PCB layout is like completing a piece of art. Every step brings together the minds of the producers. The same kind of PCB board, the results of different designers are not the same.
Engineers spend days, weeks, or even months designing these patterns, typically producing something. Wouldn’t you also want to do the same thing? Convert the electrical theories that you have been studying in class to a real physical design!
Seeing this, I believe you want to know some things in the PCB layout process. No doubt, you will have to face a few challenges down this road. But PCB layout is the best part of designing a circuit board.
1、What’s the PCB Layout?
A PCB layout is a broad word used to indicate the several processes needed to design a PCB. You will need to learn Electronics Design Automation EDA – CAD software for this purpose. First, you will design your circuit schematics in software like Altium Designer, Eagle, Proteus, etc.
Then, in the same software, you will manifest the schematic into a PCB layout. Here, at this point, let your creativity run wild and make a convenient and precise PCB layout. You can make traces, mount holes cutouts, and specify component locations, label, and feed-throughs using the CAD layout tool. It will put you on the first step of the ladder leading to a physical PCB layout.
Don’t worry, if you believe that you may not be able to make an acceptable PCB layout. You canjust contact the engineers who are experts in laying out PCBs. We are also experts in making PCB layouts and at cheap rates.
Figure 2 shows the screen of a Professional Engineer’s desktop computer. He has made a very professional PCB layout on his computer.
Image 1: PCB Layout
This section briefly discussed the basics of a PCB layout. In the next chapter, we will give you the six main tips for making a PCB layout.
2、PCB Layout Tips
2.1. The principle of original layout
You will see the option of “auto-router” in almost every PCB design software that you will use. Your instincts will tell you to use it considering it as an easy way for PCB routing. However, we will give you advice to never use it. But why? Just because it is not always precise and symmetrical.
No matter how inexperienced you are; you would always come up with designs better than the auto-router. Nonetheless, if you are stuck at some point, you can take help from it. Further, you can also use it to find bottlenecks and get the completion rating of your placing.
Figure 3 shows a simple circuit schematic that the engineers may need to turn into a PCB layout.
2.2.Original layout direction
Before starting to place the components, you should consult your manufacturer. Listen to any demands he may have regarding the number of layers that they can tackle. Or, if there are any particular requirements for trace spacing and minimum trace widths.
You need to determine the consistency of direction not only for aesthetics but more importantly to balance current.
2.3. The spacing of originals in the layout
Electricity will pass through your copper traces, and it will surely generate heat in doing so. This vital concern can be mitigated by controlling the spacing of the traces. You need to control their width.
Remember it as a general rule: the wider the trace, the less resistance the current encounters when passing through the circuit.
Image 2: PCB Layout
2.4. Avoid using a 90-degree angle
You should avoid using a 90-degree tracing angle, choose 45 degrees, and the horizontal angle is best. Are you wondering why? It will avoid short circuits. You will observe that 90 degrees traces angles may not get fully etched and thus causing short circuits.
2.5. Always create a plane
You should always have a common ground terminal in your circuit schematics. It is important for PCB layout too as it will provide your traces a common reference terminal for measuring voltages. However, you are in trouble if you utilize traces rather than a ground plane for routing.
If it is not a plane, you will find multiple resistance values because of multiple ground terminals on the PCB. It can turn into a nightmare as these resistances will also have their voltage drops. So, always create a separate plane when making the layout of your PCB. Figure 4 illustrates a ground plane in red color.
Image 3: PCB Layout
2.6. Avoid overlapping
Finally, you should at all costs avoid overlapping in PCB layouts. Overlapping PCB layouts can make your entire line more complex and unobstructed.
So, these were the six basic tips for making a PCB layout. Now, in the coming section, we will discuss the three steps of the PCB layout process.
3、The Process of Considering PCB Layout
Although the PCB layout is like a piece of art, you also need a definition of the layout process. We agree that the routing process and component placement depends all upon your creativity. Still, we would suggest you begin in an organized manner.
In this chapter, we will tell you about the organized PCB layout process. This process would not throttle your creativity as it would rather give it a foundation to grow. Everything has limitations, and it is always best to know the boundaries in which you can design.
You should consider following the following three steps:
First step: First turn your schematic into a PCB layout.
Second step: Then, you should add and rotate components to reduce the crossing and length of air wires.
Third step: At this point, you are done with placing components. So, the final step is to adjust the layout size for routing. Figure 5 demonstrates the PCB layout routing.
It is the fundamental information that you need to begin making a PCB layout. In the coming section, we will jump to Electromagnetic Interference EMI with printed circuit boards.
Image 4: PCB Layout Routing
4、PCB Layout – Three Elements of EMI
Look at any typically printed circuit board placed around you. You will see that it has many circuits printed over it. However, these individual circuits may prove to be harmful as each of them may be a source of energy. Are you wondering how that is bad?
It is bad in a way that one circuit’s energy can interact with energies from other devices or circuits. It will result in unwanted noise and will affect each circuit. Further, this phenomenon is known as electromagnetic interference EMI.
