Electronic Circuit Design is a challenging task and needs great skills from the user. It needs to know about various concepts to design an electronic circuit. Designing a PCB is like playing a game of chess. Some limitations force you to think ahead, just like there are pieces on the board you must use to move forward. Keep these things in mind before beginning to ensure you don't run out of space or power and select the correct components.
What Is A PCB?
PCBs, or printed circuit boards, are the foundation of nearly every electronic device worldwide. They're used in everything from cell phones and computers to cars, aircraft, and medical devices. PCBs are flat panels of plastic-coated fiberglass that are etched with copper conductors. These conductors connect components so they can communicate with one another.
The Different Methods For Making PCB
There are many different methods to make PCBs. The most common ones are:
1. Iron On Glossy Paper Method
This is one of the most popular methods for making PCBs at home. It's easy to follow and has been around for a long time. This method can make simple boards with only a few components. The disadvantage is that it's not durable and ideal for complex projects.
2. Circuit By Hand On PCB
This more advanced technique requires some skill and patience, but the results are worth it. You'll need a good printer, an etching solution, and essential tools like tweezers, files, and solder wick. This technique works best when you have just a few components on your board or make something simple like an audio output circuit or an LED matrix display driver circuit. It's also great if you want to make multiple copies of your design because it doesn't require much investment in materials or equipment compared to other methods described here.
3. Laser Cutting Edge Etching
This method uses lasers to cut out shapes at high speeds with great precision and accuracy. The laser beam will cut through the material in one direction only. Hence, it is essential not to have any horizontal or vertical surfaces that need cutting, as they would be impossible to achieve with this method alone.
Basic PCB Design Steps
From the moment you realize you need a PCB through final manufacturing, PCB design is involved in every stage of printed circuit board manufacture. There are six phases in the fundamental design process;
1. Concept
The next stage is to choose the final concept for the board after establishing the necessity for a PCB. In this early stage, the features, connections, placement, and approximate dimensions of the PCB are defined, along with the functions it will have and carry out. Also, consider any additional environmental problems and the general temperature range the board will work in.
2. Schematic
The circuit diagram is then drawn based on the chosen design. The electrical components of the board are shown in this figure with all the information necessary for proper operation, as well as specifics such as component names, values, ratings, and manufacturer part numbers.
Your bill of materials will be created as you create your schematic. All the component information you require for your PCB is in this BOM. These two documents must always be current.
3. A Block Diagram For A Board
The next step is to finish a board-level block diagram, a design showing the PCB's final dimensions. Mark the regions that belong to each block and the parts of the components that are connected for electrical or practical reasons. Your traces may be kept brief if related details are kept together.
4. Component Positioning
Component placement, which comes next, establishes where each part will go on the board. You may frequently go through numerous iterations of component location refinement.
5. First-Pass Routing
Next, choose the circuit's routing and priority for that routing.
6. Examining
After completing the design, you should run several tests to ensure it satisfies your requirements. If so, the design is finished. If not, you will return to the stages where changes are necessary.
Things Every PCB Designer Must Know Before Designing The PCB Layout
The PCB designer must know some crucial things before designing the layout. Here are some of the critical items every PCB designer must know before designing the PCB layout:
1. Sizing Traces
Trace sizing is probably one of the most critical aspects of designing a PCB layout. If you have too thin traces or pads, they may not handle the current being drawn by the components on your board. If there are too many vias in a trace, this can also make it weaker and more susceptible to breaking.
2. Make Loops Small
Loop areas are where two traces come together and leave each other again. These areas should be as small as possible so that they do not create unnecessary resistance or inductance in the circuit. You should also try to keep these loops away from sensitive areas like power supply inputs or high-speed signals because they can cause interference with other parts of your design.
3. Decoupling Capacitor Placement
Decoupling capacitors reduce voltage spikes in your circuit by storing charge when there is a sudden change in a current draw or a high-frequency oscillation. You should always place these between power supplies and sensitive circuits because they help protect against these spikes, which could damage your chips if left unchecked.
4. Keep Digital And Noisy Traces Away From Analog Traces
Using a solid ground plane under your digital signals is the best way to do this. This will help keep the noise in the digital section isolated from the analog section. If you don't have a big enough area for a solid ground plane, try to keep everything that needs to be grounded on the same side of the board as your analog components (since they are sensitive to any ground noise).
5. Kelvin Connections
When two copper traces are directly connected, they form a Kelvin connection or short circuit. This can cause an unwanted solder joint and lead to problems like cold solder joints and poor reliability of the PCB. An excellent way to avoid this is to add vias that connect all the layers.
6. The Ground Is Not Ground
Understanding the difference between ground planes and reference planes is essential to avoid common mistakes when designing your PCB layout. Ground planes connect different circuit parts, while reference planes provide a common return path for signals on separate layers.
7. Via Size And Number
The size and number of vias used in your PCB layout will impact its performance and cost-effectiveness of production. You should use vias with a large diameter so that heat can easily dissipate from the board but small enough so they do not weaken it too much or cause weak spots where cracks could form later in its lifetime. The amount of vias that need to be added depends on how many layers your board has.
8. Using PCB As A Heatsink
Using PCB as a heatsink is one of the most common ways to improve the heat dissipation of electronic components. The current trend of using heat sinks is to use a heat pipe or a thin film on the surface of the PCB. This design method can significantly reduce the cost and increase the effectiveness of the thermal contact between the air and the components.
9. Thermal Vias
Thermal vias are small holes drilled in a circuit board that provide an electrical connection between traces or pads on different layers that are not connected by usual means (e.g., traces on different layers). These holes can be filled with conductive paste or solder to establish an electrical connection between two parts of a printed circuit board (PCB) while providing a low resistance path for heat flow away from high-temperature devices such as power transistors and ICs.
10. Distance Between Traces And Mounting Holes
If you are designing a PCB that will be used in a high-heat environment, such as an amplifier, you should keep the distance between mounting holes and traces as large as possible. This will help dissipate heat from the traces to the mounting surface of the PCB when it is screwed down into place. If your design does not have mounting holes, keep traces away from hot areas.
11. Heat Sensitive Components
When placing components on your PCB layout, ensure not to put them directly under a heat source like resistors or diodes. For example, don't put them directly under a power transistor because it will get hot enough to damage them. Also, try not to place them near other components that may get hot such as power capacitors or transformers, since these can also affect their temperature and cause failure in some cases.
Conclusion
Make sure that you follow the steps mentioned above. Making a PCB layout is quite challenging, and without it, you might fail at it. This can cost you time, money, and effort and even damage your reputation. However, if you have made all the mistakes before, you can surely avoid them and make your PCB design process smoother by following the above simple rules.
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