Circuit board integrated surface treatment process

Abstract

The application discloses a kind of line board comprehensive surface treatment processes, comprising the following steps: front process, the first pad area on the edge of line board is covered with solder resist ink, then the area not needing gold plating is covered with dry film in the middle second pad position of line board, and the space of second pad is left in second pad position;First time paste tape, first tape is pasted around the solder resist window of reserved first pad;First layer metal processing, nickel gold is deposited on the first pad, and gold is plated on the second pad;Second time paste tape, second tape is pasted around the solder resist window of the first pad and the solder resist window of the second pad;Second layer metal processing, gold is plated on the first pad, and after the first pad is plated with gold, the lead is removed with a knife, and nickel gold is deposited on the second pad;Tin spraying, line board is passed through tin spraying device;Leveling, tin paste is leveled using hot air;Post-processing, the line board after tin spraying is dried.

Description

Technical Field

[0001] This invention relates to the field of circuit board technology, and in particular to a comprehensive surface treatment process for circuit boards. Background Technology

[0002] As the PCB industry gradually shifts from conventional single or two types of surface treatment designs to designs with three or more types of surface treatments, there are currently no reliable process flow methods in the industry that can be implemented. In particular, when there are multiple surface treatments in the same PCB design, the industry's general practice is to recommend that the PCB design end adjust to two types, which cannot meet the design end requirements. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a surface treatment process for the second pad of a circuit board, which can integrate different surface treatment processes into the same circuit board design, thus meeting the requirements of the design end.

[0004] A circuit board surface treatment process according to a first aspect of the present invention includes the following steps:

[0005] In the pre-process, after etching the circuit on the circuit board, solder resist ink is covered in the area of ​​the first pad on the edge of the circuit board, and a solder resist opening is left for the first pad. Then, dry film is covered in the area of ​​the second pad in the middle of the circuit board where no gold plating is required, and an empty space is left for the second pad.

[0006] The first time the tape is applied, the first tape is applied around the solder mask opening of the reserved first pad. After the first tape is applied, the area of ​​the first pad that needs to be immersed in nickel gold is exposed. When applying the first tape, the first tape is cut out with clearances according to the design. The clearances are set one by one with the first pads, and the first pads can be exposed from the clearances.

[0007] The first layer of metal treatment involves immersion plating nickel-gold on the first pad. After the nickel-gold plating is completed, the first tape is removed, and gold is plated on the second pad. The remaining wires after the second pad is plated with gold are etched with an etching solution. Then, the dry film from the previous process is removed, and solder resist ink is applied to the areas on the circuit board that are not covered with solder resist ink, leaving solder resist openings on the second pad.

[0008] Apply the second layer of tape around the solder mask openings of the first and second pads, exposing both pads.

[0009] The second metal treatment involves gold plating on the first pad. After the first pad is gold-plated, the wires are removed with a knife. Nickel-gold plating is then performed on the second pad. After the second metal treatment is completed, the second tape is removed.

[0010] The third application of tape involves applying a third tape around the solder mask openings of the first and second pads. When applying the third tape, a clearance is pre-cut into the third tape before applying it to the circuit board. The third tape covers the edges of the first and second pads. The third tape is a high-temperature resistant tape.

[0011] Tin spraying involves passing the circuit board through a tin spraying device to cover both the first and second pads with a layer of tin. During the tin spraying process, the circuit board with the two metal layers is first placed in a drying oven to dry. After drying in the drying oven, the circuit board is then placed in an electrostatic dust removal box for dust removal.

[0012] Leveling: After the soldering is completed, hot air is used to level the solder paste. The hot air uses both confining and leveling air. The confining air is used to limit the solder paste from overflowing, and the leveling air is used to level the peaks after soldering.

[0013] Post-processing involves washing and drying the tin-plated circuit board.

