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The Ultra Small HDD for the

Mobile Applications

Akihiko Takeo, Kazuhito Shimomura, Jun Itoh

(HDD Development Dept., Core Technology Center,

Toshiba Corporation, Digital Media Network Company)

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OutlineOutline

� Target consumer for ultra-small HDD and the comparison

with the flash memories

� Mechanical feature of 0.85” HDD

- Shock durability –

� To keep the data capacity growth per year

- New perpendicular magnetic recording -

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TodayToday’’s HDD Capacity & Target Markets HDD Capacity & Target Market

Notebook PCs

Small size network servers

Car applications

40GB-200GB

(80-100GB/pl.)

2.5”

Cellular phones

MP3 players

2-10GB0.85” -1”

Mobile PCs

MP3 players

Portable video cameras & players

20-80GB

(40GB/pl.)

1.8”

Desktop PCs

Servers

HDD video recorders

200GB-600GB

(150-180GB/pl.)

3.5”

UseData CapacitySize

2.5“

1.8“

0.85“

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Size and Other Specifications of Small Memories

1.0” HDD size is the same as Compact Flash.

0.85” HDD size is the same as SD card.

Compact Flash SD card 1.8" HDD 1.0" HDD 0.85" HDD

Size Width 36.4 mm 24 mm 54 mm 36.4 mm 24 mm

Length 42.8 mm 32 mm 78.5 mm 42.8 mm 32 mm

Height 3.3 mm 2.1 mm 5 / 8mm 5 mm 5 mm

Shock Durability On data access 2000 G 1000 G 500 G 200 G 1000 G

Off data access 2000 G 1000 G 1500 G 2000 G 2000 G

Temperature On data access 0 ~ 60 °C 0 ~ 55 °C 0 ~ 60 °C 0 ~ 70 °C 0 ~ 70 °C

Off data access -25 ~ 85 °C -20 ~ 65 °C -40 ~ 80 °C -40 ~ 80 °C

Altitude On data access 24000 m 3000 m 3000 m 3000 m

Input Voltage 3.3 V 2.7�3.6 V 3.3 V / 5 V 3.3 V / 5 V 3.0 V

Transfer Rate 16.6MB/sec 12.5MB/sec 100MB/sec 10MB/sec 12.5MB/sec

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Mechanical Feature of 0.85Mechanical Feature of 0.85”” HDDHDD

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Hard Disk Drive (HDD) Structure

DiskHead

Voice Coil Motor for

head positioning

The sensitive parts of HDD

with external shock

(1) Disk winding and rolling

(2) Head suspension hitting on disk

Example of HDD mechanical roll

analysis by FEM simulation

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Load/Unload System

To avoid Head/Disk interaction by external shock, the heads frequently unload from

the disk surface to the ramp potion while idling.

= There are no damage on head/disk interaction when the head escapes on the ramp.

The shock durability while head unload state is higher than that while head on disk.

ramp

ramp

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Data Access Frequency with Mobile System

HDD

I/F

Buffer

Memory

Mobile Gadgetex. MP3 Player

Data size (1 song) 4–6 Mbyte

Play time 4–5 minutes (250-300 sec)

Buffer Memory size 64 Mbyte

HDD Data Transfer Rate 12.5 Mbyte/sec

HDD Data Access Time 0.4-0.5 sec

During 1 song play-out, the read head has to be on disk

for data readings for only 0.3% term of whole play-out

time.

Some of mobile gadget have large buffer memories to temporarily store the

HDD data, which minimize both the electric power and the head access

frequency on disk in HDD.

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0.85” HDD Structure

ramp

head suspension

disk

Even in the ultra small 0.85” HDD, the basic structure is the same as the

other large size HDD. JUST down-scaling!

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Shock Durability While Head Seeking

0.851.8

2.5

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Shock Durability [G]

Disk Size

Operating

Non-operating

The smaller radius disks are easy

to show the higher shock

robustness because of its small

rolling and light weight.

The shorter head suspension arm

length also shows higher shock

robustness.

Therefore small sized HDD could

achieve better shock durability.

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Short Summary

� 0.85” HDD was developed for the large data capacity

storage device which has the compatible size with the SD

card memories.

� The head Load/Unload system is applied for the higher

shock durability mobile device.

� The 0.85” small radius disk and the short head suspension

realize almost same shock durability specification as the

Flash card memory.

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Keep Data Capacity Growth

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What makes the areal density limit of

the magnetic recording?

Thermal Magnetization Fluctuation

If the thermal energy “kT” is larger

than the magnetic anisotropy energy

“KuV”, the particle magnetization is

always easy to flip and very unstable.

Based on previous many experimental

results, “KuV/kT” should be larger

than 60 to keep the magnetization

amplitude for 10 years.

