A method for manufacturing an outer layer circuit of a printed wiring board

Abstract

The embodiment of the present application discloses a kind of manufacturing methods of printed wiring board outer layer circuit, comprising: the surface of the printed wiring board after pretreatment is pasted dry film;At least two times of exposure is carried out to dry film;Wherein, the exposure area of dry film includes sealing subzone and non-sealing subzone, the number of times of exposure to sealing subzone is greater than the exposure times of non-sealing subzone;At least two times of exposure after dry film is developed;Based on the pattern of the dry film after development, the outer layer circuit of printed wiring board is formed.The embodiment of the present application can effectively reduce dry film broken hole, improve dry film sealing capacity, and guarantee product quality.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board technology, and in particular to a method for manufacturing the outer layer circuitry of a printed circuit board. Background Technology

[0002] A printed circuit board (PCB) is the carrier for the electrical connections of electronic components. It is manufactured using electronic printing techniques, and outer layer pattern transfer is a process in the production process. Outer layer pattern transfer refers to applying a photosensitive film layer to a treated copper surface, and then transferring the circuit pattern to the copper surface under ultraviolet light to form a mask pattern that resists corrosion or plating.

[0003] Dry film through-holes are a defect in PCB manufacturing, mainly occurring in large round holes or irregularly shaped holes with a diameter of 6.5mm or more. They have the following adverse effects on the PCB: In negative films, through-holes cause the copper in plated through-holes (PTH holes) to be etched away, resulting in copper-free holes and rendering them unusable; in positive films, through-holes will have copper and tin plated during pattern plating, causing copper to accumulate in non-plated through-holes (NPTH holes). Both positive and negative film through-holes affect the electrical performance of the PCB. Summary of the Invention

[0004] This invention provides a method for manufacturing the outer layer circuitry of a printed circuit board, which can effectively reduce dry film pores, improve dry film sealing capability, and ensure product quality.

[0005] This invention provides a method for fabricating the outer layer circuitry of a printed circuit board, comprising: applying a dry film to the surface of a pretreated printed circuit board; exposing the dry film at least twice; wherein the exposed areas of the dry film include sealed areas and non-sealed areas, and the number of exposures of the sealed areas is greater than the number of exposures of the non-sealed areas; developing the dry film after at least two exposures; and forming the outer layer circuitry of the printed circuit board based on the pattern of the developed dry film.

[0006] Optionally, exposing the dry film at least twice includes: exposing the dry film once; wherein the first exposure only exposes the via area; and exposing the printed circuit board after the first exposure a second time; wherein the second exposure exposes both the via area and the non-via area.

[0007] Optionally, the aperture ring width of the film during a single exposure is 2 mil smaller than the aperture ring width of the film during a second exposure.

[0008] Optionally, pretreatment of the printed circuit board includes: grinding the printed circuit board and pretreatment of the outer layer.

[0009] Optionally, the exposed area is the circuit pattern area, and the unexposed area is the non-circuit pattern area. Based on the pattern of the dry film after development, the outer layer circuit of the printed circuit board is formed by: washing away the dry film in the non-circuit pattern area during development, etching away the exposed copper layer in the non-circuit pattern area; and removing the dry film on the circuit pattern area to form the outer layer circuit of the printed circuit board.

[0010] Optionally, the exposed area is a non-circuit pattern area, and the non-exposed area is a circuit pattern area. Based on the pattern of the dry film after development, the outer layer circuit of the printed circuit board is formed by: washing away the dry film of the circuit pattern area during development, and then electroplating copper and tin in sequence on the exposed circuit pattern area; removing the dry film of the non-circuit pattern area, etching away the copper layer of the exposed non-circuit pattern area; and removing the tin on the circuit pattern area to form the outer layer circuit of the printed circuit board.

[0011] Optionally, the temperature range of the film entering the board is 45-55℃, the temperature range of the film-applying roller is 100-120℃, the film-applying speed is 2.2-2.8m / min, the film-applying pressure is 0.40-0.50MPa, the settling time after film application is 0.25-48h, and the thickness of the dry film is 45μm.

