Outer circuit manufacturing method suitable for dense circuit and circuit board

Abstract

The invention discloses an outer-layer circuit manufacturing method suitable for a dense circuit and a circuit board. The manufacturing method comprises the following steps: respectively dividing a gold plating area and a non-gold plating area on a C-surface copper foil and an S-surface copper foil of a working board; an effective circuit A is manufactured on the C-face copper foil, and an effective circuit B and a lead connected with a bonding pad in the effective circuit B are manufactured on the gold plating area of the S-face copper foil; after the lead is covered with the protective film A, the non-gold-plating areas of the C-face copper foil and the S-face copper foil are covered with protective films B; taking the non-gold plating area of the S-side copper foil as a conductor, and performing nickel-gold plating on the gold plating areas of the S-side copper foil and the C-side copper foil to form a nickel-gold layer; removing the protective film B and the protective film A; and manufacturing an effective circuit C on the non-gold-plating area of the S-surface copper foil, and removing the lead to complete the manufacturing of the outer circuit. The manufacturing method not only can ensure that the effective circuit on the S-surface copper foil is not deviated and high in precision, but also can ensure that the electrometallization is not abnormal, and meets the processing requirements of the circuit board.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit boards, and in particular to an outer layer circuit manufacturing method and a circuit board suitable for dense circuits. Background Art

[0002] Circuit boards are carriers that support electronic components and realize electrical connections. With the rapid development of high-end industries, the density of circuit boards is getting higher and higher, which also makes the processing of circuit boards more and more difficult. For example, when it is necessary to perform electroplating (i.e., nickel-gold electroplating) processing on dense circuit areas, due to the dense circuits, some areas on the circuit board cannot be laid out with electroplated gold leads, resulting in the electroplating processing cannot be carried out smoothly. If the processing sequence of electroplating first and then etching the circuit is followed, it may cause the circuits in the electroplated gold area and the circuits in the non-electroplated gold area to be open. Therefore, it is urgent to provide a circuit and electroplating method that can be applied to dense circuits. In view of this, the present invention is specially proposed. Summary of the invention

[0003] In order to overcome the above-mentioned defects, the present invention provides an outer layer circuit manufacturing method and a circuit board suitable for dense circuits. The manufacturing method is simple, reasonable and flexible to operate. It can ensure that the effective circuit on the S-side copper foil has no deviation and high precision, and can ensure that the electrometallurgical processing has no abnormality and high processing quality, which well meets the processing requirements of circuit boards with high circuit density.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a method for manufacturing an outer layer circuit suitable for dense circuits, comprising the following manufacturing steps:

[0005] S1: providing a work board, wherein the work board is provided with a C-side copper foil and an S-side copper foil, wherein the C-side copper foil and the S-side copper foil are respectively divided into an electroplated gold area and a non-electroplated gold area;

[0006] S2: making an effective circuit A on the C-side copper foil, and making an effective circuit B and leads connected to the pads in the effective circuit B on the electroplated gold area of ​​the S-side copper foil;

[0007] S3: After coating the protective film A on the lead, coating the non-electrometallurgical areas of the C-side copper foil and the S-side copper foil with protective films B respectively;

[0008] S4: using the non-electro-gold area of ​​the S-side copper foil as a conductor, electroplating nickel-gold on the S-side copper foil and the electro-gold area of ​​the C-side copper foil to form a nickel-gold layer;

[0009] S5: removing the protective film B and the protective film A;

[0010] S6: an effective circuit C is produced on the non-electrometallurgical area of ​​the S-side copper foil, and the lead is removed, thus completing the production of the outer layer circuit.

[0011] As a further improvement of the present invention, in the above S2, the working board is subjected to pre-coating treatment, anti-corrosion photosensitive dry film coating, exposure, development, etching and film stripping processing in sequence, so as to etch the effective circuit A on the entire surface of the C-side copper foil, and etch the effective circuit B and the lead on the electroplating area of ​​the S-side copper foil.

[0012] As a further improvement of the present invention, in the above S3, the protective film A is made of anti-electrochemical gold ink; and the protective film B is made of anti-plating photosensitive dry film.

[0013] As a further improvement of the present invention, after the anti-electrometallurgical ink is printed on the lead and cured, the C-side copper foil and the S-side copper foil are respectively coated with an anti-plating photosensitive dry film, exposed and developed, so as to realize opening windows to expose the electrometallurgical areas on the C-side copper foil and the S-side copper foil, and at the same time, the anti-plating photosensitive dry film is respectively coated on the non-electrometallurgical areas of the C-side copper foil and the S-side copper foil.

