A thick copper circuit board with a stepped circuit and a manufacturing method thereof

Abstract

The present invention discloses a manufacturing method of a thick copper circuit board with stepped circuits. The method includes: providing a thick copper layer to be manufactured; performing a first etching process on the thick copper layer to etch a plurality of blind vias on one side of the thick copper area; performing a second etching process on the thick copper layer to etch a plurality of grooves on the back side at the positions of the blind vias in the thick copper area, with the grooves communicating with and corresponding to the blind vias one by one; performing a third etching process on the thick copper layer to reduce the copper thickness of the thin copper area of the thick copper layer; attaching a cover film to the flat surface of the thick copper layer and performing a fourth etching process on the thick copper layer to form a thick copper layer with stepped circuits; attaching a cover film to the stepped surface of the thick copper layer with stepped circuits to form a thick copper circuit board with stepped circuits. In the technical solution of the present invention, the manufacturing method of the thick copper circuit board with stepped circuits provided by the present invention effectively reduces the processing difficulty by adopting four conventional etching processes, without using a specially set punching die, thus saving production costs.

Description

Technical Field

[0001] The present invention relates to the field of circuit boards, and particularly to a manufacturing method of a thick copper circuit board with stepped circuits and a thick copper circuit board with stepped circuits. Background Art

[0002] For a type of electrical device that needs to carry a large current, a thick copper flexible circuit board is required. A thick copper circuit board generally refers to a circuit board with a copper thickness greater than or equal to 75 μm. Due to the relatively thick copper thickness, there are often problems with poor etching during the manufacturing process of thick copper circuit boards.

[0003] A thick copper circuit board generally functions as a carrier or a connector. When functioning as a connector, a special printed circuit board design with thick copper hollowing is generally adopted, that is, the spaces between adjacent circuits are in a relatively independent state, and the appearance shows a hollowed-out effect.

[0004] For a thick copper hollowed-out special printed circuit board that requires a strong plug-in effect, stepped circuits are generally designed, that is, the same circuit includes both a region with a relatively thick copper thickness and a region with a relatively thin copper thickness.

[0005] For a thick copper hollowed-out special printed circuit board with stepped circuits, the circuits are generally formed by punching. Punching can be formed in one step and has the characteristics of high efficiency and precision.

[0006] However, the copper thickness of the circuits that can generally be produced by punching is 75 μm. Even with a specially set punching die, the maximum thickness that can generally be produced is only 175 μm. For a circuit copper thickness greater than 175 μm, problems such as circuit deformation, continuous punching failure, punching die breakage, and excessive punching burrs will occur during punching. Moreover, for a thick copper plate with stepped circuits, problems such as bending and curling at the stepped positions may occur during punching.

[0007] Therefore, for the manufacturing of a thick copper hollowed-out special printed circuit board with stepped circuits and a circuit copper thickness greater than 175 μm, a new manufacturing method needs to be explored. Summary of the Invention

[0008] The main object of the present invention is to propose a thick copper circuit board with stepped circuits and its manufacturing method, aiming to solve the problems such as circuit deformation, continuous punching failure, punching die breakage, and excessive punching burrs that easily occur when using punching for the existing thick copper hollowed-out special printed circuit board with stepped circuits.

[0009] To achieve the above object, a manufacturing method of a thick copper circuit board with stepped circuits proposed by the present invention includes:

[0010] Providing a thick copper layer to be manufactured, the thick copper layer including a thin copper region and a thick copper region;

[0011] Perform the first etching process on the thick copper layer to etch a plurality of blind holes on one side of the thick copper region;

[0012] Perform the second etching process on the thick copper layer to etch a plurality of grooves on the back side of the blind holes in the thick copper region, and the grooves communicate with and correspond to the blind holes one by one;

[0013] Perform the third etching process on the thick copper layer to reduce the copper in the thin copper region of the thick copper layer;

[0014] Attach a cover film to the flat surface of the thick copper layer and perform the fourth etching process on the thick copper layer to form a thick copper layer with a stepped circuit;

[0015] Attach a cover film to the stepped surface of the thick copper layer with the stepped circuit to form a thick copper circuit board with a stepped circuit.

