CN113993303A - Method for metallizing holes of mixed-pressure circuit board - Google Patents
Method for metallizing holes of mixed-pressure circuit board Download PDFInfo
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- CN113993303A CN113993303A CN202111255129.3A CN202111255129A CN113993303A CN 113993303 A CN113993303 A CN 113993303A CN 202111255129 A CN202111255129 A CN 202111255129A CN 113993303 A CN113993303 A CN 113993303A
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Images
Classifications
-
- 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
-
- 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
- H05K3/423—Plated through-holes or plated via connections characterised by electroplating method
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Manufacturing Of Printed Wiring (AREA)
Abstract
The invention provides a method for metallizing holes of a mixed-pressure circuit board, which comprises the following steps: baking a board, performing plasma cleaning and activation, plating holes, neutralizing and repeatedly plating holes for one time to obtain a hole-metallized mixed-pressing circuit board; according to the method, a plasma activation step is added on the basis of the traditional process, the hole plating process is adjusted from one time to two times, the first electroplating copper adopts a flash plating process, the plating layer is only thickened by 3-5 mu m, the problem of the bonding force between the electroplating copper and surface copper is effectively avoided, and the uniformity of the plating layer in the hole is ensured; in addition, the neutralization step uses a surface conditioning agent, so that the plating leakage phenomenon of a mixed pressing area is avoided; the method does not need to add a new production line, has small investment and high return, can be applied to various types of plates, and is suitable for large-scale industrial popularization.
Description
Technical Field
The invention belongs to the field of printed circuit board processing, and particularly relates to a method for metalizing holes of a mixed-pressure circuit board.
Background
With the high-speed development of electronic communication technology, in order to realize high-speed and high-fidelity transmission of signals, high-frequency circuit boards are increasingly used in communication equipment; the dielectric material adopted by the high-frequency plate has excellent electrical property and good chemical stability, and the design of the multi-layer high-frequency plate is based on the factors of cost saving, bending strength improvement, electromagnetic interference control and the like, and is often in the form of a mixed pressing plate, which is called as a high-frequency mixed pressing plate. The high-frequency mixed-compression material is selected and stacked and combined, the design is various and is incompletable, wherein the soft and hard combined board has the stability of a hard board and the soft board can be assembled in a three-dimensional mode, and the development prospect is very considerable.
In the mixed-compression material for the soft and hard combined plate with a large market quantity at present, Polytetrafluoroethylene (PTFE) material has the excellent performances of high temperature resistance, low temperature resistance and ageing resistance, and the dielectric property of the PTFE material is almost irrelevant to the change of temperature and external frequency, so that the PTFE is promoted to become a high-frequency plate preferred by customers; polyimide (PI) materials are often made into PI films, are used as printed flexible circuit boards, have the advantages of three-dimensional wiring, large information storage capacity due to multi-layer arrangement and the like, and are widely applied to small electronic devices such as mobile phones and the like; the glass fiber is mainly made into glass fiber cloth, and the glass fiber cloth and other film layers form an insulating medium layer together after being soaked, the glass fiber has good insulativity, heat resistance and corrosion resistance, but due to poor flexibility, bonding defects often occur in a composite layer of a printed circuit board, a bonding incomplete area is formed, and the yield of the printed circuit board is influenced. Besides the defects in the composite layer, the technical problems of in-hole copper breaking, unqualified hole wall plating thickness, separation of surface copper and chemical copper plating layers and the like easily occur in a special mixed pressing area in a hole forming and copper plating process of the high-frequency mixed pressing plate material.
CN108200734A discloses a method for producing a positive concave etching printed circuit board, which can effectively realize good concave etching effect by combining and optimizing production flow and adopting a method of 'a potassium permanganate glue removing method + a plasma glue removing method + a potassium permanganate glue removing method'. The method not only can completely remove the drilling dirt of the wall of the non-metallized hole, but also can etch the insulating part (comprising epoxy resin and glass fiber yarn) to a certain depth to ensure that the inner layer copper completely protrudes out of the wall of the hole, and three-side electrical connection is formed after copper deposition, full-plate electroplating and hole wall copper plating processing, thereby realizing high-reliability electrical connection between layers. The method uses potassium permanganate and plasma to remove glue, so that the process flow is complicated and environmental pollution is caused.
CN107072075A discloses a method for improving copper breakage in holes of Printed Circuit Boards (PCBs) made of PTFE materials, comprising: stacking an aluminum sheet, a cold punching plate, a PCB and a phenolic aldehyde plate on the plane of a machine table from top to bottom in sequence, and drilling by using a UC drill bit from top to bottom, wherein the PCB is a PTEF material PCB; removing glue by plasma; depositing copper, wherein the first copper deposition comprises oil removal, microetching, presoaking, activation, chemical copper and cylinder discharge; the second copper deposition comprises presoaking, activation, chemical copper and cylinder discharge; and (4) full-board electroplating, namely, performing pickling treatment on the PCB subjected to the secondary copper deposition, and then putting the PCB into an electroplating cylinder for full-board electroplating to increase the thickness of copper on the board surface and in the holes to the required thickness. According to the method for improving the internal copper fracture of the hole of the PTFE material PCB, the copper precipitation effect on the hole wall of the PTFE material PCB is ensured by combining the board stacking drilling with the secondary copper precipitation, the problem of internal copper fracture is avoided, and the product quality is improved. The method uses plasma to remove the glue, but the effect is better when only the defects on the hard plate are processed, and the problem of irregular coating in the mixing area cannot be well solved when the more complex structure in the mixing plate is processed.
CN108471680A discloses a hole metallization process of a circuit board, which is an electroless copper plating process or a direct electroplating process, and includes baking the circuit board before degreasing. The electroless copper plating process comprises the following steps: sequentially carrying out desmearing, baking, oil removal, micro-etching, presoaking, activation reduction/acceleration and chemical copper plating on the circuit board. The hole metallization process provided by the invention can effectively avoid the phenomenon of plating leakage on the hole wall of the circuit board, improve the bonding strength between the conductive material and the hole wall, prevent the conductive material and the hole wall from being separated, only need one-time hole metallization and one-time electroplating to completely cover the hole wall, and reduce the procedures required by the hole metallization. However, in actual production, metal defects in a special surface area and holes still exist after the circuit board with a more complex structure is processed after mixed pressing.
With the continuous advance of the market and science and technology, the application of mobile devices is increasing, and the mixed-compression boards made of various functional materials are becoming more and more popular, and the above technical problems need to be solved by improving the production process of printed circuit boards.
