PCB Design

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    From PCB Design to Fabrication & Assembly

    • PCB Design & Layout
    • Electronics Design & New Production Introduction
    • Component Sourcing & Turnkey PCB Assembly
    • Prototype & Small to Medium Volume Production
    • ISO9001:2015, Quality Certified
    • No MOQ & Competitive Pricing

    The General Introduction of PCB Design

    PCB design is significant and complex knowledge. The first printed circuit board and its design originated from a radio designed by Mr. Eisler. It has been 90 years since then, during which PCB has developed rapidly and matured step by step.
    • As we know, PCB design is greatly important for an electronic product in the application. Its basic structure is derived from the schematic diagram of the final product.
    • An integrated circuit board is formed through reasonable and ingenious circuit layout design and component layout design.
    • At the same time, if the schematic diagram is properly designed and excellent, the circuit performance and heat dissipation design are good.
    • And the product performance and life can be further improved, including saving the cost of subsequent product production, etc.
    • In addition to the layout of lines and components mentioned above, it also includes the layout of connecting lines and vias, especially the impact of layout on heat dissipation, which will directly affect the functionality and life of finished products.
    • Like single panels and HDI printed circuit boards, different end products also use different design methods. Simple single-panel and double-sided board products can usually be realized by manual design.
    • If we encounter high-frequency printed circuit boards, HDI printed circuit boards, military PCBs, and other products that are too complex and require too strong functionality and heat resistance, we need to use computers as design tools.

    The PCB Design Guide

    The first thing to pay attention to is the design of the size of the PCB. As we know, a larger size will increase more plates, which will directly affect the final production cost. Moreover, larger sizes will not only increase the problem of plates but also lead to some other problems. For example, too large a size will lead to greater impedance, longer lines during printing, and easier drying of plates, The maintenance cost of the side will also increase greatly. On the contrary, if the size of the design is too small, there will be many bad effects. For example, if the size is too small, the distance between components will be reduced. The primary problem is heat dissipation if the distance between components is too small.
    As the preface says, heat dissipation greatly affects the functional stability of the final product, including life. In addition, the distance between components is too close, which may also produce integrity interference. Therefore, the first problem is to confirm the size of the PCB. After confirming the size, the next step is to place and allocate the specific positions of components. Dealing with different types of components need to pay attention to different points. For example, high-frequency components, high-voltage components, and high-temperature components, including the male and female nature of some components, all need special attention. Their positions should be allocated reasonably, otherwise, if they are placed too close, they will interfere with each other, including compatibility problems between some components.
    The distribution of components is very important for a successful design. In addition, not only the design of functionality and compatibility but also the beautiful layout will improve the recognition and success of the product. Therefore, a PCB layout with both function compatibility and appearance will make the final PCBA more successful.

    Some Problems with the Layout of the Components

    Here are some problems that should be paid attention to in the layout of components.
    1. As mentioned before, too small spacing between components is easy to affect each other. Whether it is stability or compatibility, especially for some high-frequency and high-voltage components, a long distance should be maintained to protect the stability and safety of the whole line. In addition, low-voltage components and high-voltage components should also be kept away from high-voltage components as far as possible, otherwise, the gap is too large, and it is easy to form a short circuit or damage the circuit in use, and the high-voltage itself is dangerous. For the safety of users, it should also be distributed in a more remote location.
    2. Components with too heavy weight should be fixed and supported by auxiliary means. Components with a weight of more than 14g should be welded and supported by auxiliary means as far as possible, to avoid damage to components and circuit boards during transportation and use. Secondly, components with high heat should also be kept away from heat-sensitive components to prevent high-heat components from affecting and damaging other components. If the heating of components is too high, it can be considered to be externally connected to other parts of the hardware and separated from the circuit board to further prevent accidental heating from causing damage to components and circuit boards.
    3. Following the above suggestions, the layout of the PCB should not only ensure functionality and safety but also pay attention to practical layout and aesthetic layout. Except for some components that need special placement for safety, high-voltage components should be far away from the frequently touched position to ensure the safety of users, and other adjustable components, such as switches, etc. It is suggested that these commonly used components can be placed close to the place of use so that it is convenient to operate.
    4. According to Viasion’s PCBA production experience, there is usually a general order in the layout of components. Usually, priority will be given to the design of key components, such as power supplies, switches, etc., and then some high-voltage, high-temperature, and heavy-weight components that need to be supported by auxiliary supports, including chips, etc. Finally, arrange the smallest components, such as small resistors and capacitors.
    5. After the above layout is completed, the final inspection is carried out next. First, check whether the actual size is completely consistent with the size of the drawing. Secondly, check whether all components are set on the PCB by comparing the BOM list. In addition, check whether the layout of components is reasonable to avoid mutual influence and conflict between the layout of components. Check whether the high-voltage components are placed in a reasonable position to avoid safety problems and whether the commonly used equipment is in a position that is easy to operate and convenient to use. Check whether the heat dissipation of the circuit board meets the requirements to avoid overheating, damage to the circuit board and components, or short circuits in use.
    6. The above is about PCB size design and some small tips for component layout. The summary is that the size should be appropriate. If the PCB size is too large size, it will be wasteful. Moreover, components are not safe enough when placed in the board with too small size. Try to ensure functionality and practicality, but also pay attention to the aesthetics of the PCB layout. Secondly, high-level components need to be placed independently away from some sensitive components, and finally pay attention to the design of commonly used components in a convenient position.
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    Regarding the Common Software for PCB Design