[0014] According to an embodiment of the present invention, a comprehensive surface treatment process for circuit boards has at least the following beneficial effects: In the pre-processing stage, two different cover layers are fabricated on the same circuit board. The solder resist ink layer and the dry film layer are respectively located at corresponding positions on the circuit board, which can simultaneously satisfy the subsequent surface treatment of the first and second pads, eliminating the tediousness of separate processing and improving the efficiency of circuit board surface treatment; In the first step of applying adhesive tape, it is to cover the edge area of ​​the first pad covered by the solder resist layer so that the solder resist layer will not be damaged during nickel-gold plating. Since the gold-plated conductors of the second pad in the middle area of ​​the circuit board are difficult to remove, an anti-plating dry film is used to protect the non-gold-plated areas of the circuit board. The gold plating of the first pad and the immersion nickel-gold plating of the second pad are performed alternately, concentrating different surface treatments on a single circuit board. This ensures efficient production of the circuit board and improves its production efficiency. Finally, after both the first and second pads have undergone metal layer treatment, they are then tin-plated. This allows for the simultaneous tin-plating of two different circuit structures on the circuit board, greatly improving efficiency. In addition, electrostatic dust removal is used during tin-plating to prevent dust from contaminating the first and second pads and causing poor tin plating. Furthermore, constrained air and leveling air are used to level the solder paste, avoiding contact leveling and preventing damage to the solder layer.

[0015] According to some embodiments of the present invention, in the second tape application step, the second tape is configured as a rectangular strip tape, and the second tape is provided with mating steps. The second tapes are overlapped to cover the solder mask opening of the first pad and the surrounding area of ​​the solder mask opening of the second pad.

[0016] According to some embodiments of the present invention, in the second tape application step, after the second tape is applied, the tape is removed from the solder mask opening positions of the first pad and the second pad.

[0017] According to some embodiments of the present invention, when removing the first tape, a hot air blower is used to heat the first tape above it, and then a blade is used to scoop up the first tape, and then the first tape is dragged and torn off. The heat can soften the adhesive on the first tape, making it easier to peel off the first tape.

[0018] According to some embodiments of the present invention, in the first tape application and the second tape application steps, after the corresponding tape is applied, a pressure roller is used to roll back and forth on the tape. The pressure roller is equipped with an electric heating wire, which heats the adhesive on the tape, making the adhesive bond to the circuit board more tightly. The heated pressure roller can soften the adhesive in the tape when rolling, and under the pressure, the tape and the circuit board are bonded more tightly.

[0019] According to some embodiments of the present invention, in the pre-processing step, an anti-plating dry film is used, and the anti-plating dry film needs to be developed to leave space for the second pad.

[0020] According to some embodiments of the present invention, in the first metal processing step, when the wire is etched, a cotton swab is used to apply etching solution to the root of the wire and then repeatedly rubs it, thereby etching the wire off by friction and chemical etching.

[0021] According to some embodiments of the present invention, in the second metal processing step, a knife scrapes away the root of the conductor on the first pad along the edge of the circuit board, thereby breaking the conductor on the first pad.

[0022] According to some embodiments of the present invention, in the tin spraying step, after the film is formed, the circuit board is placed in a temperature chamber at 8-18°C for 10 minutes to increase the structural strength of the tin layer.

[0023] According to some embodiments of the present invention, in the post-processing step, absorbent paper is suspended on one side of the circuit board, and a cold air fan is used to blow on the other side, so that the cold air passes over the surface of the circuit board and the absorbent paper is used to absorb water vapor.

[0024] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0026] Figure 1 This is a schematic diagram of applying the first adhesive tape and dry film to the circuit board according to an embodiment of the present invention;

[0027] Figure 2 for Figure 1 The diagram shows a second tape being applied to a circuit board.

[0028] Figure 3 This is a diagram illustrating the second application of the second layer of tape.

[0029] Figure 4 This is a diagram illustrating how an air nozzle blows air into the solder paste to level it during the leveling process.

[0030] Figure 5 A schematic diagram of the rectangular second tape structure;

[0031] Figure 6 This is a diagram illustrating the application of the third layer of tape.

[0032] Circuit board 100, first pad 110, second pad 120;

[0033] 200 g of dry film, 300 g of first tape, 400 g of second tape, and 500 g of third tape. Detailed Implementation

[0034] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0035] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0036] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0037] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0038] Reference Figures 1 to 6 A comprehensive surface treatment process for circuit boards includes the following steps:

[0039] In the pre-process, after etching the circuit on the circuit board 100, solder resist ink is covered in the area of ​​the first pad 110 on the edge of the circuit board 100, and a solder resist opening is left in the first pad 110. Then, dry film 200 is covered in the area of ​​the second pad in the middle of the circuit board 100 where gold plating is not required, and a space for the second pad 120 is left in the second pad position.

