PCB Technical - pcb design process

Knowing how to design a printed circuit board, PCB is a key element of any electronic circuit design process. The layout and design of the PCB have a great influence on how the circuit works, so if the PCB design is effective, the circuit will perform more reliably within its specifications.

PCB design results

One, PCB design environment

For commercial development programs, there may be CAD, computer-aided design software packages, which are required due to complexity. Even for students and amateurs, there are many very good packages, whether they are free, they can be obtained at a moderate cost. Free software provides basic functions, while high-end software packages enable more facilities to be incorporated into the design: analog circuits, complex circuits, multilayer circuits, etc. As the speed of digital boards increases, and RF designs reach higher and higher frequencies, the ability to perform analog is becoming an increasingly higher requirement.

Second, the circuit schematic diagram

The first stage of PCB design and development is the schematic design of the circuit, which can be implemented in various ways. Some PCB design software comes with schematic drawing. We import the schematic file into the PCB design tool to generate a "Netlist". The grid table connects each pin and the connected devices and circuit nodes together.

Three, PCB component initialization

Before proceeding with detailed PCB design and layout, it is necessary to roughly understand where the components will be located and whether there is enough space on the board to contain all the required circuits. This will enable people to determine the number of layers required for the circuit board and whether there is enough space to contain all the circuits that may need to be made. Once a rough estimate of the space and approximate location of the components is made, a more detailed component layout can be provided for PCB design. This can take into account aspects such as the proximity of devices that may need to communicate with each other, and other information related to any radio frequency considerations. In order for the component to be incorporated into the PCB design, they must understand all relevant information about the component: including the shape of the circuit board, aperture information, distance from the area, and so on. Usually, several devices may share the same pins, so there is no need to enter this information for each component part number. Establish a package library for all devices in the PCB design. In this way, previously used components can be easily called.

Four, wiring

Once the basic components are placed, the next stage of PCB design is to route the connections between all components. Then, the PCB software performs wiring based on the information in the Netlist table in the schematic. To achieve this, it will use the number of layers available for connection, created through holes as needed. Generally, one layer will be allocated as a GND layer, and the other layer will be allocated as a power supply plane. This not only reduces the noise level, but also enables low source resistance to connect the power. Wiring is time consuming, and the situation is more serious for large designs that may have more than three or four thousand components. When wiring becomes difficult due to multi-component density, this may cause wiring to take a lot of time.

Five, PCB file (gerber)

The information of the photo map of the PCB layout is output in the form of a Gerber file. This format is the standard for PCB files, and they are the form of CNC files used by photo plotters. In addition to Gerber files, drilling information, screen printing and photo saving information are also generated. A major factor in the cost of printed circuit boards is drilling. In any design, some holes are needed for fixing, as well as the holes required for conventional parts. However, in order to reduce costs, it is wise to use as few hole sizes as possible. In this way, the drill bit will require less changes and time can be reduced.

PCB files are used in many areas of the manufacturing process. It is not only used in the manufacture of the PCB itself, but these files will also be used in other areas of the manufacturing process. Such as the production of steel mesh, SMT patch, ICT testing, needle-type testing home and so on. The above is the whole process of PCB design product, PCB design is not only drawing design.