Common Mistakes in PCB Schematic Design

Avoiding slivers

Slivers are small pieces of copper or solder mask that can be very harmful to the PCB’s functionality. They can lead to short circuits and can even cause corrosion of copper. This reduces the life of the circuit board. Luckily, there are a few ways to avoid them. The first is to design PCBs with minimum section widths. This will ensure that a manufacturer will be able to detect potential slivers with a DFM check.

Another way to avoid slivers is to design the PCB so that it is as deep and narrow as possible. This will reduce the chances of slivers during the fabrication process. If slivers are not detected during DFM, they will cause a failure and require scrap or rework. Designing PCBs with a minimum width will help avoid this problem and ensure the PCB is as accurate as possible.

Avoiding faulty thermals

Using the correct thermals is an important step in the PCB schematic design process. Faulty thermals can damage the PCB and cause excessive heat reflow. This can compromise the overall PCB performance, which is not what you want. Poor thermals also decrease the PCB’s durability.

During the design process, thermals can be easily overlooked. This is especially true for PCBs with ultra-small flip-chip packages. A faulty thermal pad could damage the circuit or compromise the signal integrity. To avoid this problem, the schematic design process should be as straightforward as possible.

Thermals are important to the proper operation of any circuit. Faulty thermals can cause problems during the manufacturing process. It is imperative that the design team have the right tools and personnel to detect and rectify any errors in the design. Electromagnetic interference and compatibility issues are also concerns.

Impedance mismatch

Impedance mismatch is an important factor to consider when designing a PCB. The impedance of a trace is determined by its length, width, and copper thickness. These factors are controlled by the designer, and can lead to significant changes in voltage as the signal propagates along the trace. This, in turn, can affect the integrity of the signal.

A good impedance match is necessary for maximum signal power transfer. When tracing high-frequency signals, the impedance of the trace can vary depending on the geometry of the PCB. This can result in significant signal degradation, especially when the signal is being transferred at high frequencies.

Placement of op amp units

The placement of op amp units on a PCB schematic is often an arbitrary task. For example, one might place unit A on the input, and unit D on the output. However, this is not always the best approach. In some cases, the wrong placement can lead to a circuit board that doesn’t function properly. In such cases, the PCB designer should re-define the functions of op amp chips.

Impedance mismatch between transceiver and antenna

When designing a radio transmitter or receiver, it’s important to match the impedance of the antenna and transceiver to ensure maximum signal power transfer. Failure to do so can cause signal loss along the feedline of the antenna. Impedance is not the same as PCB trace resistance, and a design that doesn’t match will result in low signal quality.

Depending on the frequency of the signal, a board with no impedance matching between the antenna and transceiver will exhibit reflections. This reflection will send some of the energy toward the driver, but the remaining energy will continue on. This is a serious signal integrity problem, especially in high-speed designs. Therefore, designers must pay close attention to impedance mismatches on the PCB schematic. In addition to affecting signal integrity, unmatched impedances can cause electromagnetic interference and localized radiation. These signals can affect sensitive components in the PCB.