Cold Spray Tool

About

Summary: Scientists working at NDSU have designed a novel cold spray tool and process that is able to direct write metallic lines using metallic powder precursors in small, well defined areas.  This can be done at high deposition rates with features as small as 10 microns possible. In the early 1980s, it was observed that, if a particle in a flow impacted a surface above a certain critical velocity, the particle would undergo plastic deformation and adhere strongly to the surface. This concept was developed and led to the commercialization of the traditional cold spray process. Until now, the cold spray deposition process has been used as a surface coating method, but the process has not yet been used as a direct write process for microelectronic applications. NDSU’s use of cold spray as a direct write technology (called “micro cold spray”) has several advantages over existing direct write technologies. The metal powders can be deposited on rigid as well as flexible substrates without the need for post-processing, making it suitable for use on low temperature substrates. Alternatives to expensive metal powders like gold and silver can be used, including copper, aluminum, and tin. There is no shrinkage of the deposited features, since no solvents are used during the deposition process. The same deposition process can be used for printing interconnects as well as via hole filling.   Benefits: No need for sintering or further post processing, with excellent conductivity. Deposits fine metallic features at only slightly elevated temperatures. Since no solvents are used in deposition, no feature shrinkage occurs. Enables use of less expensive metal powders.   Applications: Solar cell applications, for the direct write of the top metallization layer. Writing interconnects in microelectronics for flexible or printed electronics. Embedded sensor applications.