10.04.2003 Cleanroom garments - Techtextil 1

Basic requirements of cleanroom garments

Basic requirements of cleanroom garments

Jan LaperreCENTEXBEL (B)

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Basic requirements of Cleanroom garments

Co-authorsP. Lemaire, Centexbel (B)J. Paasi, VTT (FIN)G. Coletti, University of Genova (I)L. Fast, SP (S)C. Vogel, STFI (D)A. Brjesson, agb-konsult (S)J. Smallwood, Electrostatic Solutions (UK)T. Peltoniemi, Nokia (FIN)G. Reina, Celestica (I)

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Roadmap

CleanroomsEssential requirements of cleanroom garments

LintingESD-performance

Textile materials and garment design

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Cleanrooms

What:Areas with specified number of particles per unit volume

Where:Microelectronics industryPharmaceutical industrybiotechnological industryFood & beverages

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Cleanrooms classificationISO 14644-1

0.1 10

1

2

3

4

5

6

7

ISO Class 9

ISO Class 8

ISO Class 7

ISO Class 6

ISO Class 5

ISO Class 4

ISO Class 3

ISO Class 2

ISO Class 1

Log(

parti

cles/

m3 )

Particle size (m)

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Classification versus activities

ISO 4:High speed video

duplicationGlass lamination

ISO 2Semi-conductor

manufacturingPharmaceutical products

ISO 3Compact disk

manufacturingOptical manufacturing

ISO 1Latest wafer and chip

manufacturingHard disk manufacturing

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Cleanroom garments

Why necessary?Humans are broad-spectrum particle and aerosol generatorPrevent contamination of cleanroom by cleanroom worker (barrier-function)

DangerGarments can shed particles (linting)Garments can damage microelectronic components through ESD events

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Particles generated by humans

Skin flakes: average size: 20mNumber: 500.000 1.000.000/min moderate operation

BacteriaBiological

Chemicals

Cellulosic, ...Fibers

Silica dustParticulateStreet clothsBacteria, virussesBiological

Skin flakes, hair, cosmeticsParticulateOperatorType of contaminationClassificationSource

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Performance requirements

Particulate barrier propertiesGarment cleanlinessESD performance

ComfortDurability (sterilisation)

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Garment lintingHelmke drum-test & Gelboflex

Helmke drum test Gelbo-flex test

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Linting propensity

0.19

-0.3

0.3

- 0.5

0.5

- 1.0

1.0

- 3.0

3.0

- 5.0

> 5.

0

m ic ro fila m e n t p o lye ste r

p o lye ste r - c o tto n

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

microfilament polyesterpolyester - cotton

particle size (m)

num

ber o

f par

ticle

s pe

r min

ute

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MeasurementsCleanroom facilities in Centexbel

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Cleanroom garmentsMaterials and construction

MaterialsReusable materials:

Densily woven polyester materialKnitted materials (less critical areas)Tri-laminates

Non-woven materialsTyvek

ConstructionSeams

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ESD-failure of electronic components

Failure rate30-50% of all failures due to electrical overstressDecrease of component dimensions increases ESD sensitivity

Failure modesDirect discharge from operators body (HBM)Discharge from a charged device to ground (DM)Discharge from a charged cleanroom garment

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ESD performanceFailure modes of components

Human body model0.1 10 A peak current100 200 ns duration

DEVICE

Bodycapacitance

Bodyresistance

Surfaceresistance

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ESD performanceFailure modes of components

Device model5 10 A peak current1 - 2 ns duration

DEVICE

Devicecapacitance

Surfaceresistance

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ESD-performanceSensitivity of electronic devices

500 8000LEDs200 1500Laser diodes50 150Flat panel displays, CCDs10 100MR heads

Typical HBM sensitivity (V)

Technology

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Requirements of ESD garments

Garments should:Low propensity for triboelectric chargingLow resistance for fast dissipation in order to avoid charge accumulationHigh resistance to slow down the charge decay and to limit the energy transfer in a dischargeTotal suppression of E-fields from charge on clothing

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Cleanroom garmentsESD-measures

Material designConductive yarnsGridstructures (5 by 5, 2 by 2 mm)

Garment designElectrical conduction garmentEarthing of the operator

Cleanroom designConductive shoe wearEarthed floor

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Standard testmethods

Point to point resistance according to IEC 61340-5-1

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Standard testmethods

Standard testmethods are resistive measurementsOriginally developed for homogeneous materials suited for inhomogeneous materials ?Charging propensity of material is not taken into accountEffect of grounding is not evaluated

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ESTAT project

Aims to:Provide a basis for understanding charging and discharging behaviour of complete system (operator clothing environment)Study test methodologies and performance requirements for protective ESD garments

Project website: http://estat.vtt.fi

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ESD performance requirements

Low requirements for the electrostatic performance, some normal garments may pass the requirements

ESDS with > 200 VClass 3

Normal protection level corresponding to typical stat-of-the-art ESD garments

ESDS with > 100 VClass 2

High protection level, special recommendations for grounding, undergarments etc...

Ultrasensitive devicesClass 1

Required garment performance

Performance targetGarment class

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Conclusion

Cleanroom garments:A growing market

But:Stringent performance requirements