Machining method for small spacing between metal covered edge and surface pattern

Abstract

The invention discloses a processing method for a small space between a metal covered edge and a surface pattern, relates to the technical field of PCB processing, can realize the small space between the metal covered edge and the surface pattern to be less than 5mil, and avoids the problems of film flying, incomplete etching and the like in an optical imaging transfer process. The invention discloses a machining method for a small distance between a metal covered edge and a surface pattern. The machining method comprises the following steps of cutting, laminating, drilling, copper deposition, hole milling before hole forming, external light imaging, copper and tin plating, laser tin burning, alkaline etching, solder mask printing, surface treatment, testing, edge milling and final inspection. The positions of the patterns and the metal covered edges and the positions of the patterns are firstly integrally tinned, and then the laser tin burning process is adopted to solve the difficulty in processing small intervals between the metal covered edges and the surface patterns in the existing optical imaging transfer process, so that the problems of film flying and incomplete etching are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of PCB processing, and in particular to a method for processing a metal edging and a small spacing between surface patterns. Background Art

[0002] In the PCB processing technology, the metal edging process is a process that can provide electromagnetic interference (EMI) and radio frequency interference (RFI) shielding effects, reduce the impact of external interference on the circuit board, and ensure the stability and reliability of the circuit. This process refers to coating a layer of metal material around the PCB board, so that microwave signals cannot radiate from the edge of the PCB board. This process is widely used in high-speed and high-frequency PCB circuit boards. The industry often uses dry film to transfer through optical imaging. The overall trend of circuit boards is developing towards high precision, and the spacing between graphics is set to be smaller and smaller. Generally, the spacing between the metal edging and the surface graphics is designed to be more than 8mil, but when the spacing between the metal edging and the surface graphics is small (≤5mil), there are problems such as flying film and incomplete etching, which causes the metal edging and the surface graphics to short-circuit, resulting in electrical performance failure. Such difficulties are difficult to solve with conventional optical imaging processes. Summary of the invention

[0003] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art, and to provide a processing method for a small pitch between a metal edging and a surface pattern, which can achieve a small pitch between the metal edging and the surface pattern of less than 5 mil, and avoid problems such as flying film and incomplete etching in the optical imaging transfer process.

[0004] The present invention provides a method for processing a small spacing between a metal edging and a surface pattern, comprising the following steps: cutting → laminating → drilling → copper deposition → milling holes before hole formation → external light imaging → copper tin plating → laser tinning → alkaline etching → printing solder resist → surface treatment → testing → milling → final inspection.

[0005] A method for processing a small spacing between a metal edging and a surface pattern according to an embodiment of the present invention has at least the following beneficial effects: A method for processing a small spacing between a metal edging and a surface pattern, comprising the following steps: cutting → lamination → drilling → copper deposition → milling holes before hole formation → external light imaging → copper tin plating → laser tinning → alkaline etching → solder mask printing → surface treatment → testing → milling → final inspection. The difficulty of processing a small spacing between the metal edging and the surface pattern in the existing optical imaging transfer process is solved by first tinning the entire position of the pattern and the metal edging and the pattern position, and then using the laser tinning process, which effectively solves the problems of flying film and incomplete etching.

[0006] According to the method for processing a small spacing between a metal edging and a surface pattern described in the present invention, in the step of milling holes before hole forming, the metal edging position designed for the printed circuit board is first milled out to facilitate the subsequent plating of metal during copper-tin plating.

[0007] According to the method for processing a metal edging and a surface pattern with a small pitch described in the present invention, in the external light imaging step, a dry film is firstly covered on the surface of the printed circuit board, and then the pattern is produced by the light imaging transfer technology.

[0008] According to the method for processing a small spacing between a metal edging and a surface pattern described in the present invention, in the external light imaging step, a dry film is firstly covered on the surface of the printed circuit board, and it is necessary to ensure that the spacing between the metal edging and the surface pattern is not covered with the dry film.

[0009] According to the method for processing a small spacing between a metal edging and a surface pattern described in the present invention, after the copper-tin plating step, the surface pattern, the metal edging, and the spacing between the metal edging and the surface pattern are all plated with copper, and then a layer of tin is plated on the surface of the copper.

[0010] According to the method for processing a small spacing between a metal cladding and a surface pattern described in the present invention, in the laser tinning step, the tin plating at the spacing position between the metal cladding and the surface pattern is burned off to expose the copper layer underneath.

[0011] According to the method for processing a small pitch between a metal edging and a surface pattern of the present invention, after the steps of laser tinning and alkaline etching, the pitch between the metal edging and the surface pattern is less than 5 mil.