KuV/kT > 60

0.000

0.500

1.000

1.500

2.000

2.500

-30.000 20.000 70.000 120.000 170.000

Magnetization angle

Energy

KuV

Ku : anisotropy coefficient

V : volume of particle

k : Boltzmann constant

T : temperature

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There are many

magnetic particles

in one data

recorded bit to get

fine S/N ratio

The larger data capacity

= Higher recorded density

= Smaller data bit size

= Smaller particle size

If KuV/kT becomes close to 60, …

Smaller volume with same Ku,

= x unstable magnetization

Smaller volume with higher Ku,

= o stable magnetization,

x hard to re-write the information with write head

The write head ability would define the limit of Ku. Then minimum

particle volume V will be limited to keep KuV/kT > 60.

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Longitudinal Recording System

Longitudinal recording field

generating between head gap

MR/GMR/TMR

Reader

Ring Write

Head Yoke

Medium particle orientation:

� 2D random in disk plane

� About 50 particles in one data bit

to keep fine S/N ratio

Write Ability:

Maximum recording field near gap

=0.5 x head yoke magnetic flux density

Higher linear density = thermally unstable

Lower linear density = thermally stable

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Perpendicular Recording System

NS

NS

NS

NS

SN

SN

SN

Perpendicular

Recording Layer

Soft-magnetic

Under Layer

Reader

Perpendicular

Single Pole

Writer

Perpendicular

Write Field

Write Ability:

Maximum recording field near gap

=1.0 x head yoke magnetic flux density

= 2 times of LMR field limit

Medium particle orientation:

� Single orientation perpendicular to

disk plane

� About 30 particles in one data bit

to keep fine S/N ratio

Higher linear density = thermally stable

Lower linear density = thermally unstable

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Key of Success for Perpendicular Recording HDD

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

-20000 -15000 -10000 -5000 0 5000 10000 15000 20000

H [Oe]

Mt [

mem

u/c

m2]

10K

50K

100K

200K

300K

e.x. M-H loop of low squareness medium

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

-20000 -15000 -10000 -5000 0 5000 10000 15000 20000

H [Oe]

M [

10

-4e

mu

]

10K

50K

100K

200K

300K

Remanence of high Hn medium keeps good thermal stability

under low density demagnetized field

Temperature dependence of M-H loop of CoPtCrO Media

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1.2Mbit/inch (1200kbit/inch) linear density achieved with 137nm

magnetic write track width head.

High Density Recording beyond �MBPI

Over 1MBPI Performance

-6.0

-5.5

-5.0

-4.5

-4.0

-3.5

0.9 0.95 1 1.05 1.1 1.15 1.2 1.25 1.3 1.35

BPI [MBPI]

BE

R

MWW=137nm,

uMRW=75nm

INTERMAG2005

MWW=184nm,

uMRW=97nm

Longitudinal

recording limit

Required minimum

Bit-Error-Rate

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Toward Higher BPI

80

100

120

140

160

600 800 1000 1200

Linear Density (kBPI)

Track Density (kTPI)

Longitudinal

HDDPerpendicular

HDD

60Gbpsi

80Gbpsi

100Gbpsi

120Gbpsi

140Gbpsi

BPI/TPI=6

BPI/TPI=8

BPI/TPI=10

80

100

120

140

160

600 800 1000 1200

Linear Density (kBPI)

Track Density (kTPI)

Longitudinal

HDDPerpendicular

HDD

60Gbpsi

80Gbpsi

100Gbpsi

120Gbpsi

140Gbpsi

BPI/TPI=6

BPI/TPI=8

BPI/TPI=10

Recording track

Recording bit

Track Density

Lin

ear

Bit

Den

sit

y

Perpendicular recording HDD tends to higher BPI/TPI ratio than

previous longitudinal HDD, which means the perpendicular HDD

makes higher data transfer rate more easily.

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8GB / 10GB 0.85” HDD Basic Specification

(Proto-type released in CES2006)

4GB

commertial

product

8GB

Proto-type

10GB

Proto-type

Disk 1 platter 1 platter 1 platter

Head 2 heads 2 heads 2 heads

Areal Density 84 Gbpsi 159 Gbpsi 198 Gbpsi

Track Density 113 kTPI 165 kTPI 165 kTPI

Linear Density 743 kBPI 960 kBPI 1195 kBPI

Recording System Longitudinal Perpendicular Perpendicular

Density Increment - 189% 236%

HOT-CHIPSC�Year88

MR Head,ID-less

CDR 30%/YearThin Film Head

Glass Media

MIG Head, Sputtered Media

FDB Motor 30GB/Disk(2.5” Disk)

100%/Yea

r

Areal Density

89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09

8060

AFC Media

Oriented Media 100

35-40%/Year

10 11 12 13

1000

100

1

[Gb/inch2]

PRML

GMR10

60%/Year

40

New Technologies

Ramp Load

Perpendicular Recording& TMR Head

CPP GMR Head

HDD Areal Density TrendHDD Areal Density Trend

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Summary

� 0.85” HDD was developed for the large data capacity

storage device which has the compatible size with the SD

card memories.

� To utilize the ramp load system & temporary buffer

memories, 0.85 HDD shock durability is almost cleared

about 2000G on end-user operating.

� Applying the perpendicular recording technology, 8/10GB

proto type HDDs were realized. This technology will keep

areal density growth over 35%/year in coming 5-10 years.