A method for quickly checking the deviation of PCB forming gong plate
By making offset reference lines on the PCB production board and detecting the remaining line width in the copper-free area, the offset problem of the PCB was solved, and the product quality and yield rate were improved.
Patent Information
- Application Number
- CN202410254729.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-06
- Publication Date
- 2025-10-03
- Estimated Expiration
- 2044-03-06
AI Technical Summary
During the PCB forming gong plate process, due to the material and process characteristics, the expansion and shrinkage coefficient of the previous process does not match the actual expansion and shrinkage coefficient, resulting in the gong plate being offset, causing the first piece to be qualified but defects to occur during the process, affecting product quality and yield rate.
Make deviation reference lines at the four corners of the production board, and open windows at the solder mask layer to reveal the deviation reference lines. By controlling the depth of the gong plate to form a copper-free area, the remaining line width on both sides of the copper-free area is detected to confirm the deviation and direction of the gong plate, and the gong belt coefficient of the gong knife is adjusted to correct the deviation.
By quickly inspecting the misalignment, we can avoid the first piece passing while the misalignment occurs during the process, thus improving product quality and yield rate.
Smart Images
Figure CN118158900B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of printed circuit board production, and in particular to a method for quickly detecting the deviation of a PCB forming gong plate. Background Art
[0002] PCB gong board forming is a common machining method. The board from the previous process is placed on the gong machine, and the high-speed rotation and vacuum adsorption of the gong knife are used to separate the copper foil and the substrate on the circuit board, thereby realizing the forming of the circuit board. When making the gong board in the forming process, the gong board operation needs to be performed according to the expansion and contraction coefficient provided by the previous process. This processing method has the advantages of high efficiency and low cost, and is widely used in the PCB manufacturing industry.
[0003] However, the above production method has the following disadvantages:
[0004] 1. Due to the characteristics of materials, processes, etc. during the PCB production process, some processes produce different amounts of expansion and contraction. If the operation is only based on the expansion and contraction coefficient of the previous process, there will be a large mismatch between the expansion and contraction coefficient of the previous process and the actual expansion and contraction coefficient during the PCB production process. If the production process is completely based on the expansion and contraction coefficient provided by the previous process, it is very easy to cause the product to be scrapped due to deviation.
[0005] 2. When the forming gong plate is produced as the first piece according to the expansion and shrinkage coefficient, the first unit plate is located at the design zero position of the entire plate, and the expansion and shrinkage is minimal. In subsequent production, if other units are produced according to the initial expansion and shrinkage coefficient, the deviation amount cannot be monitored during the production process, and there may be a qualified first piece and some defects in the process, which affects the product quality. Summary of the Invention
[0006] In response to the above-mentioned existing technical defects, the present invention provides a method for quickly checking the deviation of PCB forming gong plates. This method can quickly check the deviation of the incoming board before forming, facilitate timely adjustment of the expansion and contraction of the forming gong plate, avoid the phenomenon that the first piece is qualified but the process deviation is unqualified, and improve product quality and production yield.
[0007] In order to solve the above technical problems, the present invention provides a method for quickly checking the deviation of a PCB forming gong plate, comprising the following steps:
[0008] S1. When making the outer layer circuit on the production board, a deflection reference line is made at the four corners of the board edge. The line width of the deflection reference line is larger than the blade width of the gong knife when forming the gong board;
[0009] S2. Making a solder mask layer on the production board, and opening a window in the solder mask layer at a position corresponding to the offset reference line to reveal the offset reference line;
[0010] S3, use a forming gong cutter to control the depth of the gong plate at the middle position of the corresponding offset reference line, and use the gong to remove the offset reference line at the corresponding position to form a copper-free area;
[0011] S4. Determine whether there is any deviation of the gong plate and the direction of deviation based on the remaining line width on both sides of the copper-free area.
[0012] Furthermore, in step S1, the width of the offset reference line is 0.1 mm larger than the blade width of the gong knife when forming the gong plate.
[0013] Furthermore, in step S1, the width of the offset reference line is 0.2 mm.
[0014] Furthermore, in step S3, the blade width of the gong knife is 0.1 mm.
