What Are The Skills Of PCB Design

The goal of PCB design is smaller, faster PCB and lower cost.

And because the interconnection point is the weakest link in the circuit chain, in RF design, the electromagnetic property at the interconnection point is the main problem facing engineering design. It is necessary to examine each interconnection point and solve the existing problems.

The interconnection of the circuit board system includes chip-to-circuit board, interconnection within the PCB board, and signal input / output between the PCB and external devices. This article mainly introduces the practical skills of high-frequency PCB design interconnected in the PCB board. I believe that by understanding this article, it will bring convenience to future PCB design.

In the PCB design, the interconnection between the chip and the PCB is important to the design. However, the main problem of the interconnection between the chip and the PCB is that the interconnection density is too high, which will cause the basic structure of the PCB material to become a factor limiting the growth of the interconnection density. This article shares practical tips for high-frequency PCB design.

For high-frequency applications, the techniques for high-frequency PCB design by interconnecting PCB boards include:

1. The corner of the transmission line should adopt a 45 ° angle to reduce the return loss;

2. A high-performance insulated circuit board with strictly controlled insulation constants at different levels shall be used. This method is conducive to the effective management of the electromagnetic field between the insulating material and the adjacent wiring.

3. It is necessary to improve the PCB design specifications related to high-precision etching. Consideration should be given to specifying a total line width error of +/- 0.0007 inches, managing the undercut and cross section of the wiring shape, and specifying the plating sidewall wiring conditions. The overall management of the wiring (wire) geometry and coating surface is very important to solve the skin effect problems related to microwave frequencies and to achieve these specifications.

4. Protruding leads have tapped inductance. Avoid using leaded components. In high-frequency environments, it is best to use surface mount components.

5. For signal vias, avoid using via processing (pth) on sensitive boards. Because this process will cause lead inductance at the via. If a via on a 20-layer board is used to connect layers 1 to 3, the lead inductance can affect layers 4 to 19.

6. Provide a rich ground plane. Use molded holes to connect these ground planes to prevent the influence of 3D electromagnetic fields on the circuit board.

7. To choose non-electrolytic nickel plating or immersion gold plating process, do not use HASL method for electroplating. This plating surface can provide better skin effect for high-frequency current. In addition, this highly solderable coating requires fewer leads, which helps reduce environmental pollution.

8. The solder mask prevents the solder paste from flowing. However, due to the uncertainty of the thickness and the unknown of the insulation performance, the entire surface of the board is covered with solder resist material, which will cause a large change in the electromagnetic energy in the microstrip design. Solder dams are generally used as solder masks.