clean production in an industrial environment
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TRANSCRIPT
Clean production in an industrial environment
Anton de Jong, Anton Duisterwinkel
2011-03-11
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CONTENTS
1. Introduction
2. Systematic approach of assessing risks
3. Contamination control
- Prevention
- Cleaning
- Detection and Qualification
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Why bother?
Cleanliness becomes more important for the High Tech industry, e.g.
Semiconductor (ASML, ASMI, supply chains)
Analytical instruments, mass flow controllers of Bronkhorst; FEI
Automotive (Nedcar, etc.)
Medical
Space (ESA, NASA)
Solar
Lighting (OLED’s), electronics
Important:
How to produce cleanly in a cost effective way
How to check the quality of products
Essential: keep the balance between costs of risks and the
costs that control of the risks will bring
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Clean production of high tech products
Product Company cleaniliness Remark
particles organic outgassing
cont. vacuum
Analytical flowmeters Bronkhorst yes yes no oxygen safety
(EUV) Lithography ASML yes yes yes optical performance
Electron Microscopy FEI yes yes yes opitcal performance
Space instruments TNO Space, ESA yes yes yes optical performance
Solar cell prodution OTB,….. yes yes no/yes yield, lifetime
OLED, OPV Holst yes yes no/yes yield, lifetime
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Contaminants: what and where from?
Object surface
Films
Oil, grease (production), Food, Biofilms
Molecular
Water (condensate), Hydrocarbons (air), NH3, silicones (production)
Particles
Organic particles (pollen, micro-organisms, hairs, fibers, …, > 1 µm)
Metallic particles (due to production, abrasion, ageing, > 1 µm)
Oxidic: Sand, dirt, asbestos (environment, glass treatment, abrasion)
Soot/smoke, salt, (NH4)2SO4 (condensation: < 1 µm)
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Cleanliness: does it exist?
Example 1: Oxygen application;
maximum concentration organic material (< 66 mg C/m2)
Example 2: Clean surface in food industry, allowed number of colony’s?
2.5 CFU/cm2, or 25000 per square meter!
Example 3: Clean assembly: ISO Class 4, allowed number of particles?
10000/m3 (of 0.1 µm or larger);
352/m3 (of 0.5 µm or larger)
‘Dirty’, but fit for purpose !
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Clean is dirty …
to the extent that functionality is not hindered.
Rule 1 ‘Clean must defined’- Typically: no gross (visual) contamination- Definitions on particles (size, number) and molecules
Rule 2 Testing method must be defined- who and when determined- exact description of method
Rule 3 Responsibility, liability must be defined
What is clean?
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CONTENTS
1. Introduction
2. Systematic approach of assessing risks
3. Contamination control
- Prevention
- Cleaning
- Detection and Qualification
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Systematic approach for contamination control:
1. Products and production scheme
2. Assessment of the risks (FMEA)
3. Solving of the most important risks
Example:
Product : example complex assy
QD1:
Mat. Cer.
QD1:
Mat. Cer.
QD1:
Mat. Cer. 028 t=..
Weld water
hoses to
cooler body
001
Material for
cooler body
003 t=..
Milling002
fQ
004, t=..
Intermediate
Wet clean
007 t=..
Store
QD1:
Mat. Cer.
023
Water Hose 024
fQ
026, t=..
Intermediate
Wet clean
027 t=..
Store
QD1:
Mat. Cer.
029
Filament 030
fQ
032, t=..
Intermediate
Wet clean
033 t=..
Store
QD1:
Mat. Cer.
035
Screws 036
fQ
038, t=..
Intermediate
Wet clean
039 t=..
Store
041
Vac. Bolts 042
fQ
044, t=..
Intermediate
Wet clean
008 t=..
Intermediate
Wet clean
001
Material for
backplate
002
fQ
003 t=..
Milling004, t=..
Intermediate
Wet clean
t=..
Transport to
Louwers
005 t=..
Melt in
electrical
feedthroughs
002
lfeedthrough
s
t=..
Transport to
A
004, t=..
Intermediate
Wet clean
002
Gas hoses
005 t=..
Weld gas
hoses to
backplate
002
Press
008 t=..
Intermediate
Wet clean
t=..
Transport to
T
Supplier: B
T = ..
