or direct electroplating on the printed circuit board after adhesive removal. The treated printed circuit board is electroplated with an acidic copper plating solution containing leveling agent, inhibitor and accelerator. Under high current density, it preferentially adsorbs and inhibits deposition at the hole opening, and accelerates deposition in the low current density area, i.e., inside the hole, to achieve void-free filling from the bottom of the hole to the hole opening. The program control unit 203 is used to control the electroplating current parameters in a multi-stage process during the hole filling electroplating process. In the initial stage, a low current density is used for pre-plating inside the hole to ensure uniform coverage of the hole wall. After entering the main hole filling stage, a pulsed or periodic reverse current is used, and the current density is increased stepwise. The through hole is quickly filled with a special acidic copper plating solution. At the end of the filling stage, the parameters are adjusted to ensure uniform copper thickness on the hole surface and avoid dish-shaped pits or excessive depressions.

[0097] In some embodiments, the laser microvia processing of the printed circuit board to form microvias includes: using a computer-controlled laser drilling device to process and form microvias with a diameter of 50-150 micrometers and a depth-to-diameter ratio of ≥3:1 in a designated area of ​​the printed circuit board at a laser power of 5-20 watts, a pulse frequency of 10-50 kHz, and a drilling speed of 50-200 mm / s.

[0098] In some embodiments, the process of removing adhesive from a printed circuit board with micro-vias includes: conveying the printed circuit board to an automatic adhesive removal station, immersing it in a 5-15% sodium hydroxide solution, maintaining the solution temperature at 50-80 degrees Celsius using a temperature control system, having a mechanical transmission device drive the board to oscillate at a rate of 2-5 revolutions per minute, processing for 2-10 minutes, and automatically rinsing off any remaining adhesive solution by a spray system after the adhesive removal is completed.

[0099] In some embodiments, the black hole treatment or direct electroplating treatment of the printed circuit board after adhesive removal includes: if black hole treatment is performed, the board is immersed in a carbon paste solution via a horizontal conveyor belt; the carbon particle concentration of the carbon paste solution is 10-30 g / L; the board passes through the coating area at a speed of 1-5 m / min and is cured by an infrared drying line to form a conductive carbon layer; the infrared drying line corresponds to a temperature of 80-120 degrees Celsius; if direct electroplating treatment is performed, the board is immersed in a palladium activation solution and left to stand for 1-5 minutes to complete catalytic activation; the palladium activation solution corresponds to a palladium ion concentration of 0.1-1 g / L and a temperature of 20-50 degrees Celsius.

[0100] In some embodiments, the process of electroplating the treated printed circuit board with an acidic copper plating solution includes: loading the printed circuit board into an electroplating tank, maintaining the temperature of the acidic copper plating solution at 25-45 degrees Celsius and the pH value at 1.5-3.5 through a solution circulation system, wherein the concentration of the leveling agent is 0.1-1 g / L, the concentration of the inhibitor is 5-20 g / L and the concentration of the accelerator is 0.01-0.5 g / L, and the composition of the solution is monitored in real time by an online sensor and replenished by an automatic replenishment device according to a preset ratio.

[0101] In some embodiments, the initial stage uses a low current density for in-hole pre-plating to ensure uniform coverage of the hole wall. This includes controlling the initial output of the electroplating power supply to a DC current of 0.5-2 amperes / square decimeter for 5-15 minutes, and feeding back the current density to a preset control system in real time through a current density sensor. When the copper layer thickness of the hole wall reaches 0.5-1 micrometer, the main hole filling stage is automatically triggered.

[0102] In some embodiments, after entering the main hole-filling stage, pulsed or periodic reverse current is used, and the current density is increased stepwise to quickly fill the through holes using an acidic copper plating hole-filling solution. This includes: in pulsed current mode, the frequency is set to 10-1000 Hz and the duty cycle to 10%-50%, and the current density starts from 2 amps / dm², increasing stepwise by 0.5-2 amps / dm² every 5-10 minutes until it reaches 5-15 amps / dm²; in periodic reverse current mode, the switching cycle between forward and reverse current is controlled to be 10-30 seconds, the duration of reverse current is 1-5 seconds, and the intensity of reverse current is 20%-50% of the forward current. The switching cycle between forward and reverse current, the duration of reverse current, and the intensity of reverse current are switched by the electroplating power supply according to preset rules.

