How to Design a PCB Board?

How to Design a PCB Board?

PCB was born in 1936, and the United States widely used this technology in military radios in 1943. Since the mid-1950s, PCB technology has been widely adopted. At present, PCB has become the “mother of electronic products”, and its applications have almost penetrated into various terminal fields of the electronics industry, including computers, communication, consumer electronics, industrial control, medical instruments, national defense and military, aerospace and other fields.

Thanks to the continuous advancement of technology, the volume of PCB boards continues to decrease, costs decrease, and performance continues to improve. These advancements still maintain strong vitality in the application of electronic devices. So how is PCB designed? After reading the following seven steps, you will understand:

1. Prepare in Advance

Including the preparation of component libraries and schematics. Before continuing with PCB design, first prepare the SCH schematic component library and PCB component packaging library.

It is best for the PCB component packaging library to be constructed by engineers based on the standard dimensions of the selected components. In principle, first establish the component package library for PC, and then establish the schematic SCH component library.

PCB component packaging libraries have higher requirements, which directly affect PCB installation; The requirements for the SCH component library in the schematic diagram are relatively relaxed, but we need to pay attention to defining pin attributes and their corresponding relationship with the PCB component package library.

How to Design a PCB Board?

2. PCB Structure Design

Draw the PCB frame in the PCB design environment based on the determined circuit board size and various mechanical positioning, and place the required connectors, buttons/switches, screws, holes, assembly holes, etc. according to positioning requirements.

Fully consider and determine the layout area and non layout area (such as the range of screw holes being non layout areas).

3. PCB Layout Design

Layout design is the process of placing parts in a PCB frame according to design requirements. Generate a netlist in the schematic tool (Design → Create Netlist), and then import the netlist in the PCB software (Design → Import Netlist). After successfully importing the network table, it will exist in the software backend. Through the Placement operation, all components can be retrieved, with a flying wire indicating connection between each pin. At this point, the devices can be laid out.

PCB layout design is the first important process in the entire PCB design process. The more complex the PCB board, the more it can affect the implementation of the entire layout.

Layout design relies on the circuit foundation and design experience of circuit board designers, which is a high-level requirement for circuit board designers. The main circuit board designers lack experience and are suitable for small module layout design or low difficulty PCB layout design tasks.

4. Design of PCB Layout Rows

PCB layout line design is the most labor-intensive process in the entire PCB design, which directly affects the PCB. In the process of PCB design, there are usually three areas for layout lines: the first is layout work, which is the most basic entry-level requirement for PCB design. Secondly, the electrical performance is met. This is the standard for measuring whether a PCB board is qualified. Finally, after the layout is completed, it is carefully adjusted to achieve optimal electrical performance. The layout requirements are neat and uniform, with no rules for vertical and horizontal.

5. Layout Optimization and Screen Layout

PCB design is not the best, only the better. PCB design is a flawed art, mainly because PCB design needs to meet various aspects of hardware design requirements, and personal needs may conflict. For example, after evaluation, the PCB design project needs to be designed as a 6-layer board by the circuit board designer. However, due to cost considerations, the product hardware must be designed as a 4-layer circuit board, so the signal shielding ground plane can only be sacrificed, resulting in adjacent layouts. Interlayer signal crosstalk increases and signal quality decreases.

The general design experience is that optimizing the layout takes twice the initial layout time. After completing the PCB layout optimization, post-processing is required. The first thing to deal with is the screen imprint on the surface of the PCB board. The bottom screen printed characters need to be mirrored during design to avoid confusion with the top screen printing.

6. NetworkDRC Inspection and Structural Inspection

Quality control is an important component of the PCB design process. The general quality control methods include: design self inspection, design mutual inspection, expert review meetings, special inspections, etc.

The schematic and structural element diagrams are the most basic design requirements. The network DRC check and structural check are to confirm that the PCB design meets the two input conditions of the schematic network table and the structural component diagram.

Universal circuit board designers will have their own accumulated design quality checklists, some based on company or departmental standards, and others summarized based on their own experience. Special inspections include Valor inspections and DFM design inspections. These two parts mainly focus on PCB design output and backend processing of lithography files.

7. PCB Manufacturing Board

Before the PCB is officially processed, circuit board designers need to communicate with the PE of the PCB supplier board to answer the manufacturer’s confirmation on the PCB processing. These include but are not limited to PCB board model selection, line width adjustment, impedance control adjustment, PCB stack thickness adjustment, surface treatment process, aperture tolerance control, and delivery standards.
The above is the entire process of PCB design.

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