Ultra Electronics CEMS
Contract Electronics Manufacturing &
Conformal Coating Services
Parylene coating
Properties and Advantages
Parylene coating is a vacuum deposition process, allowing very fine
adjustment of deposition thickness; typically 24microns on a PCB, but
adjustable in increments of a micron.
• Parylene has no parasytic effects on circuit operation
because of it’s very thin and uniform coating.
• Parylene is the coating most effective at preventing and
containing Tin Whisker growth from lead-free solder joints.
• Parylene delivers a high integrity waterproof coating
• Parylene is a tough and resilient material, yet it can be
removed using an air-abrasive process utilising an organic
abrasive that is non-static generative.
• Parylene is the default coating used in the aerospace and
defence sectors where electronics is required to operate
faultlessly in extremes of humidity, temperature and
vibration.
Characteristics and advantages
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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.
Typical applications
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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
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MIL-I-46058C, Type XY approved
Ultra Electronics CEMS
Contract Electronics Manufacturing &
Conformal Coating Services
Parylene coating
Properties and Advantages
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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 -200ºC and 150ºC
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
Hydrophobic
Barrier to ionic and moisture species
Chemical and fungal resistance
Non-contaminating coating and coating process -- no solvents, catalysts or other byproducts 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
Electrical Properties
PROPERTIES1
METHOD OR
CONDITIONS
Dielectric strength,
volts/mil short time ASTM D149-64
(1 mil films)
Corr. to 1/8"
ASTM D149-64
Step-by-step (1 mil
ASTM D149-64
films)
EPOXIES2
SILICONES2
URETHANES2
590
400-500
550
450-500
4,700
n/a
n/a
n/a
PARYLENE C
5,000
Volume resistivity,
ohms (23ºC, 50%
RH)
ASTM D257-61
(Dielectric -- 1
in2 mercury)
8.8 x 1016
1012-1017
2 x 1015
2 x 1011-1015
Surface resistivity,
ohms (23ºC, 50%
RH)
ASTM D257-61
(Dielectric -- 1
in2 mercury)
1014
n/a
n/a
n/a
60 Hz
3.15
3.5-5.0
7.75-3.05
4-7.5
103 Hz
3.10
3.5-4.5
n/a
4-7.5
106 Hz
2.95
3.3-4.0
2.6-2.7
6.5-7.1
60 Hz
0.020
0.002-0.01
0.007-0.001
0.015-0.017
103 Hz
0.019
0.002-0.02
n/a
0.05-0.06
ASTM D160Dielectric constant: 65T (Dielectric -1 in2 mercury)
Dissipation factor:
ASTM D15065T (Dielectric -1 in2 mercury)
Ultra Electronics CEMS
Contract Electronics Manufacturing &
Conformal Coating Services
Parylene coating
Properties and Advantages
106 Hz
0.013
0.03-0.05
0.001-0.002
n/a
1.Properties measured on parylene films, 0.001 inch thick.
2.Properties depend somewhat on deposition conditions.
