CN117979563A

CN117979563A - Processing method of high-precision circuit

Info

Publication number: CN117979563A
Application number: CN202410222836.XA
Authority: CN
Inventors: 罗练军; 罗文卓
Original assignee: Shenzhen Junzhuo Technology Co ltd
Current assignee: Shenzhen Junzhuo Technology Co ltd
Priority date: 2024-02-28
Filing date: 2024-02-28
Publication date: 2024-05-03

Abstract

The application discloses a processing method of a high-precision circuit, which comprises the following steps: copper deposition electroplating is carried out on the core plate; depositing a metal film on the copper layer; forming a metal pattern by laser etching the metal film, wherein the shape of the metal pattern is matched with the shape of the circuit pattern; etching the copper layer outside the metal pattern to form a circuit pattern covered by the metal pattern; and removing the metal film. According to the processing method of the high-precision circuit, provided by the application, the metal film is adopted to replace a mask layer of a dry film or a wet film in the prior art, so that dust interference in an exposure environment is avoided, and the circuit etching precision is improved.

Description

Processing method of high-precision circuit

Technical Field

The invention relates to the field of circuit forming of a PCB or a carrier plate, in particular to a processing method of a high-precision circuit.

Background

In the prior art, a method for forming a circuit pattern in a PCB core board comprises the steps of firstly forming a global electroplated copper layer, then pasting a dry film or a wet film on the copper layer, and then sequentially exposing and developing to form a mask layer of the circuit pattern; and etching to remove the exposed copper layer, removing the dry film, and etching the part covered by the dry film to remove the film to form the circuit pattern.

The dry film or wet film capable of sensitization used in the existing line pattern forming process needs to be formed by adopting specific film coating and film pressing equipment, and the cost of the film coating and film pressing equipment needs to be calculated in the line pattern forming process, so that the cost is increased. The operation precision of film coating and film pressing is limited, the thickness of a coated dry film or wet film is more than 15um, when a circuit pattern is a small-space small-size pattern, blind grooves exist between the dry films, etching liquid is not easy to enter, etching speed and effect are affected, the side etching quantity is large, etching factors are small, and the precision of the circuit pattern is affected. During the etching process, the etching liquid has etching effect not only downwards but also in the left and right directions, and side etching is unavoidable. The ratio of the etching depth to the undercut width is called the etching factor.

The existing circuit pattern forming process adopts an exposure process, the environmental impact is large, dust in the environment can shade the light path, the poor photo-curing of the photosensitive material is directly brought, and the circuit notch or open circuit defect is brought. In order to avoid environmental impact, the dust-free room is required to be used for exposure operation, and the dust-free room cannot stop the existence of dust and other impurities in the air, so that the cost is increased, and the influence of the environment on the exposure of the photosensitive film cannot be completely stopped. The existing circuit pattern forming process needs to adopt organic liquid to remove the dry film when removing the dry film, and the organic liquid after removing the dry film cannot be recovered, so that the discharge amount of the organic liquid and the treatment difficulty are increased.

Patent CN202111002461.9 discloses that an organic masking material is coated on the surface of a workpiece coated with copper foil, after copper deposition by drilling, a polymer film layer in a non-circuit area is removed by laser, the copper surface in the non-circuit area is exposed, and then a conductive pattern is prepared by chemical etching. In the technical scheme, the organic masking material has smaller hardness and poorer wear resistance, and is easy to cause phenomena of abrasion, breakage and the like of the masking material when the subsequent drilling copper deposition and metal protection layer deposition are carried out, so that the masking material layer can not be ensured to be still intact when the conductive pattern is prepared. Meanwhile, when the organic masking layer is removed by laser, the heat conduction performance of the organic masking layer is poor, so that the laser energy cannot be conducted timely, and the heat generated by the laser cannot be dissipated timely, so that the organic masking layer or the copper foil at the lower layer can deform at high temperature, and the precision deviation of a circuit pattern is caused.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the problems in the related art. Therefore, the invention aims to provide a processing method of a high-precision circuit, which adopts a metal film as a masking layer, adopts an alloy layer as a metal film, has good thermal conductivity, can timely dissipate heat generated by laser, avoids deformation of the metal film and a copper layer at high temperature, has high hardness and oxidation resistance, can be used as a protective layer of the copper layer at the same time, and improves the precision and efficiency of circuit pattern preparation.

