Semiconductor devices, methods of manufacture thereof, and packaged semiconductor devices are disclosed. A method of forming a device includes forming a conductive trace over a first substrate, the conductive trace having first tapering sidewalls, forming a conductive bump over a second substrate, the conductive bump having second tapering sidewalls and a first surface distal the second substrate, and attaching the conductive bump to the conductive trace via a solder region. The solder region extends from the first surface of the conductive bump to the first substrate, and covers the first tapering sidewalls of the conductive trace. The second tapering sidewalls of the conductive bump are free of the solder region.