Precision Micro Assembly Laboratory

Microscopic machines are the focus of the Precision Micro Assembly Laboratory. Created to investigate the automated assembly of microelectromechanical systems (MEMS) components, the laboratory is developing technologies for a robotic workcell that can assemble MEMS parts 10 to 100 microns in size — about the diameter of a human hair — into tiny machines for use in weapons components, surveillance devices, and microsurgery.

Currently, one of the major limiting factors in micromachine technology is the assembly process. Manual assembly is prohibitively expensive, and the required precision, operator stress, and eye strain associated with assembling such minute parts under a microscope make it impractical. The Precision Micro Assembly Lab is developing technologies that will make such assembly easier and more cost effective, thereby enabling practical applications for micromachines.

In this laboratory, Sandia researchers have made great strides in developing a fully automated CAD-driven workcell for assembling LIGA (Lithographie Galvanoformung Abformung) parts with 100 micron outer dimensions and 1-5 micron tolerances. Fourier optics methods are used to generate synthetic microscope images from CAD drawings. These synthetic images are used off-line to test image processing routines under varying magnifications and depths of field. They also provide reference image features which are used to visually servo the part to the desired position. Currently, the robot can visually servo a 100 micron outside diameter LIGA gear to a desired x,y reference position as determined from a synthetic image of the gear.

Sandia National Laboratories researchers are also working on a parallel means of assembly where multiple gears can be placed on multiple posts in a single step. In this situation, a pin insertion tool press fits several 380 micron diameter pins into holes on a single wafer. This wafer is then mated to another wafer which holds multiple gears. The sandwiched wafers are removed from the workcell and place in an etching bath where the gears are released from the second wafer. This process can be repeated to form gear trains and other complex mechanical structures.

Features

• State of the art motion control equipment including a robotic workcell with 40 nanometer positioning resolution
• Long working distance microscopes
• Laser interferometer equipment
• Micro-tweezers and actuators
• Real-time computer vision to control servo mechanisms and motors for the alignment and assembly of parts with sub-micron tolerances
• Portable class 100 clean room

Collaboration

In optoelectronics and optomechanics manufacturing, precision optical and mechanical assembly of increasingly small devices is a critical technology that will enable U.S. industrial competitiveness. The Precision Micro Assembly Lab is available for collaborative research in such manufacturing applications as fiber optic alignment, integrated circuit assembly, and assembly of other computer related devices. In addition to manufacturing, micromanipulation has potential applications in microbiology and microsurgery.