A novel flip‐chip interconnection process for integrated circuits

Purpose The purpose of this paper is to present an outline of the development of a new process for the formation of flip‐chip interconnections using metal coated polymer microparticles. Design/methodology/approach Metal coated polymer microparticles were selectively deposited onto the bondpads of integrated circuits using electrophoresis. Thermocompression bonding was then used to bond the devices to substrates. Findings Particles obtained a positive surface charge following immersion in an acidic solution and this surface charge allowed the particles to be deposited electrophoretically directly onto the bondpads of an integrated circuit without the need for patterning. Thermocompression bonding of nickel/gold coated particles to gold coated substrates was achieved at temperatures as low as 160°C. Research limitations/implications Further work is needed to test this approach using integrated circuits with finer pitch, and to use patterned substrates for assembly and reliability measurements. Originality/value This paper presents a new method for the deposition of metal coated polymer microparticles without the need for any masking or patterning processes for the formation of interconnections on integrated circuits.