CONTAMINATION CONTROL SME-Course D : Materials Materials and Processes Division Materials Physics and Chemistry Section Jaco M. Guyt TOS-QMC Topics 1 Types of contamination 2 Cleaning procedures 3 Prevention Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Introduction Why contamination control ? Satellites are operational in orbit - no maintenance after launch Sophisticated equipment with higher demands on performance Increased mission duration Increased reliability is needed Materials and Processes Division ESA-ESTEC TOS/QM

Part 1 Types of contamination Introduction Origin of Contaminants Requirements Verification of requirements Handling of contamination problems Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Introduction Definition Any foreign matter Unwanted deposition on surfaces. Contamination effects On thermal control surfaces - changes  and  ratios On solar arrays - decrease on power output On optical instruments - decrease signal / scattering In waveguides - Multipaction Materials and Processes Division ESA-ESTEC TOS/QM

Types of contamination Organic and Inorganic contamination coming from Humans - Skin, handling greases/salts, hair, cosmetics Clothing - Fibres, dust collected in clothing Materials - Outgassing, solvent extraction, creeping(oil greases), direct contact, degradation Vacuum test - Pump oils, chamber history, turbulence at start, venting (lines and gas quality) Machining - Drilling, abrasion, polishing, cleaning Transport - Packaging, pressure drop in plane Space - Pyro-valves, wire cutters, thrusters Exposure C. R.- Working activities, soldering, air circulation Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Requirements Inorganic / Particulate contamination Airborne ISO-14644-1 (1999) – superseded FED-Std-209) “ Cleanrooms and associated controlled environments” PSS-01-201 / ECSS Q-70-01 - “Cleanliness and Contamination control” Surface contamination IEST-Std-CC1246D - “Product Cleanliness levels and Contamination control program” superseded Mil-Std-1246C PSS-01-201 / ECSS Q-70-01 Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Requirements Materials and Processes Division ESA-ESTEC TOS/QM

Requirements Fed-Std-209E Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Requirements ISO-14644_1 Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Requirements ISO-14644_1 Materials and Processes Division ESA-ESTEC TOS/QM

Requirements Mil-Std-1246C Materials and Processes Division ESA-ESTEC TOS/QM

Requirements Mil-Std-1246C Materials and Processes Division ESA-ESTEC TOS/QM

Requirements Mil-Std-1246C Materials and Processes Division ESA-ESTEC TOS/QM

Requirements IEST-STD-CC1246D Materials and Processes Division ESA-ESTEC TOS/QM

Requirements IEST-STD-CC1246D Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Requirements Organic Contamination PSS-01-201 / ECSS Q-70-01 exposure in clean room during a continuous period of one week, less than 2.0x10-7 g/cm2 Exposure in vacuum chamber after a blank test of 24 hours, less than 1.0x10-7 g/cm2 Project depending, more stringent levels. ECSS Q-70-02A Outgassing requirements of materials. IEST-Std-CC1246D Level AA5 up to level J, what is 10 ng till 25 mg per 0.1m2 Materials and Processes Division ESA-ESTEC TOS/QM

Requirements Mil-Std-1246C Materials and Processes Division ESA-ESTEC TOS/QM

Requirements IEST-STD-CC1246D Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements Organic Contamination Visual inspection - levels unto 10-6 g/cm2 range ECSS-Q-70-02 (old PSS-01-702) “Thermal vacuum outgassing test for the screening of space materials” PSS-01-705 (ECSS-Q-70-05) “The detection of organic contamination of surfaces by infrared spectroscopy” ASTM E1235 “Gravimetric Determination of Nonvolatile Residue (NVR) in Environmentally Controlled Areas for Spacecraft” ESTEC work instructions : contact and immersion test Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements Micro VCM Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements Micro VCM Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements Micro VCM Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements Acceptance limits PSS-01-702 : TML < 1.0%, CVCM < 0.1% Acceptance limits ECSS-Q-70-02A : RML < 1.0%, CVCM < 0.1% Micro VCM results TML RML CVCM WVR Remarks A - 1.12% 0.05% 0.01% 1.07% Too high water B - 0.56% 0.45% 0.23% 0.11% Too high CVCM C - 2.15% 1.01% 0.09% 1.14% Too high TML/RML D - 9.52% 9.50% 6.17% 0.02% Too high RML/CVCM Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements PSS-01-705 (ECSS-Q-70-05) “The detection of organic contamination of surfaces by infrared spectroscopy” Identification due to specific absorption of the molecule due to vibrations and rotations of atoms Quantification by Lambert/Beers Law relation Abs. = E * b * C E = Molar Absorption Coefficient b = Pathlength C = Concentration Calibration curves for four standards Paraffin, Di-octylPhthalate ester, Methylsilicone and MethylPhenylsilicone Abs. Absorption of sample Concentration of sample Concentration Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements Sampling for infrared analysis Indirect by rinsing surface with solvent and analyse of NVR Indirect by wiping surface with tissue and analyse of NVR Direct by using infrared transparent windows ZnSe, CaF2 Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements Particulate Contamination Airborne Counters - Fed Std 209E Surface contamination Visual inspection, less than 300 ppm ECSS-Q-70-50, Particle Fall Out measurement ASTM E1216, Tape lift method ASTM F312, Counting and sizing particles ASTM F311, Liquid samples Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements PFO - meter Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements Particulate Contamination PFO meter and correlation with cleanliness specifications table Materials and Processes Division ESA-ESTEC TOS/QM

