CN108456858B - Dry metallization method for drilling hole on circuit substrate - Google Patents
Dry metallization method for drilling hole on circuit substrate Download PDFInfo
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- CN108456858B CN108456858B CN201810189428.3A CN201810189428A CN108456858B CN 108456858 B CN108456858 B CN 108456858B CN 201810189428 A CN201810189428 A CN 201810189428A CN 108456858 B CN108456858 B CN 108456858B
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- copper
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/24—Vacuum evaporation
- C23C14/32—Vacuum evaporation by explosion; by evaporation and subsequent ionisation of the vapours, e.g. ion-plating
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
- H05K3/42—Plated through-holes or plated via connections
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing Of Printed Wiring (AREA)
- Printing Elements For Providing Electric Connections Between Printed Circuits (AREA)
- Insulated Metal Substrates For Printed Circuits (AREA)
Abstract
The invention discloses a dry metallization method for drilling holes on a circuit substrate, which adopts a vacuum ion plating process to plate copper films on the surface of the circuit substrate and the walls of the drilled holes to form a conductive layer; when the circuit substrate is a copper-clad substrate, the two-way pulse negative bias is applied to the copper-clad substrate and the auxiliary cathode of the plated hole while vacuum ion plating is carried out; when the circuit substrate is a non-metallized substrate, firstly, an aluminum or chromium priming layer and an aluminum copper or chromium copper gradient alloy transition layer are sequentially plated, and after a conductive layer is obtained, the plating process is the same as that of a copper-clad substrate; finally, vacuum aluminizing is closely carried out on the vacuum copper-plated layer to form an aluminum protective layer to prevent the copper film from being thermally oxidized. The invention is a dry plating process by vacuum equipment, is a clean treatment process without sewage, can replace the existing chemical plating process in the production of circuit boards, and avoids the pollution of complexing agents.
Description
Technical Field
The invention relates to the field of circuit board processing methods, in particular to a circuit substrate drilling dry metallization method.
Background
The circuit board can be industrially produced in a large scale, and the most important contribution is that the chemical copper plating adopted for the through holes of the circuit board lays a good foundation for the industrial, large-scale and automatic production of the circuit board due to the patent formula related to the chemical copper plating and the patent formula of the colloidal palladium which are launched in the 60 th century of the 20 th century. It also becomes one of the basic processes for manufacturing circuit boards accepted by various manufacturing enterprises. The basic process for producing the circuit board comprises the following steps:
blanking copper-clad plate, drilling, deburring, surface cleaning, weak corrosion, chemical copper plating, full plate copper plating, etching and electroplating pattern imaging, pattern copper plating, tin lead plating or nickel gold plating, resist stripping, etching, hot melting and solder mask coating
The manufacturing process of the circuit board needs a chemical copper plating process, and the chemical copper plating is a basic process and an important link in the manufacturing process of the circuit board. The chemical copper plating generally adopts formaldehyde as a reducing agent to carry out copper plating on Cu2+Reducing the copper into metal copper to deposit on the surface of the circuit board and the inner wall of the drilled hole to form a continuous copper film so as to achieve the purpose of conduction, and the principle is as follows:
in order to make the deposited metallic copper fine and smooth in structure and stabilize the electroless plating solution, it is necessary to control Cu in the solution2+The concentration of the complexing agent is high, so that the chemical plating solution needs to be added with a strong complexing agent, generally EDTA, the complexing agent, formaldehyde and other substances can bring harm to the environment, and the complexing agent, the formaldehyde and other substances can cause harm to the environment when the wastewater is treatedHas great difficulty, particularly in the treatment of wastewater containing EDTA complexing agent, and the prior technical method can not completely treat the wastewater. In addition, the maintenance and management of electroless copper plating baths is also somewhat difficult. But at present, no reliable replacement process exists, and electroless copper plating is still the key process in circuit board manufacturing.
In order to solve the problem of complexing agent pollution, the mature process methods proposed in the industry include a conductive ink method and a conductive resin method, but the method is poor in adhesion and insufficient in conductivity, is not suitable for fluorine-containing medium plate materials, is not popularized in production, and is only rarely applied to circuit boards with low quality requirements.
