A method of soldering can include: providing a first electronic component having a first buttoned soldering pad including a first soldering pad and one or more first button heads protruding from a first surface of the soldering pad; providing a second electronic component having a soldering pad; and soldering the first buttoned soldering pad to the soldering pad. The device structure includes a substrate, a first electrode, a second electrode, and a graded-stoichiometry insulating, or tunnel-barrier, layer formed between the first electrode and the second electrode. The current-sharing control terminal provides a current-sharing control interface. User perceived quality of voice data is derived from the at least one objective measurement.