Etching method of thick copper printed circuit board and printed circuit board
By thinning the copper layer twice through etching and tinning, the problem of severe side corrosion of the pads of thick copper printed circuit boards was solved, and the qualified size of the pads and reliable welding were achieved.
Patent Information
- Application Number
- CN202510753018.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-05
- Publication Date
- 2025-09-05
AI Technical Summary
The existing technology suffers from severe undercutting of pads in thick copper scenarios, which results in smaller pad sizes, affects welding reliability, and increases processing difficulty.
A two-step etching method is used to first thin the copper layer by 50%-75%, then tin-plating and laser ablation are performed, and finally a second etching is performed to form a qualified pad.
The size problem of the pads of thick copper printed circuit boards is improved, so that the pads meet welding requirements and the processing difficulty is reduced.
Smart Images
Figure CN120603148A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of circuit boards, and in particular to an etching method for a thick copper printed circuit board and a printed circuit board. Background Art
[0002] Printed circuit boards (PCBs), also known as printed circuit boards (PCBs), are important electronic components that support and connect electronic components. Thick copper PCBs are widely used in power systems, automotive electronics, industrial control, aerospace, and other fields due to their high current carrying capacity, excellent heat dissipation, and mechanical strength.
[0003] With the growing demand for electric vehicles, AI servers and renewable energy, thick copper printed circuit boards will develop towards higher copper thickness. The outer layer etching in thick copper scenarios has always been one of the processing difficulties for printed circuit board manufacturers.
[0004] Existing techniques typically use a single etching process to produce pads. However, this single-etching process often results in significant undercutting of the pads in thick copper applications, which can even directly reduce the pad size and affect the reliability of subsequent soldering. Traditional processing methods add compensation during etching, but the compensation value needs to be adjusted constantly to accommodate processing fluctuations, increasing the processing difficulty. Therefore, ensuring that surface pads meet standard during the outer layer etching process in thick copper applications has become a challenge for printed circuit board manufacturers. Summary of the Invention
[0005] The main technical problem solved by this application is to provide a thick copper printed circuit board etching method and printed circuit board, etching out qualified thick copper pad size, so that the pads on the obtained printed circuit board meet welding requirements.
[0006] The present application provides a method for etching a thick copper printed circuit board, wherein the method comprises: providing a thick copper printed circuit board; performing a first etching on a copper layer in a first etching area of the thick copper printed circuit board; plating a tin layer on a surface of the thick copper printed circuit board; ablating the tin layer of the thick copper printed circuit board to expose the copper layer in a second etching area of the first etching area; and performing a second etching on the copper layer in the second etching area of the thick copper printed circuit board to obtain a printed circuit board having a solder pad.
[0007] Before the step of performing the first etching on the copper layer of the first etching area of the thick copper printed circuit board, the method further comprises: applying a dry film to the surface of the thick copper printed circuit board; exposing and developing the dry film on the surface of the thick copper printed circuit board so that the dry film at least covers the surface of the pad and exposes the first etching area of the thick copper printed circuit board; wherein the first etching area is arranged around the pad.
[0008] The step of performing a first etching on the copper layer of the first etching area of the thick copper printed circuit board includes: performing a first etching on the first etching area of the thick copper printed circuit board to thin the copper layer of the first etching area; wherein the etching amount of the first etching is 50%-75% of the total thickness of the copper layer.
[0009] The second etching region is smaller in area than the first etching region, and the second etching region is located at the center of the first etching region.
[0010] Among them, the step of ablating the tin layer of the thick copper printed circuit board to expose the second etching area of the first etching area includes: using a laser to ablate the tin layer in the central area of the first etching area to expose the central area of the first etching area.
[0011] Wherein, after the step of etching the copper layer in the second etching area of the thick copper printed circuit board for the second time, the method includes: performing a tin stripping process on the thick copper printed circuit board to remove the tin layer on the surface of the thick copper printed circuit board.
[0012] Wherein, after the step of etching the copper layer in the second etching area of the thick copper printed circuit board for the second time, the method further includes: removing the dry film on the surface of the thick copper printed circuit board to expose the pads on the surface of the printed circuit board.
