By Neil Sarkar, Zyvex Corporation
Download a printable copy here.
Zyvex has developed a unique microassembly technology to integrate heterogeneous
micro and nano components into real-world three-dimensional structures and
devices. This application note is intended to familiarize the reader with
this powerful new technology, and to demonstrate how it tackles a broad range
of difficult microassembly challenges. The methods we present are particularly
suitable for intricate mechanisms consisting of precisely manufactured micro-components
that require high accuracy assembly.
Using proprietary MEMS (microelectromechanical systems) and NEMS (nanoelectromechanical
systems) libraries of end-effectors, handles, connectors, and sockets, we routinely
achieve positional accuracies better than 100 nm over lengths of several centimeters,
for a large number of components in an automated process.
As previously mentioned, the technology described here is
suitable for real-world applications such as high precision
alignment, high precision automated mechanical assembly,
and other industrial applications where high precision assembly
is desirable.
Our current micromanipulation capabilities rely on a closed-loop, automated
5 DOF (degree-of-freedom) robotic pick and place system with 25 nm positional
accuracy, used to assemble microcomponents with minimum feature sizes better
than 500 nm. A schematic depiction and a photograph of this system are shown
in Figure 1.
Figure
1: (a) Schematic depiction of the Zyvex MEMbler. (b)
The photograph shows the actual 5 DOF automated microassembly
system with 25 nm positioning accuracy and closed-loop feedback.
Figure 2 shows one example of a microassembled device; a
miniature electron beam column intended for use in a benchtop
scanning electron microscope (SEM). This device consists
of several lenses and deflectors that are assembled using
proprietary connectors providing robust mechanical connectivity,
as well as low-resistance electrical routing for column operation
with high voltages.
Figure 2: A miniature electron beam steering
column microassembled using Zyvex technology. Robust mechanical
and electrical
interconnects are used to assemble an array of patterned
silicon “electron lenses” with sub-micron accuracy
over a length of several centimeters.
The automated assembly procedures can
make use of various types of end-effectors, articulated by
the MEMbler.
Active end-effectors, like Zyvex microgrippers,1 and
passive end-effectors2 have both been implemented.
A typical series of steps involved in microgripper-based
assembly3 is shown in Figure 3,
along with an example of a device assembled using this technique.
This device was
assembled using the Zyvex A100 Nanomanipulator System as
well as Zyvex NanoEffector™ Microgrippers.*
* Zyvex Corporation offers a wide
range of accessories for the A100 Nanomanipulator, including
NanoEffector™ Microgrippers
and Probes.
For more information, contact Zyvex at 877.998.3999
ext. 271 or email sales@zyvex.com.
Figure 3: Heterogeneous microassembly of
a tunable inductor. Components are (a) grasped, (b) manipulated
with actuated
grippers, and (c) secured in place with connectors and/or
adhesives. (d) This device includes a copper electroplated
solenoid inductor, a MEMS linear stepping stage, and a high
permeability magnetic core; all are integrated using gripper-based
techniques.
A typical series of assembly steps that are executed in
the passive end-effector technique2 is illustrated below
in Figure 4. A micromachined round tip is inserted into
a handle with built-in compliance. The friction forces
allow the device to be securely held in place during the
ensuing micromanipulation step.
Figure 4 (a) Assembly sequence with a passive end-effector.
Friction forces allow the end-effector to mate with a component
that has built-in compliance in its connector. This connector
is then inserted into a compliant socket and is snapped into
place, held rigidly by stiff silicon beams. (b) Heterogeneous
assembly of a VOA (Variable Optical Attenuator). Fiber optic
cable, ball lens, and rotating micromirror are shown here.
Components with integrated connectors are inserted into
specially designed sockets on the assembly substrate. The
component is lowered into this socket, deforming a built-in
spring until it snaps into place. The assembled component
is now rigidly held in place by self-centering
spring forces, and electrical routing can be implemented
through the flat contact areas. Figure 4 also
shows an assembled micromirror that is rotated by thermal
actuators — this
is an example of an actuated socket, which allows for active
micropositioning of the assembled object.4 The
resonant frequencies of these assemblies have been measured
at over 1 kHz.5
Cascaded microassemblies using passive end-effectors in an
automated process are currently under development. Figure
5 shows a three-component assembly of palettes that are
designed to mate with the passive end-effector.
Figure 5: Cascaded microassembly using the
passive end-effector.
Zyvex MEMulator™ simulation of
a component being (a) placed,
(b) inserted, and (c) released. (d) SEM image of the completed
microstructure.
Active and passive end-effectors have been used to assemble
complex three-dimensional structures using serial arrangements
of multiple connectorized devices. Zyvex MechTiles™ are
palettes with sockets and connectors that can be assembled
in such a cascaded fashion, as illustrated in Figure
6.
Figure 6 Cascaded microassembly using MechTiles™.
Over 20 components
have been assembled in a single 3-D microstructure.
Complex microassemblies with minimum features sizes down
to 500 nm and submicron positional accuracies over centimeter-distances
are routinely manufactured using the methods described
here. Precise mechanisms of hetero-geneously assembled
micro-components are good candidates for the techniques
presented here.
The microassembly technology at Zyvex has been
developed for over 5 years and supported with over $15 million
in research
funding. A dedicated staff of over 15 scientists and engineers
has designed, fabricated and characterized a large number
of assembled devices and systems.
This technology is now available for applications ranging
from telecom to life sciences to nanotechnology instrumentation.
Zyvex provides turnkey microassembly solutions, microassembled
device designs, and access to our microassembly toolkit
libraries. Contact Dr. John Randall, Zyvex’s Chief
Technical Officer, at 972-235-7881 (ext. 248) to find out
how we can apply this unique and versatile technology to
assist you with your microassembly challenges.
The work presented in this application
note is supported through our NIST-ATP (National Institute
of Standards and
Technology - Advanced Technology Program) 5-year, $25 million
grant entitled, “Assemblers for Nanotechnology Applications
and Manufacturing: Enabling the Nanotechnology Era.” This
work is also supported by a DARPA SBIR grant awarded to
Zyvex entitled, “Manufacturing Assembly Technology
for Producing Low-Cost Mini SEM Columns.”
1. K. Tuck, et al, “Using Microgrippers with the S100,” Zyvex
Application
Note 9703.
2. K. Tsui, “Micromachined end-effector and techniques for directed MEMS
assembly,” Journal of Micro Mechanics andMicroengineering, 14 (2004)
542-549.
3. G. Skidmore, et al, “Assembly technology across multiple length scales
from the micro-scale to the nano-scale,” Proceedings of the 17th IEEE
International Conference on Micro Electro Mechanical Systems, 588-592.
4. R. Saini, et al, “Assembled MEMS VOA,” IEEE LEOS 2003, International
Conference on Optical MEMS and their Applications, 18-21 August 2003.
5. Z. Jandric, et al, “Modal Analysis of Assembled MEMS,” 11th
International Microelectronics and Packaging Society (IMAPS). Boxborough, MA,
May 6 (2004).
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