Package on package structure and method for forming the same

An apparatus, comprising:

• a substrate;
• a package including a first semiconductor die surrounded by a molding compound, wherein the first semiconductor die of the package is bonded to the substrate by a first conductive bonding structure;
• and
• wherein first conductive bonding structure includes a metal ball made of non-solder material, a layer of solder over a surface of the metal ball, and an intermediate layer between the metal ball and the layer of solder, wherein the intermediate layer is distinct from both the metal ball and the layer of solder and is configured to prevent formation of an intermetallic compound between the metal ball and the layer of solder.

A solder ball for coupling circuit components, comprising:

• a metal ball made of non-solder material;
• a layer of solder over a surface of the metal ball;
• and
• an intermediate layer between the metal ball and the layer of solder, wherein the intermediate layer is distinct in composition from both the metal ball and the layer of solder.