A PCB board for a prefabricated circuit and a manufacturing method thereof

Abstract

The present invention discloses a PCB board with prefabricated circuits and a manufacturing method thereof. The manufacturing method includes the following steps: covering a release film on the surface of a carrier board; covering a dry film on the surface of the release film and performing pattern transfer to open a window for the circuit pattern; electroplating the circuit pattern on the release film, and then removing the dry film to obtain a prefabricated circuit board; laminating the prefabricated circuit board with a core board through a prepreg to obtain a PCB preform; tearing off the carrier board and the release film of the PCB preform, and after performing solder mask printing treatment, obtaining the PCB board with prefabricated circuits. The present invention can greatly improve the manufacturing precision of circuits and the ability to manufacture fine circuits, improve the circuit yield rate of the PCB board, and can avoid the problem of too thin ink thickness at the shoulders of the circuits in the solder mask printing process.

Description

Technical Field

[0001] The present invention belongs to the technical field of PCB boards, and particularly relates to a PCB board with prefabricated circuits and a manufacturing method thereof. Background Art

[0002] The volume of electronic products is getting smaller and smaller, and the volume of PCB (printed circuit board) is also continuously developing in the direction of being small and dense.

[0003] At present, the general mass production line width and spacing (minimum line width and minimum spacing) ability of the traditional etching method is 3 mil / 3 mil. To further achieve 2 mil / 2 mil, or even 1.5 mil / 1.5 mil, the copper thickness needs to be reduced to 0.3 mil to be etched. However, when the copper thickness is reduced to 0.3 mil for etching, it is difficult to ensure the uniformity of the etching solution biting, resulting in a very low yield of the circuit. Therefore, it is very difficult to mass produce circuits with a line width and spacing below 3 mil / 3 mil.

[0004] In addition, in the prior art, the outer layer circuit is etched, so the outer layer circuit on the PCB board protrudes from the surface of the material. Therefore, the ink on both sides of the circuit will slide down during the solder mask printing, resulting in the solder mask ink thickness on the shoulders of the circuit being easily too thin, affecting the quality of the PCB board. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art, and provide a PCB board with prefabricated circuits and a manufacturing method thereof, which can greatly improve the manufacturing accuracy of the circuit and the ability to manufacture fine circuits, improve the circuit yield of the PCB board, and avoid the problem of too thin ink thickness on the shoulders of the circuit during the solder mask printing process.

[0006] The present invention provides the following technical solutions:

[0007] In the first aspect, a manufacturing method of a PCB board with prefabricated circuits is provided, including the following steps:

[0008] Cover a release film on the surface of the carrier board;

[0009] Cover a dry film on the surface of the release film and perform pattern transfer to open a window for the circuit pattern;

[0010] Electroplate the circuit pattern on the release film, and then remove the dry film to obtain a prefabricated circuit board;

[0011] Press the prefabricated circuit board with a core board through a prepreg to obtain a PCB preform;

[0012] Tear off the carrier board and the release film of the PCB preform, and after performing solder mask printing treatment, obtain a PCB board with prefabricated circuits.

[0013] Further, the carrier plate is a smooth and flat plate with a thickness of 0.5 - 3 mm, and the surface of the carrier plate is polished by a 2000 - mesh nylon brush to reduce the roughness of the carrier plate, facilitating the removal of the release film in the later stage.

[0014] Further, the release film is a conductive release film.

[0015] Further, the dry film is covered on the surface of the release film through a laminating machine, and pattern transfer is performed through an LDI exposure machine.

[0016] Further, the thickness of the dry film is greater than the thickness of the circuit pattern electroplated on the release film.

[0017] Further, the electroplating is copper electroplating.

[0018] Further, the prepreg is a prepreg with a high resin content, and the resin content is greater than 70%. When melted at high temperature, there is more liquid resin, facilitating the integration of the circuit pattern electroplated on the release film into the prepreg.

[0019] Further, the thickness of the prepreg is greater than twice the thickness of the circuit pattern electroplated on the release film.

[0020] Further, when manufacturing the PCB pre - fabricated board, the pre - fabricated circuit board is laminated on one or both sides of the core board through the prepreg; after lamination, the circuit pattern electroplated on the release film is embedded in the prepreg.

[0021] In a second aspect, a PCB board with pre - fabricated circuits is provided, which is prepared by using the method described in the first aspect.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. In the present invention, a release film is covered on the surface of the carrier plate, and then a dry film is covered. Utilizing the high resolution of the dry film, a high - precision fine circuit pattern opening is first fabricated through pattern transfer, and then a circuit is grown in the opening through electroplating, ensuring that the accuracy of the circuit pattern is consistent with the resolution of the dry film, reaching a line width and pitch level of 1 mil / 1 mil, greatly improving the circuit manufacturing accuracy and the ability to manufacture fine circuits, improving the circuit yield of the PCB board, and being beneficial to the mass production of the PCB board.

[0024] 2. In the present invention, the PCB pre - fabricated board is first manufactured, and then the PCB pre - fabricated board and the core board are laminated through the prepreg, enabling the circuit pattern on the PCB pre - fabricated board to be embedded in the prepreg. The surface of the prepreg is flat, so the solder mask ink is printed smoothly and is not prone to flowing, avoiding the problem of too thin ink thickness at the shoulders of the circuit during the solder mask printing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1It is the flowchart of manufacturing the PCB board of the prefabricated circuit in the embodiment of the present invention;

[0026] Figure 2 It is the schematic structural diagram of the release film covering the surface of the carrier board in the embodiment of the present invention;

[0027] Figure 3 It is the schematic structural diagram of the circuit pattern opened on the dry film in the embodiment of the present invention;

[0028] Figure 4 It is the schematic structural diagram of the circuit pattern electroplated on the release film in the embodiment of the present invention;

[0029] Figure 5 It is the schematic structural diagram of the prefabricated circuit board obtained after removing the dry film in the embodiment of the present invention;

[0030] Figure 6 It is the schematic structural diagram of the stacking of the prefabricated circuit board and the core board in the embodiment of the present invention;

[0031] Figure 7 It is the schematic structural diagram of the PCB prefabricated board obtained after lamination in the embodiment of the present invention;

[0032] Figure 8 It is the schematic structural diagram of the PCB prefabricated board after tearing off the carrier board and the release film in the embodiment of the present invention;

[0033] Figure 9 It is the schematic structural diagram of the PCB board of the prefabricated circuit obtained after solder mask printing in the embodiment of the present invention.

