Micro-Selective Laser Sintering System
Physical Sciences : Electrical
Available for licensing
- Michael Cullinan, Ph.D. , Mechanical Engineering, Cockrell
- Nilabh Roy , NXP Semiconductor Inc.
- Anil Yuksel , NXP Semiconductors N.V. (fka Freescale Semiconductor, Inc.)
- Chee Seng Foong , NXP Semiconductor Inc.
The smallest feature sizes that commercially available sintering machines can achieve is of the order of hundreds of microns, and this system has been designed to achieve 1μm feature sizes with metals. To get that feature size, it is necessary to use particles smaller than the feature size; hence, NPs were the first choice for the sintering. Since they have a very high surface-area-to-volume ratio, oxidation becomes unavoidable in contact with air; thus, a high vacuum is required for sintering the powders.
Traditionally, the spreading mechanism consisted of a counter-rotating roller which would sweep across the powder bed spreading powder layer by layer, but with the problem of agglomeration and very low density of nanopowders, this study presents a spreader design which consists of two stages to overcome the agglomeration effects and spread the powder uniformly in a layer.
Techniques like two photon (or multi-photon) polymerization can achieve such resolution with polymers but their throughput is very low.
A novel approach has been developed to produce 3D structures with micron-sized features (can be scaled down to sub-micron features) with metals. The selective laser sintering system primarily consists of: (a) a nanosecond laser used to sinter the metal nano-particles and minimize the heat affected zone (b) a DLP chipset in conjunction with a focusing objective lens to focus the laser down to a micron spot size and illuminate a maximum of as many spots as there are mirrors on the DLP (786432 with CEL5500), (c) a build stage on a one degree-of-freedom nano-positioning system which can be moved with a resolution of 40nm, (d) a two-stage powder spreading system used to produce an even layer of powder for each build step, (e) a vacuum chamber used to control the build atmosphere, and (f) several in-situ metrology systems used to characterize the build process including a high-speed IR thermal camera and near-field scanning optical microscope.
The invention has potential applications in electronics (packaging of micro-electronics), biomedical, automotive, aerospace and defense industries.
Proof of concept
- 1 U.S. patent application filed