U.S. patent application number 12/068578 was filed with the patent office on 2009-07-23 for self-assembly micro blade.
This patent application is currently assigned to Sunonwealth Electric Machine Industry Co., Ltd.. Invention is credited to Alex Horng, Chung-Jen Huang, I-Yu Huang.
Application Number | 20090185909 12/068578 |
Document ID | / |
Family ID | 40876633 |
Filed Date | 2009-07-23 |
United States Patent
Application |
20090185909 |
Kind Code |
A1 |
Horng; Alex ; et
al. |
July 23, 2009 |
Self-assembly micro blade
Abstract
The present invention relates to a self-assembly micro blade
applied to a micro fan. The micro fan combines at least a
self-assembly micro blade and a motor using an actuator as the main
body of the micro fan. The self-assembly micro blade includes at
least a movable part of a microstructure, at least an elastic joint
provided between an outer ring of the micro fan and the movable
part. The elastic joint is composed of a polyimide film, which is
heated to contract and generate surface tension by using a reflow
process so as to lift up the movable part of the microstructure;
moreover, the movable part is bent in a curved form through the
elastic link exhibits a multi-layer shape by serially connecting at
least two movable parts so as to complete the self assembly of the
micro blade, thereby increasing air flow rate and improving air
flow length.
Inventors: |
Horng; Alex; (Kaohsiung
City, TW) ; Huang; I-Yu; (Kaohsiung City, TW)
; Huang; Chung-Jen; (Kaohsiung City, TW) |
Correspondence
Address: |
BACON & THOMAS, PLLC
625 SLATERS LANE, FOURTH FLOOR
ALEXANDRIA
VA
22314-1176
US
|
Assignee: |
Sunonwealth Electric Machine
Industry Co., Ltd.
Kaohsiung City
TW
|
Family ID: |
40876633 |
Appl. No.: |
12/068578 |
Filed: |
February 8, 2008 |
Current U.S.
Class: |
416/220R |
Current CPC
Class: |
F05D 2230/31 20130101;
F05D 2300/434 20130101; F04D 29/281 20130101; F04D 25/0613
20130101; F04D 29/30 20130101; F05D 2300/437 20130101; F04D 29/023
20130101 |
Class at
Publication: |
416/220.R |
International
Class: |
B63H 1/20 20060101
B63H001/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 22, 2008 |
TW |
97102285 |
Claims
1. A self-assembly micro blade, comprising: at least a movable part
of a microstructure; at least an elastic joint provided between the
movable part and an outer ring of a micro motor, and generating
surface tension to lift up the movable part of the microstructure
by using a reflow process.
2. The self-assembly micro blade as set forth in claim 1, wherein
the elastic joint is a photosensing polyimide film.
3. The self-assembly micro blade as set forth in claim 1, wherein a
method for manufacturing the self-assembly micro blade comprises
processes of: (1) depositing a low-stress sacrifice layer on a
silicon substrate and depositing a main structure layer on the
low-stress sacrifice layer; (2) defining the main structure layer
to etch out an overall profile of the microstructure; (3) coating a
photosensing polyimide film on the main structure layer and an
outer ring of the micro motor; (4) defining the polyimide film to
etch out a form of an elastic joint; (5) performing wet etch to
etch and release a preset portion of the low-stress sacrifice
layer; and (6) performing a reflow process to heat up the elastic
joint to result in thermal contraction and lifting up a preset
portion of the main structure layer.
4. The self-assembly micro blade as set forth in claim 3, wherein
the low-stress sacrifice layer is a phosphosilicate glass
(PSG).
5. The self-assembly micro blade as set forth in claim 3, wherein
the main structure layer is a polysilicon.
6. A self-assembly micro blade, comprising: at least a movable part
of a microstructure; and at least an elastic joint provided between
the movable part and an outer ring of a micro motor; and an elastic
link provided on each movable part, so that surface tension is
generated by each of the elastic joint and the elastic link through
a reflow process and the movable part of the microstructure is
lifted up and bent in form of curved surface;
7. The self-assembly micro blade as set forth in claim 6, wherein
the elastic joint is a photosensing polyimide film.
8. The self-assembly micro blade as set forth in claim 6, wherein a
first elastic joint is defined on a first side of the movable
part.
9. The self-assembly micro blade as set forth in claim 6, wherein a
second elastic joint is defined on a second side of the movable
part.
10. The self-assembly micro blade as set forth in claim 6, wherein
an elastic link is defined above the first elastic joint on each of
the movable part.
11. The self-assembly micro blade as set forth in claim 6, wherein
a third elastic joint is defined above the elastic link on the
movable part.
12. The self-assembly micro blade as set forth in claim 6, wherein
the elastic link is a photosensing polyimide film.
