"Electronic smog" is a term coined to cover electromagnetic interference from any source, whose potentials could affect the operation of robotic equipment. Obviously it is a term that could apply to almost any field where complex electronic equipment is being used, from biomedical electronics to avionics. Advancements in IC design have made it possible to reduce the power level of signal lines in electronic equipment, with worthwhile savings in power as well as in the size of electronics packages, but this, in turn, has made equipment more susceptible to outside electromagnetic interference.
There are two main steps involved:
These translate into such things as better shielding of equipment both from the containment point of view of the former, and from the exclusion point of view of the latter. Often it is difficult for a factory to control external sources of electromagnetic radiation (such as Radio & TV transmitters), and they must concentrate on reducing the damaging potential of electronic smog.
Robotics is especially susceptible to electronic smog, and in Japan, several deaths have been attributed to the malfunction of robotic equipment caused by outside electromagnetic interference.
While electronic smog may be combated through the use of better shielding design, this is of little use to equipment that is already installed.
In existing equipment the procedure is usually one of making sure that existing shielding is properly installed, all signal and power leads are protected by shielding, and that connector integrity is good. What is not always appreciated is that thin film rectification effects, can convert a poor connection into a radio receiver, and thus produce anomalous signals in the circuit using that connection. This is especially insidious in factories where the atmospheric environment may contain chemicals which will cause connector corrosion, or general breakdown.
Many of the corrosion products encountered in connectors are semi-conductors.
Although most robotic equipment is designed with environmentally secure connectors, once it has been in use for several years the integrity should be suspect.
If all the electromechanical connections in the equipment itself, and all its connections to outside equipment are treated with a material which minimizes or eliminates thin film or point-contact rectification effects, the susceptibility of the equipment to electronic smog will be reduced. It is also important that the shielding enclosures form a continuous shield. In this respect some equipment's shielding may be rendered ineffective by the painting of the shielding cases in the areas where the covers are screwed together. Sometimes spring "finger-stock" is used to ensure that a cover is sealed electronically all around its edges. Obviously, any paint on the finger stock or its associated contact surface will render the protection ineffective.
The same can be true of corrosion or tarnish on the surface of these shielding devices. Thus it may be necessary to treat the finger stock with a contact enhancer.
Stabilant 22 has proved to be effective at reducing the RF susceptibility of many different types of connectors.
Stabilant 22 is an initially non-conductive block polymer that under the effect of an electrical field and/or when used in a very narrow gap between metal contacts, becomes conductive. The electrical field gradient at which this occurs is set so that the material will remain non-conductive between adjacent contacts in a multiple pin environment.
Thus, when applied to electromechanical contacts, Stabilant 22 provides the connection reliability of a soldered joint without bonding the contact surfaces together.
While Stabilant 22 exhibits surfactant action it is not sold as a contact cleaner. Equally, it exhibits quite good lubricating properties but is not sold as a contact lubricant. Its métier is in its active properties when used in a connection and its other properties are a bonus.
Stabilant 22 can be used wherever electrical contacts are used, whether this is in connectors, or in switches. For example, one common use is to improve the connection reliability of socketed IC's in computers. In combating the effects of electronic smog, every non-power-interrupt connection in a system should be treated.
Granted that the material itself is expensive. However it is unique in having a very long useful life once in place. Unlike other so-called contact treatments Stabilant 22 will not cross-link (becoming varnish-like) under the action of sulfur-based curing agents in elastomers, cutting oil residues, or the sulfur-bearing free-machining metal alloys used in some contacts. Thus, in combating electronic smog through the use of Stabilant 22, other connector-related problems will be prevented increasing the mean-time-between failure of the equipment. In most types of service work, the cost of the time involved in removing and replacing a board will be much greater than the cost of the Stabilant used to treat the board. Here what is important is that not only will proper board treatment cure existing contact problems, it will prevent others from occurring thus eliminating the necessity of repeating the treatment at a later date! In other words, why do a job more than once?
In addition, Stabilants are one of the few viable alternatives to the repeated use cleaning solvents in electronic maintenance and manufacture, and thus are not subject to the increasingly stringent and restrictive legislation applicable to solvents.
Stabilant 22 is packaged in 15mL, 5OmL, lOOmL, 25OmL, 5OOmL and 1 Liter containers. Stabilant 22 is available in several forms. When it is a concentrate it is called Stabilant 22, when it is used as an isopropyl alcohol-diluted form, it is called Stabilant 22A. Conversely, when diluted with ethanol, it is called Stabilant 22E.
Because of the 4:1 dilution, a given size container of Stabilant 22A (for example) will cost about one-fifth the amount of a container of Stabilant 22, for it has only one-fifth the amount of the concentrate in it. Another packaging is available for industrial-bulk users. 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 diluant and saves the added cost of shipping isopropyl alcohol, as well as allowing the end-user to use an alternate diluant such as one of many other solvents.
The concentrate, Stabilant 22 is most useful where the connections are out in the open such as the card-type connections. Where the connections are not too easy to get at or where the user wishes to apply the material to something such as a socketed IC (without removing the IC from its socket) it is easier to use the alcohol diluted form, (e.g. Stabilant 22A). The alcohol diluant serves only to carry the concentrate into the connector.
