Electronic products must conform to industry and federal standards that ensure trouble-free operation in the presence of electromagnetic interference as well as limiting the amount of interference they generate. Understanding the physics that govern these effects means we design for compliance from the start. It also means we can spot trouble in existing designs. There are two aspects to EMC - emissions from the product and susceptibility to interference.
Design for EMC starts with understanding the electromagnetic environment in which electronic devices must operate and peacefully coexist. If the product does not contain a radio (Bluetooth, wifi, cellular) it is considered an "unintentional radiator." The emissions from the product are not supporting its function, but are rather (unintended) byproducts of its function. Regulatory compliance insures that products don't produce so much interference that they impair the operation of other devices. There are limits for both conducted and radiated emissions. Limiting conducted emissions involves power supply design, I/O and power filtering, proper PCB floor planning, and many other techniques. Limiting radiated emissions involves understanding the sources and paths that allow RF interference to be broadcast through the air. Two designs made from the same schematic can have very different emission and susceptibility profiles, just by how the components are arranged and connected. Protection and filtering components can also be rendered ineffective due to poor layout practice.
There can be many sources of disturbance that affect the operation (and survival) of electronics. Any wire connected to the printed circuit board is a potential carrier of electrical spikes, RF interference, and electrostatic discharge. Any of these can disturb or damage the unprotected product. Each of these potential threats must be considered in the design to ensure smooth progression through qualification testing as well as field reliability.
Design for EMC
In the early design phase of the product, there are countermeasures for all of these threats that are usually inexpensive to include. The cost to remediate EMC issues tends to rise exponentially as product launch time is approached. Why? Because the opportunity to do the inexpensive approaches happens at the schematic and PCB design stage. If the design is done and a problem is found at the end of a $20k qualification test, the options are to add "bandaid" external fixes or respin the design. When you engage us in your product development, EMC is considered at every step from the beginning, never an afterthought.