Background
Goals
In
1976 we, while manufacturing audio equipment, encountered major problem with
switches which were being used at very low signal levels. Although mechanical
efficient, they demonstrated excessive RF demodulation effects, thin-film
distortion anomalies and intermittent microphonics.
All attempts to rectify these problems b cleaning or the application of
protective materials (such as oils), had only a shorter palliative effect.
Because
we were working with audio voltages as low as 80 microvolts, into impedance's
of from 40 ohms to 47 Kohms, we also encountered
unsatisfactory behavior from the connectors used in the system.
Being
aware of the probable evolution of low-power (CMOS) logic and the burden this
would place on connector systems, we decided in 1977 to develop a coating
treatment which could be applied to electromechanical contacts in order to make
them more reliable.
We
set forth several goals for the material: (not in order of importance)
- It
had to be easy to apply
- It
should have a long life, both on the shelf and in actual use. (>> 5
years).
- It
should be very stable, especially in its resistance to
"Varnishing" due to cross-linking caused by the presence of:
sulfur or sulfur-compounds on or in the vicinity of the contacts, the
presence of other curing agents either in elastomers or plastics used in
the connector or switch construction, or airborne contaminants
cross-linking-initiation compounds.
- While
the material should be capable of providing a limit to the degradation
the connector this limit should be sufficiently close to the normal
"New-condition-operating limit such that it would be within the
connector's operational envelope.
- The
material should have a switching-gradient of between 10,000 and 15,00 volts/inch when applied to insulating systems such
that its "unswitched" presence would
not cause leakage between adjacent contacts, yet it should have a low
effective volume resistance when in the "switched" condition.
- The
material should be a good lubricant.
- The
material should have the ability to permeate and/or lift corrosion
byproducts from the active surface of connections and keep the material
in suspension for very long periods of time and so prevent RF
rectification and thin-film distortion effects.
- The
material should be non-toxic.
- The
material should not require dilution with any CFC or other
environmentally sensitive solvent such as tri-chloro-ethylene
in order to provide a surfactant action. If it had to be thinned in order
to produce the desired film thickness, any diluants
needed should be as non-toxic as possible.
- The
material should not cause any adverse effects on any plastic used in the
electronics industry.
- The
material should be compatible with the majority of the elastomers used in
the electronics industry.
- Ideally,
the vapor pressure should be low enough so that it could be used in
satellite applications without having to be concerned with out-gassing.
- The
material should have a temperature envelope of from -70'C to at least
+170C.
Summary
It
took us from 1977 to 1982 to develop such a material and to satisfy ourselves
that we had met the design parameters. Extensive field testing was done during
the development and the material was released to the Canadian Armed Forces in
1983 for trials as well as being introduced to the consumer electronics market
at that time.
Revision
1
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.
MATERIAL
SAFETY DATA SHEETS ARE AVAILABLE ON REQUEST.
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.