Supplier: B
T = ..
Supplier: C
T = ..
Supplier: A
T = ..
Supplier: D
T = ..
Supplier: A
T = ..
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What kind of product?
Simple mono part
Simple assembly wet cleanable
Assembly not wet cleanable
Complex assembly sensitive not wet cleanable and sensitive to heat
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Step 1: Product /production analyses
Goal: Define the how “dirty/clean” the (end)product may be in the
different production steps.
1. Describe the product and production steps
2. Describe the requirements to the end product and the intermediate
steps
3. Define where contamination is critical for the next step in the
process
4. Define the contamination sources in the process
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Strategy for the control of a production process
• Choice and sequence of the production steps
• Detail for the production steps
Example:
Product : example complex assy
QD1:
Mat. Cer.
QD1:
Mat. Cer.
QD1:
Mat. Cer. 028 t=..
Weld water
hoses to
cooler body
001
Material for
cooler body
003 t=..
Milling002
fQ
004, t=..
Intermediate
Wet clean
007 t=..
Store
QD1:
Mat. Cer.
023
Water Hose 024
fQ
026, t=..
Intermediate
Wet clean
027 t=..
Store
QD1:
Mat. Cer.
029
Filament 030
fQ
032, t=..
Intermediate
Wet clean
033 t=..
Store
QD1:
Mat. Cer.
035
Screws 036
fQ
038, t=..
Intermediate
Wet clean
039 t=..
Store
041
Vac. Bolts 042
fQ
044, t=..
Intermediate
Wet clean
008 t=..
Intermediate
Wet clean
001
Material for
backplate
002
fQ
003 t=..
Milling004, t=..
Intermediate
Wet clean
t=..
Transport to
Louwers
005 t=..
Melt in
electrical
feedthroughs
002
lfeedthrough
s
t=..
Transport to
A
004, t=..
Intermediate
Wet clean
002
Gas hoses
005 t=..
Weld gas
hoses to
backplate
002
Press
008 t=..
Intermediate
Wet clean
t=..
Transport to
T
Supplier: B
T = ..
Supplier: B
T = ..
Supplier: C
T = ..
Supplier: A
T = ..
Supplier: D
T = ..
Supplier: A
T = ..
B
Example:
Product : example complex assy
QD1:
Mat. Cer.
QD1:
Mat. Cer.
QD1:
Mat. Cer. 028 t=..
Weld water
hoses to
cooler body
001
Material for
cooler body
003 t=..
Milling002
fQ
004, t=..
Intermediate
Wet clean
007 t=..
Store
QD1:
Mat. Cer.
023
Water Hose 024
fQ
026, t=..
Intermediate
Wet clean
027 t=..
Store
QD1:
Mat. Cer.
029
Filament 030
fQ
032, t=..
Intermediate
Wet clean
033 t=..
Store
QD1:
Mat. Cer.
035
Screws 036
fQ
038, t=..
Intermediate
Wet clean
039 t=..
Store
041
Vac. Bolts 042
fQ
044, t=..
Intermediate
Wet clean
008 t=..
Intermediate
Wet clean
001
Material for
backplate
002
fQ
003 t=..
Milling004, t=..
Intermediate
Wet clean
t=..
Transport to
Louwers
005 t=..
Melt in
electrical
feedthroughs
002
lfeedthrough
s
t=..
Transport to
A
004, t=..
Intermediate
Wet clean
002
Gas hoses
005 t=..
Weld gas
hoses to
backplate
002
Press
008 t=..
Intermediate
Wet clean
t=..
Transport to
T
Supplier: B
T = ..
Supplier: B
T = ..
Supplier: C
T = ..
Supplier: A
T = ..
Supplier: D
T = ..
Supplier: A
T = ..
