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10.04.2003 Cleanroom garments - Techtextil 1
Basic requirements of cleanroom garments
Basic requirements of cleanroom garments
Jan LaperreCENTEXBEL (B)
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10.04.2003 Cleanroom garments - Techtextil 2
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
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