The dry coating technology has no pollution in the production process, and is widely applied to the processes of ceramic substrates and packaging substrates at present. However, the presently disclosed technology cannot solve the problems because the requirements of the circuit substrate on surface coating adhesion, deep hole coating capability and mass production capability cannot be met, and thus, the technology is not applied to the circuit board industry.
The vacuum ion plating method of the inner wall of the small hole under the guidance of the electric field (patent No. 201710328936.0) effectively solves the problem of deep hole coating of the circuit substrate through the auxiliary cathode, but can not ensure that the deep hole coating capability and the surface coating adhesive force of the circuit substrate simultaneously meet the requirements.
Summary of the inventionit is an object of the present invention to provide a method for drilling dry metallization of a circuit substrate.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a circuit substrate drilling dry metallization method is characterized in that the circuit substrate is divided into a copper-clad substrate and a non-metal substrate, after the copper-clad substrate is drilled, metal copper is arranged on the surface, the wall of a drilled hole is non-metal, and after the non-metal substrate is drilled, the surface and the wall of the drilled hole are both non-metal: plating a copper film on the surface of the circuit substrate and the wall of the drilled hole by adopting a vacuum ion plating process to form a conductive layer; and the copper-clad substrate applies bidirectional pulse negative bias between the copper-clad substrate and the hole-plating auxiliary cathode during vacuum ion plating, namely when the first pulse is applied to the copper-clad substrate, the hole-plating auxiliary cathode is grounded, and then when the second pulse is applied to the hole-plating auxiliary cathode, the copper-clad substrate is grounded, and the steps are alternately repeated until the thickness of the plated film meets the requirement.
The circuit substrate drilling dry metallization method is characterized by comprising the following steps: before copper plating, the non-metal substrate is primed with aluminum plating or chromium plating, and then is transited by aluminum copper or chromium copper gradient alloy to form a conductive layer, and then the plating process is the same as that of the copper-clad substrate, and the plating is continuously completed in a vacuum chamber. According to the gradient direction, the content of aluminum or chromium is gradually changed from 100% to 0, and the content of copper is gradually changed from 0 to 100% in the aluminum-copper or chromium-copper gradient alloy transition layer.
The circuit substrate drilling dry metallization method is characterized by comprising the following steps: vacuum aluminizing is carried out immediately after the vacuum copper film is plated, the surface of the copper film is covered, and a protective film is formed to prevent the copper film from being thermally oxidized; and then taking the circuit substrate out of the vacuum chamber to obtain the circuit substrate with the drill hole wall and the surface coating meeting the requirements, wherein the aluminized protective layer is removed before the circuit substrate enters the next working procedure.
The invention has the advantages that:
1. the vacuum ion plating principle is utilized to carry out metallization film coating on the drilling hole of the circuit substrate in a non-water state, and no sewage is discharged in the process.
2. The chemical plating process in the prior circuit board production is replaced, the pollution of a complexing agent is avoided, the wastewater treatment in the circuit board production is simplified, and the treatment cost is greatly reduced.
3. The requirements of the circuit board on surface coating adhesive force, deep hole coating capability and batch production capability are met by adopting bidirectional pulse bias, gradient alloy coating and coating layer thermal protection.
4. The processing quality of the circuit board, particularly the hole line quality of the fluorine-containing medium substrate, is improved by improving the line width precision of the circuit board and the reliability of drilling metallization.
5. The process is simplified.
Drawings
FIG. 1 is a schematic diagram of the principle of the two-way pulse negative bias vacuum ion plating in the present invention.
1-a vacuum chamber, 2-a circuit substrate, 3-an ion source, 4-a plating hole auxiliary cathode and 5-a shielding plate; 6-drilling the circuit substrate.
FIG. 2 is a schematic view of the structure of the present invention for coating a copper-clad substrate.
7-non-metal layer of copper clad substrate. 8-copper-clad layer of copper-clad substrate, 9-copper-clad layer, and 10-aluminum plating layer.
