A method for manufacturing circuits of back-drilled plug-hole circuit boards

Abstract

The present invention discloses a circuit manufacturing method for a back-drilled plugged circuit board, comprising the following steps: providing a multilayer board with back-drilled holes, and plugging the back-drilled holes with resin; pasting dry film on the front and back of the multilayer board, and opening windows in the dry film at the openings of the back-drilled holes, and the aperture of the dry film openings is larger than the aperture of the back-drilled holes; making a first circuit pattern on the front and back of the multilayer board, and copper-tin plating the multilayer board; performing laser milling on the multilayer board to mill out a second circuit pattern at the dry film openings of the multilayer board, and connecting the second circuit pattern with the first circuit pattern; performing alkaline etching on the multilayer board to etch part of the surface copper at the dry film openings of the multilayer board; stripping the film; performing alkaline etching on the multilayer board to etch the surface copper on the front and back of the multilayer board. The method solves the problem of copper-tin plating caused by the loose adhesion of the dry film at the back-drilled holes, and improves the success rate of circuit manufacturing after back-drilling plugging.

Description

Technical Field

[0001] The invention relates to the technical field of circuit board manufacturing, and in particular to a circuit manufacturing method for a back-drilled plug-hole circuit board. Background Art

[0002] With the development of electronic industry integration, the size of electronic products has become smaller and smaller, the density of electronic components has become larger and larger, and the back drilling process of PCB has become more and more common. At present, some products have the demand to make circuits after back drilling the holes with resin. After back drilling the holes with resin, in order to ensure the effect of resin plugging the holes, the end face of the resin is better to be higher than the end face of the circuit board. In the subsequent process of making circuit graphics, it is necessary to apply dry film on the end face of the circuit board. The height difference between the end face of the resin and the end face of the circuit board will make it impossible for the dry film to be completely applied to the end face of the circuit board. The applied dry film is not firm, and there is a gap between the dry film and the end face of the circuit board. When copper-tin plating, copper-tin will penetrate from the gap, thereby reducing the success rate of circuit production. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, an object of the present invention is to provide a method for manufacturing a circuit of a back-drilled via circuit board, which can improve the success rate of circuit manufacturing after back-drilling vias.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows: a method for manufacturing a circuit of a back-drilled plugged circuit board, comprising the following steps: S100, providing a multilayer board with back-drilled holes, and plugging the back-drilled holes with resin; S200, pasting a dry film on the front and back of the multilayer board, and opening a window in the dry film at the opening of the back-drilled hole, and the aperture of the dry film opening is larger than the aperture of the back-drilled hole; S300, manufacturing a first circuit pattern on the front and back of the multilayer board, and copper-tin plating the multilayer board; S400, performing laser milling on the multilayer board to mill out a second circuit pattern at the dry film opening of the multilayer board, and connecting the second circuit pattern with the first circuit pattern; S500, performing alkaline etching on the multilayer board to etch part of the surface copper at the dry film opening of the multilayer board; S600, stripping the film to remove the dry film in step S200; S700, performing alkaline etching on the multilayer board to etch the surface copper on the front and back of the multilayer board.

[0005] Compared with the prior art, the beneficial effect of the present invention is that after the back drilling is performed to plug the hole with resin, when the dry film is pasted on the front and back of the multilayer board, the dry film is opened around the back drilling hole, and the first circuit pattern is first made at the position where the dry film is covered on the multilayer board, and then the copper-tin plating treatment is performed. Since there is no circuit pattern at the position where the dry film window is opened, only the surface copper is plated at the position where the dry film window is opened during the copper-tin plating treatment, and there is no situation of damaging the circuit pattern at that position. After that, the second circuit pattern is made at the position where the dry film window is opened by laser milling, and the second circuit pattern is connected to the first circuit pattern, so as to obtain the required circuit pattern file. After the required circuit pattern file is made, an alkaline etching is first performed to remove the surface copper plated at the dry film window in step S300. At this time, the copper thickness at the dry film window is consistent with that at the dry film pasting position. Finally, the dry film is removed, and the multilayer board is subjected to an alkaline etching again, so as to etch the surface copper on the front and back of the multilayer board, and finally complete the circuit production on the entire circuit board. Therefore, when making circuits, this method performs dry film windowing at the back-drilled holes, and adopts two different processes for the dry film coating and the dry film windowing to make circuits, which can avoid the mutual influence of the two processes when making circuits, and finally solves the problem of copper-tin plating caused by the loose coating of the dry film at the back-drilled holes, thereby improving the success rate of circuit production after back-drilling and plugging.