[0014] As a further improvement of the present invention, in the above S6, the S-side copper foil is subjected to pre-coating treatment, anti-corrosion photosensitive dry film coating, exposure, development, etching and film stripping in sequence, so as to etch out the effective circuit C on the non-electrometallurgical area of ​​the S-side copper foil and etch away the lead.

[0015] As a further improvement of the present invention, in the above S1, the working board adopts a multilayer board that has undergone the processes of inner layer circuit production, double-sided lamination and interlayer conduction, and has double-sided outer copper foil.

[0016] As a further improvement of the present invention, an AOI inspection process is respectively provided between S2 and S3 and after the completion of S6.

[0017] As a further improvement of the present invention, after completing the above S6, solder masking, molding, finished product testing, finished product inspection and packaging processes are sequentially performed to obtain a circuit board.

[0018] The present invention also provides a circuit board, which is manufactured by using the outer layer circuit manufacturing method applicable to dense circuits as described in the present invention.

[0019] The beneficial effects of the present invention are as follows: 1) Through technical innovation, the present invention adopts the processing method of: "First, an effective circuit is produced on the entire surface of the C-side copper foil and the electroplated gold area of ​​the S-side copper foil, then electroplating is performed, and finally an effective circuit is produced on the non-electroplated gold area of ​​the S-side copper foil". This can not only ensure that the effective circuit on the S-side copper foil has no deviation and high precision, but also ensure that the electroplating is without abnormalities, which well meets the processing requirements of circuit boards with high circuit density. 2) While the present invention produces an effective circuit B on the electroplated gold area of ​​the S-side copper foil, it also produces a lead connected to the pad in the effective circuit B; in this way, when electroplating is performed in the post-process, by first covering the lead with anti-electroplating gold ink, the problem of gold seepage near the pad can be effectively prevented, ensuring that the electroplating is carried out smoothly and improving the processing quality of the electroplating. 3) The production method provided by the present invention is simple, reasonable, flexible in operation, easy to implement in production, and the resulting circuit board has a high yield rate and good quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a process flow chart of the outer layer circuit manufacturing method suitable for dense circuits. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0022] Embodiment 1:

[0023] Please see attached Figure 1 As shown, this embodiment 1 provides a method for manufacturing an outer layer circuit suitable for dense circuits, including the following manufacturing steps:

[0024] S1: Provide a work board, wherein the work board is provided with a C-side copper foil and an S-side copper foil, wherein the C-side copper foil and the S-side copper foil are respectively divided into a gold-plated area and a non-gold-plated area, and the gold-plated area on the C-side copper foil is at least electrically connected to the gold-plated area on the S-side copper foil through a conductive hole.

[0025] Specifically, in this embodiment 1, the working board preferably adopts a multilayer board that has undergone processes such as inner layer circuit production (producing inner layer circuits), double-sided lamination build-up layers (including at least insulation build-up layers) and interlayer conduction (producing through holes), and has double-sided outer copper foil (i.e., the above-mentioned C-side copper foil and S-side copper foil).

[0026] Note: ① Since the focus of this application is to improve and innovate the method of making outer layer circuits, the processes such as "inner layer circuit production, double-sided lamination and interlayer conduction" are not described in detail. The production needs can be met by adopting conventional technical means in the field of circuit board processing. In addition, this application does not restrict the number of layers and types of multilayer boards, which can be determined according to product design requirements. ② C-side and S-side are common terms in the field of circuit board technology. C-side refers to the component side, and S-side refers to the solder side.

[0027] S2: an effective circuit A is fabricated on the C-side copper foil, and an effective circuit B and leads connected to pads in the effective circuit B are fabricated on the electroplated gold region of the S-side copper foil.

[0028] Specifically, the specific manufacturing method of the above-mentioned S2 is: the working board is subjected to pre-coating treatment, anti-corrosion photosensitive dry film coating, exposure, development, etching and film stripping processing in sequence, so as to etch the effective circuit A on the entire surface of the C-side copper foil, and etch the effective circuit B and the lead on the electroplating area of ​​the S-side copper foil.

[0029] Among them, the above-mentioned "pre-coating treatment, coating of anti-corrosion photosensitive dry film, exposure, development, etching and film stripping" processing steps are all common technical means in the field of circuit board processing, so they are not described in detail here, but only briefly explained as follows:

[0030] ① Pre-lamination treatment: ceramic grinding, cleaning and drying are performed on the working board in sequence to enhance the bonding force between the anti-corrosion photosensitive dry film and the C-side copper foil and the S-side copper foil in the subsequent process.