[0016] Furthermore, the thickness of the thick copper layer is greater than or equal to 175 μm.

[0017] Furthermore, the depth of the blind holes is 1 / 3 - 1 / 4 of the thickness of the thick copper layer, and the sum of the depth of the grooves and the depth of the blind holes is equal to the thickness of the thick copper layer.

[0018] Furthermore, the first etching process, the second etching process, the third etching process, and the fourth etching process are all etching processes that use a photosensitive wet film as a photoresist film layer for pattern transfer processing.

[0019] Furthermore, the step of performing the first etching process on the thick copper layer to etch a plurality of blind holes on one side of the thick copper region includes:

[0020] Fabricate a first photosensitive wet film layer on both sides of the thick copper layer;

[0021] Perform exposure and development process on the thick copper layer with the first photosensitive wet film layer fabricated thereon in sequence, wherein the developed pattern in the development process includes a first opening pattern in the thick copper region;

[0022] Perform the first etching process on the developed thick copper layer to etch a plurality of blind holes at the first opening pattern.

[0023] Furthermore, the step of performing the second etching process on the thick copper layer to etch a plurality of grooves on the back side of the blind holes in the thick copper region, and the grooves communicate with and correspond to the blind holes one by one includes:

[0024] Fabricate a second photosensitive wet film layer on both sides of the thick copper layer, and fill the blind holes with the second photosensitive wet film;

[0025] The thick copper layer for making the second photosensitive wet film layer is sequentially subjected to exposure and development process treatments. Among them, the developed pattern in the development process includes the second opening pattern in the thick copper area;

[0026] The developed thick copper layer is subjected to a second etching process treatment, and a plurality of grooves are etched at the second opening pattern, and the plurality of grooves communicate with and correspond to the plurality of blind holes one by one.

[0027] Further, the step of subjecting the thick copper layer to a third etching process treatment and reducing the copper in the thin copper area of the thick copper layer includes:

[0028] The grooves are filled with a third photosensitive wet film;

[0029] The third photosensitive wet film layers are made on both sides of the thick copper layer;

[0030] The thick copper layer for making the third photosensitive wet film layer is sequentially subjected to exposure and development process treatments. Among them, the developed pattern in the development process includes the circuit in the entire thin copper area;

[0031] The developed thick copper layer is subjected to a third etching process treatment to reduce the copper in the thin copper area of the thick copper layer.

[0032] Further, the step of covering the thick copper layer with a cover film on the flat surface and subjecting the thick copper layer to a fourth etching process treatment to form a thick copper layer with a stepped circuit includes:

[0033] Cover the thick copper layer with a cover film on the flat surface;

[0034] The fourth photosensitive wet film layers are made on both sides of the thick copper layer after covering with the cover film;

[0035] The thick copper layer for making the fourth photosensitive wet film layer is sequentially subjected to exposure and development process treatments. Among them, the developed pattern in the development process includes the stepped circuit;

[0036] The developed thick copper layer is subjected to a fourth etching process treatment to form a thick copper layer with a stepped circuit.

[0037] Further, the cover film includes a film layer and an adhesive layer, and the ratio of the thickness of the adhesive layer to the thickness of the thick copper layer is 0.8:1.

[0038] To achieve the above object, a thick copper circuit board with a stepped circuit proposed by the present invention is made by the above-mentioned manufacturing method.

