Processing method for manufacturing precise circuit

Abstract

The invention discloses a processing method for manufacturing a precise circuit. The processing method comprises the following steps of: drilling a copper-clad substrate by using a drilling machine; generating a circuit pattern on the surface of the copper foil coated with the photosensitive dry film by using a laser beam according to a design file; putting the copper-clad substrate subjected to laser exposure treatment into a developing solution, and removing the photosensitive dry film in an unexposed area to expose the surface of the copper foil; after the exposed copper foil is pretreated, a first copper plating layer is deposited on the surface of the copper foil through chemical copper plating; the first copper plating layer is covered with the photoresist dry film again for secondary exposure, the part needing to be metalized is reserved, and electroplating thickening is carried out to obtain a second copper plating layer; and removing the photoresist dry film by using strong base, and removing the redundant copper layer by using flash etching liquid to obtain the circuit board. According to the invention, the required circuit copper is plated, then the redundant bottom copper is etched, and the local secondary copper plating is carried out, so that a plurality of procedures in the traditional process are reduced, the production period is shortened, the yield is improved, the usage amount of chemical agents is reduced, and the risk of environmental pollution is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of PCB processing, and in particular to a processing method for manufacturing precision circuits. Background Art

[0002] The description in this section merely provides background information related to the present disclosure and may not constitute prior art.

[0003] The miniaturization and advancement of high-performance electronic devices are driving higher demands on the width and spacing of printed circuit boards (PCBs). Traditional subtractive etching methods struggle to achieve such fine lines due to lateral diffusion during etching. While existing advanced processes such as laser direct imaging (LDI) and semi-additive etching (mSAP) have improved resolution to some extent, they still cannot fully meet the demand for line widths of 15 microns and smaller. Therefore, a new manufacturing method is needed to overcome the limitations of existing technologies.

[0004] It should be noted that the above technical background is merely provided to provide a clear and complete description of the technical solutions of the present invention and to facilitate understanding by those skilled in the art. Simply because these solutions are described in the technical background section of the present invention, it should not be assumed that the above technical solutions are well known to those skilled in the art. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a processing method for manufacturing precision circuits in view of the deficiencies of the existing technology.

[0006] The present application discloses a method for manufacturing a precision circuit, comprising the following steps:

[0007] Providing a copper clad substrate;

[0008] Drilling holes in the copper-clad substrate using a drilling machine;

[0009] Coating a photosensitive dry film on the copper foil surface of the copper clad substrate;

[0010] Using a laser beam to generate a circuit pattern according to the design file on the surface of the copper foil coated with a photosensitive dry film;

[0011] placing the copper-clad substrate after laser exposure treatment into a developer to remove the photosensitive dry film in the unexposed area to expose the copper foil surface;

[0012] After pre-treating the exposed copper foil, depositing a first copper plating layer on the surface of the copper foil by chemical copper plating;

[0013] The first copper plating layer is covered with a photoresist dry film again for secondary exposure, and the portion to be metallized is retained, and electroplating is performed to thicken the portion to obtain a second copper plating layer;

[0014] Use strong alkali to remove the photoresist dry film, and use flash etching solution to remove the excess copper layer to obtain a circuit board with a predetermined circuit pattern;

[0015] Clean and inspect the circuit boards.

[0016] Furthermore, in the above-mentioned processing method for making precision circuits, in the step of "using a laser beam to generate a circuit pattern according to the design file on the surface of the copper foil coated with a photosensitive dry film", the laser beam has a wavelength of 355 nanometers, a power of 20 watts, a scanning speed of 1 meter / second, and an exposure time of 10 milliseconds.

[0017] Furthermore, in the above-mentioned processing method for making precision circuits, in the step of "pre-treating the exposed copper foil, and then depositing a first copper plating layer on the surface of the copper foil by chemical copper plating", the chemical copper plating conditions are 30°C, a pH value of 9.5, and a reaction time of 15 minutes.

[0018] Furthermore, in the above-mentioned processing method for making precision circuits, in the step of "pre-treating the exposed copper foil and then depositing a first copper plating layer on the surface of the copper foil by chemical copper plating", the thickness of the first copper plating layer is 1 micron.

[0019] Furthermore, in the above-mentioned processing method for making precision circuits, in the step of "covering the first copper-plated layer with photoresist again for secondary exposure, retaining the part that needs to be metallized, and electroplating thickening to obtain a second copper-plated layer", the electroplating thickening conditions are a current density of 2 amperes / square decimeter, a temperature of 35°C, and a time of 60 minutes.

