8/23/2006
Diskcon '061
Measurement And ReductionMeasurement And Reductionofof
Particulate ContaminationParticulate Contaminationin HDDin HDD
Phil LeiCarl Newberg
Chris Schreiber
Magnecomp Precision Technology
September, 2006
8/23/2006
Diskcon '062
OverviewOverview
• The effect of particles in Hard Disk Drives• How clean is clean enough• Metrology for monitoring cleanliness• Realistic specifications• Monitoring the right things• How do we know the data is correct• What other information can LPC data provide• Will future LPC monitoring be in-sync with HDD
technology advance
8/23/2006
Diskcon '063
The effect of particles in Hard Disk DrivesThe effect of particles in Hard Disk Drives• General
– They are mobile and transferable– Variable size– Most are easy to clean but some
are very sticky• Hard particles
– Scratch (complete damage)– Hard error
• Soft particles– Smear on media– Soft error (re-writable)
8/23/2006
Diskcon '064
How Clean Is Clean Enough?How Clean Is Clean Enough?
Emerging Recording Technologies Demand Enhanced Controls
• Robust Designs – Interface, Components, HDD Process
• Higher Cleanliness – Tighter Requirements, Controls, Metrology
HDD Trends
8/23/2006
Diskcon '065
Measurement TechniquesMeasurement Techniques• Liquid Particle Counting (LPC)
Extraction Method – Varies By Customer• Ultrasonic Power & DI water
– Power density, frequency, extraction time, etc.• Dry Particle Counting SEM/EDS
– Tape Extraction– Swab Extraction
• Other Extraction Techniques (non-HDD)– Spray Extraction– Non-ultrasonic liquid (swishing)
• Measurement Method Definition• Calibration and Correlations• Ultrasonic tank and LPC sensor• Size of Particulate• Differential counts vs. cumulative counts
• Particle Type Characterization• Extraction Methods• SEM/EDS Spectra
8/23/2006
Diskcon '066
Particle Cleanliness CriteriaParticle Cleanliness Criteria
• Particle size– 2.0um– 0.6um/0.5um– 0.3/0.2um– Future trend?
• Particle Counts– Differential counts– Cumulative counts– Per unit surface area– Per part
• Particle Type– Hard particles– Semi-hard particles– Soft particles
• Related to Particulate– Erosive materials– Corrosion induced
Particulate
8/23/2006
Diskcon '067
Realistic SpecificationsRealistic SpecificationsCase #1: Different Cleanliness, Same Cleanability
0
1,000
2,000
3,000
4,000
1X 2X 3X 4X 5X
LPC
Case #2: Different Cleanliness, Different Cleanability
0
1,000
2,000
3,000
4,000
1X 2X 3X 4X 5X
LPC
Case #3: Different Cleanliness, Different Cleanability
0
1,000
2,000
3,000
4,000
1X 2X 3X 4X 5X
LPC
Case #4: Same Cleanliness, Different Cleanability
0
1,000
2,000
3,000
4,000
1X 2X 3X 4X 5X
LPC
Different Cleanliness
Same Asymptote Different Asymptote
Reasonable Specification?
8/23/2006
Diskcon '068
What Are You Really Monitoring?What Are You Really Monitoring?
LPC Data is Dependant Upon– Absolute Cleanliness of the Parts
• Samples Representative of Mfg. lots
– Sensor’s Ability to Detect Particles (Machine)• Resolution• Calibration & Gage
– Uniform Test Procedure (Method)• Sensor Calibration • Minimize Human and Environmental Factors• Sensor Calibration• Extraction Power & Procedure
8/23/2006
Diskcon '069
How Do You Know Your Data Is Correct?How Do You Know Your Data Is Correct?
• Particle size distribution
3
1size
cnts ∝ bsizekcnts +⋅= )log()log(Where k is approximately -3.
Abnormal!Abnormal!
PMS: Beal et al.
