© et-trends llc 1 ken gilleo – et-trends – [email protected] nathan kerrick, cookson...
TRANSCRIPT
© ET-Trends LLC
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Ken Gilleo – ET-Trends – [email protected]
Nathan Kerrick, Cookson Electronics
IBM MicroDrive: 351 MB
MEMS & GMR
Technology
IMAPS 200 Denver
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OUTLINE
• Hard Disk Drive overview
• GR and GMR technology
• Processing of hi-density heads
• The role of temporary adhesives
• HDD assembly
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The HDD (Hard Drive Disk)
Magnetic Disk
SliderFlex
Courtesy of 3M Co
Mag. Head Assembly
Mag. Head Assembly
Positioner
Assembly
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The HDD Head is key to Ultra-High Density
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HDD Technology
• Density increases surpass Moore’s Law.
• MR and GMR are true breakthroughs.
• Density records:– 30 million bits/in2 December 1999 (commercial)– 56 Gbits/in2 on April 2000 (lab)
• Density limits have not been reached.
• The technology is in the complex head.
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MR Head Technology
Contact
MR Sensing Layer(changes resistivity)Insulator Spacer
Soft Adjacent Layer
ShieldShield
bias
MR Effect: changes in electrical resistance by certain magnetically-soft when a magnetic field is turned on and off.
Magneto-Resistive
Measure as
“read” signal
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GMR Head Technology
Shield
Contact
Sensing Layer
Conducting Layer
Exchange Layer
Pinned Layer(magnetically oriented)
Shield
GMR is a quantum effect and relies on electron spin states; >2X more sensitive than GR
Giant Magneto-Resistive
bias
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Write Head
COIL
Write Current
SLIDER
Coil
WRITE HEAD
Magnetic medium
Writing Current
Magnetic coil creates field that“writes” by orienting disk domain medium
ONON
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Merged Read/Write Head
N SS NN SS NN SS N
WRITE
READ
Shield 1
RotatingDisk
Shield 2
Inductive Writing Element
MR or GMR
Sensor
READ WRITE
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Building MR/GMR Head Elements
• Semiconductor wafer fab
• Wafer thinning
• Wafer sawing
• Element planing/polishing
• Head assembly
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First, some adhesive basics.
MixingCasting Adhesive film
Wafer-applied adhesive for die attach
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Long-chained typically organic macromolecules made up of small repeating segments of monomers. Properties such as strength, flexibility, melting point and electrical characteristics can be ENGINEERED into the polymer.
- Engineered molecules
- Highly compatible-Tailored properties
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A polymer that is cross-linked so that melting does not occur under heating.
SOLID SOLID
A polymer that is capable of softening to a flowable "liquid" when heated and hardened again when cooled.
SOLID LIQUID (flowable)
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Polymer Types
Thermoplastic (Linear); mp, reworkable
Thermoset (3-D); infusible, memory
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Thermoplastic as a temporary adhesive
Independent chain motion allows melting; debonding.
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Thermoplastics
can be dissolved or debonded without
dissolving; swelling
Thermoplastics
can be dissolved or debonded without
dissolving; swelling
Solvent Molecules
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Thermoplastic Adhesive FORMS
• Film– sheets– rolls
• Preform– any shape from disk to complex
• Paste– for needle dispense– spin coat for wafer-level
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Resin & Filler Choices
• Fillers– Silver - Electrical & thermal conductivity– AlN, BeO - Thermal, but good dielectric– Unfilled - Insulating
• Resin bond ranges (thermoplastics):
– Low : 100oC– High :400oC– Typical: 150 - 250oC
For Most HDD Processes
Sometimes used to control static.