[0012] Optionally, during the developing process, the concentration of the developer is in the range of 0.8-1.2%, the developing temperature is 28-32℃, the upper spray pressure is 1.0-1.4 kg / cm2, the lower spray pressure is 0.7-1.1 kg / cm2, and the developing speed is 3.4-4.0 m / min.

[0013] Optionally, the grinding plate adopts a grinding plate line, the grinding plate is ground once, the grinding plate speed range is 2.5-3.5m / min, the abrasive belt grinding plate section is closed, and the ceramic brush grinding plate section and the non-woven fabric brush grinding plate section are opened. The current control parameters of the ceramic brush grinding plate section and the non-woven fabric brush grinding plate section are in the range of 0.5-1.5A.

[0014] Optionally, the grinding speed of the outer layer pretreatment plate is in the range of 1.7-2.3 m / min, the drying temperature is in the range of 80-90℃, and the inspection index for the effect of the outer layer pretreatment is that the water crack point is greater than or equal to 45 seconds.

[0015] The method for manufacturing the outer layer circuit of a printed circuit board provided in this invention involves subjecting the dry film to at least two consecutive exposures. The exposed areas of the dry film include a sealing area and a non-sealing area, and the number of exposures to the sealing area is greater than the number of exposures to the non-sealing area. In other words, by subjecting the sealing area to at least two consecutive exposures, the sealing capability of the dry film in the sealing area can be improved, effectively reducing dry film breakage and ensuring product quality.

[0016] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a method for manufacturing the outer layer circuit of a printed circuit board according to an embodiment of the present invention;

[0019] Figure 2 This is a flowchart of another method for manufacturing the outer layer circuit of a printed circuit board according to an embodiment of the present invention;

[0020] Figure 3 This is a flowchart of another method for manufacturing the outer layer circuit of a printed circuit board according to an embodiment of the present invention;

[0021] Figure 4 This is a flowchart of another method for manufacturing the outer layer circuit of a printed circuit board according to an embodiment of the present invention;

[0022] Figure 5 This is a flowchart of another method for manufacturing the outer layer circuit of a printed circuit board according to an embodiment of the present invention;

[0023] Figure 6 This is a flowchart of another method for manufacturing the outer layer circuit of a printed circuit board provided in an embodiment of the present invention. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0025] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0026] Figure 1 This is a flowchart illustrating a method for fabricating the outer layer circuitry of a printed circuit board according to an embodiment of the present invention, as shown below. Figure 1 As shown, the method for fabricating the outer layer circuitry of this printed circuit board includes the following steps:

[0027] S101. Apply dry film to the surface of the pretreated printed circuit board.

[0028] Pre-processing includes grinding the printed circuit board and pre-treatment of the outer layer.

[0029] The purpose of PCB grinding is to remove burrs, plating copper particles, and other imperfections from the PCB surface, such as those around the vias. This prevents these defects from affecting the dry film thickness after applying the sealant to the vias, impacting sealing performance, or even puncturing the dry film. Grinding is performed using a grinding line. This line has different types of brushes, each with specific applications. For example, ceramic brushes and abrasive belts, due to their hard abrasive particles, are particularly effective at removing hard via-clogging resin. Nylon needle brushes, with their relatively weak cutting force, are generally used before applying solder mask and before applying the outer dry film. Nylon needle brushes can generally only remove minor burrs; if the burrs are coarse, multiple grinding sessions are required, reducing the brush's lifespan. In contrast, non-woven fabric brushes have a wider range of applications. They can be used for post-treatment repair after removing via-clogging resin, and also for strong deoxidation cleaning and roughening of the copper surface before applying solder mask. However, the cutting force of non-woven fabric brushes is less than that of ceramic brushes. In this embodiment, the grinding process is performed once, with a grinding speed ranging from 2.5 to 3.5 m / min. The belt grinding section is closed, while the ceramic brush grinding section and the non-woven fabric brush grinding section are open. The current control parameters for the ceramic brush grinding section and the non-woven fabric brush grinding section range from 0.5 to 1.5 A. If the dwell time during the grinding process is too long, the PCB board surface will come into contact with oxygen in the air and undergo an oxidation reaction. Therefore, the grinding process should be completed in a short time.

