Electromagnetic interference is a concern for many electrical component manufacturers and engineers that must adhere to national and international EMC (electromagnetic compatibility) standards. However, there are various methods that can be used to lower emissions and improve immunity to EMI in order to attain EMC certification and compliance.
Designers have to take many engineering options into consideration when building their gadgets. From casing decisions to component choices, the construction and design of a product require considerable effort and time. One of the major concerns to the designer is how well their product will fare when subjected to EMI tests.
Why Designs May Fail EMC Testing
Avoiding a failed EMC compliance test involves using basic design rules during the design and manufacturing stages. To avert costly EMC compliance failures, we will discuss below some basics of designing for EMC compliance.
Avoid Interrupting the Signal Return Plane
Inserting a cut, gap or split in the ground or signal return plane is rarely necessary for most boards. Adding these interruptions can lead to more problems that could have been easily averted. The main problem you will have to deal with is the increased effort and time required to come up with ways to manage the flow of low-frequency currents.
If you are convinced that your printed circuit board requires a cut, gap or slip in the ground return plane to prevent low-frequency coupling issues, it’s highly advisable to seek professional assistance or advice before inserting these additions. A professional can evaluate your design, offer suggestions and help you find a solution that will help you implement the cut, gap or split effectively.
It’s important to note that something that worked on a similar board or design may not work the same in yours.
Avoiding Placing High-Speed Circuitry Between Connectors
This is a very simple rule that many designers tend to forget. Overlooking this crucial detail can lead to a bloated design that needs more additional filtering and shielding than necessary.
The placement of connectors on a board is important because the cabling linked to these connectors act as good antennas. While printed circuit board traces can also behave as antennas, their effect is usually negligible when compared to the wavelength at these frequencies. This makes printed circuit board traces poor radiators.
This is typically not an issue when the connectors are placed along a single edge on a PCB because the voltage between them is tiny. However, when high circuitry is placed between the connectors, greater potential differences can occur, causing radio frequency currents on the cables’ conductors and/or shield. This can result in the cables emitting radiation, potentially interfering with the product EMC compliance requirements.
Ensure Auxiliary Equipment Is Compliant
During EMI testing, manufacturers are required to connect auxiliary equipment to all input and output ports using cables available in the market. This test is done to ensure that all ports within the gadget are working as required. This test is crucial in EMC compliance because the use of any incompatible auxiliary equipment can cause problems. For instance, using a non-compliant gadget, like a low-quality USB drive, the EMI tests can produce poor results.
This is not a result of poor PCB design; it is due to non-compliant auxiliary equipment. The poor results caused by this non-compliant auxiliary equipment can take you and your team back to the drawing as you try to figure out the source of these emissions problems. This unnecessary investigation can delay your product release and cost your company a lot of money and man-hours.
Find a Trusted Expert In EMC
One of the best ways to design your product for EMC compliance is to work with a trusted expert in EMC who will guide you on all the intricate details regarding EMI tests and design principles.
Compliance Engineering offers accredited testing services for a broad range of products in particular compliance with EMC regulations in Australia. We provide the highest standard of environmental testing that measures the performance of specific products under particular environmental conditions.
Please call us today at Compliance Engineering on + 61 3 9763 3079 or leave an enquiry.