Historically, power die like MOSFETs have been packaged on lead frames using wire bonds asinterconnects. To facilitate current carrying requirements, thick wires and sometimes also clips were used, to handlethe total electrical and thermal conductivity requirements. As die are being thinned, it has become possible to takeadvantage of new electrical designs and locate source and drain on opposite sides of the die. Such die can now beeasily packaged by embedding the power die in organic substrates. The die is bonded on a Cu pad and covered byprepreg and copper foil during lamination. Source, drain and gate pads are accessed from the top side with laser viasand filled with plated copper. Finally, the top side is patterned and protected with solder mask. Electrical andthermal modeling data can demonstrate the performance efficiency while reducing the form factor in accordancewith the miniaturization requirements of mobile applications. Aside from single die packages, more advancedpackages can be built containing multiple power die and controller die. The basic process flow remains the samebut does require some adaptation. If so desired, additional components may be assembled on top of the embeddeddie package leading to further integration and miniaturization.
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