The manufacturing process of PCB or PCBA is considered one of the most complex processes. It consists of three main stages; design, build, and test. Prototyping comes in the very first level of creating new boards. This process requires various iterative cycles of DBT or design-build-test, which ends with a final quality product.
The process remains the same throughout the process while the design of the board undergoes constant changes. Sometimes, changing the schematic in a PCB design is necessary for the designing phase. While, sometimes, it is not required.
Do You Really Need A Layout From Your Schematic?
Sometimes to answer one question, we have to add more questions with answers to understand and clarify the answer appropriately.
What Is A PCB Layout From Your Schematic?
A printed circuit board schematic refers to a graphical and geometrical representation of electrical components with their connections for the design of an electrical PCB.
What Does A PCB Layout From Your Schematic Contain?
The schematic of the PCB contains labels, symbols, and signs for all essential factors to describe the functions of a PCB design. This includes all active and passive electrical components, nodes, nets, reference indicators, terminals, ground connections, and connectors.
How Is A PCB Layout From Your Schematic Used?
Schematics considers a type of canvas to create a design of an electrical circuit. It creates the design, reviews it, and evaluates it. This whole process ensures that it follows all the connections before changing the schematic into a design PCB for manufacturing.
However, as the answer depicts, the schematic serves as the initial point for designing an electrical circuit. In most cases, a schematic also serves as a basic template for designing a board.
Designing Your Board Layout From Your Schematic
In the past, designers actually made schematics and circuit designs with their hands and were considered highly skilled. However, today we have various tools like ECAD, which simplifies the whole process of designing PCB. At the same time, these tools offer automatic conversion of a schematic into a PCB layout. So, before conversion, you need to complete a few steps to create a design for the manufacturing process.
PCB Layout From Your Schematic Steps
1. Choose A Board Size
Most ECAD software contains the default size of the board with thickness and area, which allows you to choose accordingly. However, always double-check with the contract manufacturer before choosing any size of the board because the board may lead to material waste and eventually affects the manufacturing cost.
2. Create The Stackup
After selecting the dimension of the board, determine the layer count, number, and materials of the board.
3. Arrange Your Components
After selecting everything, then comes the placement of electrical components over the board surface. Make sure to follow the rules of clearance and spacing to ensure the manufacturing process of the board.
4. Route the Traces
The routing of traces is considered the most complex part of the PCB design. Designers face many challenges, especially in multilayer boards along with several PTHs that vertically carry signals from and to ground planes and internal signals. Make sure to follow proper clearance and spacing.
5. Check For Errors
Once you complete the design of the PCB, do not send it right away for manufacturing. First, check for any types of errors in the design. Perform an analysis of DRC which ensures that the design follows all the necessary rules or not. However, these rules must be set up on the basis of the DFM and CM’s guidelines to ensure manufacturability.
All these significant steps ensure the creation of high-quality PCB design. Designing PCBAs does not consider a very simple process. However, the difficulty level and time required to reach a proper design depends on the types of ECAD software you utilize for turning the schematic into the design PCB.
Transition Your Design Layout From Your Schematic
To ensure a clean design database to use, you have to ensure that you have a clean and complete schematic. However, you have to follow the steps before converting the schematic into the layout.
· A Completed Schematic
This, however, does not imply that you cannot change the schematic during the layout. As ECOs consider their life. Therefore, this literally implies that the schematic must reach a stage where future conversion of the schematic would not change the layout intent.
· Production Parts
Ensure update all developmental and temporary parts on a schematic before sending it to the layout. If you cannot do that, then ensure to leave space to adjust any circuit board footprint alteration that may get done in the future.
· Duplicate Circuitry
Search for unwanted circuitry developed during the copy/paste function and delete it, as you may never want to place components on the board where they do not belong.
· Text
Ensure that placement and correction of all the essential identification text, net names, reference designators, and design notes.
Working With Tools
Once you complete the schematic and test it accordingly, move on to the next part to place information in the database of the layout. However, to do that, you have to follow some steps to achieve the conversion of schematic to layout.
· PCB Footprints
First, you need data on PCB footprints for successfully generating the connectivity netlist for the database of the layout. However, if you developed a schematic with online symbols of components, then the footprint data of PCB has already been downloaded with these symbols. Whereas, if you use symbols in the schematic from other data sources, then ensure that all those symbols point toward the right footprint. In addition to this, you also have to ensure that the files of that footprint must have access to the database of PCB. If not, then you have to put them in your design, or else you have to make them yourself.
· Create The Netlist
The process of creating the netlist comes in different forms in different schematic software, but all follow the same process. After arranging all the settings for the specific design and schematic database, start the process of creating the netlist of the PCB from a schematic. However, the netlist typically includes essential data like information, net and component properties, rules of design, and constraints of high speeds. In addition to this, it also includes the footprint and designator names of the component.
· Create The PCB Layout Database
However, if you don’t have a database of PCB design, then you have to make it. You have to follow just simple steps to create the database of the PCB design. First, create the layer stack up and outline the board. Drag in PCB footprints with other essential design objects such as Via. Then set up the necessary parameters and some additional rules of board design.
· Import The Netlist
You have the database of the PCB design, now import that Netlist. However, you already know that different software works with different mechanisms. But they all follow the same process of putting the connectivity netlist in the database of PCB layout.
· Check For Errors
Even though you check and set up the schematic well, you may still face unexpected problems in the database. A typical example of such a problem refers to a symbol of the schematic that has a different pin number on the schematic and physical footprint. This typically happens for unutilized pins on electrical components, which does not affect the final process of the PCB. Therefore, to avoid continuous warnings coming out during the designing process of PCB, make sure to correct the problem now.
Until now, you have successfully converted the schematic connectivity into a PCB layout. You can easily move forward with your manufacturing process without further ado.
Use The Most Effective Tools
The layout of a PCB contains several steps, and converting the schematic to a layout considers the very first step among them. Other than placement and routing of the components, it also includes the management of the power distribution system of a board and setting up rules to ensure FCB manufacturing, assembly, and analysis. Furthermore, you may have to work with high-speed constraints design; therefore, you need to send back the layout to the schematic for an update according to the design.
In order to understand how Cadence works in the process of designing PCB, you have to understand some other topics first. This includes the routing, RF design, DFM tips, high-speed design of the PCB, and PDN design. All of these help you understand better how to create a successful schematic and how to convert it into a successful design for the successful manufacturing process of a PCB.
However, there are several online PCB design tools. You can also utilize Allegro from Cadence. It contains all the features that help you make a successful PCB design. It does not help in creating schematics and design, but it allows you access to signal and power integrity tools, circuit simulation, and much more.
