The importance of taking care of EMC from the beginning

It is not infrequent that EMC (Electromagnetic Compatibility) people as those that take in charge of a product when it is already finished. This usually happens because all the EMC tests are performed at the end of the life cycle. Furthermore, it happens because before starting the EMC tests, the product should be completely functional, which means that it can be already shown to the customer or potential clients and tell them Look what a nice project we have created, do you want to buy it? It is very easy to convince them and ourselves that it is matter of few weeks or days between starting the tests and the moment that the first prototype can be sent to the customer. This is normally a painful and expensive mistake.

EMC tests are expensive and time limited because of the cost of the equipments and the lack of laboratories. In addition, there are not many people willing to work on it because of the inherent abstraction of electric and magnetic fields, so you will not find too many specialists ready to solve your problems. Due to all this, it is really important that the EMC is integrated in the first stage of the project and not in the last moment. It can be achieved in different ways:

·   At schematic design: component selection is critical to achieve a good electromagnetic compatibility compliance. Components such as decoupling capacitors, ferrite beads or chokes must be part your component libraries. Furthermore, establish a fluent relationship with a supplier of EMC components so you can test different solutions before integrating them in your design.

·   At the stackup design: great part of the problems found during EMC tests laboratories is produced due to a bad stackup design. All currents must have a return path, it is important to have ground and power planes. Do you think that adding a pair of layers will make your board expensive? Think about the cost of repeating the radiated emission tests several times.

·   At PCB design: location, location, location! This famous quote is not only valid for real state. The placement of components will condition the later routing and therefore the electromagnetic behaviour of the board.

·   At management: EMC tests and the impact of failing at them are underestimated. EMC tests shall be included in the project plan. Resources such as time and people need to be fully dedicated, as well as material resources. Bear in mind that, to perform the tests, a real system is needed, every time is possible. Otherwise, a simulated system has to be built and it has to be as similar as possible to the real one, which in some cases leads into a system the same complex as the one to be certified.

EMC tests have a big impact in a product life cycle since they are mandatory before getting into the market. They are normally hard to pass, but much more if resources are not well dedicated from the beginning. Never underestimate the impact of EMC in your project!