Disclosure of Invention
Aiming at the problems that the chemical copper plating in the mixed pressing circuit board hole is incomplete, the plating leakage condition exists, the hole wall can not be completely covered after electroplating thickening, the plating leakage part is mainly in the mixed pressing special material area (such as a PI area, a PTFE area and a filler area) or a glass fiber area, the bonding force of the electroplated copper and the surface copper is poor, the copper layer is separated and the like, the invention provides the method for metallizing the mixed pressing circuit board hole, the plasma activation step is added, the problem of the bonding force of the electroplated copper and the surface copper can be effectively avoided, the hole plating process is adjusted from one time to two times, the uniform plating layer in the hole is ensured, the bonding between the dielectric layers of the glass fiber area and the filler area is good, the copper layer in the special material area can be protected from being bitten into, the cationic surface modifier is used in the neutralization step, the charges in the inorganic material area and the glass fiber area are adjusted, is beneficial to the deposition of chemical copper and avoids the phenomenon of plating leakage.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for hole metallization of a hybrid circuit board, comprising the steps of:
(1) baking the plate: baking the mixed-pressing circuit board to obtain a dry plate;
(2) plasma cleaning and activating: the dried plate is sequentially subjected to vacuumizing, plasma cleaning and plasma activation to obtain a pretreated plate;
(3) chemical hole plating: sequentially carrying out hole trimming, microetching, presoaking, activating, post-activation treatment and chemical copper plating on the pretreated plate;
(4) primary electroplating: sequentially carrying out oil removal, acid cleaning and primary copper electroplating on the plate treated in the step (3);
(5) neutralizing: treating the plate subjected to the primary copper electroplating by using a surface conditioning agent to obtain a regular plate;
repeating the step (3) once for the structured plate;
(6) secondary electroplating: and (4) sequentially carrying out oil removal, acid cleaning and secondary copper electroplating on the board treated in the step (3) to obtain the hole-metallized mixed-compression circuit board.
The method provided by the invention can effectively avoid the problem of the bonding force between the electroplated copper and the surface copper by adding the step of activating the plasma; the hole plating process is adjusted from one time to two times in the traditional process, so that the copper layer in the special material area can be protected from being corroded by refined operation, and the uniform plating layer in the hole is ensured, and the good combination between the glass fiber area and the dielectric layer in the filler area is ensured; and in the neutralization step, a cationic surface modifier is used for adjusting the charges of the inorganic material area and the glass fiber area, so that the copper deposition in the second electroless copper plating is facilitated, and the plating leakage phenomenon in a mixed pressing area is further avoided.
In a preferred embodiment of the present invention, the thickness of the plating layer in the first plating in step (4) is increased by 3to 5 μm, and may be, for example, 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm, or 5 μm, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.
Before electroless copper plating in the traditional process, the plate needs to be subjected to neutralization and microetching treatment, and if the copper layer in a special material area is too thick, the phenomenon of corrosion biting can occur to cause the coating to be unevenly distributed.
Preferably, the thickness of the plating layer in the secondary plating in step (6) is increased by 5to 30 μm, and may be, for example, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, 28 μm, or 30 μm, but is not limited to the values listed, and other values not listed in the range of the values are also applicable.
As a preferred technical scheme of the invention, all steps after the step (1) are completed within 4 h.
The baking plate process is easy to realize in production, the field is not limited by the original production line (no matter vertical line or horizontal line) of a client, the space can be independently planned for operation, and only the baking plate is needed before plasma treatment.
All steps after the step (1) need to be completed within 4h, because free radicals are generated on the surface after the Plasma treatment, the decay of the free radicals is mainly caused by that the standing time is too long, PTFE molecular chains move, a complex reaction is generated among the free radicals to generate new chemical bonds but new free radicals are not generated, in addition, the free radicals can obtain one hydrogen atom from the surrounding environment to form hydride so as to reduce the concentration of the free radicals, and if the copper plating operation is not completed within a certain time, the effect of the post-treatment is poor.
Preferably, the mixed-voltage circuit board comprises a hard circuit board, a flexible circuit board or a rigid-flex circuit board.
The printed circuit board is divided into a hard circuit board, a flexible circuit board and a rigid-flexible combined board according to the hardness degree, the hard circuit board is called as a hard board for short and cannot be bent, and common materials of the hard circuit board comprise: polyester glass felt laminates, phenolic paper laminates, epoxy glass cloth laminates, and the like; the flexible circuit board is called as a 'soft board' for short, is a printed circuit board made of flexible insulating base materials (mainly polyimide or polyester films) and can be bent; the soft and hard combined board is a circuit board with the characteristics of a soft board and a hard board, which is formed by combining a flexible circuit board and a hard circuit board according to relevant process requirements through processes such as pressing and the like.
Preferably, the hybrid circuit board comprises any one or a combination of two or more of polyimide, polytetrafluoroethylene, glass fiber or filler, wherein typical but non-limiting combinations include a combination of polyimide and polytetrafluoroethylene, a combination of polyimide and glass fiber, a combination of glass fiber and polytetrafluoroethylene, a combination of polyimide and filler, a combination of polytetrafluoroethylene and polytetrafluoroethylene, and the like, but are not limited to the listed combinations, and other combinations not listed in the scope are also applicable.
Preferably, the temperature of the baking is 100-150 ℃, preferably 120-130 ℃, and can be, for example, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃ or 150 ℃, but is not limited to the recited values, and other unrecited values in the range of the values are also applicable.
Preferably, the baking time is 20-300min, preferably 120-240min, such as 20min, 40min, 60min, 80min, 100min, 120min, 140min, 180min, 200min, 220min, 240min, 280min or 300min, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.
As a preferred embodiment of the present invention, the plasma cleaning activation in step (2) includes: the method comprises the steps of vacuumizing the dried plate in plasma equipment to initial pressure, introducing cleaning gas, keeping the cleaning pressure for plasma cleaning after the cleaning pressure is reached, introducing activating gas, and keeping the activating pressure for plasma activation after the activating pressure is reached.
Compared with the plasma cleaning in the prior art, the plasma cleaning activation in the invention adds an activation step, and activates the PTFE material surface on the basis of completing glue removal on the PI substrate surface, thereby being beneficial to improving the bonding force of the original plating layer on the surface of the mixed-pressure circuit board and the plating layer in the subsequent chemical copper plating.
Preferably, the initial pressure is 0.05to 0.15torr, preferably 0.08to 0.12torr, for example, 0.05torr, 0.07torr, 0.08torr, 0.09torr, 0.1torr, 0.12torr or 0.15torr, but is not limited to the recited values, and other values not recited in this range are also applicable.
Preferably, the cleaning gas includes a mixed gas of oxygen, nitrogen, carbon tetrafluoride and argon.