[0031] ② Laminating with anti-corrosion photosensitive dry film: Laminating the anti-corrosion photosensitive dry film on the C-side copper foil and the S-side copper foil. Furthermore, the laminating operation can be carried out by a vacuum laminating machine, which has high flatness and can ensure strong bonding between the anti-corrosion photosensitive dry film and the board surface.

[0032] ③Exposure and development: Exposure is to expose part of the area of ​​the anti-etching photosensitive dry film according to the working data of the circuit board; development is to remove the unexposed area of ​​the anti-etching photosensitive dry film. Furthermore, the exposure operation can be carried out by LDI exposure machine, which has high exposure accuracy and accurate alignment.

[0033] ④ Etching and film stripping: Etching is to remove the portions of the C-side copper foil and the S-side copper foil respectively exposed outside the anti-etching photosensitive dry film; film stripping is to remove the anti-etching photosensitive dry film using a strong alkaline solution; then the effective circuit A, the effective circuit B and the lead can be obtained.

[0034] In addition, after the effective circuit A, effective circuit B and lead wires are manufactured, AOI inspection of the manufactured effective circuits and lead wires is also required by an optical scanning method.

[0035] S3: After the protective film A is coated on the lead, protective films B are respectively coated on the non-electrometallurgical areas of the C-side copper foil and the S-side copper foil.

[0036] Specifically, the specific production method of the above-mentioned S3 is: first, anti-electrometallurgical gold ink (that is, the protective film A) is printed on the lead by screen printing technology, and after curing, the C-side copper foil and the S-side copper foil are respectively coated with an anti-plating photosensitive dry film, exposed and developed, so as to realize opening windows to expose the electrometallurgical gold areas on the C-side copper foil and the S-side copper foil, and at the same time, an anti-plating photosensitive dry film (that is, the protective film B) is also coated on the non-electrometallurgical gold areas of the C-side copper foil and the S-side copper foil.

[0037] Note: ① By printing the anti-electrolytic gold ink on the lead, the problem of gold seepage near the pad can be effectively prevented during the subsequent nickel-gold electroplating process. ② The specific processing method of the "anti-plating photosensitive dry film, exposure and development" process described in S3 above can refer to the corresponding content in S2 above, so it will not be repeated here.

[0038] S4: using the non-electro-gold area of ​​the S-side copper foil as a conductor, electroplating nickel-gold on the electro-gold areas of the S-side copper foil and the C-side copper foil to form a nickel-gold layer.

[0039] Note: ① When performing electroplating nickel-gold, the nickel layer is usually plated first and then the gold layer. This is a conventional technical means in the field of circuit board processing, so it will not be described in detail here. ② It can be understood that the nickel-gold layer is formed on the effective circuit (including the pad) in the electroplating gold area.

[0040] S5: removing the protective film B and the protective film A by using a film stripping liquid.

[0041] S6: an effective circuit C is produced on the non-electrometallurgical area of ​​the S-side copper foil, and the lead is removed, thus completing the production of the outer layer circuit.

[0042] Specifically, the specific manufacturing method of the above-mentioned S6 is: the S-side copper foil is subjected to pre-coating treatment, anti-corrosion photosensitive dry film coating, exposure, development, etching and film stripping in sequence, so as to etch out the effective circuit C on the non-electrometallurgical area of ​​the S-side copper foil and etch away the lead at the same time.

[0043] Note: The specific processing methods of the steps of "pre-coating treatment, coating with anti-corrosion photosensitive dry film, exposure, development, etching and film stripping" described in the above S6 can be referred to the corresponding contents in the above S2, so they will not be repeated here.

[0044] In addition, after the effective circuit C is manufactured, an AOI inspection is performed on the effective circuit using an optical scanning method.

[0045] S7: After completing the above S6, conventional solder masking, molding, finished product testing, finished product inspection and packaging processes are carried out in sequence to obtain a circuit board.

[0046] From the above, it can be seen that 1) the present invention, through technical innovation, adopts the processing method of: "first produce the effective circuit on the entire surface of the C-side copper foil and the electroplated gold area of ​​the S-side copper foil, then perform electroplating, and finally produce the effective circuit on the non-electroplated gold area of ​​the S-side copper foil". It can not only ensure that the effective circuit on the S-side copper foil has no deviation and high precision, but also ensure that the electroplating is without abnormalities, which well meets the processing requirements of circuit boards with high circuit density. 2) The present invention not only produces an effective circuit B on the electroplated gold area of ​​the S-side copper foil, but also produces a lead connected to the pad in the effective circuit B; in this way, when electroplating is performed in the post-process, by first covering the lead with anti-electroplating gold ink, the problem of gold seepage near the pad can be effectively prevented, ensuring that the electroplating is carried out smoothly and improving the processing quality of the electroplating. 3) The production method provided by the present invention is simple, reasonable, flexible in operation, easy to implement in production, and the resulting circuit board has a high yield and good quality.

