Application Note 10 - Environmental Impact
- What are the prospects for restrictions on contact cleaning solvents?
- The individual service manager is not generally aware of the large amounts of cleaning solvents that are used in the electronics industry.
Setting aside those that are used in 'closed" systems (where release of solvents to the atmosphere is minimized or virtually eliminated),
hundreds of thousands of gallons of cleaning solvents are use each year in the electronics industry. The environmental impact of these is
considerable, as a substantial portion of them evaporate into the air.
Not only do solvents present a potential hazard to human health in the workplace, they often combine with other chemicals, forming layers of often-phototropic smog. While few solvents have the potential impact of the chlorofluorocarbons, they are nevertheless of considerable concern to environmental authorities and concerted efforts are underway to limit their use. A measure of things to come are California (and other States) restrictions on the amount of solvents permitted in paints and other coatings, and strict regulations governing processes which have the potential to release any solvents into the atmosphere (such as compressed-air based paint spraying).
Manufacturers and service organizations operating coast-to-coast are finding it increasingly difficult to cope with the numerous and differing standards as to what an acceptable cleaning solvent and its permissible level of usage. This makes the use of "centralized stores" purchasing, with its attendant economies, quite hard to manage. Indeed what may be legal in one area of a state may well be banned in another area of the very same state.
- What is Stabilant 22?
- Stabilant 22 is an initially non-conductive block polymer which when used in a thin film
between metal contacts becomes conductive under the effect of an electrical field. This occurs
at an electric field gradient such that the material will remain non-conductive between adjacent
contacts in a multiple pin environment. In addition, Stabilant 22 exhibits surfactant action,
as well as lubrication ability providing a single component resident solution to virtually all
When applied to electromechanical contacts, Stabilant 22 can provide the connection reliability of a soldered joint without bonding the contact surfaces.
- Does the action of Stabilant deteriorate with age?
- In some field trial applications lasting over fifteen years Stabilant 22 has shown no sign of reduced effectiveness. With a high molecular weight and a very low vapor pressure, little is lost by evaporation. Unlike some other contact protection oils, Stabilant 22 will not cross-link when exposed to free machining materials such as high sulfur brass, or when used on contacts where agents used to promote cross linking of thermosets or elastomers are present in the environment or in the actual connector components. Unlike non-saturated oils, Stabilant 22 does not "varnish".
- In what forms is Stabilant available?
- The Stabilants are available in several forms. As a concentrate (Stabilant 22), an isopropyl
alcohol-diluted form (Stabilant 22A), and an ethyl alcohol diluted form (Stabilant 22E).
For example, a given size container of Stabilant 22A will cost about one-fifth the amount of a
container of Stabilant 22 as it contains only one-fifth the amount of the concentrate. Another form
of packaging is available. Stabilant 22S packages the concentrate such that it occupies one-fifth the
volume of an otherwise empty container. This allows the end-user to add his own diluent, and thus saves the
added costs of shipping the diluent (e.g.: isopropyl alcohol), as well as allowing the end-user to use an
alternate diluent such as one of the Freon-based solvents.
In addition a 0.5 ml vial of Stabilant 22A is available for manufacturers to include with plug-in circuit boards
- What is meant by a piece of electronic equipment's solvent burden/year?
- Solvent burden/year is the average amount of cleaning solvent used per year to keep a piece of electronic equipment operating over its useful life.
- How did the use of Stabilant 22A or Stabilant 22E change the solvent burden/year?
- In the trial use of a solvent to clean contacts in an older computer, we found that it took about 20 mL of an isopropanol-perchloroethylene
based material to clean a 100-contact card-edge connector. Even though some was left on the wiper used, it too evaporated. The equipment
became erratic in operation four months later, and the contacts had to be re-cleaned. In the proceeding year, the same approximate pattern
had been repeated to the point where we could safely say that the annual solvent usage for that set of contacts was about 60 mL. The next
time that we had the equipment malfunction we used 2mL of Stabilant 22A which released 1.6 mL of isopropanol to the atmosphere. No further
service was needed for three and a half-years, (the equipment was sold in working order), thus the solvent burden of that connector was
about 0.46 mL/year. This is a reduction in solvent burden of 130:1.
Had the concentrate (Stabilant 22) been used there would have been no solvent burden as the vapor pressure of that material is very low and virtually no evaporative losses take place.
- Do Stabilants contain any Ozone Depleting Chemicals?
- Stabilants do not contain any ODC's such as CFC'S, HCFC's or Trichloroethylenes, nor are such chemicals used in their manufacture.
- How about materials that cannot be imported to or sold in some areas?
- Neither the Stabilants themselves, nor any of the inks used on their labels or packaging, contain Lead, Cadmium or Hexavalent Chromium.
- Other factors in the use of Stabilants:
- Neither Stabilant 22, Stabilant 22A, nor Stabilant 22E are subject to the TSCA (Toxic Substance Control Act) nor are they reportable under SARA Title 111.
- What about disposal of Stabilant material or Stabilant-treated equipment?
- As noted, Stabilants are not a chelating agents and thus will not cause heavy metals to become concentrated
in effluents. And while there is no evidence of toxicity to marine or littoral life, we recommend, subject to local
ordinances, that surplus or contaminated Stabilant materials be destroyed by incineration.
- Halogen content: 0 ppm (ug/g)
- Sulfur content: 0 ppm (ug/g)
- For United States end-users:
- Stabilant 22 is not a hazardous waste when discarded as defined in 40CFR261.337
Stabilant 22 is not a halogenated solvent when spent as defined in 40CFR261.317,
The total Organic Carbon Content (TOC) of Stabilant 22 is 28%
- As the useful life of the Stabilants is generally well in excess of five years, the reduction of solvent burden when using either
the isopropanol diluted Stabilant 22A or the ethanol-diluted Stabilant 22E, could be as much as 200:1, by volume alone,
for the connector in a piece of electronic equipment.
Granted that the Mean Time Between Failure of 4 months is much shorter than a typical MTBF for most electronic equipment, the amount of solvent used was also minimized by careful application. While even a 50:1 reduction in solvent burden is worthwhile, the total elimination of solvent burden by the use of the concentrate Stabilant 22 is even more significant, Stabilant 22 is not a chelating agent, a matter of concern to both those industries producing heavy metal waste, and to the Nuclear power generating industry.
As Stabilant 22 contains no solvents and has an exceptionally low vapor pressure, it is technically not subject to the various rules and regulations governing coatings such as paints and varnishes, and in California's Southwest, the amounts of isopropanol or ethanol (as a solvent) involved in the use of Stabilant 22A or Stabilant 22E, are so small, on a daily basis that there is generally no problem in obtaining a letter of exception from the appropriate agencies. As Stabilant 22A or Stabilant 22E are not packaged in quantities sufficient to be affected the various acts it does not require special labelling in California.
Stabilants™ are a product of Dayton Wright research & development and are made in Canada
NATO Supply Code 38948
15 ml of S22A has NATO Part # 5999-21-900-6937