Preferably, the total flow rate of oxygen, nitrogen and carbon tetrafluoride is 2.3 to 2.8L/min, and may be, for example, 2.3L/min, 2.4L/min, 2.5L/min, 2.6L/min, 2.7L/min or 2.8L/min, but is not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the oxygen gas has a volume flow fraction of 60-90%, for example 60%, 65%, 70%, 75%, 80%, 85% or 90%, but not limited to the recited values, and other non-recited values within this range are equally applicable.
Preferably, the nitrogen gas has a volume flow fraction of 10-40%, for example 10%, 15%, 20%, 25%, 30%, 35% or 40%, but not limited to the recited values, and other values not recited within this range are equally applicable.
Preferably, the volume flow fraction of carbon tetrafluoride is 6 to 12%, and may be, for example, 6%, 7%, 8%, 9%, 10%, 11%, or 12%, but is not limited to the recited values, and other values not recited within the range of values are also applicable.
Preferably, the flow rate of argon is 1.0-1.8L/min, for example 1.0L/min, 1.2L/min, 1.4L/min, 1.5L/min, 1.6L/min or 1.8L/min, but not limited to the values listed, and other values not listed in this range are equally applicable.
Preferably, the cleaning pressure is 0.2to 0.3torr, preferably 0.23to 0.28torr, for example, 0.2torr, 0.22torr, 0.23torr, 0.25torr, 0.27torr, 0.28torr or 0.3torr, but is not limited to the recited values, and other values not recited in this range are also applicable.
Preferably, the plasma cleaning time is 15-25min, preferably 18-22min, for example 15min, 17min, 18min, 20min, 21min, 23min or 25min, but is not limited to the values listed, and other values not listed in this range of values are equally applicable.
Preferably, the activating gas includes any one or a combination of two or more of helium, nitrogen or oxygen, wherein typical but non-limiting combinations are helium and nitrogen, helium and oxygen, or nitrogen and oxygen, and the like, but not limited to the listed combinations, and other combinations not listed are also applicable within the scope.
Preferably, the activation pressure is 0.2to 0.3torr, preferably 0.23to 0.28torr, for example, 0.2torr, 0.22torr, 0.23torr, 0.25torr, 0.27torr, 0.28torr or 0.3torr, but is not limited to the recited values, and other values not recited in this range are also applicable.
Preferably, the plasma activation time is 35-45min, preferably 38-42min, for example 35min, 37min, 38min, 40min, 41min, 43min or 45min, but is not limited to the values listed, and other values not listed in this range of values are equally applicable.
As a preferred technical solution of the present invention, the pore-forming in step (3) includes soaking in a pore-forming solution, taking out, and washing with deionized water.
Preferably, the temperature of the whole pore is 40-60 ℃, preferably 45-55 ℃, for example 40 ℃, 42 ℃, 43 ℃, 45 ℃, 47 ℃, 48 ℃, 50 ℃, 52 ℃, 53 ℃, 55 ℃, 57 ℃, 58 ℃ or 60 ℃, but is not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the time for completion of the pores is 30 to 150s, preferably 60 to 100s, and may be, for example, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, 120s or 150s, but is not limited to the recited values, and other values not recited within the range of values are also applicable.
Preferably, the microetching comprises soaking in a microetching solution, taking out, and washing with deionized water.
Preferably, the microetching solution comprises an acidic microetching solution. Preferably, the acidic microetching solution comprises a sulfuric acid-persulfate microetching solution or a sulfuric acid-hydrogen peroxide microetching solution.
Preferably, the sulfuric acid-persulfate microetching solution comprises a sulfuric acid solution.
Preferably, the sulfuric acid-persulfate microetching solution further comprises sodium persulfate and/or ammonium persulfate.
Preferably, the sulfuric acid-hydrogen peroxide microetching solution comprises a sulfuric acid solution and hydrogen peroxide.
Preferably, the sulfuric acid-hydrogen peroxide microetching solution further comprises a hydrogen peroxide stabilizer.
Preferably, the hydrogen peroxide stabilizer comprises at least one or a combination of two or more of ethanolamine, methane diamine or isooctyl amine, wherein typical but non-limiting combinations are ethanolamine and methane diamine, isooctyl amine and methane diamine, ethanolamine and isooctyl amine, and the like, but is not limited to the listed combinations, and other combinations not listed in the scope are also applicable.
Preferably, the microetching temperature is 25to 35 ℃, preferably 28to 32 ℃, and may be, for example, 25 ℃, 26 ℃, 27 ℃, 28 ℃, 29 ℃, 30 ℃, 31 ℃, 32 ℃, 33 ℃, 34 ℃ or 35 ℃, but is not limited to the recited values, and other values not recited within the range of values are also applicable.
Preferably, the microetching period is from 30 to 60s, preferably from 40 to 50s, and may be, for example, 30s, 35s, 40s, 45s, 50s, 55s or 60s, but is not limited to the values recited, and other values not recited within the range of values are also applicable.
Preferably, the microetching reduces the plating layer of the plate after the whole hole by 0.3-1.5 μm.
In a preferred embodiment of the present invention, the pre-dipping in step (3) comprises immersing in a pre-dip solution and then taking out.
Preferably, the temperature of the pre-dip is 15-35 ℃, preferably 20-30 ℃, and may be, for example, 15 ℃, 18 ℃, 20 ℃, 22 ℃, 25 ℃, 28 ℃, 30 ℃, 32 ℃ or 35 ℃, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.
Preferably, the pre-dip time is 10 to 60s, preferably 20 to 50s, and may be, for example, 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s, or 60s, but is not limited to the recited values, and other values not recited within the range of values are also applicable.
Preferably, the activation in step (3) comprises soaking in an activation solution, taking out, and washing with deionized water.
Preferably, the activating solution contains ionic palladium or colloidal palladium.
Preferably, the ionic palladium concentration in the activation solution is 50-200ppm, preferably 100-150ppm, and may be, for example, 50ppm, 70ppm, 90ppm, 100ppm, 110ppm, 130ppm, 150ppm, 170ppm, 190ppm or 200ppm, but is not limited to the recited values, and other unrecited values within the range of values are also applicable.
Preferably, the concentration of colloidal palladium in the activation solution is 15to 90ppm, preferably 30 to 60ppm, and may be, for example, 15ppm, 30ppm, 45ppm, 60ppm, 75ppm or 90ppm, but is not limited to the recited values, and other values not recited within the range of values are also applicable.
Preferably, the temperature of the activation in step (3) is 35-60 ℃, preferably 45-55 ℃, for example 35 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃ or 60 ℃, but is not limited to the recited values, and other values not recited in the range of values are equally applicable.
Preferably, the activation time in step (3) is 30-120s, preferably 50-80s, and may be, for example, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, or 120s, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.
