Omur Sezerman, President, OZ Optics, provided the following testimonial letter regarding their experience with a CO2 composite spray cleaning system for cleaning electro-optical devices during manufacturing.

“I want to thank you for introducing the CO2 composite spray cleaning technology to OZ Optics, Limited (OZ Optics).  OZ Optics is a leading worldwide supplier of fiber optic products for existing and next-generation optical networks. In addition to designing and manufacturing components and test equipment for fiber optic markets, the company has also been very active in developing fiber optic sensors for remote monitoring of oil pipelines, wells, bridges, dams, airplanes, and other large structures.

We have determined that CO2 composite spray cleaning technology is very useful as an alternative to alcohol and manual wipe cleaning techniques to remove polishing residues, dust particles and fingerprints from our optical components during manufacturing and test operations.  We have successfully used this technology in combination with custom fixtures to develop proprietary cleaning processes for several of our commercial products.  These have included polished fiber optical surfaces, lenses and optomechanical assemblies.  CO2 composite spray cleaning is used to enhance light transmittance, increase power handling of high powered laser optics, prepare surfaces for optical coating, and to ensure long term stability and functionality of critical optical components.

The CO2 composite spray cleaning technology minimizes the use of organic cleaning solvents and other conventional optical cleaning products.  The technology eliminates smearing and re-deposition of cleaning residues and can clean a variety of fiber and lens geometries.  Our traditional optical device cleaning method uses an ultrasonic bath, which typically employs several steps including rinsing and drying.  With the new dry, non-contact CO2 composite spray cleaning process, precision cleaning time has been reduced from 10% to 40% depending upon the particular component cleaning application.

In closing, the CO2 composite spray cleaning technology has been a very positive addition to our optical device manufacturing line, providing superior cleaning performance, decreasing the cost of production, and contributing to a cleaner working environment.  We look forward to purchasing additional CO2 precision cleaning equipment from your organization.”

Omur Sezerman
OZ Optics
Ottawa, ON Canada

Letter to Cleanlogix LLC, July 31, 2009

DoverTech-Weldcraft manufactures welding equipment, which includes precision machining processes that produce contaminated subassemblies.

“Like many companies, we were faced with the challenge of replacing our conventional vapor degreaser,” stated Paul Lien of Dover Tech-Weldcraft Corporation (Burbank, CA).  “Initially we looked into water-based cleaning, thinking it was the obvious solution to our cleaning problems.  We tested several aqueous-base systems and found they did a good job.”

“There were three main concerns with aqueous cleaning systems.  The first concern was how to deal with the waste.  We operate in a city that demands strict adherence with the air and water municipality’s disposal guidelines.  The second concern was the increase in maintenance costs of both the water-based equipment and all the support equipment.  The third concern was bath life and bath maintenance.  We also realize that current wastewater disposal regulations are subject to change at any time.”

“We clean our parts in preparation for brazing and/or molding operations and, as such, cannot tolerate any residue/oil.  We require consistently clean parts all day, every day, without an on-board chemist checking pH and concentration of the aqueous solutions.  When we were introduced to a dry cleaning process that uses LCO2, Our initial thought was ‘Even if it worked, could we afford it?’  Well, as it turned out, we could not afford to not have it.”
Lien explained that his company first tested an LCO2 cleaning system four years ago.  “Our goal was to eliminate the use of pollution-generating cleaning processes,” he remarked.  “We found the LCO2 cleaning process to be more effective, extremely consistent, and less costly to operate than our TCA solvent process and the alternate aqueous systems we initially considered.

“Our analysis involved a detailed comparison of both capital equipment and ongoing operational costs of the various systems being considered.  Our analysis confirmed that although the LCO2 system was more capital-intensive than the water-based option, the operational cost difference between the two provided the necessary justification for the purchase of the LCO2 equipment.  The operational cost difference between the LCO2 and water-based process was significant at approximately $2500 per month.  After much testing and cost analysis, we purchased an LCO2 system for our production operation.

