Electroplating method for stepped thick copper circuit board

Abstract

Disclosed in the present invention is an electroplating method for a stepped thick copper circuit board, comprising the following steps: performing full-board electroplating on an outer-layer copper surface of a circuit board, so that the copper thickness meets the copper thickness requirements of a thin copper area; developing a stepped circuit pattern by means of roller film lamination, exposure, and development, using a protective film to cover a circuit area that does not need to be thickened, and exposing a thick copper circuit and a hole; electroplating the exposed thick copper circuit and hole, so that the copper thickness meets the copper thickness requirements of a thick copper area, thus obtaining a stepped circuit board; removing the protective film, obtaining a stepped circuit after etching treatment, and then removing tin; and successively carrying out processes of solder mask preparation, surface treatment, and forming on the stepped circuit board to obtain a stepped thick copper circuit board. According to the electroplating method for the stepped thick copper circuit board in the present invention, by first forming the thin copper area and then forming the thick copper area, the precision requirements of the thin copper area can be met, higher copper thickness uniformity and copper thickness precision can be achieved, cost is low, and high economic benefits are achieved.

Description

Electroplating method for stepped thick copper circuit board Technical Field

[0001] The present invention relates to the technical field of printed circuit boards, and in particular to an electroplating method for a stepped thick copper circuit board. Background Art

[0002] Thick copper circuit boards are used as automotive electronic components, especially in high-power and high-voltage parts such as engine power supply parts and automobile central electrical power supply parts. They are required to have high reliability characteristics such as heat aging resistance and high and low temperature cycle resistance.

[0003] In addition to ensuring the heat dissipation reliability of the product, it is also necessary to ensure product performance and control product costs. Different parts of the circuit board have different line thickness requirements, and thick copper step circuit boards have appeared in circuit board production; thick copper step circuit boards refer to multiple lines on the same side of the board with different copper thicknesses, one part of which is thin copper line and the other part is thick copper line.

[0004] In the existing circuit board manufacturing process, the manufacturing technology of thick copper stepped circuit boards has the following technical difficulties: (1) The difference between the thickness of the copper lines on the board surface is large, which easily leads to quality problems such as film clamping during electroplating; (2) In the circuit pattern transfer process, dry film is used as the anti-etching layer. Due to the unevenness of the circuit surface and the presence of line corners, there are gaps in the dry film after rolling, resulting in quality problems such as line gaps and unclean etching after etching; (3) The pool effect of thick copper lines affects the uniformity of line etching; (4) The manufacturing process is complicated and the cost is too high. Therefore, we propose a plating method for stepped thick copper circuit boards.

[0005] Summary of the Invention

[0006] The main purpose of the present invention is to provide an electroplating method for a stepped thick copper circuit board, which can effectively solve the problems in the background technology.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for electroplating a stepped thick copper circuit board comprises the following steps:

[0009] S1. Electroplate the entire outer copper surface of the circuit board so that the copper thickness meets the copper thickness requirements of the thin copper area;

[0010] S2, through the film rolling, exposure, and development processes, a step circuit pattern is developed, the area where the circuit does not need to be thickened is covered with a protective film, and the thick copper circuit and hole are exposed;

[0011] S3, electroplating the exposed thick copper lines and holes to make the copper thickness meet the copper thickness requirements of the thick copper area, thereby obtaining a stepped circuit board;

[0012] S4, remove the protective film, obtain a stepped circuit through etching, and then remove the tin;

[0013] S5. Performing solder mask, surface treatment and forming steps on the stepped circuit board in sequence to obtain a stepped thick copper circuit board.

[0014] Preferably, the copper thickness of the thin copper area is 12-22 μm.

[0015] Preferably, the difference in copper thickness between the thin copper region and the thick copper region is greater than 20 μm.

[0016] Preferably, in S1, the electroplating parameters are: current density 8-22ASF, and electroplating time 36-120min.

[0017] Preferably, in said S2, the film rolling process uses two or more layers of 2mil protective film, and the parameters of the rolling plate are: the rolling plate pressure is 4±1kg / cm 2 , hot roller temperature 100±10℃, roller plate speed 2.6±0.3m / min, plate outlet temperature 42-58℃.

[0018] Preferably, in S2, the protective film is a PVC electroplated blue film.