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Thermoset Adhesives
-------------Thermoplastic -------------
Dispense Oven Cure
DRY Heat & PressurePlace Part
Place Preform
Place
No Pressure Needed
Dispenseor Print
Place Part Dry/Fuse
No Pressure Needed
Coat Wafer:spin, print
Place Part Heat & Pressure
Pasteto
Substrate
Pasteto
Substrate
Pasteto
Wafer
Pasteto
Wafer
FILMFILM
Pasteto
Substrate
Not TemporaryNot Temporary
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Application Processes
• Liquid (paste)– Coat on wafer; spin, stencil, print; dry– Needle dispense on substrate or holder
• Film– Laminate to wafer, then run processes
• Preform (cut to wafer of row shape)– Bond to wafer– Bond to substrate
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Bonding Thermoplastics
GlassyState
Process Window
DecompositionDecomposition
TmaxTminTgTemperature
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Thermoplastic Properties
FILLERSTg Rework Die
ShearThermal Modulus
BondTemp
C C Cmin. PSI @ 25C WmC PSI
none -40 100 - 150 110 1700 0.2 60K
Ag, AlNnone
-25 150 - 200 160 2200 0.3 - 3.0 60K
Ag, AlNnone
45 160 - 220 170 2600 0.3 - 3.0 500K
Ag, AlNnone
98 160 - 250 170 3000 0.3 - 3.0 400K
Ag, AlNnone
180 325 - 400 350 4000 0.3 - 3.0 360K
None 145 200 - 230 210 3800 0.22 150K
None 280 350 - 450 400 4900 0.25 370K
Each row is a different polymerEach row is a different polymer
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SUBSTRATE CONDITIONING INITIAL BOND FINAL BONDCeramic 150oC, 1000 hrs. 2500 PSI 4800 PSI
Au-plated Ceramic
150oC, 1000 hrs. 3100PSI 4900 PSI
Al 150oC, 1000 hrs. 4100 PSI 4500 PSI
Ceramic85%RH, 85oC,
1000 Hrs.2500 PSI 1800 PSI
Au-plated Ceramic
85%RH, 85oC, 1000 Hrs.
3100 PSI 2600 PSI
Al85%RH, 85oC,
1000 Hrs.4100 PSI 3600 PSI
Ceramic-65oC to 150oC,
500 cycles2500 PSI 4000 PSI
Au-plated Ceramic
-65oC to 150oC, 500 cycles
3100 PSI 3700 PSI
Al-65oC to 150oC,
500 cycles4100 PSI 4800 PSI
Bond Strength of Die Attach Adhes.
Bonding: 180C/ 10sec, 135g; .080" x .080" Ni/Au Kovar
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Removal Options
• Heat element area
• Peel off parts
• Immerse assembly in solvent
• Remove parts
• Rinse in solvent
HEAT
SOLVENT Preferred for HDD work
Preferred for HDD work
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Wafer Lapping (thinning & polishing)
Attach wafer to lava stone with temporary adhesive.
Attach wafer to lava stone with temporary adhesive.
HDD Wafer
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Wafer Lapping Process
Wafer
Rotation
HolderLava Rock
TemporaryAdhesive
Grinding MediaGrinding Media
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Slicing1. Heat Bond Wafer
2. Slice into Rows
3. Debond with Solvent
Temporary adhesive
(sawing into rows)
ROW ofHeads beforesingulating
Rows formed after slicing
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AdhesivePaste
Lapping & Edge Polishing1. Dispense Adhesive
2. Mount Rows
3. Bond by heating
Automatic Dispenser- Speedline
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Temporary Adhesive
Row Bonding Step
Rotate 90o
with cut, or rough side facing up.
Rotate 90o
with cut, or rough side facing up.
(part of lapping & polishing)
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Debond in solvent
Rows are planarized/leveled/lapped
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Finished rows are sliced into head elements
Use temporary adhesive
Use temporary adhesive
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HDD Assembly
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Conclusions
• HDD Beats Moore’s Law and IC industry
• The breakthrough was GMR
• MEMS is playing a role
• Density limits have not been reached
• Photonics is being added
• Expect continuous density increases
73 GB
IBM