In order to achieve the above purpose, the present application adopts the following technical scheme:

a processing method of a high-precision circuit comprises the following steps:

Copper deposition electroplating is carried out on the core plate;

depositing a metal film on the copper layer; the metal film comprises the following components in parts by weight: 99 parts of tin, 0.02-0.05 part of gold and 0.7-0.9 part of copper;

Forming a metal pattern by laser etching the metal film, wherein the shape of the metal pattern is matched with the shape of the circuit pattern;

etching the copper layer outside the metal pattern to form a circuit pattern covered by the metal pattern;

And removing the metal film.

The application adopts the metal film to replace the dry film or wet film in the traditional process, and patterns the metal film by a laser etching method, and dust in the environment is directly broken down by laser in the process of etching the metal film by the laser, so that the defects of openings or gaps and the like are avoided. The metal film has higher density and porosity less than 0.1 percent, has good heat conductivity of about 210W/(m.k), and has good heat conductivity. In the subsequent laser etching metal film process, the good thermal conductivity can enable heat energy in the laser processing process to be rapidly transferred to other parts through the metal film, and meanwhile, the heat energy is emitted into the air in a convection mode, so that abnormal occurrence of material deformation and the like caused by heat accumulation is effectively prevented.

Further, the thickness of the metal film is 1 μm or less.

Compared with a dry film or a wet film, the thickness of the metal film is thinner, and when the exposed copper layer is etched, etching liquid medicine easily enters the copper layer, so that the etching process has higher etching factor and smaller side etching amount, and further, a circuit pattern with better precision is obtained; is especially suitable for small-size circuit patterns.

Further, depositing a metal film on the copper layer includes: coating film forming liquid on the copper layer, and forming a metal film by chemical deposition; the film forming liquid comprises a gold ion complexing agent, a tin antioxidant, a copper ion complexing agent, a divalent tin-containing compound, a gold-containing compound, a copper-containing compound and an additive.

Further, the additives include gold stabilizers, masking agents, brighteners, grain refiners, and pH buffers.

Further, the film forming temperature of the chemical deposition method is 60-70 ℃; in the film forming process, the core plate where the copper layer is positioned is soaked in film forming liquid, and inert gas is filled into the film forming liquid.

The heating temperature of the chemical deposition method in the film forming process is generally selected to be 50-80 ℃. The preferred heating temperature is preferably 60-70 ℃. The temperature values during the solvent evaporation process will affect the composition of the final formed metal film. Too high a temperature may increase the thermal stress of the metal film, which may affect the etching effect during the subsequent etching of the copper layer. Too low a temperature and the phase change limit the growth rate of the metal film. According to the application, inert gas can be filled into the film forming liquid, and the film forming liquid is stirred to improve the forming speed of the metal film, improve the binding force between the metal film and the copper layer, reduce the porosity of the metal film and the like. When the copper-containing layer core plate is immersed in the film forming liquid, inert gas may be filled into the film forming liquid, and the film forming liquid may be stirred.

Further, the hardness of the metal film is 92HRA or more.

The metal film has the characteristics of high surface hardness, wear resistance, oxidation resistance and the like. The hardness of the metal film is higher, and the metal film can be prevented from being scratched and scratched in the carrying process.

Further, when the metal film is laser etched to form a metal pattern, the metal film is laser overetched.

In the application, the metal film is positioned above the copper layer, and the processing depth can be monitored in real time in the laser etching process in a mode of laser reflection time difference. The thickness of the metal film is about 1 micrometer, and the etching depth is required to be ensured to be more than or equal to the thickness of the metal film in the laser etching process. For example, when the thickness of the metal film is 1 micron, the laser spot moves towards the next position when the laser etching depth is 2 microns by monitoring the laser reflection time difference. Thus, the over-etching phenomenon exists in the laser etching process. The exposed copper layer needs to be etched later, so that the over-etching does not affect the subsequent etching of the copper layer, and the etching speed of the laser is far higher than that of the etching solution, so that the etching of the copper layer can be accelerated. Meanwhile, the over etching can ensure that the metal film is completely removed, and the influence on the subsequent copper layer etching process is avoided. The laser etching speed is high, and the metal film is removed through overetching, so that the metal film above the circuit pattern can be completely removed, and the etching speed of the circuit pattern can be accelerated.

