Effective Contamination Control Cleanroom Protocols Lab (-54)

1、Effective Contamination Control, Cleanroom Protocols, & Lab SafetyPresentation to LCI Cleanroom Users, 330-672-1583, 330-672-1525#G-003cExternal Resources*Cleanroom Technology: Fundamentals of Design, Testing, & Operation, W. Whyte, Wiley & Sons, 2001, ISBN 0 471 86842 6*Introduction to Contaminatio

2、n Control & Cleanroom Technology, Matts Ramstorp, Wiley-VCH, 2000, ISBN 3-527-30142-9Encyclopedia of Cleanrooms, Bio-Cleanrooms, and Aseptic Areas, Philip Austin, CRC Press, 2000, ISBN 0970113501Cleanroom Microbiology for the Non-microbiologist, David Carlberg, 1995, CRC Press, ISBN 0935184732 (2nd

3、edition due Oct 2004)Cleanroom Design, W. Whyte, Wiley & Sons, 1999, ISBN 0471942049Trade Publications:Cleanrooms Magazine, A2C2 Magazine, *=source for many of images in presentationOutlineIntroductionCleanroom definitionsFacility design & layout principlesAir flowContamination & MeasurementCleaning

4、 & Materials SelectionThe user!Protocols to improve controlSafety PracticesConclusionsThings to RememberIt is important for users to understand concepts behind clean processingBenefit from the experiences of others (standards, anecdotal information)Impact that a single user can have on overall proce

5、ss yield can be huge!Historical PerspectiveWhy Cleanrooms?First cleanrooms were in hospitals to prevent disease transmission and infection in operating rooms (over 100 years ago!)Valuable tool to prevent particulate and bio contaminationMost well known use is in semiconductor industry, but also esse

6、ntial in pharmaceuticals, flat panel displays, space program, photonics, life sciences, industrial (painting, assembly), etc.Essential for LCDs because of coating processes, small cell gapsCleanroom itself is only part of the solutionMethods to Achieve CleanlinessPositive Pressure / AirflowKeeps con

7、tamination out of the work areaDepends on clean air inputFiltrationDevelopment of effective filtration revolutionized industryHEPA (High Efficiency Particulate Air) and ULPA (Ultra Low Particulate Air) Filters Materials SelectionUser ProtocolsCleaningAll are very important!Definition of Clean Room /

8、 Area IIn US, classes still referred to as defined by Federal Standard 209DDefinition of Clean Room / Area IINow superseded by ISO 14644-1; particles measured per cubic meterDefinition of Clean Room / Area IIIConversion between standards:Outline revisitedIntroductionCleanroom definitionsFacility des

9、ign & layout principlesAir flowContaminationMeasurementThe user!Protocols to improve controlFacility DesignComplete cleanroom created with centralized air handling or fan filter unitsKeeps entire room cleanRequires complete gowning, careful materials and equipment selection to maintain classCostly,

10、often unnecessaryFacility DesignCan use localized clean areasClean Benches: Horizontal and Vertical Laminar Flow (HLF on left, VLF on right)Facility designIsolators, Glove boxes provide better protection from outside contaminationContamination Control by LayoutIsolation between processes prevents cr

11、oss contamination; separate rooms, air showers, door interlocks“Onion” concept: cleanest areas are inside, have to pass through successively cleaner areas to reach these areasOutlineIntroductionCleanroom definitionsFacility design & layout principlesAir flowContamination & MeasurementCleaning & Mate

12、rials SelectionThe user!Protocols to improve controlAir Flow & TurbulenceMost airflow is turbulentno clear relation between velocity vectors at different pointsNot optimal for contamination control! Long path length for contamination to leave the roomParticles can be trapped in eddies for long timeL

13、aminar (Unidirectional) Air FlowConcept of laminar airflowIn cleanrooms, often called uni-directional flow (UDF) Ideal for contamination controlshortest path to sweep particles out of clean areas; complete room air change in shortest period of timeHow is this applied in cleanrooms?High level cleanro

14、oms designed for laminar flow in most areasCost means that for most, clean areas are some combination of laminar and turbulent flowNot always a simple tradeoffwith turbulent flow, require higher air velocities, which require larger air handlers ($)UDF More Important for Cleaner AreasPractical Consid

15、erations for UDFAny objects in path of laminar flow will deflect airflowthis usually results in turbulence; USER BEHAVIOR HAS LARGE IMPACTMost critical for laminar flow benches situated in non-clean areas; not as critical if located in larger clean areaOutlineIntroductionCleanroom definitionsFacilit

16、y design & layout principlesAir flowContamination & MeasurementCleaning & Materials SelectionThe user!Protocols to improve controlTypes of ContaminationParticulateencompasses most contaminationChemicalfilms, vapors, etc.Biologicalbacteria, viruses, etc.; for our purposes, treat as particlesSimilar c

17、oncerns for rooms & equipment as for substratesAirborne ContaminationFrom Cleanrooms Magazine, 2000Invisible to naked eye below 50um without special illuminationParticulate ContaminationBiggest concern for LCI cleanroom usersBasis for classification of cleanroomsDoes include biological contamination

