Fabrication of Free Floating Circuitry
Original Publication Date: 1980-Nov-01
Included in the Prior Art Database: 2005-Feb-14
Integrated circuit devices normally have an integrated circuit chip mounted on a substrate. Multiple connections are provided between the integrated circuit chip and circuitry on the substrate. One technique of making these connections is controlled collapse solder balls which provide ductility and self-aligning. Since the expansion characteristics of the integrated circuit differ from the expansion characteristic of the circuitry, thermal mismatches naturally occur, thereby placing the solder balls under mechanical stress. These stresses can be minimized by having the integrated circuit chip and the circuitry on the substrate free floating, that is, not attached to the substrate. Such a device can be fabricated in a number of different ways.