© et-trends llc 1 mems packaging & assembly issues ken gilleo, phd et-trends [email protected]...
TRANSCRIPT
© ET-Trends LLC 1
MEMS PACKAGING & ASSEMBLY ISSUES
Ken Gilleo, PhD
ET-Trends
SMTAi 2000
Chicago
SMTAi 2000
Chicago
Intellisense
© ET-Trends LLC 2
OUTLINE
• MEMS Introduction & Survey
• Packaging challenges
• Assembly issues
• MOEMS; let there be light* (optics)
• Conclusions
* control
© ET-Trends LLC 3
Nano World
Where all technology converges
The convergence point of electronics, mechanics, physics, chemistry and biology, etc.
ElectronicsM
echan
ics
Optics
MEMS
OE OM
MOEMS
© ET-Trends LLC 4
MEMS
• Semiconductor processing used
• Merges mechanical motion & electronics
• VERSATILE
– sensing
– computing
– motion
– control
Marauder MEMS Monster?Marauder MEMS Monster?
Micro-Electro-Mechanical System
U of W
© ET-Trends LLC 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
© ET-Trends LLC 6
MEMS Motion• Deformable; cantilevers, beams, membranes
• Sliding, linear
• Rotating; partial, full, multi-plane
• Rotating Inter-contact; gears, wheels
• Hinges
• Combinations
Sandia, UW, AD
© ET-Trends LLC 7
MEMS “Engines”
• Electrostatic; very efficient*
• Thermal
• Electromagnetic
• Pneumatic
• Hydraulic
• Photoelectric *Surface area is relatively high, mass is very low; surface effects are important
*Surface area is relatively high, mass is very low; surface effects are important
© ET-Trends LLC 8
MEMS Device Input Output
Accelerometer Motion Electrical3D Motion Detection Motion ElectricalInk Jet Electrical Motion, fluidDigital Mirror Array Electrical and light Controlled lightMicro-Spectrophotometer “Light” ElectricalDNA Analyzer Biological samples ElectricalDisk Drive Heads Magnetic ElectricalOptical Switches Electrical and light Electrical & lightCapacitors, Tunable Electrical/RF RFRF Tuners Electrical/RF RFGyroscopes Electrical/motion ElectricalDiagnostics (in vitro) Electrical/liquid ElectricalInfrared Imagers IR/electrical ElectricalMicro-Relay Electrical Electrical
Pressure Sensors Force directly/indirectly Electrical
MEMS Products
© ET-Trends LLC 9
MEMS Structures
IBM MEMS DNA Detector
Electrostatic Relay - UW
© ET-Trends LLC 10
More MEMS
TweezersUW-Madison
Are the Microbots” coming?
Are the Microbots” coming?
Guess?Guess?
© ET-Trends LLC 11
The real problem may be Lack of
KNOWLEDGE,not
Lack of TECHNOLOGY
The real problem may be Lack of
KNOWLEDGE,not
Lack of TECHNOLOGY
© ET-Trends LLC 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
© ET-Trends LLC 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
© ET-Trends LLC 14
Packaging
MicroRelay - Cronos (HERMETIC)
Accelerometer (CAP)
Ink Jet MEMS in TAB Package (SELECTIVE)
DPL Modules, TI (HERMETIC)
No StandardsNo Standards
(HERMETIC)
(HERMETIC) (HERMETIC)
© ET-Trends LLC 15
This type of machine can be used to selectively encapsulate MEMS- one like this is used on ink jet cartridges. Courtesy of Speedline
Selective Encapsulation
Ink Jet “Gun”
I-TAB package
Ink Jet “Gun”
I-TAB package
MEMS bare die
MEMS
© ET-Trends LLC 16
Cap-on-Carrier
MEMS IC
This packaging method is suitable for accelerometers, gyroscopes and other motion detectors that can be sealed.
This packaging method is suitable for accelerometers, gyroscopes and other motion detectors that can be sealed.
Silicon or Metal CapMolded or Liquid Encapsulant
Solder, weld, or polymer
© ET-Trends LLC 17
Cap-on-Chip(level-0)
MEMS Chip
CAP
Vacuum
Seal
Can now be handled like an ordinary die - almost!
Can now be handled like an ordinary die - almost!
© ET-Trends LLC 18
Cap-on-Chip Variants• Etched Silicon, ceramic, glass
– Indent Reflow Sealing (IMEC)
– Wafer-Level Protected (AMKOR)
• Silicon Sandwich; GIT
• Metal, low CTE?
• Plastic?
© ET-Trends LLC 19
Cap-on-Chip Overmolding
MEMS IC
2. Attach & bond device
May require gel coatto protect thin cap
1. Apply cap to device or wafer;solder, weld, bond.
3. Conventional overmolding followed by solder ball attach.
© ET-Trends LLC 20
MOEMS
• Projection Mirrors
• Photonics Switches
• Gratings
• Fiber Aligners
• Modulators, Shutters
• Movable Lenses
Micro-opto-electro-mechanical systems
A Market powered
by the Internet!
A Market powered
by the Internet!
A Technology that will
power the Internet!
A Technology that will
power the Internet!
© ET-Trends LLC 21
Optical MEMS or
Cronos (JDS-Uniphase)Micro-Mirror
Lenses Array
Micro-Mirror Array - TI
Pop-Up Lens
Rotating Mirror-UCLA
Cross-switch mirrorShutter - Sandia
Fiber Alignor
© ET-Trends LLC 22
Micro-Mirror Close-up by TIon off
Ref. “Digital Light Processing TM for High-Brightness, High-Resolution Applications”Larry J. Hornbeck, [email protected]
World’s most complex machine?
World’s most complex machine?
© ET-Trends LLC 23
MOEMS Micro-Mirror
WINDOW
HEAT SINK
Ceramic
Weldor
seal
MEMS Digital Mirrorsone section
HERMETIC
Getter
250,000 mirrors
© ET-Trends LLC 24
Encapsulant
Flip Chip for MOEMS?
MEMS FLIP CHIP
Light PipeUnderfill
© ET-Trends LLC 25
MOEMS Flip Chip BGA Package
MEMS IC
Seal or dam
Light Pipe
© ET-Trends LLC 26
Agents that counteract harmful contaminants within a sealed package; this includes solids, liquids, gases and combinations.
GETTERS
Will guard and control package environment over an extended time.
Will guard and control package environment over an extended time.
© ET-Trends LLC 27
• Particle: attracts and holds.
• Moisture: desiccant.
• Gas: adsorbs/chemically converts to liquid
or solid.
• Combinations.
• Others are possible.
Types of Getters
© ET-Trends LLC 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
© ET-Trends LLC 29
• Moisture
• Particle
• Hydrogen
• Hydrogen
• Combinations
Available Getters
© ET-Trends LLC 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
© ET-Trends LLC 31
Accelerometer Example
Analog Devices ChipSensing Mechanism (AD)
Result of rough
handling = “dead” component
Result of rough
handling = “dead” component
High surface area = high attraction =
“STICTION”
High surface area = high attraction =
“STICTION”
For air bags
INOPERABLE
INOPERABLE
© ET-Trends LLC 32
Stiction Solutions
• Liquid lubricants
• Gases, vapors
• Polymer films; Fluorinated Parylene
• Treatments
• Design; “no contact”
© ET-Trends LLC 33
Assembly Factors
• Component skew
• Component non-coplanarity
• Solder joint mass and shape
• Flux residue
• Board thickness
• Board warpage
All change accelerometer behavior
© ET-Trends LLC 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
Let’s take the bite out of MEMS