[0103] In some embodiments, adjusting parameters at the end of the filling process to ensure uniform copper thickness on the hole surface and avoid dish-shaped pits or excessive depressions includes: when the filling height in the hole reaches 80%-90% of the hole depth, the electroplating power supply automatically switches to DC mode, the current density drops to 1-3 amperes / square decimeter, and continues for 5-10 minutes. At the same time, the hole surface is scanned online using a laser thickness gauge. When the standard deviation of the copper layer thickness is detected to be ≤5%, the filling is considered complete.

[0104] In some embodiments, the method further includes: acquiring process data in real time through a multi-sensor array deployed on the electroplating line, inputting the data into a pre-trained machine learning model, wherein the machine learning model dynamically optimizes the multi-stage electroplating current parameter program based on historical filling quality data to form a closed-loop feedback control; the machine learning model is periodically trained iteratively with new production data to adapt to the via filling requirements of printed circuit boards with different apertures and board thicknesses; wherein the multi-sensor array includes a current sensor, a temperature sensor, a laser thickness gauge, and a chemical composition detector; and the historical filling quality data includes core filling rate, void ratio, and copper thickness uniformity.

[0105] It should be noted that those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the through-hole filling electroplating system and each module for printed circuit boards described above can be referred to the corresponding content in the various embodiments of the through-hole filling electroplating method for printed circuit boards, and will not be repeated here.

[0106] The above-described electroplating method for filling through-holes in printed circuit boards can be implemented as a computer program, which can be used in various ways, such as... Figure 2 It runs on the device shown.

[0107] Please see Figure 3 , Figure 3 This is a schematic block diagram of the structure of a computer device provided in an embodiment of this application. The computer device includes a processor, a memory, and a network interface connected via a device bus, wherein the memory may include a storage medium and internal memory.

[0108] The storage medium may store operating devices and computer programs. The computer program includes program instructions that, when executed, cause the processor to perform any through-hole filling electroplating method for printed circuit boards.

[0109] The processor provides computing and control capabilities, supporting the operation of the entire computer device.

[0110] Internal memory provides an environment for the execution of computer programs in non-volatile storage media. When executed by a processor, the computer program enables the processor to perform any through-hole filling electroplating method for printed circuit boards.

[0111] This network interface is used for network communication, such as sending assigned tasks. Those skilled in the art will understand that... Figure 3 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the terminal to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0112] It should be understood that the processor can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Among these, a general-purpose processor can be a microprocessor or any conventional processor.

[0113] In one embodiment, the processor is configured to run a computer program stored in memory to perform the following steps: Laser microvia processing is performed on the printed circuit board to form microvias; the adhesive is removed from the printed circuit board with microvias. After removing the adhesive, the printed circuit board is subjected to black hole treatment or direct electroplating treatment; the treated printed circuit board is filled with an acidic copper plating solution containing leveling agent, inhibitor and accelerator, which preferentially adsorbs and inhibits deposition at the hole opening under high current density, and accelerates deposition in the low current density area, i.e., inside the hole, to achieve void-free filling from the bottom of the hole to the hole opening. During the through-hole plating process, a multi-stage plating current parameter program is used for control. In the initial stage, a low current density is used for pre-plating inside the hole to ensure uniform coverage of the hole wall. After entering the main through-hole plating stage, a pulsed or periodic reverse current is used, and the current density is increased stepwise. The through-hole is quickly filled with a special acidic copper plating through-hole plating solution. At the end of the filling process, the parameters are adjusted to ensure uniform copper thickness on the hole surface and avoid dish-shaped pits or excessive depressions.