    1

    There are many kinds of software used in PCB layout. According to different regions and needs, the commonly used software is also different. Protel series is a beginner-oriented design software, which is relatively simple to use. Its design framework is relatively simple and arbitrary, and there are not many conditions. Relatively, PCBs that are relatively simple in daily work can use this software to complete the design, which is also used by beginners. The second is the Eagle series. The main users of this software are mostly designers in Europe, which is not very difficult. It is a PCB design software suitable for beginners.

    2

    The following are the cadence series and the mentoree series. These two kinds of software are more complex to use, especially cadence. Its framework structure is very complex, and all aspects of its design are set under international standards, which is difficult to get started. But once it is used skillfully, the output products have a certain quality assurance.

    3

    Mentor company has two series, but the most commonly used one is the mentoree series. Compared with the previous three ones, it is also relatively complex. Compared with cadence, its outstanding feature is that its online design function is more powerful, which should be the best for online use and design at present, but it is slightly inferior to cadence in other aspects.

    4

    The use of SMT can adapt to trends such as the development of electronic components, the development of integrated circuits (ICs), and the diversified applications of semiconductor materials.

    5

    Next, take Protel series software as an example to list the general operation steps.

    6

    First, start the Protel series software and enter the editor window. Then set the size of the PCB first, and then put the components in the BOM list on the reasonable position of the PCB to complete the layout, and then connect the components with lines. Finally, adjust the layout rationality of lines and components to prevent conflicts and unreasonable placement. After completion, you can save it, and finally print out the drawing we just designed, so you can use Protel software to complete the design of a PCB.

    Some Points Concerning Different Aspects of PCB Design

    There are also some points to pay attention to in different aspects of circuit board design.
    The silkscreen mainly displays the date, UL, company name, etc. in PCB. These data are helpful for PCB applications and after-sales, etc. Most novice PCB designers will focus too much on the font design and position placement of the silkscreen. The priority setting is too high, and the design looks beautiful and generous. However, after the actual operation, they will find that the size and position of the silkscreen are unreasonable, which will conflict with the position of the components. Either they are covered by components, or the characters are too large, which will extend to the welding area. The final character is neither complete nor beautiful. Therefore, when designing the silkscreen layer, the priority setting should not be too high. Try to find a suitable location for imitation after the core components and circuit layout, to make it beautiful and reasonable.

    Pad is very important for the application of shape in the design of PCB. It is not only the shape in the software library, but also the shape needs to be designed and drawn up by yourself in case of special circumstances. There is no doubt that the pad is a crucial link. When many designers use it, they mostly choose conventional circular pads. There are many considerations about the shape of the pad. Different shapes should deal with different types of components and situations, especially for high-temperature components, which are prone to short circuits due to excessive current.

    According to Viasion's many years of PCBA experience, usually, skilled employees in the industry will use teardrop-shaped pads to target these special and important components. The effect is very good, which can prevent the short circuit caused by excessive current or affect other nearby components. In addition, when selecting the shape, it is necessary to ensure that the difference with the pad is not too large, otherwise, the product quality will be affected. In addition, when connecting the circuit of components, the transmission effect and use effect of the pad with one long and one short and opposite mirror will be better.