[0030] The purpose of the outer layer pretreatment is to remove contaminants from the copper surface and increase the surface roughness to facilitate the lamination process (i.e., the dry film lamination process). Optionally, in this embodiment, the grinding speed of the outer layer pretreatment ranges from 1.7 to 2.3 m / min, the drying temperature ranges from 80 to 90°C, and the inspection index for the outer layer pretreatment effect is that the water crack point is greater than or equal to 45 seconds.

[0031] Dry film lamination involves bonding a dry film onto a cleaned and roughened copper-clad laminate under heated and pressurized conditions. During lamination, the preheating temperature, lamination speed, time, and ventilation are strictly controlled. Excessive temperature or time can lead to development difficulties, reduced resolution, and difficulty in film removal. In this embodiment, the board entry temperature range is set to 45-55℃, the lamination roller temperature range to 100-120℃, the lamination speed range to 2.2-2.8 m / min, the lamination pressure range to 0.40-0.50 MPa, the post-lamination resting time range to 0.25-48 h, and the dry film thickness to 45 μm.

[0032] S102. Expose the dry film at least twice.

[0033] The exposure area of ​​the dry film includes a sealed area and a non-sealed area, and the sealed area is exposed more times than the non-sealed area.

[0034] Optionally, the dry film is exposed once; wherein the first exposure only exposes the via area; the printed circuit board after the first exposure is then exposed a second time; wherein the second exposure exposes both the via area and the non-via area.

[0035] Optionally, the dry film is exposed once; wherein the first exposure only exposes the sealing area; the printed circuit board after the first exposure is exposed a second time; wherein the second exposure also only exposes the sealing area; the printed circuit board after the second exposure is exposed a third time; wherein the third exposure exposes both the sealing area and the non-sealing area.

[0036] Specifically, if the film is a negative plate, the exposed area is the circuit pattern area, and the unexposed area is the non-circuit pattern area; if the film is a positive plate, the exposed area is the non-circuit pattern area, and the exposed area is the circuit pattern area. First, align the film with the circuit board with the pressed dry film, then place it on an exposure machine for exposure. The portion of the dry film on the circuit board exposed to light hardens and is not affected by the developer. For example, an LDI exposure machine is used; if the film is a negative plate, the exposure energy is 5-7 stops; if the film is a positive plate, the exposure energy is 6-8 stops.

[0037] In the light-transmitting areas of the film, under ultraviolet irradiation, the photoinitiator absorbs light energy and decomposes into free radicals. These free radicals then initiate polymerization and cross-linking reactions of the monomers, forming large molecular structures insoluble in dilute solutions. The sealing area undergoes at least two exposures with higher energy than other areas, enhancing the dry film cross-linking reaction and improving sealing ability.

[0038] S103. Develop the dry film after at least two exposures.

[0039] The development mechanism involves the reaction of the active groups in the unexposed portions of the dry film with the developer to form soluble substances, which then dissolve, thus removing the unexposed areas while preventing swelling of the exposed portions. If the film is a positive film, an alkaline etching solution is used; if it is a negative film, an acidic etching solution is used. To ensure development quality, the developer concentration, temperature, and development time must be controlled within appropriate operating ranges. Excessive temperature or development time will reduce the quality, hardness, and chemical resistance of the dry film. In this embodiment, the developer concentration is set to 0.8-1.2%, the development temperature to 28-32℃, the upper spray pressure to 1.0-1.4 kg / cm², the lower spray pressure to 0.7-1.1 kg / cm², and the development speed to 3.4-4.0 m / min. The developer concentration range is 0.8-1.2%, the developing temperature is 28-32℃, the upper spray pressure is 1.0-1.4 kg / cm2, the lower spray pressure is 0.7-1.1 kg / cm2, and the developing speed is 3.4-4.0 m / min.