[0114] In some embodiments, the laser microvia processing of the printed circuit board to form microvias includes: using a computer-controlled laser drilling device to process and form microvias with a diameter of 50-150 micrometers and a depth-to-diameter ratio of ≥3:1 in a designated area of ​​the printed circuit board at a laser power of 5-20 watts, a pulse frequency of 10-50 kHz, and a drilling speed of 50-200 mm / s.

[0115] In some embodiments, the process of removing adhesive from a printed circuit board with micro-vias includes: conveying the printed circuit board to an automatic adhesive removal station, immersing it in a 5-15% sodium hydroxide solution, maintaining the solution temperature at 50-80 degrees Celsius using a temperature control system, having a mechanical transmission device drive the board to oscillate at a rate of 2-5 revolutions per minute, processing for 2-10 minutes, and automatically rinsing off any remaining adhesive solution by a spray system after the adhesive removal is completed.

[0116] In some embodiments, the black hole treatment or direct electroplating treatment of the printed circuit board after adhesive removal includes: if black hole treatment is performed, the board is immersed in a carbon paste solution via a horizontal conveyor belt; the carbon particle concentration of the carbon paste solution is 10-30 g / L; the board passes through the coating area at a speed of 1-5 m / min and is cured by an infrared drying line to form a conductive carbon layer; the infrared drying line corresponds to a temperature of 80-120 degrees Celsius; if direct electroplating treatment is performed, the board is immersed in a palladium activation solution and left to stand for 1-5 minutes to complete catalytic activation; the palladium activation solution corresponds to a palladium ion concentration of 0.1-1 g / L and a temperature of 20-50 degrees Celsius.

[0117] In some embodiments, the process of electroplating the treated printed circuit board with an acidic copper plating solution includes: loading the printed circuit board into an electroplating tank, maintaining the temperature of the acidic copper plating solution at 25-45 degrees Celsius and the pH value at 1.5-3.5 through a solution circulation system, wherein the concentration of the leveling agent is 0.1-1 g / L, the concentration of the inhibitor is 5-20 g / L and the concentration of the accelerator is 0.01-0.5 g / L, and the composition of the solution is monitored in real time by an online sensor and replenished by an automatic replenishment device according to a preset ratio.

[0118] In some embodiments, the initial stage uses a low current density for in-hole pre-plating to ensure uniform coverage of the hole wall. This includes controlling the initial output of the electroplating power supply to a DC current of 0.5-2 amperes / square decimeter for 5-15 minutes, and feeding back the current density to a preset control system in real time through a current density sensor. When the copper layer thickness of the hole wall reaches 0.5-1 micrometer, the main hole filling stage is automatically triggered.

[0119] In some embodiments, after entering the main hole-filling stage, pulsed or periodic reverse current is used, and the current density is increased stepwise to quickly fill the through holes using an acidic copper plating hole-filling solution. This includes: in pulsed current mode, the frequency is set to 10-1000 Hz and the duty cycle to 10%-50%, and the current density starts from 2 amps / dm², increasing stepwise by 0.5-2 amps / dm² every 5-10 minutes until it reaches 5-15 amps / dm²; in periodic reverse current mode, the switching cycle between forward and reverse current is controlled to be 10-30 seconds, the duration of reverse current is 1-5 seconds, and the intensity of reverse current is 20%-50% of the forward current. The switching cycle between forward and reverse current, the duration of reverse current, and the intensity of reverse current are switched by the electroplating power supply according to preset rules.

[0120] In some embodiments, adjusting parameters at the end of the filling process to ensure uniform copper thickness on the hole surface and avoid dish-shaped pits or excessive depressions includes: when the filling height in the hole reaches 80%-90% of the hole depth, the electroplating power supply automatically switches to DC mode, the current density drops to 1-3 amperes / square decimeter, and continues for 5-10 minutes. At the same time, the hole surface is scanned online using a laser thickness gauge. When the standard deviation of the copper layer thickness is detected to be ≤5%, the filling is considered complete.

