Production of microelectronic components by electrophoretic deposition

Electrophoretic deposition (EPD) is a particle based, electrodynamic forming process suitable for particles in the micron to nanometer size range. Beginning with a 300 nm diameter silver/palladium powder we have used EPD to produce 5 mum wide conductor lines with a 10 mum spacing on a dielectric tape. In this process a component is first imaged as a conductive pattern on a plastic film by conventional photolithography. This pattern is then immersed into a stable, dispersed and electrostatically charged suspension of particles. A voltage is applied between the conductive pattern and a counter electrode in the suspension, causing a current flow through the suspension, and attracting particles to the conductive pattern. The current creates an electro-chemical environment at the surface which causes the particles to deposit onto the pattern. This deposition can range from a monolayer to many thousands of particles thick. Using a binder, these deposited particles can then be transferred to another surface to be sintered or fused forming continuous lines or layers. The photolithographically produced conductor pattern can be re-used repeatedly to create more depositions. In this manner a single pattern produced by photolithography can be used to make multiple parts with photolithographic scale resolution.