Preferably, the post-activation treatment in step (3) includes soaking in the post-activation treatment solution, taking out, and washing with deionized water.
The step of "post-activation treatment" in the present invention refers to activation reduction or rapid activation, and when an ionic palladium activation solution is used in the previous activation step, the subsequent step is an activation reduction step, and when a colloidal palladium activation solution is used in the previous activation step, the subsequent step is a rapid activation step, which is also called a degumming step.
Preferably, the temperature of the post-activation treatment is 30 to 40 ℃, preferably 32 to 35 ℃, and may be, for example, 30 ℃, 32 ℃, 35 ℃, 38 ℃ or 40 ℃, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.
Preferably, the post-activation treatment is carried out for a period of time of 20 to 90s, preferably 40 to 60s, and may be, for example, 20s, 30s, 40s, 50s, 60s, 70s, 80s or 90s, but is not limited to the recited values, and other values not recited within the range of values are also applicable.
As a preferable technical scheme of the invention, the electroless copper plating in the step (3) comprises soaking in an electroless copper plating solution, taking out, washing with deionized water and drying.
Preferably, the electroless copper plating temperature is 28-40 ℃, preferably 30-37 ℃, for example 28 ℃, 30 ℃, 32 ℃, 35 ℃, 38 ℃ or 40 ℃, but is not limited to the recited values, and other values not recited in the range of values are equally applicable.
Preferably, the electroless copper plating time is 3-20min, for example, 3min, 5min, 6min, 8min, 10min, 13min, 15min, 16min, 18min or 20min, but is not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the surface conditioner treated region in step (5) includes a resin region and a glass fiber region, resulting in a structured sheet.
Preferably, the surface conditioner comprises any one of or a combination of at least two of dimethylformamide, cetylammonium chloride, alkylphenol polyoxyethylene or alkyltrimethylchloroalkane.
And in the neutralization step, a surface conditioning agent is used, so that the glass fiber and resin composite material generates static electricity in the high-speed operation process of the drill bit, the surface conditioning agent adjusts the negative polarity of the resin surface to enhance the adsorption of the glass fiber surface conditioning agent, and inorganic groups at two ends are adjusted to be adsorbed with the glass fiber inorganic groups.
Preferably, the temperature of neutralization is from 30 to 60 ℃, preferably from 35 to 45 ℃, and may be, for example, 30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃ or 60 ℃, but is not limited to the recited values, and other unrecited values within the range of values are equally applicable.
Preferably, the neutralization time is 30 to 150s, preferably 60 to 100s, and may be, for example, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, 120s, 130s, 140s or 150s, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.
In a preferred embodiment of the present invention, the pickling in steps (4) and (6) includes cleaning the surface oxide layer in a pickling solution and then removing the surface oxide layer.
Preferably, the acid wash comprises dilute sulfuric acid.
Preferably, the dilute sulfuric acid has a concentration of 3to 5 wt.%, and may be, for example, 3 wt.%, 3.2 wt.%, 3.5 wt.%, 3.8 wt.%, 4 wt.%, 4.2 wt.%, 4.5 wt.%, 4.8 wt.%, or 5 wt.%, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.
Preferably, the acid washing temperature is 15-35 deg.C, preferably 20-30 deg.C, and may be, for example, 15 deg.C, 18 deg.C, 20 deg.C, 22 deg.C, 25 deg.C, 28 deg.C, 30 deg.C, 32 deg.C or 35 deg.C, but is not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the acid wash time is 5-15s, for example, 5s, 8s, 10s, 12s or 15s, but not limited to the recited values, and other values not recited within this range are equally applicable.
As a preferred technical solution of the present invention, the oil removal in steps (4) and (6) includes removing surface oil and an oxide layer in an oil removal agent, taking out, and washing with deionized water.
Preferably, the degreasing temperature is 25-35 ℃, preferably 28-32 ℃, for example 25 ℃, 28 ℃, 30 ℃, 32 ℃ or 35 ℃, but not limited to the recited values, and other values not recited in the range of values are equally applicable.
Preferably, the degreasing time is 20 to 60s, preferably 30 to 40s, and may be, for example, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s, or 60s, but is not limited to the recited values, and other values not recited in the range of values are also applicable.
As a preferred embodiment of the present invention, the method comprises the steps of:
(1) baking the plate: baking the mixed-compression circuit board in baking equipment at the temperature of 100-150 ℃ for 20-300min to obtain a dry board, wherein all steps after the step (1) are finished within 4 h;
(2) plasma cleaning and activating: vacuumizing the dried plate to 0.05-0.15torr in plasma equipment, introducing clean gas to keep the pressure at 0.2-0.3torr, carrying out plasma cleaning for 15-25min, introducing activated gas to keep the pressure at 0.2-0.3torr, and carrying out plasma activation for 35-45 min;
(3) chemical hole plating: soaking the pretreated sheet in a pore-forming solution at 40-60 ℃ for 30-150s, taking out, washing with deionized water, soaking in an acidic microetching solution at 25-35 ℃ for 30-60s, thinning the plated layer of the sheet after pore forming for 0.3-1.5 mu m, washing with deionized water, soaking in a pre-soaking solution at 15-35 ℃ for 10-60s, taking out, soaking in a pre-soaking solution containing 50-200ppm ionic palladium or 15-90ppm colloidal palladium, soaking in 35-60 deg.C activating solution for 30-120s, washing with deionized water, soaking in 30-40 deg.C activating solution for 20-90s, washing with deionized water, soaking in 28-40 deg.C electroless copper plating solution for 3-20min, washing with deionized water, and drying;
(4) primary electroplating: removing surface grease and an oxide layer from the plate treated in the step (3) in an oil removing agent at 25-35 ℃, taking out after 20-60s, washing the plate with deionized water, cleaning the surface oxide layer in dilute sulfuric acid at 3-5 wt% and 15-35 ℃ for 5-15s, taking out, and electrifying the electroplated copper solution to thicken the plating layer by 3-5 microns;
(5) neutralizing: adjusting resin and glass fiber areas of the board subjected to the primary copper electroplating by using a surface modifier to obtain a regular board;
repeating the step (3) once for the structured plate;
(6) secondary electroplating: and (3) removing surface grease and an oxidation layer from the plate processed in the step (3) in a degreasing agent at 25-35 ℃, taking out after 20-60s, washing with deionized water, cleaning the surface oxidation layer in dilute sulfuric acid at 3-5 wt% and 15-35 ℃ for 5-15s, taking out, and electrifying the electroplating copper solution to thicken the plating layer by 5-30 mu m to obtain the hole-metallized mixed-pressure circuit board.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the method for metallizing the holes of the mixed-pressure circuit board, the problem of the bonding force between the electroplated copper and the surface copper can be effectively avoided by adding the step of activating the plasma;
(2) the invention changes the hole plating procedure from one to two in the traditional procedure, the first electroplating copper adopts a flash plating process, and the plating layer only thickens 3-5 mu m, so that the refined operation can protect the copper layer of the special material area from being corroded, and further the uniform plating layer in the hole and the good combination between the dielectric layers of the glass fiber area and the filler area are ensured;
(3) in the neutralization step, the surface conditioning agent is used, so that the charges of the inorganic material area and the glass fiber area are adjusted, the deposition of copper in the second electroless copper plating is facilitated, and the plating leakage phenomenon of the mixed pressing area is further avoided.
