PCB News - What are the matters needing attention in PCB circuit board proofing?

What are the matters needing attention in PCB circuit board proofing?

PCB proofing is a complicated process, the same board, the same components, different engineers produce different effects. So, what are the matters needing attention in PCB circuit board proofing?

1. Make clear design goals

Receiving a design task, we must first clarify whether the design target is a common board, a high-frequency board, a small signal processing board, or a board with both high frequency and small signal processing. If it is an ordinary board, as long as the layout and wiring are reasonable and tidy, and the mechanical size is accurate.

Second, understand the requirements of the layout and routing of the functions of the components used

Some special components have special requirements in the layout and wiring. For example, the analog signal amplifier must have a stable power supply and low ripple; the analog small signal part should be as far away from the power device as possible; the components with high power consumption and high heat generation must have heat dissipation problems. Special considerations must be taken in the layout.

Three, the consideration of component layout

The first factor to consider is electrical performance. Put components with close connections together as much as possible, especially for some high-speed lines, make them as short as possible during layout, and separate power signals and small signal devices.

Secondly, we must consider the transmission delay time on the ground and interconnection lines in the high-speed system.

Fourth, the consideration of wiring

1. Transmission line

Any "long" signal path on the printed circuit board can be regarded as a kind of transmission line. If the transmission delay time of the line is much shorter than the signal rise time, the main reflections produced during the signal rise period will be submerged, and there will be no more overshoot, recoil, and ringing.

2. Several types of transmission lines

(1) Coaxial cable and twisted pair: They are often used in the connection between systems.

(2) Microstrip line on the printed board: The microstrip line is a strip conductor (signal line), which is separated from the ground plane by a dielectric.

(3) Strip line in the printed board: The strip line is a copper strip line placed in the middle of the dielectric between two conductive planes. 

 
3. Terminate the transmission line

At the receiving end of a line, a resistance equal to the characteristic impedance of the line is used to terminate, then the transmission line is called a parallel terminal connection. It is mainly used to obtain the best electrical performance, including driving distributed loads.

The above are the matters needing attention in PCB circuit board proofing, I hope it will be helpful to you.