High speed PCBs are used in critical applications. They need to be deigned to ensure maximum reliability. Any factors that act as deterrents to this final goal should be looked into and rectified or eliminated. Noise in PCBs is one of the major deterrents of performance. Several design changes can be implemented to ensure low levels of on-board noise in PCBs.
Design Guidelines for High Speed PCBs: Avoiding On-board Noise
The following are some of the reasons for noise to be prevalent in a high speed PCB. They should be avoided to ensure proper functioning of the PCB.
Crosstalk is the unwanted capacitive and inductive coupling between parallel traces. The method of routing traces plays an important role in occurrence of crosstalk. Traces routed side-by-side are less likely to cause crosstalk than those routed parallel to one another. The trace segments that do run in parallel to one another should be kept as short as possible. Additionally, the dielectric height can be reduced to decrease crosstalk. Widening the spaces between the traces is also a helpful in reducing crosstalk.
2. Cold Solder Joints
Cold solder joints are caused due to improper welding processes. They can cause static noise, erratic cutouts, and other problems. To avoid this, the soldering iron should be heated to the right temperature. The joint to be soldered should also be heated by placing the tip of the soldering iron on it. The solder should then be applied to the joint. Ensure that the solder melts properly and covers the joint completely. Soldering flux can be used to improve the soldering process as well.
These design guidelines for high speed PCBs will allow you to eliminate noise. Although elimination and control of on-board noise is important in all PCBs, it is especially significant in high speed PCBs that are operating in a low power environment. Strong signal integrity and low noise levels will ensure unfailing functioning of the high speed PCB.