1. MEMS PACKAGING & ASSEMBLY ISSUES
SMTAi 2000
Chicago
Ken Gilleo, PhD
ET-Trends
Intellisense
© ET-Trends LLC

2. OUTLINE MEMS Introduction & Survey Packaging challenges
Assembly issues
MOEMS; let there be light* (optics)
Conclusions
* control
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3. Nano World Where all technology converges Optics Electronics Mechanics
The convergence point of electronics, mechanics, physics, chemistry and biology, etc.
Electronics
Mechanics
MEMS
MOEMS OE OM
Optics
Where all technology converges
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4. Micro-Electro-Mechanical System
MEMS
Micro-Electro-Mechanical System
Semiconductor processing used
Merges mechanical motion & electronics
VERSATILE
sensing
computing
motion
control
U of W
Marauder MEMS Monster?
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5. MEMS Processing Electronics fab: standard methods Silicon Machining:
Define mechanical parts by lithography
Form sacrificial SiO2 in “removal” areas
Etch away SiO2 to free mechanical parts
Many other micro-machining processes are available
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6. MEMS Motion Deformable; cantilevers, beams, membranes Sliding, linear
Rotating; partial, full, multi-plane
Rotating Inter-contact; gears, wheels
Hinges
Combinations
Sandia, UW, AD
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7. MEMS “Engines” Electrostatic; very efficient* Thermal Electromagnetic
Pneumatic
Hydraulic
Photoelectric
*Surface area is relatively high, mass is very low; surface effects are important
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8. MEMS Products
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9. MEMS Structures IBM MEMS DNA Detector © ET-Trends LLC
Electrostatic Relay - UW

10. More MEMS Are the Microbots” coming? Guess? © ET-Trends LLC Tweezers
UW-Madison

11. The real problem may be Lack of KNOWLEDGE,
Packaging
The real problem may be Lack of KNOWLEDGE,
not
Lack of TECHNOLOGY
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12. Packaging Challenges
MEMS devices can be very fragile
pre-package handling concerns
more protection by package
Most require hermetic package ($$$)
MOEMS (later) requires a window & controlled atmosphere.
Biggest challenge: cost-effective, high volume packaging
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13. MEMS Packaging Types Traditional hermetic; metal or ceramic
Cap-on-Chip
wafer-level
device-level
Silicon Sandwich
Near- and non-hermetic
Selective/partial packaging
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14. Packaging No Standards DPL Modules, TI (HERMETIC) (HERMETIC)
Accelerometer (CAP)
Ink Jet MEMS in TAB Package (SELECTIVE)
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(HERMETIC)
MicroRelay - Cronos (HERMETIC)
(HERMETIC)

15. Selective Encapsulation
MEMS
Ink Jet “Gun”
I-TAB package
This type of machine can be used to selectively encapsulate MEMS- one like this is used on ink jet cartridges.
Courtesy of Speedline
MEMS bare die
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16. Cap-on-Carrier Silicon or Metal Cap Molded or Liquid Encapsulant
MEMS IC
Solder, weld, or polymer
This packaging method is suitable for accelerometers, gyroscopes and other motion detectors that can be sealed.
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17. Cap-on-Chip (level-0) CAP Vacuum MEMS Chip
Seal
Vacuum
MEMS Chip
Can now be handled like an ordinary die - almost!
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18. Cap-on-Chip Variants Etched Silicon, ceramic, glass
Indent Reflow Sealing (IMEC)
Wafer-Level Protected (AMKOR)
Silicon Sandwich; GIT
Metal, low CTE?
Plastic?
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19. Cap-on-Chip Overmolding
1. Apply cap to device or wafer;
solder, weld, bond.
MEMS IC
May require gel coat
to protect thin cap
2. Attach & bond device
3. Conventional overmolding followed by solder ball attach.
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20. MOEMS Projection Mirrors Photonics Switches Gratings Fiber Aligners
Micro-opto-electro-mechanical systems
Projection Mirrors
Photonics Switches
Gratings
Fiber Aligners
Modulators, Shutters
Movable Lenses
A Market powered by the Internet!
A Technology that will power the Internet!
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21. Cronos (JDS-Uniphase)
Optical MEMS or
MOEMS
Fiber Alignor
Cronos (JDS-Uniphase)
Micro-Mirror
Lenses Array
Rotating Mirror-UCLA
Pop-Up Lens
Micro-Mirror Array - TI
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Shutter - Sandia
Cross-switch mirror

22. Micro-Mirror Close-up by TIon
off
World’s most complex machine?
Ref. “Digital Light Processing TM for High-Brightness, High-Resolution Applications”
Larry J. Hornbeck,
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23. MOEMS Micro-Mirror WINDOW HEAT SINK HERMETIC Getter Weld or seal
Ceramic
HEAT SINK
HERMETIC
250,000 mirrors
MEMS Digital Mirrors
one section
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24. Flip Chip for MOEMS? Light Pipe Encapsulant MEMS FLIP CHIP Underfill
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25. MOEMS Flip Chip BGA Package
Seal or dam
MEMS IC
Light Pipe
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26. GETTERS
Agents that counteract harmful contaminants within a sealed package; this includes solids, liquids, gases and combinations.
Will guard and control package environment over an extended time.
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27. Types of Getters Particle: attracts and holds. Moisture: desiccant.
Gas: adsorbs/chemically converts to liquid or solid.
Combinations.
Others are possible.
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28. Why Use Getters? Remove harmful agents from the device environment.
Control atmosphere for many years.
Provide the maximum security and reliability; highest life expectance.
Protect optics; mirrors, lenses
Reduce wear
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29. Available Getters Moisture Particle Hydrogen Combinations
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30. Assembly Issues Safe handling; some are shock sensitive
Orientation; can be critical
PWB & joint; change affects MEMS sensitivity
Testing; not well established for some devices
Free path; light, sound, molecules
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31. Accelerometer Example
For air bags
INOPERABLE
Analog Devices Chip
Sensing Mechanism (AD)
High surface area = high attraction =
“STICTION”
Result of rough
handling = “dead” component
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32. Stiction Solutions Liquid lubricants Gases, vapors
Polymer films; Fluorinated Parylene
Treatments
Design; “no contact”
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33. Assembly Factors Component skew Component non-coplanarity
All change accelerometer behavior
Component skew
Component non-coplanarity
Solder joint mass and shape
Flux residue
Board thickness
Board warpage
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34. Conclusions MEMS: a key 21st century technology
The packaging is more difficult
Expect new & unusual packages
Assembly has new constraints
New guidelines are needed
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Let’s take the bite out of MEMS