Abstract: A magnetically-assisted chip assembly unit for assembling at least one chip having a mounting surface and an attachment surface, wherein the attachment surface supports a magnetisable layer thereon and opposes said mounting surface, onto a substrate that has a corresponding chip mounting surface. The unit comprises a template wafer having at least one recess adapted to accommodate therein said chip; and a master wafer having at least one magnetisable element; wherein the template wafer is mounted on the master wafer and said magnetisable element is located at least proximate to the at least one recess such that the magnetisable element is capable of manipulating the chip into the recess, via its magnetisable layer when the magnetisable element is magnetized and generates a magnetic field. Once in the recess, the attachment surface of the chip faces at least a portion of the recess and the mounting surface of the chip faces an opening of the recess.

Abstract: We disclose a technique to generate stretched solder columns (bumps) at the wafer level, suitable for wafer level packaging. This is accomplished through use of using two wafers—the standard (functional) wafer that contains the integrated circuits and a master (dummy) wafer on whose surface is provided an array of solder bumps that is the mirror image of that on the functional wafer. After suitable alignment, both sets of solder bumps are melted and then slowly brought together till they merge. Then, as they cool, they are slowly pulled apart thereby stretching the merged solder columns. Once the latter have fully solidified, they are separated from the master wafer only.