Via fill plating method and system for printed circuit boards

Abstract

The present application relates to the field of integrated circuit manufacturing, especially in the field of manufacturing technology of special-purpose equipment for semiconductor devices such as special-purpose photolithography machine and etching machine, and provides a via hole filling electroplating method and system for printed circuit board. The method comprises the following steps: performing laser micro-via hole processing on the printed circuit board; performing glue removal processing on the printed circuit board with micro-via holes; performing black hole processing or direct electroplating processing on the printed circuit board after glue removal; filling hole electroplating on the processed printed circuit board by using acid copper plating hole filling special chemical solution; in the process of hole filling electroplating, a multi-stage electroplating current parameter program is used, a low current density is used for pre-plating in the hole in the initial stage to ensure uniform coverage of the hole wall, after entering the main hole filling stage, pulse or periodic reverse current is used, and the current density is increased in steps, the acid copper plating hole filling special chemical solution is used to fill the via hole, and the parameters are adjusted at the end of the filling period to ensure uniform copper thickness of the hole surface, and avoid the occurrence of dish-shaped pits or excessive depression.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of integrated circuit manufacturing, especially in the field of manufacturing special-purpose lithography machines, etching machines and other semiconductor device manufacturing equipment, and relates to a via hole filling and electroplating method and system for printed circuit boards. BACKGROUND

[0002] In the field of integrated circuit manufacturing, especially in the field of manufacturing special-purpose lithography machines, etching machines and other semiconductor device manufacturing equipment, the traditional via hole filling process generally uses laser blind hole technology, and the process flow is "laser blind hole - glue removal - micro-etching - blind hole AOI - PTH - via hole filling and electroplating". This process has significant defects: on the one hand, the process is long and the cost is high, and the laser drilling precision and the cleanliness of the bottom of the blind hole are required to be extremely high, which easily leads to partial layering of the bottom of the blind hole due to residue of glue or uneven laser energy, affecting reliability; on the other hand, due to uneven current distribution and insufficient filling capacity of the chemical solution, defects such as "core" and "hollow" often occur, which requires repeated rework.

[0003] Therefore, there is an urgent need for a method to solve at least one of the above problems. SUMMARY

[0004] The present application provides a via hole filling and electroplating method and system for printed circuit boards, aiming to solve the problem in the prior art that the improvement of blind hole filling mainly focuses on optimizing the precision of laser equipment or adjusting a single electroplating parameter (such as fixed current density), but does not break through the limitations of the blind hole structure itself, and does not involve the coordinated scheme of via hole structure and special chemical solution and dynamic current control. For example, the traditional via hole filling chemical solution lacks directional adsorption ability for the aspect ratio of the via hole, and cannot achieve uniform filling from the bottom of the hole to the hole opening; the fixed current mode is difficult to balance the hole wall coverage and filling efficiency, and is prone to problems such as excessive deposition on the surface or insufficient filling in the hole.

[0005] In a first aspect, an embodiment of the present application provides a via hole filling and electroplating method for a printed circuit board, the method comprising:

[0006] Performing laser micro-via hole processing on the printed circuit board to form a micro-via hole; and performing glue removal processing on the printed circuit board with the micro-via hole;

[0007] Performing black hole processing or direct electroplating processing on the printed circuit board after glue removal; and performing via hole filling and electroplating on the processed printed circuit board using an acid copper plating via hole filling special chemical solution, the acid copper plating via hole filling special chemical solution containing a leveling agent, an inhibitor and an accelerator, so as to preferentially adsorb and inhibit deposition at the hole opening under high current density, accelerate deposition in the hole under low current density, and realize non-hollow filling from the bottom of the hole to the hole opening;

[0008] In the process of filling hole plating, a multi-stage plating current parameter program is used for control. A low current density is used in the initial stage for pre-plating in the hole to ensure uniform coverage of the hole wall. After entering the main filling hole stage, pulse or periodic reverse current is used, and the current density is increased in steps. Acid copper plating filling hole special solution is used to quickly fill the through hole. At the end of the filling period, the parameters are adjusted to ensure uniform copper thickness on the hole surface, avoiding the appearance of dish-shaped pits or excessive depression.

[0009] In some embodiments, the laser microvia processing of the printed circuit board to form a microvia includes: using a computer to control a laser drilling device to process a microvia with a diameter of 50-150 microns and a depth-diameter ratio of ≥3:1 in a specified 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.

[0010] In some embodiments, the desmearing treatment of the printed circuit board with a microvia includes: conveying the printed circuit board to an automatic desmearing station, immersing it in a sodium hydroxide solution with a concentration of 5-15%, maintaining the solution temperature at 50-80 degrees Celsius through a temperature control system, rotating the board at a speed of 2-5 revolutions per minute through a mechanical transmission device, and processing for 2-10 minutes. After desmearing, the residual solution is automatically flushed by a spraying system.

[0011] In some embodiments, the black hole treatment or direct plating treatment of the desmeared printed circuit board includes: if black hole treatment is performed, immersing the board in a carbon slurry solution through a horizontal conveyor belt; the carbon slurry solution has a carbon particle concentration of 10-30 grams per liter; passing through the coating area at a speed of 1-5 meters per minute to form a conductive carbon layer through an infrared drying line; the infrared drying line corresponds to a temperature of 80-120 degrees Celsius; if direct plating treatment is performed, immersing the board in a palladium activation solution and standing for 1-5 minutes to complete catalytic activation; the palladium activation solution has a palladium ion concentration of 0.1-1 gram per liter and a temperature of 20-50 degrees Celsius.

[0012] In some embodiments, the acid copper plating filling hole special solution is used for filling hole plating of the treated printed circuit board, including: loading the printed circuit board into a plating tank, maintaining the acid copper plating solution temperature at 25-45 degrees Celsius and the pH value at 1.5-3.5 through a solution circulation system, wherein the leveling agent concentration is 0.1-1 gram per liter, the inhibitor concentration is 5-20 grams per liter, and the accelerator concentration is 0.01-0.5 grams per liter. The solution composition is monitored in real time by an online sensor, and is supplemented by an automatic liquid supplementing device according to a preset ratio.

[0013] In some embodiments, the initial stage adopts low current density for in-hole pre-plating to ensure uniform coverage of the hole wall, including: controlling the initial output of the electroplating power supply to be 0.5-2 ampere per square decimeter of direct current, lasting for 5-15 minutes, and feeding back to the preset control system in real time through the current density sensor, and when the detected value of the copper layer thickness of the hole wall reaches 0.5-1 microns, automatically triggering the main hole filling stage.

[0014] In some embodiments, after entering the main hole filling stage, pulse or periodic reverse current is adopted, and the current density is increased in steps, and the through hole is filled quickly by using acidic copper plating hole filling special solution, including: in the pulse current mode, the frequency is set to 10-1000 hertz and the duty cycle is set to 10%-50%, the current density starts from 2 ampere per square decimeter, and increases by 0.5-2 ampere per square decimeter every 5-10 minutes in steps until reaching 5-15 ampere per square decimeter; in the periodic reverse current mode, the switching period of the forward current and the reverse current is controlled to be 10-30 seconds, the reverse current duration is 1-5 seconds, and the reverse current intensity is 20%-50% of the forward current, and the switching period of the forward current and the reverse current, the reverse current duration and the reverse current intensity are switched by the electroplating power supply according to the preset rules.

[0015] In some embodiments, at the end of the filling stage, the parameters are adjusted to ensure uniform copper thickness of the hole surface and avoid the occurrence of dish-shaped pits or excessive depression, including: when the filling height in the hole reaches 80%-90% of the hole depth, the electroplating power supply is automatically switched to the direct current mode, the current density is reduced to 1-3 ampere per square decimeter, and lasts for 5-10 minutes, and at the same time, the hole surface is scanned online by the laser thickness gauge, and when the standard deviation of the copper layer thickness is ≤5%, it is determined that the filling is completed.

