Miller-Stephenson Chemical MS-470C Urethane Conformal Coatings

• Superior toughness and abrasion resistance
• Reworkable and room temperature cure
• Solvent and discoloration resistant
• Fluorescent under UV light
• No cracking or crazing with vibration
• Easier to re-work than epoxy-based coatings

Superior Toughness, Abrasion Resistance, and Chemical Stability

Polyurethane coatings are available as either aerosol or bulk formulations. Both formulations provide excellent humidity resistance and far greater chemical resistance than Acrylic coatings. These Spray Conformal Coating are Single component Polyurethanes, while easy to apply, enjoy long pot life but sometimes require very lengthy cure cycles to achieve full or optimum cure. The cure cycle can be accelerated by the application of heat typically reducing cure times to less than 4-5 hours at 50% humidity.

Cleanliness of the substrate is of extreme importance for the successful application of a conformal coating. Surfaces must be free of moisture, dirt, wax, grease, flux residues and all other contaminants. Contamination under the coating could cause problems that may lead to assembly failures. MS-470C will cover 8.6 square feet at a 2-mil thickness per 14-oz. aerosol can.  MS-472C, the bulk liquid version of the product, is available in quarts and gallons for dip, brush, or spray applications and will cover 120 square feet per gallon at a 2-mil thickness. Printed circuit boards or electronics covered with urethane coating are repairable.  Simply heat the coating with a soldering iron to remove the components.

Urethane Conformal Coatings provide a barrier to air-borne contaminants from the operating environment, such as salt-spray, thus preventing corrosion.  Some typical application examples include high-reliability defense, automotive and aerospace, where coatings are used to protect against various combinations of moisture, aggressive chemicals and vapors, salt sprays, large temperature variations, mechanical vibration, and even organic attack (e.g. fungus). The protective nature of conformal coatings also means that they not only protect, but also serve to enhance product reliability and thereby reduce the potential cost and damaging effects of early field failures.

Application should be done in a well-ventilated area. Proper safety
equipment and chemical resistant gloves are strongly
recommended

1. Hold can 6 – 8 inches away from the assembly and apply a
   medium-light coating. Coating must be applied wet and
   allowed to dry on the surface of the assembly.
2. Allow coating to dry for 30-35 minutes at room temperature.
3. Apply 1-2 additional medium wet coats with 30-35 minutes
   between each.
4.  A total cured film thickness of 2 ± 1mil is recommended.
5.  Once spraying is complete, immediately invert can and purge
   the valve and actuator. This will prevent clogging and
   premature valve failure.
6. Drying and curing of the coating depends upon evaporation of
   the solvent and subsequent reaction of the polymer with
   moisture in the air at elevated or room temperatures.

Allow 48 hours minimum to reach room temperature before using cans stored or received during cold weather.

Post Application: Air dry for 30 minutes. Repeat up to 2-3 coats. The recommended cure schedule is 2 hours at 140°F/60°C and a relative humidity of 30% to 50%.  If the humidity level is less than 30%, place an open container of distilled water in the oven and allow to equilibrate.  The alternate cure, at room temperature and a relative humidity of 30% to 50%, will be tack free in one to four hours, semi-hard in one day, and fully cured in seven days.