[0013] Wherein, the step of performing a first etching on the copper layer of the first etching area of the thick copper printed circuit board comprises: performing a first etching on the copper layer of the first etching area of the thick copper printed circuit board using a first etching solution; the step of performing a second etching on the copper layer of the second etching area of the thick copper printed circuit board comprises: performing a second etching on the copper layer of the second etching area of the thick copper printed circuit board using a second etching solution; wherein, the concentration of the second etching solution is not lower than the initial concentration of the first etching solution.
[0014] The present application also provides a printed circuit board, wherein the printed circuit board is etched using the etching method for a thick copper printed circuit board described in any of the above embodiments; wherein a solder pad is formed on the surface of the printed circuit board, and the distance between the bottom of the solder pad and the top of the solder pad on the vertical projection plane does not exceed 50% of the size of the solder pad.
[0015] The beneficial effects of the present application are as follows: the copper layer is thinned by etching the outer copper layer once, the thickness of the copper layer is reduced to a certain value, and then the outer layer is tinned, and the tin in the central area of the area to be etched is ablated by laser processing, and then a second etching is performed, and finally a qualified thick copper pad size is etched, so that the pads on the obtained printed circuit board meet the welding requirements, thereby improving the surface pad size problem of the thick copper printed circuit board after etching. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.
[0017] Figure 1 A schematic flow chart of an embodiment of an etching method for a thick copper printed circuit board provided in this application;
[0018] Figure 2 A schematic structural diagram of a first specific embodiment of a thick copper printed circuit board provided in this application;
[0019] Figure 3 A schematic structural diagram of a second specific embodiment of a thick copper printed circuit board provided in this application;
[0020] Figure 4 A schematic structural diagram of a third specific embodiment of a thick copper printed circuit board provided in this application;
[0021] Figure 5 A schematic structural diagram of a fourth specific embodiment of a thick copper printed circuit board provided in this application;
[0022] Figure 6 A schematic structural diagram of a fifth specific embodiment of a thick copper printed circuit board provided in this application;
[0023] Figure 7 A schematic structural diagram of a sixth specific embodiment of a thick copper printed circuit board provided in this application;
[0024] Figure 8 This is a schematic diagram of the structure of a thick copper printed circuit board after etching in the prior art;
[0025] Figure 9 This is a schematic structural diagram of a specific embodiment of the printed circuit board provided in this application. DETAILED DESCRIPTION
[0026] The following describes the embodiments of the present application in detail with reference to the accompanying drawings.
[0027] In the following description, for the purpose of illustration and not limitation, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0028] The terms used in the examples of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms "a," "the," and "the" used in the examples of this application and the appended claims are also intended to include plural forms. Unless otherwise clearly indicated above, "a plurality" generally includes at least two, but does not exclude the inclusion of at least one.
[0029] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.
[0030] It should be understood that the terms "comprises," "comprising," or any other variations thereof as used herein are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.
[0031] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.
[0032] In addition, if the embodiments of the present invention include descriptions of "first," "second," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one of such features.
[0033] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in every place in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.
[0034] This application provides a method for etching a thick copper printed circuit board. Figure 1 , Figure 1 This is a flow chart of an embodiment of a method for etching a thick copper printed circuit board provided in this application.
[0035] like Figure 1 As shown, the etching methods for thick copper printed circuit boards include:
[0036] Step S11: providing a thick copper printed circuit board.
[0037] Thick copper printed circuit board refers to a printed circuit board with a thick copper layer on its surface. Figure 2 , Figure 2 This is a schematic structural diagram of the first specific embodiment of the thick copper printed circuit board provided by this application. Figure 2 As shown, a thick copper layer 10 is formed on the surface of the thick copper printed circuit board. The thick copper printed circuit board also includes blind holes connecting the inner layer copper layer, which is not limited here.
[0038] Step S12: performing a first etching on the copper layer of the first etching area of the thick copper printed circuit board.