[0016] In some embodiments, the method further includes: collecting process data in real time by a multi-sensor array deployed in the electroplating line, inputting a pre-trained machine learning model, dynamically optimizing the multi-stage electroplating current parameter program according to historical filling quality data by the machine learning model, and forming a closed-loop feedback control; the machine learning model is iteratively trained periodically by new production data to adapt to the through hole filling requirements of printed circuit boards with different hole diameters and board thicknesses; wherein the multi-sensor array includes current sensors, temperature sensors, laser thickness gauges and solution composition detectors; the historical filling quality data includes core rate, void rate and copper thickness uniformity.

[0017] In a second aspect, the present application provides a through hole filling electroplating system for printed circuit boards, which is applied to the method provided in any of the embodiments of the present application, and the system includes:

[0018] A through hole forming unit is configured to perform laser micro-via processing on the printed circuit board to form micro-vias, and perform glue removal processing on the printed circuit board with micro-vias.

[0019] The electroplating processing unit is used for black hole processing or direct electroplating processing on the printed circuit board after desmear; the acid copper plating hole filling special solution is used for hole filling electroplating on the processed printed circuit board, and the acid copper plating hole filling special solution contains a leveling agent, an inhibitor and an accelerator, so that the inhibitor is preferentially adsorbed to inhibit deposition at the hole opening under high current density, and the deposition is accelerated in the hole under low current density, thereby realizing non-cavity filling from the hole bottom to the hole opening.

[0020] The program control unit is used for controlling the filling electroplating process by using a multi-stage electroplating current parameter program, a low current density is used for pre-plating in the hole in the initial stage to ensure uniform hole wall coverage, and after entering the main hole filling stage, pulse or periodic reverse current is used, and the current density is increased in steps, the acid copper plating hole filling special solution is used for rapid filling of the through hole, and the parameters are adjusted at the end of the filling period to ensure uniform copper thickness of the hole surface, thereby avoiding the occurrence of dish-shaped pits or excessive depression.

[0021] The application adopts a short process of "laser micro via hole-desmear-black hole-hole filling electroplating", omits the links of micro-etching, AOI detection and PTH in the traditional blind hole process, shortens the process time by 30%-50%, reduces the material and equipment loss cost. The risk of blind hole bottom partial layer is completely avoided, the through hole structure combines the directional adsorption characteristics of the special solution, realizes non-cavity filling from the hole bottom to the hole opening, and the filling yield is improved. The multi-stage current control (low current pre-plating + pulse / reverse current main filling + end parameter adjustment) ensures the balance of hole wall uniform coverage, filling speed and surface flatness, and avoids defects such as "dish-shaped pit" and "excessive depression". Through the synergistic effect of the leveling agent, inhibitor and accelerator of the acid copper plating solution, the micro via hole (diameter 50-150 microns) with a depth-diameter ratio of ≥3:1 can be adapted, and the limitation of the traditional process on the hole depth-diameter ratio is broken through.

[0022] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the application. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creating laborious work.

[0024] Figure 1 is a step schematic flow chart of a through hole hole filling electroplating method for a printed circuit board provided by an embodiment of the application;

[0025] Figure 2 is a structural schematic block diagram of a through hole hole filling electroplating system for a printed circuit board provided by an embodiment of the application;

[0026] Figure 3 is a structural schematic block diagram of a computer device provided by an embodiment of the present application.

[0027] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and are not intended to limit the present application. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0029] The flowcharts shown in the drawings are only exemplary and are not necessarily required to include all the contents and operations / steps, and are not necessarily required to be executed in the described order. For example, some operations / steps can be decomposed, combined or partially combined, and thus the actual execution order can be changed according to the actual situation.

[0030] It should be understood that, in order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, the terms “first”, “second”, etc. are used to distinguish the same items or similar items with basically the same functions and effects. Those skilled in the art can understand that the terms “first”, “second”, etc. do not limit the quantity and execution order, and the terms “first”, “second”, etc. also do not necessarily mean different.

[0031] It should be understood that the terms used in the present application specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the present application specification and the appended claims, unless otherwise clearly indicated by the context, the singular forms “a”, “an” and “the” are intended to include the plural forms.

[0032] It should also be understood that the term “and / or” used in the present application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0033] In the field of printed circuit board (PCB) manufacturing, the traditional hole filling process generally uses laser blind hole technology, and its process flow is "laser blind hole - degumming - micro etching - blind hole AOI - PTH - hole filling plating". This process has significant defects: on the one hand, the process is long and costly, and it requires high precision of laser drilling and high cleanliness of the bottom of the blind hole, which is prone to cause the bottom of the blind hole to be partially layered due to residue or uneven laser energy, affecting reliability; on the other hand, during the hole filling process, due to uneven current distribution and insufficient plating solution filling capacity, defects such as "core" and "hollow" often occur, which requires repeated rework.

[0034] In the prior art, the improvement of blind hole filling mainly focuses on optimizing the precision of laser equipment or adjusting a single plating parameter (such as fixed current density), but it does not break through the limitations of the blind hole structure itself and does not involve the coordinated scheme of through-hole structure, special plating solution and dynamic current control. For example, the traditional hole filling plating solution lacks directional adsorption capacity for the aspect ratio of the through hole, and cannot achieve uniform filling from the bottom to the opening of the hole; the fixed current mode is difficult to balance the hole wall coverage and filling efficiency, which is prone to cause excessive deposition on the surface or insufficient filling in the hole.

[0035] To solve the above problems, please refer to Figure 1 , the embodiment of the present application provides a through-hole filling plating method for a printed circuit board, which is applied to a computer device. The computer device can be deployed on a single server or a server cluster. It can also be deployed on a handheld terminal, a notebook computer, a wearable device, or a robot, etc.

[0036] The through-hole filling plating method for a printed circuit board provided includes steps S101 to S103. The details are as follows:

[0037] Step S101. Laser micro-hole processing is performed on the printed circuit board to form a micro-hole; and the printed circuit board with the micro-hole is subjected to degumming treatment.

[0038] Specifically, the laser micro-hole processing processes micron-level holes (micro-holes) on the printed circuit board (PCB) through high-precision laser equipment, solves the limitations of traditional mechanical drilling in aspect ratio (such as ≥10:1) and hole diameter precision (such as ≤50μm), and ensures that the hole wall perpendicularity and surface roughness meet the plating requirements.

[0039] The degumming treatment removes the resin carbonized residue (residue) generated during laser processing, avoids residue remaining to cause insufficient adhesion of the hole wall and the plating layer or internal insulation, and affects the subsequent conductive performance and hole filling quality.

[0040] Laser processing uses ultraviolet laser (wavelength 355 nm) or femtosecond laser equipment, equipped with CCD visual positioning system, positioning accuracy ≤ ± 5 μm. According to the design requirements, adjust the laser energy (50-100 mJ), pulse frequency (20-100 kHz) and scanning speed (50-200 mm / s), process the microvia with aperture 10-100 μm, depth-diameter ratio 5:1 to 15:1.

[0041] Debinding treatment uses potassium permanganate solution (concentration 8-15 g / L, temperature 60-80 °C, pH 12-14) for chemical debinding, or plasma (oxygen plasma, power 100-300 W, processing time 5-15 min) for physical debinding. After debinding, ultrasonic cleaning with deionized water (water temperature 40-60 °C, time 3-5 min) is used to ensure that there is no residual glue and chemical agent residue on the hole wall.

[0042] Step S102. Black hole treatment or direct electroplating treatment is performed on the debound printed circuit board; acid copper plating hole filling special solution containing leveling agent, inhibitor and accelerator is used for hole filling electroplating of the treated printed circuit board, so as to preferentially adsorb and inhibit deposition at the hole opening under high current density, accelerate deposition in the hole under low current density, and realize non-cavity filling from the hole bottom to the hole opening.

