| abstract |
A package structure is provided. The package structure includes a first bump structure formed over a substrate, a solder joint formed over the first bump structure and a second bump structure formed over the solder joint. The first bump structure includes a first pillar layer formed over the substrate and a first barrier layer formed over the first pillar layer. The first barrier layer has a first protruding portion which extends away from a sidewall surface of the first pillar layer, and a distance between the sidewall surface of the first pillar layer and a sidewall surface of the first barrier layer is in a range from about 0.5 μm to about 3 μm. The second bump structure includes a second barrier layer formed over the solder joint and a second pillar layer formed over the second barrier layer, wherein the second barrier layer has a second protruding portion which extends away from a sidewall surface of the second pillar layer. |