Further, the wave band of the laser is 230-260nm.

The laser adopts round or matrix light spots, the size of the light spots is within the range of 10-50um, and the design can be specifically carried out through regional formulation. Tin has excellent absorptivity to ultraviolet wave of 220-286nm, so that the laser band selects light beam of 230-260nm to etch metal film. The application adopts nanosecond laser (one time of 10 ns) to etch the metal film, and the laser spot overlapping rate is 1/2 in the etching process.

Further, removing the metal film by adopting film removing liquid; the film removing liquid comprises the following components in parts by weight: 1-9 parts of boric acid, 45-55 parts of hydrofluoric acid and 8-12 parts of nitric acid; 30-35 parts of deionized water.

At room temperature, soaking the core plate after etching to form the circuit pattern in the film removing liquid for a period of time, taking out and wiping to remove the metal film. Or directly coating the film removing liquid on the surface of the metal film for soaking for a period of time, and wiping to remove the metal film. The removal method can not generate organic waste liquid and avoid the subsequent waste liquid treatment process.

Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages: the preparation method of the circuit pattern comprises the following steps: copper deposition electroplating is carried out on the core plate; depositing a metal film on the copper layer, wherein the metal film comprises the following components in parts by weight: 99 parts of tin, 0.02-0.05 part of gold and 0.7-0.9 part of copper; forming a metal pattern by laser etching the metal film, wherein the shape of the metal pattern is matched with the shape of the circuit pattern; etching the copper layer outside the metal pattern to form a circuit pattern covered by the metal pattern; and removing the metal film. The metal film provided by the application is used as an alloy, has higher surface hardness and better oxidation resistance, can be used as a protective layer in the process of carrying the core plate, provides a protective shielding effect for the copper layer, ensures that the copper layer and the metal film still have better conformality even though the middle is processed by a plurality of processes in the process of carrying and moving the core plate, and ensures the accuracy of the preparation of subsequent circuit patterns.

Meanwhile, the metal film has good heat conductivity, and when the metal film is etched by subsequent laser, the good heat conductivity can enable heat energy in the laser processing process to be rapidly transferred to other parts through the metal film, and meanwhile, the heat energy is emitted into the air in a convection mode, so that abnormal occurrence of material deformation and the like caused by heat accumulation is effectively prevented, deformation of a masking layer or a copper layer caused by laser processing in the prior art is avoided, and the accurate size and shape of a metal pattern and a circuit pattern are ensured.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.

In the accompanying drawings:

fig. 1 is a flow chart of the preparation of the small-sized circuit in example 2.

Detailed Description

For a clearer understanding of technical features, objects and effects of the present invention, a detailed description of embodiments of the present invention will be made with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "rear", "upper", "lower", "left", "right", "longitudinal", "transverse", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", "tail", etc. are configured and operated in specific directions based on the directions or positional relationships shown in the drawings, and are merely for convenience of describing the present invention, not to indicate that the mechanism or element referred to must have specific directions, and thus should not be construed as limiting the present invention.

It should also be noted that unless explicitly stated or limited otherwise, terms such as "mounted," "connected," "secured," "disposed," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. When an element is referred to as being "on" or "under" another element, it can be "directly" or "indirectly" on the other element or one or more intervening elements may also be present. The terms "first," "second," "third," and the like are used merely for convenience in describing the present invention and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, whereby features defining "first," "second," "third," etc. may explicitly or implicitly include one or more such features. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, mechanisms, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

Example 1

A processing method of a high-precision circuit comprises the following steps:

Copper deposition electroplating is carried out on the core plate;

Depositing a metal film on the copper layer;

And removing the metal film.

The metal film comprises the following components in parts by weight: 99 parts of tin, 0.02-0.05 part of gold and 0.7-0.9 part of copper; forming a metal pattern by laser etching the metal film, wherein the shape of the metal pattern is matched with the shape of the circuit pattern; etching the copper layer outside the metal pattern to form a circuit pattern covered by the metal pattern; and removing the metal film. The metal film provided by the application is used as an alloy, has higher surface hardness and better oxidation resistance, can be used as a protective layer in the process of carrying the core plate, provides a protective shielding effect for the copper layer, ensures that the copper layer and the metal film still have better conformality even though the middle is processed by a plurality of processes in the process of carrying and moving the core plate, and ensures the accuracy of the preparation of subsequent circuit patterns.

