Power plants – Motor operated by expansion and/or contraction of a unit of... – Mass is a solid
Reexamination Certificate
2002-06-28
2004-04-13
Nguyen, Hoang (Department: 3748)
Power plants
Motor operated by expansion and/or contraction of a unit of...
Mass is a solid
C060S528000
Reexamination Certificate
active
06718764
ABSTRACT:
TECHNICAL FIELD
This invention is related to positioning devices in microelectromechanical systems (MEMS) and, more particularly, to using a bimorph actuator that has been modified to affect the power off position of the positioning device.
BACKGROUND OF THE INVENTION
MicroElectroMechanical (“MEM”) devices comprise integrated micromechanical and microelectronic devices. The term “microcomponent” will be used herein generically to encompass microelectronic components, micromechanical components, as well as MEMs components. The advances in microcomponent technology have resulted in an increasing number of microcomponent applications. Accordingly, a need often arises for precise positioning of microcomponent devices. For example, it is often desirable to position a microcomponent in alignment with a target position. For instance, for certain applications it may be desirable to align a microcomponent with another device. Because of the small size of microcomponents, they often require very precise positioning (e.g., precise alignment with another device). For example, in some cases a misalignment of only a few microns may be unacceptable. In fact, in some cases the size of the microcomponent being aligned may be only a few microns. Also, microcomponents present particular difficulty in handling and positioning operations.
Plastic deformation of single composition MEM devices is known. For example, U.S. Pat. No. 6,261,494, entitled METHOD OF FORMING PLASTICALLY DEFORMABLE MICROSTRUCTURES, the disclosure of which is incorporated herein by reference herein, teaches a method of plastically deforming MEM structures. Copending U.S. patent application Ser. No. 09/932,489, filed Aug. 17, 2001, and entitled SYSTEM AND METHOD FOR PRECISE POSITIONING OF MICROCOMPONENTS, the disclosure of which is hereby incorporated by reference herein, teaches deforming microactuators to fix the position of microcomponents.
Stress relaxation in bimorph microstructures is also known. For example, in the article entitled “Stress Relaxation of Gold/Polysilicon Layered MEMS Microstructures Subjected to Thermal Loading,” by Zhang and Dunn, stress relaxation is studied for gold within a gold/polysilicon bimorph device. Creep may occur at elevated temperatures and may cause deformation if the bimorph is exposed to an elevated temperature over a period of time. Accordingly, yielding mechanisms in some materials are time and temperature dependent as well as stress dependent.
Microcomponents are commonly implemented in the field of optoelectronics. Generally, when coupling optoelectronic components, alignment is very important. That is, alignment of optoelectronic components is often critical for proper operation of an optoelectronic device. A relatively slight misalignment of optical components may drastically alter an optical device's performance. For example, accurate alignment of components is often important for ensuring proper propagation of an optical signal to/from/within an optoelectronic device. For instance, optoelectronic modules, such as optoelectronic receivers and optoelectronic transmitters commonly require proper alignment of microcomponents therein for proper operation. In general, proper alignment is desired to minimize the amount of attenuation within such optoelectronic devices.
One microcomponent that often requires proper alignment is an optical fiber. For example, in an optoelectronic receiver, a fiber is aligned with an optical detector, typically a PIN photodiode. Very large fibers may have light-guiding cores with a diameter of approximately 1 millimeter (mm) or 1000 microns (&mgr;m), but such fibers are rarely used in communications. Standard glass communication fibers have cladding diameter of 125 &mgr;m and light-guiding cores with diameter of approximately 8 to 62.6 &mgr;m. Proper alignment of the end of the optical fiber (which may be referred to as the “fiber pigtail”) with the optical detector is important to ensure that a light signal is properly received by the optical detector. Similarly, in an optoelectronic transmitter, an optical fiber is aligned with a light source, such as a light-emitting diode (LED) or laser diode. Proper alignment of the end of the optical fiber with the light source is important to ensure that a light signal is properly communicated from the light source to the optical fiber.
The difficulty in achieving proper alignment of optical fiber is often increased because of variances in the size of fiber core diameters. For example, typical commercial graded-index fiber commonly specify a 50 &mgr;m nominal fiber core diameter that may vary within a tolerance of ±3 &mgr;m. Also, alignment/positioning of the light-guiding core within the sleeve of a fiber optic cable often varies (i.e., the core is not always centered within the sleeve), thereby further increasing the difficulty of properly designing a fiber with another optoelectronic device.
Various techniques have been developed for handling and positioning microcomponents, such as optical fibers. According to one technique, a high-precision, external robot is utilized to align microcomponents within devices. However, such external robots are generally very expensive. Additionally, external robots typically perform microcomponent alignment in a serial manner, thereby increasing the amount of time required for manufacturing microcomponent devices. That is, such robots typically perform alignment for one component at a time, thereby requiring a serial process for assembling microcomponents utilizing such a robot.
According to another technique, microactuators, such as electrothermal actuators, may be utilized to align microcomponents, such as optical fibers. For example, microactuators may be integrated within a device to align microcomponents within the device. Accordingly, use of such microactuators may avoid the cost of the above-described external robot. Also, if implemented within a device, the microactuators may enable parallel alignment of microcomponents. That is, multiple devices may have alignment operations performed by their respective microactuators in parallel, which may reduce the amount of time required in manufacturing the devices. Examples of techniques using microactuators integrated within a device to perform alignment of an optical fiber are disclosed in U.S. Pat. Nos. 6,164,837 and 5,602,955, the disclosures of which are hereby incorporated by reference herein.
Once a desired position is obtained for a microcomponent (e.g., alignment with another device) using either of the above techniques, such microcomponent may have its position fixed in some manner such that it maintains the desired position. Various techniques have been developed for fixing the position of microcomponents. According to one technique, an epoxy may be used to fix the position of a microcomponent. In another technique a low melting point bonding material, such as solder, may be used to fix the position of a microcomponent. Exemplary techniques that use solder to fix the position of an optical fiber are disclosed in U.S. Pat. No. 6,164,837, U.S. Pat. No. 5,692,086, and U.S. Pat. No. 5,745,624, the disclosures of which are hereby incorporated by reference herein.
According to another technique, an “active” alignment device may be utilized to fix the position of a microcomponent. Such an alignment device is “active” in the sense that electrical power has to be maintained in order to fix the alignment of a microcomponent. For example, in certain implementations that use microactuators integrated within a device to perform alignment of microcomponents, power to such microactuators must be maintained in order to maintain (or fix) the position of the microcomponents being aligned.
Plastic deformation micro-assembly has been demonstrated using Plastic Deformation Magnetic Assembly (PDMA), such as in the article entitled “Plastic Deformation Magnetic Assembly (PDMA) of 3D Microstructures: Technology Development and Application,” by J. Zou, J. Chen and C Liu. However, PDMA technology can only be deformed to one position
Geisberger Aaron
Sarkar Niladri
Haynes and Boone LLP
Nguyen Hoang
Zyvex Corporation
LandOfFree
System and method for microstructure positioning using metal... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System and method for microstructure positioning using metal..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System and method for microstructure positioning using metal... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3204826