Parylene coating is the ultimate conformal coating for assemblies that are likely to be exposed to extreme excursions in temperature and humidity.
Typical applications demanding Parylene coating
Avionics systems (moving rapidly between low and high altitudes, with resultant changes in temperature and humidity) Marine systems, (both sub-sea and surface, exposed to extremes of moisture & humidity) Critical assemblies compliant with RoHS lead-free regulations (where the very real risk of tin-whiskers causing failure compels the use of Parylene to control that risk.)
Parylene is a typically thin vacuum deposited layer, commonly between 20microns and 24 microns when coating a pcb assembly, providing high voltage isolation and physical protection whilst also being the perfect waterproof jacket!
Being vacuum deposited the coating covers the assembly very evenly, penetrating the smallest orifice, and so the combination of being a thin layer and one of uniform thickness prevents parasytic effects, even on high frequency circuitry, which if spray or dip coated might suffer performance variations because of a variable thickness.
Parylene is the ultimate solution; high level protection without any side effects!
There are only a handful of Parylene coating facilities in the UK and Ultra Electronics CEMS Weymouth operation is pleased to offer this coating process as an in-house service at preferential rates, having a bench-top machine for small assemblies and a larger free-standing machine for larger assemblies or larger volumes.
Parylene coating can be removed when required using an air abrasive system, the abrasive being organic and non-static generative.
Characteristics and Advantages
- Hydrophobic, chemically resistant coating with good barrier for inorganic and organic media, strong acids, caustic solutions, gases and water vapour.
- Excellent electrical isolation with high voltages and low dielectric constant
- Micropore and pinhole free starting from 0.2 µm layer thickness
- Thin and transparent coating maintaining insulation gaps, suitable for complex substrates also coats the edges
- Coating without temperature load of the assemblies, coating takes place at ambient temperature in the vacuum
- Highly corrosion resistant
- Completely homogeneous surface
- Thermally stable up to 220 °C, mechanically stable from -200 °C to +150 °C
- Low mechanical stresses
- Resistant to friction
- Very low permeability to gases
- High electrical impedance
- Dielectric coating (e.g. Cores/coils)
- Hydrophobic coating (e.g. biomedical hoses)
- Microwave electronics
- Sensors in rough environment
- Electronics for space travel and military
- Corrosion protection for metallic surfaces
- Reinforcement of micro-structures
- Abrasion protection
- Protection of plastic, rubber, etc. from harmful environmental conditions
Additional Advantages / Benefits
- MIL-I-46058C, Type XY approved
- UL listed
- Completely pin-hole free barrier coating
- Fully conformal on any type of surface material or design
- Inert transparent polymer
- Thermal mechanically stable between -200°C and 150°C
- Extremely high dielectric 5,000 volts per 0.001" minimum
- Excellent adhesion properties
- Low stress coating that does not form sites prone to crack initiation
- Low / minimal impact on package cooling
- Barrier to ionic and moisture species
- Chemical and fungal resistance
- Non-contaminating coating and coating process -- no solvents, catalysts or other by-products are introduced during coating
- Entire process is accomplished at room temperature, alleviating temperature stress on parts
- Particle encapsulation / immobilization
- No outgassing (NASA approved)
- High reliability - Suitable for military or commercial applications
- Light weight - compared to other coatings
- Stress-free coatings - Sensitive circuitry unchanged by coating
- Transparency - Thin films can be of optical quality
- Mechanical - High tensile and yield strength