Example 2

As shown in fig. 1, the method for processing a high-precision circuit provided by the application comprises the following steps:

S1: copper plating is carried out on the core plate.

The core plate refers to the surface of the core plate on which a circuit pattern needs to be formed; the copper layer can be formed by electroplating and copper deposition.

Specifically, an initial copper layer is firstly deposited horizontally during copper deposition, and can be formed by adopting methods such as chemical deposition and the like, so that the initial copper layer has a good binding force with the surface of the core plate; and electroplating the initial copper layer to form a complete copper layer, wherein the electroplated copper layer can be better bonded with the initial copper layer. The two-step copper deposition method can ensure that the copper layer has better binding force with the surface of the core plate and ensures the firmness of the copper layer; and the deposition rate of the copper layer can be improved, and the preparation efficiency of the circuit pattern can be improved.

The thickness of the copper layer formed in the application can be limited according to the application scene of the circuit pattern and the design requirement. After the portions of the copper layer not requiring the formation of the wiring pattern are etched, the remaining portions of the copper layer form the wiring pattern.

S2: a metal film is deposited on the copper layer. The metal film comprises the following components in parts by weight: 99 parts of tin, 0.02-0.05 part of gold and 0.7-0.9 part of copper. The metal film is made of copper-containing gold-tin alloy, and has the characteristics of strong acid resistance, weak base resistance and the like as a special alloy layer.

In the present application, the metal film is formed by a chemical deposition method, an electroplating film formation method, or the like, and the finally formed alloy layer is not a mixture but an alloy simple substance with a changed lattice stacking form. The metal film has a thinner thickness, so that the deposition efficiency of the metal film can be improved, and the subsequent laser removal efficiency and accuracy can be improved.

Compared with a nonmetallic masking film, the metallic film can be used as a masking layer of a circuit pattern and can also be used as a protective layer of the core board in the carrying process. Compared with a carbon chain connecting structure in a high polymer masking film, the metal film is formed by stacking metal lattices, and has higher hardness and wear resistance.

The metal film is used as an alloy, contains copper and gold with poor chemical activity, and the gold and the copper are filled in tin lattices, so that the oxidation resistance of the metal film can be greatly improved, and the metal film can protect a copper layer and a core plate in the core plate carrying process.

The thickness of the metal film is less than or equal to 1 micrometer, and the purpose of protecting the residual copper layer is achieved only in the process of etching the copper layer. And the deposited metal film has smaller thickness, and under the condition of the thickness, etching liquid is easy to enter the copper layer for etching due to the smaller thickness after the metal film is removed by laser, so that the etching process of the copper layer has higher etching factor and smaller side etching amount, and further, a circuit pattern with better precision is obtained. Meanwhile, the thickness of the metal film is smaller, so that the uniformity of the metal film is better, and in the thinner metal film, the extremely poor thickness of each part is smaller, so that the uniformity tolerance is smaller. In the process of removing the metal film by subsequent laser processing, the metal film can be uniformly removed at one time by adopting the laser parameters with fixed parameters, so that the defect that the laser etching effects at different positions are different due to the fact that the uniformity tolerance of the metal film is large is avoided, and the defect that the laser parameters need to be changed frequently for the metal film with different uniformity, and even reworking is avoided after one time of laser etching.

The metal film has higher density, porosity less than 0.1 percent, surface hardness more than or equal to 92HRA, and has the characteristics of wear resistance, oxidation resistance and the like. The hardness of the metal film is higher, and the metal film can be prevented from being scratched and scratched in the carrying process.

The metal film is used as an alloy, contains copper and gold with higher heat conductivity, and the gold and the copper are filled in tin lattices, so that the heat conductivity of the metal film can be greatly improved. Therefore, the metal film of the present application has a good thermal conductivity of about 210W/(m.k), and has a good thermal conductivity. In the subsequent laser etching metal film process, the good thermal conductivity can enable heat energy in the laser processing process to be rapidly transferred to other parts through the metal film, and meanwhile, the heat energy is emitted into the air in a convection mode, so that abnormal occurrence of material deformation and the like caused by heat accumulation is effectively prevented.

The metal film comprises the following components in parts by weight: 99 parts of tin, 0.02-0.05 parts of gold, 0.7-0.9 parts of copper and 0.1 parts of other impurities, wherein the other impurities refer to other conductive metal or semiconductor doped impurities and the like.

