Designers and engineers sometimes take the long route in trying to solve simple problems encountered in their design layouts. Some of the problems present themselves as huge whereas they are minor problems that do not need a lot of time and cost to take care of. PCB noise, caused by undesirable electric signals or electromagnetic interferences, which if left unattended, can lead to failure of the board that would cost the company thousands of shillings.
Preventing the noises requires a lot of knowledge, planning and understanding of all the cables, wires and other component parts that are susceptible to noise. It is only then that an electrical engineer can come up with the right type of shielding method to use to stop the noise. In most cases, all it really takes is very simple shielding instead of highly expensive triple laminate foil and high braided shielding materials.
Data cables and heavy industrial network circuits have very high frequency signals. These cables require aluminum foils around them to protect them against any degradation of the signal. Below are a few ways in which engineers can help prevent electric noise.
EMI (Electromagnetic Interference)
There are two kinds of EMI. These are Conducted EMI and Radiated EMI. In conducted emi, the noise signals travel through the wires, ground planes and others. If left unshielded, they cause a cable cross talk, which leads to system power.
In radiated EMI, magnetic and electric fields travel through the space to the receptor from the source. These fields, radiated by sources like magnetic sources, motors transformers and generators, If left unshielded, they too become catastrophic and may slow down production.
ESD (Electrostatic Discharge)
Electrostatic discharge is another major cause for electric noise. ESD brought about by contact and later separation of two static elements causes a transfer of electrons between them. The buildup of the esd starts slowly before rapidly breaking down. This fast and unexpected breakdown causes EMI problems in electronic systems leading to serious noise problems. In the process, damages to circuits and several electromagnetic coupling problems follow thereafter. Checks and shielding prevents this from getting out of hand. In addition, taking precautionary measures saves the company a lot of money.
Fly back diodes
Sometimes large voltage spikes cause PCB to develop mechanical problems. Using flyback diodes to the circuit controls the voltage spikes thus reducing any electrical noises. The flyback diode is placed in reverse from the power supply but parallel to the inductance coil. When the power is disconnected, the diodes prevent high voltage spikes. When the power is reconnected, the voltage from the inductance coils builds up to match the voltage from the power source. This brings about a constant flow and prevents a voltage buildup called a flyback.
A flyback is capable of damaging all the components controlling the power relay and introduce enormous electric noise to the adjacent 6 signals and connections. This in turn may lead to a crash or reset of the microcontrollers. This is why it is very important to use the flyback diodes to prevent electric noise.
While in some cases the designer may have absolutely no control over the electric noises, there is no reason why they should not carry out regular checks and testing on all the wires, cables, ground planes etc. to ensure of their safety and to ensure that the flow of current is smooth. Use shielding materials and flyback diodes to make sure there are no electric noises that bring about lots of catastrophes.