[0019] Preferably, in S2, covering the area where the circuit does not need to be thickened with a dry film and exposing the thick copper circuit and the hole specifically includes:

[0020] S201: Pressing a protective film on the stepped circuit diagram;

[0021] S202: performing laser cutting on the protective film at the boundary between the thin copper circuit pattern and the thick copper circuit pattern;

[0022] S203: removing the protective film on the surface of the thick copper circuit pattern.

[0023] Preferably, in S3, the electroplating parameters are: current density 16-42ASF, and electroplating time 60-320min.

[0024] Preferably, in said S4, the production board is etched in a vacuum environment using an alkaline etching solution, and the etching parameters are: etching pressure 2.5 kg / cm 2 , etching speed 6-9m / min.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention provides a method for electroplating a stepped thick copper circuit board. By electroplating the entire outer copper surface of the circuit board, the copper thickness reaches the copper thickness requirement of the thin copper area. The thin copper area is first made and then the thick copper area is made. This method can not only meet the precision requirements of the thin copper area, but also achieve higher copper thickness uniformity and copper thickness accuracy. The process is simple and the reliability is good.

[0027] 2. The present invention provides an electroplating method for a stepped thick copper circuit board, which effectively solves the quality problem of the film by using two or more layers of 2mil dry film in the film rolling process. At the same time, a protective film is used to cover the area where the circuit does not need to be thickened, thereby preventing the thin copper circuit pattern from being electroplated when the copper layer is electroplated on the surface of the thick copper circuit pattern. At the same time, the protective film is laser cut at the boundary between the thin copper circuit pattern and the thick copper circuit pattern, so that the junction between the thin copper circuit pattern and the thick copper circuit pattern can be smooth and neat.

[0028] 3. The electroplating method of a stepped thick copper circuit board provided by the present invention effectively solves the quality problems such as circuit gaps and unclean etching caused by the inability to make the anti-corrosion layer and the circuit closely attached when using a dry film process by etching the surface of the stepped circuit board, and then going through the steps of making a solder mask layer, surface treatment and molding. The entire production process is compatible with traditional circuit board technology, has low cost and high economic benefits. DETAILED DESCRIPTION

[0029] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0030] In the description of the present invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," "the other end," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "provided with," "connected," etc., should be understood in a broad sense. For example, "connected" may refer to a fixed connection, a detachable connection, or an integral connection; it may refer to a mechanical connection or an electrical connection; it may refer to a direct connection or an indirect connection through an intermediate medium; it may refer to internal communication between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0032] Example 1

[0033] A method for electroplating a stepped thick copper circuit board comprises the following steps:

[0034] S1. Electroplating the entire outer copper surface of the circuit board to ensure that the copper thickness meets the copper thickness requirements of the thin copper area. The electroplating parameters are: current density 8-22ASF, electroplating time 36-120min;

[0035] S2. Through the lamination, exposure and development process, the ladder circuit diagram is developed. The area where the circuit does not need to be thickened is covered with a protective film. The protective film is a PVC electroplated blue film, and the thick copper circuit and hole are exposed. The lamination process uses two or more layers of 2mil protective film. The lamination parameters are: lamination pressure 4±1kg / cm 2 , hot roller temperature 100±10℃, roller plate speed 2.6±0.3m / min, plate outlet temperature 42-58℃;

[0036] The steps of covering the areas where thickened circuits are not required with dry film and exposing the thick copper circuits and holes include:

[0037] S201: Pressing a protective film on the stepped circuit diagram;

[0038] S202: performing laser cutting on the protective film at the boundary between the thin copper circuit pattern and the thick copper circuit pattern;

[0039] S203: removing the protective film on the surface of the thick copper circuit pattern.

[0040] S3. Plating the exposed thick copper lines and holes with thick copper. The electroplating parameters are: current density 16-42 ASF, electroplating time 60-320 min, so that the copper thickness reaches the copper thickness requirement of the thick copper area, thereby obtaining a stepped circuit board.

[0041] S4. Remove the protective film and obtain the stepped circuit after etching. Use alkaline etching solution to etch the production board in a vacuum environment. The etching parameters are: etching pressure 2.5kg / cm 2 , etching speed 6-9m / min, then stripping tin;

[0042] S5. Performing solder mask, surface treatment and forming steps on the stepped circuit board in sequence to obtain a stepped thick copper circuit board.

