Electronic assemblies and their manufacture are described. One embodiment relates to a method including depositing an organic thin film layer on metal bumps on a semiconductor wafer, the organic thin film layer also being formed on a surface adjacent to the metal bumps on the wafer. The wafer is diced into a plurality of semiconductor die structures, the die structures including the organic thin film layer. The semiconductor die structures are attached to substrates, wherein the attaching includes forming a solder bond between the metal bumps on a die structure and bonding pads on a substrate, and wherein the solder bond extends through the organic thin film layer. The organic thin film layer is then exposed to a plasma. Other embodiments are described and claimed.

The present disclosure relates to a substrate structure with selective surface finishes used in flip chip assembly, and a process for making the same. The disclosed substrate structure includes a substrate body, a metal structure with a first finish area and a second finish area, a first surface finish, and a second surface finish. The metal structure is formed on a top surface of the substrate body, the first surface finish is formed over the first finish area of the metal structure, and the second surface finish is formed over the second finish area of the metal structure. The first surface finish is different from the second surface finish.