[0020] Furthermore, in the above-mentioned processing method for making precision circuits, in the step of "covering the first copper-plated layer with a photoresist dry film again for secondary exposure, retaining the portion to be metallized, and performing electroplating to thicken it to obtain a second copper-plated layer", the electroplating tank solution includes a copper sulfate concentration of 230g / L to 270g / L, a sulfuric acid concentration of 40g / L to 60g / L, and a chloride ion concentration of 40ppm to 80ppm.

[0021] Furthermore, in the above-mentioned processing method for making precision circuits, in the step of "covering the first copper-plated layer with a photoresist dry film again for secondary exposure, retaining the part that needs to be metallized, and electroplating to thicken it to obtain a second copper-plated layer", pickling, lamination, exposure and development treatment are performed before electroplating the second copper-plated layer, and the concentration of sulfuric acid in the pickling is 2-4%.

[0022] Furthermore, in the above-mentioned processing method for making precision circuits, in the step of "using a strong alkali to remove the photoresist dry film, and using a flash etching solution to remove the excess copper layer to obtain a circuit board with a predetermined circuit pattern", the sulfuric acid concentration in the flash etching solution is 70±30g / L and the hydrogen peroxide concentration is 10±3g / L.

[0023] Furthermore, in the above-mentioned processing method for making precision circuits, in the step of "cleaning and inspecting the circuit board", plasma cleaning is used to remove residues on the circuit board. The plasma cleaning parameters are an oxygen flow rate of 20 standard cubic centimeters per minute, a radio frequency power of 300 watts, and a processing time of 5 minutes.

[0024] In summary, the above structure adopted in the embodiment of the present invention has the following advantages:

[0025] The processing method for making precision circuits described in the present invention can stably manufacture precision circuits with a line width of 15 microns or less. The required circuit copper is directly plated, and then the excess base copper is etched away. According to customer requirements, for the processing of local large copper surfaces, if the copper thickness obtained by the first copper plating does not meet the customer specifications, a second copper plating is performed. The local secondary copper plating reduces multiple steps in the traditional process, shortens the production cycle, improves the yield, reduces the use of chemical agents, and reduces the risk of environmental pollution.

[0026] To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only for reference and illustration and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0028] Figure 1 1 is a flow chart of a processing method for producing a precision circuit in an embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of two copper-plated layers in an embodiment of the present invention;

[0030] Figure 3 Schematic diagram of line width after electroplating in an embodiment of the present invention;

[0031] Figure 4 Schematic diagram of line width after flash etching in an embodiment of the present invention;

[0032] Reference numerals in the above drawings: 1, copper-clad substrate; 2, first copper-plated layer; 3, second copper-plated layer. DETAILED DESCRIPTION

[0033] To help those skilled in the art better understand the technical solutions in this specification, the following will provide a clear and complete description of the technical solutions in the embodiments of this specification, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of this specification, not all of them. All other embodiments derived by those skilled in the art based on the embodiments in this specification without creative effort shall fall within the scope of protection of this specification.

[0034] The following is an explanation of the embodiments of the present invention through specific embodiments. Those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are only simple schematic illustrations and are not depicted according to actual dimensions. It is stated in advance. The following embodiments will further explain the relevant technical contents of the present invention in detail, but the disclosed contents are not intended to limit the scope of protection of the present invention.

[0035] It should be understood that although terms such as "first," "second," and "third" may be used herein to describe various components or signals, these components or signals should not be limited by these terms. These terms are primarily used to distinguish one component from another, or one signal from another. In addition, the term "or" as used herein may include any one or more combinations of the associated listed items, as appropriate.

[0036] Reference Figures 1 to 4 As shown, the embodiment of the present application discloses a processing method for manufacturing a precision circuit, comprising the following steps:

[0037] Providing a copper clad substrate;

[0038] Drilling holes in the copper-clad substrate using a drilling machine;

[0039] Coating a photosensitive dry film on the copper foil surface of the copper clad substrate;

[0040] Using a laser beam to generate a circuit pattern according to the design file on the surface of the copper foil coated with a photosensitive dry film;

[0041] placing the copper-clad substrate after laser exposure treatment into a developer to remove the photosensitive dry film in the unexposed area to expose the copper foil surface;

[0042] After pre-treating the exposed copper foil, depositing a first copper plating layer on the surface of the copper foil by chemical copper plating;

[0043] The first copper plating layer is covered with a photoresist dry film again for secondary exposure, and the portion to be metallized is retained, and electroplating is performed to thicken the portion to obtain a second copper plating layer;

[0044] Use strong alkali to remove the photoresist dry film, and use flash etching solution to remove the excess copper layer to obtain a circuit board with a predetermined circuit pattern;

[0045] Clean and inspect the circuit boards.

