Inspection technology for quality control after cleaning and
activationCleanliness in Control – Filmic Contamination| André
Lohse Online Seminar | 1
André Lohse, Head of Applications
SITA Messtechnik GmbH www.sita-process.com | www.sita-lab.com
Cleanliness in Control: Filmic Contamination
Cleanliness in Control – Filmic Contamination| André Lohse Online
Seminar | 2
Process Chain – The Source of Filmic Contamination
Starting Point:
Use of oils, grease, coolants, separation agent is essential for
machining and casting processes
Processes like bonding, coating, welding, … require clean
surfaces
Consequence:
Contaminations like oil, grease, coolants, separating agents, …
have to be removed in the cleaning process
The surface has to be clean enough for the specific gluing,
welding, … process (requirement/tolerance)
machining coating bonding welding
Cleanliness in Control – Filmic Contamination| André Lohse Online
Seminar | 3
Cleanliness is Crucial – Impact of Filmic Contamination
Pores in the weld seam
Further examples Soft spot formation in gas nitriding processes
Defects in coating (electroplating, PVD, CVD) Bad electrical
contact when soldering or bonding
Example Image Source: www.loctite.de
Example Image Source: wwww.besserlackieren.de
Example Image Source: ww.profabricationtechniques.com
Cleanliness in Control – Filmic Contamination| André Lohse Online
Seminar | 4
Task of Cleanliness Inspection
Aim: Check the cleanliness before painting to ensure good quality
and avoid discarding or reworking parts
Clean enough for painting?
Cleanliness in Control – Filmic Contamination| André Lohse Online
Seminar | 5
Common Techniques for Cleanliness Inspection
For Process Control Visual inspection Wipe test Water break test
Dyne test inks Contact angle measurement Fluorescence
measurement
For (Failure) Analysis in Laboratory Extraction/gravimetry of
non-volatile residues (NVR) Total organic carbon (TOC) IR
spectroscopy (FT-IR) Electron microscopy/X-ray spectroscopy
(SEM/EDX) X-ray photoelectron spectroscopy (XPS) Gas chromatography
with mass spectrometry (GC-MS) Residual gas analysis (RGA) Time of
flight – Secondary ion mass spectrometry (ToF-SIMS)
Guideline „Filmic Contamination in Control“ (see appendix)
Cleanliness in Control – Filmic Contamination| André Lohse Online
Seminar | 6
Measure Contact Angle – Test Wetting Behaviour
Wettability is sensitive to changes in surface condition Wetting
inhibiting and promoting substances, Oxidation and adsorption
layers, Chemical or physical activation/passivation SITA
SurfaSpector Mobile water contact angle measurement to check
wettability Patented method – easy handling on complex geometries
Allows quality inspection directly in production
environment Calibration standards for device verification Use for:
Cleanliness Inspection Surface Treatment Monitoring
Liquid
Surface
Cleanliness in Control – Filmic Contamination| André Lohse Online
Seminar | 7
Application: Analysis and Process Control in Electronics
Manufacturing
Application:
Starting point:
Solution:
1. Laboratory analysis XPS: residues of fluoropolymer interfere
with coating adhesion
2. Removal of fluorine residues by plasma cleaning
3. Contact angle measurement for process control of plasma
cleaning
Example Image Source: Plasmatreat
Example Image Source: www.ilh.uni-stuttgart.de
Cleanliness in Control – Filmic Contamination| André Lohse Online
Seminar | 8
Measure Fluorescence – Inspect Cleanliness
Fluorescence signal increases with film thickness/contamination
quantity
The lower the reading in RFU, the cleaner the surface
Standardised with SITA calibration standards
Contact free, non-destructive, in-line capable, thickness
sensitive
Use for:
Value in unit RFU (Relative Fluorescence Unit)
Contamination
Cleanliness in Control – Filmic Contamination| André Lohse Online
Seminar | 9
Example Applications
Sealing of Aluminium Housings Laser Beam Welding of Gears
Parts
Cleanliness in Control – Filmic Contamination| André Lohse Online
Seminar | 10
Application: Bonding of Gas Meter Housings
Application: Starting point: Solution:
Bonding of gas meter housings, optimisation of cleaning process
Limit value gas tightness of the bond increased, consequence: 58 %
rejects Optimisation of cleaning process, monitoring effect with
fluorescence measurement After optimisation: 0.1 % Rejects
Cleanliness in Control – Filmic Contamination| André Lohse Online
Seminar | 11
Application: Process Design and Optimization
Benchmark wet-chemical cleaning processes Laser
cleaning/stripping
CO2 snow blast cleaning Plasma cleaning
uncleaned cleaning machine
Example Image Source: Trumpf Laser Application Center
Cleanliness in Control – Filmic Contamination| André Lohse Online
Seminar | 12
Application: Coating Thickness Inspection of Anti-Corrosion
Oil
Application:
Starting point:
Solution: Inspection using fluorescence measurement
(quantity, even distribution)
Cleanliness in Control – Filmic Contamination| André Lohse Online
Seminar | 13
Further Information
„Filmic Contamination in Control“ Publisher: German professional
association of industrial parts cleaning (FIT – Fachverband
industrielle Teilereinigung) Target group: Users of measurement and
testing technology, process chain managers and plant
operators
Download: 2019_10_JOT_Optimised_inspection_technology_for_quality
_control_after_cleaning_and_activation.pdf
https://www.youtube.com/watch?v=LDuXGDaG8QQ
https://www.fit-online.org/publikationen/richtlinien
2019_JOT_Special_Defining_limit_values_for_sufficient_part
s_cleanliness.pdf
https://www.youtube.com/watch?v=W0HO51ZBUPM
SITA CleanoSpector
SITA SurfaSpector
Solutions for Quality-assuring Process Control
Measure Concentration.
Monitor Contamination.
Task of Cleanliness Inspection
Measure Contact Angle – Test Wetting Behaviour
Application: Analysis and Process Control in Electronics
Manufacturing
Measure Fluorescence – Inspect Cleanliness
Application: Process Design and Optimization
Application: Coating Thickness Inspection of Anti-Corrosion
Oil
Further Information