MEMS

1
MEMS its applications

• MEMS
• Microelectromechanical systems
• Applications
• Accelerometer
• Torque sensor
• Gyroscope  sensor
• Micromirror
• Micro components such as watch

2
Major processes of microfabrication

• Bulk micromachining
• Surface micromaching
• Dopant diffusion
• Deposit
• Masking
• Etching (dry or wet)
• LIGA
• X-ray lithography
• Electrodeposition
• molding

3
Electrical properties of material

• Electrical properties
• Conductivity, Resistivity, capacility and etc.
• How to measure
• Use voltmeter.
• Effect of temperature
• Higher temp, higher resistance. (
  )

4
Hardness test

• Principle
• Use hard testing device such as ball or cone
  shape, press on testing material.
• Major differences between HB and HRA testing
  standard
• Different shapes of indenters HB use
• ball shape HRA use diamond cone
• HB measure the diameter of the
• indentation HRA measure the depth.
• Effect of temperature on hardness
• Figure 22.1 textbook

5
Metal cutting

• Working principle
• Cutting processes remove material from the
  surface of the workpiece by producing chips.
• major types of machine tools
• Lathe
• Milling machine
• Drill press
• Machining center

6
Calculation of forging force(refer to Page 28,
Ch7 PPT)

• F Y A v
• Y Ken
• True strain e
• p l0(0.1/2)2 p lf (0.15/2)2 ?
  lf 0.1(0.1)2/(0.15)2 0.044m
• e ln(l0 / lf) ln(0.1/0.044) 0.82
• The parameter K and n
• For 85-15 brass K580MPa, n0.34 (Table 2.3
  in the textbook)
• A pr2 p(0.150/2)2 (m2)
• v 1.3

F (580106)(0.82)0.34(p)(0.15/2)2(1.3)1.24107N
12.4MN
7
Cutting by turning(refer to example 23.1 and
TABLE 23.3 _at_ page 685 of the textbook)

• Cutting time
• Cutting speed
• MRR

8
Cutting by turning (continue)

• Cutting force
• Since
• So
• or (yields the
  same answer)