[0046] Specifically, in this embodiment, in the step "generating a circuit pattern according to the design file on the surface of the copper foil coated with the photosensitive dry film using a laser beam," the laser beam has a wavelength of 355 nanometers, a power of 20 watts, a scanning speed of 1 meter per second, and an exposure time of 10 milliseconds. The laser power, scanning speed, and exposure time are optimized to ensure clear and accurate pattern formation.

[0047] Specifically, in this embodiment, in the step of "pre-treating the exposed copper foil and then depositing a first copper plating layer on the surface of the copper foil by chemical copper plating", the chemical copper plating conditions are 30°C, pH 9.5, and reaction time is 15 minutes.

[0048] Specifically, in this embodiment, in the step of "pre-treating the exposed copper foil and then depositing a first copper plating layer on the surface of the copper foil by electroless copper plating," the thickness of the first copper plating layer is 1 micron. This step enhances the uniformity of current distribution during the subsequent electroplating process.

[0049] Specifically, in this embodiment, in the step "covering the first copper-plated layer with photoresist and performing a second exposure, retaining the portion to be metallized, and performing electroplating to thicken the second copper-plated layer," the electroplating thickening conditions are a current density of 2 amperes per square decimeter, a temperature of 35°C, and a duration of 60 minutes. All electroplating requirements are completed in a single stage to ensure consistent electroplating parameters. If a line width limit is encountered, a second electroplating cycle can be used to overcome the problem.

[0050] Specifically, in this embodiment, in the step of "re-covering the first copper-plated layer with a photoresist dry film and performing a second exposure, retaining the portion to be metallized, and performing electroplating to thicken the portion to obtain a second copper-plated layer," the electroplating bath solution includes a copper sulfate concentration of 230 g / L to 270 g / L, a sulfuric acid concentration of 40 g / L to 60 g / L, and a chloride ion concentration of 40 ppm to 80 ppm. The thickness of the first and second copper-plated layers is the desired final copper thickness.

[0051] Specifically, in this embodiment, in the step of "covering the first copper-plated layer with a photoresist dry film again and exposing it a second time, retaining the portion that needs to be metallized, and performing electroplating to thicken it to obtain a second copper-plated layer", pickling, lamination, exposure and development treatments are performed before electroplating the second copper-plated layer, and the concentration of sulfuric acid in the pickling is 2-4%.

[0052] Specifically, in this embodiment, in the step "using a strong base to remove the photoresist dry film and using a flash etching solution to remove the excess copper layer to obtain a circuit board with a predetermined circuit pattern," the flash etching solution contains a sulfuric acid concentration of 70±30 g / L and a hydrogen peroxide concentration of 10±3 g / L. All unnecessary dry films are removed at once, and the baking temperature and time are then adjusted according to actual needs to ensure that material properties are not affected.

[0053] Specifically, in this embodiment, in the step of "cleaning and inspecting the circuit board", plasma cleaning is used to remove residues on the circuit board. The plasma cleaning parameters are an oxygen flow rate of 20 standard cubic centimeters per minute, a radio frequency power of 300 watts, and a processing time of 5 minutes.

[0054] After cleaning the circuit boards, they can be fully inspected for quality using automated optical inspection or online testing to ensure they meet standards.

[0055] By using the above method, a special resin material with low dielectric constant and low loss tangent is used as the substrate, and an ultra-thin, high-purity electrolytic copper foil is selected as the conductive layer material to provide an FR4 copper-clad laminate with a thickness of 0.8 mm and a copper foil thickness of 18 microns. The photosensitive dry film is a UV-curable dry film with high sensitivity and a thickness of 10 microns. In the traditional process, the entire copper-clad laminate is first copper-plated and then the unnecessary copper layer is etched away. After the process flow of copper plating + copper reduction + circuit (pre-treatment + lamination + exposure + development + etching + film removal), the processing method provided in this embodiment Combining the advantages of laser direct imaging technology and semi-additive method, the required circuit copper is directly plated, and then the excess base copper is etched away. According to customer requirements, for the processing of local large copper surfaces, the copper thickness obtained by one copper plating does not meet the customer specifications. In this embodiment, a secondary copper plating is performed. The local secondary copper plating reduces the multiple steps in the traditional process, shortens the production cycle, improves the yield, reduces the use of chemicals, and reduces the risk of environmental pollution. It is suitable for the manufacture of various types of HDI (high-density interconnect) circuit boards, especially for application scenarios of high-frequency and high-speed signal transmission.