[0040] For the first application of tape, apply the first tape 300 around the solder mask opening of the reserved first pad 110. After applying the first tape 300, the area of ​​the first pad 110 that needs to be plated with nickel gold will be exposed. When applying the first tape 300, cut out clearances according to the design. The clearances correspond one-to-one with the first pad 110. The first pad 110 can be exposed from the clearances. When applying the first tape 300, first wipe the area around the solder mask opening of the first pad 110 with alcohol, and then heat the adhesive side of the first tape 300 in hot air for 1 to 3 seconds before sticking it around the solder mask opening of the first pad 110.

[0041] The first metal treatment involves immersion plating nickel-gold onto the first pad 110. After the nickel-gold plating is completed, the first tape 300 is removed, and gold plating is performed on the second pad 120. The remaining conductors on the second pad 120 after gold plating are etched with an etching solution. Then, the dry film 200 from the previous process is removed, and solder resist ink is applied to the areas on the circuit board 100 that are not covered with solder resist ink, leaving a solder resist opening on the second pad 120. Before immersion plating nickel-gold, the surface of the first pad 110 is treated to remove the oxide layer. A mixed solution of ammonia and hydrochloric acid is used, and the surface of the first pad 110 is wiped 3 to 5 times with a cotton swab. Then, high-pressure water mist is used to spray away the residual acidic substances on the surface of the first pad 110 towards the edge of the circuit board.

[0042] The second application of tape involves applying the second tape 400 around the solder mask openings of the first pad 110 and the second pad 120, exposing both the first pad 110 and the second pad 120.

[0043] The second metal treatment involves gold plating on the first pad 110. After the first pad 110 is gold-plated, the wires are removed with a knife. Nickel-gold plating is then performed on the second pad 120. After the second metal treatment is completed, the second tape 400 is removed.

[0044] The third application of tape involves applying a third tape 500 around the solder mask openings of the first pad 110 and the second pad 120. When applying the third tape 500, a clearance is pre-cut in the third tape 500 before applying the tape to the circuit board 100. The third tape 500 covers the edges of the first pad 110 and the second pad 120. The third tape 500 is a high-temperature resistant tape.

[0045] Tin spraying involves passing the circuit board 100 through a tin spraying device to cover both the first pad 110 and the second pad 120 with a layer of tin. During the tin spraying process, the circuit board with the two metal layers is first placed in a drying oven. After the circuit board 100 is dried in the drying oven, it is then placed in an electrostatic dust removal box for dust removal.

[0046] Leveling: After the soldering is completed, hot air is used to level the solder paste. The hot air uses both confining and leveling air. The confining air is used to limit the solder paste from overflowing, and the leveling air is used to level the peaks after soldering.

[0047] Post-processing involves washing and drying the tin-plated circuit board 100.

[0048] In the pre-processing stage, two different cover layers are fabricated on the same circuit board 100. The solder resist ink layer and the dry film 200 layer are respectively located at corresponding positions on the circuit board 100, which can simultaneously meet the subsequent surface treatment of the first pad 110 and the second pad 120, eliminating the tedious process of separate processing and improving the efficiency of the surface treatment of the circuit board 100. The first step of applying tape is to cover the edge area of ​​the first pad 110 covered with the solder resist layer, so that the solder resist layer will not be damaged during the nickel-gold plating process. However, because the gold-plated conductors of the second pad 120 in the middle area of ​​the circuit board 100 are not suitable for gold plating... For the removal process, an anti-plating dry film 200 is used to protect the non-gold-plated areas on the circuit board 100. The gold plating of the first pad 110 and the immersion nickel-gold plating of the second pad 120 are performed alternately. Different surface treatments are concentrated on one circuit board 100, which not only ensures the effective production of the circuit board 100 but also improves its production efficiency. Finally, after the first pad 110 and the second pad 120 have undergone metal layer treatment, the first pad 110 and the second pad 120 are then tin-plated. Tin-plating of two different circuit structures can be completed on the circuit board 100 at one time, which greatly improves efficiency. It is understandable that the solder mask layer and dry film layer in the previous process exist simultaneously on the circuit board 100. This is because the first pad 110 is located at the edge of the circuit board 100. During gold plating, the gold-plated conductors can connect to the edge of the first pad 110, which can be removed later with a knife. However, the second pad 120 is inside the circuit board 100. If it is simply removed with a knife, it is easy to scratch the second pad 120. Therefore, an etching solution is needed to etch away the gold-plated conductors on the second pad. Thus, two different surface cover protection methods are needed to protect other circuits. Solder mask ink and tape are used around the first pad 110 to protect other circuits, and the circuit board 100 can also be partially covered with a solder mask layer. Dry film is needed to protect the second pad 120. The dry film can prevent the etching solution from damaging the circuit board and can also resist electroplating. The dry film used is an anti-electroplating dry film. It's understandable that solder paste application is a common process for circuit boards. Furthermore, during solder paste application, electrostatic dust removal is used to prevent dust from contaminating the first and second pads (110 and 120), which could hinder solder paste application. Additionally, constrained airflow and leveling airflow are used to level the solder paste, avoiding direct contact and preventing damage to the solder layer. The metal layer refers to the nickel-gold layer and the gold plating layer.