B
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Failure Mode Effect Analysis
Step 2: Make a list of all failure modes
1. Severity � How big is the negative effect
(Higher score if it is more severe)
2. Occurrence � How often does is happen
(Higher score with increasing frequency)
3. Detection/prevention � How difficult is it to detect the failure
(Higher score if it is more difficult to detect)
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FMEA (2)
FMEA score Ernst Voorkomen Detectie
1 geen nooit zeker
2
1
minimale gevolgen voor product (alleen kritische klanten) vrijwel nooit
zeer waarschijnlijk
3 minimale gevolgen voor product (50 % van klanten) laag waarschijnlijk
4
2 gemiddelde gevolgen voor product af en toe boven gemiddeld
5 grote gevolgen voor product met tussenposen gemiddeld
6
3
kleine schade aan productieapparatuur regelmatig laag
7 schade aan productieapparatuur erg regelmatig erg laag
8
4
grote schade aan productieapparatuur vaak onwaarschijnlijk
9 wettelijke normen erg vaak zeer onwaarschijnlijk
10
5 mensveiligheid extreem vaak niet mogelijk
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FMEA (3)
Calculate the “Risk Priority Number” for each failure mode
RPN = effect x occurrence x Detection
Sort on RPN
Example:
Failure mode severity occurance detection RPN
failure in cleaning unit 10 3 8 240
failure in contamination verification 8 2 9 144
delivery of dirty tubing 3 2 9 54
fingerprints on product 2 4 3 24
FM4
FM5
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CONTENTS
1. Introduction
2. Systematic approach of assessing risks
3. Contamination control
- Prevention
- Cleaning
- Detection and Qualification
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Solving the risks: Contamination control
Is a systematic effort to control contamination to such a level that it
does not disrupt functionality of a process or product by
Prevention
Clean design some major principles
Clean environment this afternoon
Clean assembly this lecture
Cleaning
Overview details this afternoon
Detection and Inspection
Detection (lab) NOT
Inspection (fab) this lecture
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Contamination control: Prevention
1. Design rules
Source controlClean in (checked!); filtering; easy to clean oils etcetera
Design of instruments and processes
Accessibility; flow away from critical surfaces; hanging
Materials selection and development(electro)polished materials; controlled contacts; non-stick coating
Optimization of process conditionsAdd chemicals that remove dirt; prevent hot spots
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Contamination control: Prevention
2. Clean environment
Separate from normal production area
Closed room where only qualified personnel can enter
Cleanroom necessary for very critical parts only
For packaging of critical parts: clean bench or flow bench
Hang overcoats and gloves near the entrance door.
Place extra gloves boxes near baths and clean bench.
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Contamination control: Prevention
3. Clean assembly
Control the cleanliness of incoming materials and parts:
Clean raw materials like bar, rod and profiles
before processing
Plastics will have oily residues, silicones and
plasticizers on the surface from manufacturing
All third party components must be qualified,
even if they are claimed to be ‘clean’
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Contamination control: Prevention
3. Clean assembly
Manufacturing of components by machining:
Do not use oil based cutting fluids or use vegetable oils
Use separate tools for manufacturing especially cleaned for vacuum
All surfaces must be machined
Last machining step preferably dry or with ethanol or IPA as cutting fluid
prevents burial of cutting fluid in surface
Clean the parts in the same run
Beware of explosion risk and human safety!
After machining immediately blow off with nitrogen or dry, pressurized, oil
free air for removal of excessive cutting fluid.
Wipe parts with lint free cloth soaked with ethanol or IPA
Store under clean conditions for future cleaning
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Contamination control: Prevention
3. Clean assembly
Clean Handling of clean parts
Handling of objects only by qualified personnel
Always wear overcoat and clean gloves (powder free!)
Limit touching of the part to a minimum.
After contact with contaminated objects put new gloves on.
Do not hesitate to change your gloves if you suspect they got
contaminated, it can save you a lot of work!
Make sure extra gloves are available
Put clean objects in a clean bench on aluminium foil
Use a flow bench to briefly store clean objects in
Package clean objects ASAP
Do not cough or sneeze above (clean) objects
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Contamination control: Cleaning
1. Strategy: Step by step cleaning
Preclean
Removes film, visible dirt, gross contamination
Can be manual, industrial dish washer is preferred
Particle removal
Removes particles and droplets to required level
Often involves wet cleaning, ultrasonic
Rinsing is critical.
Molecular cleaningRemoves last molecules,
Drives off absorbed contaminants
Preferably done shortly before use
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Contamination control: Cleaning
1. Strategy: Cleaning strategy per material
Metals can tolerate most cleaning methods
Alkaline detergents can etch or stain aluminium
Glasses are vulnerable for micro-cracking caused by
ultrasonic agitation or etching by surfactants
Plastics are sensitive to solvents and might change
their properties (tacky surface or swelling)
Ceramics are often porous and can contain large
amounts of water: baking after cleaning necessary!