[0047] Embodiment 2:

[0048] This embodiment 2 provides a circuit board, which is manufactured using the outer layer circuit manufacturing method suitable for dense circuits described in the above embodiment 1.

[0049] It can be seen from the above-mentioned embodiment 1 that the circuit board has a high yield and good quality.

[0050] Note: The suffixes "A", "B", "C", etc. (such as effective circuit A, effective circuit B, effective circuit C, etc.) of the component names in this specification are only for the convenience of description and are not used to limit the scope of implementation of the patent of this invention.

[0051] Many specific details are described in the above description to facilitate a full understanding of the present invention. However, the above description is only a preferred embodiment of the present invention. The present invention can be implemented in many other ways different from those described herein, so the present invention is not limited to the specific implementation disclosed above. At the same time, any person familiar with the art can make many possible changes and modifications to the technical solution of the present invention using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A method for making an outer layer circuit suitable for dense circuits, characterized in that: The production steps include: S1: providing a work board, wherein the work board is provided with a C-side copper foil and an S-side copper foil, wherein the C-side copper foil and the S-side copper foil are respectively divided into an electroplated gold area and a non-electroplated gold area; S2: making an effective circuit A on the C-side copper foil, and making an effective circuit B and leads connected to the pads in the effective circuit B on the electroplating area of ​​the S-side copper foil; S3: After coating the protective film A on the lead, coating the non-electrometallurgical regions of the C-side copper foil and the S-side copper foil with protective films B respectively; S4: using the non-electro-gold area of ​​the S-side copper foil as a conductor, electroplating nickel-gold on the S-side copper foil and the electro-gold area of ​​the C-side copper foil to form a nickel-gold layer; S5: removing the protective film B and the protective film A; S6: an effective circuit C is produced on the non-electrometallurgical area of ​​the S-side copper foil, and the lead is removed, thus completing the production of the outer layer circuit.

2. The outer layer circuit manufacturing method suitable for dense circuits according to claim 1, characterized in that: In the above S2, the working board is subjected to pre-coating treatment, anti-corrosion photosensitive dry film coating, exposure, development, etching and film stripping processing in sequence, so as to etch the effective circuit A on the entire surface of the C-side copper foil, and etch the effective circuit B and the lead on the electroplating area of ​​the S-side copper foil.

3. The outer layer circuit manufacturing method suitable for dense circuits according to claim 1, characterized in that: In the above S3, the protective film A is made of anti-electrochemical gold ink; the protective film B is made of anti-plating photosensitive dry film.

4. The outer layer circuit manufacturing method suitable for dense circuits according to claim 3 is characterized in that: After the anti-electrometallurgical ink is printed on the lead and cured, the C-side copper foil and the S-side copper foil are respectively coated with an anti-plating photosensitive dry film, exposed and developed, so as to open windows to expose the electrometallurgical areas on the C-side copper foil and the S-side copper foil, and at the same time, the anti-plating photosensitive dry film is respectively coated on the non-electrometallurgical areas of the C-side copper foil and the S-side copper foil.

5. The outer layer circuit manufacturing method suitable for dense circuits according to claim 1, characterized in that: In the above S6, the S-side copper foil is subjected to pre-coating treatment, anti-corrosion photosensitive dry film coating, exposure, development, etching and film stripping in sequence, so as to etch out the effective circuit C on the non-electrometallurgical area of ​​the S-side copper foil and etch away the lead.

6. The outer layer circuit manufacturing method suitable for dense circuits according to claim 1, characterized in that: In the above S1, the working board adopts a multilayer board which has undergone the processes of inner layer circuit making, double-sided lamination and layer building, and interlayer conduction, and has double-sided outer copper foil.

7. The outer layer circuit manufacturing method suitable for dense circuits according to claim 1, characterized in that: An AOI inspection process is provided between S2 and S3 and after S6 is completed.

8. The outer layer circuit manufacturing method suitable for dense circuits according to claim 1, characterized in that: After completing the above S6, solder masking, molding, finished product testing, finished product inspection and packaging processes are carried out in sequence to obtain the circuit board.

9. A circuit board, characterized in that: The outer layer circuit is manufactured by the manufacturing method suitable for dense circuits as described in any one of claims 1 to 8.

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