[0043] Specifically, black hole treatment (optional): for non-conductive hole wall (such as dielectric layer), a thin conductive layer is formed by conductive treatment (such as carbon particle adhesion) to replace the traditional chemical copper deposition process, simplify the process and improve the conductivity of the hole wall.

[0044] The acid copper plating hole filling electroplating uses special solution (containing leveling agent, inhibitor and accelerator) to realize "bottom priority filling" by using electrochemical adsorption characteristics: the inhibitor (such as sulfur-containing organic compound) preferentially adsorbs at the hole opening under high current density to inhibit copper deposition; the accelerator (such as chloride ion, organic amine) promotes the reduction of copper ions in the hole under low current density to realize non-cavity filling from the hole bottom to the hole opening; the leveling agent (such as polydisulfide compound) adjusts the surface flatness of the plating layer to reduce the surface roughness.

[0045] The corresponding process of black hole treatment: hole wall activation (palladium activation solution, concentration 0.5-1 g / L, temperature 30-40 °C, time 1-3 min) → carbon slurry coating (carbon particle size 0.1-0.5 μm, solid content 5-10%, uniformly attached by vacuum adsorption or horizontal coating machine) → heat curing (temperature 80-120 °C, time 10-20 min), forming a conductive layer with a thickness of 0.1-0.3 μm.

[0046] The corresponding plating solution for acidic copper plating for via filling is: copper sulfate 80-120 g / L, sulfuric acid 150-200 g / L, chloride ion 50-80 ppm; leveler 0.1-0.5 mL / L, suppressor 5-10 mL / L, accelerator 1-3 mL / L; pH 1.0-1.8, temperature 25-35°C, solution circulation filtration (filter core precision ≤1 μm).

[0047] The plating equipment is equipped with an anode titanium basket (containing phosphor copper balls, phosphor content 0.03-0.07%) and a cathode moving device (speed 5-10 m / min) through a vertical continuous plating line (VCP line) or a horizontal plating line.

[0048] Step S103. In the via filling plating process, a multi-stage plating current parameter program is used for control. A low current density is used in the initial stage for pre-plating in the hole to ensure uniform coverage of the hole wall. After entering the main via filling stage, pulse or periodic reverse current is used, and the current density is increased in steps. The special plating solution for acidic copper via filling is used to quickly fill the via. The parameters are adjusted at the end of the filling period to ensure uniform copper thickness on the hole surface, avoiding the occurrence of dish-shaped pits or excessive depression.

[0049] Specifically, by dynamically adjusting the current density and waveform in stages, the uniformity of hole wall coverage and the filling efficiency are balanced, and the surface over-deposition or hole cavity caused by the traditional fixed current mode is avoided: initial stage (pre-plating): low current density ensures no plating leakage and uniform coverage of the hole wall; main via filling stage: pulse / periodic reverse current combined with stepwise current increase, which uses the "super filling" ability of the plating solution to accelerate the filling in the hole and suppress the copper tumor at the hole edge; end of filling: adjust the parameters to make the copper thickness on the hole surface uniform, avoiding dish-shaped pits (depression depth ≤5 μm) or excessive depression.

[0050] The initial stage (pre-plating) includes: current mode: direct current (DC), current density 1-3 ASD (ampere / square decimeter); time: 5-10 min, ensuring that the hole wall plating layer thickness is ≥0.5 μm, and the coverage is uniform without pores.

[0051] The main filling stage includes: current mode: pulse current (PC) or periodic reverse current (PRC): pulse current: frequency 50-200 Hz, duty cycle 10-30%, forward current density from 5 ASD stepwise to 15 ASD (increased 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 the aperture deposition by using the "tip dissolution" effect of pulse / reverse current, and to increase the copper ion deposition rate in the hole by stepwise current increase, filling rate ≥2 μm / min. The filling end stage includes: current mode: direct current, current density reduced to 3-5 ASD; time: 5-10 min, to ensure that the surface copper thickness uniformity is ≤±5%, and the hole filling is full (no cavity detected by slicing, filling rate ≥99%).

[0052] In some embodiments, the laser micro-via processing of the printed circuit board to form a micro-via includes: using a computer to control a laser drilling device to process a micro-via with a diameter of 50-150 microns and a depth-diameter ratio ≥3:1 in a specified 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.

[0053] The computer precisely controls the laser drilling device to process high-precision micro-vias in a specified area of the printed circuit board, ensuring that the diameter and depth-diameter ratio of the hole meet the requirements of the hole filling process.

[0054] The device control uses a computer program to set the laser drilling path and parameters, and links the motion axes (such as X / Y axes) of the laser device to achieve micron-level positioning.

[0055] Process parameters: laser power: 5-20 watts (adjust energy density to avoid carbonization of hole wall); pulse frequency: 10-50 kHz (control drilling speed and heat-affected zone of hole wall); drilling speed: 50-200 mm / s (match material thickness and hole diameter requirements); processing target: form a micro-via with a diameter of 50-150 microns and a depth-diameter ratio ≥3:1, hole wall perpendicularity error ≤5°, surface roughness Ra ≤2.5 μm.

[0056] In some embodiments, the glue removal treatment of the printed circuit board with a micro-via includes: conveying the printed circuit board to an automatic glue removal station, immersing it in a sodium hydroxide solution with a concentration of 5-15%, maintaining the solution temperature at 50-80 degrees Celsius through a temperature control system, driving the board to oscillate at a speed of 2-5 revolutions per minute through a mechanical transmission device, processing time 2-10 minutes, and automatically rinsing the residual chemical solution after glue removal by a spraying system.

[0057] The printed circuit board after laser drilling is chemically degreased by sodium hydroxide solution, and the degreasing efficiency and uniformity are improved by mechanical swinging and temperature control system.

[0058] The printed circuit board is sent into the degreasing tank by the conveyor belt, and the tank body is equipped with a temperature control system (accuracy ±2℃) and a mechanical swinging device.

[0059] Process parameters: sodium hydroxide concentration: 5-15% (adjust the corrosiveness for different resin materials); solution temperature: 50-80℃ (increase the chemical reaction activity); swinging rate: 2-5 revolutions / minute (enhance the solution convection and flush the hole wall residue); processing time: 2-10 minutes (adjust according to the hole depth and residue thickness); post-processing: after degreasing, through multi-stage spraying (water pressure ≥0.5MPa) and ultrasonic cleaning (frequency 40kHz), to ensure no drug residue.

[0060] In some embodiments, the degreased printed circuit board is treated by black hole or direct electroplating, including: if black hole treatment is performed, the board body is immersed in carbon slurry solution by horizontal conveyor belt; the carbon particle concentration of the carbon slurry solution is 10-30 grams / liter; pass through the coating area at a speed of 1-5 meters / minute, and form a conductive carbon layer by infrared drying line curing; the infrared drying line corresponds to a temperature of 80-120 degrees Celsius; if direct electroplating treatment is performed, the board body is immersed in palladium activation solution and placed for 1-5 minutes to complete catalytic activation; the palladium activation solution corresponds to a palladium ion concentration of 0.1-1 gram / liter and a temperature of 20-50 degrees Celsius.

[0061] According to the conductivity of the hole wall, black hole treatment or direct electroplating treatment is selected, black hole treatment forms a conductive layer by carbon slurry coating, and direct electroplating deposits metal by palladium activation solution catalysis.

[0062] The black hole treatment path includes: carbon slurry solution: carbon particle concentration 10-30 grams / liter (particle size 0.1-0.5μm, to ensure conductivity), immersed in the coating tank by horizontal conveyor belt at a speed of 1-5 meters / minute, to form a carbon layer with a thickness of 0.2-0.5μm; curing process: infrared drying line temperature 80-120℃, time 5-10 minutes, to make the carbon particles firmly adhere to the hole wall.