[0039] In the technical solution of the present invention, the manufacturing method of the thick copper circuit board with stepped circuits provided by the present invention effectively reduces the processing difficulty through four conventional etching processes, and does not require a specially set punching die, saving production costs. Description of the Drawings

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0041] Figure 1 Schematic process flow diagram of a manufacturing method of a thick copper circuit board with stepped circuits according to the present invention;

[0042] Figure 2 Schematic plan view of an embodiment of a thick copper circuit board with stepped circuits according to the present invention;

[0043] Figure 3 In the present invention Figure 1 Partial process flow diagram of step S20;

[0044] FIG. 4 is a schematic structural diagram of the step decomposition of the present invention (including Figure 3 ); Figures 4-A to 4-D );

[0045] Figure 5 In the present invention Figure 1 Partial process flow diagram of step S30;

[0046] FIG. 6 is a schematic structural diagram of the step decomposition of the present invention (including Figure 5 ); Figures 6-A to 6-C );

[0047] Figure 7 In the present invention Figure 1 Partial process flow diagram of step S40;

[0048] FIG. 8 is a schematic structural diagram of the step decomposition of the present invention (including Figure 7 ); Figures 8-A to 8-D );

[0049] Figure 9 In the present invention Figure 1 Partial process flow diagram of step S50.

[0050] Explanation of the reference numerals in the drawings:

[0051] Label Name Label Name 100 Thick copper circuit board with stepped circuit 160 Cover film 100A Thick copper area 120 First photosensitive wet film layer 100B Thin copper area 130 Second photosensitive wet film layer 110 Stepped circuit 140 Third photosensitive wet film layer 101 Blind hole 150 Fourth photosensitive wet film layer 102 Tank / /

[0052] The realization, functional features and advantages of the present invention will be further described in conjunction with embodiments with reference to the accompanying drawings. Detailed implementation manners

[0053] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0054] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0055] In addition, the descriptions such as "first" and "second" in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0056] In the present invention, unless otherwise clearly defined and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0057] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0058] Please refer to Figure 1 and Figure 2 , Figure 1 is a schematic process flow diagram of a method for manufacturing a thick copper circuit board with stepped lines according to the present invention; Figure 2 is a schematic plan view of an embodiment of a thick copper circuit board with stepped lines according to the present invention.

[0059] As Figure 2 shown, the thick copper circuit board 100 with stepped lines of this embodiment is obtained by the Figure 1 manufacturing method. The thick copper circuit board 100 with stepped lines is a circuit board composed of multiple stepped thick copper lines 110 with the same structure. Each stepped thick copper line includes a thick copper area A and a thin copper area B, and covering films 160 are provided on both sides of the thin copper area B of the stepped thick copper lines 110 with the same structure. The thick copper circuit board 100 with stepped lines in this embodiment can be rectangular or fan-shaped.

[0060] Please refer to Figures 1 to 9 together. The steps of the manufacturing method of a thick copper circuit board with stepped lines according to the present invention specifically include S10 to S60.

[0061] The following is an explanation of the specific implementation manner of step S10:

[0062] Step S10: Provide a thick copper layer to be manufactured, where the thick copper layer includes a thin copper area and a thick copper area.

[0063] In this embodiment, the thick copper layer 100 to be manufactured is a thick copper plate with only thick copper, which is an ordinary thick copper plate without epoxy resin as a support. Among them, the thickness of the thick copper layer 110 is greater than or equal to 175 μm, that is, the copper thickness of the thick copper layer 100 is greater than or equal to 175 μm.

[0064] Among them, the thick copper layer 100 including the thin copper area A and the thick copper area B does not mean that the thick copper plate to be manufactured has a distinction between the thin copper area and the thick copper area, but rather the thin copper area and the thick copper area are provided according to the distribution of the circuit pattern design. The thick copper layer is a thick copper plate with a uniform thickness and a thickness greater than or equal to 175 μm. The distinction between the thin copper area and the thick copper area of the thick copper layer in this embodiment is also for distinguishing subsequent manufacturing, without special limitations.

[0065] The following is an explanation of the specific implementation manner of step S20:

[0066] Step S20: Perform a first etching process on the thick copper layer to etch out a plurality of blind holes on one side of the thick copper area.

[0067] As Figure 3 shown, step S20 specifically includes:

[0068] Step S201: Manufacture a first photosensitive wet film layer on both sides of the thick copper layer.

