MECH 466. Micro Electromechanical Systems. Laboratory Manual Laboratory #4: Microassembly of MEMS

Transcription

1 MECH 466 Micro Electromechanical Systems Laboratory Manual Laboratory #4: Microassembly of MEMS Department of Mechanical Engineering, University of Victoria N. Dechev, 2009, University of Victoria Page 1 of 10

2 Report: The laboratory report must be in the following format: (i) (ii) (iii) (iv) (v) Title Page i. Include your name, student number, date of lab, etc Objective Data i. Include data and images you collected. ii. Comment on any Sources of Error that may have influenced the data, or the collection of the data. Discussion i. Compare and contrast the experimental results in comparison to the theoretical/analytical results. ii. Include answers to the questions that pertain to the experiments, as listed in the Lab Write-up section. Conclusion Please organize the laboratory report into the five divisions indicated above (Title Page, Objective, Data/Images, Discussion (with questions answered), and Conclusion). The report should be a maximum of 5 pages (double spaced text), including figures, and data. Appendices may be added as extra pages. N. Dechev, 2009, University of Victoria Page 2 of 10

3 Laboratory #4: Microassembly of MEMS Devices Purpose: The purpose of this laboratory is to try out a technique called microassembly, to assemble MEMS microstructures. A second purpose is to familiarize the student with a motorized micromanipulator for probing and interacting with MEMS devices. Introduction: Microassembly is a post-processing technique that can be used to construct MEMS devices that cannot be directly fabricated using conventional micromachining methods. The microassembly system used in this laboratory consists of five major subsystems, which are: (1) the micromanipulator, (2) the endeffector with an attached microgripper, (3) the grasp interface system, (4) the micro-parts and basemicro-parts, and (5) the micro-joint system. The student will make use these five sub-systems, through the completion of a microassembly task. Laboratory Preparation: Review the Lecture 18 notes to familiarize yourself with the high-level microassembly concept. Review the diagram of the micromanipulators shown in Appendix A, to familiarize yourself with the machine components. Review the diagram in Appendix B of the microgripper, to familiarize yourself with the microgripper operation. Review Appendix C to familiarize yourself with the micro-part Interface Feature. Review Appendix D to familiarize yourself with the micro-part, the micro-part joint feature (Key-Lock), and the substrate joint feature. Procedure: Setup: (1) The lab technician/ta will mount a MEMS chip onto the worktable of the micromanipulator. (2) The lab technician/ta will bond a microgripper to the pin-probe of the micromanipulator. (Observation #1): Bonding of a MEMS microgripper: (1) Mount the probe pin holder (with a tungsten probe installed) on the Beta Axis of the micromanipulator (2) Locate the tip of the probe pin using the Manual XYZ Stage, i.e. bring it into the field of view of the camera. (3) Locate the desired microgripper for a given task on the MEMS chip. (4) Localize the probe pin tip with respect to the microgripper pad, by touching down on the microgripper pad with the tip. Be careful not to crush the microgripper with too much pressure. (5) Zero the coordinate system in software (6) Raise the probe pin by 10 mm (10,000 microns) and apply UV adhesive to the tip. (7) Return the probe pin to the zero position (8) Watch/Verify that the adhesive flows from the probe pin onto the microgripper pad. (9) Put on your UV-Glasses. If you are unable to use UV-Glasses, you will be required to exit the laboratory until the UV-bonding step is completed. (10) The lab technician/ta will expose the adhesive with the UV spot light system. (11) After UV adhesive has cured, command the micromanipulator to move the probe pin upwards along the z-axis. This will raise the microgripper away from the substrate, thereby N. Dechev, 2009, University of Victoria Page 3 of 10

