Contamination Control IN and OUT of the Cleanroom

BARBARA KANEGSBERG AND ED KANEGSBERG

Keeping Product Clean In and Out of theCleanroom, Part 1: The Interface

With Kevina O’Donoghue

30 � February 2009 Controlled Environments � www.cemag.us

Are you aware that incorrect materials transfer couldpose one of the biggest potential sources of contamina-tion within a cleanroom? How many of you can say thatwhile performing the transfer of materials into thecleanroom environment you are fully aware of youractions, practices, and methods?

KEEP THE PRODUCT CLEANPaperwork, raw materials for manufacturing the prod-uct, tools, and equipment must be successfullytransferred to the cleanroom. The goal of a materialstransfer program is to keep contamination from the out-side world from entering the cleanroom. Benefits ofinvesting effort in a materials transfer program includehigher quality product, lower costs, and an enhancedcompetitive position.

Some materials are double bagged, some singlebagged, and may be stored for long periods of time incardboard boxes in warehouse environments. Othermaterials such as tools may not be bagged at all andare likely to have come from an uncontrolled environ-ment.

Contamination control protocols for material transferare vital. Materials brought into the cleanroom that havenot been cleaned effectively during the transfer process

are an immense source of particulate and thin film con-tamination. Inadequately cleaned materials can be ahuge source of spore forming bacteria, extremely resist-ant bugs that are very difficult to eradicate from acleanroom environment. Manufacturers of all criticalproduct should be concerned about the impact of bio-logical contamination, not just those producing medicaldevices and pharmaceuticals. Many people are notaware that biological contamination will dramaticallyaffect particulate counts which are required in everycleanroom industry. At the same time, sterility is notenough; “dead dirt” can wreck havoc with criticaldevices. Water soluble lubricants and near-neutral pHprocesses can provide water, warmth, and nutrients, afavourable environment for biological contamination.

ROOM DESIGNMaterials transfer may be through a hatch leading directlyfrom an unmonitored manufacturing area to a clean-room or a transfer hatch between two cleanrooms. Isthis an optimal arrangement for your process? With ahatch, employees are tempted to stand on either side,engaging in lively conversation, even enjoying theirmorning coffee. Such behaviour increases the likelihoodof contamination. For new construction, consider amaterial transfer room.

Material transfer rooms should function like gowningrooms with a ‘clean’ side and a ‘dirty’ side. Very often aline of tape separates these areas. In practice, a “line inthe sand,” does not keep personnel from crossing overto the ‘clean’ side inadequately gowned or in streetclothes. Too often we see issues with high levels ofcontamination on the ‘clean’ side of the material trans-fer room where the root cause is the ‘dirty’ side.

Rather than a strip of tape, consider an “étagère,” aphysical barrier such as racking or cabinets that allowsexpedited transfer of materials while discouraging per-sonnel movement to the clean side. If racking or

Continued on page 29

Figure 1. Whenutilized properly,a hatch is oneoption for materi-als transfer. (Photo courtesy ofSealed Air Nelipak®,Galway, Ireland)

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Controlled Environments � www.cemag.us February 2009 � 29

SOIL IDENTIFICATIONPerhaps the main value of the device which is theembodiment of this suggestion is identification ofsoil components. It is that which eNoses most oftensupply computerized identification or recognition ofspecific aroma components. One can imagine useof a secondary computer algorithm to select theappropriate cleaning fluid based on analysis of soilcomponents and a database of HSP values.

NO CONTACT, NO FOUL!This device for recognition of surface contaminationdoesn’t have to contact the surface. Further theresponse time of the current generation of eNoses isaround one or so minutes. So the device could pro-vide on-line output that would be time-sensitive andindependent of surface roughness.

SUMMARYENoses are not expensive and not used in cleaningoperations at any level of surface soil content. Myquestion, why not? Critical cleaning, any cleaning,requires knowledge of chemical content and that’swhat an eNose provides.

Note: A patent application has been filed for thedevice when used to detect surface cleanliness.

Reference

1. Image courtesy of NASA’s JPL.

John Durkee is the author of the book Management of Industrial

Cleaning Technology and Processes, published by Elsevier (ISBN 0-

0804-48887). He is the author of the forthcoming book Solvent

Cleaning for the 21st Century, also to be published by Elsevier,

and is an independent consultant specializing in critical clean-

ing. You can contact him at PO Box 847, Hunt, TX 78024 or 122

Ridge Road West, Hunt, TX 78024; 830-238-7610; Fax 612-677-

3170; or jdurkee@precisioncleaning.com.

In and Out of the Cleanroom - Continued from page 30

cabinets are on wheels, it is simple to move them toallow access of large equipment or bulky materials. Ofcourse, because such barriers are not physically distinctrooms, the dirty side of the transfer room should alsobe fairly clean.

CONVENIENCECleaning materials within the transfer area must be con-venient. A wipe down station should always be visiblein the material transfer room with a low-residue clean-ing agent such as isopropyl alcohol (IPA) and low-lintwipes readily accessible. If there is a hatch rather than aroom, consider wipe down stations immediately beforeand immediately after transfer. If no wipe down stationis present, there is the temptation for personnel to passmaterial in without cleaning it.

TRANSFER VERSUS GOWNINGThe changing/gowning areas should not be used forwiping down and transferring materials to avoid poten-tial contamination of personnel and cleanroom clothing.Good practice within a cleanroom should generallyallow clean materials to come in one way and usedmaterials to exit by another area.

STAY TUNEDIn Part 2, we will discuss techniques for cleaning duringtransfer, managing bulky materials, and automation.

Barbara Kanegsberg and Ed Kanegsberg, “the Cleaning Lady and

the Rocket Scientist,” are independent consultants in critical and pre-

cision cleaning, surface preparation, and contamination control.

They are the editors of The Handbook for Critical Cleaning, CRC

Press. Contact them at BFK Solutions LLC., 310-459-3614;

info@bfksolutions.com; www.bfksolutions.com.

C O M P A N Y P A G E C O M P A N Y P A G E

Berkshire Corporation ...................................................32

BFK Solutions, LLC ........................................................27

Clean Air Solutions.......................................................27

Cleanroom Consulting ..................................................27

Crest Ultrasonics Corp ..................................................27

ESTECH ........................................................................7

Grieve Corporation ......................................................19

HACH Ultra Analytics ...................................................11

INTERPHEX..................................................................31

ITW Texwipe..................................................................5

KNF CleanRoom Products, Corp.......................................6

Park Bioservices, LLC ....................................................20

Pegasus Cleanroom Services .........................................27

Plascore, Inc. ...............................................................27

S-Curve Technologies ....................................................27

SEMICON China ...........................................................8

TSI, Inc..........................................................................2

Ultratape Industries, Inc. ................................................27

Veltek Associates, Inc. ...............................................3, 27

ADVERT ISER INDEX

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