What are the basic steps of a PCB design?

The design process comprises various stages.Each stage has it's own defined processes and checklists.To design a successful PCB,It is essential to follow the processes and check through the design checklist at everymilestone.

The design process of a PCB will essentially begin by creating a schematic.This schematic is then develop into a PCB layout using CAD software.
It is essential to have a solid grasp of the steps involved in designing a circuit board layout.
The first step involved in PCB design is to draw your concept block diagram on paper.This block diagram is then developed into schematic designs using a PCB layout tool.A schematic consists of component symbols and net connections between the symbols.These nets will become traces on the circuit board.
The next design stage is hte pre-layout stage;in this stage,The BOM from the schematic is validated for long lead time components and obsolete components.During the validation process,the manufacturing part numbers(MPN) and vendor part numbers are verified.During this stage,the stack-up design is also completed.

The PCB layout stage is next.In this stage,The board parameter settings,board outline,component placement,routing,and production document generation are completed.

Step 1:PCB schematic creation
A schematic diagram is a representation of the elements of a system using abstract and graphic symbols.In this phase,The design is entered into the schematic tool(Altium,Allegro,ect).A schematic shows the components used in the design and how they are connected.If the design uses a hierarchical schematic,where numerous functional schematics are interrelated,the schematic defines the relationships between groups of components in different schematics.An example of the schematic diagram is shown below.


Schematic generation is creating a logical representation of the electronic circuit.When you generate a schematic,you are connecting a collection of symbols(components)in a unique way,creating your unique electronic product.
1.Schematic symbol generation
The Altium Designer symbol generation tool can be accessed by choosing the Tools-Symbol Wizard command from the main menu.The symbol generation process involves drawing the body of the component,adding pins and pin numbers,defining hte reference designators,and assigning a footprint.
2.Schematic symbol placement
The body of the symbol is created by placing graphical design objects in the schematic library editor workspace.Altium Desiner includes a variety of closed symbol shapes,including rectangles,pentagons,ellipses,and triangles ect.
3.Pin numbering
Pins define the connection points on the component for the incoming and outgoing signals.Pin numbering is made to ensure the connections shown in the schematic,end up connected properly by copper on the PCB.It is the component pins that give the component its electrical properties and define connection points on the component for directing signals in and out.A pin is placed to represent each pin on the actual physical component.

Pins can be placed in a schematic library document using one of the following steps:
--Click Place-Pin in the main menu
--Symbol options dialog will appear.Use this dialog to define the symbol height and width,the length of its pins,and a style for it's pins about the ports on the source sheet,and click ok.
4.Reference designators
Reference designators mainly include category,value,manufacturer,manufacturer part number,and supplier.It is recommended that every symbol on your circuit have its unique designator so that every part is easily identifiable.For example,every resistor should follow a consistent naming sequence of R1,R2,R3,ect.
5.Assigning a footprint
The footprint gives an idea of the actual size of the component.For example,When we put a component on the sand,it will leave it's impression there.This imprint is it's actual physical size.Some components come in standard packages,and the footprints are easy to find.In some cases,we may have to create the footprint manually,Below are the steps to creat a footprint in Altium Designer.
--Creat the pads
--Key-in component height and area.
--Provide the silk-screen information.
--Save the footprint.
6.Connecting the symbols
It is very important for a PCB designer to clearly show how the components are interconnected in the schematic.First,whenever you have two wires that form a junction and share an electrical connection,that intersection needs to have a junction dot.This is standard practice in every schematic design.If you have a pair of intersecting wires that are not electrically connected and are just overlapping,then you will not need a dot.
7.Link the footprints to the symbols
The components'footprints are shown on the schematic diagram when you transfer the schematic information to the PCB layout.
8.Generate the netlist
Netlist in any PCB designing software contains information on the component name and the pad of that component which is connected.Netlist also assigns numbers to the connections in serial order.The Netlist manager dialog is used to control and manage the netlist of the board.Nets can be edited,added,or deleted as the requirements.The pins(or pads)of the components in the nets can also be edited.
9.Perform a netlst check
The export netlist option is used to export the netlist of the PCB to hte current document.Once the command is launched,a netlist document with an extension.'Net' is saved in the same folder where the circuit board design document is saved.A net-by-net verification in the schematic should be carried out(whether all the nets are connected as intended).
10.Generate BOM
The bill of materials(BOM),is simply a list of required materials for manufacturing a printed circuit board.In Altium Designer,Bom can be generated by choosing the options Report-Bill of Materials from the PCB schematic.
It is always recommended to carry out a PCB layout review after every step/sub-step to ensure an error-free design.

Step 2:Pre-layout stage
In the pre-layout stage,we initiate the design of the stack-up,ensure that the BOM is verified for all parts,and verify that the parts are active and not obsolete.
1.Bom validation
The BOM is simply a list of required PCB materials for manufacturing a printed circuit board,The first step in the pre-layout stage is to ensure that all the materials required for your design are available.
During the BOM validation,the following is verified:
--Manufacturing part numbers(MPN)are correct.
--Vendor part numbers(VPN) are correct.
--The quantity of the parts is correct.
--Designators match the schematic.
--DNI(do not install) components are marked in BOM
2.Design the stack-up with the help of contract manufacturer(CM)
Designers need to have the details of the stack-up before starting the layout design.Designers always design the stack-up,but they are usaully assisted by the fab house in getting the right stack-up arrangement.

The parameters required for the planner include:
*The materail of the PCB(FR4,I-Speed,Rogers,ect.)depends on the frequency reqrements and environment(for example,high temperature)
*Number of layers-signal layers and power layers.
*Impedances required like 50Ω single-ended,90Ω differential,or 100Ω differential.
*The thickness of the copper(1/2 & 1 & 2 ounces)

Step 3:PCB layout stage
The PCB layout stage includes setting up the design tool,board outline,netlist import,component placement,routing,silkscreen clean up,DRC check,and generating documents for production(Gerbers,netlist,ect.)
1.Setting up the stack-up
The board layout is started by setting the stack-up and design rules.The stack-up is set up in the tool using the layer stackup manager tool.The stack-up design geneated by the stack-up tool from the PCB manufacturer is used as a reference to set up the stack-up in the layout tool.Steps to design your PCB stack-up:
*A single-layer stack-up,by default,is defined when a new board is created.
*The currently selected stack is duplicated if you click the add stack button.Once the new stack is added,the name and the properties can be changed in the stack properties tab of the dialog box.
*Click hte Add layer button for a separate solder mask and over layers.
*The order of the stack-up can be changed using the Move left and Move Right buttons that are present at the bottom right of the stack-up tab.
*For flexible PCBs,the flex stack-up should have it's Flex option enabled.Flex bending is defined by placing a Bending Line across the flex region(Design-Board Shape menu)
2.Set the PCB design rules
3.Draw the PCB outline
4.Component placement
5.Route the board nets
6.Perform a design rule check(DRC)
7.Complete PCB fab/assembly notes

Step 4:Generate the production files
1.Gerbers and other production files
2.Perform a DFM check