[0039] The first etching area is the area to be etched. In this embodiment, the area to be etched is arranged around the pad. The copper layer is the outermost copper layer of the thick copper printed circuit board.
[0040] In a specific embodiment, this step also includes: pasting a dry film on the non-etched area of the thick copper printed circuit board. Specifically, it includes: pasting a dry film on the surface of the thick copper printed circuit board; exposing and developing the dry film on the surface of the thick copper printed circuit board to expose the first etched area of the thick copper printed circuit board. Specifically, after the dry film on the surface of the thick copper printed circuit board is exposed and developed, the dry film is at least covered on the surface of the pad of the thick copper printed circuit board. The dry film can also cover the circuit copper layer on the surface of the thick copper printed circuit board. In this embodiment, the pad includes the pattern copper layer left after the outer copper layer of the printed circuit board is etched, and the area where the pad is located is the non-etched area. For details, please refer to Figure 3 , Figure 3 This is a schematic structural diagram of the second specific embodiment of the thick copper printed circuit board provided by this application. Figure 3 As shown, the surface of the thick copper layer 10 of the thick copper printed circuit board is covered with a patterned dry film 20 . The patterned dry film 20 covers a portion of the surface of the thick copper layer 10 and exposes a first etching area 101 to be etched.
[0041] This step also includes: performing a first etching on the first etching area of the thick copper printed circuit board using a first etching solution. This step thins the surface copper layer of the thick copper printed circuit board in the first etching area by performing the first etching on the first etching area of the thick copper printed circuit board.
[0042] This step also includes controlling the amount of thinning of the thick copper, that is, the etching amount of the first etching. In a specific embodiment, the etching amount of the first etching is 50%-75% of the total thickness of the copper layer. The total thickness of the copper layer refers to the thickness of the thick copper layer of the outer layer of the thick copper printed circuit board, and the etching amount refers to the amount of thinning or the thickness of the outer thick copper layer. For details, please refer to Figure 4 , Figure 4 This is a schematic structural diagram of the third specific embodiment of the thick copper printed circuit board provided by this application. Figure 4 As shown, the thick copper layer 10 in the first etching region 101 is partially etched to reduce the thickness of the copper layer in the first etching region 101 .
[0043] Step S13: plating a tin layer on the surface of the thick copper printed circuit board.
[0044] Specifically, a tin layer is plated on the surface of the thick copper printed circuit board at least in the first etching area. In a specific embodiment, the thick copper printed circuit board is tinned throughout the board so that the tin layer covers at least the surface of the copper layer in the first etching area. Since the pad area of the thick copper printed circuit board is covered with a dry film, the electroplated tin layer covers the surface of the residual copper layer in the first etching area after the first etching. For details, please refer to Figure 5 , Figure 5 This is a schematic structural diagram of the fourth specific embodiment of the thick copper printed circuit board provided by this application. Figure 5As shown, a tin layer 30 is electroplated on the surface of the copper layer 10 in the first etched area 101 , so that the tin layer 30 covers the surface of the copper layer 10 in the first etched area 101 .
[0045] Step S14: performing ablation processing on the tin layer of the thick copper printed circuit board to expose the copper layer of the first etching area and the second etching area.
[0046] The second etching area is smaller than the first etching area and is a partial area of the first etching area. In a specific embodiment, the second etching area is located at the center of the first etching area to facilitate etching of the center of the first etching area and reduce the side etching effect of the etching solution on the pad. The tin layer after ablation is arranged to cover the periphery of the first etching area, exposing the center of the first etching area. For details, please refer to Figure 6 , Figure 6 This is a schematic structural diagram of the fifth specific embodiment of the thick copper printed circuit board provided by this application. Figure 6 As shown, the tin layer 30 covers a portion of the copper layer surface in the first etched area 101 and exposes the second etched area 102 .
[0047] This step specifically includes: using laser to ablate the tin layer in the central area of the first etching area. In other embodiments, the tin layer can also be etched by other processes, which are not limited here.
