avionics adhesives
Materials Engineering and Adhesive Expertise
Solve Avionics Challenge
In aerospace applications, real estate is always at a premium, especially when it comes to
avionics. Fitting all the necessary control and monitoring systems into a cockpit is a fine art.
Crane Aerospace & Electronics supplies critical systems and components to the aerospace
and defense markets. The company’s expertise includes microelectronics solutions that
reduce weight and increase reliability. Advanced microelectronics packaging solutions
require a strong durable enclosure to protect sophisticated, dense microelectronic
components. For Crane, a unit can be typically chemical conversion coated (with iridite
or Alodine), painted with black Mil-Std paint or anodized. The materials are selected for
their corrosion resistance, strength, light weight, and low magnetic properties.
But what protects the unit itself from scratches during assembly and test?
Microelectronics solutions reduce weight and
increase reliability.
Protecting the Unit
Every inch of an avionics unit is typically filled with densely populated components
intricately connected and squeezed into a compact footprint. The unit that protects the
electronics is critical. The unit could be an aluminum alloy with a chemical conversion
coating of iridite or Alodine. Iridite and Alodine are gelatinous chemical films which provide
a barrier medium to retard corrosion on aluminum surfaces and enhance adhesion
of subsequent coatings such as Mil-Std black paint.
To prevent the unit from scratching during testing, a very thick and expensive tape is used
to wrap the outside of the unit – side, back, and front surfaces. The tape is 6 mil thick
and very stiff. Similar to heavy duty masking tape, it was originally used in the manufacture
and assembly of outdoor signage. Crane has used such a tape for years. Unfortunately
for Crane the tape manufacturer they were using had recently decided to discontinue the
tape and so a suitable replacement was required.
Crane Looks for a Solution
In addition to thickness to cushion the unit, the replacement tape needed to exhibit strong
adhesion properties – strong enough to endure thermocycling during testing. Thermocycling
exposes the unit and its electronics to simulated temperatures that could be found in an
aircraft. Repeated cycles of heat and cold can weaken the adhesive bonds of most tapes.
To make it even more challenging, once thermocycling was complete, the tape needed to
be easily removed – without leaving any residue.
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To ensure that it met requirements, the tape was tested in the
production process and approved by the line workers. In addition,
it was more flexible and easier to use than the original tape.
According to the production workers, application was faster
and simpler.
A tape with a strong adhesive bond is required to protect the component undercarriage.
Identifying an adhesive tape to meet these specifications required
the assistance of a converter with adhesives expertise. Fabrico
combines materials converting and bonding, joining, and sealing
expertise with an impressive supplier and partner network.
Fabrico investigated several possible solutions, including
foam backed tape.
During the investigation of available adhesive tapes,
3M Scotch® Performance Masking Tape 234 stood out as
a possible replacement.
The tape is a good solution for general industrial applications and
will function during baking cycles up to 121°C, with adhesion of
34 oz./in. and tensile strength of 27 lbs./in. The tape has a strong
adhesive bond and adheres to the undercarriage. When removed,
there is no adhesive residue.
The tape seemed perfect – however there was one problem –
thickness. Typically the tape is available in 5.4 mil thickness –
not thick enough to meet the protection requirements. Using a
version of the tape at 2 mil thickness and experimenting
with different layers, a solution was discovered. Three layers
of 2 mil tape were laminated together and then slit to the
appropriate width. The laminated tape had the desired
thickness, stuck well to the chemical conversion coated
unit, and was quickly removed after assembly, without
leaving a residue.
There was an even more exciting benefit. The laminated tape
was much more cost-effective than the original tape. In fact,
it was 30% less expensive.
The ability to investigate a number of options and to apply
laminating capabilities to meet the desired thickness proved
critical to this solution.
Material Partners
Fabrico has strategic relationships with world-class materials
suppliers, such as 3M, to assist its customers in selecting the
best material for the intended use and to expedite materials
sourcing. Whether adhesive films or liquids, all critical material
properties are considered in any Fabrico project, including
chemical, thermal, and moisture resistance.
With more than 30 years of materials experience, Fabrico
engineers also understand the impact of material selection
on the overall manufacturing process, and design material
systems that optimize production efficiency and improve
overall cost-effectiveness.
Fabrico Headquarters
4175 Royal Drive, Suite 800, Kennesaw, GA 30144
Phone: 678-202-2700 | Fax: 678-202-2702
Toll Free: 800-351-8273 | E-mail: info@fabrico.com
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Fabrico is a trademark of EIS, Inc.; Scotch is a registered trademark of 3M Company.