[0012] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention is further described below in conjunction with the accompanying drawings and embodiments;

[0014] Figure 1 The process flow chart of the preferred embodiment of the present invention is as follows;

[0015] Figure 2 It is a schematic diagram of the board surface after the step of milling holes before hole forming in a preferred embodiment of the present invention;

[0016] Figure 3 It is a schematic diagram of the board surface after the dry film is plated in the external light imaging step in a preferred embodiment of the present invention;

[0017] Figure 4 This is a schematic diagram of the board surface after the copper-tin plating step in a preferred embodiment of the present invention;

[0018] Figure 5 This is a schematic diagram of the board surface after the laser tinning step in a preferred embodiment of the present invention;

[0019] Figure 6 FIG. 1 is a schematic diagram of the board surface after the alkaline etching step according to a preferred embodiment of the present invention.

[0020] Reference numerals: single board 10 , waste area 20 , pre-hole milling area 30 , graphic area 40 , dry film 50 , copper-tin plating layer 60 , tin layer 70 , metal edging 80 . DETAILED DESCRIPTION

[0021] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0022] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and 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 and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0023] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0024] 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.

[0025] Reference Figures 1 to 6 A method for processing a small spacing between a metal edging and a surface pattern comprises the following steps: cutting → lamination → drilling → copper deposition → milling holes before hole formation → external light imaging → copper tin plating → laser tinning → alkaline etching → solder mask printing → surface treatment → testing → edge milling → final inspection.

[0026] It can be understood that by first tinning the entire position of the graphic and the metal edging and the graphic position, and then using the laser tinning process to solve the difficulty of processing the small interval between the metal edging and the surface graphic in the existing optical imaging transfer process, the problems of flying film and unclean etching are effectively solved.

[0027] Furthermore, in the step of milling holes before hole forming, the metal edging position designed for the printed circuit board is first milled out to facilitate the subsequent metal plating during copper-tin plating.

[0028] Furthermore, in the external light imaging step, a dry film is firstly covered on the surface of the printed board, and then the pattern is produced by the light imaging transfer technology.

[0029] Furthermore, in the external light imaging step, the surface of the printed circuit board is first covered with a dry film, and it is necessary to ensure that the interval between the metal edging and the surface pattern is not covered with the dry film.

[0030] Furthermore, after the copper-tin plating step, the surface pattern, the metal edging, and the interval between the metal edging and the surface pattern are all plated with copper, and then a layer of tin is plated on the surface of the copper.

[0031] Furthermore, in the laser tinning step, the tin plating at the interval between the metal cladding and the surface pattern is burned off to expose the copper layer underneath.

[0032] Furthermore, after laser tinning and alkaline etching steps, the distance between the metal edging and the surface pattern is less than 5 mil.

[0033] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A method for processing a small spacing between a metal edging and a surface pattern, characterized in that: The following steps are involved: Cutting → lamination → drilling → copper plating → milling before hole forming → external light imaging → copper tin plating → laser tinning → alkaline etching → solder mask printing → surface treatment → testing → edge milling → final inspection.

2. A method for processing a small spacing between a metal edging and a surface pattern according to claim 1, characterized in that: In the milling step before hole processing, the metal edging position of the printed circuit board is milled out first to facilitate the subsequent copper-tin plating.

3. The method for processing a small spacing between a metal edging and a surface pattern according to claim 1, characterized in that: In the external light imaging step, the surface of the printed board is first covered with a dry film, and then the pattern is produced through light imaging transfer technology.

4. A method for processing a small spacing between a metal edging and a surface pattern according to claim 3, characterized in that: In the external light imaging step, the surface of the printed circuit board is first covered with a dry film, and it is necessary to ensure that the interval between the metal edge and the surface pattern is not covered with the dry film.

5. The method for processing a metal edging and a small pitch between surface patterns according to claim 1, characterized in that: After the copper-tin plating step, the surface pattern, the metal edging, and the interval between the metal edging and the surface pattern are all plated with copper, and then a layer of tin is plated on the surface of the copper.

6. The method for processing a metal edging and a small pitch between surface patterns according to claim 1, characterized in that: In the laser tinning step, the tin plating at the interval between the metal cladding and the surface pattern is burned off to expose the copper layer underneath.

7. The method for processing a metal edging and a small pitch between surface patterns according to claim 1, characterized in that: After laser tinning and alkaline etching steps, the distance between the metal edging and the surface pattern is less than 5 mil.

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