[0063] The direct electroplating path includes: palladium activation solution: palladium ion concentration 0.1-1 gram / liter (catalyze copper ion reduction), temperature 20-50℃, stand for 1-5 minutes, to make the hole wall adsorb catalytic active sites.

[0064] In some embodiments, the filling hole electroplating of the printed circuit board after treatment with the acidic copper plating hole filling special 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 by a solution circulating system, wherein the leveling agent concentration is 0.1-1 g / L, the inhibitor concentration is 5-20 g / L, and the accelerator concentration is 0.01-0.5 g / L, the solution composition is monitored in real time by an online sensor, and the automatic liquid supplementing device supplements the preset proportion.

[0065] The electrochemical characteristics of the acidic copper plating special solution are utilized to maintain the stability of the solution composition through the circulating system and online monitoring to realize directional filling.

[0066] The solution composition and control include: basic components: copper sulfate 80-120 g / L, sulfuric acid 150-200 g / L, chloride ion 50-80 ppm; additive concentration: leveling agent 0.1-1 g / L (such as polyether compounds), inhibitor 5-20 g / L (such as sulfur-containing organic matter), accelerator 0.01-0.5 g / L (such as ethylenediamine); environmental control: temperature 25-45°C (adjusted by refrigeration / heating unit), pH 1.5-3.5 (adjusted online by sulfuric acid / sodium hydroxide); circulating system: the solution is circulated through a filter core with a filtering precision of ≤1 μm (flow rate 10-20 m 3 / h), the composition is monitored in real time by an online sensor (such as pH meter, conductivity meter), and the automatic liquid supplementing device supplements the consumed reagents according to the preset proportion.

[0067] In some embodiments, the starting stage adopts low current density for in-hole pre-plating to ensure uniform coverage of the hole wall, including: controlling the initial output of the electroplating power source to be 0.5-2 ampere per square decimeter of direct current, lasting for 5-15 minutes, and feeding back to the preset control system in real time through the current density sensor, and automatically triggering the main hole filling stage when the hole wall copper layer thickness detection value reaches 0.5-1 microns.

[0068] The starting stage of electroplating adopts low current density direct current pre-plating, and the current density sensor and thickness detection realize automatic stage switching, ensuring full coverage of the hole wall.

[0069] The pre-plating control includes: current mode: direct current (DC), initial current density 0.5-2 ampere per square decimeter (ASD), avoiding high current leading to preferential deposition at the hole opening; duration: 5-15 minutes, during which the control system is fed back in real time through the current density sensor (accuracy ±0.1 ASD); switching condition: when the hole wall copper layer thickness (measured by coulomb meter or X-ray thickness gauge) reaches 0.5-1 microns, the main hole filling stage is automatically triggered.

[0070] In some embodiments, after the main hole filling stage, pulse or periodic reverse current is used, and the current density is increased in steps, and the through hole is quickly filled with acid copper plating hole filling special solution, including: in pulse current mode, the frequency is set to 10-1000 Hz and the duty cycle is 10%-50%, the current density starts from 2 A / dm2, and increases by 0.5-2 A / dm2 every 5-10 minutes, until it reaches 5-15 A / dm2; in periodic reverse current mode, the forward current and reverse current switching period is controlled to be 10-30 seconds, the reverse current duration is 1-5 seconds, and the reverse current intensity is 20%-50% of the forward current, and the forward current and reverse current switching period, reverse current duration and reverse current intensity are switched by the electroplating power supply according to the preset rules.

[0071] The main hole filling stage uses pulse or periodic reverse current combined with step-up current to inhibit orifice deposition and accelerate hole filling by electrochemical effect.

[0072] The pulse current mode includes: frequency: 10-1000 Hz (high frequency inhibits tip effect), duty cycle 10%-50% (adjusts average current density); current density: starts from 2 ASD, increases by 0.5-2 ASD every 5-10 minutes, until 5-15 ASD (step-up current matches solution adsorption characteristics); periodic reverse current (PRC) mode: switching period: 10-30 seconds, reverse current duration: 1-5 seconds, intensity: 20%-50% of the forward current (dissolves excess copper at the orifice, balances the deposition rate inside and outside the hole); equipment support: electroplating power supply has multi-waveform output function (such as pulse, PRC), parameters are automatically switched by preset program.

[0073] In some embodiments, the parameters are adjusted at the end of the filling period to ensure uniform copper thickness on the hole surface and avoid the appearance of dish-shaped pits or excessive depression, including: when the hole filling height reaches 80%-90% of the hole depth, the electroplating power supply automatically switches to direct current mode, the current density is reduced to 1-3 A / dm2, and lasts for 5-10 minutes, while the hole surface is scanned online by a laser thickness gauge, and when the copper layer thickness standard deviation is ≤5%, it is determined that the filling is complete.

[0074] At the end of the filling period, the current density is reduced and switched to direct current mode, and the copper thickness uniformity is monitored online by a laser thickness gauge to ensure the flatness of the hole surface.

[0075] The stage switching condition is triggered at the end of the period when the hole filling height reaches 80%-90% as determined by real-time imaging or coulomb calculation;

[0076] Process parameters: current mode: direct current, current density reduced to 1-3 ASD (reducing the rate of surface deposition); duration: 5-10 minutes, during which the laser thickness gauge (accuracy ± 1 μm) performs grid scanning on the hole surface; judgment standard: when the standard deviation of copper thickness in the detection area is ≤5%, it is determined that the filling is completed, avoiding dish-shaped pits (recess depth > 5 μm) or excessive recess.

[0077] In some embodiments, the method further comprises: collecting process data in real time by a multi-sensor array deployed in the electroplating line, inputting a pre-trained machine learning model, dynamically optimizing a multi-stage electroplating current parameter program according to historical filling quality data, and forming a closed-loop feedback control; the machine learning model is iteratively trained periodically by new production data to adapt to the filling hole requirements of printed circuit boards with different hole diameters and board thicknesses; wherein the multi-sensor array includes current sensors, temperature sensors, laser thickness gauges, and chemical composition detectors; the historical filling quality data includes core rate, void rate, and copper thickness uniformity.

[0078] By introducing industrial Internet of Things and machine learning technology, real-time data collection by multi-sensor, dynamic optimization of electroplating parameters by closed-loop feedback system, and improvement of process adaptability.

[0079] The data acquisition layer includes: sensor array: current sensor (monitoring real-time current density), temperature sensor (chemical solution temperature), laser thickness gauge (copper layer thickness), and chemical composition detector (ion concentration); data frequency: collect ≥10 times per second and store to edge computing node.

[0080] The machine learning model includes: input features: hole diameter, board thickness, chemical composition, current parameter, temperature; output target: optimized multi-stage current parameter (such as stage length, current density, waveform); training mechanism: iteratively model periodically using new production data (including quality indicators such as core rate, void rate, and copper thickness uniformity) to support adaptive adjustment of different hole diameters (10-150 μm) and board thicknesses (0.5-3 mm). Closed-loop control: model output parameters are synchronized in real time to the electroplating power supply, forming a dynamic closed loop of “data acquisition-model optimization-parameter adjustment”, and improving the filling hole yield (target ≥99%).

[0081] In some embodiments, to solve the problem of additive fluctuation caused by traditional chemical solution replenishment relying on “post-detection”, through multi-sensor data fusion + machine learning prediction model, the consumption rate of additives (leveling agent, inhibitor, accelerator) is predicted in real time, the replenishment amount is adjusted in advance, the chemical composition is accurately maintained, and the filling defects (such as voids, copper tumors, and surface roughness) caused by additive decay are avoided.

[0082] The data acquisition layer collects real-time process data (sampling frequency ≥ 1 Hz) by deploying online high-performance liquid chromatography (HPLC) to detect additive concentration (precision ± 0.01 g / L), temperature sensors (± 1 °C), current sensors (± 0.1 ASD), and chemical solution flow sensors (± 0.1 m³ / h).

[0083] The historical filling quality data (such as void ratio and copper thickness uniformity) are associated to 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%).