[0048] Step S15: performing a second etching on the copper layer of the second etching area of the thick copper printed circuit board to obtain a printed circuit board with solder pads.
[0049] The thickness of the pad is the same as the thickness of the outer thick copper layer of the thick copper printed circuit board, that is, the thickness of the pad is not thinned.
[0050] The copper layer in this step is the copper layer remaining after the first etching, which is specifically manifested as: the thickness of the copper layer in this step is less than the thickness of the copper layer in the first etching.
[0051] This step specifically includes: etching the second etching area of the thick copper printed circuit board using a second etching solution. The concentration of the second etching solution is not lower than the initial concentration of the first etching solution. In a preferred embodiment, the concentration of the second etching solution can be greater than the concentration of the first etching solution, so that the etching rate of the copper layer by the second etching solution is greater than the etching rate of the copper layer by the first etching solution, thereby making the side etching rate of the copper layer by the second etching solution greater than the side etching rate of the copper layer by the first etching solution, thereby reducing the distance between the bottom and the top of the copper layer. For details, please refer to Figure 7 , Figure 7 This is a schematic structural diagram of the sixth specific embodiment of the thick copper printed circuit board provided by this application. Figure 7As shown, the copper layer in the second etching area 102 is etched, and the tin layer and dry film on the surface of the thick copper printed circuit board are removed to obtain a soldering pad 11. There may be multiple soldering pads 11. The distance W between the bottom and top of the soldering pad 11 on the vertical projection plane does not exceed 50% of the thickness H of the soldering pad 11. The thickness refers to the thickness of the soldering pad 11 in a direction perpendicular to the projection plane. The soldering pad 11 also forms the outer copper layer of the thick copper printed circuit board.
[0052] After this step, the method further includes: performing a tin stripping process on the thick copper printed circuit board to remove the tin layer on the surface of the thick copper printed circuit board.
[0053] After this step, the process further includes removing the dry film on the surface of the thick copper printed circuit board to expose the copper layer on the surface of the printed circuit board to form solder pads. The dry film removal process may be performed after or simultaneously with the solder stripping process, which is not limited here.
[0054] To illustrate the improvements of the etching method for thick copper printed circuit boards in this application, please refer to Figure 8 , Figure 8 This is a schematic diagram of the structure of a thick copper printed circuit board after etching in the prior art. Figure 8 As shown, the pad 11 formed after a single etching of thick copper has a spacing W1 between the bottom and the top of the pad 11 that is larger than the spacing W between the bottom and the top of the pad 11 formed after two etchings in the present application. In the prior art, because the copper layer on the surface of the thick copper printed circuit board is only etched once, the spacing W1 between the bottom and the top of the pad 11 becomes larger. In order to form an independent pad 11 (that is, the copper layers of two adjacent pads or circuit copper layers are not connected), the size W2 of the top of the pad 11 will decrease with the etching process. As a result, the size W2 of the pad 11 obtained in the prior art is smaller than the size of the pad 11 obtained by the etching method of the present application.
[0055] This application thins the outer copper layer to a certain value through the first etching, then tin-plates the outer layer, burns the tin around the pad through laser processing, and then performs a second etching to finally etch out a qualified thick copper pad size, so that the pad on the surface of the resulting printed circuit board can meet the welding requirements.
[0056] It is understandable that in other embodiments, the outer copper layer may be etched a third time and a fourth time, that is, multiple etchings may be performed to etch out pads that meet the size, which is not limited here.
[0057] The present application also provides a printed circuit board, wherein the printed circuit board is etched using the etching method for a thick copper printed circuit board described in any of the above embodiments. Specifically, it includes providing a thick copper printed circuit board with a thick copper layer on the surface, and then etching the thick copper layer on the surface of the thick copper printed circuit board using the etching method described in any of the above embodiments to obtain a printed circuit board with a solder pad. For details, please refer to Figure 9 , Figure 9 This is a schematic diagram of the structure of a specific embodiment of the printed circuit board provided in this application. Figure 9 As shown, a plurality of pads 11 are formed on the surface of the printed circuit board. The spacing W between the bottom and top of pads 11, etched using the etching method described in the above embodiment, on a vertical projection plane does not exceed 50% of the thickness H of pads 11 along the vertical projection plane. In other words, the angle between the bottom and top of pads 11 is not less than 45 degrees, resulting in steeper sidewalls of pads 11.
