US Patent 7786568 Window BGA semiconductor package

A WBGA semiconductor package primarily comprises a substrate, a chip, a chip-bonding adhesive, a plurality of bonding wires electrically connecting the chip and the substrate, an encapsulant to encapsulate the chip and the bonding wires, and a plurality of external terminals disposed under the substrate. The substrate has a depression for accommodating the chip-bonding adhesive and a slot for passing through bonding wires. The chip is partially embedded in the depression to dispose on the substrate. During the chip bonding step, the chip-bonding adhesive is confined in the depression in a manner to fill the gaps between the sides of the first chip and the inwalls around the depression to generate a non-planar adhering interface by partially covering the sides of the first chip. Therefore, the total package thickness is reduced, the delamination of the passivation layer and the fractures at the sides of the chip are avoided.