CONTAMINATION CONTROL

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

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

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

Requirements • Inorganic / Particulate contamination • Airborne • ISO-14644-1 (1999) – superseded FED-Std-209) “ Cleanrooms and associated controlled environments” • PSS-01-201 / ECSS Q-70-01 - “Cleanliness and Contamination control” • Surface contamination • IEST-Std-CC1246D - “Product Cleanliness levels and Contamination control program” superseded Mil-Std-1246C • PSS-01-201 / ECSS Q-70-01 Materials and Processes Division ESA-ESTEC TOS/QM

Requirements Materials and Processes Division ESA-ESTEC TOS/QM

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

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

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

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

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

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

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

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

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

VBQC Materials and Processes Division ESA-ESTEC TOS/QM

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

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

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 • Contamination control plan • Preventive • All requirements are mentioned • Procedures for delicate handling or testing Materials and Processes Division ESA-ESTEC TOS/QM

CONTAMINATION CONTROL