Not at present. During the initial stages of our market research we did provide cans of the material, but the users found that in most cases it did not ease the application of the material, wasted many times the amount that actually got on the contact areas, and generally left a film of excess material that had to be cleaned up for appearances sake.
There was another consideration - this was that the fact that chlorofluorocarbon propellants might have been used. Although they are no longer used in spray cans, a HCFC is now substituted. However, although they are less harmful to the ozone layer, they are still a problem. Sometimes spray cans may use a highly inflammable mixture of Butane and Propane being substituted. Remember, very little Stabilant 22 is necessary to treat a contact, so why waste it?
No, it is important to remember that Stabilant 22 is an electrically active material which enhances conductivity within a contact without causing leakage between adjacent contacts. Thus large quantities of the material do not have to be "hosed" off as is the case with cleaners.
Normally, a final film thickness of from 0.5 to 1 mils of the concentrate is all that is necessary. In other words you want just enough to fill up the interstices between the contact's faces. Where you're using Stabilant 22A, you'll have to use enough so that once the alcohol evaporates the desired 0.25/0.05 to 1 mil film of Stabilant 22 remains.
This was made up at the request of several manufacturers who wanted a standard kit that they could issue to their service personnel. It consists of a 15mL container of Stabilant 22A and some Q-tips- as applicators, all in a small capped tube. The applicators are reusable.
Some manufacturers make large volume purchases, diluting the material as required for specific applicators used on their production lines.
Many end users have found that the material cuts their service costs so much that it is more economical to purchase Stabilant 22 in the larger size container, with its attendant savings, rather that run any risk of being without the material. The number of uses tend to increase as customers discover the diversity of the problems that can be solved by the material. One user routinely applies it to the flashlight switches and batteries it issues to its security guards and has reported that the number of requests for both batteries and replacement flashlights has dropped appreciably.
We could cite the fact that Stabilant 22 is used by many hospitals on their bio-medical electronics to improve reliability of the equipment where lives are at in the balance, we could cite the use of Stabilant 22 by many broadcasting networks to achieve the last measure of reliability in critical network switching applications, we could cite its use in navigational aids, or we could cite the years of use in the audio field where even consumers found the material easy to use and its results impressive; but we still feel that the best way to find out just how well it works is to try it out!
That's why we have samples available. Almost every service shop or manufacturer has equipment available where the switches or connectors have become erratic over the years. Use Stabilant 22A on them for a quick turnaround test, or use the material in field service and satisfy yourself.
Stabilant 22 has caused no skin reactions in tests. Because of its moderate detergent action it could remove skin oils and lead to chafing, therefore skin spills should be washed off and a lanolin-type lotion applied. In the undiluted form, Stabilant 22 is non-flammable, however if its temperature is raised above 200' C the decomposition products will burn. If small amounts are accidentally orally ingested it will cause bowel looseness. while ingestion of amounts in excess of 200 mL of the concentrate could lead to systemic collapse! Stabilant 22 has an LD50 of about 5 grams per kilogram body weight.
The consumer version of Stabilant 22 which was sold as TWEEK(TM) had been used for fourteen years without problems.
The 15mL and 50 mL containers have a "dropper" type cap that allows Stabilant 22A (or 22E) to be applied directly to such components as socketed IC's, switches, connectors, etc.
Some end users prefer to buy larger quantities and use industrial syrettes to apply the material onto connections. Camel's hair or sable brushes can be used to brush it on card-edge connectors. Cards can also have their edge connectors dipped into the dilute material.
In treating 'finger-stock' electronic seals, the concentrate, Stabilant 22 may be wiped on just as if the technician were using a protective oil.
Stabilants have been in some field trial applications for over fifteen years now without showing any sign of reduced effectiveness. The material has a high molecular weight and a very low vapor pressure, thus it is not prone to evaporation.
Once again let us emphasize the point that unlike some other contact treatments containing oils, Stabilant 22 will not cross-link when exposed to certain materials such as high-sulfur brass, or when used on connectors having elastomer or the most plastic components with accelerant and curing agents, or when used on contacts where cross-link promoting agents are present in the environment. The phenomena of "varnishing' does not occur with Stabilant 22.
Revision 3
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
The Stabilants are patented in Canada - 1987; US Patent number 4696832. World-wide patents pending. Because the patents cover contacts treated with the material, a Point-of-sale License is granted with each sale of the material.
Stabilant, Stabilant 22, and product type variations thereof are Trade Marks of D.W. Electrochemicals Ltd.
© Copyright 1987, '88. '89, '90 - D.W. Electrochemicals Ltd. This note may be reproduced or copied, provided its content is not altered. The term "contact enhancer", © 1983 Wright Electroacoustics.
NOTICE: This Application Note is based on customer-supplied information, and D.W. Electrochemicals is publishing it for information purposes only. In the event of a conflict between the instructions supplied by the manufacturer of the equipment on which the Stabilant material was used, and the service procedure employed by our customer, we recommend that the manufacturer be contacted to make sure that warranties will not be voided by the procedures.
While to our knowledge the information is accurate, prospective users of the material should determine the suitability of the Stabilant materials for their application by running their own tests. Neither D.W. Electrochemicals Ltd., their distributors, or their dealers assume any responsibility or liability for damages to equipment and/or any consequent damages, howsoever caused, based on the use of this information.
Stabilant, Stabilant 22, and product type variations thereof are Trade Marks of D.W Electrochemicals Ltd.
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