| abstract |
A method for manufacturing an electronic module comprising a substrate carrying circuitry and one or more integrated circuits and having an array of closely spaced solder balls electrically connected with terminals of the circuitry to connect the module to an array of terminals, as on printed circuit board. The array of solder balls is fabricated on the substrate by preparing the substrate to include an array of terminal pads, perforating a sheet of dielectric tape to create precise and uniform holes, and thereafter fusing the tape onto the substrate so that the holes are aligned over the substrate's terminal pads. Solder balls are then placed in the holes and heated to reflow them, so that part of the solder fills a volume defined by the holes in the dielectric tape and bonds to the terminal pads on the substrate, while the solder balls remain generally spherical above the dielectric tape. The module can then be connected to an array of terminal pads on a circuit board by positioning the ball grid array on the circuit board and again reflowing the solder balls so that they bond with the terminal pads on the circuit board. |