[0121] In some embodiments, the method further includes: acquiring process data in real time through a multi-sensor array deployed on the electroplating line, inputting the data into a pre-trained machine learning model, wherein the machine learning model dynamically optimizes the multi-stage electroplating current parameter program based on historical filling quality data to form a closed-loop feedback control; the machine learning model is periodically trained iteratively with new production data to adapt to the via filling requirements of printed circuit boards with different apertures and board thicknesses; wherein the multi-sensor array includes a current sensor, a temperature sensor, a laser thickness gauge, and a chemical composition detector; and the historical filling quality data includes core filling rate, void ratio, and copper thickness uniformity.

[0122] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, causes the processor to perform the steps of the through-hole filling electroplating method for printed circuit boards as provided in any embodiment of this application.

[0123] The computer-readable storage medium may be an internal storage unit of the computer device described in the foregoing embodiments, such as the hard disk or memory of the computer device. The computer-readable storage medium may also be an external storage device of the computer device, such as a plug-in hard disk, SmartMedia Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the computer device.

[0124] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for electroplating through-holes in printed circuit boards, characterized in that, include: Laser microvia processing is performed on printed circuit boards to form microvias; Remove adhesive from printed circuit boards with micro-vias; After removing the adhesive, the printed circuit board is subjected to black hole treatment or direct electroplating treatment; the treated printed circuit board is filled with an acidic copper plating solution containing leveling agent, inhibitor and accelerator, which preferentially adsorbs and inhibits deposition at the hole opening under high current density, and accelerates deposition in the low current density area, i.e., inside the hole, to achieve void-free filling from the bottom of the hole to the hole opening. During the through-hole plating process, a multi-stage plating current parameter program is used for control. In the initial stage, a low current density is used for pre-plating inside the hole to ensure uniform coverage of the hole wall. After entering the main through-hole plating stage, a pulsed or periodic reverse current is used, and the current density is increased stepwise. The through-hole is quickly filled with a special acidic copper plating through-hole plating solution. At the end of the filling process, the parameters are adjusted to ensure uniform copper thickness on the hole surface and avoid dish-shaped pits or excessive depressions.

2. The method according to claim 1, characterized in that, The process of laser microvia processing on the printed circuit board to form microvias includes: Using computer-controlled laser drilling equipment, micro-vias with diameters of 50-150 micrometers and depth-to-diameter ratios of ≥3:1 are formed in designated areas of printed circuit boards with a laser power of 5-20 watts, a pulse frequency of 10-50 kHz, and a drilling speed of 50-200 mm / s.

3. The method according to claim 1, characterized in that, The process of removing adhesive from printed circuit boards with microvias includes: The printed circuit board is conveyed to the automatic desmearing station and immersed in a 5-15% sodium hydroxide solution. The solution temperature is maintained at 50-80 degrees Celsius by a temperature control system. The mechanical transmission device drives the board to swing at a speed of 2-5 revolutions per minute. The processing time is 2-10 minutes. After the desmearing is completed, the residual solution is automatically rinsed off by a spray system.

4. The method according to claim 1, characterized in that, The process of performing black hole treatment or direct electroplating on the printed circuit board after adhesive removal includes: If black hole treatment is to be performed, the plate is immersed in carbon paste solution via a horizontal conveyor belt; the carbon particle concentration of the carbon paste solution is 10-30 g / L. Passing through the coating area at a speed of 1-5 meters per minute, the conductive carbon layer is cured by an infrared drying line; the infrared drying line corresponds to a temperature of 80-120 degrees Celsius. If direct electroplating is to be performed, the plate is immersed in palladium activation solution and left to stand for 1-5 minutes to complete catalytic activation; the palladium activation solution corresponds to a palladium ion concentration of 0.1-1 g / L and a temperature of 20-50 degrees Celsius.

