Different Types of QFNs
Two types of QFN packages are common: air-cavity QFNs, with an air cavity designed into the package, and plastic-moulded QFNs with air in the package minimized.
Less-expensive plastic-moulded QFNs usually limited to applications up to ~2–3 GHz. It is usually composed of just 2 parts, a plastic compound and copper lead frame, and does not come with a lid.
In contrast, the air-cavity QFN is usually made up of three parts; a copper leadframe, plastic-moulded body (open, and not sealed), and either a ceramic or plastic lid. It is usually more expensive due to its construction, and can be used for microwave applications up to 20–25 GHz.
QFN packages can have a single row of contacts or a double row of contacts.
Read more about this topic: Quad-flat No-leads Package
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