“Four years ago we implemented the technology and, after some initial startup glitches, we have run successfully ever since.  Our production demand requires us to clean medium-size brass and copper components 17 hours a day, 6 days a week.  Our monthly operational cost to run the LCO2 system is approximately $450.  To date, we have experienced no real down-time with the LCO2 system.  Our concerns regarding bath maintenance were resolved since the LCO2 process does not degrade over time.  And finally, we now generate no pollution related to cleaning processes and enjoy consistently clean product on a daily basis.”

“Liquid CO2 Immersion Cleaning: The User’s Point of View”, Parts Cleaning, April 1999

Gary Knoth, Senior Contamination Control Engineer, WDC, provided the following input for a technical paper published in the IEST Journal.

Advanced carbon dioxide (CO2) composite spray cleaning has been shown to be an effective alternative to traditional spray and immersion cleaning processes, as well as conventional snow cleaning, for selectively removing contaminants and films from partially assembled hard disk drive (HDD) components during the remanufacturing or rework process.  CO2 consumption is reduced significantly using a composite spray while spray cleaning control and performance is improved.  CO2 composite spray cleaning performance is dependant upon the position, speed and motions of the spray applicator, and are matched to comply with HDD factory output.  Stored spray cleaning programs deliver precise cleaning 7 days a week, 24 hours per day with uptimes exceeding 99.9% over a six month period.  Monitoring and controlling composite spray cleaning process parameters including spray pressure and composition, scanning speed, and pallet/part identification are all done automatically.  Operator interaction is limited to loading and unloading pallets for continuous system operation.

“Automated CO2 Composite Spray Cleaning System for HDD Rework Parts”, Journal of the IEST, V. 52, No. X, 2009

Bill Fisch of AccraTronics Seals Corporation, a contract machining company, found the LCO2 process to be a “perfect fit” for his company’s cleaning requirements.

“Our cleaning requirements are basic: clean enough for inspection and for further processing internally or at various vendors,” stated Fisch.  “We have used TCA and, because of serious environmental issues in our area that have proven to be very expensive over many years, we wanted a cleaning system with zero environmental concerns.”

“We manufacture hermetically sealed connectors and precision component parts for the ordinance industry.  Our components vary in size between 1 and 8 cubic inches.  We consumed 55 gallons per month of TCA and, although the material, even at the current rate, is not that expensive, the risks and adjunct costs are exorbitant.”

“All existing solvent- or water-based methods require the use of hazardous materials and require permits from water and/or air regulatory agencies,” Fisch continued, adding that their LCO2 system does not suffer from any of these deficiencies.  We have had a comprehensive number of production parts tested prior to our purchasing the system and found that it meets all of our needs including the elimination of potential etching of aluminum or rusting of steel.”
“The mental and financial relief of not having to deal with hazardous materials accidents, against which we can no longer buy insurance, is also of significant importance,” Fisch added in closing.

“Liquid CO2 Immersion Cleaning: The User’s Point of View”, Parts Cleaning, April 1999

CP Clare Corporation manufactures and supplies delicate electronic switches and relays for the communication, security, automotive, and medical industries.

“We require the surface of our components to be free of particles, trace residues, and oxides prior to high vacuum sputtering,” stated Mike Keys, senior manufacturing engineer.  “In the past, we used conventional CFCs and needed to eliminate them due to environmental regulations.  For the most part, the old system worked well; however, occasionally the solvent became contaminated and created problems.”

CP Clare was using a drum of solvent per week at a cost of $1,500.00 and an equal cost to dispose of the spent cleaning agent.  In addition to that, the company incurred an expense in maintaining a special environment for the cleaning system.

“We found that the ultrasonic solvent process had difficulty breaking the bond of the particle from the substrate,” remarked Keys.  “However, the CO2 composite spray cleaning process, being velocity-based, proved to do a much better and more consistent job for us.

“Another problem that was cured was the issue of re-deposition of contamination due to drag-out from one tank to the next.  In general, we chose CO2 composite spray cleaning because of its momentum transfer capability.  It also saves us time, money, and is more consistent than our old process.  We even noticed that our product’s electrical characteristics improved with CO2 spray cleaning, and carbon dioxide is flat out cheap compared to chemical processes.