    As we know, a solder mask is indispensable for the welding of components. Therefore, these masks are very important in both production and design and need special attention. Solder mask is usually divided into two sides. The role of welding aid film is the same as its name, which can effectively improve performance during welding. The other is a solder mask, which is just the opposite of the former. Generally speaking, non-pad places will be coated with a layer to avoid accidentally getting stained with tin. These two kinds of membranes together form a solder mask, which complements each other.

    The Main Process of PCB Design

    I will use the RF PCB designed by Protel as an example to explain the main process of design.

    At present, RF PCB is widely used in our daily life, such as mobile phones, pagers, and so on. As we can see, their size is usually very small, which makes the design more difficult, and the design of the PCB is crucial to the performance of the final product. Small equipment means that the size of the PCB is also very small. The layout of components is very strict because the operable space is very small. If the layout of components is not reasonable, the whole PCB will not work normally. Therefore, next, we will try our best to maximize the performance of PCB in the case of compatibility by analyzing the layout of components and circuits
    The first is the material selection of PCB. Because the RF PCB we designed belongs to the high-frequency circuit, we need to clearly understand what is our primary consideration. The performance parameters of different plates vary greatly. For RF PCB, we first choose the plate with small dielectric constant tolerance for application.
    Now we will enter the design stage. Our example software is Protel, which is also a commonly used design software. First, establish a database file and put in the BOM list of components and the circuit schematic diagram of the final product. Then enter the schematic design. First, you need to import all the components in the BOM list into the database, and then connect all the components according to the circuit schematic of the product.
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    Then enter the PCB board design part, the first is the size problem. Specifically, it should be designed according to the shell of the finished product, and design a reasonable size and shape according to the size of the PCB placed in the embedded part of the finished shell. After planning the size and shape, use the “place track” pointer in Protel to draw. Then the points and holes are determined according to st, such as positioning holes, etc. The first is the production of components. According to the shape and characteristics of the components, the pad with the corresponding shape and size can be made, edited, and stored in the database.
    After the above steps are completed, the general preparations have been completed, including the PCB circuit, size, shape, components, and pads. Then we will enter the layout and wiring stage. Before that, we need to check the previous steps, including PCB lines, whether the packaging of components matches, etc. These inspection steps are also crucial. Usually, we will check the software before the manual inspection. If there is no problem after the inspection, you can go to the next step. First, file the documents.
    Next is the most important and noteworthy part, the layout of components. Because components will affect solder joints, whether the layout of components is reasonable is directly related to the quality of the final product, so special attention is needed. Moreover, due to the small operating space of RF PCB and the high density of components, it is easy to interfere with each other. Therefore, the layout of components is also related to the performance of the final product. As mentioned before, to reduce the interference between components, we need to keep a certain distance between components as far as possible.
    In addition, we can avoid welding problems by arranging the arrangement direction of components, such as unifying the arrangement direction of components. In addition, in the layout, we also need to pay attention to the first-order problem. Due to the small operable space, we should prioritize the layout of large components first, and then arrange small components.
    Moreover, pay attention to the direction of the interface to avoid the reverse direction of the interface layout and the failure of docking after the layout is completed. High and low signal components should be separated, and high and low-temperature components should also be separated to prevent mutual interference and other factors. Lay out according to the compatibility of components, and try to avoid their interference sources.
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    After completing the layout of components, the layout of lines comes next. Try to choose a low-density line layout, and use wide lines in the multi-component part. If the wiring is unreasonable, there will be mutual interference between components and circuits, which will affect the final quality. In addition, try to ensure that the directions of all circuits are consistent to reduce interference. To avoid short circuits, irrelevant components should not be handed over as much as possible.
    Due to the inherent impedance of the ground wire, most interference sources come from the ground wire, so it needs to be reasonably arranged. To sum up, it is divided into different modules according to different functions. Different modules arrange the line summary and finally summarize it to the general ground wire. Divide the digital area and analog area through the ground wire, and finally summarize them on the power line. Reduce the signal loop area.
    After completing the layout of components and circuits, it is completed.

    Types of PCB Design

    The classification of PCB board design is not clearly defined. There are generally three types as follows.
    • The design of the single-sided PCB
    • The design of the double-sided PCB
    • The design of the multi-layer PCB

    Summary

    With the increasing development of science and technology, PCB has evolved into more and more product types and so on. Different products have their special places, as well as their suitable plates and design characteristics, etc. Therefore, each different product type needs our in-depth understanding and research.

    Why Choose Us?