[0069] Specifically referring to FIG. 4, a first photosensitive wet film layer 120 is made on both sides (i.e., including the upper side and the lower side) of the thick copper layer 100. In practical applications, a photosensitive wet film is coated or screen-printed on both sides of the thick copper layer so that a first photosensitive wet film layer is formed on both sides of the thick copper layer. The photosensitive wet film is a blue viscous liquid synthesized from a photosensitive resin, in which a photosensitizer, a colorant, a filler, and a solvent are added. The concave pits and scratched parts on the substrate have good contact with the wet film, and the wet film is mainly bonded to the substrate through chemical bonds, so that there is good adhesion between the photosensitive wet film and the substrate copper foil. Using screen printing can obtain good coverage, providing processing conditions for high-precision fine circuit boards.

[0070] The thick copper layer with the photosensitive wet film screen-printed needs to be pre-baked, mainly to evaporate the solvent in the photosensitive wet film, thereby forming a photosensitive wet film layer. Making the first photosensitive wet film layer belongs to conventional existing technology and will not be elaborated here.

[0071] Step S202: The thick copper layer on which the first photosensitive wet film layer is made is sequentially subjected to exposure and development process treatments. Among them, the developed pattern in the development process includes a first opening pattern in the thick copper area.

[0072] The thick copper layer 100 with the first photosensitive wet film layer 120 attached to both sides is sequentially subjected to exposure and development process treatments. Among them, the exposure process is a photopolymerization reaction process in which monomer molecules in the photosensitive wet film without pattern blockage generate after absorbing light energy under the action of ultraviolet rays using a film with a circuit pattern. The development process is a process of removing the unexposed part of the photosensitive wet film layer to obtain the required pattern. Among them, the exposure process and the development process belong to conventional existing technology and will not be elaborated here.

[0073] In this embodiment, the developed pattern in the development process includes a first opening pattern in the thick copper area. Referring to FIG. 4, the first opening pattern after development is a plurality of round holes in the thick copper area A.

[0074] Step S203: The developed thick copper layer is subjected to a first etching process treatment to etch a plurality of blind holes at the first opening pattern.

[0075] The developed thick copper layer 100 is subjected to a first etching process treatment (specifically including etching and film removal treatment) to finally obtain the circuit pattern we need. In this embodiment, a plurality of blind holes are etched at the first opening pattern. Since the thick copper in the thick copper layer is relatively thick, the depth of the blind hole 101 is 1 / 3 - 1 / 4 of the thickness of the thick copper layer.

[0076] When etching different copper foil thicknesses, different etching speeds, etching solution temperatures, and etching solution concentrations need to be used in cooperation. Adopting conventional existing technology, it will not be elaborated here.

[0077] The following is an explanation of the specific implementation of step S30:

[0078] Step S30: Perform a second etching process on the thick copper layer to etch out a plurality of grooves on the back side at the blind holes in the thick copper area, and the grooves communicate with and correspond to the blind holes one by one.

[0079] As Figure 5 shown, step S30 specifically includes:

[0080] Step S301: Fabricate a second photosensitive wet film layer 130 on both sides of the thick copper layer, and fill the second photosensitive wet film 130 at the blind holes 101.

[0081] Specifically referring to FIG. 6, step S301 is basically the same as step S201 and will not be elaborated here. The difference is that the blind holes after the first etching process also need to be filled with the second photosensitive wet film.

[0082] Step S302: Perform exposure and development process on the thick copper layer with the second photosensitive wet film layer fabricated thereon. Among them, the developed pattern in the development process includes a second opening pattern in the thick copper area.

[0083] Step S302 is basically the same as step S202 and will not be elaborated here. The difference is that the developed pattern in the development process includes a second opening pattern in the thick copper area, and the second opening pattern in the thick copper area and the first opening pattern in the thick copper area are on different sides of the thick copper layer, that is, the second opening pattern in the thick copper area is on the corresponding side of the first opening pattern in the thick copper area.

[0084] Step S303: Perform a second etching process on the developed thick copper layer to etch out a plurality of grooves at the second opening pattern, and the plurality of grooves communicate with and correspond to the plurality of blind holes one by one.