FIG. 3 is a schematic view of the structure of the present invention for coating a film on the surface of a non-metallic substrate.
11-nonmetal substrate, 12-aluminum or chromium bottom layer, 13-aluminum copper or chromium copper gradient alloy transition plating layer, 14-copper plating layer and 15-aluminum plating layer.
Detailed Description
A circuit substrate drilling dry metallization method comprises the steps that a circuit substrate is divided into a copper-clad substrate and a non-metal substrate, after the copper-clad substrate is drilled, metal copper is arranged on the surface, the wall of a drilled hole is non-metal, after the non-metal substrate is drilled, the surface and the wall of the drilled hole are both non-metal, and a vacuum ion plating process is adopted to plate copper films on the surface of the circuit substrate and the wall of the drilled hole to form a conductive layer; and the copper-clad substrate applies bidirectional pulse negative bias between the copper-clad substrate and the hole-plating auxiliary cathode during vacuum ion plating, namely when the first pulse is applied to the copper-clad substrate, the hole-plating auxiliary cathode is grounded, and then when the second pulse is applied to the hole-plating auxiliary cathode, the copper-clad substrate is grounded, and the steps are alternately repeated until the thickness of the plated film meets the requirement.
Before copper plating, the non-metal substrate is primed with aluminum plating or chromium plating, and then is transited by aluminum copper or chromium copper gradient alloy to form a conductive layer, and then the plating process is the same as that of the copper-clad substrate, and the plating is continuously completed in a vacuum chamber. According to the gradient direction, the content of aluminum or chromium is gradually changed from 100% to 0, and the content of copper is gradually changed from 0 to 100% in the aluminum-copper or chromium-copper gradient alloy transition layer.
Vacuum aluminizing is carried out immediately after the vacuum copper film is plated, the surface of the copper film is covered, and a protective film is formed to prevent the copper film from being thermally oxidized; and then taking the circuit substrate out of the vacuum chamber to obtain the circuit substrate with the drill hole wall and the surface coating meeting the requirements, wherein the aluminized protective layer is removed before the circuit substrate enters the next working procedure.
The invention adopts a vacuum ion plating process to plate copper films on the surface of a circuit substrate and the wall of a drill hole to form a conductive layer; the circuit substrate is divided into a copper-clad substrate and a non-metal substrate, after the copper-clad substrate is drilled, metal copper is arranged on the surface, the wall of the drilled hole is non-metal, and after the non-metal substrate is drilled, the surface and the wall of the drilled hole are both non-metal.
And the copper-clad substrate is subjected to bidirectional pulse negative bias between the copper-clad substrate and the auxiliary cathode of the plated hole while vacuum coating is carried out. As shown in fig. 1; in the vacuum chamber 1, the film coating surface of the copper-clad substrate 2 is parallel to the ion source 3, the reverse surface of the copper-clad substrate 2 is parallel to the hole-plating auxiliary cathode 4, and a shielding plate 5 is arranged around the copper-clad substrate 2; when the first pulse negative bias is connected with the copper-clad substrate 2, the plating hole auxiliary cathode 4 is grounded, the copper-clad substrate 2 is negatively charged, and under the attraction of negative charges, metal cations are accelerated to impact on the surface of the copper-clad substrate and form a film; and then, connecting a second pulse negative bias with the auxiliary cathode 4 of the plated hole, grounding the copper-clad substrate 2, moving metal cations to the auxiliary cathode 4 through the drilled hole 6 under the guidance of an electric field, and colliding part of metal ions on the hole wall to form a film, and repeating the steps alternately until the film thickness is met. The structure of the coating is shown in figure 2; the non-metal layer 7 of the copper-clad substrate is provided with a copper-clad layer 8, and a copper-clad layer 10 is plated after vacuum ion plating a copper layer 9. All the coatings are continuously completed in the vacuum chamber. The coating structure of the borehole wall is the same as the substrate surface.
