Suspension Design Progression for Increasing Shock Performance Jacob Bjorstrom Sr. Product Design Eng. Hutchinson Technology September 22, 2004 DISKCON

Suspension Design Suspension Design Progression for Increasing Progression for Increasing

Shock PerformanceShock PerformanceJacob BjorstromJacob Bjorstrom

Sr. Product Design Eng.Sr. Product Design Eng.Hutchinson TechnologyHutchinson Technology

September 22, 2004September 22, 2004

DISKCON 2004

Hutchinson Technology Inc., September 22, 2004Hutchinson Technology Inc., September 22, 2004 22

AgendaAgendaShock TerminologyShock Terminology

A Brief History of Mobile Shock A Brief History of Mobile Shock PerformancePerformance

Suspension/HGA Shock DesignSuspension/HGA Shock Design• Loadbeam, flexure, sliderLoadbeam, flexure, slider

Load/Unload Shock DesignLoad/Unload Shock Design

Drive Design ImpactsDrive Design Impacts

ConclusionsConclusions


TerminologyTerminologyShock - Shock - a sudden disturbance a sudden disturbance induced on the hard driveinduced on the hard drive

G -G - measure of gravitational measure of gravitational acceleration, the number of G’s is acceleration, the number of G’s is the magnitude of the shock eventthe magnitude of the shock event

Pulse width -Pulse width - length of time that a G length of time that a G load is appliedload is applied

Op-Shock -Op-Shock - a shock event applied a shock event applied while the drive is spinning with the while the drive is spinning with the slider on the diskslider on the disk

Non-op Shock -Non-op Shock - a shock event a shock event where the slider is parked in it’s where the slider is parked in it’s resting position, typically in a mobile resting position, typically in a mobile drive this would be off the disk on drive this would be off the disk on the load/unload ramp.the load/unload ramp.

Gram - Gram - downwarddownward force supplied by force supplied by the suspension to hold the slider on the suspension to hold the slider on the diskthe disk

G/gram -G/gram - suspension parameter suspension parameter used to determine liftoff point of the used to determine liftoff point of the slider from the disk, for a given gram slider from the disk, for a given gram loadload

0

50

100

150

200

250

0 0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014 0.0016 0.0018 0.002

time (sec)

G's

Pulse Width = 1.0ms

Shock Load = 200G


Mobile TimelineMobile Timeline

3.0” FF

41 G/gram

2.5” FF

61 G/gram

2.5” FF

83 G/gram

1.0” FF

160 G/gram

0.85” FF

707 G/gram

1995 1997 1999 2001 2005

0.85” FF

394 G/gram

2003

17X Improvement in Suspension G/Gram


History of RequirementsHistory of RequirementsHigh End Mobile Shock Specifications

0

500

1000

1500

2000

2500

1994 1996 1998 2000 2002 2004 2006 2008 2010

Year

G, S

pe

c L

imit micro-HDD non-op shock

micro-HDD op-shock

mobile non-op shock

mobile op-shock


Four Major Drive Components Four Major Drive Components Affect Shock PerformanceAffect Shock Performance

2. Magnetic Disks

Recording Head

Disk Drive3. Actuator

4. Suspension

Assembly 1. Drive Case


Achieving Higher ShockAchieving Higher ShockAt the suspension level, the key is to At the suspension level, the key is to reduce the effective load beam massreduce the effective load beam mass

– Mass of the HGA past the bend radiusMass of the HGA past the bend radius

The further the mass is from the bend The further the mass is from the bend radius, the more detrimental it is to shock radius, the more detrimental it is to shock

LOADBEAM SLIDER FLEXUREARM / MOUNT PLATE

BEND RADIUS

EFFECTIVE MASS


Beam Design and Beam Design and Material ThicknessMaterial Thickness

Thin railed beams have less massive cross-Thin railed beams have less massive cross-sections, which are ideal for shocksections, which are ideal for shock

Thick beam (101 m) cross-section

Thin railed beam (20 m) cross-section


Mass ReductionMass ReductionBest for shock with acceptable resonance Best for shock with acceptable resonance

Allow for strategic mass reductionAllow for strategic mass reduction

+14% Shock

+5% B1

-5% T1

-9% Sway


Advanced Concept:Advanced Concept:Laminate BeamsLaminate Beams

Offers resonance Offers resonance improvement over improvement over thin beam designs thin beam designs while keeping high while keeping high shock performanceshock performance


Effective Beam LengthEffective Beam Length

Effective beam length is the Effective beam length is the distance from the arm / swage plate distance from the arm / swage plate edge to the load pointedge to the load pointA shorter distance reduces A shorter distance reduces suspension mass, and increases suspension mass, and increases shock and resonance performanceshock and resonance performanceTradeoffs are space constraints and Tradeoffs are space constraints and increased risk of gram load lossincreased risk of gram load loss

