Application Note 39 - Stabilant use on PLCC's

Application Note 39 - Stabilant use on PLCC's

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 contact problems.

When applied to electromechanical contacts, Stabilant 22 can provide the connection reliability of a soldered joint without bonding the contact surfaces.

How can Stabilant 22A/22E improve the performance of PLCCS?
PLCC and socket
Stabilant 22A or Stabilant 22E provide a quick an effective way of increasing the reliability of PLCC devices through improvement of the device connections.

The application is simple. Using the dropper-insert on the 15 mL or 50 mL bottle of Stabilant 22A (or 22E), apply small amount to the connections on the edges of the device and/or the contacts in the socket before insertion of the device.

A soft camel's hair brush can also be used to spread the material some saving in the amount that has to be applied. As Stabilant 22A or Stabilant 22E is just the Stabilant 22 concentrate thinned 4:1 with an alcohol, the diluent will evaporate leaving a thin film of the concentrate resident on the contacts. Note that from 0.25 t 0.5 Mil film-thickness of the concentrate is all that is required. The concentrate has a very low vapor pressure, and a life expectancy of over 12 years in service. During application the usual precautions should be taken against static discharge.

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.
Is it environmentally acceptable?
Yes. Stabilant 22 itself is non-toxic and only the isopropanol diluent in Stabilant 22A represents a flammability and a very minor health hazard.

Even Stabilant 22A has only about 11200th 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!

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".

Revision 2

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