Drawings
Fig. 1 is a schematic view of a press-fit structure of a mixed-pressure circuit board used in embodiment 1 of the present invention.
Wherein, 1, PTFE layer; 2. a filler layer; 3. a back glue layer; 4. and a copper foil layer.
Detailed Description
For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
In one embodiment, the present invention provides a method for hole metallization of a hybrid circuit board, comprising the steps of:
(1) baking the plate: baking the mixed-compression circuit board in baking equipment at the temperature of 100-150 ℃ for 20-300min to obtain a dry board, wherein all steps after the step (1) are finished within 4 h;
(2) plasma cleaning and activating: vacuumizing the dried plate to 0.05-0.15torr in plasma equipment, introducing clean gas to keep the pressure at 0.2-0.3torr, carrying out plasma cleaning for 15-25min, introducing activated gas to keep the pressure at 0.2-0.3torr, and carrying out plasma activation for 35-45 min;
(3) chemical hole plating: soaking the pretreated sheet in a pore-forming solution at 40-60 ℃ for 30-150s, taking out, washing with deionized water, soaking in an acidic microetching solution at 25-35 ℃ for 30-60s, thinning the plated layer of the sheet after pore forming for 0.3-1.5 mu m, washing with deionized water, soaking in a pre-soaking solution at 15-35 ℃ for 10-60s, taking out, soaking in a pre-soaking solution containing 50-200ppm ionic palladium or 15-90ppm colloidal palladium, soaking in 35-60 deg.C activating solution for 30-120s, washing with deionized water, soaking in 30-40 deg.C activating solution for 20-90s, washing with deionized water, soaking in 28-40 deg.C electroless copper plating solution for 3-20min, washing with deionized water, and drying;
(4) primary electroplating: removing surface grease and an oxide layer from the plate treated in the step (3) in an oil removing agent at 25-35 ℃, taking out after 20-60s, cleaning the surface oxide layer in dilute sulfuric acid at 15-35 ℃ for 5-15s at 3-5 wt%, taking out, washing with deionized water, and electrifying the electroplated copper solution to thicken the plating layer by 3-5 microns;
(5) neutralizing: adjusting resin and glass fiber areas of the plated plate by a cationic surface modifier to obtain a regular plate;
repeating the step (3) once for the structured plate;
(6) secondary electroplating: removing surface grease and an oxide layer in the degreaser at the temperature of 25-35 ℃ after the treatment in the step (3) is repeated, taking out after 20-60s, washing the board by using deionized water, cleaning the surface oxide layer in dilute sulfuric acid at the temperature of 15-35 ℃ for 5-15s, taking out, and electrifying the electroplating copper solution to thicken the plating layer by 5-30 mu m to obtain the hole-metalized mixed-pressure circuit board.
It is understood that processes or substitutions and variations of conventional data provided by embodiments of the present invention are within the scope and disclosure of the present invention.
Example 1
The embodiment provides a method for metallizing holes of a mixed-compression circuit board, which is used for metallizing holes of an AD255 mixed-compression antenna circuit board produced by Rogers company, wherein the mixed-compression antenna circuit board is a soft-hard combined board with the size of 6cm multiplied by 10cm, a pressing structure of the mixed-compression antenna circuit board is shown in figure 1, and the mixed-compression antenna circuit board sequentially comprises a copper foil layer, a gum layer, a packing layer, a PTFE layer, the packing layer, the gum layer and the copper foil layer from top to bottom, and the method comprises the following steps:
(1) baking the plate: baking the mixed-compression antenna circuit board in baking equipment at 120 ℃ for 120min to obtain a dried board, wherein all steps after the step (1) are finished within 4 h;
(2) plasma cleaning and activating: vacuumizing the dried plate to 0.1torr in plasma equipment, introducing mixed gas of oxygen, nitrogen and carbon tetrafluoride, keeping the pressure at 0.25torr, carrying out plasma cleaning for 20min, introducing oxygen, keeping the pressure at 0.25torr, and carrying out plasma activation for 40 min;
(3) chemical hole plating: the pretreated plate is subjected to pore-aligning treatment for 90s in pore-aligning liquid prepared by oil removing agent Skyclean 321C produced by SkyChem company at 50 ℃ and with the concentration of 40ml/L, and then is washed for 1min by deionized water; then carrying out microetching in an acidic microetching solution prepared from 100g/L sodium persulfate and 50g/L sulfuric acid at the temperature of 28 ℃, and washing the plated layer of the plate after hole trimming for 1min by using deionized water after the plated layer is thinned by 0.3-1.5 mu m; then, the pre-soaking agent SkyCat 330C manufactured by SkyChem company is pre-soaked for 20s in pre-soaking liquid prepared by the concentration of 10ml/L at the temperature of 28 ℃; then activating the activated solution for 30-120s in an activating solution prepared by an ionic palladium activating agent SkyCat 335C produced by SkyChem corporation at 50 ℃ and with the concentration of 200ml/L (the concentration of palladium ions is 100ppm), and washing the activated solution for 1min by using deionized water; then, the mixture is washed by deionized water after being activated and reduced for 40s in activated and reduced solution which is prepared by activating and reducing agent SkyCat 336R produced by SkyChem company at 35 ℃ and with the concentration of 10 ml/L; then plating in SkyCopp 365 chemical copper plating solution produced by SkyChem company at 34 ℃ for 6min, washing with deionized water for 1min and drying with hot air;
(4) primary electroplating: removing surface grease and an oxide layer from the plate treated in the step (3) in a SkyClean608C degreasing agent at 30 ℃, washing the plate for 40 seconds by using deionized water for 1min, cleaning the surface oxide layer in dilute sulfuric acid at 25 ℃ and 4 wt% for 10 seconds, taking out the plate, and electrifying the plate to electroplate to thicken the plating layer by 4 microns;
(5) neutralizing: adjusting resin and glass fiber areas of the plated plate by using a cationic surface modifier with the concentration of 40ml/L, wherein the neutralizer SkySecure 312C produced by SkyChem company is used for adjusting the resin and glass fiber areas at 50 ℃ to obtain a structured plate;
repeating the step (3) once for the structured plate;
(6) secondary electroplating: and (3) removing surface grease and an oxide layer from the plate processed in the step (3) in a degreasing agent at 25-35 ℃, taking out after 20-60s, washing with deionized water, cleaning the surface oxide layer in dilute sulfuric acid at 25 ℃ and 4 wt% for 10s, taking out, and electrifying the electroplating copper solution to thicken the plating layer by 30 mu m to obtain the hole-metallized soft-hard combined plate.