[0084] The model training uses "temperature, current density, chemical solution flow, and initial additive concentration" as input features and "additive consumption rate (concentration decrease per unit time, such as g / L·min)" as output labels to train a long short-term memory network (LSTM) model (good at time series prediction). The "unqualified" samples are used to optimize the model to ensure that it can issue an early warning when the predicted consumption rate exceeds the "qualified threshold".

[0085] The dynamic replenishment logic receives real-time process data from the model to predict the additive consumption rate in the next 5-10 minutes. Based on the prediction, the replenishment amount is calculated (formula: replenishment amount = consumption rate × time × plating tank volume × additive purity), and the pump speed of the automatic replenishment device is adjusted according to the preset ratio (e.g., leveling agent: inhibitor: accelerator = 1:5:0.1). After replenishment, HPLC is used to verify whether the composition has 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 not, the fine adjustment is triggered again.

[0086] Compared with traditional "after-replenishment", the additive concentration fluctuation range is reduced from ± 15% to ± 5%, and the filling defect rate (voids and copper tumors) is reduced by more than 40%. The model is iteratively trained every 7 days with new production data to adapt to the attenuation characteristics of different batches of chemicals (e.g., accelerated consumption of accelerators due to high summer temperatures).

[0087] In some embodiments, to address the problem that traditional laser drilling "fixed parameters" cannot adapt to different plate thicknesses, hole diameters, and materials, machine learning + process knowledge are used to predict the optimal laser parameters (power, pulse frequency, drilling speed) in real time based on the plate thickness, hole diameter, and material type (e.g., 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.

[0088] Data collection collects historical laser drilling data: including board thickness (0.5-3mm), hole diameter (50-150pm), 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); mark the parameter boundary of "high-quality hole" (perpendicularity≤5°, Ra≤2.5pm) and "poor-quality hole" (perpendicularity>5° or Ra>2.5pm).

[0089] Model training takes "board thickness, hole diameter, material type" as input features, and "laser power, pulse frequency, drilling speed" as output labels, and trains a gradient boosting tree (GBDT) model (good at processing structured data and can output the importance ranking of parameters);

[0090] Combined with process knowledge (such as thicker plates requiring higher power to penetrate, and smaller hole diameters requiring higher frequency to reduce thermal effects), the model output is constrained (such as board thickness>2mm, power≥15W; hole diameter<80pm, frequency≥30kHz).

[0091] When a new batch of printed circuit boards enters the laser drilling station, the board thickness (through the edge profile), hole diameter (through the design file), and material type (through barcode scanning) are automatically identified by the CCD vision system; the above parameters are input into the model, and the optimal laser parameters are output (such as board thickness 2.5mm, hole diameter 80pm, FR4 material, output power 18W, frequency 35kHz, speed 120mm / s); the motion control card of the laser equipment receives the parameters, adjusts the laser generator (power), pulse generator (frequency), and servo motor (speed) in real time, and realizes adaptive processing of hole type.

[0092] In some embodiments, to solve the problem of high rework cost caused by "defect detection after filling" in traditional hole filling process, a multi-sensor data + deep learning model is used to predict the probability of filling defects (such as voids, copper tumors, and dish-shaped pits) in real time, and when the probability exceeds a threshold, the process parameters (such as current density, drug additive concentration) are actively adjusted to prevent problems from occurring.

[0093] Defect definition and data labeling define defect types through X-ray detection system (real-time scanning of hole filling) and laser thickness gauge (scanning surface copper thickness): void: hole filling area>5%; copper tumor: hole surface copper thickness>2 times surrounding (such as surrounding copper thickness 15pm, hole>30pm); dish-shaped pit: hole surface indentation depth>5pm; collect process data (current, temperature, drug concentration, copper thickness) and corresponding defect labels from multiple batches to build a training data set.

[0094] Model training takes "real-time current density (ASD), bath temperature (℃), inhibitor concentration (g / L), accelerator concentration (g / L), in-hole copper thickness growth rate (μm / min)" as input features, and "cavity probability, copper tumor probability, crater probability" as output labels to train a convolutional neural network (CNN) model (good at feature extraction of time series data);

[0095] The confusion matrix is used to optimize the model to ensure that the accuracy of defect prediction is ≥90% and the recall rate is ≥85% (i.e., as few defects as possible are missed).

[0096] The model receives process data in real time and outputs the probability of each defect (e.g., cavity probability = 85%, copper tumor probability = 10%, crater probability = 5%). When the probability of a certain defect exceeds a threshold value (e.g., cavity probability > 70%), an intervention strategy is triggered: if the cavity 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 hole filling stage (e.g., from 12 ASD to 10 ASD) to enhance the in-hole deposition rate; if the copper tumor 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 mouth; if the crater probability is high, reduce the current density at the end of filling (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 flatness.

[0097] In some embodiments, to address the poor synergy caused by the traditional process of "independent adjustment of current parameters and bath parameters" (e.g., high current density requires high inhibitor concentration, but the traditional method does not correlate), a multi-objective optimization algorithm + machine learning is used to find the optimal combination of "current parameters (pulse frequency, duty cycle)" and "bath parameters (inhibitor, accelerator concentration)", achieving a balance of maximum filling rate, minimum cavity rate, and optimal copper thickness uniformity.

[0098] The objective function definition includes: maximizing the filling rate (unit: μm / min): filling rate = in-hole copper thickness growth rate; minimizing the cavity rate (unit%): cavity rate = area of unfilled region in hole / hole area; minimizing the copper thickness uniformity (unit%): copper thickness uniformity = (maximum copper thickness - minimum copper thickness) / average copper thickness x 100%.

[0099] The variable definition includes: current parameters: pulse frequency (10-1000 Hz), duty cycle (10%-50%), forward current density (2-15 ASD); bath parameters: inhibitor concentration (5-20 g / L), accelerator concentration (0.01-0.5 g / L).

[0100] The optimization process includes: data collection: real-time collection of current parameters, chemical parameters, filling quality data (filling rate, void rate, copper thickness uniformity) through a multi-sensor array; model construction: mapping of the "variable → target function" relationship using a random forest (RF) model (e.g. current frequency ↑ → filling rate ↑, but void rate may ↑; suppressant concentration ↑ → void rate ↓, but filling rate may ↓); multi-objective optimization: using a non-dominated sorting genetic algorithm (NSGA-II) with the RF model as a surrogate model to search for Pareto optimal solutions of variables (i.e. solutions that cannot improve one objective without worsening another); solution selection: according to production requirements (e.g. prefer to improve efficiency by selecting solutions with high filling rate, or prefer to ensure quality by selecting solutions with low void rate), select the optimal combination from the Pareto frontier.

[0101] Real-time application logic: when a new batch of printed circuit boards enters the electroplating station, according to its hole diameter (50-150 μm) and board thickness (0.5-3 mm), select the corresponding optimal parameter combination from the pre-calculated Pareto solution library (e.g. for hole diameter 80 μm and board thickness 2 mm, select pulse frequency 200 Hz, duty cycle 25%, forward current 10 ASD, suppressant 12 g / L, accelerator 0.2 g / L); the electroplating power supply and automatic liquid supplementing device receive the parameters and adjust the current waveform and chemical composition in real time.

[0102] Compared with independent adjustment of parameters, the filling rate is increased by 40% (from 1.5 μm / min to 2.1 μm / min), the void rate is reduced by 50% (from 1.0% to 0.5%), and the copper thickness uniformity is improved by 30% (from ±8% to ±5.5%); the Pareto solution library is updated with new data every quarter to adapt to changes in the needs of different products.

[0103] In some embodiments, to solve the problem of "high trial and error cost" for traditional processes (e.g. adjusting parameters requires multiple experiments, time-consuming and material-consuming), a digital twin model of the printed circuit board hole filling process is constructed, the filling effect of different process parameters (laser, current, chemical) is predicted through virtual simulation, the optimal parameters are set in advance, and the number of actual trial and error is reduced.