“Another benefit is that we do not require any special emissions control area as we did with the solvent process,” Keys continued.  “So we clean and go straight into our vacuum system.  In my opinion, the system is simple to operate.  We worked with the process parameters in the beginning until we were satisfied, and now it’s as easy as pushing a button, walking away from the process, and coming back when it’s finished.  Our CO2 composite spray cleaning process is twice as fast as the old Freon process, with less operator interference and maintenance.”

Keys went on to state that the CO2 composite spray cleaning system is also extremely flexible.  By adjusting flow rates, the company has been able to minimize consumables.  Because CP Clare devices are prone to electrostatic discharge (ESD), the (optional) built-in ionization process that is part of the CO2 composite spray cleaning system was a valuable feature for their particular application.

“Today’s Forecast: It Looks like Snow”, Precision Cleaning, May 1999

Victor Wagner of Therm-O-Disc, Incorporated, a subsidiary of Emerson Electric, describes his company’s experience with a centrifugal liquid carbon dioxide cleaning system for removing silicone thermal test fluids from bi-metal disks.

“We went on-line in our London, Kentucky, facility on December 1, 1997,” said Wagner. “The assemblies we clean are electrical switch components with silver contacts.  The contacts tend to attract contaminates during the manufacturing and assembly processes, and, if improperly cleaned, will result in a rejected component.  The LCO2 cleaning system was acquired to replace vapor degreasing units.  “Our process engineers tested many alternatives to solvent cleaning,” Wagner remarked.  “Based on the cleanliness results, operating costs, and environmental benefits, they felt the CO2 cleaning system presented an excellent opportunity for us to move away from chemicals into a dry cleaning process with no future environmental risks.  The system cleans our parts as good as or better than our past vapor degreasing process.”
“Since going on-line we have not encountered any significant maintenance problems with the CO2 system.  The typical maintenance situation involves the replacement of “O” ring seals in the two pumps.  We drive the pumps with nitrogen gas generated from an on-site liquid nitrogen tank.  Currently, we consume approximately 600 pounds of CO2 every 10-14 days-depending on production-and have no disposal or environmental concerns related to our cleaning process (average cost of CO2 is $0.14 per pound).”

In summary, Wagner stated that his company is “very pleased” with their transition to LCO2 cleaning.  “I should add that we found the system to be very operator-friendly,” he noted.  “We have trained five different operators, and none of them had any trouble learning the functions and cleaning procedures.”

“Liquid CO2 Immersion Cleaning: The User’s Point of View”, Parts Cleaning, April 1999

Roy Sakaida, Supervising Water Resource Control Engineer, CRWQCB, provided a letter following a visit in 1994 to observe a live demonstration of one of the first commercial centrifugal liquid CO2 cleaning systems at Haskel International, Inc.

“Thank you for the invitation to the demonstration of your CO2 Cleaning System.”

“The system appears to be useful for replacing organic-solvent based cleaning of a variety of materials. Since CO2 is the only discharge to the environment and any contaminant removed from products in the cleaning process can be collected for proper disposal, there should be no problem with respect to requirements of this Board if the system is operated properly.”

Roy R. Sakaida
Supervising Water Resource Control Engineer
California Regional Water Quality Control Board

Letter to Deflex Corporation, June 10, 1994

Marek Dragon, contamination control engineer for Xolox Corporation, has good things to say about CO2 composite spray cleaning technology.

“We provide crash stop and actuator assemblies to the hard disk drive industry,” explained Dragon.  “Because our components go into hard disk drives, they must be very clean.  We have different requirements for different parts.  For example, a significant portion of our parts are allowed to have 250,000- to 0.5- micron particles (or smaller).  However, our requirements for other parts, such as our magnetic parts, are more stringent.  Our requirement for allowable magnetic particles is basically zero.”

According to Dragon, the company routinely subjects parts to particle- counting tests to confirm cleanliness.  Parts are also subject to a nonvolatile residue test (NVR).  Two to three micrograms of NVR per square centimeter is the upper limit.