[0043] The copper thickness of the thin copper area is 12-22 μm.

[0044] The difference in copper thickness between the thin copper area and the thick copper area is greater than 20 μm

[0045] The present invention provides an electroplating method for a stepped thick copper circuit board. The outer copper surface of the circuit board is electroplated throughout the board, so that the copper thickness meets the copper thickness requirement of the thin copper area. The thin copper area is first made and then the thick copper area is made. This method not only meets the precision requirement of the thin copper area, but also achieves higher copper thickness uniformity and copper thickness precision. The process is simple and the reliability is good. Two or more layers of 2 mil dry film are used in the film rolling process, which effectively solves the quality problem of the film sandwich. At the same time, a protective film is used to cover the circuit area that does not need to be thickened, so as to prevent the thin copper circuit pattern from being electroplated when the copper layer is electroplated on the surface of the thick copper circuit pattern. At the same time, the protective film is laser cut at the boundary between the thin copper circuit pattern and the thick copper circuit pattern, so that the junction between the thin copper circuit and the thick copper circuit pattern can be smooth and neat. The surface of the stepped circuit board is etched, and then a solder mask layer is made, a surface treatment and a molding process are performed. The quality problems such as circuit gaps and incomplete etching caused by the inability to make the anti-corrosion layer and the circuit closely attached when using the dry film process are effectively solved. The entire production process is compatible with the traditional circuit board process, has low cost and high economic benefits.

[0046] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A plating method for a stepped thick copper circuit board, characterized in that: It includes the following steps: S1. Conduct full-panel electroplating on the outer copper surface of the circuit board to make the copper thickness meet the copper thickness requirement of the thin copper area; S2. Through processes of laminating film, exposure, and development, develop the stepped circuit pattern, cover the areas where the circuit does not need to be thickened with a protective film, and expose the thick copper circuits and holes; S3. Electroplate the exposed thick copper circuits and holes to make the copper thickness meet the copper thickness requirement of the thick copper area, obtaining a stepped circuit board; S4. Remove the protective film, obtain the stepped circuit through etching treatment, and then remove the tin; S5. Successively perform solder mask making, surface treatment, and shaping processes on the stepped circuit board to obtain a stepped thick copper circuit board.

2. The electroplating method of a stepped thick copper circuit board according to claim 1, wherein: The copper thickness of the thin copper area is 12 - 22 μm.

3. The electroplating method of a stepped thick copper circuit board according to claim 1, characterized in that: The copper thickness difference between the thin copper area and the thick copper area is greater than 20 μm.

4. The electroplating method of a stepped thick copper circuit board according to claim 1, characterized in that: In S1, the electroplating parameters are: current density 8 - 22 ASF, electroplating time 36 - 120 min.

5. The electroplating method of a stepped thick copper circuit board according to claim 1, characterized in that: In the step S2, the film laminating process uses a protective film with a thickness of more than 2 mils in two or more layers, and the parameters of the laminating plate are as follows: the laminating plate pressure is 4 ± 1 kg / cm 2 , the temperature of the hot laminating roller is 100 ± 10 °C, the speed of the laminating plate is 2.6 ± 0.3 m / min, and the temperature of the plate out is 42 - 58 °C.

6. The electroplating method of a stepped thick copper circuit board according to claim 1, characterized in that: In S2, the protective film is a PVC electroplating blue film.

7. The electroplating method of a stepped thick copper circuit board according to claim 1, characterized in that: In S2, covering the areas where the circuit does not need to be thickened with a dry film and exposing the thick copper circuits and holes specifically includes: S201. Press the protective film on the stepped circuit pattern; S202. Perform laser film cutting on the protective film at the boundary between the thin copper circuit pattern and the thick copper circuit pattern; S203. Remove the protective film on the surface of the thick copper circuit pattern.

8. The electroplating method of a stepped thick copper circuit board according to claim 1, characterized in that: In S3, the electroplating parameters are: current density 16 - 42 ASF, electroplating time 60 - 320 min.

9. The electroplating method of a stepped thick copper circuit board according to claim 1, characterized in that: In the step S4, an alkaline etching solution is used to etch the production board in a vacuum environment, and the parameters during etching are: etching pressure 2.5 kg / cm 2 , etching speed 6 - 9 m / min.