A solder connection may be surrounded by a solder locking layer (1210, 2210) and may be recessed in a hole (1230) in that layer. The recess may be obtained by evaporating a vaporizable portion (1250) of the solder connection. Other features are also provided.

A solder connection may be surrounded by a solder locking layer (1210, 2210) and may be recessed in a hole (1230) in that layer. The recess may be obtained by evaporating a vaporizable portion (1250) of the solder connection. Other features are also provided.

An integrated circuit (IC) die structure comprises a substrate material comprising silicon. Integrated circuitry is over a first side of the substrate material. A composite layer is in direct contact with a second side of the substrate material. The second side is opposite the first side. The composite layer comprises a first constituent material associated with a first linear coefficient of thermal expansion (CTE), and a first thermal conductivity exceeding that of the substrate. The composite layer also comprises a second constituent material associated with a second CTE that is lower than the first, and a second thermal conductivity exceeding that of the substrate.