Patent ID: 7569935

Claim:
A pillar-to-pillar flip-chip assembly primarily comprising: a substrate having a top surface, a corresponding bottom surface, a solder mask on the top surface and a plurality of bump pads on the top surface exposed from the solder mask; a chip disposed on the top surface of the substrate, the chip having a plurality of bonding pads disposed on an active surface; a plurality of first copper pillars disposed on the bonding pads; a plurality of second copper pillars disposed on the bump pads; and a soldering material electrically and mechanically connecting the first copper pillars and the second copper pillars, wherein a first height of the first copper pillars protruding from the active surface is the same as a second height of the second copper pillars from the solder mask so that the soldering material has a plurality of central points formed on an equal-dividing plane between the chip and the substrate.