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Contamination control: Cleaning
2. Cleaning methods: precleaning
to remove visible dirt and oily residues, prevent clogging
Wiping
+ standard, no investment; - no control, labour intensive
Solvent and vapour degreasing
+ good for high volume - environment, k€
Industrial dish washer
+ well controlled - (k€)
Ultrasonics
+ standard, well controlled - k€, needs supervision
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Contamination control: Cleaning
2. Cleaning methods: particle removal
to remove all particles larger than a specified size
Ultrasonics usually good
New methods for submicrometer particlesMegasonics; CO2-snow; Nano-spray
1,0E-10
1,0E-09
1,0E-08
1,0E-07
1,0E-06
1,0E-05
1,0E-04
0,01 0,1 1 10 100 1000
Particle diameter [micrometer]
Forc
e [N
] capillary
VanderWaals
electrostatic gravity
Small = hard to remove
Binding force is smaller BUT• Removal force = even smaller
• Particles hide in roughness
• Boundary layer
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Contamination control: Cleaning
3. Cleaning methods: molecular cleaning
To remove molecules to specified outgassing rate or coverage
Baking in/of vacuum system + standard, proven; - high T, low P
Plasma+ relatively cool; quick - low P, crevices
Solvent and vapour degreasing+ good for high volume - environment, k€
UV-ozon (optical components)+ low T, 1 bar, quick - line of sight, O3
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Contamination control: Cleaning
4. After cleaning: packaging
Package a part as soon as is has reached room temperature
Always check if components are clean
Pack the objects in a clean bench or a flow bench
Touch the clean objects only with clean, non-powdered gloves
Seal the package and mark it with ‘clean parts’.
Package in layers
Aluminium foil (clean, getter, but may smear)
Plastic bags (clean, easy, may outgas)
Casing or box for physical protection during shipping
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Contamination control: Inspection
1. Pragmatic monitoring methods: non contact
Direct inspection
Compare to clean surface
Use strong and stable lighting and a binocular
Also inspect at grazing incidence
Black light (purpose built UV-source)
Will show up fluorescent contaminants
Use protective glasses, aim at surface only
Darken the room
Fluorescence
Will show up fluorescent contaminants, e.g. oils
Need to scan the surface
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Contamination control: Inspection
2. Pragmatic monitoring methods: contacting methods for particles
Wiping (white glove, white towel)
Wipe form clean to dirty
Compare to non-used glove or towel
Use strong and stable lighting, fiber optics
Tape test
Press transparent tape on object
Carefully remove and place on white paper
Compare tape to white paper
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Contamination control: Inspection
3. Pragmatic monitoring methods: contacting methods for greasiness
Water break test (ASTM Method F 22-26)Observes hydrophobic contaminants only
Breathing or atomizing is better alternative
Use contact angle measurements for qualification
Atomizer testGently spray deionized water over the surface
Observe whether droplets are deposited uniformly
Non-uniform spots due to hydrophobic contaminants
Contact angle measurementsSessile drop technique is preferred. Use DI-water
Semi-automized equipment is available (10-20 k€)
Sensitive to less than monolayer contamination
Water drop testPlace drop of 0.2 ml DI-water on surface.
Determine surface area (diameter) after standard time
Smaller = more hydrophobic = dirtier
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Contamination control: Inspection
4. Strategy for qualification of parts and assemblies
1. Set clear requirements with clientType of contaminant (gross, particle, grease, …)
Method for measurement (suitable for type of contaminant)
Maximum acceptable value (that can be determined by that method)
2. Develop clean production method (= handling, cleaning, packaging) Test with selected method
Optimize production process; document this
Train and coach the staff (this is an ongoing activity)
3. Ensure clean supply lineQualify your suppliers on quality control,
validated procedures, staff training and
coaching, supply chain, facilities
4. Perform regular tests All assemblies
functional test
All pieces
practical test
Critical
Random sampling
functional test
Random sampling
practical test
Non-
critical
AssembliesParts
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Conclusion