9.3 mm

4.35 mm


Flexure Progression: Flexure Progression: Hub Clearance and MassHub Clearance and Mass

Past Present Future


Slider Size vs. G/GramSlider Size vs. G/GramThe smaller the slider, the higher the G/gram for a given suspensionThe smaller the slider, the higher the G/gram for a given suspensionThe G/gram delta between sliders increases as the slider becomes a The G/gram delta between sliders increases as the slider becomes a larger portion of the effective masslarger portion of the effective mass

Slider Effects on HGA G/gram

0

100

200

300

400

500

600

700

800

0 250 500 750 1000 1250 1500

Suspension Only G/gram (no slider)

HG

A G

/gra

m

2001

2003

2005

300 G/gram

30 G/gram

Pico

Femto


Slider Size vs. Total G’sSlider Size vs. Total G’sThe smallest head is not necessarily the best for total The smallest head is not necessarily the best for total HGA shock performance when accounting for gram load HGA shock performance when accounting for gram load and slider negative air bearing pressureand slider negative air bearing pressure

Maximum Total HGA Op-Shock by Slider Size

0

500

1000

1500

2000

2500

0 250 500 750 1000 1250 1500

Suspension only G/gram (no slider)

Max

imu

m H

GA

Lif

toff

Val

ue

(G's

)

2001

2003

2005

Pico

Femto


Shrinking Form FactorShrinking Form FactorAs the drive size decreases, the suspension becomes a As the drive size decreases, the suspension becomes a large factor on drive level shock performancelarge factor on drive level shock performanceSmall form factor drives benefit from both increased Small form factor drives benefit from both increased suspension level G/gram and improved drive dynamicssuspension level G/gram and improved drive dynamics

Suspension's % Contribution to Total Drive Op-Shock SpecDrive Size vs. Suspension % Contribution

0%

20%

40%

60%

80%

100%

120%

0.511.522.533.5

Drive Form Factor (inches)

Su

spen

sio

n's

% C

on

trib

uti

on

to

Dri

ve

Op

-Sh

ock

Sp

ec

.85" Expected Range


Non-op ShockNon-op ShockShock failure is caused by a large deflection of the head and gimbal during shock. Parameters that affect shock performance are:

1. Ramp design

2. Limiter design

3. Gimbal design

SuspensionGimbal & Slider

Arm

Disk

Ramp Headlift


Motion Control: Motion Control: LimitersLimiters

No limiters engaged(large deflection of slider and gimbal)

Ramp and T-bar limiters engaged(slider and flexure motion restrained)

Slider

Suspension

Ramp

Slider

SuspensionRamp

Limiters


HeadliftsHeadliftsParking the slider off the disk Parking the slider off the disk prevents shock damageprevents shock damageMass reduction at the tip of the Mass reduction at the tip of the suspension provides the best suspension provides the best results for increased G/gram liftoffresults for increased G/gram liftoffNew headlift concepts offer twice New headlift concepts offer twice the stiffness and half the massthe stiffness and half the mass

Actual SEM

Standard Offset Form Headlift

New Continuous Rail Form Headlift


ResultsResults

Large displacement and probable

disk/head damage

Mainstream micro-HDD suspension

HTI leading edge micro-HDD suspension

Shocked at: 1000 G’s 1 ms pulse

No separation between disk and slider


Systems ViewSystems View

While the suspension is a large factor in drive shock performance, all components in the system must work together for optimal performanceThe same suspension can have different shock performance in different drive designs

Desktop Program #1300G @ 1.0ms

0

0.5

1

1.5

2

2.5

3

3.5

100 125 150 175 200 225 250 275

G/gram

Cu

mm

. Lif

toff

(m

m)

Desktop Program #2300G @ 1.0ms

0

0.5

1

1.5

2

2.5

3

3.5

100 125 150 175 200 225 250 275

G/gram

Cu

mm

. Lif

toff

(m

m)


ConclusionsConclusions

Shock has become a primary differentiator Shock has become a primary differentiator in mobile drive performance.in mobile drive performance.

New HTI suspension designs continue to New HTI suspension designs continue to expand the current drive level shock expand the current drive level shock performance envelope.performance envelope.

To maximize drive level shock To maximize drive level shock performance, all components must be performance, all components must be designed in harmony with one another.designed in harmony with one another.

Documents

Suspension Design Progression for Increasing Shock Performance Jacob Bjorstrom Sr. Product Design Eng. Hutchinson Technology September 22, 2004 DISKCON