Substrate having undercut portion for stress mitigation

A device, comprising:

• a substrate comprising a first surface and an opposing second surface;
• a curved surface configured to receive solder material, the curved surface exposed at the first surface of the substrate;
• a solder resist material that at least partially covers the curved surface such that a middle portion of the solder receiving curved surface is exposed and such that an edge portion of the curved surface is covered by the solder resist material and forms an undercut;
• and
• wherein the solder material is disposed within the curved surface and within the undercut.

An electronic device, comprising:

• a cavity disposed in a substrate such that the substrate has a first top surface positioned above the cavity and a second top surface positioned within the cavity;
• an inner substrate wall surrounding the second top surface so as to define the cavity;
• and
• a substantially looped conductive trace disposed in the substrate such that an inner substantially looped portion of the substantially looped conductive trace is disposed on the second top surface and an outer substantially looped portion of the substantially looped conductive trace is enclosed within the substrate under the inner substrate wall.