Note: Descriptions are shown in the official language in which they were submitted.
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SINGLE ACTION ASSEMBLY FOR OUT-OF-PLANE MEMS MICROSTRUCTURES
TECHNICAL FIELD
The invention applies to surface micromachined structures. In particular, the
invention
relates to a method for assembling out-of-plane structures and related
apparatus.
BACKGROUND
Surface micromachined Micro-Electro-Mechanical Systems (MEMS) devices are
fabricated in-plane. In order to create out-of-plane devices, the MEMS
microstructures
require assembly.
Micromanipulator probes are a well established tool in the microelectronics
industry for
precisely positioning probe-tips for measuring, powering, actuating, and
positioning
micro-structures.
The wire-bonder is a well established tool in the microelectronics industry
for the
automation of creating wire contacts between an integrated circuit and the
electronic
package. The precision of the bonder is highly accurate and is robotically
controlled.
A simple and rapid method of assembly using the micromanipulator probe or wire-
bonder
is desired for assembling out-of-plane microstructures.
SUMMARY OF THE INVENTION
The invention relates to a mechanical design that allows the out-of-plane
assembly of
surface micromachined structures manufactured on a substrate. The substrate
is, for
example, a silicon wafer or chip.
The method of the invention involves manufacturing any device that requires
out-of-
plane assembly with spring flexures that are more compliant in-plane than out-
of-plane.
By applying a lateral force in one dimension using a tool such as the
micromianipulator
or wire-bonder, the spring flexures naturally rotate and lock the device out-
of-plane using
friction [FIG 1 and FIG 2] or with a combination of a locking mechanism [FIG 3
to FIG
7].
The angle of the device to the substrate can be selectively designed by
modifying the
location of the locking mechanism.
The number of linkages and dimensions of the spring flexures are not limited
in the
invention. Depending on the material or application, the dimensions and number
of
linkages can be modified to suit the application.
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Using the micromanipulator or an automated wire-bonder in combination with a
lateral
force, microstructures using this design can be rapidly assembled.
BRIEF DESCRIPTION OF THE DRAWINGS
In figures which illustrate non-limiting embodiments of the invention:
FIG 1 is an example of the basic design for single action out-of-plane
assembly with a
two loop spring linkage.
FIG 2 is an example of the basic design using a triangular spring flexure.
FIG 3 is an example of the design in FIG 1 including the locking mechanism
FIG 4 is an example of the design in FIG3 with a variation of the locking
mechanism
FIG 5 is an example of the design in FIG3 with a variation of the locking
mechanism
FIG 6 is an example of the design in FIG3 with a variation of the locking
mechanism
FIG 7 is an example of the design in FIG3 with a variation of the locking
mechanism
FIG 8 is the diagram of the design in FIG7 assembled out-of-plane
FIG 9 is a scanning electron microscope image of an example of a
microstructure rotated
out-of-plane using the loop spring linkage and held in place by friction
FIG 10 is a scanning electron microscope image of an example of a
microstructure
rotated out-of-plane using the loop spring linkage and held in place by
friction
FIG 11 is a scanning electron microscope image of an example of a
microstructure
rotated out-of-plane using the loop spring linkage and held in place by
friction
FIG 13 is a scanning electron microscope image of an example of a
microstructure
rotated out-of-plane using the loop spring linkage and held in place by
friction
FIG 14 is a scanning electron microscope image of an example of a
microstructure
rotated out-of-plane using the triangular flexure spring and held in place by
friction
FIG 15 is a scanning electron microscope image of an example of a
microstructure
rotated out-of-plane using the triangular flexure spring and held in place by
friction
FIG 16 is a scanning electron microscope image of an example of a
microstructure
rotated out-of-plane using the triangular flexure spring and held in place by
friction
FIG 17 is a scanning electron microscope image of an example of a
microstructure
rotated out-of-plane using the triangular flexure spring and held in place by
friction
FIG 18 is a scanning electron microscope image of an example of a
microstructure
rotated out-of-plane using the loop spring linkage and held in place by
friction
FIG 19 is a photograph of an example of a microstructure rotated out-of-plane
using the
loop spring linkage and held in place by friction
FIG 20 is a photograph of an example of a microstructure rotated out-of-plane
using the
loop spring linkage and held in place by friction
FIG 21 is a photograph of an example of a microstructure rotated out-of-plane
using the
loop spring linkage and held in place by friction
FIG 22 is a photograph of an example of a microstructure rotated out-of-plane
using the
loop spring linkage and held in place by friction
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FIG 23 is a set of photomicrographs showing the assembly sequence for the two
loop
spring linkage design.
DETAILED DESCRIPTION
Throughout the following description, specific details are set forth in order
to provide a
more thorough understanding of the invention. However, the invention may be
practiced
without these particulars. In other instances, well known elements have not
been shown
or described in detail to avoid unnecessarily obscuring the invention.
Accordingly, the
specification and drawings are to be regarded in an illustrative, rather than
a restrictive,
sense.
The invention relates to a mechanical design that allows for the out-of-plane
assembly of
surface micromachined structures manufactured on a substrate. The substrate
is, for
example, a silicon wafer or chip.
The method of the invention involves manufacturing any device that requires
out-of-
plane assembly with spring flexures that are more compliant out-of-plane than
in-plane.
The typical aspect ratio of the width of the spring flexures to its thickness
is
approximately 3:1. However, depending on the material properties or
application, the
aspect ratio can be modified to suit the need.
By applying a lateral force using a tool such as the micromianipulator probe-
tip or wire-
bonder on the bottom edge of the device along the plane, the spring flexures
naturally
rotate and lock the device out-of-plane using friction between the bottom edge
and the
substrate [FIG 1 and FIG 2] or with a combination of a locking mechanism [FIG
3 to FIG
7].
The sequence for assembly can be seen in FIG 23.
The microstructure to be rotated out-of-plane can be attached either to the
top of the
device or underneath in the case where a cavity in the substrate exists.
Examples of
microstructures utilizing the invention are shown in FIG 9 to FIG 22.
The angle of the device to the substrate can be selectively designed by
modifying the
location of the locking mechanism.
The number of linkages and the dimensions of the spring flexures are not
limited in the
invention. Depending on the material used or application, the dimensions and
number of
linkages can be modified to suit the application.
Using the micromanipulator or an automated wire-bonder in combination with a
lateral
force, microstructures using this design can be rapidly assembled.
As will be apparent to those skilled in the art in the light of the foregoing
disclosure,
many alterations and modifications are possible in the practice of this
invention without
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departing from the spirit or scope thereof. Accordingly, the scope of the
invention is to be
construed in accordance with the substance defined by the following claims.