You should use technical equipment to locate sources of disturbance and potential sources of disturbance. It will greatly reduce your troubles. You will be able to avoid coupling pathways.
4.1 Three types of coupling
Each circuit is a potential source of energy that can eventually be inadvertently coupled to other circuits or devices. Coupling happens between an antenna and its energy source on a PCB. An antenna may be a copper trace, and an energy source will be an electronic component.
The following are the three coupling situations that you may encounter:
• Conducted coupling: It will happen when the energy source energizes one decent part of the antenna concerning another. For instance, when a signal trace that is capable of being a good antenna part is not routed over a plane and is rather energized concerning the signal return plane.
Image 5: Here, a PCB Trace Has Been Coupled to a Heat Sink
• Electric field coupling: It is the coupling that is driven or energized by voltage. In other words, you call it proportional to the voltage of the source.
Image 6: Here, the Voltage of a Component is Energizing Heat Sink Concerning the Circuit Board
• Magnetic field coupling: It is the coupling that is driven or energized by the current. In other words, you call it proportional to the current of the source.
Image 7: Magnetic Field Coupling
4.2 Sensitive Devices
Here, we will briefly introduce those sensitive devices that can interfere with the PCB layout.
4.2.1. Clock circuit
Synchronous digital clock circuits are usually the most powerful signals on a PCB. Thus, it is common to observe radiated emission peaks at narrow-band. You will also see that these peaks occur at harmonics of the clock frequency.
Figure 8 demonstrates that the harmonics of the 25-MHz clock are dominating the radiated emissions.
Image 8: 25-Hz Clock Signal Harmonics
4.2.2 Digital signal
Many PCB traces do not have clock signals but rather have digital information. This information is in the form of digital signals. These signals are not as cyclic as clock signals, and their randomness leads to wide-band noise.
They do produce radiations like clock signals if they toggle more frequently. Usually, data signals are considered to be less dangerous than clock signals. Still, data traveling at high-speed can generate loads of noise.
4.2.3 Power switch circuit
DC-DC converters and switch-mode power supplies provide various voltage levels by rapidly switching current in a transformer. You will observe that the typical switching frequency is between 10-100 kHz. The spike current produced by this switch couple noise to the devices on the board and the power supply output.
It also produces wide-band noise even though the noise signal is somewhat periodic.
This section briefly introduced the concept of EMI in printed circuit boards. In the next chapter, we will now tell you about the PCB layout services that are provided by our company.
5、PCB Layout Services
Are you looking for companies that provide PCB layout services? If that is the case, this chapter is for you. We will briefly discuss the services provided by firms around the globe. There is no need to fret if you are just a beginner in this field.
5.1 PCB Layout Designers’ Services
If you plan to get PCB layout services, you will make sure that you are getting:
•1.PCB layout services for existing and new printed circuit boards.
•2.Different tests to prevent manufacturing process problems.
•3.Assignment of the electronic devices just the way you may desire（Height restrictions)
You can as well get a finished PCB product just from your circuit schematics. Furthermore, PCB layout designers will also try their best to provide you with the following services:
1.Provide basic design information or provide schematics in any format. They will then transform the design into a CAD format (electronic).
2.Design rules will be obeyed when designing the schematics.
3.Personalized footprint design to fulfill your requirements（Controlled impedance and SI trace width and spacing）
•4.Complete part pricing and BOM for every design.
•5.Complicated PCB shapes can be developed; Rigid/Flex PCBs.
•6.Fabrication Assembly, Drawing, and Gerber files to fulfill requirements for manufacturing.
5.2 PCB Layout Designers’ Deliverables
Moreover, you will also get the following deliverables when working with these designers:
PCB layer stack diagrams, Complete Schematics, All 3D PDF Files, Fabrication files (Gerber X2, Gerber Extended, IPC-2581 available upon request, ODB++), All Bill of Materials (BOM) list, Fabrication specifications (Drill Tables, Layer Stacks, and Drawings, etc.), Rout and Drill files, Pick and Place files and Assembly diagrams.
PCB designers can also provide you with drawing packages and full Geber files if:
You have an existing design that needs to be altered, updated, or enhanced for cheap assembly. You need a PCB layout of your circuit schematic. You require an original PCB design.
Moreover, all the companies will use the software that you may desire. If you have any favorite software, you can simply ask your designer to use it. This way you will feel more comfortable with your PCB layout designs. Their engineers are experts in Eagle, Altium, Cadence Allegro, CADSoft, and many others.
This article is about the tip of the iceberg in the PCB layout, and there is more to learn. You would have heard that there is always room for improvement. So, we can learn and explore together and guide readers to follow us.
If you have any further queries or want to place an order simply contact us. Once you are satisfied with your PCB layout, you can contact us PCB assembly and manufacturing. For order, you can directly place it on our website. Our team will be more than happy to help you out in any way. We are always here for you.