[Repost] A brief analysis of common errors in PCB design
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I. Common errors in schematics (1) ERC reports that the pin is not connected to the signal: a. The I/O properties of the pin were defined when the package was created; b. Inconsistent grid properties were modified when creating or placing components, and the pin was not connected to the line; c. The pin direction was reversed when creating the component, and it must be non-pin d. The most common reason is that the project file is not created, which is the easiest mistake for beginners. (2) The component runs out of the drawing: the component is not created in the center of the component library chart paper. (3) The network list of the created project file can only be partially loaded into PCB: global was not selected when generating the netlist. (4) When using multi-part components created by yourself, never use annotate. (2) Common errors in PCB (1) Report NODE not found when loading the network (a) Report NODE not found when loading the network (b) Report NODE not found when loading the network (c) Report NODE not found when loading the network (d ... The components in the schematic diagram use packages that are not in the PCB library; b. The components in the schematic diagram use packages with inconsistent names in the PCB library; c. The components in the schematic diagram use packages with inconsistent pin numbers in the PCB library. For example, for a transistor, the pin numbers in sch are e, b, c, while those in PCB are 1, 2, 3. (2) Printing cannot always fit on one page a. The origin was not at the time of creating the PCB library; b. The components were moved and rotated many times, and there were hidden characters outside the PCB board boundary. Select to show all hidden characters, shrink the PCB, and then move the characters into the boundary. (3) The DRC report network is divided into several parts: indicates that this network is not connected. Look at the report file and use the CONNECTED COPPER selection to search. If you make a more complex design, try not to use automatic routing. Three, Common Errors in PCB Manufacturing Process [color=rgb(25, 25, (25)]（1）Pad overlap a. Causes double holes. When drilling, multiple holes in one place lead to broken drills and hole damage. b. In a multi-layer board, there are both connection pads and isolation pads at the same position. The board appears to be isolated and the connection is wrong. （2）Improper use of graphic layers a. Violation of conventional design, such as designing the component surface on the Bottom layer and the welding surface on the Top layer, which causes misunderstanding. b. There are a lot of design garbage on each layer, such as broken wires, useless borders, and annotations. （3）Irrational characters a. The characters cover the SMD solder pads, which brings inconvenience to PCB continuity detection and component welding. b. The characters are too small, making screen printing difficult, and too large will cause the characters to overlap each other.It is difficult to distinguish. The font is generally >40mil. (4) Setting the aperture of a single-sided pad a. Single-sided pads are generally not drilled, and their aperture should be designed to be zero, otherwise the coordinates of the hole will appear at this position when the drilling data is generated. If drilling is required, special instructions should be given. b. If a single-sided pad needs to be drilled, but the aperture is not designed, the software will treat this pad as an SMT pad when outputting electrical and ground data, and the isolation pad will be lost in the inner layer. [color=rgb(25, 25, (25)](5) Although the pad is drawn with a filler block, it can pass the DRC check, but the solder mask data cannot be directly generated during processing. The pad is covered with solder mask and cannot be soldered. (6) The electrical layer is designed with both heat sink and signal line. The positive and negative graphics are designed together, which causes errors. (7) The grid spacing of a large area is too small. The grid line spacing is <0.3mm. In the PCB manufacturing process, the graphic transfer process produces broken film after development, causing broken lines. This increases the difficulty of processing. (8) If the graphic is too close to the outer frame, a distance of at least 0.2mm should be ensured (more than 0.35mm at the V-cut), otherwise the copper foil will be lifted and the solder resist will fall off during the external processing, affecting the appearance quality (including the inner copper skin of the multilayer board). (9) The design of the outer frame is not clear. Many layers have designed frames, and they do not overlap, making it difficult for PCB manufacturers to determine which line to form. The standard frame should be designed on the mechanical layer or BOARD layer, and the internal hollowing area should be clear. (10) Uneven graphic design causes uneven current distribution during graphic electroplating, affecting the uniformity of the coating and even causing warping. (11) Short special-shaped holes The length/width of special-shaped holes should be >2:1, and the width should be >1.0mm, otherwise the CNC drilling machine cannot process them. (12) Milling contour positioning holes are not designed If possible, design at least 2 positioning holes with a diameter >1.5mm in the PCB board. (13) The aperture marking is unclear a. The aperture marking should be marked in metric as much as possible, and increase by 0.05. b. For apertures that can be combined, merge them into one storage area as much as possible. c. Whether the tolerances of metallized holes and special holes (such as crimping holes) are clearly marked. (14) The inner layer routing of the multi-layer board is unreasonable. a. The heat dissipation pad is placed on the isolation tape, which may cause the connection to fail after drilling. b. The isolation belt design has a gap, which is easy to be misunderstood. c. The isolation belt design is too narrow and cannot accurately judge the network (15) Design problems of buried and blind vias The significance of designing buried and blind vias: a. Increase the density of multilayer boards by 30% Above, reduce the number of layers and size of multilayer boards b. Improve PCB performance, especially the control of characteristic impedance (shortening wires and reducing apertures) c. Improve PCB design freedomd. Reduce raw materials and costs, which is beneficial to environmental protection. Others attribute these problems to work habits. People who have problems often have these bad habits. Lack of Planning As the saying goes, "If a man does not plan beforehand, he will find trouble coming to him." This certainly applies to PCB design. One of the many steps that can make PCB design a success is choosing the right tools. Today's PCB design engineers can find many powerful and easy-to-use EDA packages on the market. Each has its own unique capabilities, advantages and limitations. In addition, it should be noted that no software is foolproof, so problems such as component footprint mismatches are bound to occur. It is possible that no single tool will meet all of your needs, but even so, you must do your research beforehand and try to find the best product that best suits your needs. Some information on the Internet can help you get started quickly. Poor Communication Although outsourcing the design of PCBs to other manufacturers is becoming more and more common and often very cost-effective, this practice may not be suitable for highly complex PCB designs where performance and reliability are critical. As design complexity increases, face-to-face communication between engineers and PCB designers becomes increasingly important to ensure accurate component placement and routing in real time. This face-to-face communication will help save expensive rework later. It is also important to involve the PCB board manufacturer in the early stages of the design process. They can provide initial feedback on your design, and they can maximize efficiency based on their processes and procedures, which will help you save considerable time and money in the long run. By letting them know your design goals and involving them in the early stages of PCB layout, you can avoid any potential problems before your product goes into production and shorten your time to market. Failure to Thoroughly Test Early Prototypes Prototype boards allow you to prove that your design is working according to original specifications. Prototype testing allows you to verify the functionality and quality of the PCB and its performance before mass production. Successful prototype testing requires a lot of time and experience, but a strong test plan and a clear set of goals can shorten the evaluation time and also reduce the possibility of production-related errors. If any problems are found during prototype testing, a second test on a reconfigured board will be required. Incorporating high-risk factors early in the design process will benefit from multiple iterations of testing, identify any potential problems early, reduce risk, and ensure that the plan can be completed on time. Using inefficient layout techniques or incorrect components Smaller, faster devices require PCB designers to layout complex designs that will use smaller components to reduce the footprint and they will also be placed closer together. Using techniques such as embedded discrete devices on internal PCB layers or ball grid array (BGA) packages with a smaller pin pitch will help reduce board size, improve performance, and preserve space for rework if problems are encountered. When working with components with high pin counts and smaller pitches, it is important to choose the right board layout techniques at design time to avoid problems later and minimize manufacturing costs. Also, be sure to carefully research the range and performance characteristics of the replacement components you plan to use, even those that are labeled as drop-in replacements. Minor changes in the characteristics of a replacement component may be enough to mess up the performance of the entire design. Forget to back up your work. Need I remind you? At the very least, you should back up your most important work and other irreplaceable files. While most companies back up all of their data on a daily basis, smaller companies may not do so, or if you work from home. With backing up your data to the cloud so convenient and inexpensive these days, there really is no excuse not to back up your data and keep it in a safe place to protect it from theft, fire, and other local disasters. Become a Solo Island Although you may think your designs are flawless and making mistakes is simply not your style, many times your peers will see something wrong in your design that you didn't notice. Sometimes, even if you know the intricacies of a design, someone with less exposure to it may be able to maintain a more objective attitude and provide valuable insights. Reviewing your designs frequently with your peers can help find unforeseen problems and keep your plans on track and within budget. Of course, mistakes are inevitable, but as long as you learn from them, you can design a better product next time. 25)]Failure to thoroughly test early prototypes Prototype boards allow you to prove that your design is working according