Abstract: Apparatus and methods for placing conductive spheres on prefluxed bond pads of a substrate using a stencil plate with a pattern of through-holes positioned over the bond pads. Conductive spheres are placed in the through-holes by a moving feed mechanism and the spheres drop through the through-holes onto the bond pads. In one embodiment, the feed mechanism is a sphere hopper which crosses the entire though-hole pattern. In another embodiment, a shuttle plate fed spheres from a reservoir and reversibly moves about one-half of the pitch, moving from a non-discharge position to a discharge position.

Abstract: A memory cell provides point defect trap sites in an insulator for storing data charges. Single electrons are stored on respective point defect trap sites and a resulting parameter, such as transistor drain current, is detected. By adjusting the density of the point defect trap sites, more uniform step changes in drain current are obtained as single electrons are stored on or removed from respective trap sites. By also adjusting the trapping energy of the point defect trap sites, the memory cell provides either volatile data storage, similar to a dynamic random access memory (DRAM), or nonvolatile data storage, similar to an electrically erasable and programmable read only memory (EEPROM). The memory cell is used for storing binary or multi-state data.