4 breaking off the tethers that hold it down. (12) Rotate the microgripper 3 CCW about the Beta Axis to ensure the gripper tips are slightly lower than the bonding pad. (13) Record the Beta Axis orientation as the grasping angle. Experiment #2: Grasping Micro-parts (1) Locate the micro-part of interest. (Micro-part shown in Appendix D) (2) Line up the microgripper with the interface feature located on the micro-part. (3) Insert the microgripper tip into the interface feature. (movement in +x direction) (4) After insertion, continue to move in the +x direction, to cause the tethers to break. (5) After both tethers have broken, raise the microgripper (+z direction) away from the substrate. (6) The microgripper should now be holding the micro-part, and is ready to join the micro-part. (7) Record the current grasp angle of the Beta Axis Experiment #3: Joining Micro-parts (1) Locate the base structure to which the grasped micro-part will be joined. This will require you to focus down beyond the microgripper, using the Manual XYZ Stage that holds the camera. (2) After locating the part, record the location of the x, y, z Coordinate System. (3) Using the Manual XYZ Stage, focus back up to the microgripper. (4) Raise the microgripper (which holds the micro-part), above the substrate by at least microns. (5) Rotate the Beta Axis by 90 CCW to re-orient the microgripper. (6) (Optional:) Rotate the Alpha Axis if necessary, to re-orient the base structure. (7) Record the new angle of the Beta Axis and Alpha Axis (8) Locate the tip of the micro-part (held in the microgripper) using the Manual XYZ Stage, i.e. bring the joint feature of the micropart into the field of view of the camera. (9) Return to the base structure location (10) Line up the micro-part joint feature with the base structure joint feature. (11) Insert the micro-part joint feature into the base structure joint feature. (12) Retract the microgripper away from the joint feature. If the joint is secure, the microgripper will automatically release the micro-part. (13) Inspect the joint and take pictures. (14) Raise the microgripper microns above the substrate. (15) Rotate the Beta Axis back by 90 CW return to the original grasping angle (16) Repeat the assembly procedure at least once more, i.e. steps (1 7 of Exp#2, followed by 1 15 of Exp#3). N. Dechev, 2009, University of Victoria Page 4 of 10

5 Laboratory Write-up: In relation to Observation #1, answer the following questions in the Discussion Section of your laboratory report: (Q1) Comment on the UV-Bonding technique. Can you suggest any other methods to bond the microgripper to the probe-pin. In relation to Experiment #2, answer the following questions in the Discussion Section of your laboratory report: (Q1) How did the grasping task compare to that described in the lecture notes? (Q2) Comment on the visual system, i.e. field of view and focus during the grasping task. Was it sufficient? Any drawbacks or any advantages? Any suggestions for improvement? (Q3) Comment on any unexpected results (if you observed any). What may have caused these? In relation to Experiment #3, answer the following questions in the Discussion Section of your laboratory report: (Q4) How did the joining task compare to that described in the lecture notes? (Q5) Comment on the visual system, i.e. field of view and focus during the joining task. Was it sufficient? Any drawbacks or any advantages? Any suggestions for improvement? (Q6) Comment on any unexpected results (if you observed any). What may have caused these? N. Dechev, 2009, University of Victoria Page 5 of 10

6 Appendix A: Micromanipulator Diagram: N. Dechev, 2009, University of Victoria Page 6 of 10

7 N. Dechev, 2009, University of Victoria Page 7 of 10

8 Appendix B: Microgripper Design Diagram: Figure B-2: SEM of Microgripper Tips Figure B-1: Microgripper Operation Figure B-3: Cross-Section illustration of Microgripper Tips N. Dechev, 2009, University of Victoria Page 8 of 10

9 MECH 466 Microelectromechanical Systems Appendix C: Micro-part Interface Feature (Used to grasp micro-part with microgripper): Figure C-1: SEM of Micro-Part Interface Feature that is grasped by microgripper tips. Figure C-2: Cross-Section illustration of micro-part Interface Feature. Appendix D: Micro-part with Key-Lock Figure D-1: Test-Micro-Part with Key-Lock Tip. (a) Joined into a T Slot, and a Round Slot. N. Dechev, 2009, University of Victoria Page 9 of 10

10 Figure D-2: Detailed Illustration of Key-Lock Geometry N. Dechev, 2009, University of Victoria Page 10 of 10