Application Note 9 - Robotics
- (Reduction of Electronic Smog Effects in Robotics by using Stabilants)
- "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.
- What are the normal procedures for combating electronic smog?
- There are two main steps involved:
- Reduction of electromagnetic radiation from equipment
- Reduction of the susceptibility of equipment to electromagnetic interference
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 and 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.
- What else can be done?
- 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.
- 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.
- Where can Stabilant 22 be used?
- Stabilant 22 can be used in all types of connectors, at frequencies from to DC to several gigahertz, on fader's or potentiometer's, or in non-inductive (non-arcing) power-interrupt switches. The number of uses are almost limitless.
- Is Stabilant 22 just another contact cleaner?
- No, Stabilant 22 is a resident potentially electrically active material which through a synergistic combination of effects enhances conductivity within a contact without causing leakage between adjacent contacts. Thus large quantities of the material do not have to be "hosed" on, as is the case with cleaners.
- Is Stabilant 22 cost effective?
- As Stabilant 22 can be quickly applied to all contacts and connectors in a system, the often
difficult diagnostic determination as to which one of many contacts are erratic, can often be eliminated.
This can significantly reduce service time in the field and in many cases eliminates the need to return
boards for shop service or re-manufacturing. As any service manager knows, the diagnosis of electronic
problems, especially where intermittent failures are concerned, is often much more difficult than the
actual part replacement; as well as requiring service personnel of exceptional calibre. In many cases
the use of Stabilants can thus increase the efficiency of existing staff as well as allowing many
connector harness related problems to be handled at a much lower cost.
Many of our users have reported savings of from $250 to $3000 as a result of using $3 to $5 of the material. In many electronic applications demodulation (detection) of RF signals in connectors exhibiting thin film rectification effects can either reduce the signal-to-noise ratio or introduce artefacts which can disrupt data flow. Stabilants can cure these problems.
While Stabilants have demonstrated that they can cut the cost of both shop and field maintenance; their use in the manufacturing of electronic systems can speed up production as well as reducing rejections.
- How does Stabilant 22 work?
- Contact failure is rarely caused by a single factor. Thus, treatments that solve only one problem don't
necessarily offer a reliable long term solution. For example, cleaners do not prevent the re-entry of
contaminants or the reformation of contaminant films; nor do they offer any lubrication. They must be used
each time a connector gets dirty. Lubricants in themselves are rarely cleaners. Corrosion inhibitors are
neither cleaners nor lubricants and are often specific to one type of metal or plating. Unsaturated oils
used as contact treatments can cross-link under the influence of elastomer or thermoset plastic curing
agents and accelerants.
While resident in the connector, Stabilant 22 performs several concurrent functions. Its very presence in the contact gap will prevent the entry of outside contaminants. It has sufficient surfactant action to lift surface contaminants and hold them in suspension. In cases where corrosion products are present, Stabilant 22 will penetrate them and prevent rectification effects. Due to its high dielectric constant it will act to form a capacitive layer which is in parallel with whatever residual resistance exists in the contact increasing the passage of AC signals. Given sufficient DC bias within the gaps of the contact the thin film of Stabilant will "switch", conducting by quantum tunnelling, and thus limit the resistance of the contact to a serviceable level.
- 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 the difference in use of these materials?
- Stabilant 22 is most useful where the connections are out in the open - such as card-edge connectors or where the lubricating properties of the material are useful -such as an aid to installing microprocessor IC's or on switches. 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 (Stabilant 22A or Stabilant 22E). The alcohol diluent serves ONLY to carry the concentrate into the connector.
- What packaging is available?
- Many manufacturers make large volume purchases, diluting the material for specific applicators used on their production
lines. We can supply the concentrate (Stabilant 22), in 0.5 mL, 15 ml, 5O mL, lOO mL,
25O mL, 5OO mL and 1 litre bottles. The dilute (Stabilant 22A or Stabilant 22E, the
latter which is available in a limited number of bottle sizes except on special order), are available in 5O mL,
lOO mL, 25O mL and 5OO mL containers. We do not have a 1 litre container of the dilute as 500 mL is
the largest size bottle that can be shipped by air (in single or multiple packages) without additional restrictions. We
maintain our stock in depth and ship most orders the next day that they are received. ( On large quantities , more time
may be required) For companies which want to use the material as a stock store item, we can produce custom labels with
your part or stock number. The 15 mL sizes are in dropper bottles, and these are available on request for the
50 mL sizes as well.
Custom labelling has been provided for many manufacturers who wish to assign their own stock control number, or to distributors who wish to market the product under their own logo. Obviously this requires purchase in of the product in suitable quantities.
- Is it available in a spray can?
- No. Why waste the material? We would like to think we are environmentally responsible and safety conscious. This ruled out
the use of either a chlorofluorocarbon or highly inflammable mixture of butane and propane as a propellant.
In addition even Stabilant 22A for example, has only about 71200th the solvent impact as conventional contact cleaning solvents, over a three year time span. As Stabilant 22 contains no solvent it has absolutely minimal environmental impact and is, therefore, becoming the treatment of choice for many service organizations!
- Just how much should be used?
- Normally, a final film thickness of from 0.5 to 2 mils of the concentrate is all that it necessary. In other
words, you want just enough to fill up the interstices between the contact's faces. When using Stabilant 22A,
or Stabilant 22E, use enough so that once the isopropyl alcohol (or ethyl alcohol), evaporates the desired
0.5 to 2 mil film of Stabilant 22 remains.
In applications to moving surfaces, such as in slip-rings or potentiometers, film thickness should be minimized to the point where "hydroplaning" won't occur.
- What is the 15 ml service kit?
- 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 15 ml dropper bottle of Stabilant 22A and some applicators, all in a small capped cardboard tube that can be tossed into a tool box without damage. As noted, we can provide these kits with special labels when large volume orders are involved.
- How can I be sure that Stabilant works?
- 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 22/22A/22E on them and satisfy yourself. A word of caution. Don't try to evaluate Stabilant 22's performance on brand new connectors. Instead, use it on connectors that are corroded, or dirty or just plain unreliable. We are sure that any organization dealing with electronics will have at least one piece of unreliable equipment on which the Stabilants can be tested!
- Is Stabilant hazardous to use?
- Stabilants have very low oral toxicity. Under normal workplace conditions no skin sensitization effects have been noted. In the undiluted form, it is non-flammable although if heated above 200° Celsius the decomposition products would burn. And Stabilants are environmentally friendly materials.
- Can Stabilant be used by untrained personnel?
- Thousands of applications of the consumer version of Stabilant 22 have been made over a period of several years now without any reported problems.
- What is the best way to apply Stabilant to a contact?
- The 15 ml (and the 50 ml) container have "controlled-dropper" type caps that allows Stabilant 22A to be applied directly to such components as socketed IC's, switches, connectors, etc. Some end users prefer to use industrial syrettes to apply the material. Camel's hair brushes can be used to brush it on card-edge connectors or they could be dipped into the dilute material. Most metering type liquid dispensing systems can be used as well.
- 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".
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