[0056] The contents disclosed above are only preferred feasible embodiments of the present invention and do not limit the scope of the patent application of the present invention. Therefore, all equivalent technical changes made using the contents of the description and drawings of the present invention are included in the scope of the patent application of the present invention.

[0057] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0058] Although the present application has been described through embodiments, those skilled in the art will appreciate that there are many modifications and variations to the present application without departing from the spirit of the present application. It is intended that the appended embodiments include these modifications and variations without departing from the present application.

Claims

1. A processing method for making a precision circuit, characterized in that: The following steps are involved: Providing a copper clad substrate; Drilling holes in the copper-clad substrate using a drilling machine; Coating a photosensitive dry film on the copper foil surface of the copper clad substrate; Using a laser beam to generate a circuit pattern according to the design file on the surface of the copper foil coated with a photosensitive dry film; placing the copper-clad substrate after laser exposure treatment into a developer to remove the photosensitive dry film in the unexposed area to expose the copper foil surface; After pre-treating the exposed copper foil, depositing a first copper plating layer on the surface of the copper foil by chemical copper plating; The first copper plating layer is covered with a photoresist dry film again for secondary exposure, and the portion to be metallized is retained, and electroplating is performed to thicken the portion to obtain a second copper plating layer; Use strong alkali to remove the photoresist dry film, and use flash etching solution to remove the excess copper layer to obtain a circuit board with a predetermined circuit pattern; Clean and inspect the circuit boards.

2. The method for producing a precision circuit according to claim 1, wherein: In the step of "generating a circuit pattern according to the design file on the surface of the copper foil coated with the photosensitive dry film using a laser beam", the laser beam has a wavelength of 355 nanometers, a power of 20 watts, a scanning speed of 1 meter per second, and an exposure time of 10 milliseconds.

3. The processing method for producing a precision circuit according to claim 1, characterized in that: In the step of "pre-treating the exposed copper foil and depositing a first copper plating layer on the surface of the copper foil by chemical copper plating", the chemical copper plating conditions are 30° C., a pH value of 9.5, and a reaction time of 15 minutes.

4. The processing method for producing a precision circuit according to claim 1, characterized in that: In the step of "pre-treating the exposed copper foil and depositing a first copper plating layer on the surface of the copper foil by chemical copper plating", the thickness of the first copper plating layer is 1 micron.

5. The processing method for producing a precision circuit according to claim 1, characterized in that: In the step of "covering the first copper-plated layer with photoresist again and performing secondary exposure, retaining the portion to be metallized, and performing electroplating to thicken the portion to obtain a second copper-plated layer", the electroplating thickening conditions are a current density of 2 amperes per square decimeter, a temperature of 35°C, and a time of 60 minutes.

6. The processing method for manufacturing a precision circuit according to claim 1, characterized in that: In the step of "covering the first copper-plated layer with a photoresist dry film again for secondary exposure, retaining the portion to be metallized, and performing electroplating to thicken the portion to obtain a second copper-plated layer", the electroplating bath solution includes a copper sulfate concentration of 230 g / L to 270 g / L, a sulfuric acid concentration of 40 g / L to 60 g / L, and a chloride ion concentration of 40 ppm to 80 ppm.

7. The method for manufacturing a precision circuit according to claim 1, characterized in that: In the step of "covering the first copper-plated layer with a photoresist dry film again and performing secondary exposure, retaining the portion to be metallized, and performing electroplating to thicken the portion to obtain a second copper-plated layer", pickling, lamination, exposure, and development are performed before electroplating the second copper-plated layer. The concentration of sulfuric acid in the pickling is 2-4%.

8. The method for manufacturing a precision circuit according to claim 1, characterized in that: In the step of "using a strong base to remove the photoresist dry film and using a flash etching solution to remove the excess copper layer to obtain a circuit board with a predetermined circuit pattern", the sulfuric acid concentration in the flash etching solution is 70±30g / L and the hydrogen peroxide concentration is 10±3g / L.

9. The method for manufacturing a precision circuit according to claim 1, characterized in that: In the step of "cleaning and inspecting the circuit board", plasma cleaning is used to remove residues on the circuit board. The plasma cleaning parameters are an oxygen flow rate of 20 standard cubic centimeters per minute, a radio frequency power of 300 watts, and a treatment time of 5 minutes.

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