[0104] The digital twin model construction includes: the physical layer collects geometric data (hole depth, hole diameter), process data (current, temperature), and quality data (copper thickness, void rate) of the actual hole filling process through multiple sensors (laser displacement sensor, current sensor, temperature sensor); the virtual layer uses finite element analysis (FEA) to construct a thermal-mechanical coupling model of laser drilling (simulates the melting and evaporation of laser energy on the hole wall), and uses computational fluid dynamics (CFD) to construct a mass transfer-electrochemical model of the electroplating process (simulates the diffusion and deposition of copper ions in the hole); data fusion inputs the data collected by the physical layer into the virtual layer to calibrate the model parameters (such as laser absorption coefficient, copper ion diffusion coefficient), and ensures that the error between the virtual model and the actual process is ≤10%.

[0105] The virtual trial and error logic inputs the design parameters (hole diameter, board thickness, number of layers) of the new batch of printed circuit boards into the digital twin model when they need to be filled with holes; the model simulates different process parameter combinations (such as laser power 15W and 20W, current density 10ASD and 12ASD, suppressant 10g / L and 15g / L), and outputs the virtual filling effect (filling rate, void rate, copper thickness uniformity); according to the virtual results, the optimal parameter combination is selected (such as simulation shows that when the power is 18W, the current is 10ASD, and the suppressant is 12g / L, the filling rate is 2.0μm / min, the void rate is 0.4%, and the copper thickness uniformity is ±5%).

[0106] The actual application sends the virtual optimal parameters to the laser drilling equipment and the electroplating equipment as the initial parameter settings; during the actual processing, the digital twin model is updated in real time through multi-sensor data, and if the deviation between the virtual and actual results exceeds 10% (such as the actual filling rate is 1.8μm / min and the virtual is 2.0μm / min), the model parameters are adjusted (such as correcting the copper ion diffusion coefficient) to improve the accuracy of subsequent simulation.

[0107] Compared with 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 the material loss is reduced by 70%; the digital twin model is calibrated every half year with new production data to ensure its adaptability.

[0108] Please refer to Figure 2 as shown, Figure 2 is a structural schematic diagram of a via hole filling electroplating system 200 for printed circuit boards provided by the embodiments of the present application. The via hole filling electroplating system 200 for printed circuit boards is used to execute the steps of the via hole filling electroplating method for printed circuit boards shown in the above embodiments. The via hole filling electroplating system 200 for printed circuit boards can be a single server or a server cluster, or the via hole filling electroplating system 200 for printed circuit boards can be a terminal, which can be a handheld terminal, a notebook computer, a wearable device, or a robot, etc.

[0109] As Figure 2 shown, the via hole filling electroplating system 200 for printed circuit board includes:

[0110] A via hole forming unit 201 for laser micro via hole processing of the printed circuit board to form micro via holes; and desmearing processing of the printed circuit board with micro via holes;

[0111] An electroplating processing unit 202 for black hole processing or direct electroplating processing of the desmeared printed circuit board; filling electroplating of the processed printed circuit board with acid copper filling hole special solution containing leveling agent, inhibitor and accelerator to preferentially adsorb and inhibit deposition at the hole opening under high current density and accelerate deposition in the hole under low current density to realize non-cavity filling from the hole bottom to the hole opening;

[0112] A program control unit 203 for controlling the filling electroplating process by using multi-stage electroplating current parameter program, using low current density for hole pre-plating in the initial stage to ensure uniform hole wall coverage, using pulse or periodic reverse current and stepwise increasing current density in the main filling hole stage, using acid copper filling hole special solution to quickly fill the via hole, and adjusting the parameters at the end of the filling period to ensure uniform copper thickness of the hole surface and avoid the occurrence of dish-shaped pits or excessive depression.

[0113] In some embodiments, the laser micro via hole processing of the printed circuit board to form micro via holes includes: using a computer to control a laser drilling device to process and form micro via holes with a diameter of 50-150 microns and a depth-diameter ratio of ≥3:1 in the specified 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.

[0114] In some embodiments, the desmearing processing of the printed circuit board with micro via holes includes: conveying the printed circuit board to an automatic desmearing station, immersing it in a sodium hydroxide solution with a concentration of 5-15%, maintaining the solution temperature at 50-80 degrees Celsius by a temperature control system, driving the board to swing at a rate of 2-5 revolutions per minute by a mechanical transmission device, processing for 2-10 minutes, and automatically rinsing the residual solution by a spraying system after the desmearing is completed.

[0115] In some embodiments, the black hole processing or direct plating processing of the de-glued printed circuit board includes: if the black hole processing is performed, immersing the board body into the carbon slurry solution through the horizontal conveying belt; the carbon particle concentration of the carbon slurry solution is 10-30 g / L; the speed is 1-5 m / min through the coating area, and the conductive carbon layer is formed by curing through the infrared drying line; the corresponding temperature of the infrared drying line is 80-120 ℃; if the direct plating processing is performed, immersing the board body into the palladium activation solution, and standing for 1-5 minutes to complete the catalytic activation; the corresponding palladium ion concentration of the palladium activation solution is 0.1-1 g / L, and the temperature is 20-50 ℃.

[0116] In some embodiments, the hole filling plating of the processed printed circuit board by using the acid copper plating hole filling special solution includes: loading the printed circuit board into the plating tank, maintaining the temperature of the acid copper plating solution at 25-45 ℃ and the pH value at 1.5-3.5 through the solution circulation system, wherein the leveling agent concentration is 0.1-1 g / L, the inhibitor concentration is 5-20 g / L, and the accelerator concentration is 0.01-0.5 g / L, the solution composition is monitored in real time by the online sensor, and the automatic liquid supplementing device is used to supplement the solution according to the preset proportion.

[0117] In some embodiments, the initial stage adopts low current density for in-hole pre-plating to ensure uniform coverage of the hole wall, including: controlling the initial output of the plating power supply to be 0.5-2 A / dm2 of direct current, lasting for 5-15 minutes, and feeding back to the preset control system in real time through the current density sensor, and when the hole wall copper layer thickness detection value reaches 0.5-1 μm, automatically triggering the main hole filling stage.

[0118] In some embodiments, after entering the main hole filling stage, pulse or periodic reverse current is adopted, and the current density is increased in steps to quickly fill the through hole by using the acid copper plating hole filling special solution, including: in the pulse current mode, the frequency is set to 10-1000 Hz and the duty cycle is set to 10%-50%, the current density starts from 2 A / dm2, and increases by 0.5-2 A / dm2 every 5-10 minutes in steps until reaching 5-15 A / dm2; in the periodic reverse current mode, the forward current and reverse current switching period is controlled to be 10-30 seconds, the reverse current duration is 1-5 seconds, and the reverse current intensity is 20%-50% of the forward current, and the forward current and reverse current switching period, the reverse current duration and the reverse current intensity are switched according to the preset rules by the plating power supply.

[0119] In some embodiments, the adjusting parameters at the end of filling to ensure uniform copper thickness on the hole surface and avoid the occurrence of dish-shaped pits or excessive depression includes: when the filling height in the hole reaches 80-90% of the hole depth, the electroplating power is automatically switched to a direct current mode, the current density is reduced to 1-3 ampere per square decimeter, and lasts for 5-10 minutes, while the hole surface is scanned online by a laser thickness gauge, and when the standard deviation of the copper layer thickness is less than or equal to 5%, it is determined that the filling is completed.

[0120] In some embodiments, the method further comprises: collecting process data in real time by a multi-sensor array deployed in the electroplating line, inputting a pre-trained machine learning model, dynamically optimizing the multi-stage electroplating current parameter program according to historical filling quality data, and forming a closed-loop feedback control; the machine learning model is iteratively trained periodically by new production data to adapt to the hole filling requirements of printed circuit boards with different hole diameters and board thicknesses; wherein the multi-sensor array includes current sensors, temperature sensors, laser thickness gauges and bath composition detectors; the historical filling quality data includes the core rate, the void rate and the copper thickness uniformity.

