Liangyu Cui

A novel monolithic piezoelectric actuated flexure-mechanism based wire clamp for microelectronic device packaging

A novel monolithic piezoelectric actuated wire clamp is presented in this paper to achieve fast, accurate, and robust microelectronic device packaging. The wire clamp has compact, flexure-based mechanical structure and light weight. To obtain large and robust jaw displacements and ensure parallel jaw grasping, a two-stage amplification composed of a homothetic bridge type mechanism and a parallelogram leverage mechanism was designed. Pseudo-rigid-body model and Lagrange approaches were employed to conduct the kinematic, static, and dynamic modeling of the wire clamp and optimization design was carried out. The displacement amplification ratio, maximum allowable stress, and natural frequency were calculated. Finite element analysis (FEA) was conducted to evaluate the characteristics of the wire clamp and wire electro discharge machining technique was utilized to fabricate the monolithic structure. Experimental tests were carried out to investigate the performance and the experimental results match well with the theoretical calculation and FEA. The amplification ratio of the clamp is 20.96 and the working mode frequency is 895 Hz. Step response test shows that the wire clamp has fast response and high accuracy and the motion resolution is 0.2 μm. High speed precision grasping operations of gold and copper wires were realized using the wire clamper.

Laser-induced changes in titanium by femtosecond, picosecond and millisecond laser ablation

In order to realize the qualitative control of the laser-induced changes trend and the quantitative control of the laser-induced changes range in titanium upon laser irradiation with different pulse duration, comparative ablation experiments by femtosecond, picosecond and millisecond pulsed lasers were carried out on titanium in this study. Then the final surface morphology, aspect ratio, chemical composition and microstructural state of the ablated titanium were analyzed by laser scanning confocal microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy, respectively. The dependency of the morphology, size, composition and microstructure of ablated titanium on laser pulse duration variation were emphatically discussed. It is found that, as the laser pulse duration increases from femtosecond to millisecond scale, surface morphology quality of ablated titanium gets worse, aspect ratio of microgroove decreases, proportion of titanium oxides in final ablation products becomes larger and the microstructural state of ablated titanium has a higher amorphization degree, which can be attributed to the decreased laser intensity per pulse and enhanced heat conduction effect in titanium with the pulse duration increasing.

Development and Testing of a XYZ Scanner for Atomic Force Microscope

Atomic force microscopy (AFM) is a widely used tool in nano measurement and manipulation techniques. However, a traditional AFM system suffers from the limitation of slow scanning rate, due to the low dynamic performance of piezoelectric positioners. As an important part of AFM system, scanner will have a significant impact the result of the scanning imaging and operation. It is well know that high-speed operation of an AFM are increasingly required, and it is also a challenge for the researchers. In this paper, we proposed a parallel kinematic high-speed piezoelectric actuator (PZT) XYZ scanner. The design is aimed at achieving high resonance frequencies and low cross-coupling. The developed stage consists of a parallel kinematic XY stage and a Z stage. The Z stage is mounted on the central moving platform of the XY stage. To achieve the design objective, several parallel leaf flexure hinge mechanisms, arranging symmetrically around the central moving platform of the XY stage, are utilized to provide large stiffness and reduce cross-coupling. For the Z stage, a symmetrical leaf flexure parallelogram mechanism is adopted to achieve high resonance frequencies and decoupling. Then, finite element analysis (FEA) is utilized to validate the characteristics of the XYZ scanner. Finally, extensive experiments are conducted, demonstrating feasibility of the proposed scanner.