13. A self-assembly micro blade, comprising: at least a first
movable part and a second movable part of a microstructure; and at
least an elastic joint provided between the first movable part and
an outer ring of a micro motor and between the first movable part
and the second movable part respectively; and an elastic link is
provided on each second movable part, so that surface tension is
generated by each of the elastic joint and the elastic link through
a reflow process and the movable part of the microstructure is
lifted up and bent in form of multiple layers and curved plane.
14. The self-assembly micro blade as set forth in claim 13, wherein
the elastic joint is a photosensing polyimide film.
15. The self-assembly micro blade as set forth in claim 13, wherein
a first elastic joint is defined on each of the first movable
part.
16. The self-assembly micro blade as set forth in claim 13, wherein
a second elastic joint is defined on a first side of each of the
second movable part.
17. The self-assembly micro blade as set forth in claim 13, wherein
a third elastic joint is defined on a second side of each of the
second movable part.
18. The self-assembly micro blade as set forth in claim 13, wherein
an elastic link is defined above the second elastic joint of each
of the second movable part.
19. The self-assembly micro blade as set forth in claim 13, wherein
a fourth elastic joint is defined above the elastic link of each of
the second movable part.
20. The self-assembly micro blade as set forth in claim 13, wherein
the elastic link is a photosensing polyimide film.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a self-assembly micro blade
for micro fan, which is characterized by providing additional flow
rate and control and improvement of flow length so as to solve the
drawbacks of conventional skill.
BACKGROUND OF THE INVENTION
[0002] Research and application of miniaturization technology is
one of two major trends of modern science. In particular,
self-assembly technique is a mainstream approach for assembling
microstructure in microworld in recent years.
[0003] As far as a micro fan manufactured by micro
electromechanical systems (MEMS) technology is concerned, a scratch
drive actuator (SDA) and a micro blade structure of the micro fan
could only be built by virtue of self-assembly technique and
multi-user MEMS processes (MUMPs).
[0004] The so-called self-assembly technique means that a
microstructure mechanism self-positions after completing the final
release process. The current self-assembly technique has the
following three types of:
[0005] using the release of residual stress in manufacturing
process to result in deformation enabling microstructure to
displace, e.g. 3D micro optical switch developed by Lucent
Technologies;
[0006] oscillating microstructure to a predetermined position by
using supersonic wave to generate surface wave; and
[0007] first using solder ball, photoresist or other polymer to
produce an elastic joint on a micro hinge, then making the elastic
joint in molten state at high temperature through a reflow process,
and generating surface tension capable of pulling up the
microstructure.
[0008] Whereas, the aforementioned first type and second type of
self-assembly techniques are only applicable to the microstructure
in a static occasion or at a stationary position, making them not
only inappropriate for manufacturing a component with displacing
motion but also inappropriate for manufacturing a micro fan with
rotary motion.
[0009] Furthermore, speaking of the third type of self-assembly
technique, there are a lot of materials for making the elastic
joint. However, different material has its respective advantageous
and disadvantageous characteristics. Here exemplified by lead tin
alloy ball:
[0010] lead pollution: A lead tin alloy ball is a mixture of lead
and tin (63Sn/37Pb); hence, both stage and environment have the
phenomenon of lead pollution during reflow;
[0011] high cost: Most of microstructures are mainly constructed by
poly-silicon; if a lead tin alloy ball needs to be attached
thereon, a layer of gold pad shall be coated on the surface of
poly-silicon to serve as a connection interface between lead tin
alloy balls. Such additional step will result in difficulty while
manufacturing and cost rise.
[0012] poor accuracy: While calculating elevation angle or
displacement value of a microstructure, the ball size shall be
accurately grasped. However, lead tin alloy ball has a volume error
up to 25%, making elevation angle or displacement value hard to be
accurately controlled.
[0013] manual operation: The placement of lead tin alloy ball on
the gold pad still rely on manual alignment operation for the
moment.
[0014] planar lifted microstructure: The microstructure lifted by
elastic joints is limited to take a planar shape and fails to be
curved.
[0015] miniaturization infeasibility: Current size of lead tin
alloy ball is unable to be smaller than 100 .mu.m, making the
smallest size of elastic joint become relatively restrictive.
[0016] Further exemplified by using photoresist as the material of
elastic joint:
[0017] Although the process for using photoresist to manufacture
elastic joint is not as complicated as that for lead tin alloy ball
and the cost is lower, the cantilever release of microstructure
must be performed with dry or wet etch method.
[0018] Dry etch method releases the cantilever of microstructure
and replaces water molecules therein with liquid CO2 to avoid stick
effect of the cantilever. However, the cost of super critical CO2
dry release equipment used by the method is expensive. Thus, the
cost is relatively higher.