In the invention, for the copper-clad substrate, negative bias is applied to the copper-clad substrate while vacuum coating is carried out, so as to improve the adhesion between the coating and the surface of the copper-clad substrate; applying negative bias to the auxiliary cathode of the plated hole to improve the metal deposition efficiency of the drilled hole; when negative bias is applied to the copper-clad substrate, metal ions are rarely deposited on the inner wall of the drill hole due to the shielding effect of an electric field; when negative bias is applied to the auxiliary cathode of the plated hole, the adhesive force of the plated film on the surface of the copper-clad substrate cannot meet the requirement; when negative bias is applied to the copper-clad substrate and the hole-plating auxiliary cathode simultaneously, the hole-plating auxiliary cathode does not function, and the metal deposition efficiency of the drilled hole is low. In order to solve the contradiction, the negative bias of the bidirectional alternating pulse is implemented between the copper-clad substrate and the auxiliary cathode of the plated hole, so that the film coating adhesion and the hole wall film coating capacity of the surface of the copper-clad substrate are considered, the film coating on the surface of the copper-clad substrate is not the purpose, but the surface of the substrate cannot be avoided during the film coating by drilling, so the surface needs to be considered, otherwise, the surface can peel.
Before copper plating, the non-metal substrate is primed with aluminum plating or chromium plating, and then is transited by aluminum copper or chromium copper gradient alloy to form a conductive layer, and then the plating process is the same as that of the copper-clad substrate. The structure of the coating is shown in figure 3; the non-metal substrate 11 is first plated with an aluminum or chromium bottom layer 12, then plated with an aluminum-copper or chromium-copper gradient alloy transition 13, and then plated with a copper layer 14 and then with an aluminum plating layer 5, all the plating layers being continuously completed in a vacuum chamber. The coating structure of the borehole wall is the same as the substrate surface.
In the invention, for the non-metal substrate, the adhesion of copper plated on the surface is insufficient, the non-metal is an insulating material, and negative bias cannot be applied. Before copper plating, aluminum or chromium is used for priming, aluminum copper or chromium copper gradient alloy is used for transition, good coating adhesion can be obtained, and after a conductive layer is formed, negative bias is applied to ensure interlayer adhesion. According to the gradient direction, the content of aluminum or chromium is gradually changed from 100% to 0, and the content of copper is gradually changed from 0 to 100% in the aluminum-copper or chromium-copper gradient alloy transition layer.
Vacuum aluminizing is carried out after the copper film is vacuum-plated, the surface of the copper film is covered, a protective film is formed, then the circuit substrate is taken out from the vacuum environment, and the circuit substrate with the metal layer on the wall of the drilled hole and the surface is obtained.
In the invention, the substrate is heated after vacuum coating, the substrate leaves the vacuum chamber, the copper film is quickly oxidized to lose conductivity, if the substrate is cooled in the vacuum chamber, 3 ~ 5 hours are needed, the period is long, the efficiency is low, vacuum aluminum plating is carried out after the vacuum copper film plating, the vacuum aluminum plating is used as a technological process protective layer, the thermal oxidation of the copper film is prevented, the cooling time is shortened, and the aluminum protective layer is removed by alkali solution before the next working procedure.
The dry metallization method for drilling the circuit substrate comprises the following specific implementation steps:
1. cleaning brush wire
Removing burrs at the edge of a drilled hole of the circuit substrate;
2. ultrasonic cleaning
Removing dust on the surface of the circuit substrate and in the drill hole;
3. vacuum plasma etching
Removing oxides, pollutants and surface glue layers on the surface of the circuit substrate;
4. vacuum ion plating
Vacuum ion plating of a copper-clad substrate: as shown in fig. 1; in the vacuum chamber 1, the film coating surface of the copper-clad substrate 2 is parallel to the ion source 3, the reverse surface of the copper-clad substrate 2 is parallel to the hole-plating auxiliary cathode 4, and a shielding plate 5 is arranged around the copper-clad substrate 2; starting an ion source 3 for copper plating, and applying bidirectional pulse negative bias between the copper-clad substrate 2 and the auxiliary cathode 4 for plating holes until the thickness of a copper film meets the requirement; and (3) closing the copper plating ion source, starting the aluminum plating ion source, and applying bidirectional pulse negative bias between the copper-clad substrate 2 and the auxiliary cathode 4 until the thickness of the aluminum film meets the requirement. And taking out the copper-clad substrate 2 from the vacuum chamber, and finishing the process. The above coating is continuously completed in a vacuum chamber. The aluminum plating layer is removed by alkali solution before the circuit substrate enters the next working procedure. The structure of the coating is shown in figure 2; the non-metal layer 7 of the copper-clad substrate is provided with a copper-clad layer 8, a copper layer 9 is plated in vacuum ion, and then an aluminum plating layer 10.