[0121] It should be noted that, for the convenience and brevity of description, the specific working process of the above-described through-hole filling electroplating system for printed circuit boards and each module can be clearly understood by those skilled in the art, and the corresponding content in each embodiment of the above-described through-hole filling electroplating method for printed circuit boards will not be described here.

[0122] The above-described through-hole filling electroplating method for printed circuit boards can be implemented in the form of a computer program, which can run on the device as shown in Figure 2 .

[0123] Please refer to Figure 3 , Figure 3 is a structural schematic block diagram of a computer device provided by the embodiments of the present application. The computer device includes a processor, a memory and a network interface connected through a device bus, wherein the memory can include a storage medium and an internal memory.

[0124] The storage medium can store an operating device and a computer program. The computer program includes program instructions which, when executed, can cause the processor to execute any one of the through-hole filling electroplating methods for printed circuit boards.

[0125] The processor is used to provide computing and control capabilities to support the operation of the entire computer device.

[0126] The internal memory provides an environment for the running of the computer program in the non-volatile storage medium, which, when executed by the processor, can cause the processor to execute any one of the through-hole filling electroplating methods for printed circuit boards.

[0127] The network interface is used for network communication, such as sending the assigned task, etc. Figure 3 The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the terminal to which the scheme of the present application is applied. A specific computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0128] It should be understood that the processor can be a central processing unit (CPU), and the processor can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0129] In one embodiment, the processor is configured to run a computer program stored in the memory to perform the following steps:

[0130] The printed circuit board is subjected to laser micro-via processing to form micro-vias, and the printed circuit board with micro-vias is subjected to glue removal processing.

[0131] The printed circuit board after glue removal is subjected to black hole processing or direct electroplating processing, and the printed circuit board after processing is subjected to hole filling electroplating using acid copper plating hole filling special solution. The acid copper plating hole filling special solution contains leveling agent, inhibitor and accelerator, so as to preferentially adsorb and inhibit deposition at the hole opening under high current density, accelerate deposition in the hole under low current density, and realize non-cavity filling from the hole bottom to the hole opening.

[0132] In the hole filling electroplating process, multi-stage electroplating current parameter programs are used for control. Low current density is used for hole pre-plating in the initial stage to ensure uniform hole wall coverage. After entering the main hole filling stage, pulse or periodic reverse current is used, and the current density is increased in steps. Acid copper plating hole filling special solution is used for rapid filling of the via, and the parameters are adjusted at the end of the filling period to ensure uniform copper thickness on the hole surface, avoiding the occurrence of dish-shaped pits or excessive depression.

[0133] In some embodiments, the laser micro-via processing of the printed circuit board to form micro-vias includes: using a computer to control a laser drilling device to process a micro-via with a diameter of 50-150 microns and a depth-diameter ratio of ≥3:1 in a specified 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.

[0134] In some embodiments, the glue removal processing of the printed circuit board with micro-vias includes: conveying the printed circuit board to an automatic glue removal station, immersing the printed circuit board in a sodium hydroxide solution with a concentration of 5-15%, maintaining the solution temperature at 50-80 degrees Celsius by a temperature control system, swinging the board body at a speed of 2-5 revolutions per minute by a mechanical transmission device, and processing for 2-10 minutes, and then automatically rinsing residual chemicals by a spraying system.

[0135] In some embodiments, the black hole processing or direct electroplating processing of the printed circuit board after glue removal includes: if the black hole processing is performed, immersing the board body in a carbon slurry solution by a horizontal conveyor belt; the carbon slurry solution has a carbon particle concentration of 10-30 grams per liter; passing through a coating area at a speed of 1-5 meters per minute, and curing to form a conductive carbon layer by an infrared drying line with a corresponding temperature of 80-120 degrees Celsius; if the direct electroplating processing is performed, immersing the board body in a palladium activation solution and standing for 1-5 minutes to complete the catalytic activation; the palladium activation solution has a corresponding palladium ion concentration of 0.1-1 gram per liter and a temperature of 20-50 degrees Celsius.

[0136] In some embodiments, the hole filling electroplating of the printed circuit board after processing using the special acid copper plating solution for hole filling includes: loading the printed circuit board into an electroplating tank, maintaining the temperature of the acid copper plating solution at 25-45 degrees Celsius and the pH value at 1.5-3.5 by a chemical solution circulation system, wherein the leveling agent concentration is 0.1-1 gram per liter, the inhibitor concentration is 5-20 grams per liter, and the accelerator concentration is 0.01-0.5 grams per liter, the chemical solution components are monitored in real time by an online sensor, and the automatic liquid supplementing device is used to supplement the chemicals according to a preset ratio.

[0137] In some embodiments, the initial stage uses a low current density for in-hole pre-plating to ensure uniform coverage of the hole wall, including: controlling the initial output of the electroplating power source to be a direct current of 0.5-2 ampere per square decimeter for 5-15 minutes, and feeding back to a preset control system in real time by a current density sensor, and automatically triggering the main hole filling stage when the hole wall copper layer thickness detection value reaches 0.5-1 microns.

[0138] In some embodiments, after the main via filling stage, pulse or periodic reverse current is used, and the current density is increased step by step, and the via is filled with acid copper plating special solution quickly, including: in the pulse current mode, the frequency is set to 10-1000 Hz and the duty cycle is 10%-50%, the current density starts from 2 A / dm2, and increases by 0.5-2 A / dm2 every 5-10 minutes, until it reaches 5-15 A / dm2; in the periodic reverse current mode, the forward current and reverse current switching period is controlled to be 10-30 seconds, the reverse current duration is 1-5 seconds, and the reverse current intensity is 20%-50% of the forward current, and the forward current and reverse current switching period, reverse current duration and reverse current intensity are switched by the electroplating power supply according to the preset rules.

[0139] In some embodiments, the parameters are adjusted at the end of the filling period to ensure uniform copper thickness on the hole surface and avoid the occurrence of dish-shaped pits or excessive depression, including: when the filling height in the hole reaches 80%-90% of the hole depth, the electroplating power supply automatically switches to direct current mode, the current density is reduced to 1-3 A / dm2, and lasts for 5-10 minutes, while the laser thickness gauge is used for online scanning of the hole surface, and when the standard deviation of the copper layer thickness is ≤5%, it is determined that the filling is completed.

[0140] In some embodiments, the method further comprises: collecting process data in real time through a multi-sensor array deployed in the electroplating line, inputting a pre-trained machine learning model, dynamically optimizing the multi-stage electroplating current parameter program according to historical filling quality data, and forming a closed-loop feedback control; the machine learning model is iteratively trained periodically through new production data to adapt to the via filling requirements of printed circuit boards with different hole diameters and board thicknesses; wherein the multi-sensor array includes current sensors, temperature sensors, laser thickness gauges and solution composition detectors; the historical filling quality data includes the core rate, the void rate and the copper thickness uniformity.

[0141] The application also provides a computer readable storage medium storing a computer program, which, when executed by a processor, causes the processor to implement the steps of the via filling electroplating method for printed circuit boards as provided in any of the embodiments of the application.

[0142] The computer readable storage medium can be an internal storage unit of the computer device, such as a hard disk or a memory of the computer device. The computer readable storage medium can also be an external storage device of the computer device, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc.

[0143] The above description is provided as an enabling teaching of the application and is not intended to limit its scope in any way. Any modification of the application in keeping with the spirit thereof that is apparent to those skilled in the art is to be considered within the scope of the application as defined by the appended claims.