The deposition method of the metal film in the present application may be formed by chemical deposition, electroplating film formation, or the like. The chemical deposition method specifically refers to CBD (chemical water bath deposition), which is a technique for depositing a film on the surface of a substrate material by using chemical reaction or electrochemical principles.

As a specific example, the electroless deposition method for forming a metal film specifically includes: and immersing the core plate after the copper layer is deposited in a film forming liquid, and heating a container containing the film forming liquid in a water bath to enable the film forming liquid to grow and separate out on the surface of the copper layer, so as to form a metal film.

Specifically, the heating temperature of the chemical deposition method in the film forming process is generally selected to be 50-80 ℃. The preferred heating temperature is preferably 60-70 ℃. The temperature values during the solvent evaporation process will affect the composition of the final formed metal film. Too high a temperature may increase the thermal stress of the metal film, which may affect the etching effect during the subsequent etching of the copper layer. Too low a temperature and the phase change limit the growth rate of the metal film.

According to the application, inert gas can be filled into the film forming liquid, and the film forming liquid is stirred to improve the forming speed of the metal film, improve the binding force between the metal film and the copper layer, reduce the porosity of the metal film and the like. When the copper-containing layer core plate is immersed in the film forming liquid, inert gas may be filled into the film forming liquid, and the film forming liquid may be stirred.

The film forming liquid comprises a gold ion complexing agent, a tin antioxidant, a copper ion complexing agent, a divalent tin-containing compound, a gold-containing compound, a copper-containing compound and an additive. On the basis of the components of the film forming liquid, the chemical deposition temperature of 50-80 ℃ is selected, meanwhile, inert gas is filled into the film forming liquid in the chemical deposition process, and the film forming liquid is stirred. Under the action of the components of the film forming liquid and film forming conditions, the binding force between the metal film and the copper layer can be improved, and the porosity of the metal film can be reduced; finally, the metal film with higher density, porosity less than 0.1%, surface hardness more than or equal to 92HRA, wear resistance, oxidation resistance and the like is formed.

As another specific example, a metal film may be formed on the copper layer by a method of electroplating a film-forming liquid. Specifically, a core plate deposited with a copper layer is used as a cathode, so that metal ions in the film forming liquid are electroplated outside the copper layer. In the electroplating process, the positions of the copper layer can be clamped through the conductive clamping pieces, so that the electric potential at the positions is equal, and then the metal film is uniformly electroplated at the positions on the surface of the copper layer, so that a metal film layer with uniform thickness is formed.

The film forming liquid comprises a gold ion complexing agent, a tin antioxidant, a copper ion complexing agent, a divalent tin-containing compound, a gold-containing compound, a copper-containing compound and an additive.

Gold ion complexing agent: sulfurous acid, thiosulfate, pyrophosphoric acid, citric acid and their potassium, sodium, ammonia, alkaline earth metal salts can be selected as gold ion complexing agents. The gold ion complexing agent can not only improve the stability of the film forming liquid, but also buffer the pH value and increase the brightness of the metal film layer so as to improve the adhesion between the metal and the copper layer.

Tin ion complexing agent: the amphoteric acid or alkali of the simple substance tin can carry out complexation reaction with tin, and oxalic acid, citric acid, ascorbic acid, glucose, malonic acid, iminodiacetic acid and the like can be specifically selected as complexing agents of bivalent tin ions. In an acidic solution, the stannous reacts with water in a hydration way, and tetravalent stannum is unstable; under alkaline conditions, tetravalent tin is stable, and stannous is easy to undergo disproportionation reaction. The tin complex is relatively stable in a neutral solution, so that the pH value of the film forming liquid can be regulated to be about 7.

Tin antioxidant: since stannous is oxidized into tetravalent stannum in the solution to cause the problem that stannum cannot be deposited, an antioxidant or a reducing agent is added into the solution to improve the stability of the stannous, and the selected stannum antioxidant is a hydroxybenzene compound.

Copper ion complexing agent: sulfuric acid can be selected as a complexing agent for copper ions, forming a stable presence of copper sulfate.

Additive: other additives are properly added into the film forming liquid to ensure the electroplating performance of the plating liquid and the plating quality, including alloy stabilizer, masking agent, brightening agent, grain refiner, pH buffering agent, conductive salt, nitrogen doped graphene oxide and the like.