Vacuum ion plating of a non-metal substrate: before copper plating, aluminum plating or chromium plating is used for priming, aluminum copper or chromium copper gradient alloy is used for transition, and after a conductive layer is formed, the plating process is the same as the vacuum ion plating process of the copper-clad substrate. The structure of the coating is shown in figure 3; the non-metal substrate 11 is first plated with an aluminum or chrome bottom layer 12, then plated with an aluminum-copper or chrome-copper gradient alloy transition layer 13, then plated with a copper layer 14, and then plated with an aluminum plating layer 15.
Claims (1)
1. A circuit substrate drilling dry metallization method is characterized in that the circuit substrate is divided into a copper-clad substrate and a non-metal substrate, after the copper-clad substrate is drilled, metal copper is arranged on the surface, the wall of a drilled hole is non-metal, and after the non-metal substrate is drilled, the surface and the wall of the drilled hole are both non-metal: plating a copper film on the surface of the circuit substrate and the wall of the drilled hole by adopting a vacuum ion plating process to form a conductive layer; the copper-clad substrate applies bidirectional pulse negative bias between the copper-clad substrate and the hole-plating auxiliary cathode during vacuum ion plating, namely when the first pulse is applied to the copper-clad substrate, the hole-plating auxiliary cathode is grounded, and then when the second pulse is applied to the hole-plating auxiliary cathode, the copper-clad substrate is grounded, and the steps are alternately repeated until the thickness of the plated film meets the requirement;
before copper plating, the non-metal substrate is primed with aluminum plating or chromium plating, and then is transited by aluminum copper or chromium copper gradient alloy to form a conducting layer, and then the plating process is the same as that of the copper-coated substrate, and the plating is continuously finished in a vacuum chamber;
according to the gradient direction, the content of aluminum or chromium is gradually changed from 100% to 0, and the content of copper is gradually changed from 0 to 100% in the aluminum-copper or chromium-copper gradient alloy transition layer;
vacuum aluminizing is carried out immediately after the vacuum copper film is plated, the surface of the copper film is covered, and a protective film is formed to prevent the copper film from being thermally oxidized; and then taking the circuit substrate out of the vacuum chamber to obtain the circuit substrate with the drill hole wall and the surface coating meeting the requirements, wherein the aluminized protective layer is removed before the circuit substrate enters the next working procedure.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810189428.3A CN108456858B (en) | 2018-03-08 | 2018-03-08 | Dry metallization method for drilling hole on circuit substrate |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810189428.3A CN108456858B (en) | 2018-03-08 | 2018-03-08 | Dry metallization method for drilling hole on circuit substrate |
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| CN108456858A CN108456858A (en) | 2018-08-28 |
| CN108456858B true CN108456858B (en) | 2020-01-10 |
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| JPWO2004040604A1 (en) * | 2002-10-30 | 2006-03-02 | 三井金属鉱業株式会社 | Copper foil with dielectric layer for forming capacitor layer, copper clad laminate for forming capacitor layer using copper foil with dielectric layer, and method for producing copper foil with dielectric layer for forming capacitor layer |
| CN2773074Y (en) * | 2005-01-05 | 2006-04-19 | 上海宏大铝业装饰有限公司 | Vacuum ion copper-plating porcelain |
| CN106211634A (en) * | 2016-07-29 | 2016-12-07 | 合肥开泰机电科技有限公司 | Circuit boring dry method method for metallising |
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