Synonyms

PCB, printed circuit board, printed wiring board, etched wiring board. PCB

PCB general Description

A printed circuit board consists of conductive traces that are glued on a non-conductive substrate. Substrate is an insulator while traces are the conductive paths. These traces interconnect the electronic components on the board. Thus defining a circuit (mostly an integrated circuit) for the desired system or embedded system. Electrical or electronics engineer designs the circuit according to the specifications. Then it is the lay out specialist who designs the PCB for that circuit.

PCB Design

Before designing the Printed Circuit Board Physically the designers simulate the circuit that is to be implemented using PCB. Then generate the layout to define area and other factors depending on the circuit. The process of generating lay out is carried out by software tools known as EDA (electronic design automation). EDA tools allow the designer to carefully observe the design information. The designer can edit the design if finds any error or updating. Here are the steps an EDA tool perform in such context:

Net list

A net list is the list of component pins and the connections of the pins with each other in the design. The schematic capture program in the EDA Software defines the net list.

Defining Position

Next step is to define the position of the device on the Printed Circuit Board. This is physical position of the device on the PCB. Different EDA tools use different methods. Such as some use letters on rows and columns, some use scale, etc. after deciding the position the EDA software generates device list. Device list along with net list is merged and send to the PCB layout editor.

Libraries

Each device defined in the design includes a library. The library carries the information about device. The information is like device size, pin's, pad and drill hole, etc.

Routing

The routing defines the best possible interconnect paths in the design. For example assigning the ground wires and power to the circuits through best possible ways. The design tool does the routing automatically. After the automatic routing EDA tool shows a net list to be routed manually.

Cost Optimization

After the routing the PCB is defined with inputs and outputs. The next thing is to be considered in cost optimization. Number of issues corresponding to cost optimization are considered. For instance reducing the size of PCB, removing unwanted vias, decreasing spaces and above all the speed checking. The speed analysis defines the performance. Design can decrease speed or power if increased from specification requirements.
After the software simulation and testing the physical PCB is designed as obtained in EDA software.

PCB Physical Design Technology

Designing a PCB is quite a skillful work based on standards and design techniques or technologies. There are basically three design techniques associated with PCB designing.

• PCB Milling
• SILK SCREEN Printing
• Photoengraving