[0058] The above are merely implementation methods of the present application and are not intended to limit the patent scope of the present application. Any equivalent structural or equivalent process transformations made using the contents of the present application specification and drawings, or simple reorganization of method steps, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.
Claims
1. A method for etching a thick copper printed circuit board, characterized in that: The etching method of the thick copper printed circuit board comprises: Providing a thick copper printed circuit board; Performing a first etching on the copper layer of the first etching area of the thick copper printed circuit board; Plating a tin layer on the surface of the thick copper printed circuit board; ablating the tin layer of the thick copper printed circuit board to expose the copper layer of the second etching area of the first etching area; The copper layer in the second etching area of the thick copper printed circuit board is etched a second time to obtain a printed circuit board with solder pads.
2. The etching method for thick copper printed circuit board according to claim 1, characterized in that: Before the step of etching the copper layer of the first etching area of the thick copper printed circuit board for the first time, the method includes: affixing a dry film on the surface of the thick copper printed circuit board; The dry film on the surface of the thick copper printed circuit board is exposed and developed so that the dry film at least covers the surface of the pad and exposes a first etching area of the thick copper printed circuit board; wherein the first etching area is arranged around the pad.
3. The etching method for thick copper printed circuit board according to claim 1, characterized in that: The step of performing a first etching on the copper layer of the first etching area of the thick copper printed circuit board comprises: A first etching is performed on the first etching area of the thick copper printed circuit board to thin the copper layer in the first etching area; wherein the etching amount of the first etching is 50%-75% of the total thickness of the copper layer.
4. The etching method for thick copper printed circuit board according to claim 1, characterized in that: The step of plating a tin layer on the surface of the thick copper printed circuit board comprises: The thick copper printed circuit board is entirely tinned so that the tin layer at least covers the surface of the copper layer in the first etching area.
5. The etching method for thick copper printed circuit board according to claim 4, characterized in that: The second etching region is smaller in area than the first etching region, and the second etching region is located at a center position of the first etching region.
6. The etching method for thick copper printed circuit board according to claim 5, characterized in that: The step of ablating the tin layer of the thick copper printed circuit board to expose the second etching area of the first etching area includes: The tin layer in the central area of the first etching area is ablated by using a laser to expose the central area of the first etching area.
7. The etching method for thick copper printed circuit board according to claim 6, characterized in that: After the step of etching the copper layer of the second etching area of the thick copper printed circuit board for the second time, the method includes: The thick copper printed circuit board is subjected to a tin stripping treatment to remove the tin layer on the surface of the thick copper printed circuit board.
8. The etching method for thick copper printed circuit board according to claim 2, characterized in that: After the step of etching the copper layer of the second etching area of the thick copper printed circuit board for the second time, the method further includes: The dry film on the surface of the thick copper printed circuit board is removed to expose the solder pads on the surface of the printed circuit board.
9. The etching method for thick copper printed circuit board according to claim 1, characterized in that: The step of performing a first etching on the copper layer of the first etching area of the thick copper printed circuit board comprises: Performing a first etching on the copper layer of the first etching area of the thick copper printed circuit board using a first etching solution; The step of etching the copper layer of the second etching area of the thick copper printed circuit board for the second time comprises: Etching the copper layer of the second etching area of the thick copper printed circuit board for a second time using a second etching solution; Wherein, the concentration of the second etching solution is not lower than the initial concentration of the first etching solution.
10. A printed circuit board, characterized in that: The printed circuit board is obtained by etching using the etching method for a thick copper printed circuit board according to any one of claims 1 to 9; A soldering pad is formed on the surface of the printed circuit board, and the distance between the bottom of the soldering pad and the top of the soldering pad on a vertical projection plane does not exceed 50% of the thickness of the soldering pad.