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This article provides a detailed introduction to PCB panel design principles, V-cut angle selection and its impact, layout planning, as well as process edges and limitations in V-cut design and use.V-CUT is a V-shaped groove cut at a specific position on the PCB board, which facilitates the separation of the assembled panel into individual boards after assembly. It is suitable for rectangular, square and other regular shaped PCB boards, while circular and irregular boards are more suitable for stamp hole connections
1 Design principles:
Board splitting safety: Plan the position, direction, and quantity of V-CUT to ensure that the board and components are not damaged during splitting.
Production process: The parameters such as V-cut angle and depth should comply with the manufacturer's processing capabilities and the performance of the slitting equipment.
Improve material utilization: Optimize V-CUT position and splicing method to reduce board waste. At the same time, ensure that the V-CUT direction is consistent with the panel arrangement, avoid crossing or slanting, and simplify the panel splitting operation
Consider the difficulty level of board splitting, whether to use a board splitting machine for analysis or manually open it. Manual splitting: prone to stress cracks, it is recommended to chamfer the edges; Machine board splitting: It is necessary to design guiding edges to improve the efficiency of automated board splitting.
2 V-cut angle
Commonly used 45 ° (30-60 °, often adjusted in stages of 5 °), due to its low plate stress and low risk of damage, it can also be adjusted according to plate thickness, material, and equipment.The larger the angle of V-Cut, the more boards the edges of the board are eaten by V-Cut, and the circuits on the PCB must be shrunk inward to avoid being cut by V-Cut or damaged during V-Cut cutting.The smaller the angle of V-Cut, the more advantageous it is for PCB space design in theory, but it is not conducive to the lifespan of V-Cut saw blades in PCB manufacturers, because the smaller the V-Cut angle, the thinner the blade of the electric saw, and the more likely it is to wear and break its blade
Depth: Generally 1/3-1/4 of the plate thickness, for example, for a 1.6mm thick plate, the cutting depth should be controlled at 0.4-0.5mm.
Distance between V-CUT wires and components: The distance between V-CUT wires and components should be ≥ 0.5mm. For sensitive components such as BGA and QFN, the recommended distance is ≥ 2mm.
Splicing gap: Reserve about 0.4mm between adjacent boards for easy processing and splitting.
3 Layout planning
The V-CUT line is preferably straight, avoiding complex routing and reducing processing difficulty and plate stress. At the same time, determine the V-CUT line position based on the PCB functional modules and component layout, and keep it away from critical areas. In addition, design a 5-10mm wide process edge and add positioning holes or reference marks, taking care to avoid conflicts between V-CUT and the process edge.
Splicing gap: Reserve about 0.4mm between adjacent boards for easy processing and splitting.
4 V-Cut Design and usage limitations
V-Cut Can only cut straight lines, and make one cut to the end, which means V-Cut It can only be cut into a straight line from head to tail, it cannot turn or change direction, nor can it cut a small section like a tailor's line and then jump off a small section before cutting again.
that is because V-Cut The groove is cut out using a chainsaw with two discs on top and bottom. secondly, PCB The thickness is too thin and not suitable for making V-Cut Groove, generally if the thickness is 1.0 mm The following boards are not recommended by Work Bear V-Cut Yes, this is because V-Cut The groove will damage the original PCB The structural strength, when designed V-Cut When heavy parts are placed on the board, the board becomes easily bent due to gravity, which is very unfavorable SMT The welding operation.
Additionally, PCB When passing through the high temperature of the reflow oven, the board itself will soften and deform due to the high temperature exceeding the glass transition temperature (Tg). If V-Cut Poor design of position and groove depth can lead to PCB The deformation will be more severe, which is not conducive to the secondary reflow process.
Master these V-CUT Design points that can make PCB Design more efficient and reliable.