Evaluating Class Two Permissive Change Triggers for Encapsulated Modules
Class Two Permissive Changes are triggered when physical, antenna, or firmware modifications alter RF emissions or RF exposure without exceeding original grant limits.
Shield Encapsulation
Meaning
Mechanical overmolding processes apply conductive shielding materials directly over surface-mounted components on circuit boards. Utilizing shield encapsulation eliminates the need for soldered metal cans, reducing overall wireless module height and board footprint. Microscopic metal particles dispersed inside epoxy resins create an electrically continuous ground plane over sensitive radio frequency circuitry.
The physical boundary extends from the substrate ground pad to the outer surface of the molded compound.
Material Deposition
Automated dispensing equipment coats target component regions with conductive epoxy or sprayed metallic slurry. Curing ovens harden the resin matrix to form a durable protective shell over sensitive components. Precision cutting tools expose ground contact pads along substrate edges.
Ground connections route interference currents.
Electromagnetic Isolation
Conductive particle networks absorb and reflect radiated electromagnetic interference across target frequency bands. Attenuation levels above thirty decibels prevent cross-talk between high-power transmit power amplifiers and sensitive receiver low-noise amplifiers on the same board. Compact physical geometry reduces stray capacitance between components and shielding walls.
Thermal dissipation improves through direct resin contact.
Qualification Testing
Reliability assessment subjects encapsulated modules to thermal shock and high humidity. Laboratory equipment measures attenuation performance across radio frequency spectrum bands before and after environmental stress cycles. Inspection reports confirm that shield encapsulation maintains physical adhesion without micro-cracking across operational temperature ranges.