Claims

1. A method for through-hole filling plating of printed circuit boards, characterized in that, The method comprises the following steps: laser micro-via processing is performed on a printed circuit board to form a micro-via; desmearing is performed on the printed circuit board with the micro-via; black hole processing or direct plating processing is performed on the printed circuit board after desmearing, which comprises: if the black hole processing is performed, the board is immersed in a carbon slurry solution through a horizontal conveying belt; the carbon particle concentration of the carbon slurry solution is 10-30 g / L; the board passes through a coating area at a speed of 1-5 m / min, is cured by an infrared drying line to form a conductive carbon layer; the corresponding temperature of the infrared drying line is 80-120 ℃; if the direct plating processing is performed, the board is immersed in a palladium activation solution and is placed for 1-5 min to complete catalytic activation; the corresponding palladium ion concentration of the palladium activation solution is 0.1-1 g / L, and the temperature is 20-50 ℃; the printed circuit board after processing is filled with a hole and plated by using acid copper plating hole-filling special chemicals, which comprises: the printed circuit board is loaded into a plating tank, the temperature of the acid copper plating solution is maintained at 25-45 ℃ and the pH value is maintained at 1.5-3.5 by using a chemical circulating system, wherein the concentration of a leveling agent is 0.1-1 g / L, the concentration of an inhibitor is 5-20 g / L, and the concentration of an accelerator is 0.01-0.5 g / L; the chemical components are monitored in real time by using an online sensor, and are supplemented by using an automatic liquid supplementing device according to a preset ratio; the acid copper plating hole-filling special chemicals contain a leveling agent, an inhibitor and an accelerator, so that the deposition is preferentially adsorbed on the hole opening at a high current density, and the deposition is accelerated in the hole at a low current density, thereby realizing non-cavity filling from the hole bottom to the hole opening; in the hole-filling plating process, a multi-stage plating current parameter program is used for control, a low current density is used for pre-plating in the hole in the initial stage to ensure uniform coverage of the hole wall, which comprises: the initial output of the plating power source is controlled to be a direct current of 0.5-2 A / dm2, and the direct current is maintained for 5-15 min; the current density sensor feeds back to a preset control system in real time; when the hole wall copper layer thickness detection value reaches 0.5-1 μm, the main hole-filling stage is automatically triggered; after entering the main hole-filling stage, pulse or periodic reverse current is used, and the current density is increased in steps, so that the through hole is quickly filled by using the acid copper plating hole-filling special chemicals; the parameters are adjusted at the end of the filling to ensure uniform copper thickness of the hole surface, thereby avoiding the occurrence of a dish-shaped pit or excessive depression.

2. The method of claim 1, wherein, The laser micro-via processing on the printed circuit board to form a micro-via comprises the following steps: a laser drilling device is controlled by a computer to process a micro-via with a diameter of 50-150 μm and a depth-diameter ratio of ≥3:1 in a specified area of the printed circuit board by using a laser power of 5-20 W, a pulse frequency of 10-50 kHz and a drilling speed of 50-200 mm / s.

3. The method of claim 1, wherein, The desmearing on the printed circuit board with the micro-via comprises the following steps: the printed circuit board is conveyed to an automatic desmearing station, is immersed in a sodium hydroxide solution with a concentration of 5-15%, the temperature of the solution is maintained at 50-80 ℃ by using a temperature control system, a mechanical transmission device drives the board to swing at a speed of 2-5 r / min, the processing time is 2-10 min, and the residual chemicals are automatically flushed by a spraying system after the desmearing is completed.

4. The method of claim 1, wherein, After the entering main filling hole stage, pulse or periodic reverse current is used, and the current density is increased in steps, and the through hole is quickly filled with acid copper plating hole filling special solution, including: In the pulse current mode, the frequency is set to 10-1000 Hz and the duty cycle is 10%-50%, the current density is 2 A / dm2, and the current density is increased by 0.5-2 A / dm2 every 5-10 minutes in steps, until 5-15 A / dm2 is reached; In the periodic reverse current mode, the forward current and reverse current switching period is controlled to be 10-30 seconds, the reverse current duration is 1-5 seconds, and the reverse current intensity is 20%-50% of the forward current, and the forward current and reverse current switching period, reverse current duration and reverse current intensity are switched by the electroplating power supply according to the preset rules.

5. The method of claim 1, wherein, The parameters are adjusted at the end of the filling to ensure uniform copper thickness on the hole surface and avoid the appearance of dished pits or excessive depression, including: When the filling height in the hole reaches 80%-90% of the hole depth, the electroplating power supply automatically switches to direct current mode, the current density is reduced to 1-3 A / dm2, and lasts for 5-10 minutes, while the laser thickness gauge is used for online scanning of the hole surface, and when the standard deviation of the copper layer thickness is ≤5%, it is determined that the filling is completed.

6. The method of claim 1, wherein, The method further comprises: Real-time acquisition of process data by a multi-sensor array deployed in the electroplating line, input of a pre-trained machine learning model, dynamic optimization of the multi-stage electroplating current parameter program by the machine learning model according to historical filling quality data, and formation of a closed-loop feedback control; the machine learning model is iteratively trained periodically by new production data to adapt to the filling hole requirements of printed circuit boards with different hole diameters and board thicknesses; The multi-sensor array includes current sensors, temperature sensors, laser thickness gauges and solution composition detectors; the historical filling quality data includes core rate, void rate and copper thickness uniformity.

7. A through hole plating system for printed circuit boards, characterized in that, Applied to the method of any one of claims 1-6, comprising: A through hole forming unit for laser micro-via processing of a printed circuit board to form a micro-via; and a glue removal treatment of the printed circuit board with the micro-via; The electroplating processing unit is used for black hole processing or direct electroplating processing of the printed circuit board after desmearing, comprising: if the black hole processing is performed, the board body is immersed into the carbon slurry solution through the horizontal conveying belt; the carbon particle concentration of the carbon slurry solution is 10-30 g / L; the board body passes through the coating area at a speed of 1-5 m / min, and is cured to form a conductive carbon layer through the infrared drying line; the corresponding temperature of the infrared drying line is 80-120 DEG C; if the direct electroplating processing is performed, the board body is immersed into the palladium activation liquid, and is placed for 1-5 minutes to complete the catalytic activation; the corresponding palladium ion concentration of the palladium activation liquid is 0.1-1 g / L, and the temperature is 20-50 DEG C; the printed circuit board after processing is filled with holes and electroplated by using the special acid copper plating solution for hole filling, comprising: the printed circuit board is loaded into the electroplating tank, the temperature of the acid copper plating solution is maintained at 25-45 DEG C and the pH value is 1.5-3.5 through the medicine circulating system, wherein the leveling agent concentration is 0.1-1 g / L, the inhibitor concentration is 5-20 g / L and the accelerator concentration is 0.01-0.5 g / L, the medicine composition is monitored in real time by the online sensor, and the automatic liquid supplementing device is supplemented according to the preset proportion; the special acid copper plating solution for hole filling contains leveling agent, inhibitor and accelerator, so as to preferentially adsorb and inhibit deposition at the hole opening under high current density, accelerate deposition in the hole under low current density, and realize non-cavity filling from the hole bottom to the hole opening; The program control unit is used for controlling the multi-stage electroplating current parameter program in the hole filling electroplating process, and the low current density is used in the initial stage to pre-plating in the hole to ensure uniform coverage of the hole wall, comprising: the initial output of the electroplating power supply is controlled to be 0.5-2 A / dm2 of direct current, and the duration is 5-15 minutes, the real-time feedback is realized through the current density sensor to the preset control system, when the hole wall copper layer thickness detection value reaches 0.5-1 micron, the main hole filling stage is automatically triggered; after entering the main hole filling stage, the pulse or periodic reverse current is used, and the current density is increased in steps, the special acid copper plating solution for hole filling is used to quickly fill the through hole, and the parameters are adjusted at the end of the filling period to ensure uniform copper thickness of the hole surface, and avoid the appearance of dish-shaped pits or excessive depression.

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