Example 2
The embodiment provides a method for metallizing holes of a mixed-compression circuit board, which is used for metallizing holes of a 6035HTC mixed-compression antenna circuit board manufactured by Rogers company, wherein the mixed-compression antenna circuit board is a polytetrafluoroethylene-glass felt laminated board with the size of 6cm × 10cm, and the method comprises the following steps:
(1) baking the plate: baking the mixed-compression antenna circuit board in baking equipment at 150 ℃ for 20min to obtain a dried board, wherein all steps after the step (1) are finished within 4 h;
(2) plasma cleaning and activating: vacuumizing the dried plate to 0.15torr in plasma equipment, introducing mixed gas of argon, nitrogen and carbon tetrafluoride, keeping the pressure at 0.3torr, carrying out plasma cleaning for 15min, introducing nitrogen, keeping the pressure at 0.3torr, and carrying out plasma activation for 35 min;
(3) chemical hole plating: the pretreated plate is subjected to pore-aligning for 150s in pore-aligning liquid prepared by oil removing agent Skyclean 321C produced by SkyChem company at 40 ℃ and with the concentration of 40ml/L, and then is washed for 1min by deionized water; then carrying out microetching in an acidic microetching solution prepared from 100g/L sodium persulfate and 50g/L sulfuric acid at the temperature of 28 ℃, and washing the plated layer of the plate after hole trimming for 1min by using deionized water after the plated layer is thinned by 0.3-1.5 mu m; then, the substrate was presoaked for 120 seconds in a presoaking solution prepared at a concentration of 200g/l from a presoaking agent SkyCat3391S manufactured by SkyChem corporation at 15 ℃; then activated for 120 seconds in an activation solution prepared by a colloidal palladium activator SkyCat3396J produced by SkyChem corporation at 35 ℃ and having a concentration of 50ml/L (palladium ion concentration is 50ppm), and washed for 1min with deionized water; then activating and reducing the solution for 90s in accelerating solution prepared by accelerating agent SkyCat3398 produced by SkyChem company at the concentration of 10ml/l at the temperature of 35 ℃ and washing the solution by using deionized water; then plating in SkyCopp 365 chemical copper plating solution produced by SkyChem company at 28 ℃ for 20min, washing with deionized water for 1min, and drying with hot air;
(4) primary electroplating: removing surface grease and an oxide layer from the plate treated in the step (3) in a SkyClean608C degreasing agent at 25 ℃, washing the plate for 40 seconds by using deionized water for 1min, cleaning the surface oxide layer in dilute sulfuric acid at 35 ℃ and 5 wt% for 10 seconds, taking out the plate, and electrifying the plate to electroplate to thicken the plating layer by 3 mu m;
(5) neutralizing: the plate after the hole plating is subjected to cationic surface conditioning agent with the concentration of 25ml/L and prepared by neutralizing agent SkySecure 310C produced by SkyChem company at 30 ℃, resin and glass fiber area are adjusted for 60s, and the structured plate is obtained;
repeating the step (3) once for the structured plate;
(6) secondary electroplating: and (3) removing surface grease and an oxide layer from the plate processed in the step (3) in a SkyClean608C degreasing agent at 25 ℃, washing the plate for 40 seconds by using deionized water for 1min, washing the surface oxide layer in dilute sulfuric acid at 35 ℃ and 5 wt% for 10 seconds, taking out the plate, and electrifying the electroplating copper solution to thicken the plating layer by 25 mu m to obtain the hole metallized polytetrafluoroethylene-glass felt laminated plate.
Example 3
The embodiment provides a method for metallizing holes of a mixed-compression circuit board, which is used for metallizing holes of an RF35HTC antenna circuit board manufactured by Taconic corporation, wherein the antenna circuit board is a double-layer polyimide soft board and has the size of 6cm multiplied by 10cm, and the method comprises the following steps:
(1) baking the plate: baking the mixed-compression antenna circuit board in baking equipment at 100 ℃ for 300min to obtain a dried board, wherein all steps after the step (1) are finished within 4 h;
(2) plasma cleaning and activating: vacuumizing the dried plate to 0.05torr in plasma equipment, introducing mixed gas of oxygen, nitrogen and carbon tetrafluoride, keeping the pressure at 0.2torr, carrying out plasma cleaning for 25min, introducing oxygen, keeping the pressure at 0.2torr, and carrying out plasma activation for 45 min;
(3) chemical hole plating: the pretreated plate is subjected to pore-aligning for 30s in pore-aligning liquid prepared by oil removing agent Skyclean 321C produced by SkyChem company at 60 ℃ and with the concentration of 40ml/L, and then is washed for 1min by deionized water; then carrying out micro-etching in an acidic micro-etching solution prepared from 100g/L sodium persulfate and 50g/L sulfuric acid at 35 ℃, thinning the plated layer of the plate after hole finishing by 0.3-1.5 mu m, and washing for 1min by using deionized water; then presoaking for 10s in presoaking liquid prepared by presoaking agent SkyCat 330C produced by SkyChem company at 35 ℃ and with the concentration of 10 ml/L; then activated for 30 seconds in an activation solution prepared by an ionic palladium activator SkyCat 335C produced by SkyChem corporation at 50 ℃ and having a concentration of 400ml/L (the concentration of palladium ions is 200ppm), and washed for 1min by deionized water; then activated and reduced for 20s in activated and reduced solution prepared by activated and reduced agent SkyCat 336R manufactured by SkyChem corporation at the temperature of 40 ℃ and with the concentration of 10ml/L, and then washed by deionized water; then plating in SkyCopp 365 chemical copper plating solution produced by SkyChem company at 28 ℃ for 20min, washing with deionized water for 1min, and drying with hot air;
(4) primary electroplating: removing surface grease and an oxide layer from the plate treated in the step (3) in a SkyClean608C degreasing agent at 30 ℃, washing the plate for 40 seconds by using deionized water for 1min, cleaning the surface oxide layer for 5 seconds in dilute sulfuric acid at 35 ℃ and 5 wt%, taking out the plate, and electrifying the plate to electroplate to thicken the plating layer by 5 microns;
(5) neutralizing: adjusting resin and glass fiber areas of the plated plate by using a cationic surface modifier with the concentration of 40ml/L, wherein the neutralizer SkySecure 312C produced by SkyChem company is used for adjusting the resin and glass fiber areas at 50 ℃ to obtain a structured plate;
repeating the step (3) once for the structured plate;
(6) secondary electroplating: and (3) removing surface grease and an oxide layer from the plate processed in the step (3) in a SkyClean608C degreasing agent at 30 ℃, washing the plate for 40 seconds by using deionized water for 1min, washing the surface oxide layer for 5 seconds in dilute sulfuric acid at 35 ℃ and 5 wt%, taking out the plate, and electrifying the electroplating copper solution to thicken the plating layer by 5 microns to obtain the hole-metallized double-layer polyimide soft plate.