[0034] Numbers in the figure: carrier board 1, release film 2, dry film 3, circuit pattern 4, core board 5, solder mask ink 6. Detailed implementation manners

[0035] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0036] It should be noted that in the description of the present invention, the orientation or positional relationship indicated by the terms "front", "rear", "left", "right", "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention rather than requiring the present invention to be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation to the present invention.

[0037] Embodiment 1:

[0038] As Figure 1 shown, this embodiment provides a method for manufacturing a PCB board of a prefabricated circuit, and the steps are as follows:

[0039] Step 1: As shown in Figure 2 , a release film 2 is covered on the surface of the carrier plate 1.

[0040] The carrier plate 1 is a smooth and flat plate with a thickness of 0.5 - 3 mm, which can conduct electricity and is resistant to the corrosion of strong acids and strong alkalis; the carrier plate 1 can be a stainless steel plate, a copper plate, a copper clad laminate, etc. In this embodiment, the carrier plate 1 is a stainless steel plate with a thickness of 1 mm, and is polished by a 2000-mesh nylon brush before use. The release film 2 is a conductive release film and is resistant to the corrosion of strong acids and strong alkalis.

[0041] Step 2: As shown in Figure 3 , a dry film 3 is covered on the surface of the release film through a laminating machine, and then a pattern transfer is performed on the dry film 3 through an LDI exposure machine to open a window for the circuit pattern.

[0042] Step 3: As shown in Figure 4 , the carrier plate 1, the release film 2 and the dry film 3 are integrally immersed in an electroplating solution for copper electroplating, and a circuit pattern 4 is electroplated on the release film 2. The thickness of the electroplated circuit pattern is less than the thickness of the dry film in Step 2.

[0043] Step 4: As shown in Figure 5 , a sodium carbonate solution is used to remove the dry film 3 on the release film 2 to obtain a prefabricated circuit board.

[0044] Step 5: The prefabricated circuit board is laminated on one side or both sides of the core board through a prepreg to obtain a PCB preform.

[0045] As shown in Figure 6 , in this embodiment, the prefabricated circuit board, the prepreg, the core board 5, the prepreg and the prefabricated circuit board are stacked in sequence and then laminated. Among them, the prepreg is a cured sheet with a high resin content, and the resin content is greater than 70%. The thickness of the prepreg is more than twice the thickness of the circuit pattern electroplated on the release film. During lamination, the prepreg melts, so that the circuit pattern electroplated on the release film is embedded in the prepreg.

[0046] Step 6: As shown in Figure 8 , the carrier plates and the release films on both sides of the PCB preform are torn off to expose the circuit pattern.

[0047] Step 7: As shown in Figure 9 , solder resist ink 6 is printed on the circuit pattern to obtain a PCB board with a prefabricated circuit.

[0048] Example 2:

[0049] This embodiment provides a PCB board with a prefabricated circuit, which is prepared by the method described in Example 1.

[0050] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A manufacturing method of a PCB board with prefabricated circuits, characterized in that, it includes the following steps: Cover a release film on the surface of the carrier board, and the release film is a conductive release film; Cover a dry film on the surface of the release film and perform pattern transfer to open a window for the circuit pattern; Electroplate the circuit pattern on the release film, and the thickness of the electroplated circuit pattern is less than the thickness of the dry film, then remove the dry film to obtain a prefabricated circuit board; Press the prefabricated circuit board and the core board through a prepreg. The thickness of the prepreg is more than twice the thickness of the electroplated circuit pattern on the release film. When pressing, the prepreg melts. After pressing, the electroplated circuit pattern on the release film is embedded in the prepreg to obtain a prefabricated PCB board; Tear off the carrier board and the release film of the prefabricated PCB board to expose the circuit pattern. After the circuit pattern undergoes solder mask printing treatment, a PCB board with prefabricated circuits is obtained.

2. The manufacturing method of the PCB board with prefabricated circuits according to claim 1, characterized in that, the carrier board is a smooth and flat board with a thickness of 0.5 - 3 mm, and the surface of the carrier board is polished by a 2000 - mesh nylon brush.

3. The manufacturing method of the PCB board with prefabricated circuits according to claim 1, characterized in that, the dry film is covered on the surface of the release film by a laminator and pattern transfer is performed by an LDI exposure machine.

4. The manufacturing method of the PCB board with prefabricated circuits according to claim 1, characterized in that, the electroplating is copper electroplating.

5. The manufacturing method of the PCB board with prefabricated circuits according to claim 1, characterized in that, the prepreg is a high - resin - content cured sheet with a resin content greater than 70%.

6. The manufacturing method of the PCB board with prefabricated circuits according to claim 1, characterized in that, when manufacturing the prefabricated PCB board, the prefabricated circuit board is pressed on one side or both sides of the core board through a prepreg.

7. A PCB board with prefabricated circuits, characterized in that, it is prepared by using the method according to any one of claims 1 - 6.

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