Meaning
Finished semiconductor devices enclosed in a protective polymeric or ceramic housing to shield them from environmental and mechanical damage. For encapsulated microelectronics, the primary purpose of the housing is to prevent moisture ingress, dust contamination, and physical stress during board-level assembly. The packaging process involves molding compound application and curing around the lead frame or substrate.
It holds the active silicon die in a stable orientation for long-term electrical contact.
Material Selection
Epoxy molding compounds filled with silica particles represent the most common material used for general consumer products. The selection of the silica filler content determines the coefficient of thermal expansion, which must match the silicon die and the printed circuit board to minimize thermal stress. For high-reliability or aerospace applications, ceramic or glass-sealed packages are utilized instead of organic polymers.
These materials offer superior hermeticity and resistance to temperature extremes.
Manufacturing Method
Transfer molding or injection molding techniques deliver the liquefied compound into the mold cavity containing the mounted die and wire bonds. The system operates under high pressure to ensure that the compound fills all voids without damaging the delicate gold or copper wires. After injection, the package undergoes a post-mold cure cycle in an oven for several hours to achieve full cross-linking of the polymer.
This step is followed by trim and form operations to shape the external leads.
Quality Assurance
Production lines in coastal Chinese provinces employ acoustic microscopy to scan the finished packages for internal delamination or voids. When the packaging material detaches from the silicon die or the lead frame, it creates a moisture path that leads to popcorn-like cracking during solder reflow. Quality managers run pressure-cooker and thermal-cycling tests on sample batches to verify the package integrity before shipment to international buyers.
The test logs are maintained to prove compliance with industrial reliability standards.