“In the past, we attempted to use compressed ionized air to remove particles,” Dragon stated.  “We found the ionized air process to be effective at removing the larger particles, but ineffective at removing the smaller particles.  It was totally ineffective at removing the magnetically charged particles.  A few years ago we found the CO2 composite spray cleaning process to be very effective at removing all particles, including magnetically charged submicron particles.”

According to Dragon, the new process is meeting company requirements at approximately 3 to 5 seconds per piece.  The system has also proven itself easily adaptable to the automated processes within the operation and is used for many different applications.

“The CO2 used in the system is a recycled by-product, so for us there are no environmental concerns associated with the process,” remarked Dragon.  He added, however, that “since CO2 has the ability to deplete oxygen, you do need to consider the area of use.”

Xolox put a CO2 composite spray cleaning system into their operation and currently use it approximately 4 to 24 hours per day, depending on production.  “When properly applied with the appropriate fixturing, we could reduce our scrap rate by 90 percent,” claimed Dragon.  “That translates into a good yield improvement.”

“Today’s Forecast: It Looks like Snow”, Precision Cleaning, May 1999

Litton Guidance and Controls manufactures advanced inertial navigation and guidance systems for military and commercial aviation industries.

“At Litton, one product we produce is the accelerometer assembly for inertial navigation and guidance systems in missiles and aircraft,” said Bob Bauman, manufacturing/process engineer for Litton Guidance and Controls.

“Within the accelerometer there is a strong magnet that attracts metallic particles, and there are small gaps between moving parts within the instrument.  This particulate contamination is devastating to the performance of the instrument and was the largest cause for accelerometer failures during testing.  We can tolerate no particulate contamination on the magnet prior to, or after, assembly.”

According to Bauman, the company had previously used chemical sprayers to try to remove the particulates.  While the sprayers worked well on residue-type contamination and loose foreign material, they were relatively in effective in removing particulates held by the magnetic field.  “We resorted to hand cleaning particles out manually using sticky picks, which was time consuming and inconsistent,” Bauman stated.  “During our evaluation of the new options, we came across the CO2 composite spray cleaning process, and it is the best particulate removal method we have found.”

“With the CO2 composite spray cleaning system, Litton Guidance and Controls consumes approximately 50 pounds of CO2 every 10 to 14 days, depending on production.  The management team has found the new system to be cost effective as well as user friendly.  Regarding cycle time, a sub-assembly (containing three magnets, other components, nooks, and crannies) can now be cleaned in less than one minute compared with the 10 to 15 minutes it once took by hand.”

“We had not been able to achieve the same result with the other cleaning methods, especially cleaning the magnetically held particles.  We had established that particulate contamination was the primary cause of the failures and are convinced the yield improvement is significant,” concluded Bauman.

“Today’s Forecast: It Looks like Snow”, Precision Cleaning, May 1999

Robert Chittick of C-MAC Quartz Crystals, located in Essex, England, describes his company’s experience with a CO2 composite spray cleaning unit for removing submicron particles from piezoelectric crystal resonators during production.
Quartz crystal resonators (QCRs) are used in a myriad number of electronic devices and applications requiring precise timing.  QCRs vibrate at a fixed frequency when electrically excited.  QCR contamination results in poor stability and aging characteristics, and produces an effect called drive level dependence (DLD).  This means the activity of the QCR is non-linear with the applied drive level, and in extreme cases may not oscillate at all.  This is commonly called a sleeping crystal.  Thus removal of surface contaminations is critical to the functionality of QCRs and successful removal to produce a qualified timing device is indicative of successful removal of submicron contamination.  C-MAC tests proved that the CO2 composite spray technology could successfully reduce or eliminate DLD without damage to delicate QCRs.  Moreover the CO2composite spray cleaning technique allows for cleaning immediately following plating in their original containers, improving productivity of the cleaning operation.

“Using CO2 Snow to Correct Drive Level Dependence in Quartz Crystal Resonators”, Precision Cleaning, June 1997