18、 as a subset of total particulatesMany sources: personnel, equipment, etc.Problem of AerosolsGeneric term for particles that tend to remain airborneSmall size of particles means that gravity has lesser effect; think cigarette smokeCan remain in turbulent eddy currents for long periods, not removed f

19、rom roomMicrobial ContaminationOuter layer of human skin can host up to 1 million microorganisms per square cmHuman saliva up to 1 billion per mLBacteria is usually primary concern, but foreign organic matter, viruses, fungi, algae are all included hereCross contamination can be a big issue!Contamin

20、ation MeasurementParticulate contamination typically measured with laser particle counterMicrobial contamination can be measured in several waysCentrifugal samplerSettle plate methodContact plate methodSwabbingHow to Use MeasurementsComplementary to yield trackingCan use measurements to isolate prob

21、lem areasRegular measurements can help to track changes, which can then be tied back to protocol, personnel, or material changesDont depend upon room to maintain itself; verify!Possible to isolate culture lines responsible?RealityIn a perfect world, could monitor many points on a very regular basisI

22、n reality, this is usually not practical, due to personnel time and financial constraintsImportant to identify a realistic test & measurement programOutlineIntroductionCleanroom definitionsFacility design & layout principlesAir flowContamination & MeasurementCleaning & Materials SelectionThe user!Pr

23、otocols to improve controlContamination Control and Its Relationships All sources of contamination and control are interrelated CleaningCritical to remove contaminants that cannot be removed by air handlingImportant to follow procedures appropriate to your applicationWhat is appropriate for one indu

24、stry may not be appropriate for anotherMost important thing is to develop standard procedures and FOLLOW THEMSurfaces are importantThe efficiency of these cleaning methods depends on the surface being cleanedRough or pitted surfaces are more difficult to cleanSharp corners are difficult to cleanWhy

25、are inside surfaces of cleanrooms smooth?VacuumingDry and wetDry has low (25% ) efficiency for particles smaller than 10 microns (about .0005 inches)wet uses liquids which result in greater force on the particles and hence better cleaningWet wipingCan be very efficientLiquid breaks some bonds betwee

26、n surface and particles and allows particles to float offThose adhering on surface can be rubbed off and retained in wiper.Must be careful not to redeposit particlesEfficiency variesTacky rollersEfficiency depends of tackiness of roller, cleanliness of tacky surface and softness of roller are also v

27、ery importantCleaning liquidsNo ideal cleaning liquidMost facilities use DI water or isopropyl alcohol with disinfectantWater with surfactant and disinfectant may be used as well as alcohol-water solutionsThe choice depends on what works, cost, history, etc.Materials SelectionChoice of materials for

28、 supplies, equipment, gowning, etc. is important“Clean” materials can become dirty!Look for easy-to-clean materialsTriboelectricity can cause static problems, as can low humiditythis exacerbates contamination problemsBiofilms!OutlineIntroductionCleanroom definitionsFacility design & layout principle

29、sAir flowContamination & MeasurementCleaning & Materials SelectionThe user!Protocols to improve controlConclusionsImpact of the Cleanroom UserTruth: Manufacturers can achieve similar yield results using cost effective flow hoods and isolation chambers as with full-blown central cleanroomsBUT: user b

30、ehavior is much more critical in these areas!Gowning at the LCI, IPut on plastic shoe covers (booties) over your shoes in the hallwayIf you wear boots or other heavy contaminating shoes, consider keeping a pair of sneakers in your office for use in the cleanroomOpen door and enter cleanroomLog in on

31、 computer at entrancePut on gowning glovesGowning at the LCI, IIPut on hairnetIf using Class 10K south only, put on lab smock and proceed to usage areaIf using main cleanroom, proceed to gowning roomPick up an appropriately sized head cover and put onIf previously in cleanroom, can use garment store

32、d on hangerGowning at the LCI, IIIPick up an appropriately sized coverall and put on, being careful to avoid allowing coverall to touch floorTuck head cover into coverall before zipping up coverallPick up an appropriately sized set of shoe covers and put on over plastic booties and coverall; snap sh

33、oe cover to back of pant leg and pull tightPut on second set of gloves, being careful to pull glove over cuff of coverallPut on safety glasses and proceed to air showerCommon Protocol Violations Not wearing Safety GlassesImproper gowning zippers, snaps, masksNon-cleanroom materials in cleanroompaper

34、, cardboard, personnel itemsNot cleaning up after you are finishedGeneral conductFast motions, incorrect carrying of materialsRemember laminar flow; minimize turbulenceEffect of the Cleanroom UserActivity and Particle GenerationUser behavior has huge effect on particle generation (from Ramstorp)Gene

35、ral Cleanroom User Requirements IMinimize sources of contaminantsNo smokingNo cosmeticsAvoid high particulate clothing, such as wool sweatersCover up! Uncovered skin can lead to more contaminationActivity and Contamination (from Ramstorp)Protocols to Improve Contamination ControlFollow gowning procedures and restrict materials used in cleanroomAn educated worker is essential to proper job performance; workers should be well versed in the how and why of their jobYou as the User IVery important to think about each and every action you take:How does this affect cleanli