    Founded in 2007, Viasion is a PCB&PCBA manufacturer in Shenzhen, China. Viasion has a team of experienced and skilled professionals with a high degree of dedication and persistence to provide our customers with high-quality PCB products and solutions for technical problems. Our advantages will impress you to consider cooperating with us

    1

    Viasion is equipped with advanced production facilities, testing equipment, and instruments, and also equipped with complete sewage treatment facilities for environmental protection. The entire manufacturing staff team has rich experience and a rigorous attitude toward work.

    2

    Viasion uses high-quality raw materials to produce products, strictly controls quality, and strictly follows the ISO9001 quality control system. The quality is strictly controlled from the supplied material to the finished product so that the product quality is reliably guaranteed.

    3

    We always insist on strictly implementing the production requirements of our customers to make products that satisfy them. We also establish a complete and humanized after-sales management system to make our customers feel sincere and secure. As a result, our company has gained the praise of our customers and 99% of our customers are satisfied with Viasion’s products and services.

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    Frequently Asked Questions

    The following layout requirements for PCB components should be taken into consideration.
    High, medium, and low-speed logic circuits should be arranged in different areas on the PCB.
    The circuit should be arranged in such a way that the signal line length is minimized.
    Ensure that there are no excessively long parallel signal lines between adjacent boards, between adjacent layers of the same board, or between adjacent routing on the same layer.
    EMI filter should be as close as possible to the EMI source and placed on the same printed circuit board.
    DC/DC converters, switching elements, and rectifiers should be placed as close to the transformer as possible to minimize their wire length.
    Place voltage-regulating components and filter capacitors as close as possible to the rectifier diode.
    Noise-sensitive routing should not be parallel to high current, and high-speed switching lines.

    In general, the basic process of PCB design is as follows: pre-preparation → designing the structure of PCB →the layout of PCB→ routing→ routing optimization and silkscreen → the DRC check and the structure check → outputting PDF file

    In general, the services PCB design companies can offer include PCB design (or flex board design), high-speed backplane design, circuit simulation, EMC design, PCB design technology training, schematic component library design, PCB package library design, and the technology consulting of PCB processing and inspection, etc.
     

    When the company’s design team cannot meet the demands of the design schedule and the quality of the design, it is useful to use a PCB design company.
    Using a PCB design company shortens the time to develop products and get them to market.
    For cost reasons, most small and medium-sized companies do not hire or just hire a few full-time PCB design engineers. These companies do not have many projects, and recruiting 1-2 full-time PCB design engineers is a waste of resources. In this case, it is more cost-effective and efficient for them to choose a PCB design company.

    Know more about the strength and backgrounds of a PCB design company.
    Focus on the quality and effect of the design.
    Choose a PCB design company with high professionalism and a good service attitude.
    Be sure to choose a company that can meet your needs, taking into account cost-effectiveness.

    The following are some special considerations for PCB design.
    Avoid high-frequency interference: Minimize interference from high-frequency signal electromagnetic fields, i.e., crosstalk.
    Solve the problem of signal integrity: Basically, it is the problem of impedance matching. Factors affecting impedance matching include the signal source architecture and output impedance, the characteristic impedance of the routing, the characteristics of the load side, and the topology of the routing.
    Implement differential wiring: There are two points to note regarding the wiring of differential pairs. One is that the length of the two lines should be as long as possible, and the other is that the spacing between the two lines (determined by the differential impedance) should be kept the same, i.e., parallel.
    Matching resistor between the differential pairs at the receiver: Usually, a matching resistor is added between the differential pairs at the receiver, and its value should be equal to the value of the differential impedance for better signal quality.
    The wiring of the differential pair should be closely parallel: The wiring of the differential pair should be properly closed and parallel. The proper proximity is because that spacing affects the value of the differential impedance, which is an important parameter for designing differential pairs. Parallelism is also required because the consistency of the differential impedance is maintained.
     

    Any type of PCB can be designed. Without being designed, PCBs can not be manufactured.

    The following summarizes the common mistakes in PCB design.
    Characters designed to be too small cause difficulties in silkscreen. Characters designed to be too large make characters overlap each other and difficult to distinguish.
    The design does not conform to conventionality. For example, the component side is designed on the bottom layer while the solder side is designed on the top layer, causing inconvenience.
    Some useless wiring was done on some graphics layers. For instance, a 4-layer PCB was designed with more than five layers of circuits, which caused misunderstanding.
    Using filler blocks to draw pads in the PCB design can pass the DRC check, but is not conducive to PCBA processing, resulting in the difficulty of soldering components.