8/23/2006
Diskcon '0610
What Else Can LPC Data Tell You?What Else Can LPC Data Tell You?
• Base Material Property Variability– Variations Between Raw Material Sources
• SST Melt & Re-Roll lots• Dielectric Differences i.e. PI vs. Acrylic Coverlay
– Vendor Process Induced Variations– Internal Processing Variations
• Other Unknown Process Factors– Tooling Changes– Particle Type Change– Improper Handling & Transportation
8/23/2006
Diskcon '0611
Particle Type CategorizationParticle Type Categorization
• Hard particle type
Silica, silicate, alumina, carbide, diamond, etc.
• Semi-hard particle type
SST 3xx series, SST 4xx series, other Fe-based, etc.
• Other particles
Fiber, talc, magnetic, etc.
Media scratches, Media scratches, head damage, etc.head damage, etc.
Erasure, smear, minor scratches, etc.
8/23/2006
Diskcon '0612
Particle Extractions By Ultrasonic PowerParticle Extractions By Ultrasonic Power
U/S Power
U/S Frequency
Extraction Time
• 200 watts
• 300 watts
• 350 watts
• 30 sec
• 60 sec
• 120 sec
• 68 kHz
• 132 kHz
3-factor DOE
• How much U/S power to use?
• What is the best U/S frequency?
• How long to extract?
8/23/2006
Diskcon '0613
Extraction Power, Time & Frequency FactorExtraction Power, Time & Frequency FactorLP
C
5X4X3X2X1X
1600
1400
1200
1000
800
600
400
200
0
U/S_Power200W300W350W
Multiple Extraction LPC: U/S Power Effect
LOG/
LOG
Curv
e Sl
ope
120sec60sec30sec
-2.50
-2.75
-3.00
-3.25
-3.50
-3.75
Frequency132kHz68kHz
LOG/
LOG
Curv
e Sl
ope
350W300W200W
-2.50
-2.75
-3.00
-3.25
-3.50
-3.75
Frequency132kHz68kHz
Frequency effect has the most significance!Frequency effect has the most significance!
8/23/2006
Diskcon '0614
Extraction Time and Extraction PowerExtraction Time and Extraction Power
Extraction Power and Time Factor
0
500
1,000
1,500
2,000
2,500
3,000
3,500
30 sec 60 sec 120 sec
Extraction Time
0.2u
m L
PC (D
iffer
entia
l Cou
nts)
200W 300W 350W
8/23/2006
Diskcon '0615
Cleanliness Control RoadmapCleanliness Control RoadmapCustomer
Cleanliness Requirements
R&D, Design
Manufacturing
Final Products QA for Outgoing
Product/Tooling Robust Design for Better Cleanliness
Material Cleanliness Characteristics Qualifications
Reduced Handling
Tooling Cleanliness
Clean room Facility and Commodity Cleanliness
LPC Test Method Optimization
Standardized Data Reporting
Final Washing System Optimization
Supplier Cleanliness Control(LPC spec for components)
Best-in-Class Methods
Feedback from Customer Results
8/23/2006
Diskcon '0616
Future LPC Monitoring in HDDFuture LPC Monitoring in HDD• Smaller Than 0.2µm Particle Size?
• Lower counts
• More sophisticated particle segregation– More complex analysis tool and procedure– More comprehensive procedure
• Adoption of one unified HDD industry measurement procedure
• Uniform specification criteria based upon, for example asymptote
8/23/2006
Diskcon '0617
SummarySummary
• New Recording Methods Require More Stringent Cleanliness
• Enhanced Focus on HPA & SST Particulate
• Current Test Methods Possess Erosive Background That Overlap Future Targets
• Attaining Effective Cleaning Without Altering the Delicate 0.1 degree Static Attitude and 0.02 Gram Sigmas, on Today’s Products Pose Significant Challenges
• LPC Trends are Challenging the Metrology