[0006] The circuit manufacturing method of the above-mentioned back-drilled plugged circuit board, step S100 includes the following steps: S110, providing an upper board, a semi-cured sheet and a lower board, stacking the upper board, the semi-cured sheet and the lower board in sequence from top to bottom, and obtaining a multi-layer board through a lamination process; S120, making a first metallized hole in the multi-layer board, and the first metallized hole is a through hole; S130, making a back-drilled hole in the upper board, the back-drilled hole is coaxial with the first metallized hole, and the hole diameter is larger than the first metallized hole; S140, plugging the back-drilled hole with resin; wherein the upper end surface of the upper board is the back side of the multi-layer board.

[0007] The above-mentioned circuit manufacturing method of the back-drilled plug-hole circuit board, the step S120 includes the following steps: S121, drilling a first hole position on the multilayer board, and the first hole position is a through hole; S122, copper plating the multilayer board to plate a copper layer on the inner wall of the first hole position, thereby obtaining a first metallized hole.

[0008] The circuit manufacturing method of the back-drilled plugged circuit board mentioned above, after the step S140, also includes the following steps: S150, performing copper reduction treatment on the multilayer board to remove part of the surface copper on the front and back sides of the multilayer board; S160, drilling a second hole position on the multilayer board, and the second hole position is a through hole; S170, performing copper plating treatment on the multilayer board to plate a copper layer on the inner wall of the second hole position, thereby obtaining a second metallized hole.

[0009] In the above-mentioned method for manufacturing circuits of a back-drilled plugged via circuit board, in the step S200, the aperture of the dry film opening is 12 mil larger than the aperture of the back-drilled hole.

[0010] In the above-mentioned method for manufacturing circuits of back-drilled plugged via circuit boards, after step S700, the multilayer board is further subjected to outer layer AOI, surface treatment, performance testing, edge milling, final inspection and packaging.

[0011] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a longitudinal cross-sectional view of a circuit board according to an embodiment of the present invention;

[0013] Figure 2 A top view of a circuit board after a first circuit pattern is produced according to an embodiment of the present invention;

[0014] Figure 3 This is a top view of the circuit board after the second circuit pattern is manufactured according to the embodiment of the present invention.

[0015] Description of the accompanying drawings: 100 multilayer board, 110 upper board, 120 prepreg, 130 lower board, 140 first metallized hole, 150 back drilled hole, 160 second metallized hole, 170 first circuit pattern, 180 second circuit pattern. DETAILED DESCRIPTION

[0016] The embodiments of the present invention are described in detail below. Figures 1 to 3 The embodiment of the present invention provides a method for manufacturing a circuit of a back-drilled plug-hole circuit board, wherein the longitudinal cross-sectional view of the circuit board is as shown in FIG. Figure 1 As shown, the following steps are included:

[0017] S100, providing a multilayer board 100 having back-drilled holes 150, and plugging the back-drilled holes 150 with resin;

[0018] S200, affixing dry film on the front and back of the multilayer board 100, and performing window opening on the dry film at the opening of the back-drilled hole 150, wherein the aperture of the dry film window opening is larger than the aperture of the back-drilled hole 150. In this step, the part plugged with resin is not covered with dry film, and the dry film is not affected by the height difference therein when affixing the dry film, so that the dry film can be completely attached to the front and back of the multilayer board 100;

[0019] S300, making a first circuit pattern 170 on the front and back of the multilayer board 100, and copper-tin plating the multilayer board 100. Since the dry film applied in step S200 is completely attached to the front and back of the multilayer board 100, after the first circuit pattern 170 is made, in step S300, when copper-tin plating is performed, no infiltration plating will occur. Since no circuit pattern is made at the position where the dry film has a window, only copper will be plated at the position where the dry film has a window, and there will be no situation of damaging the circuit pattern at that position. Specifically, the first circuit pattern 170 can be made by external light imaging. The first circuit pattern 170 made is as follows: Figure 2 As shown;

[0020] S400, performing laser milling processing on the multilayer board 100 to mill out the second circuit pattern 180 at the dry film window of the multilayer board 100, and connect the second circuit pattern 180 with the first circuit pattern 170, such as Figure 3 As shown, the line diagram after connection is the line diagram file required by the customer;