[0085] Step S303 is basically the same as step S203 and will not be elaborated here. The difference is that a plurality of grooves 102 are etched at the second opening pattern, the plurality of grooves 102 communicate with and correspond to the plurality of blind holes 101 one by one, the number of the grooves 102 is the same as the number of the blind holes 101, and each etched groove 102 communicates with each blind hole 101, so that each blind hole becomes a through hole, and each blind hole is prepared for subsequent third etching to fill the photosensitive wet film in the groove for ventilation. Among them, the sum of the depth of the groove and the depth of the blind hole is equal to the thickness of the thick copper layer. Since the depth of the blind hole is 1 / 3 - 1 / 4 of the thickness of the thick copper layer, therefore, the depth of the groove is 2 / 3 - 3 / 4 of the thickness of the thick copper layer.

[0086] The following is an explanation of the specific implementation of step S40:

[0087] Step S40: Perform a third etching process on the thick copper layer to reduce the copper in the thin copper area of the thick copper layer.

[0088] As Figure 7 shown, step S40 specifically includes:

[0089] Step S401: Fill the groove with the third photosensitive wet film.

[0090] Specifically referring to FIG. 8, first fill the groove 102 with the third photosensitive wet film. In practical applications, due to the relatively deep depth of the groove 102, generally, the method of screen printing → standing → screen printing → standing → screen printing is adopted and repeated 3 - 4 times. First, perform pre-baking so that the third photosensitive wet film in the groove adheres tightly to the copper wall of the thick copper layer and bonds together.

[0091] Step S402: Fabricate the third photosensitive wet film layer on both sides of the thick copper layer.

[0092] Step S402 is basically the same as step S201 and will not be elaborated here. The difference is that screen print or coat the third photosensitive wet film on both sides of the thick copper layer filled with the third photosensitive wet film in the groove 102 to form the third photosensitive wet film layer 140, and perform a second pre-baking; among them, the photosensitive wet film in the groove 102 may be baked to complete curing (baked dead), but it does not affect the processing because there is no need to etch the pattern at this position of the groove in the finished circuit board, and even if it is baked to complete curing, it will not affect the processing.

[0093] Step S403: Perform exposure and development process on the thick copper layer fabricated with the third photosensitive wet film layer in sequence, where the developed pattern in the development process includes the circuits in the entire thin copper area.

[0094] Step S403 is basically the same as step S202 and will not be elaborated here. The difference is that the developed pattern in the development process includes the circuits in the entire thin copper area and is located in the thin copper area on one side of the groove. Among them, the non-developed pattern on this side of the groove is the thick copper area and is located directly above the groove. The width of the non-developed pattern is smaller than the width of the groove, that is, the projected area of the non-developed pattern is smaller than the projected area of the groove. The other side of the groove is all non-developed pattern, which is the subsequent flat surface.

[0095] Step S404: Perform a third etching process on the developed thick copper layer to reduce the copper in the thin copper area of the thick copper layer.

[0096] Step S404 is basically the same as step S203, so it will not be elaborated here. The difference is that in the third etching process, copper reduction is performed on the entire thin copper area of the thick copper layer, while the thick copper area is not reduced, so that a stepped surface in a stepped shape is formed between the thin copper area and the thick copper area, making a preliminary preparation for the subsequent hollow stepped thick copper circuit board.

[0097] The following is an explanation of the specific implementation manner of step S50:

[0098] Step S50: Attach a cover film to the flat surface of the thick copper layer, and perform a fourth etching process on the thick copper layer to form a thick copper layer with stepped circuits.

[0099] As Figure 9 shown, step S50 specifically includes:

[0100] Step S501: Attach a cover film to the flat surface of the thick copper layer.

[0101] According to the graphic requirements of the cover film 160, attach the cover film 160 to the flat surface of the thick copper layer. The cover film 160 plays a role of fixing and supporting, preventing the independent circuits from scattering during subsequent etching and hollowing.

[0102] Step S502: Make the fourth photosensitive wet film layer on both sides of the thick copper layer after attaching the cover film.