[0015] Furthermore, in step S1, the offset reference lines are in a right-angle shape, and the offset reference lines set at the four corners of the production board are distributed symmetrically around the center.
[0016] Furthermore, in step S3, when the offset reference line is gonged, gong is performed from one end of the offset reference line to the other end to gong out a copper-free area on the offset reference line.
[0017] Furthermore, in step S3, the thickness of the gong plate when controlling the depth is greater than or equal to the thickness of the offset reference line.
[0018] Furthermore, in step S4, it is detected whether the remaining line widths on both sides of the copper-free area are consistent, so as to confirm whether there is a deviation of the gong plate and the direction of the deviation.
[0019] Furthermore, in step S4, when the remaining line widths on both sides of the copper-free area are consistent, the production board is directly subjected to forming gong plate processing according to the design requirements; when the remaining line widths on both sides of the copper-free area are inconsistent, the offset amount and offset direction during gong plate processing are obtained according to the remaining amount of line width on both sides, thereby obtaining the expansion and shrinkage coefficient of the production board, and then adjusting the gong strip coefficient of the gong knife according to the expansion and shrinkage coefficient, and then performing forming gong plate processing on the production board according to the adjusted gong strip coefficient.
[0020] Furthermore, the production board is a multi-layer board in which an inner core board and an outer copper foil are pressed together by a prepreg, and the multi-layer board has undergone drilling, copper deposition and full-board electroplating processes in sequence.
[0021] Compared with the prior art, the present invention has the following beneficial effects:
[0022] In the present invention, first, a deviation reference line is added at the four corners of the production board; before the first gong plate is produced, a gong cutter is used to normally compensate the middle position of the gong deviation reference line according to the expansion and contraction coefficient of the incoming production board, and the presence of gong plate deviation and the deviation direction are confirmed according to the remaining line width on both sides of the copper-free area. After confirming the deviation result, it is convenient to adjust the expansion and contraction amount during the subsequent molding gong plate production in a timely manner, avoiding the phenomenon of qualified first piece and poor process deviation during the production process, thereby improving product quality and production yield. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 This is a schematic diagram of the embodiment after the offset reference lines are made at the four corners of the production board;
[0024] Figure 2 Schematic diagram of the embodiment after the copper-free area is gonged out on the offset reference line. DETAILED DESCRIPTION
[0025] In order to more fully understand the technical content of the present invention, the technical solution of the present invention will be further introduced and illustrated in conjunction with specific embodiments below.
[0026] Example
[0027] The present embodiment shows a method for manufacturing a circuit board, which includes a process for solder resisting with a variegated ink, and includes the following processing steps in sequence:
[0028] (1) Cutting: Cut the core board according to the panel size of 520mm×620mm. The thickness of the core board is 0.5mm, and the thickness of the copper layer on both surfaces of the core board is 0.5oz.
[0029] (2) Inner layer circuit production (negative film process): Inner layer pattern transfer, use a vertical coating machine to coat the photosensitive film, the film thickness of the photosensitive film is controlled at 8μm, and a fully automatic exposure machine is used to complete the exposure of the inner layer circuit with a 5-6 grid exposure ruler (21 grid exposure ruler), and the inner layer circuit pattern is formed after development; inner layer etching, the exposed and developed core board is etched to etch the inner layer circuit, and the inner layer line width is measured to be 3mil; inner layer AOI, and then check the inner layer circuit for defects such as open and short circuits, circuit gaps, and circuit pinholes. Defective products will be scrapped, and products without defects will be sent to the next process.
[0030] (3) Lamination: The browning speed is based on the browning thickness of the bottom copper. The core board, prepreg, and outer copper foil are laminated in sequence as required. Then, appropriate lamination conditions are selected according to the Tg of the sheet material to press the laminated board to form a production board.
[0031] (4) Drilling: Based on existing drilling technology, drilling is performed on the production board according to design requirements.
[0032] (5) Copper plating: A thin layer of copper is deposited on the board surface and the hole wall using the chemical copper plating method. The backlight test is level 10, and the thickness of the copper plating in the hole is 0.5μm.
[0033] (6) Full-board electroplating: Full-board electroplating is performed at a current density of 18ASF for 120 minutes to thicken the copper layer on the hole and the board surface.
