Power device with bottom source electrode and preparation method
AssigneeAlpha and Omega Semiconductor Incorporated
InventorsYan Xun Xue, Yueh-Se Ho, Hamza Yilmaz, Jun Lu, Lei Shi, Liang Zhao, Ping Huang
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Abstract
A power semiconductor package has an ultra thin chip with front side molding to reduce substrate resistance; a lead frame unit with grooves located on both side leads provides precise positioning for connecting numerous bridge-shaped metal clips to the front side of the side leads. The bridge-shaped metal clips are provided with bridge structure and half or fully etched through holes for relieving superfluous solder during manufacturing process.
Claims19
A power device with bottom source electrode comprising:
- a lead frame unit comprising a first base and a second base separated from each other, a third base and a fourth base located at two opposite sides of the first base;
- a primary packaging structure attached to the first base and the second base, the primary packaging structure comprising a front surface and a plurality of solder bumps formed thereon, said solder bumps being further attached respectively to the first base and the second base;
- a bridge-shaped metal clip attached atop the primary packaging structure, the bridge-shaped metal clip comprises a top metal portion and side metal portions that are:
- connected to two opposite sides of the top metal portion;
- and
- are bent downwards
- such that a first predetermined members of the side metal portions are positioned and trapped into a groove formed on the top surface of the third base and a second predetermined members of the side metal portions are aligned and positioned and trapped into a groove formed on the top surface of the fourth base;
- a bottom metal layer formed at a back surface of the primary packaging structure and connected to a bottom surface of the top metal portion through a conductive material;
- and
- a plastic packaging body encapsulating the lead frame unit, the primary packaging structure and the bridge-shaped metal clip, wherein the bottom surfaces of the first base, the third base and the fourth base are all exposed through the bottom surface of the plastic packaging body.
A method for packaging a power device with bottom source electrode comprising:
- providing a lead frame unit comprising a first base and a second base separated from each other, a third base and a fourth base respectively located at two opposite sides of the first base;
- forming, flipping and attaching a primary packaging structure onto the first base and the second base, wherein a plurality of solder bumps are pre-formed on a front surface of the primary packaging structure and are respectively pre-attached to the first base and the second base;
- attaching a bridge-shaped metal clip atop the primary packaging structure, wherein the bridge-shaped metal clip comprises a top metal portion and side metal portions connected to two opposite sides of the top metal portion and bent downwards, wherein the side metal portions are positioned and trapped into a groove formed on the top surface of the third base and a groove formed on the top surface of the fourth base, and a bottom metal layer formed on the back surface of the primary packaging structure is attached to the bottom surface of the top metal portion through a conductive material;
- and
- forming a plastic packaging body encapsulating the lead frame unit, the primary packaging structure and the bridge-shaped metal clip, wherein the bottom surfaces of the first base, the third base and the fourth base are exposed through the plastic packaging body.
Dependencies are inferred from the claim text.