5. The method according to claim 1, characterized in that, The process of electroplating the treated printed circuit board with an acidic copper plating solution includes: The printed circuit board is loaded into the electroplating tank. The acidic copper plating solution is maintained at a temperature of 25-45 degrees Celsius and a pH value of 1.5-3.5 through a chemical circulation system. The concentration of leveling agent is 0.1-1 g / L, the concentration of inhibitor is 5-20 g / L, and the concentration of accelerator is 0.01-0.5 g / L. The chemical composition is monitored in real time by online sensors and replenished by an automatic replenishment device according to a preset ratio.

6. The method according to claim 1, characterized in that, The initial stage employs low current density for in-hole pre-plating to ensure uniform coverage of the hole walls, including: The electroplating power supply is initially output with a DC current of 0.5-2 amperes per square decimeter for 5-15 minutes. The current density sensor provides real-time feedback to the preset control system. When the copper layer thickness of the hole wall reaches 0.5-1 micrometer, the main hole filling stage is automatically triggered.

7. The method according to claim 6, characterized in that, After entering the main via-filling stage, pulsed or periodic reverse current is used, with the current density increased in stages, to quickly fill the through-holes using a special acidic copper plating via-filling solution, including: In pulsed current mode, set the frequency to 10-1000 Hz and the duty cycle to 10%-50%. Start the current density at 2 amps / dm² and increase it stepwise by 0.5-2 amps / dm² every 5-10 minutes until it reaches 5-15 amps / dm². In the periodic reverse current mode, the switching cycle between forward and reverse current is controlled to be 10-30 seconds, the duration of reverse current is 1-5 seconds, and the intensity of reverse current is 20%-50% of the forward current. The switching cycle between forward and reverse current, the duration of reverse current, and the intensity of reverse current are switched by the electroplating power supply according to preset rules.

8. The method according to claim 1, characterized in that, The adjustment of parameters at the end of the filling process to ensure uniform copper thickness on the hole surface and avoid dish-shaped pits or excessive depressions includes: When the filling height in the hole reaches 80%-90% of the hole depth, the electroplating power supply automatically switches to DC mode, and the current density drops to 1-3 amperes / square decimeter for 5-10 minutes. At the same time, the hole surface is scanned online by a laser thickness gauge. When the standard deviation of the copper layer thickness is detected to be ≤5%, the filling is considered complete.

9. The method according to claim 1, characterized in that, The method further includes: The process data is collected in real time by a multi-sensor array deployed on the electroplating line and input into a pre-trained machine learning model. The machine learning model dynamically optimizes the multi-stage electroplating current parameter program based on historical filling quality data to form a closed-loop feedback control. The machine learning model is periodically trained iteratively with new production data to adapt to the filling requirements of printed circuit boards with different apertures and board thicknesses. The multi-sensor array includes a current sensor, a temperature sensor, a laser thickness gauge, and a chemical composition detector; historical filling quality data includes core rate, void rate, and copper thickness uniformity.

10. A through-hole filling electroplating system for printed circuit boards, characterized in that, The method applied to any one of claims 1-9 includes: The through-hole forming unit is used to perform laser micro-through-hole processing on printed circuit boards to form micro-through-holes; and to perform adhesive removal processing on printed circuit boards with micro-through-holes. The electroplating unit is used to perform black hole treatment or direct electroplating on the printed circuit board after adhesive removal. The treated printed circuit board is filled with an acidic copper plating solution containing leveling agents, inhibitors and accelerators. Under high current density, it preferentially adsorbs and inhibits deposition at the hole opening, and accelerates deposition in the low current density area, i.e., inside the hole, to achieve void-free filling from the bottom of the hole to the hole opening. The program control unit is used to control the electroplating current parameters in a multi-stage process during the hole filling electroplating process. In the initial stage, a low current density is used for pre-plating inside the hole to ensure uniform coverage of the hole wall. After entering the main hole filling stage, a pulsed or periodic reverse current is used, and the current density is increased stepwise. The through hole is quickly filled with a special acidic copper plating solution for hole filling. At the end of the filling stage, the parameters are adjusted to ensure uniform copper thickness on the hole surface and avoid dish-shaped pits or excessive depressions.

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