A leadless plastic chip carrier is constructed by half etching one or both sides of the package design onto a leadframe strip so as to create unique design features such as power and/or ground ring surrounding the die attach pad, interlocking rivet head construction for the contact pads, and an interlocking...http://www.google.se/patents/US6989294?utm_source=gb-gplus-sharePatent US6989294 - Leadless plastic chip carrier with etch back pad singulation