[0019] Wet etch method won't require additional manufacturing
equipment, and thus the cost is lower. After using hydrofluoric
acid (HF) or buffer oxide etcher (BOE) solution to etch sacrifice
layer, isopropyl alcohol (IPA) must be applied to quickly vaporize
water molecules so as to release cantilever. However, IPA is
characterized by dissolving photoresist. As a result, the
originally manufactured elastic joint will be destructed.
[0020] In conclusion, based on multiple concerns of cost,
manufacturing process, environmental protection, miniaturization,
planar lifted microstructure and so on, a totally new process
surely needs to be developed to solve various shortcomings arising
from the elastic joint made by lead tin alloy ball or
photoresist.
SUMMARY OF THE INVENTION
[0021] A primary object of the present invention is to provide a
self-assembly micro blade with movable part.
[0022] The present invention pertains to a self-assembly micro
blade applied to a micro fan. The micro fan combines at least one
self-assembly micro blade and a motor using an actuator as the main
body of the micro fan. The self-assembly micro blade includes at
least a movable part of a microstructure, and at least an elastic
joint provided between the movable part and an outer ring of the
micro motor, composed of a polyimide film and generating surface
tension by heating the elastic joint to result in thermal
contraction through a reflow process so as to lift up the movable
part of the microstructure in completion of the self-assembly micro
blade.
[0023] A secondary object of the present invention is to provide a
self-assembly micro blade providing a curved movable part so as to
address increasing air flow rate and control and improved air flow
length.
[0024] The present invention is applied to a self-assembly blade of
a micro fan. The micro fan combines at least a self-assembly micro
blade and a motor using an actuator as the main body of the micro
fan. The self-assembly micro blade includes at least a movable part
of a microstructure, at least an elastic joint provided between the
movable part and an outer ring of the micro motor, and an elastic
link provided on each movable part. The elastic joint and the
elastic link are composed of a polyimide film. By using a reflow
process, the elastic joint and the elastic link are heated to
contract and generate surface tension to lift up the movable part
of the microstructure and form a curved movable part through the
elastic link in completion of the self-assembly micro blade.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a schematic view showing a first preferred
embodiment of a micro blade applied to a micro fan in the present
invention;
[0026] FIG. 2 is a schematic view showing the implementation for
the first preferred embodiment of a micro blade applied to the
micro fan in the present invention;
[0027] FIG. 3 is a schematic view showing steps of manufacturing
processes of the present invention;
[0028] FIG. 4 is a schematic view showing a second preferred
embodiment of a micro blade applied to a micro fan in the present
invention;
[0029] FIG. 5 is a schematic view showing the implementation for
the second preferred embodiment of a micro blade applied to a micro
fan in the present invention;
[0030] FIG. 6 is a schematic view showing a third preferred
embodiment of a micro blade applied to a micro fan in the present
invention; and
[0031] FIG. 7 is a schematic view showing the implementation for
the third preferred embodiment of a micro blade applied to a micro
fan in the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0032] Please refer to FIG. 1 and FIG. 2. The present invention
provides a first type of self-assembly micro blade to achieve a
micro blade structure having movable parts. The self-assembly micro
blade includes at least a movable part 21 of a microstructure, and
at least an elastic joint 31 provided between the movable part 21
and an outer ring 11 of a micro motor. The elastic joint that is a
photosensing ployimide film is heated to contract and generate
surface tension after performing a reflow process in a
high-temperature oven, so as to lift up the movable part of the
microstructure and make the microstructure have a movable part for
elevation while performing self assembly.
[0033] Please refer to FIG. 3. The present invention includes
manufacturing processes of:
[0034] (1) using plasma enhanced chemical vapor deposition method
to deposit a phosphosilicate glass (PSG) on a silicon substrate 60
to serve as a low-stress sacrifice layer 70, and further using low
pressure chemical vapor deposition (LPCVD) to deposit poly-silicon
on the low-stress sacrifice layer as a main structure layer 80.
[0035] (2) performing a first photolithography process to etch the
main structure layer 80 with an inductive couple plasma (ICP)
etching machine so as to etch the main structure layer 80 for
defining an overall profile of the microstructure.
[0036] (3) using a spin coater to coat a photosensing polyimide
film 50 on the main structure layer 80 and an outer ring 11 of a
BDA micro motor;
[0037] (4) performing a second photolithography process to define a
form of an elastic joint 31;
[0038] (5) submerging the microstructure in a buffered oxide etch
(BOE) solution to perform wet etch and etch and release a
predetermined portion of the low-stress sacrifice layer 70; and
[0039] (6) using a high-temperature oven to perform a reflow
process so as to make the elastic joint 31 in molten state at high
temperature and heating the elastic joint 31 to generate thermal
contraction and deformation so as to lift up a predetermined
portion of the main structure layer 80.
