PCB Layout Design Process and Guidelines
Imagine living in a world where there were no technological advancements such as the cell phone, computer, television, radio, vehicle, or airline. This would be very difficult for most of us to do. Without the printed circuit board (PCB), it is not feasible to attach electronic components in certain positions on devices, nor is it possible to connect the terminals of the components in a reliable and arranged manner. The truth is that most devices would be rendered inoperable in the absence of a suitable PCB layout. The development of a PCB layout is analogous to the completion of a work of art. To create something really one of a kind, it might take engineers days, weeks, or even months to design these patterns. On the other hand, you don’t need to be an engineer to design an accurate PCB layout; you can do it yourself.
This article was written specifically for you in case you have no idea how to get started. You will have a better understanding of a few topics regarding the process of PCB layout because of reading this post. Beginning the process of constructing a PCB layout may first appear to be intimidating; however, if you start with simple designs and give yourself plenty of time to practice, you will quickly learn that you will soon become an expert.
Table of Contents
1. What is PCB Layout?
A PCB layout is the arrangement of various components on a printed circuit board (PCB). It is a crucial step in the design of electronic circuits, as it determines how the components will be physically connected and how they will interact with one another.
In a PCB layout, components such as resistors, capacitors, transistors, and integrated circuits are placed on the PCB in a specific pattern to create the desired circuit. The layout also includes the routing of the traces, which are the conductive pathways that connect the components and allow electricity to flow through the circuit.
The layout of a PCB is typically created using computer-aided design (CAD) software, which allows the designer to position the components on the PCB, specify the connections between them, and automatically generate the routing for the traces. The resulting layout is then used to create a physical PCB through a process called PCB fabrication.
Overall, the PCB layout is an important part of the design process for electronic circuits and plays a crucial role in ensuring that the circuit functions correctly and reliably.
2. Process of PCB Layout Design
From the time you realize you need a PCB until the moment you ship the completed product, PCB layout design is an integral part of the printed circuit board manufacturing process. There are six stages involved in the fundamental PCB layout design process.
2.1 INITIAL CONCEPT
The following stage, which comes after confirming that a PCB is required, is to settle on a definitive concept for the board. During this first step, the functions that the PCB will have and execute, its characteristics, its interface with other circuits, its placement in the final product, and its approximate dimensions will all be defined. In addition to this, you should think about the temperature range that the board will function in approximately, as well as any other environmental considerations.
2.2 Defining Schematics
The following step is drawing the circuit diagram or schematic based on the final concept that was chosen. This diagram contains all the information required for the electrical components of the board to work correctly. Included in this diagram are particulars such as the names of the components, their values, their ratings, and the manufacturer part numbers.
You will generate the bill of materials concurrently with the creation of the schematic you will be using. This bill of materials (BOM) provides details on all the components that must be included on your PCB. Always make sure that these two papers have the most recent information.
2.3 Component Placement
The last stage PCB Layout design is called component placement, and it involves deciding where on the board you will put each individual part. In many cases, you might have to go through numerous iterations of tweaking the location of components. Correct orientation and suitable location selection are key considerations in this stage.
2.4 Routing and Testing
Next, determine the routing and the routing priority for the circuit. After you have finished the design, you should put it through a battery of testing to confirm that it satisfies all your requirements. If it does, then the design process is finished. If this is not the case, you will be forced to restart the phases during which you are required to make corrections.
3. Design Considerations for PCB Layout
When it comes to the layout and design of PCBs, there are a lot of things to think about. Certain factors should be considered throughout the entirety of the procedure, while others are relevant just to certain phases. The following are seven important considerations to keep in mind:
3.1 PCB Board and Number of Layer Constrains
The restrictions that are related with the bare board should be the very first ones that you investigate. The dimensions of the board as well as its contours are examples of these fundamental limitations.
You will need to make sure that there is sufficient space on the board for the circuit. The size of the final product, the functionality that the board must give, and several other criteria all contribute to the determination of how big the board ought to be. The size of electronic items and the circuit boards that they integrate may be expected to continue their downward trend. Make an educated guess about the dimensions of the board before beginning the design process. If you do not have sufficient room for all the functionality that is necessary with a design that is more basic, you may be obliged to employ a design that is either multilayer or high-density interconnect (HDI).