[0103] Step S502 is basically the same as step S201, so it will not be elaborated here. The difference is that silk screen printing or coating of the fourth photosensitive wet film is performed on both sides of the thick copper layer after attaching the cover film to form the fourth photosensitive wet film layer 150. Among them, the fourth photosensitive wet film layer 150 is not made on the cover film 160. The thickness of the fourth photosensitive wet film layer 150 is greater than the thickness of the cover film 160, and the sides of the cover film 160 are sealed.

[0104] Step S503: Perform exposure and development process treatments on the thick copper layer with the fourth photosensitive wet film layer made, where the development pattern in the development process includes the stepped circuits.

[0105] Step S503 is basically the same as step S202, so it will not be elaborated here. The difference is that the development pattern in the development process includes the complete stepped circuit pattern, including the thick copper area and the thin copper area.

[0106] Step S504: Perform a fourth etching process on the developed thick copper layer to form a thick copper layer with stepped circuits, and the thick copper layer includes a thick copper area 100A and a thin copper area 100B.

[0107] Step S504 is basically the same as step S203 and will not be elaborated here. The difference is that the developed thick copper layer is subjected to a fourth etching process to form a thick copper layer with stepped circuits, and this thick copper layer is about to become a circuit board composed of multiple thick copper circuits 110 with the same stepped thickness.

[0108] The following is an explanation of the specific implementation of step S60:

[0109] Step S60: Stick a cover film on the stepped surface of the thick copper layer of the stepped circuit to form a thick copper circuit board with stepped circuits.

[0110] Specifically, stick a cover film 160 on the stepped surface of the thick copper layer of the stepped circuit to form a thick copper circuit board with stepped circuits. Among them, the cover films 160 on both sides of the thick copper layer are made of the same material. The cover film 160 is located in the thin copper area of the thick copper layer, and the thick copper area of the thick copper layer is exposed outside the cover film.

[0111] The cover film 160 in this embodiment includes a film layer and an adhesive layer. The ratio of the thickness of the adhesive layer to the thickness of the thick copper layer is 0.8:1, so that the cover film can be firmly adhered to the thick copper plate. Among them, the adhesive layer is located between the film layer and the thick copper layer.

[0112] In this embodiment, the first etching process, the second etching process, the third etching process, and the fourth etching process are all etching processes for pattern transfer processing using a photosensitive wet film as a photoresist film layer. Among them, the first etching process, the second etching process, the third etching process, and the fourth etching process are only for distinguishing the number of times, which are set according to actual needs and all adopt conventional existing technologies and will not be elaborated here. Similarly, the material compositions of the first photosensitive wet film layer 120, the second photosensitive wet film layer 130, the third photosensitive wet film layer 140, and the fourth photosensitive wet film layer 150 are the same and there are no special limitations.

[0113] In this embodiment, through the coordinated processing of four etching processes, problems such as circuit deformation, incomplete punching, broken punching tools, and excessive punching burrs generated by mechanical punching are avoided; the photosensitive wet film is used throughout the process to coat and make patterns (instead of using a photosensitive dry film). On the one hand, the flow and filling characteristics of the photosensitive wet film are utilized to achieve the filling of the circuit and pattern transfer, providing an effective photosensitive layer basis for the etching process. On the other hand, while ensuring the processing accuracy, the processing cost is effectively reduced; in addition, by adopting the manufacturing method of first making the circuits in the thick copper area and then making the circuits in the thin copper area, over-etching at the combination position of the thick copper area circuit and the thin copper area circuit is avoided, effectively improving the reliability of the circuit.

[0114] In summary, in the technical solution of the present invention, the method for manufacturing a thick copper circuit board with a stepped circuit provided by the present invention effectively reduces the processing difficulty by adopting four conventional etching processes, and does not require a specially set punching die, thus saving production costs.

[0115] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made by using the content of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields shall be included in the patent protection scope of the present invention.