[0034] (7) Production of outer layer circuit (positive process): Transfer of outer layer pattern, using fully automatic exposure machine and positive circuit film, with 5-7 grid exposure ruler (21 grid exposure ruler) to complete outer layer circuit exposure, after development, the outer layer circuit pattern is formed on the production board, the outer layer circuit pattern includes the offset reference line pattern located at the four corners of the board edge; the outer layer pattern is electroplated, and then copper and tin are plated on the production board respectively. The electroplating parameters are set according to the required copper thickness. Copper plating is performed at a current density of 1.8ASD for 60 minutes on the entire board, and tin plating is performed at a current density of 1.2ASD for 10 minutes, with a tin thickness of 3-5μm; then the film is stripped, etched and tin stripped in sequence, and the outer layer circuit and an offset reference line 1 are etched at the four corners on the production board (such as Figure 1 Outer layer AOI uses an automatic optical inspection system to detect defects such as open circuits, gaps, incomplete etching, and short circuits on the outer layer by comparing it with CAM data.
[0035] In one embodiment, the line width of the offset reference line is greater than the blade width of the gong knife when forming the gong plate; preferably, the line width of the offset reference line is 0.1 mm greater than the blade width of the gong knife when forming the gong plate.
[0036] Preferably, the width of the offset reference line is 0.2 mm, and the blade width of the gong knife is 0.1 mm.
[0037] In one embodiment, if Figure 1 As shown, the deviation reference line 1 is a right-angled line, and the deviation reference lines set at the four corners of the production board are distributed symmetrically around the center. This structure can better measure the deviation direction and deviation amount at various locations on the production board, and the inner right-angled sides of the deviation reference lines are all set inward.
[0038] (8) Solder mask and silk screen characters: After silk screen printing solder mask ink on the surface of the production board, it is sequentially processed by pre-curing, exposure, development and heat curing to solidify the solder mask ink into a solder mask layer, and the solder mask layer is opened at the position corresponding to the offset reference line to reveal the offset reference line; specifically, the solder mask ink on the TOP surface and the characters on the TOP surface are added with a "UL" mark, so that a layer is coated on the circuits and substrates that do not need to be soldered to prevent bridging between circuits during soldering, provide a permanent electrical environment and chemical corrosion resistance, and at the same time beautify the appearance.
[0039] (9) Surface treatment (nickel-gold deposition): The copper surface of the pad at the solder mask window position is chemically deposited with a nickel layer and a gold layer of a certain required thickness. The nickel layer thickness is 3-5μm; the gold layer thickness is 0.05-0.1μm.
[0040] In one embodiment, in order to reduce costs, a plating resist can be first made on the offset reference line to avoid plating a nickel-gold layer on the offset reference line; the plating resist can preferably be a dry film, which is then affixed to the board and then obtained by exposure and development.
[0041] (10) Electrical test: Test the electrical conductivity of the finished board. The test method used for this board is: flying probe test.
[0042] (11) Forming: When making the first board, first compensate the gong belt coefficient according to the expansion and contraction coefficient of the production board when the material is received. Use the forming gong knife to control the depth of the gong plate at the middle position of each deviation reference line, and gong the deviation reference line at the corresponding position to form a copper-free area 2 (such as Figure 2 As shown); by detecting whether the remaining line width on both sides of the copper-free area is consistent, it is confirmed whether there is a gong plate deviation and the deviation direction; when the remaining line width on both sides of the copper-free area is consistent, the production board is directly subjected to forming gong plate processing according to the original gong tape coefficient according to the design requirements to gong out the shape; when the remaining line width on both sides of the copper-free area is inconsistent, the deviation amount and deviation direction during gong plate processing are obtained according to the remaining amount of line width on both sides, so as to obtain the actual expansion and contraction coefficient of the production board, and then the gong tape coefficient of the gong knife is adjusted according to the expansion and contraction coefficient, and then the first board and subsequent production boards are subjected to forming gong plate processing according to the adjusted gong tape coefficient to gong out the shape, with an shape tolerance of + / -0.05mm to obtain a circuit board.