[0021] S500, alkaline etching is performed on the multilayer board 100 to etch part of the surface copper at the dry film window opening of the multilayer board 100. Since in step S300, surface copper is plated at the position of the dry film window opening when copper tin is plated, the copper thickness here is greater than the copper thickness at other positions. Therefore, alkaline etching is first performed in step S500 to etch part of the surface copper at the dry film window opening, so that the surface copper here is consistent with the surface copper thickness at other positions of the multilayer board 100;

[0022] S600, film stripping to remove the dry film in step S200;

[0023] S700, alkaline etching is performed on the multilayer board 100 to etch the surface copper on the front and back sides of the multilayer board 100. In step S500, part of the surface copper at the dry film opening has been etched. Therefore, in step S700, it can be ensured that the excess surface copper on the multilayer board 100 is completely etched to avoid short circuit problems caused by incomplete etching, and finally the desired circuit pattern is obtained.

[0024] Compared with the prior art, the beneficial effect of the present invention is that after the back-drilled hole 150 is plugged with resin, when the front and back sides of the multilayer board 100 are covered with dry film, the back-drilled hole 150 is opened with dry film, and the first circuit pattern 170 is first made at the position where the multilayer board 100 covers the dry film, and then copper-tin plating is performed. Since there is no circuit pattern at the position where the dry film window is opened, only the surface copper is plated at the position where the dry film window is opened during the copper-tin plating process, and there is no situation where the circuit pattern at that position is damaged. After that, the second circuit pattern 180 is made at the position where the dry film window is opened by laser milling, and the second circuit pattern 180 is connected to the first circuit pattern 170, so as to obtain the required circuit pattern file. After the required circuit pattern file is prepared, alkaline etching is first performed to remove the surface copper plated at the dry film window in step S300. At this time, the copper thickness at the dry film window is consistent with that at the position where the dry film is pasted. Finally, the dry film is removed, and the multilayer board 100 is etched with alkaline again, so as to etch the copper on the front and back sides of the multilayer board 100, and finally complete the circuit production on the entire circuit board. Therefore, when producing the circuit, the method performs a dry film window opening at the back-drilled hole 150, and adopts two different processes for the dry film coating and the dry film window opening to produce the circuit, and can avoid the mutual influence of the two processes when producing the circuit, and finally solves the problem of copper-tin plating caused by the loose coating of the dry film at the back-drilled hole 150, and improves the success rate of circuit production after back-drilling and plugging.

[0025] Specifically, in some embodiments, step S100 includes the following steps:

[0026] S110, providing an upper plate 110, a prepreg 120 and a lower plate 130, stacking the upper plate 110, the prepreg 120 and the lower plate 130 from top to bottom, and obtaining a multilayer plate 100 through a lamination process;

[0027] S120, making a first metallized hole 140 in the multilayer board 100, and the first metallized hole 140 is a through hole;

[0028] S130, making a back-drilled hole 150 in the upper layer board 110, the back-drilled hole 150 is coaxial with the first metallized hole 140, and the hole diameter is larger than the first metallized hole 140, when the back-drilled hole 150 is drilled, the metallized layer on the upper part of the first metallized hole 140 in step S120 is removed;

[0029] S140 , plugging the back-drilled holes 150 with resin; wherein the upper end surface of the upper layer board 110 is the back surface of the multilayer board 100 .

[0030] Specifically, the step S120 includes the following steps:

[0031] S121, drilling a first hole on the multilayer board 100, wherein the first hole is a through hole;

[0032] S122 , performing copper plating treatment on the multilayer board 100 to plate a copper layer on the inner wall of the first hole position, thereby obtaining a first metallized hole 140 .

[0033] Specifically, after step S140, the following steps are also included:

[0034] S150, performing copper reduction treatment on the multilayer board 100 to remove part of the copper on the front and back sides of the multilayer board 100. In step S122, when the multilayer board 100 is subjected to copper deposition treatment, a copper layer of a certain thickness will be coated on the front and back sides of the multilayer board 100. Therefore, in step S150, the multilayer board 100 is first subjected to copper reduction treatment to reduce the copper thickness of the multilayer board 100, so as to avoid excessive copper thickness of the multilayer board 100 during copper deposition treatment after step S170;

[0035] S160, drilling a second hole on the multilayer board 100, wherein the second hole is a through hole;

[0036] S170, copper plating is performed on the multilayer board 100 to plate a copper layer on the inner wall of the second hole position, thereby obtaining a second metallized hole 160. After steps S150 to S170, a second metallized hole 160 can be made on the multilayer board 100. Figure 1 The circuit board shown has two metallized holes, and a coaxial non-metallized back-drilled hole 150 is provided on the upper side of one of the metallized holes.