[0049] Reference Figure 2 , Figure 3 and Figure 5In the second tape application step, the second tape 400 is set as a rectangular strip tape, and the second tape 400 is provided with matching steps. The second tapes 400 are overlapped to cover the solder mask opening of the first pad 110 and the surrounding area of ​​the solder mask opening of the second pad 120. It can be understood that the rectangular strip tape is for easy application. Compared with the large-area tape that can cover the entire circuit board 100, the rectangular strip tape is easier to operate, improves the accuracy of tape application, reduces the influence of air bubbles, and avoids misalignment.

[0050] In some embodiments, in the second tape application step, after the second tape 400 is applied, the tape is removed from the solder mask openings of the first pad 110 and the second pad 120. It can be understood that when removing the tape from the solder mask openings, the tape at the solder mask openings can be cut with a knife first, and then the cut tape can be picked out with a knife.

[0051] In some embodiments, when removing the first tape 300, a hot air blower is used to heat the first tape 300 above it, and then a blade is used to lift the first tape 300, and then the first tape 300 is dragged and torn off. The heat can soften the adhesive on the first tape 300, making it easier to peel off the first tape 300.

[0052] In some embodiments, during the first and second tape application steps, after the corresponding tape is applied, a pressure roller is used to roll back and forth on the tape. The pressure roller is equipped with a heating wire, which heats the adhesive on the tape, making the adhesive bond more tightly to the circuit board 100. The heated pressure roller can soften the adhesive in the tape during rolling, and under pressure, the tape adheres more tightly to the circuit board 100.

[0053] In some embodiments, in the pre-processing steps, the dry film 200 uses an anti-electroplating dry film, and the dry film 200 needs to be developed to leave space for the second pad 120.

[0054] In some embodiments, during the first metal processing step, when the wire is being etched, a cotton swab is used to apply etching solution to the root of the wire and then repeatedly rubs it to etch the wire through friction and chemical etching.

[0055] In some embodiments, during the second metal processing step, a knife scrapes away the root of the wire on the first pad 110 along the edge of the circuit board 100, thereby breaking the wire on the first pad.

[0056] In some embodiments, during the tin plating step, after the film is formed, the circuit board 100 is placed in an oven at 8-18°C for 10 minutes to increase the structural strength of the tin layer.

[0057] In some embodiments, during the post-processing step, absorbent paper is suspended on one side of the circuit board 100, and a cold air blower is used to blow on the other side, so that the cold air passes over the surface of the circuit board 100. The absorbent paper is used to absorb water vapor. It is understood that the cold air blower is used because the solder layer cannot be subjected to excessive heat. If the solder layer is subjected to too much heat, it will decompose and will not protect the second pad and the first pad.