to original specifications. Prototype testing allows you to verify the functionality and quality of the PCB and its performance before mass production. Successful prototype testing requires a lot of time and experience, but a strong test plan and a clear set of goals can shorten the evaluation time and also reduce the possibility of production-related errors. If any problems are found during prototype testing, a second test will need to be performed on a reconfigured board. Incorporating high-risk factors early in the design process will benefit from multiple iterations of testing, identify any potential problems early, reduce risks, and ensure that the plan can be completed on time. Using inefficient layout techniques or incorrect components Smaller, faster devices require PCB designers to layout complex designs that will use smaller components to reduce the footprint and they will also be placed closer together. Using techniques such as embedded discrete devices on internal PCB layers or ball grid array (BGA) packages with a smaller pin pitch will help reduce board size, improve performance, and preserve space for rework if problems are encountered. When working with components with high pin counts and smaller pitches, it is important to choose the right board layout techniques at design time to avoid problems later and minimize manufacturing costs. Also, be sure to carefully research the range and performance characteristics of the replacement components you plan to use, even those that are labeled as drop-in replacements. Minor changes in the characteristics of a replacement component may be enough to mess up the performance of the entire design. Forget to back up your work. Need I remind you? At the very least, you should back up your most important work and other irreplaceable files. While most companies back up all of their data on a daily basis, smaller companies may not do so, or if you work from home. With backing up your data to the cloud so convenient and inexpensive these days, there really is no excuse not to back up your data and keep it in a safe place to protect it from theft, fire, and other local disasters. Become a Solo Island Although you may think your designs are flawless and making mistakes is simply not your style, many times your peers will see something wrong in your design that you didn't notice. Sometimes, even if you know the intricacies of a design, someone with less exposure to it may be able to maintain a more objective attitude and provide valuable insights. Reviewing your designs frequently with your peers can help find unforeseen problems and keep your plans on track and within budget. Of course, mistakes are inevitable, but as long as you learn from them, you can design a better product next time. 25)]Failure to thoroughly test early prototypes Prototype boards allow you to prove that your design is working according to original specifications. Prototype testing allows you to verify the functionality and quality of the PCB and its performance before mass production. Successful prototype testing requires a lot of time and experience, but a strong test plan and a clear set of goals can shorten the evaluation time and also reduce the possibility of production-related errors. If any problems are found during prototype testing, a second test will need to be performed on a reconfigured board. Incorporating high-risk factors early in the design process will benefit from multiple iterations of testing, identify any potential problems early, reduce risks, and ensure that the plan can be completed on time. Using inefficient layout techniques or incorrect components Smaller, faster devices require PCB designers to layout complex designs that will use smaller components to reduce the footprint and they will also be placed closer together. Using techniques such as embedded discrete devices on internal PCB layers or ball grid array (BGA) packages with a smaller pin pitch will help reduce board size, improve performance, and preserve space for rework if problems are encountered. When working with components with high pin counts and smaller pitches, it is important to choose the right board layout techniques at design time to avoid problems later and minimize manufacturing costs. Also, be sure to carefully research the range and performance characteristics of the replacement components you plan to use, even those that are labeled as drop-in replacements. Minor changes in the characteristics of a replacement component may be enough to mess up the performance of the entire design. Forget to back up your work. Need I remind you? At the very least, you should back up your most important work and other irreplaceable files. While most companies back up all of their data on a daily basis, smaller companies may not do so, or if you work from home. With backing up your data to the cloud so convenient and inexpensive these days, there really is no excuse not to back up your data and keep it in a safe place to protect it from theft, fire, and other local disasters. Become a Solo Island Although you may think your designs are flawless and making mistakes is simply not your style, many times your peers will see something wrong in your design that you didn't notice. Sometimes, even if you know the intricacies of a design, someone with less exposure to it may be able to maintain a more objective attitude and provide valuable insights. Reviewing your designs frequently with your peers can help find unforeseen problems and keep your plans on track and within budget. Of course, mistakes are inevitable, but as long as you learn from them, you can design a better product next time.
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