Product Spotlight
08/01/2002
Swabs and wipers: Two critical consumables
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Process engineers are now being charged witht he task of controlling contamination control's most daunting menace.
by Mark A. DeSorbo
Swabs and wipers are two consumables that are crucial for both critical and non-critical cleaning processes.
For the disk drive industry, the swab and wiper combat electrostatic discharge (ESD) and perpetrating particles that can render a unit useless on contact. Pharmaceutical manufacturers, as well as manufacturers in other industries holding federal current good manufacturing practices (cGMPs) near and dear, rely heavily on these consumables to ensure sterility, which is a must when it comes to validating the process.
In an article penned for CleanRooms in 1997, two experts on consumables shared their clairvoyance.
"Ever-increasing miniaturization requirements throughout the electronics industry are at the same time leading to new requirements for cleaning," said Dr. Mo Tazi, director of research and development for Coventry Clean Room Products (Kennesaw, GA). Likewise, Jack McBride, president of Contec Inc. (Spartanburg, SC), pointed out that, "while the products themselves will not change drastically, the scale against which they are measured will." [See "The do's and don'ts of cleanroom wipes and swabs," as well as other articles on cleanroom consumables at www.cleanrooms.com.]
Swab story
Swabs are perhaps the less sophisticated of the two consumables, although serving several functions from applying materials meticulously, keeping contamination at bay and reducing defects for devices like ESD-sensitive disk drives.
While swabs can be application matched, many can also be modified to meet specific user needs. Variables include handle material, tip size, head materials and solvent-retention capability.
A variety of swab head materials and styles can be had, including wrapped foam, sealed foam, wrapped polyester, sealed polyester and foam over cotton. Folding the head material around the handle is how most wrapped swabs are made, and this type is particularly useful for precision cleaning critical surfaces. Others employing the head-to-handle manufacturing process use no adhesives or binders that could contaminate the application.
Among the handle materials offered are polypropylene, nylon, glass-filled nylon, wood and styrene. Many suppliers address the issue of static contamination by offering both conductive and static-dissipative swab handles.
Not so whimsical about wipers
What makes wipers stand out from swabs is perhaps the science behind the actual making of the consumable.
The Texwipe Co. (Upper Saddle River, NJ), now owned by Illinois Tool Works (ITW), has its proprietary Vectra process, which is completely automated and uses minienvironments to produce ultra-clean wipers in successive steps.
At times, competition comes down to price, while other times it all comes down to the features of a given wiper, which range from lint-free, sealed-edges, low bio-burden levels, shape and texture, woven and non-woven, dry and pre-saturated and absorptive and adsorptive.
The wiper is not only popular among industries employing contamination control, but in the consumer markets as well. There are wipers to clean the home, the automobile and even special personal ones for quick cleansing of the face, neck, chest and arms.
For companies like AdvantaPure, a Southampton, PA-based maker of silicon hose and tubing for a host of industries that use cleanrooms, "the cheaper the wiper, the better," says Don Warner, director of marketing.
"[Cleanroom personnel] shop around, and whatever is the cheapest brand, they buy it, as long as it is lint-free," he says, adding that there is no special brand. "They dampen them with isopropyl alcohol and wipe the machines down once a shift. The wipers are also fitted to mops and the floors are mopped, too."
As far as the industry goes, nothing really new in the way of a wiper has been introduced, says Claudio Orefice, president of High-Tech Conversions, Inc. (Enfield, CT). "Everybody is looking for something different, and there is no one wipe that does it all," he says. "If you can make one, you'd be a billionaire."
High-Tech, however, just unveiled Nova-Tech 1000, a gamma-sterilized wiper for general cleaning in ISO Class 6 settings or cleaner that is made of a blend of virgin polyester and cellulose that is hydro-entangled for strength and absorbency.
Many consumables manufacturers, including High-Tech, have come out with new dispensers to replace "pull-out" canisters and re-sealable pouches. Often times, wipers are scuffed through the hole of the top of the canister, loosening fibers and releasing a source of contamination.
"With the re-sealable pouches, the wiper always runs the adhesive label on the way out, contaminating the wiper," Orefice says. "After awhile, it won't stick anymore and the wipers will dry up or become contaminated."
Now, containers like those that hold High-Tech's FreeSAT wipers, can be opened and closed with one hand, letting you hold the item to be cleaned with the other hand and erasing the possibility of introducing contaminating fibers.
When it comes to wipers, however, Orefice compares them to drugs at a pharmacy. "Whatever ails you," he adds, "you can find a wiper to remedy it."