CORE METAL SOLDERING KNOB FOR FLIP-CHIP TECHNOLOGY

摘要

The invention relates to a soldering knob with an inhomogenous material composition, especially for the connection of metallised contact surfaces of different electronic components or substrates in flip-chip technology, and a process for producing it. According to the invention, knobs of solder consist of a high-melting-point core (5) determining distance and a layer (6) applied thereto, preferably of a low-melting-point solder material. Thus all the requirements for soldering, like solder deposit, bump height and soldering temperature, are united in the soldering knob of the invention. The low-melting-point solder material also makes it possible to reduce the bonding forces and self-adjustment in the molten state during soldering. The application of the knob core material and the solder in the software-controlled mechanical bumping process is extremely flexible and permits the rapid and low-cost production of flip-chip-bonded prototypes and short runs. The invention particularly obviates the need for cost-intensive and technologically troublesome solder deposition on the substrate and this has the further advantage that the planarising step on the substrate solder knobs is no longer necessary.