[0037] Specifically, in step S200, the aperture of the dry film opening is 12 mil larger than the aperture of the back-drilled hole 150 to ensure that there is enough spacing between the dry film and the resin plug hole to ensure that the dry film is iron-fast, and also to reserve enough space for making the second circuit pattern 180. Specifically, after step S700, the multilayer board 100 is also subjected to outer layer AOI, surface treatment, performance test, edge milling, final inspection and packaging.

[0038] It should be noted that in the description of the present invention, if there are any orientation descriptions, such as up, down, front, back, left, right, etc., the orientations or positional relationships indicated are all based on the orientations or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and cannot be understood as a limitation on the present invention.

[0039] In the description of the present invention, "several" means one or more, "more" means two or more, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used to distinguish the technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0040] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0041] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for manufacturing a circuit of a back-drilled plug-hole circuit board, characterized in that: The steps include: S100, providing a multilayer board (100) with back-drilled holes (150), and plugging the back-drilled holes (150) with resin; S200, affixing a dry film on the front and back sides of the multilayer board (100), and performing window opening on the dry film at the opening of the back-drilled hole (150), wherein the aperture of the dry film window opening is larger than the aperture of the back-drilled hole (150); S300, making a first circuit pattern (170) on the front and back sides of the multilayer board (100), and performing a copper-tin plating process on the multilayer board (100); S400, performing laser milling processing on the multilayer board (100) to mill out a second circuit pattern (180) at a dry film window opening of the multilayer board (100), and connecting the second circuit pattern (180) to the first circuit pattern (170); S500, performing alkaline etching on the multilayer board (100) to etch a portion of the surface copper at the dry film window opening of the multilayer board (100); S600, film stripping to remove the dry film in step S200; S700, performing alkaline etching on the multilayer board (100) to etch the copper surfaces on the front and back sides of the multilayer board (100).

2. The method for manufacturing a circuit of a back-drilled via circuit board according to claim 1, characterized in that: The step S100 includes the following steps: S110, providing an upper plate (110), a prepreg (120) and a lower plate (130), stacking the upper plate (110), the prepreg (120) and the lower plate (130) in sequence from top to bottom, and performing a lamination process to obtain a multilayer plate (100); S120, making a first metallized hole (140) in the multilayer board (100), wherein the first metallized hole (140) is a through hole; S130, making a back-drilled hole (150) on the upper layer board (110), wherein the back-drilled hole (150) is coaxial with the first metallized hole (140) and has a larger hole diameter than the first metallized hole (140); S140, plugging the back-drilled hole (150) with resin; The upper end surface of the upper plate (110) is the back surface of the multilayer plate (100).

3. The method for manufacturing a circuit of a back-drilled via circuit board according to claim 2, characterized in that: The step S120 includes the following steps: S121, drilling a first hole on the multilayer board (100), wherein the first hole is a through hole; S122, performing copper plating on the multilayer board (100) to plate a copper layer on the inner wall of the first hole position, thereby obtaining a first metallized hole (140).

4. The method for manufacturing a circuit of a back-drilled via circuit board according to claim 3, characterized in that: After step S140, the following steps are also included: S150, performing copper reduction processing on the multilayer board (100) to remove part of the surface copper on the front and back sides of the multilayer board (100); S160, drilling a second hole on the multilayer board (100), wherein the second hole is a through hole; S170, performing copper plating on the multilayer board (100) to plate a copper layer on the inner wall of the second hole position, thereby obtaining a second metallized hole (160).

5. The method for manufacturing a circuit of a back-drilled via circuit board according to claim 1, characterized in that: In the step S200, the aperture of the dry film opening is 12 mil larger than the aperture of the back-drilled hole (150).

6. The method for manufacturing a circuit of a back-drilled via circuit board according to claim 1, characterized in that: After step S700, the multilayer board (100) is further subjected to outer layer AOI, surface treatment, performance testing, edge milling, final inspection and packaging.

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