Claims

1. A manufacturing method of a thick copper circuit board with a stepped circuit, characterized in that, The manufacturing method includes: Providing a thick copper layer to be manufactured, where the thick copper layer includes a thin copper area and a thick copper area; Performing a first etching process on the thick copper layer to etch a plurality of blind vias on one side of the thick copper area; Performing a second etching process on the thick copper layer to etch a plurality of grooves on the back side at the positions of the blind vias in the thick copper area, where the grooves communicate with and correspond to the blind vias one by one; Performing a third etching process on the thick copper layer to reduce the copper in the thin copper area of the thick copper layer; Applying a cover film on the flat surface of the thick copper layer and performing a fourth etching process on the thick copper layer to form a thick copper layer with stepped circuits; Applying a cover film on the stepped surface of the thick copper layer with stepped circuits to form a thick copper circuit board with stepped circuits.

2. The manufacturing method according to claim 1, characterized in that, The thickness of the thick copper layer is greater than or equal to 175 μm.

3. The manufacturing method according to claim 2, characterized in that, The depth of the blind vias is 1 / 3 - 1 / 4 of the thickness of the thick copper layer, and the sum of the depth of the grooves and the depth of the blind vias is equal to the thickness of the thick copper layer.

4. The manufacturing method according to claim 3, wherein The first etching process, the second etching process, the third etching process, and the fourth etching process are all etching processes for pattern transfer processing using a photosensitive wet film as a photoresist film layer.

5. The manufacturing method according to claim 4, characterized in that, The step of performing a first etching process on the thick copper layer to etch a plurality of blind vias on one side of the thick copper area includes: Fabricating a first photosensitive wet film layer on both sides of the thick copper layer; Successively performing an exposure process and a development process on the thick copper layer with the first photosensitive wet film layer fabricated thereon, where the development pattern in the development process includes a first opening pattern in the thick copper area; Performing a first etching process on the developed thick copper layer to etch a plurality of blind vias at the first opening pattern.

6. The manufacturing method according to claim 5, wherein, The step of performing a second etching process on the thick copper layer to etch a plurality of grooves on the back side at the positions of the blind vias in the thick copper area, where the grooves communicate with and correspond to the blind vias one by one, includes: Fabricating a second photosensitive wet film layer on both sides of the thick copper layer, and filling the blind vias with the second photosensitive wet film layer; Successively performing an exposure process and a development process on the thick copper layer with the second photosensitive wet film layer fabricated thereon, where the development pattern in the development process includes a second opening pattern in the thick copper area; Performing a second etching process on the developed thick copper layer to etch a plurality of grooves at the second opening pattern, and the plurality of grooves communicate with and correspond to the plurality of blind vias one by one.

7. The manufacturing method according to claim 6, wherein The step of performing a third etching process on the thick copper layer to reduce the copper in the thin copper area of the thick copper layer includes: Filling the grooves with a third photosensitive wet film; Fabricating a third photosensitive wet film layer on both sides of the thick copper layer; Successively performing an exposure process and a development process on the thick copper layer with the third photosensitive wet film layer fabricated thereon, where the development pattern in the development process includes the circuit of the entire thin copper area; Performing a third etching process on the developed thick copper layer to reduce the copper in the thin copper area of the thick copper layer.

8. The manufacturing method according to claim 3, characterized in that, The step of applying a cover film on the flat surface of the thick copper layer and performing a fourth etching process on the thick copper layer to form a thick copper layer with stepped circuits includes: Applying a cover film on the flat surface of the thick copper layer; Fabricate a fourth photosensitive wet film layer on both sides of the thick copper layer after pasting the cover film; Perform exposure and development process treatments on the thick copper layer where the fourth photosensitive wet film layer is fabricated. Among them, the developed pattern in the development process includes the stepped circuit; Perform a fourth etching process treatment on the developed thick copper layer to form a thick copper layer with a stepped circuit.

9. The manufacturing method according to claim 1, wherein, The cover film includes a film layer and an adhesive layer, and the ratio of the thickness of the adhesive layer to the thickness of the thick copper layer is 0.8:

1.

10. A thick copper circuit board with a stepped circuit, characterized in that, The thick copper circuit board is made by the manufacturing method according to any one of claims 1-9.

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