Electrical devices operated in close proximity may sometimes interfere with one another. This interference may hamper the signals and create disturbances in their function. For instance, this type of interference may be observed when you keep your mobile phones or GSM sets near the television or a land phone. How to mitigate this type of interference? Well, this can be easily managed through electromagnetic compatibility or EMC. What does this term indicate? Are there any solutions assuring EMC? If yes, what are they? Read this post to know the answers to all these questions and more.
An Overview of Electromagnetic Compatibility
Any modern environment may be comprised of many electronic devices and systems. Electromagnetic compatibility is the capability of these systems and devices to work amicably in the electromagnetic spectrum without interfering with each other's or their own performance. Electronics manufacturers take extreme care to design devices to minimize the effect of electromagnetic interference. Likewise, they implement several EMC measures so the devices they create will not adversely affect other devices.
Factors Addressed by Electromagnetic Compatibility
The following are the two factors that electronics OEMs need to address to ensure the electromagnetic compatibility of their devices.
- Immunity and Susceptibility: The device must be susceptible and immune to electromagnetic interference. Here, susceptibility is the virtue of the device to withstand electromagnetic energy. Immunity allows these devices to withstand interference and work normally.
- EMI Emissions: Every electronic device emits electromagnetic energy. This energy must be reduced to certain limits to avoid interference with other devices. Most governments have agencies which define allowable EMI emissions.
A Brief Introduction to EMC Regulations
Every country in the world has regulated EMC of electronic products sold there. The following are two important regulations enacted by the US and the EU.
- The FCC Rules and Regulations, Title 47, Part 15: All commercial electronic systems and equipment manufactured and operated within the US are regulated by the Federal Communications Commission (FCC). The regulation limits on the radiation from both unintentional and intentional radiation sources. As per this standard, the electronic products are marked in two classes – Class A and Class B. Class A devices are marked for commercial and industrial use and Class B are marked for residential uses. Some electronic devices are exempted from meeting Part 15 requirements, and they are automobiles, scientific, and medical equipment. Part 15 regulates EMI emissions, but not electromagnetic fields. The EMI limit results for class A and B devices are as given below.
FCC Class
Frequency of Emission (MHz)
Quasi-peak Limit (dBμV)
Average Limit (dBμV)
A
0.15 - 0.50
79
66
0.50 - 30.0
73
60
B
0.15 - 0.50
66 to 56*
56 to 46*
0.50 - 5.00
56
46
5.00 - 30.0
60
50
EMC requirements for military electronics is documented in MIL-STD-461. This standard covers everything from various electronic hand tools used in military environments to equipment. This MIL-STD has set limits for conducted and radiated immunity and emissions.
- European Union: The Electromagnetic Compatibility Directive (EMC Directive, 2004/108/EC) regulates the immunity and electromagnetic emissions of electronic devices. This directive states that the electronic devices designed for use in the EU must be labeled and tested according to the harmonized EC standards. There are two standards – CISPR 32 and IEC 6000. The former standard places limits on radiated and conducted emissions and the latter on immunity requirements of the wide range of products.
Note: Many countries specify compliance with EU or FCC requirements. However, several countries like Canada, Australia, Finland, Japan, and Germany have developed their own requirements.
Consequences of Not Meeting Electromagnetic Compatibility
Non-compliance with established EMC standards may lead to:
- Product recalls or withdrawals from the market
- Damage to brand reputation
- Heavy fines and a total ban on the use of the product in commercial and industrial environments
- Inability to launch a market a product
What Are Some Popular EMC Measures Taken by Electronic OEMs to Ensure Compatibility with EMC Standards
Nowadays, most electronics OEMs address EMC on a broad level by taking factors such as coupling mechanisms, circuit components and parasitics, signal routing and termination, etc, into consideration. They design components to minimize the effects of electromagnetic interference. Various electromagnetic shielding solutions have been developed over the years to ensure the electromagnetic compatibility of devices. The following are some popular ones among them.
- EMI Shielding Gaskets
- Conductive Silicones
- EMI Materials
- EMI Shielding Metal Cans
- Microwave Absorbers
- Board Level Shields
Among these, EMI shielding metal cans and board-level shields have gained immense popularity due to their application effectiveness. However, they have their own limitations imposed by rigidity and lack of flexibility. This is where flexible board-level shields make a difference. There are one and multi-cavity shields available in the market. However, SnapShot® EMI shields stand tall among them.
How SnapShot® EMI Shields Assure Better Electromagnetic Compatibility Than Other Similar Products
SnapShot EMI shields are single or multi-cavity shields that are designed to overcome the challenges of traditional PCB shielding technologies. The following pointers will help you understand it better.
- The shields are made from lightweight metalized plastic with the “snap-in-place” technology. This snapping mechanism allows for easy removal and reapplication of shields with no soldering necessary.
- The metallized plastic features conductive outer surface made of tin and non-conductive inner surface made of polyetherimide (PEI).
- This non-conductive interior surface eliminates shorting threats.
- PEI is a sturdy yet lightweight material, which further helps reduce the size and weight of the shield. These shields weigh only 10-20% of metal shields reducing the shield weight by 80-90%.
- They are attached to the PCB by snapping over solder spheres, which
create strong electromechanical connection. - PCB shields are thermoformed to virtually any shape. Each shield is custom designed to meet the shape and size requirements of the layout.
- There are multiple height profiles in a single shield.
- These PCB shields can be easily installed after the reflow process for unobstructed rework and inspection. This is in addition to more even heating for the entire board during reflow. These EMI shields are proven to withstand shock, moisture, vibrations, and aging. They are extensively tested against the following:
- Bump (IEC 60668-2-29)
- Vibration (IEC 60068-2-64)
- Mechanical Shock (OEDEC JESD 22-B104-B)
- Thermal Shock (MIL-STD-883CA)
- Dry Heat Aging
- Moist Heat Aging
- SnapShot® assures better shielding effectiveness from below 500 MHz up to 12 GHz.
- They assure extremely consistent isolation across a wide range of frequencies.
- Excellent electromagnetic compatibility assured by these shields has contributed to their increasing use in many critical electronic devices such as medical electronics, GPS based devices, handheld devices, drones and avionics, and network computers.
Do you have specific electromagnetic compatibility needs? Do you wish to know more about the EMC capabilities of these shields? Feel free to get in touch with the team at XGR Technologies. The experts at the company will help you find the right SnapShot solution for all your requirements.