[0040] Please refer to FIG. 4 and FIG. 5. The present invention
provides a second type of self-assembly micro blade to achieve a
micro blade structure with curved movable parts. The self-assembly
micro blade includes: at least a movable part 21 of a
microstructure; at least an elastic joint 31 provided between the
movable part 21 and an outer ring 11 of a micro motor; and an
elastic link 315 provided on each movable part 21.
[0041] The elastic joint 31 and the elastic link 315 are composed
of a photosensing polyimide film. Surface tension is generated by
each elastic joint 31 and elastic link 315 through a reflow process
to bend and lift up the movable part 21 of the microstructure.
[0042] The design that elastic joint and elastic link are provided
between each movable part 21 and the outer ring 11 of the micro
motor lies in that a first elastic joint 311 is defined on one side
of each movable part 21, a second elastic joint 312 is defined on
another side of each movable part 21, an elastic link 315 is
defined above the first elastic joint 311 of each movable part 21,
and a third elastic joint 313 is defined above the elastic link 315
of each movable part 21. Given the aforementioned reflow process, a
micro blade with curved movable part can be achieved.
[0043] Please further refer to FIG. 5 showing a design for the
second type of self-assembly micro blade. While performing a reflow
process, each of the elastic joints (311, 312, 313) and an elastic
link 315 are heated to contract and generate a surface tension due
to thermal contraction so as to lift up the movable part 21. The
first elastic joint 311, the elastic link 315 and the third elastic
joint 313 are mutually hampered by surface tension arising from the
thermal contraction process. As a result, a curved movable part 21
could be formulated.
[0044] Please refer to FIG. 6 and FIG. 7. The present invention
provides a third type of self-assembly micro blade to achieve a
micro blade structure having multi-layer and curve moving parts.
The self-assembly micro blade includes at least a first movable
part 22 and a second movable part 23 of a microstructure; and an
elastic joint 31 provided between the first movable part 22 and an
outer ring 11 of a micro motor and between the first movable part
22 and the second movable part 23 respectively. The elastic joint
31 and the elastic link 315 are composed of a photosensing
polyimide film. Surface tension is generated by each elastic joint
31 and the elastic link 315 through a reflow process to bend the
movable part of the microstructure in a multi-layer and curved
manner and lift it up.
[0045] The design that elastic joint and elastic link are provided
between each movable part 21 and the outer ring 11 of the micro
motor lies in that a first elastic joint 311 is defined on the
first movable part 22, a second elastic joint 312 is defined on one
side of the second movable part 23, an elastic link is defined
above the second elastic joint 312 of the second movable part 23,
and a fourth elastic joint 314 is defined on the elastic link 315
of the second movable part 23. Given the above-mentioned reflow
process, a multi-layer and curved micro blade could be
achieved.
[0046] To sum up, a comparison between the present invention and
lead tin alloy ball is made as a reference to advantageous and
disadvantageous characteristics thereof:
[0047] The present invention has no phenomenon of lead
pollution.
[0048] The present invention won't need to evaporate a layer of
gold pad additionally as a connection interface, and thus the
manufacturing process thereof is simpler and the cost thereof is
lower.
[0049] The present invention performs alignment with extremely high
accuracy by using photolithography. Therefore, the accuracy of the
micro blade of the present invention is better.
[0050] The present invention could be fully automatic in
operation.
[0051] The micro blade lifted up by the design of a plurality of
elastic joints and elastic links in the present invention has
multi-layer and curved movable parts.
[0052] The miniaturized size of the present invention is not
subject to any limitation.
[0053] Furthermore, a comparison between the present invention and
the one using photoresist as elastic joint is made as a reference
to advantageous and disadvantageous characteristics thereof:
[0054] Although photosensing polyimide film and photoresist are
both polymer, photosensing polyimide film could withstand organic
solution better since its surface tension is larger than that of
photoresist. Consequently, the present invention has no doubt that
elastic joint will be dissolved and destructed by Isopropyl alcohol
(IPA).
[0055] As photosensing polyimode film can resist organic solution,
a wet etch process having relatively lower cost could be applied,
and thus the cost of the present invention is relatively lower.
[0056] The present invention is a micro blade that could completely
solve many drawbacks resulting from the self assembly of a
conventional micro blade, could be adopted to the development
technique of a self-assembly micro fan and could break through the
technical barrier of a conventional micro fan by using the
foregoing description and design, so as to achieve the object of a
micro blade with curved and multi-layer movable part, increasing
flow rate and control, and improved flow length. From the
above-mentioned characteristics those features not only have a
novelty among similar products and a progressiveness but also have
an industry utility.
[0057] While the invention has been described in terms of what is
presently considered to be the most practical and preferred
embodiments, it is to be understood that the invention needs not be
limited to the disclosed embodiments. On the contrary, it is
intended to cover various modifications and similar arrangements
included within the spirit and scope of the appended claims, which
are to be accorded with the broadest interpretation so as to
encompass all such modifications and similar structures.
* * * * *