RFI multi cavity enclosures
Multi cavity enclosures are used as an alternative to multiple enclosures fitted to the same side of PCB, usually where access is required within the enclosure, via a removable lid.
levels of shielding
These enclosures are used to reduce cross-talk or inter-channel interference between different portions of the circuitry as well as for EMC with the outside world.
The benefits of multi-cavity enclosures over individual cans include:
- Reduction of board real estate taken up by the individual cans.
- Reduction in PCB assembly time if the individual cans are being hand placed or hand soldered.
The real estate problem is not just one of two separate enclosure walls but if spring finger lids are used then clearance is required to remove and replace these.
labyrinths
The fence portion of these enclosures is usually referred to as a labyrinth.
Labyrinths are produced in an assembly jig to ensure that the walls are parallel and consistent with the PCB footprint and the PCB edge is flat to better than 0.1mm on any one length or junction and 0.2mm overall. (co-planarity). Lids can be tag and slot, spring finger or plain flat with a form-in-place gasket to ensure continuous connection between the labyrinth walls and the lid itself.
The jointing method used will depend on the base material and finish which in turn is dependant on whether the product is RoHS compliant and using non-lead solder for the PCB assembly.
handling
Labyrinths are generally seam-soldered to the PCB and although they need careful handling they have considerable benefits in specific applications. They are usually hand-placed onto the PCB between the electronic component pick-and-place machine and the reflow oven.
why use chemical etching for RFI shields?
Chemical etching from Tecan allows for precise and intricate designs to be achieved with high accuracy. It ensures that shields are consistent in depth and uniformity, which is crucial for their effectiveness in blocking electromagnetic interference. Performance is further enhanced as chemical etching results in burr-free edges – essential to maintaining signal integrity and meeting stringent requirements for electromagnetic compatibility.
Additionally, chemical etching is a cost-effective manufacturing process, especially for producing RFI shields in large quantities. The ability to create complex patterns and shapes with minimal tooling costs makes it a favorable choice for many industries.
- faster production cycles
- minimal tooling costs
- design flexibility
- inclusion of complex patterns and shapes (e.g. features like access holes, ventilation, fold lines, logos, and part numbers) at no additional cost
- short timescales, even at high volume
- cost-effective