[0058] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A comprehensive surface treatment process for circuit boards, characterized in that, Includes the following steps: In the pre-process, after etching the circuit on the circuit board (100), solder resist ink is covered in the area of ​​the first pad (110) on the edge of the circuit board (100), and a solder resist opening is left in the first pad (110). Then, dry film (200) is covered in the area of ​​the second pad in the middle of the circuit board (100) where gold plating is not required, and a space for the second pad (120) is left in the second pad position. The first application of tape involves applying the first tape (300) around the solder mask opening of the reserved first pad (110). After applying the first tape (300), the area of ​​the first pad (110) that needs to be plated with nickel gold is exposed. When applying the first tape (300), the first tape (300) is cut out with clearances according to the design. The clearances correspond one-to-one with the first pad (110), and the first pad (110) can be exposed from the clearances. The first layer of metal processing involves immersion plating of nickel and gold on the first pad (110). After the nickel and gold plating is completed, the first tape (300) is removed, and gold is plated on the second pad (120). The wires remaining after the second pad (120) is plated with gold are etched with an etching solution. Then the dry film (200) from the previous process is removed, and solder resist ink is applied to the areas on the circuit board (100) that are not covered with solder resist ink, leaving solder resist openings on the second pad (120). The second application of tape involves applying the second tape (400) around the solder mask openings of the first pad (110) and the second pad (120). After the second tape (400) is applied, both the first pad (110) and the second pad (120) are exposed. The second metal treatment involves gold plating on the first pad (110). After the first pad (110) is gold-plated, the wires are removed with a knife. Nickel-gold plating is then performed on the second pad (120). After the second metal treatment is completed, the second tape (400) is removed. The third application of tape involves applying a third tape (500) around the solder mask openings of the first pad (110) and the second pad (120). When applying the third tape (500), a clearance is pre-cut in the third tape (500), and then the third tape (500) is applied to the circuit board (100). The third tape (500) covers the edges of the first pad (110) and the second pad (120). The third tape (500) is a high-temperature resistant tape. Tin spraying: The circuit board (100) is passed through the tin spraying device so that the first pad (110) and the second pad (120) are covered with a layer of tin. During the tin spraying process, the circuit board with the two metal layers is first placed in a drying oven. After the circuit board (100) is dried in the drying oven, the circuit board (100) is then placed in an electrostatic dust removal box for dust removal. Leveling: After the soldering is completed, hot air is used to level the solder paste. The hot air uses both confining and leveling air. The confining air is used to limit the solder paste from overflowing, and the leveling air is used to level the peaks after soldering. Post-processing involves washing and drying the tin-plated circuit board (100).

2. The circuit board comprehensive surface treatment process according to claim 1, characterized in that: In the second tape application step, the second tape (400) is set as a rectangular strip tape, and the second tape (400) is provided with mating steps. The second tapes (400) are overlapped to cover the solder mask opening of the first pad (110) and the surrounding area of ​​the solder mask opening of the second pad (120).

3. The circuit board comprehensive surface treatment process according to claim 2, characterized in that: In the second tape application step, after the second tape (400) is applied, the tape is removed from the solder mask openings of the first pad (110) and the second pad (120).

4. The circuit board comprehensive surface treatment process according to claim 1, characterized in that: When removing the first tape (300), use a hot air blower to heat the first tape (300) from above, then use a blade to lift the first tape (300), and then drag and tear off the first tape (300).

5. The circuit board comprehensive surface treatment process according to claim 1, characterized in that: In the first and second tape application steps, after the corresponding tape is applied, a pressure roller is used to roll back and forth on the tape. The pressure roller is equipped with a heating wire, which heats the adhesive on the tape, making the adhesive bond more tightly to the circuit board (100).

6. The circuit board comprehensive surface treatment process according to claim 1, characterized in that: In the aforementioned preprocessing steps, the dry film (200) uses an anti-plating dry film, which needs to be developed to leave space for the second pad (120).

7. The circuit board comprehensive surface treatment process according to claim 1, characterized in that: In the first metal processing step, when the wire is being etched, a cotton swab is used to apply etching solution to the root of the wire and then repeatedly rubs it, using friction and chemical etching to etch the wire off.

8. The circuit board comprehensive surface treatment process according to claim 1, characterized in that: In the second metal processing step, a knife is used to scrape off the root of the wire on the first pad (110) along the edge of the circuit board (100), thereby breaking the wire on the first pad.

9. The circuit board comprehensive surface treatment process according to claim 1, characterized in that: In the tin spraying step, after the film is formed, the circuit board (100) is placed in a temperature chamber at 8-18°C for 10 minutes to increase the structural strength of the tin layer.

10. The circuit board comprehensive surface treatment process according to claim 1, characterized in that: In the post-processing step, absorbent paper is suspended on one side of the circuit board (100), and a cold air blower is used to blow on the other side, so that the cold air passes over the surface of the circuit board (100) and the absorbent paper is used to absorb water vapor.

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