The circuits present in electrical devices are sensitive to electromagnetic interference (EMI) and have to be isolated from their surroundings. Shielding is the practice of protecting the electronic circuits by reducing the electromagnetic field in a space with the help of barriers made of conductive or magnetic materials. RF shielding is a similar concept where the radio frequency electromagnetic radiations are blocked. All this is done by simple metal enclosures called shield cans.
What exactly are shield cans?
Often termed as cans, cages, covers, lids or metal shields, these are metal boxes mounted directly to the PCB (printed circuit board) to enclose it completely. The cans play the key role in keeping the harmful interference out and the unwanted emissions in.
These cans are attached to the PCB using through-hole solder tails and contribute to keeping the component and assembly costs low without compromising the appearance and ease of maintenance of the product at any stage.
They are usually made of metals that can be any of these – steel, aluminum, brass, copper alloys, silver, etc.
What are the benefits of shield cans?
With PCBs shrinking with each passing day, the shield cans are indeed the best invention. They have provided numerous benefits, some of which are listed as below –
- They have provided greater levels of interference suppression without adding mass, weight or cost to the device.
- They have helped with thermal management and successfully kept the EMI from entering or leaving the covered region.
- They are very easy and affordable to install as there is no secondary processing required and the assembly takes just a few seconds.
- They are mechanically robust and are resistant to shock and vibration.
- They save huge cost in comparison to the fence and cover styles.
- They can be easily removed during inspection, repair or rework without any fear of damage to the PCB.
What are the applications of shield cans?
These cans are beneficial for many industries and markets as they aid in the optimization of automated processes and elimination of hand assembling processing. Due to their cost effectiveness, they are extensively used as a shielding material for aerospace and military tools, in wireless equipment and consumer electronics.
As per your specification, you will get anything from enclosure shields to multi-level shields. You can get them custom-built and use it for telecom base stations, radio communications, data processing or in-car information systems.
How to attain the perfect integration?
When you identify the components that require shielding, you should calculate the appropriate shield size – not on the basis of just the external dimensions but the internal ones, especially the height to perfectly fit your components.
Then you have to add solder pads around the components on your PCB so you can attach the cans to the board. You can also use clips or frames to do that. But just make sure it is removable so you are free to rework under the cans anytime.
You can also get them custom-made based on your requirement. It will be a costly affair, but surely worth it.