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 µm wide conductor lines with a 10 µm 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 electrochemical 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.