The film forming liquid contains the nitrogen doped graphene oxide, and the nitrogen doped graphene oxide is used as a catalyst, so that the potentials of tin, gold and copper ions in the film forming liquid are similar, the content of each metal ion in the film forming liquid is combined, the uniform deposition of each metal ion in a certain proportion is ensured, the metal film is ensured to be in an alloy form with consistent crystal lattice, and further, the metal film is ensured to have specific heat conducting property, uniformity, hardness and oxidation resistance.

The film forming liquid can ensure that the potential difference of tin ions, copper ions and gold ions is smaller in the film forming process, and three metal ions can be uniformly deposited on the surface of a copper layer according to a certain proportion, so that the metal film with thinner thickness, good heat conducting property, good uniformity, higher hardness and better oxidation resistance is finally formed.

S3: and forming a metal groove by laser etching the metal film, wherein the shape of the metal groove is matched with the shape of the circuit pattern, and the metal groove exposes the copper layer. The shape of the circuit pattern and the size of the copper layer can be input into a controller of the laser etching machine, and the controller automatically calculates the moving path of the laser beam in the laser etching process; and fixing the core board on which the copper layer and the metal film are deposited in a laser etching machine, and etching the metal film by using a laser beam along a preset moving path, so that the copper layer without forming a circuit pattern is exposed.

The laser parameters adopted by the application are as follows: the laser adopts round or matrix light spots, the size of the light spots is within the range of 10-50um, and the design can be specifically carried out through regional formulation. Tin has excellent absorptivity to ultraviolet wave of 220-286nm, so that the laser band selects light beam of 230-260nm to etch metal film.

The application adopts nanosecond laser (one time of 10 ns) to etch the metal film, and the laser spot overlapping rate is 1/2 in the etching process.

According to the application, the thickness of the metal film is about 1 micrometer, the metal film can be etched at one time by nanosecond laser, the phenomenon that laser energy is diffused to the periphery for many times due to multiple times of laser etching is avoided, and the uniformity of a copper layer exposed by the one-time laser etching method can be ensured, so that the circuit pattern with good uniformity and precision can be formed.

In the application, the metal film is positioned above the copper layer, and the processing depth can be monitored in real time in the laser etching process in a mode of laser reflection time difference. The thickness of the metal film is about 1 micrometer, and the etching depth is required to be ensured to be more than or equal to the thickness of the metal film in the laser etching process. For example, when the thickness of the metal film is 1 micron, the laser etching depth is monitored to be 2 microns (or any other value less than or equal to the thickness of the metal film and the copper layer) by means of laser reflection time difference, and the laser spot moves towards the next position. Thus, the over-etching phenomenon exists in the laser etching process.

The exposed copper layer needs to be etched later, so that the over-etching does not affect the subsequent etching of the copper layer, and the etching speed of the laser is far higher than that of the etching solution, so that the etching of the copper layer can be accelerated. Meanwhile, the over etching can ensure that the metal film is completely removed, and the influence on the subsequent copper layer etching process is avoided. The laser etching speed is high, and the metal film is removed through overetching, so that the metal film above the circuit pattern can be completely removed, and the etching speed of the circuit pattern can be accelerated.

S4: and etching the copper layer outside the metal pattern to form a circuit pattern covered by the metal pattern. The exposed copper layer may be etched using an etchant for the copper layer.

The metal film has the characteristics of acid resistance and the like, has better compactness than a dry film, can avoid the penetration etching effect of etching liquid on the metal film to the greatest extent, and ensures that a good mask effect can be realized by a thinner metal film.

And a chemical etching method is adopted to ensure the uniformity in the etching process. The etching line speed is designed according to the thickness of the copper layer. When the copper layer thickness is 10um copper thickness, the etching line speed can be set to be 6m/min.

The circuit patterns can be formed on one side of the core plate, and the copper layers can also be used for forming the circuit patterns on two sides of the core plate. When the two sides of the core plate are required to form the circuit patterns, a copper layer and a metal film can be deposited on the two sides of the core plate at the same time, and the copper layers outside the circuit patterns are removed by laser respectively. And removing the copper layer except the circuit patterns by adopting a chemical etching method to form the circuit patterns positioned on the two sides of the core plate.

