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