The PCB is designed to be smaller, faster and cheaper.As the interconnection point is the weakest link in the circuit chain, the electromagnetic property at the interconnection point is the main problem faced by the engineering design in the RF design. Every interconnection point should be investigated and the existing problems solved.

Interconnection of PCB system includes chip to PCB, interconnection of PCB board and signal input/output between PCB and external device.This paper mainly introduces the practical summary of high frequency PCB design by interconnection in PCB board. It is believed that the understanding of this paper will bring convenience to PCB design in the future.

Interconnection between chip and PCB is important in PCB design. However, the main problem of interconnection between chip and PCB is that too high interconnection density will lead to the basic structure of PCB materials becoming a factor limiting the growth of interconnection density.This article shares the practical techniques of high frequency PCB design.For high frequency applications, the following techniques are used to design high frequency PCB with interconnection in PCB boards:

   1, the transmission line to the corner a 45 ° Angle, in order to reduce return loss;

2. High performance insulation circuit board shall be strictly controlled by insulation constant value according to hierarchy.This method is beneficial to the effective management of the electromagnetic field between the insulating material and the adjacent wiring.

3. Improve the PCB design specifications for high precision etching.Consider setting the total line width error to +/-0.0007 inches, managing undercut and cross sections of the wire shape, and specifying the conditions for side wall plating of the wire.The overall management of the geometry and coating surfaces of wiring (wires) is very important for solving the skin effect related to microwave frequency and realizing these specifications.

4. Highlight the presence of tap inductor in the lead, and avoid the use of components with lead.In high frequency environments, it is best to use surface mounted components.

5. For signal perforation, avoid using PTH process on sensitive plate.Because this process will lead to lead inductance at the hole.For example, when a hole in a 20-layer plate is used to connect 1 to 3 layers, the lead inductor can affect 4 to 19 layers.

6. Provide a rich seam connection.A die hole is used to connect these layers together to prevent the impact of a 3-dimensional electromagnetic field on the circuit board.

7. To choose non-electrolytic nickel plating or dip plating process, do not use HASL method for plating.This electroplating surface can provide a better skin effect for high frequency current.In addition, the high solderable coating requires less lead wire and helps reduce environmental pollution.

8. The welding resistance layer can prevent the soldering paste from flowing.However, due to the uncertainty of thickness and the uncertainty of insulation performance, covering the entire plate surface with welding resistance materials will lead to a large change in electromagnetic energy in microstrip design.Solderdam is commonly used as the resistance layer.

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