The typical PCB takes the form of a rectangle. This continues to be, by a significant margin, the most popular form for PCBs. However, it is possible to construct boards in a variety of alternative formats. PCB designers typically use this due of size restrictions or because the board will be used in goods with an irregular form.
Another essential aspect to consider is the number of layers that will be required, the number of which will be determined by the power levels and the intricacy of the design. It is in your best interest to determine how many you require early in the process of designing the plan. It’s possible that adding additional layers could drive up production expenses but doing so will let you incorporate more tracks. It’s possible that more complicated boards with more extensive capabilities will require this.
When making layer transitions for high-current routes, always be sure to use a minimum of two vias. The utilisation of numerous vias at layer transitions results in an increase in reliability, an improvement in thermal conductivity, and a reduction in both inductive and resistive losses.
3.2 Manufacturability & Installation Constrains
You should also think about the manufacturing procedures that you want to use to create the board that you want to make. The limitations and restrictions that come with various procedures vary from one another. On the circuit board, you will need to make use of reference holes or points that are compatible with the manufacturing process. Always check to see that the holes are free of any components.
Additionally, take in mind the technique of installing the board. It’s possible that certain strategies will need you to leave different parts of the board unexplored. Utilizing several types of technology, such as through-hole and surface mount components, might result in a rise in the price of your boards; nonetheless, this approach may be essential in some circumstances. Always be sure to check with your fabricator to ensure that they can build the sort of board you want by asking them directly. Some companies, for example, might not be able to build circuit boards with a flexible design or with a design that contains several layers.
3.3 Component Organization
By systematically arranging your components in a way that makes sense, you may cut down on the number of steps that are necessary for assembly, which will both increase your productivity and lower your expenses. Your goal should be to place all of your surface mount components on one side of the board and all of your through-hole components on the top side of the board.
If possible, avoid placing components on the solder side of the printed circuit board (PCB) that will sit behind plated through-hole components. When you are installing components, you should try to align those that are analogous to one another in the same direction. The process of soldering will become more effective because of this, and it will also assist to reduce the number of errors that occur.
3.4 Tracing Considerations
The best practises for PCB layout dictate that you always insert short, straight traces between components wherever it is practicable; nevertheless, it is conceivable that this will not always be viable in bigger boards. If the location of your components requires horizontal traces to be routed on one side of the board, you should always route the traces vertically on the other side of the board. This is one of the many key guidelines for the design of a 2-layer PCB board.
The more layers you have in your stack up, the more complicated the rules and principles for designing printed circuit boards and laying out PCBs will become. If you don’t partition each signal layer with a reference plane, your routing strategy will need alternating horizontal and vertical traces in alternating layers. You will need to adhere to PCB board design standards that are specific to your application if you are designing particularly complex boards for specialised uses. This is because many of the generally promoted best practises for PCB design may no longer apply in these cases.
4. Power, Ground & Signal Trace Considerations
After the components have been installed, the next step is to route the power, ground, and signal traces such that the path taken by the signals is uncluttered and free of interference. At this point in the process of laying up your document, it is important to bear in mind the following guidelines:
Power and ground are often located on separate internal levels, as this is the most common configuration. It’s possible that doing this on a board with two layers won’t be as straightforward, in which case you’ll want to put a huge ground plane on one of the layers, and then route signals and power traces on the other layer. Instead of attempting to route ground traces, you should make use of ground planes when working with circuit board stackups that have four layers or greater. It is advised that components that require direct connections to power utilised common rails for each supply if a power plane is not used; ensure that the traces are large enough (100 mils is adequate for 5 to 10 A); and do not daisy chain power lines from one component to the next.
There are certain guidelines that indicate the positioning of plane layers need to be symmetrical, although this is not a necessary requirement for production. It is possible that this will be necessary for large boards to lessen the likelihood of warping, but this will not be an issue for smaller boards. Before you worry about maintaining perfect symmetry in the PCB stack up, you need make sure that you have access to power and ground and that all traces have a strong return path coupling to the ground plane that is the closest to them.
5. ele Technology Co. the Leading PCB Manufacturer
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