In order to ensure that the redundant copper layers on the two sides of the core plate are etched simultaneously, the core plate in the etching machine is placed in the direction perpendicular to a transmission line for transmitting the core plate. When the transmission line is a horizontal transmission line, the two sides of the horizontal transmission line are respectively provided with a spray head, and the core plate is vertically arranged on the horizontal transmission line. Namely, the upper surface and the lower surface of the core plate, which are required to form a circuit pattern, are vertically arranged and are opposite to the spray heads on two sides of the horizontal transmission line, and the spray heads on two sides are used for spraying etching liquid to two sides of the core plate.

Specifically, the application can arrange the spray heads positioned on the same vertical line, the spray flow of which from top to bottom is gradually increased, and the redundant etching liquid sprayed above the core plate can fall under the action of weight, so that the uniformity of etching of copper layers at all positions can be ensured.

S5: and removing the metal film.

The application adopts the film removing liquid to remove the metal film. The stripping solution is a solution capable of reacting with the metal film to form soluble salts. And the film stripping liquid can not dissolve a copper layer and can not influence the size and the precision of a circuit pattern.

As a specific example, the main component of the stripping liquid of the application is a solution containing chloride and oxidant. When the detinned water contacts with the metallic tin, the chloride ions react with the metallic tin to form soluble stannous chloride and release electrons.

As another specific embodiment, the stripping liquid comprises the following components in parts by weight: 1-9 parts of boric acid, 45-55 parts of hydrofluoric acid and 8-12 parts of nitric acid; 30-35 parts of deionized water.

At room temperature, soaking the core plate after etching to form the circuit pattern in the film removing liquid for a period of time, taking out and wiping to remove the metal film. Or directly coating the film removing liquid on the surface of the metal film for soaking for a period of time, and wiping to remove the metal film.

The application adopts the metal film to replace the dry film or wet film in the traditional process, and patterns the metal film by a laser etching method, and dust in the environment is directly broken down by laser in the process of etching the metal film by the laser, so that the defects of openings or gaps and the like are avoided.

The metal film is formed by adopting an electroplating or chemical deposition method, coating film pressing equipment in the traditional process is not needed, a dust-free room is not needed for exposure, the steps of a circuit pattern forming process are simplified, the equipment cost is reduced, and the forming speed of the circuit pattern is improved.

According to the application, the metal film can be removed by wiping the film removing liquid at room temperature, and the removing method does not generate organic waste liquid, so that the subsequent waste liquid treatment process is avoided.

It is to be understood that the above examples only represent preferred embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the invention; it should be noted that, for a person skilled in the art, the above technical features can be freely combined, and several variations and modifications can be made without departing from the scope of the invention; therefore, all changes and modifications that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. The processing method of the high-precision circuit is characterized by comprising the following steps of:

Copper deposition electroplating is carried out on the core plate;

And removing the metal film.

2. The method of claim 1, wherein the metal film has a thickness of 1 μm or less.

3. The method of claim 1, wherein depositing a metal film on the copper layer comprises: coating film forming liquid on the copper layer, and forming a metal film by a chemical deposition method; the film forming liquid comprises a gold ion complexing agent, a tin antioxidant, a copper ion complexing agent, a divalent tin-containing compound, a gold-containing compound, a copper-containing compound and an additive.

4. A method of processing high precision wire according to claim 3, wherein the additives include gold stabilizers, masking agents, brightening agents, grain refiners and pH buffers.

5. A method of manufacturing a high precision circuit according to claim 3, wherein the film formation temperature of the chemical deposition process is 60-70 ℃; in the film forming process, the core plate where the copper layer is positioned is soaked in film forming liquid, and inert gas is filled into the film forming liquid.

6. The method of claim 1, wherein the metal film has a hardness of 92HRA or more.

7. The method of claim 1, wherein the laser overetching the metal film is performed while the laser etching the metal film to form the metal pattern.

8. The method for processing high-precision lines according to claim 1, wherein the wavelength band of the laser is 230-260nm.

9. The method for processing a high-precision circuit according to claim 1, wherein the metal film is removed by using a film removing liquid; the film removing liquid comprises the following components in parts by weight: 1-9 parts of boric acid, 45-55 parts of hydrofluoric acid and 8-12 parts of nitric acid; 30-35 parts of deionized water.