Design and stiffness analysis of a XYZ scanning stage

A compact XYZ precision scanning stage is designed in this paper, which is assembled by a XY and a Z precision positioning stages. Each stage is driven by piezoelectric actuator, and guided by symmetric parallel flexible hinges, respectively. These parallel flexible hinges are arranged symmetrically to reduce cross-coupling among X-, Y- and Z-axis. In addition, the theoretical stiffness modeling of the scanner was carried out. According to an effective strain energy method, the stiffness model are obtained, which provides a useful tool to calculate the stiffness of scanner. Furthermore, the characteristics of the XYZ scanner are evaluated in this paper by finite element analysis simulation. The simulation results show that the cross-axis coupling ratio of the proposed scanner is less than 0.91%, indicating excellent decoupling performances. Meanwhile, and the dynamic characteristics are investigated and the results are shown that the design scanner provides the large dynamic bandwidth.

Fabrication of polymer optical diffusers by buffer-assisted ultrasonic embossing

Ultrasonic embossing and welding process is a fast and low cost manufacturing method for polymer devices in ambient temperature. More and more polymer MEMS devices, like optical devices and bio-MEMS devices are emerging in academic and engineering areas, due to the advantages of polymer materials, like low cost and easy manufacturing. In this paper, a buffer-assisted ultrasonic embossing process, using a layer of polymer film as buffer layer, was utilized to fabricate a flexible polymer optical diffuser, of which the height of the embossed microstructure is larger than the thickness of the polymer film. The optical experiment is conducted and the results verified the feasibility of the proposed buffer-assisted ultrasonic embossing process, so this buffer-assisted ultrasonic embossing process can be more polymer devices with large characteristic dimension form thin polymer films.

Development and Application of Molded Interconnect Devices

With the improvements of electromechanical systems’ automation and intelligence, contradiction between the high integration, high performance and miniaturization, low cost has become the principal reason restricting the development of electromechanical system. The emergence of molded interconnection device (MID) technology provides a new way to resolve this contradiction. Integration of the mechanical and electrical functions in electromechanical system onto the same polymer molded base structure, replacement of the tradition printed circuit board (PCB), design and processing of 3D circuit system on polymer molded base structure surface distinguishes MID technology from others. MID technology can not only save space occupied by the electromechanical system and improve the system integration, but also can simplify the assembly process and lower the cost. In this study, present research and future development of MID technology were introduced first. Then the main technical problems involved in MID processing including the design method of MID, materials technology, equipment technology, surface mounted devices (SMD) assembly technique, and so on were analyzed systematically. Finally, using the ultrasonic micro embossing technology, a manufacturing method of polymer circuit board, radio frequency identification (RFID) antenna, microelectrode arrays, and some other polymer foil MID was proposed. Based on the in-depth analysis of polymer foil MID’s characteristics, polymer foil MID are expected to have a broad application in the field of microfluidic chip. Development and Application of Molded Interconnect Devices

Ultrasonic assisted imprint for microfluidic chips

Microfluidic chips are new MEME devices built on several square millimeter substrate to handle microliter or nanoliter fluid, wildly used in the fields of life science and bio-chemical detection, with the advantages of low reagents consuming, high efficiency and low cost. In the highly integrated microfluidic chips, flow sensors are essential parts; however, most traditional flow sensors are not suitable to be integrated into microfluidic chips, because of their complex fabrication process and high cost. In this paper, a new thermal sensitive element on polymer foil is fabricated by ultrasonic assistant imprint technology and integrated into microfluidic chip to be an anemometer flow sensor. Then the anemometer flow sensor is experimentally studied under power constant condition and the experiment shows application potential in the microfluidic chips.

Development of the Thermal Error Measurement System for Machine Tool Spindle Based on Virtual Instruments Technology

Based on the virtual instruments technology, a data acquisition and pretreatment system for monitoring the thermal signals of the spindle of machine tool is suggested, and the temperature rise and thermal distortion signals are collected synchronously. The software of the system introduces Producer/Consumer pattern to improve data sharing and buffered communication between data collecting and data storage processes, by this means, data missing and iteration are avoided, although these two processes run at different rates. At mean time, Matlab Script interface technique is utilized to realize the hybrid programming of Matlab and LabVIEW, which makes the acquisition system possess the ability of accomplishing complex algorithm.