[0040] S104. Based on the pattern of the developed dry film, form the outer layer circuit of the printed circuit board.

[0041] If the film is a negative, during development, the dry film in the non-circuit pattern areas is washed away, and the exposed copper layer in the non-circuit pattern areas is etched away. The dry film on the circuit pattern areas is then removed, forming the outer layer of the printed circuit board. Since the exposure area of ​​the dry film includes both the sealing and non-sealing areas, meaning that the circuit pattern area includes the sealing area, and the dry film in the sealing area covers the PTH vias, the sealing area has undergone at least two exposures with stronger exposure energy compared to other areas. This results in a more intense cross-linking reaction of the dry film, improving the sealing capability. When the exposed copper layer in the non-circuit pattern areas is etched away, the sealing on the PTH vias remains intact, and the copper in the PTH vias is not etched away, thus not affecting the electrical performance of the PCB board.

[0042] If the film is a positive film, the exposed area is the non-circuit pattern area, and the non-exposed area is the circuit pattern area. During development, the dry film in the circuit pattern area is washed away, and copper and tin are electroplated sequentially in the exposed circuit pattern area. The dry film in the non-circuit pattern area is then removed, and the copper layer in the exposed non-circuit pattern area is etched away. The tin on the circuit pattern area is removed, forming the outer layer circuit of the printed circuit board. Since the exposed area of ​​the dry film includes the sealing area and the non-sealing area, that is, at this time the non-circuit pattern area includes the sealing area. The dry film in the sealing area covers the NPTH holes. The sealing area has been exposed at least twice, and the exposure energy is stronger than other areas. The cross-linking reaction of the dry film is intense, and the sealing ability is improved. When copper and tin are electroplated sequentially in the exposed circuit pattern area, the sealing on the NPTH hole is not broken. Copper and tin will not be plated in the NPTH hole. During etching, the copper in the NPTH hole will be etched cleanly, and there will be no copper residue, thus not affecting the electrical performance of the PCB board.

[0043] The method for manufacturing the outer layer circuit of a printed circuit board provided in this invention involves subjecting the dry film to at least two consecutive exposures. The exposed areas of the dry film include a sealing area and a non-sealing area, and the number of exposures to the sealing area is greater than the number of exposures to the non-sealing area. In other words, by subjecting the sealing area to at least two consecutive exposures, the sealing capability of the dry film in the sealing area can be improved, effectively reducing dry film breakage and ensuring product quality.

[0044] Figure 2 This is a flowchart of another method for fabricating the outer layer circuitry of a printed circuit board according to an embodiment of the present invention, as shown below. Figure 2 As shown, the method for fabricating the outer layer circuitry of this printed circuit board includes the following steps:

[0045] S201. Apply dry film to the surface of the pretreated printed circuit board.

[0046] S202. Expose the dry film once.

[0047] One of the exposures only covers the area where Confucius was sealed off.

[0048] S203. The printed circuit board that has undergone one exposure will be exposed a second time.

[0049] In this process, both the sealed and unsealed via areas are exposed during the second exposure. The via ring width on the film during the first exposure is 2 mil smaller than that during the second exposure. This prevents misalignment between the first and second exposures, thus avoiding distortion of the circuit pattern.

[0050] S204. Develop the dry film after at least two exposures.

[0051] S205. Based on the pattern of the developed dry film, form the outer layer circuit of the printed circuit board.

[0052] Figure 3 This is a flowchart of another method for fabricating the outer layer circuitry of a printed circuit board according to an embodiment of the present invention, as shown below. Figure 3 As shown, the method for fabricating the outer layer circuitry of this printed circuit board includes the following steps:

[0053] S301. Apply dry film to the surface of the pretreated printed circuit board.

[0054] S302. Expose the dry film at least twice.

[0055] S303. Develop the dry film after at least two exposures.

