Printed circuit board (PCB), also known as printed circuit board or printed circuit board board

Printed circuit board (PCB), also known as printed circuit board or printed circuit board board, 1oz vs 2oz is the support body of electronic components and the carrier of electrical connection of electronic components. In the electronics industry, almost every type of electronic device, from electronic watches and calculators to computers, communications electronics, and military weapons systems, as long as there are integrated electronic components, in order to make the electrical interconnection between the individual components, printed circuit boards are used.

Next, let's take a look at the five important common sense that the PCB industry needs to know.

PCB industry chain:

The industrial chain of PCB from top to bottom is: raw materials for upstream enterprises - midstream production and manufacturing - downstream PCB applications, as shown in the figure below.

PCB board industry chain

A notable feature of PCB is its wide range of downstream applications, how to test a circuit board with a multimeter including computers, communications, consumer electronics, industrial control and medical, military, semiconductor and automotive industries, almost all electronic information products. Among them, computers, communications and consumer electronics are the three major application areas, accounting for about 70% of the output value of the printed circuit board industry.

Classification of copper-clad plates

Copper clad plate is the upstream core material of PCB manufacturing. It is a plate-like material made of resin impregnated electronic glass fiber cloth or other reinforcing materials and covered with copper foil on one or two sides by hot pressing. It accounts for about 20% to 40% of PCB production costs, and has a strong interdependence with PCB.

1) According to the mechanical stiffness, the copper clad plate is divided into rigid copper clad plate and flexible copper clad plate.

2) According to the different insulation materials and structures, it can be divided into organic resin based copper clad plate, metal based copper clad plate and ceramic based copper clad plate.

3) According to the thickness of copper clad plate, we can be divided into design thick plate (plate thickness range is 0.8 ~ 3.2mm (including Cu)), thin plate (plate thickness range is generally less than 0.78mm (excluding Cu)).

4) According to the reinforcement material of the copper clad plate, it is divided into glass cloth copper clad plate, paper copper clad plate and composite material copper clad plate (CME-1, CME-2).

5) According to the flame retardant grade is divided into flame retardant plate and non-flame retardant plate: according to the UL standard (UL94, UL746E, etc.). Rigid copper clad plates can be divided into four different flame retardant grades :UL-94v 0; UL-94 v1; UL-94V2 and UL-94HB.

PCB design

PCB design is an important research and development work that connects hardware circuit board schematic design and circuit board manufacturing:

1) At the beginning of the project, it is necessary to check whether all the information required by the project is complete, including schematic diagram, structural diagram, package library, signal flow diagram of complex products, power tree diagram, key signal description, power current, design requirements, etc.

2) Design information system input: including the import of netlists and structure diagrams. After the structure diagram can be imported, the size of the screw hole and some enterprise positioning holes, the forbidden area of the device and the cable, the height limit processing area, and the connection position of the connector should be paid special attention to.

3) Layout: Reasonable arrangement of equipment based on full consideration of signal quality, electromagnetic compatibility, thermal design, DFM, DFT, structure, safety and other requirements. The basic idea of layout is generally to combine signal flow and power flow in addition to the limitations of the structure.

4) Wiring constraints: wiring constraints are mainly divided into line width, pitch size and equal length. Some rules need to be guided by pre-simulation, such as line length, impedance, topology, laminated structure, and so on.

5) Wiring: Wiring is the most heavy work in PCB design, and there are many areas that need attention, such as impedance, reference surface continuity, EMC, Si/Pi, DFM, etc.

6) Audit + verification after simulation: After the wiring is completed, it needs the review and inspection of senior personnel of the department, as well as the simulation of key signals and power supplies.

7) Processing: After the PCB design is no problem, it can be produced by the output light drawing file system.