Micro-scale force-fit insertion

Abstract

-Several LIGA (Lithography Galvonoforming Abforming) test mechanisms have been designed and fabricated to study tribology and performance attributes of LIGA mechanisms. The LIGA test mechanism studied in this paper is a ratchet drive mechanism consisting primarily of pawls, cams, and springs ranging in size from about one-half millimeter to tens of millimeters of various nickel alloys fabricated using the LIGA process. To assemble the test mechanism, subassemblies are made by inserting force-fit pins into stacks of piece-parts. These pins are cut from 170µm wire and range from 500 to 1000µm in length. Human insertion of these pins is extremely difficult due to their small size and tolerances required to perform the force-fit operation. This paper describes the tooling to permit fabrication, bulk handling, and force-fit insertion of pins with the operator-guided automation required to achieve micron-scale tolerances using hybrid force/position control algorithms.

Development of a virtual and physical work cell to assemble micro-devices

“…Jones et al [11] presented a study in the assembly of Lithography Galvonoforming Abforming (LIGA) ratchet drive mechanisms consisting of pawls, cam, and springs, ranging in size from about one-half millimeter to tens of millimeters. These mechanisms are assembled by using pins cut from 170 mm wire ranging in length from 500 to 1000 mm.…”

“…This latter node translates or rotates the part specified in the Transform node (and mentioned in the input file by the user) from initial to final position or orientation respectively [11]. A view of virtual cell is shown in Fig.…”

Design of a Piezoresistive Surface Micromachined Three-Axis Force Transducer for Microassembly

“…A variety of techniques have been developed to facilitate such assembly processes, including the use of microrobotic work cells that utilize methods from traditional robotic manufacturing [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Visual feedback techniques may be well suited to the assembly of MEMS components in which small lot sizes and diverse parts makes traditional fixturing infeasible [8].…”

“…Whitney outlines the forces and reactions experienced during this type of assembly task that can be characterized by a force in the z-direction, and moments about the x and y axes [20]. Typical reaction forces produced during microassembly can range from mN to µN [7].…”

Real-time three-dimensional visualization of standard light microscope image sequences for microassembly

“…Figures 8a-e show some of the 25 slices, Figure 8f shows a volume rendering recreating the original view with increased depth of field and Figures 8g -h show two additional views of the z-volume. These images show a pair of tweezers in front of a LIGA micropart (for a description of the assembly procedure used with this micropart, see [4]). It can be seen that, even though the tweezers occlude a portion of the micropart, the occluded portions of the micropart are rendered correctly in the volume renderings.…”