[0056] S304. During development, the dry film in the non-circuit pattern area is washed away, and the exposed copper layer in the non-circuit pattern area is etched away.

[0057] S305. Remove the dry film from the circuit pattern area to form the outer layer of the printed circuit board.

[0058] Specifically, in this embodiment, the film is a negative film, the exposed area is the circuit pattern area, and the non-exposed area is the non-circuit pattern area. Since the exposed area of ​​the dry film includes the via sealing area and the non-via sealing area, that is, the circuit pattern area includes the via sealing area. The dry film in the via sealing area covers the PTH vias. The via sealing area has undergone at least two exposures, and the exposure energy is stronger than other areas. The cross-linking reaction of the dry film is intense, and the sealing ability is improved. When the copper layer of the exposed non-circuit pattern area is etched away, the vias on the PTH vias are not broken, and the copper in the PTH vias will not be etched away, thus not affecting the electrical performance of the PCB board.

[0059] Figure 4 This is a flowchart of another method for fabricating the outer layer circuitry of a printed circuit board according to an embodiment of the present invention, as shown below. Figure 4 As shown, the method for fabricating the outer layer circuitry of this printed circuit board includes the following steps:

[0060] S401. Apply dry film to the surface of the pretreated printed circuit board.

[0061] S402. Expose the dry film at least twice.

[0062] S403. Develop the dry film after at least two exposures.

[0063] S404. During development, the dry film in the circuit pattern area is washed off, and copper and tin are electroplated in sequence in the exposed circuit pattern area.

[0064] S405: Remove the dry film from the non-circuit pattern area and etch away the exposed copper layer in the non-circuit pattern area.

[0065] S406. Remove the solder from the circuit pattern area to form the outer layer of the printed circuit board.

[0066] Specifically, in this embodiment, the film substrate is a positive film, and the exposure area is the non-circuit pattern area, while the exposure area is the circuit pattern area. Since the exposure area of ​​the dry film includes the via sealing area and the non-via sealing area, that is, the non-circuit pattern area includes the via sealing area. The dry film in the via sealing area covers the NPTH vias. The via sealing area has undergone at least two exposures, and the exposure energy is stronger than other areas. The cross-linking reaction of the dry film is intense, and the sealing ability is improved. When copper and tin are electroplated sequentially in the exposed circuit pattern area, the vias on the NPTH vias are not broken, and copper and tin will not be plated in the NPTH vias. During etching, the copper in the NPTH vias will be etched cleanly, leaving no copper residue, thus not affecting the electrical performance of the PCB board.

[0067] Figure 5 This is a flowchart of another method for fabricating the outer layer circuitry of a printed circuit board according to an embodiment of the present invention, as shown below. Figure 5 As shown, the method for fabricating the outer layer circuitry of this printed circuit board includes the following steps:

[0068] S501. Apply dry film to the surface of the pretreated printed circuit board.

[0069] S502, Expose the dry film once.

[0070] S503, The printed circuit board that has undergone one exposure will be exposed a second time.

[0071] S504. Develop the dry film after at least two exposures.

[0072] S505. During development, the dry film in the non-circuit pattern area is washed away, and the exposed copper layer in the non-circuit pattern area is etched away.

[0073] S506. Remove the dry film from the circuit pattern area to form the outer layer of the printed circuit board.

[0074] Figure 6 This is a flowchart of another method for fabricating the outer layer circuitry of a printed circuit board according to an embodiment of the present invention, as shown below. Figure 6 As shown, the method for fabricating the outer layer circuitry of this printed circuit board includes the following steps:

[0075] S601. Apply dry film to the surface of the pretreated printed circuit board.

[0076] S602. Expose the dry film once.

[0077] S603. The printed circuit board that has undergone one exposure will be exposed a second time.

[0078] S604. Develop the dry film after at least two exposures.

[0079] S605. During development, the dry film in the circuit pattern area is washed off, and copper and tin are electroplated in sequence in the exposed circuit pattern area.

[0080] S606. Remove the dry film from the non-circuit pattern area and etch away the exposed copper layer of the non-circuit pattern area.