Example 4
This example is the same as example 1 for hole metallization, and provides substantially the same method as example 1 with the only difference that the first plating layer is thickened by 2 μm.
Example 5
This example is the same as example 1 for hole metallization, and provides substantially the same method as example 1 with the only difference that the first plating layer is thickened by 7.5 μm.
Comparative example 1
This comparative example provides a method of metallizing a hole of a wiring board using the hybrid antenna wiring board of example 1, the method of the embodiment in CN 108471680A.
Comparative example 2
This comparative example, a circuit board that was hole metallized, was the same as example 1 and provided a process substantially the same as example 1, with the only difference being that there was only a plasma cleaning step and no plasma activation step.
Comparative example 3
The comparative example, a circuit board with via metallization was the same as in example 1 and provided in substantially the same manner as in example 1, with the only difference being that the neutralization step used a sulfuric acid, hydrogen peroxide system plus a benzenesulfonic acid system.
The test was carried out on the boards which were hole-metallized by the methods of examples 1to 5 and comparative examples 1to 3, according to the following test methods:
the plate was cut into 3cm × 3cm pieces and subjected to a thermal shock reliability test. Thermal shock conditions: immersing tin at 288 deg.C for 10s times for 6 times. After thermal shock, the slices are made into slices to observe the copper plating condition in the holes and the plate surface binding force.
And (3) testing results: the plate treated by the method of the embodiment 1-3 has complete copper plating in holes, good binding force of a non-leakage plating plate surface, no separation of surface copper and a chemical copper plating layer and good plating layer after a thermal shock test; in the plate treated by the method in the embodiment 4, the flash plating layer is too thin, and the flash plating copper is corroded away after the secondary chemical copper passes through the micro-corrosion section, so that the risk of pitting is generated; the plate treated by the method in the embodiment 5 has the defects of excessive thickness of flash plating copper, thin requirement of secondary copper plating, difficult control of conditions and difficulty in etching circuits with small line width and line distance.
The plate treated by the method of the comparative example 1 has plating leakage phenomenon on the hole wall and the mixed pressing area, and the electroplated copper and the surface copper are cracked after a thermal shock test; the plate treated by the method of the comparative example 2 has the same appearance as the plate treated by the method of the examples 1to 3, but the electroplated copper and the surface copper are cracked after the thermal shock test; the plate treated by the method of comparative example 3 had a plating-missing phenomenon in the inorganic material region and the glass fiber region.
In summary, the mixed-pressure circuit board processed by the method for metallizing the holes of the mixed-pressure circuit board provided by the invention has the advantages that the phenomena of copper breaking and copper leakage do not occur in the holes and mixed-pressure areas, the plating layer is uniform, the bonding force between the electroplated copper and the surface copper on the surface of the board is good, the bonding between the mixed-pressure dielectric layers after the holes are metallized is stable, the method is improved on the basis of the existing process, a new production line is not needed to be added, the yield is improved only by adding and adjusting individual process steps, the investment is small, the return report is high, the method can be applied to various types of boards, and the method is suitable for large-scale industrial popularization.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (10)
1. A method of hybrid circuit board hole metallization, the method comprising the steps of:
(1) baking the plate: baking the mixed-pressing circuit board to obtain a dry plate;
(2) plasma cleaning and activating: the dried plate is sequentially subjected to vacuumizing, plasma cleaning and plasma activation to obtain a pretreated plate;
(3) chemical hole plating: sequentially carrying out hole trimming, microetching, presoaking, activating, post-activation treatment and chemical copper plating on the pretreated plate;
(4) primary electroplating: sequentially carrying out oil removal, acid cleaning and primary copper electroplating on the plate treated in the step (3);
(5) neutralizing: treating the plate subjected to the primary copper electroplating by using a surface conditioning agent to obtain a regular plate;
repeating the step (3) once for the structured plate;
(6) secondary electroplating: and (4) sequentially carrying out oil removal, acid cleaning and secondary copper electroplating on the board treated in the step (3) to obtain the hole-metallized mixed-compression circuit board.
2. The method of claim 1, wherein the thickness of the plating layer is increased by 3to 5 μm in the primary plating in the step (4);
preferably, the thickness of the plating layer is increased by 5to 30 μm in the secondary plating in the step (6).
3. The method according to claim 1 or 2, wherein all steps after step (1) are completed within 4 h;
preferably, the mixed-compression circuit board comprises any one or a combination of more than two of polyimide, polytetrafluoroethylene, glass fiber or filler;
preferably, the baking temperature is 100-150 ℃, preferably 120-130 ℃;
preferably, the baking time is 20-300min, preferably 120-240 min.
4. The method according to any one of claims 1to 3, wherein the plasma cleaning activation in step (2) comprises: vacuumizing the dried plate in plasma equipment to initial pressure, introducing cleaning gas, keeping the cleaning pressure for plasma cleaning after reaching the cleaning pressure, introducing activating gas, and keeping the activating pressure for plasma activation after reaching the activating pressure;
preferably, the starting pressure is 0.05to 0.15torr, preferably 0.08to 0.12 torr;
preferably, the cleaning gas includes a mixed gas of oxygen, nitrogen, carbon tetrafluoride and argon;
preferably, the total flow rate of the oxygen, nitrogen and carbon tetrafluoride is 2.3-2.8L/min;
preferably, the volume flow fraction of the oxygen is 60-90%;
preferably, the volume flow fraction of the nitrogen is 10-40%;
preferably, the volume flow fraction of the carbon tetrafluoride is 6 to 12%;
preferably, the flow rate of the argon gas is 1.0-1.8L/min;
preferably, the cleaning pressure is 0.2to 0.3torr, preferably 0.23to 0.28 torr;
preferably, the plasma cleaning time is 15-25min, preferably 18-22 min;
preferably, the activating gas comprises any one or a combination of two or more of helium, nitrogen or oxygen;
preferably, the pressure of the activation is 0.2to 0.3torr, preferably 0.23to 0.28 torr;
preferably, the plasma activation time is 35-45min, preferably 38-42 min.
