Ultra-Thin Power Transistor and Synchronous Buck Converter Having Customized Footprint

A power transistor package comprising:

• a leadframe including a flat plate and a coplanar flat strip spaced from the plate, the plate having a first thickness and the strip having a second thickness smaller than the first thickness, the plate and the strip having terminals;
• a field-effect power transistor chip having a third thickness, a first and a second contact pad on one chip side, and a third contact pad on the opposite chip side, the first pad being attached to the plate, the second pad being attached to the strip, and the third pad being coplanar with the terminals;
• and
• encapsulation compound filling the thickness difference between plate and strip, and spaces between chip and terminals, wherein the compound has a surface coplanar with the plate and the opposite surface coplanar with the third pad and the terminals, the distance between the surfaces being equal to the sum of the first and third thicknesses.

A method for fabricating a power field-effect transistor package, comprising the steps of:

• providing a leadframe including a flat plate and a coplanar flat strip spaced from the plate, the plate having a first thickness and the strip having a second thickness smaller than the first thickness;
• providing a field-effect power transistor chip having a third thickness, a first and a second contact pad on one chip side and a third contact pad on the opposite chip side;
• attaching the first pad to the plate and the second pad to the strip;
• concurrently attaching terminals to the plate and the strip so that the terminals are coplanar with the third contact pad;
• and
• filling the thickness difference between plate and strip and spaces between chip and terminals with an encapsulation compound having a surface coplanar with the plate and the opposite surface coplanar with the third pad and terminals, whereby chip, leadframe and terminals are integrated into a package having a thickness equal to the sum of the first and third thicknesses.