A method includes attaching a die to a thermal compression bonding (TCB) head through vacuum suction, wherein the die comprises a plurality of conductive pillars, attaching a first substrate to a chuck through vacuum suction, wherein the first substrate comprises a plurality of solder bumps, contacting a first conductive pillar of the plurality of conductive pillars to a first solder bump of the plurality of solder bumps, wherein contacting the first conductive pillar to the first solder bump results in a first height between a topmost surface of the first conductive pillar and a bottommost surface of the first solder bump, and adhering the first solder bump to the first conductive pillar to form a first joint, wherein adhering the first solder bump to the first conductive pillar comprises heating the TCB head.