5. The method according to any one of claims 1to 4, wherein the pore-forming in step (3) comprises soaking in a pore-forming solution, removing, and washing with deionized water;
preferably, the temperature of the whole hole is 40-60 ℃, preferably 45-55 ℃;
preferably, the time for pore completion is 30 to 150s, preferably 60 to 100 s;
preferably, the microetching comprises soaking in a microetching solution, taking out, and washing with deionized water;
preferably, the microetching solution comprises an acidic microetching solution; preferably, the acidic microetching solution comprises sulfuric acid-sodium persulfate microetching solution or sulfuric acid-hydrogen peroxide microetching solution;
preferably, the sulfuric acid-persulfate microetching solution comprises a sulfuric acid solution;
preferably, the sulfuric acid-persulfate microetching solution also comprises sodium persulfate and/or ammonium persulfate;
preferably, the sulfuric acid-hydrogen peroxide microetching solution comprises a sulfuric acid solution and hydrogen peroxide;
preferably, the sulfuric acid-hydrogen peroxide microetching solution also comprises a hydrogen peroxide stabilizer;
preferably, the hydrogen peroxide stabilizer comprises at least one or a combination of more than two of ethanolamine, methane diamine or isooctyl amine;
preferably, the microetching temperature is 25-35 ℃, preferably 28-32 ℃;
preferably, the microetching time is 30 to 60s, preferably 40 to 50 s;
preferably, the microetching reduces the plating layer of the plate after the whole hole by 0.3-1.5 μm.
6. The method according to any one of claims 1to 5, wherein the pre-soaking in step (3) comprises taking out after soaking in a pre-dip solution;
preferably, the temperature of the presoaking is 15-35 ℃, preferably 20-30 ℃;
preferably, the presoaking time is 10 to 60s, preferably 20 to 50 s;
preferably, the activation in the step (3) comprises soaking in an activation solution, taking out, and washing with deionized water;
preferably, the activating solution contains ionic palladium or colloidal palladium;
preferably, the concentration of the ionic palladium in the activation solution is 50-200ppm, preferably 100-150 ppm;
preferably, the concentration of the colloidal palladium in the activating solution is 15-90ppm, preferably 30-60 ppm;
preferably, the temperature of the activation in step (3) is 35-60 ℃, preferably 45-55 ℃;
preferably, the activation time in step (3) is 30 to 120s, preferably 50 to 80 s;
preferably, the post-activation treatment in the step (3) comprises soaking in the post-activation treatment solution, taking out, and washing with deionized water;
preferably, the temperature of the post-activation treatment is 30-40 ℃, preferably 32-35 ℃;
preferably, the time of the post-activation treatment is 20 to 90s, preferably 40 to 60 s.
7. The method according to any one of claims 1to 6, wherein the electroless copper plating in step (3) comprises taking out after soaking in an electroless copper plating solution, washing with deionized water and drying;
preferably, the temperature of the electroless copper plating is 28-40 ℃, preferably 30-37 ℃;
preferably, the electroless copper plating time is 3-20 min;
preferably, the area treated by the surface modifier in the step (5) comprises a resin area and a glass fiber area, so that the structured board is obtained;
preferably, the temperature of neutralization is 30-60 ℃, preferably 35-45 ℃;
preferably, the time of neutralization is from 30 to 150s, preferably from 60 to 100 s.
8. The method of any one of claims 1-7, wherein the pickling in steps (4) and (6) comprises removing after cleaning the surface oxide layer in a pickling solution;
preferably, the acid wash comprises dilute sulfuric acid;
preferably, the concentration of the dilute sulfuric acid is 3-5 wt%;
preferably, the temperature of the acid washing is 15-35 ℃, preferably 20-30 ℃;
preferably, the time for pickling is 5to 15 s.
9. The method according to any one of claims 1to 8, wherein the oil removal in steps (4) and (6) comprises removing surface oil and an oxide layer in an oil removal agent, then taking out, and washing with deionized water;
preferably, the temperature for removing the oil is 25-35 ℃, preferably 28-32 ℃;
preferably, the time for degreasing is 20-60s, preferably 30-40 s.
10. Method according to any of claims 1-9, characterized in that the method comprises the steps of:
(1) baking the plate: baking the mixed-compression circuit board in baking equipment at the temperature of 100-150 ℃ for 20-300min to obtain a dry board, wherein all steps after the step (1) are finished within 4 h;
(2) plasma cleaning and activating: vacuumizing the dried plate to 0.05-0.15torr in plasma equipment, introducing clean gas to keep the pressure at 0.2-0.3torr, carrying out plasma cleaning for 15-25min, introducing activated gas to keep the pressure at 0.2-0.3torr, and carrying out plasma activation for 35-45 min;
(3) chemical hole plating: soaking the pretreated sheet in a pore-forming solution at 40-60 ℃ for 30-150s, taking out, washing with deionized water, soaking in an acidic microetching solution at 25-35 ℃ for 30-60s, thinning the plated layer of the sheet after pore forming for 0.3-1.5 mu m, washing with deionized water, soaking in a pre-soaking solution at 15-35 ℃ for 10-60s, taking out, soaking in a pre-soaking solution containing 50-200ppm ionic palladium or 15-90ppm colloidal palladium, soaking in 35-60 deg.C activating solution for 30-120s, washing with deionized water, soaking in 30-40 deg.C activating solution for 20-90s, washing with deionized water, soaking in 28-40 deg.C electroless copper plating solution for 3-20min, washing with deionized water, and drying;
(4) primary electroplating: removing surface grease and an oxide layer from the plate treated in the step (3) in an oil removing agent at 25-35 ℃, taking out after 20-60s, washing the plate with deionized water, cleaning the surface oxide layer in dilute sulfuric acid at 3-5 wt% and 15-35 ℃ for 5-15s, taking out, and electrifying the electroplated copper solution to thicken the plating layer by 3-5 microns;
(5) neutralizing: adjusting resin and glass fiber areas of the board subjected to the primary copper electroplating by using a surface modifier to obtain a regular board;
repeating the step (3) once for the structured plate;
(6) secondary electroplating: and (3) removing surface grease and an oxidation layer from the plate processed in the step (3) in a degreasing agent at 25-35 ℃, taking out after 20-60s, washing with deionized water, cleaning the surface oxidation layer in dilute sulfuric acid at 3-5 wt% and 15-35 ℃ for 5-15s, taking out, and electrifying the electroplating copper solution to thicken the plating layer by 5-30 mu m to obtain the hole-metallized mixed-pressure circuit board.
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