Verification of requirements Tape lift method as performed at ESTEC Define area which needs to be checked Take Polyethylene transparent tape from 3M Scotch 480 Stick it on a surface of at least 5 x 5 cm Take with tweezers the 0.45 micron filter paper with grid Apply the filter paper against the just released tape Cut excessive tape away Count particles by Microscope in different size ranges Materials and Processes Division ESA-ESTEC TOS/QM

Handling of contamination problems Define problem and location Define starting point of problem Write Non Conformance Report (NCR) Identification of contamination by analysis Search for possible sources on location Detailed Material Lists Excluding by analysis / search / calculation Materials and Processes Division ESA-ESTEC TOS/QM

Handling of contamination problems Can the problem be solved? Can we live with it? Will it happen again? Can we avoid the risk by preventive actions or adjusting procedures? Materials and Processes Division ESA-ESTEC TOS/QM

Part 2 Cleaning Procedures Introduction Selection of Cleaning method Verification of cleaning efficiency Cleaning procedure Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Introduction Definition of clean A contamination level below the acceptance limits or not detectable with the used method. Procedure for cleaning is needed for Customer - that you are cleaning and how Personnel - that they know how to clean and what Sub-contractor - that they know how and what are the requirements Materials and Processes Division ESA-ESTEC TOS/QM

Selection of Cleaning method Selection should be based on : Method compatibility with hardware ultrasonic, temperature, mechanical scratching Method efficiency with hardware accessibility design Solvent compatibility with hardware corrosion, chemical attack, dissolving, removable Solvent efficiency for contaminant what are you removing, polar/non-polar Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Cleaning methods Mechanical cleaning - grinding, brushing, blasting Detergent cleaning or soap cleaning Solvent bath / ultrasonic Chemical cleaning - acids, alkalines and salts Vacuum bake out Vacuum cleaner / ionised air Plasma cleaning Dry ice Polymer film Adhesive Materials and Processes Division ESA-ESTEC TOS/QM

Verification of cleaning efficiency By representative test samples and checked visually or by analysis Visual inspection after cleaning Check of hardware by taking samples, followed by analysis Check performance of hardware and verify against previous tests Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Cleaning procedure Should contain description or information about Hardware Method, with details about e.g. solvents/duration and flow chart Restrictions or hazards for hardware or personnel Requirements Verification of requirements Inspection after cleaning Operators (trained) Logbook entry Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Part 3 Prevention Introduction Material selection Garment Potential risks Preventive actions Contamination control plan Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Introduction Prevention is better and cheaper then the cure!! Think ahead. If you are not sure it will contaminate the hardware? Stop the activity! Because the answer is yes. If something can go wrong, it will go wrong. Working towards a dead-line is where prevention looses its power. Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Material selection Outgassing characteristics low TML and CVCM Mass of used material Location Optical applications Cryogenic High Temperature Long term predictions with VBQC Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division VBQC Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division VBQC Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division VBQC Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division VBQC Results taken out of the Mathematical treatment consist of Accelaration factor, Activation energy, Residence time - Temperature dependency. Long term predictions with VBQC data is used within the temperature range of test. The TML or CVCM data are fitted period by period with a sum of 6 exponential equations. With W0.i the variables, affected with the time constant 0,i, which are 50, 20, 5, 1, 0.5 and 0.1 hour. Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Garment As humans are the main source of contamination, garment should be taken into account from the beginning of the project. Depending of the contamination budget allocated to a specific operation, selection of garment can be done Storage of garment should be separate from street clothing Procedure of dressing should be trained to the personnel Regular cleaning of garment by specialised company / quality check Materials and Processes Division ESA-ESTEC TOS/QM

Materials and Processes Division Potential risks Potential risks Preventive actions Thermal vacuum tests Check procedure Pumping oils Blank test Outgassing of materials Check DML Solar radiation Adequate thermal protection Clean room operations Training of personnel Too many personnel in C.R. Entry form Unauthorised entry in C.R. Access code for CR / locked Maintenance in C.R. Check impact, protect items Violation of dress code Clear signs on doors,training Dirty activity during AIT Separate from sensitive item Materials and Processes Division ESA-ESTEC TOS/QM

CONTAMINATION CONTROL PLAN Preventive All requirements are mentioned Procedures for delicate handling or testing Materials and Processes Division ESA-ESTEC TOS/QM