Clean production in an industrial environment

Clean production
in an industrial environment

Anton de Jong, Anton Duisterwinkel

1
2011-03-11
Themadag Schoon Produceren

CONTENTS

1. Introduction
2. Systematic approach of assessing risks
3. Contamination control
- Prevention
- Cleaning
- Detection and Qualification

2
2011-03-11

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

3
2011-03-11

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

4
2011-03-11

Contaminants: what and where from?

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)

Object surface

5
2011-03-11

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 !

6
2011-03-11

What is clean?

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

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2011-03-11

CONTENTS

1. Introduction
- Prevention
- Cleaning

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2011-03-11

Systematic approach for contamination control:
Example:

1. Products and production scheme
Supplier: D Supplier: B
T = .. T = ..
Product : example complex assy
002 002
lfeedthrough Gas hoses Supplier: A
s
T = ..

001 003 t=.. 004, t=.. t=.. 005 t=.. 004, t=.. t=.. 005 t=.. 008 t=..
002 Milling Intermediate Transport to Melt in
Material for QD1: Intermediate Transport to Weld gas Intermediate
fQ Louwers
backplate Mat. Cer. Wet clean electrical Wet clean A hoses to Wet clean
Supplier: A feedthroughs backplate
T = ..
001 003 t=.. 004, t=.. 007 t=..
Material for 002 Milling Intermediate Store
QD1:
cooler body fQ Wet clean
Mat. Cer. 028 t=.. 008 t=.. t=..
Weld water 002 Intermediate Transport to
hoses to Press Wet clean T
Supplier: B 023 026, t=.. 027 t=..
024 cooler body
Water Hose QD1: Intermediate Store
T = .. fQ
Mat. Cer. Wet clean

029
041 032, t=..
044, t=.. 033 t=..
Filament
Vac. Bolts QD1:
030
042
QD1: Intermediate
Intermediate Store
fQ
fQMat. Cer. Wet clean
Mat. Cer. Wet clean
Supplier: C
T = ..
035 038, t=.. 039 t=..
Screws 036
QD1: Intermediate Store
fQ Wet clean
Mat. Cer.

2. Assessment of the risks (FMEA)

3. Solving of the most important risks

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2011-03-11

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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2011-03-11

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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2011-03-11

Strategy for the control of a production process
Example:
Supplier: D Supplier: B
T = .. T = ..
Product : example complex assy
002 002
lfeedthrough Gas hoses Supplier: A
s
T = ..

001 003 t=.. 004, t=.. t=.. 005 t=.. 004, t=.. t=.. 005 t=.. 008 t=..
Material for 002 Milling Intermediate Transport to Melt in
QD1: Intermediate Transport to Weld gas Intermediate
fQ B
Louwers
backplate Mat. Cer. Wet clean electrical Wet clean A hoses to Wet clean
Supplier: A feedthroughs backplate
T = ..
001 003 t=.. 004, t=.. 007 t=..
Material for 002 Milling Intermediate Store
QD1:
cooler body fQ Wet clean
Mat. Cer. 028 t=.. 008 t=.. t=..
Weld water 002 Intermediate Transport to
hoses to Press Wet clean T
Supplier: B 023 026, t=.. 027 t=..
024 cooler body
Water Hose QD1: Intermediate Store
T = .. fQ Wet clean
Mat. Cer.

029
041 032, t=..
044, t=.. 033 t=..
Filament
Vac. Bolts QD1:
030
042
QD1: Intermediate
Intermediate Store
fQ
fQMat. Cer. Wet clean
Mat. Cer. Wet clean
Supplier: C
T = ..
035 038, t=.. 039 t=..
Screws 036
QD1: Intermediate Store
fQ Wet clean
Mat. Cer.

• Choice and sequence of the production steps
• Detail for the production steps

12
2011-03-11

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)

13
2011-03-11

FMEA (2)

FMEA score Ernst Voorkomen Detectie
1 1 geen nooit zeker
minimale gevolgen voor product zeer
2 (alleen kritische klanten) vrijwel nooit waarschijnlijk
2 minimale gevolgen voor product
3 (50 % van klanten) laag waarschijnlijk
4 gemiddelde gevolgen voor product af en toe boven gemiddeld
3 met
5 grote gevolgen voor product tussenposen gemiddeld
kleine schade aan
6 productieapparatuur regelmatig laag
7 4 schade aan productieapparatuur erg regelmatig erg laag
grote schade aan
8 productieapparatuur vaak onwaarschijnlijk
5 zeer
9 wettelijke normen erg vaak onwaarschijnlijk
10 mensveiligheid extreem vaak niet mogelijk

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2011-03-11

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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2011-03-11

CONTENTS

1. Introduction
- Prevention
- Cleaning

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2011-03-11

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

17
2011-03-11

Contamination control: Prevention

1. Design rules

Source control
Clean 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 conditions
Add chemicals that remove dirt; prevent hot spots

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2011-03-11


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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2011-03-11


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’

20
2011-03-11


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

21
2011-03-11


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

22
2011-03-11

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 cleaning
Removes last molecules,
Drives off absorbed contaminants
Preferably done shortly before use

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2011-03-11


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!

24
2011-03-11


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

25
2011-03-11


2. Cleaning methods: particle removal
to remove all particles larger than a specified size
Ultrasonics usually good
New methods for submicrometer particles
Megasonics; CO2-snow; Nano-spray

1,0E-04

1,0E-05 Small = hard to remove
1,0E-06
capillary Binding force is smaller BUT
Force [N]

1,0E-07
• Removal force = even smaller
VanderWaals
1,0E-08
• Particles hide in roughness
1,0E-09
electrostatic gravity • Boundary layer
1,0E-10
0,01 0,1 1 10 100 1000
Particle diameter [micrometer]

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2011-03-11


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

27
2011-03-11


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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2011-03-11

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

29
2011-03-11


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

30
2011-03-11


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 test
Gently spray deionized water over the surface
Observe whether droplets are deposited uniformly
Non-uniform spots due to hydrophobic contaminants
Contact angle measurements
Sessile drop technique is preferred. Use DI-water
Semi-automized equipment is available (10-20 k€)
Sensitive to less than monolayer contamination
Water drop test
Place drop of 0.2 ml DI-water on surface.
Determine surface area (diameter) after standard time
Smaller = more hydrophobic = dirtier

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2011-03-11


4. Strategy for qualification of parts and assemblies

1. Set clear requirements with client
Type 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 line Parts Assemblies
Qualify your suppliers on quality control, Non- Random sampling Random sampling
validated procedures, staff training and critical practical test functional test
coaching, supply chain, facilities
Critical All pieces All assemblies
4. Perform regular tests practical test functional test

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2011-03-11

Conclusion

Clean production in an industrial environment

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