[0081] S607. Remove the solder from the circuit pattern area to form the outer layer of the printed circuit board.

[0082] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0083] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for manufacturing the outer layer circuitry of a printed circuit board, characterized in that, include: Apply dry film to the surface of the pretreated printed circuit board; The dry film is exposed at least twice; wherein the exposed area of ​​the dry film includes a sealed area and a non-sealed area, and the number of exposures of the sealed area is greater than the number of exposures of the non-sealed area; Develop the dry film after at least two exposures; Based on the pattern of the developed dry film, the outer layer circuitry of the printed circuit board is formed. The process of exposing the dry film at least twice includes: The dry film is exposed once; wherein, the single exposure only exposes the sealing area; The printed circuit board that has undergone one exposure is then subjected to a second exposure; wherein the second exposure exposes both the sealed area and the unsealed area.

2. The method for manufacturing the outer layer circuitry of a printed circuit board according to claim 1, characterized in that, The aperture ring width of the film during the first exposure is 2 mil smaller than the aperture ring width of the film during the second exposure.

3. The method for manufacturing the outer layer circuitry of a printed circuit board according to claim 1, characterized in that, The preprocessing of the printed circuit board includes: The printed circuit board is subjected to grinding and outer layer pretreatment.

4. The method for manufacturing the outer layer circuitry of a printed circuit board according to claim 1, characterized in that, The exposed area is a circuit pattern area, and the unexposed area is a non-circuit pattern area. The outer layer circuit of the printed circuit board is formed based on the pattern of the developed dry film, including: During development, the dry film of the non-circuit pattern area is washed away, and the exposed copper layer of the non-circuit pattern area is etched away. The dry film on the circuit pattern area is removed to form the outer layer circuit of the printed circuit board.

5. The method for manufacturing the outer layer circuitry of a printed circuit board according to claim 1, characterized in that, The exposed area is a non-circuit pattern area, and the non-exposed area is a circuit pattern area. The pattern formed based on the developed dry film to create the outer layer circuit of the printed circuit board includes: During development, the dry film of the circuit pattern area is washed away, and copper and tin are electroplated sequentially on the exposed circuit pattern area. Remove the dry film from the non-circuit pattern area and etch away the exposed copper layer of the non-circuit pattern area; Remove the solder from the circuit pattern area to form the outer layer circuit of the printed circuit board.

6. The method for manufacturing the outer layer circuitry of a printed circuit board according to claim 1, characterized in that, The temperature range of the film entering the board is 45-55℃, the temperature range of the film-applying roller is 100-120℃, the film-applying speed is 2.2-2.8m / min, the film-applying pressure is 0.40-0.50MPa, the settling time after film application is 0.25-48h, and the thickness of the dry film is 45μm.

7. The method for manufacturing the outer layer circuitry of a printed circuit board according to claim 1, characterized in that, During the developing process, the concentration of the developing solution ranges from 0.8% to 1.2%, the developing temperature is 28-32℃, the upper spray pressure is 1.0-1.4 kg / cm², the lower spray pressure is 0.7-1.1 kg / cm², and the developing speed is 3.4-4.0 m / min.

8. The method for manufacturing the outer layer circuitry of a printed circuit board according to claim 3, characterized in that, The grinding plate adopts a grinding plate line, the grinding plate is ground once, the grinding plate speed range is 2.5-3.5m / min, the abrasive belt grinding plate section is closed, and the ceramic brush grinding plate section and the non-woven fabric brush grinding plate section are opened. The current control parameter range of the ceramic brush grinding plate section and the non-woven fabric brush grinding plate section is 0.5-1.5A.

9. The method for manufacturing the outer layer circuitry of a printed circuit board according to claim 3, characterized in that, The grinding speed range for the outer layer pretreatment is 1.7-2.3 m / min, the drying temperature range is 80-90℃, and the inspection index for the outer layer pretreatment effect is that the water crack point is greater than or equal to 45 seconds.

Images