Patent ID: 8104666

Claim:
A method comprising: providing a first work piece; attaching a second work piece on the first work piece, with a first solder bump between the first and the second work pieces; heating the second work piece using a heating head of a heating tool to melt the first solder bump; after the step of heating the second work piece, allowing one of the first and the second work pieces to move freely in a horizontal direction to self-align the first and the second work pieces, wherein the step of allowing one of the first and the second work pieces to move comprises: releasing the second work piece from the heating head; and after the step of releasing the second work piece, lifting the second work piece up using the heating head, with the first solder bump being melted during the step of lifting, and wherein the first work piece is fixed in position and does not move along with the second work piece; and after the step of lifting the second work piece, lowering a temperature of the heating head until the first solder bump solidifies to form a second solder bump.