[0043] In one embodiment, when the reference line is offset, the tool path is also perpendicular to the offset reference line, so as to form a right-angled copper-free area (such as a right-angled copper-free area) on the offset reference line. Figure 2 shown).
[0044] In one embodiment, the thickness of the gong plate when controlling the depth is greater than or equal to the thickness of the offset reference line, ensuring that the offset reference line in the copper-free area is removed.
[0045] In one embodiment, when forming and manufacturing each production board, the actual expansion and contraction coefficient of the board is first determined by the reference line of the gong deviation, and then the gong belt coefficient of the gong knife is adjusted according to the expansion and contraction coefficient, and then the production board is formed and gonged according to the adjusted gong belt coefficient, which can further improve the production quality of each production board.
[0046] (12) FQC: Inspect the appearance of the circuit board according to the customer's acceptance standards and our inspection standards. If there are any defects, repair them in time to ensure that we provide customers with excellent quality control.
[0047] (13) FQA: Re-test the appearance, hole copper thickness, dielectric layer thickness, green oil thickness, inner layer copper thickness of the circuit board to see if they meet the customer's requirements.
[0048] (14) Packaging: According to the packaging method and packaging quantity required by the customer, the circuit board is sealed and packed, and desiccant and humidity card are placed before shipment.
[0049] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, according to the embodiments of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.
Claims
1. A method for quickly checking the deviation of PCB forming gong plate, characterized in that: The following steps are involved: S1. When producing the outer layer circuit on the production board, a deflection reference line is made at each of the four corners of the board edge. The line width of the deflection reference line is larger than the blade width of the gong knife when forming the gong board. The deflection reference line is a right angle, and the deflection reference lines set at the four corners of the production board are distributed symmetrically around the center. S2. Making a solder mask layer on the production board, and opening a window in the solder mask layer at a position corresponding to the offset reference line to reveal the offset reference line; S3, use a forming gong cutter to control the depth of the gong plate at the middle position of the corresponding offset reference line, and use the gong to remove the offset reference line at the corresponding position to form a copper-free area; S4. Confirm whether there is gong plate deviation and deviation direction according to the remaining line width on both sides of the copper-free area; detect whether the remaining line width on both sides of the copper-free area is consistent to confirm whether there is gong plate deviation and deviation direction. When the remaining line width on both sides of the copper-free area is consistent, the production board is directly subjected to forming gong plate processing according to the design requirements; when the remaining line width on both sides of the copper-free area is inconsistent, the deviation amount and deviation direction of the gong plate are obtained according to the remaining amount of the line width on both sides, thereby obtaining the expansion and contraction coefficient of the production board, and then adjusting the gong belt coefficient of the gong knife according to the expansion and contraction coefficient, and then performing forming gong plate processing on the production board according to the adjusted gong belt coefficient.
2. The method for quickly checking the deviation of PCB forming gong plate according to claim 1, characterized in that: In step S1, the width of the offset reference line is 0.1 mm larger than the blade width of the gong knife when forming the gong plate.
3. The method for quickly checking the deviation of PCB forming gong plate according to claim 1, characterized in that: In step S1, the width of the offset reference line is 0.2 mm.
4. The method for quickly checking the deviation of PCB forming gong plate according to claim 3, characterized in that: In step S3, the blade width of the gong knife is 0.1 mm.
5. The method for quickly checking the deviation of PCB forming gong plate according to claim 1, characterized in that: In step S3, when the offset reference line is gonged, the gong is performed from one end of the offset reference line to the other end to gong out a copper-free area on the offset reference line.
6. The method for quickly checking the deviation of PCB forming gong plate according to claim 5, characterized in that: In step S3, the thickness of the gong plate when controlling the depth is greater than or equal to the thickness of the offset reference line.
7. The method for quickly checking the deviation of PCB forming gong plate according to claim 1, characterized in that: The production board is a multi-layer board in which an inner core board and an outer copper foil are pressed together by a semi-cured sheet, and the multi-layer board has undergone drilling, copper deposition and full-board electroplating processes in sequence.
Citation Information
Patent Citations
Routing method for micro PCB hard board
CN108513462A
Molding gong plate deviation monitoring method
CN116428958A