Impact Resistance of Parylene C vs. Urethane and Epoxy
MATERIAL
THICKNESS IMPACT
(kg(Microns)
RESISTANCE cm)
Parylene C
Urethane
Epoxy
3
5
8
16
30
50
73
25
63
125
250
375
125
250
375
>85
>85
>85
>85
>85
>85
>85
23
25
51
74
>85
35
81
>85
Physical and Mechanical Properties
PROPERTIES
METHOD OR
2
2
2
PARYLENE C EPOXIES SILICONES URETHANES
CONDITIONS
Secant modulus,
psi
ASTM D882-56T
@ 1% strain
400,000
350,000
900
1,000-10,000
Tensile strength,
psi
ASTM D882-56T
@ 10% strain/min
10,000
4,000-13,000
800-1000
175-10,000
Yield strength, psi
ASTM D882-56T
@ 10% strain/min
8,000
Elongation to
break, %
ASTM D882-56T
@ 10% strain/min
200
3-6
100
100-1,000
Yield elongation, %
ASTM D882-56T
@ 10% strain/min
2.9
Density, gm/cc
ASTM D1505-57T
1.289
1.11-1.40
1.05-1.23
1.10-2.5
Index of refraction,
N 23
Abbe
refractometer
1.639
1.55-1.61
1.43
1.50-1.60
1
Ultra Electronics CEMS
Contract Electronics Manufacturing &
Conformal Coating Services
Parylene coating
Properties and Advantages
Water absorption,
24 hrs
ASTM D570-57T
0.06
0.08-0.15
12 (7 days)
0.02-1.5
Rockwell hardness
ASTM D785-65
R80
M80-M110
40-45 (shore A)
10A-230 (shore)
Coefficient of
friction:
ASTM D1894-63
Static
0.29
Dynamic
0.29
1.Properties measured on parylene films, 0.001-.0003 inch thick, except where specified.
2.Properties depend somewhat on deposition conditions.
THERMAL PROPERTIES OF PARYLENE C COMPARED WITH
EPOXY, SILICONE AND URETHANES
PROPERTIES
T (melting), °C
METHOD OR
CONDITIONS
Taken from secant
modulus temperature
curve
Taken from secant
T (glass transition),
modulus temperature
°C
curve
PARYLENE
EPOXIES SILICONE URETHANES
C
280
Cured
Cured
~170
80-100
120
-130
-10
T5 (where
modulus = 105), °C
Taken from secant
modulus temperature
curve
125
110
-125
-30
T4 (where
modulus = 104), °C
Taken from secant
modulus temperature
curve
240
120
-80
0
Linear
Coefficient of
Expansion (l05/°C)
ASTM 0696 - 44 (61)
3.5
4.5 - 6.5
25 - 30
10 - 20
0.17
0.25
Specific Heat @
20°C cal/g/°C
0.42
EXPANDED PARYLENE DETAILS
Uniform thickness and true conformality - the established process guarantees precise
control of thickness and inherent uniformity, especially critical in microelectronics applications;
no bridging, thin-outs, puddling, run-offs which are common problem with other coating
materials. Since it is based on a gas, Parylene can penetrate spaces which typical
conventional coatings can not cover: small recesses, crevices and holes and even the edges
and the inside spaces of very fine tubes.
Ultra Electronics CEMS
Contract Electronics Manufacturing &
Conformal Coating Services
Parylene coating
Properties and Advantages
Pinhole free - tough coatings as thin as 0.1 microns can be achieved without any voids.
Chemical, fungus and bacteria resistance -Parylene resists attack from exposure to most
acids, bases and solvents. It is an excellent inhibitor to the growth of fungus and bacteria.
Superior barrier properties -Parylene provides exceptional corrosion protection from
moisture, salt spray, corrosive vapours and other hostile environments. Its water vapour
transmission rate has been found to be significantly lower than most conventional coatings.
With respect to migrating ionic species, Parylene coatings have been proven to act as barrier
to extractable metals which otherwise will contaminate substrates.
Impressive mechanical strength - since it has high tensile and yield strength, Parylene is
used for encapsulating microcircuits because it increases the pull strength of wire and lead
bonds, face bonded chips and conductor bridges and therefore contributes significantly to
device integrity. Since its specific gravity is low, the Parylene layers are typically lighter than
most other functional coatings.
High dielectric characteristics - its extremely high dielectric strength combined with its
electrical stability in various media provide unique insulating property. The dielectric constant
and dielectric losses are low and unaffected by absorption of water vapours. Its volume and
surface resistivities are advantageously high because of the purity, low affinity to moisture
and in particular its freedom from trace ionic impurities present in conventional coatings.
Thermal stability - Parylene coatings remain stable at continuous temperatures as high as
130 deg.C in air, or 220 deg.C in the absence of oxygen. It has good mechanical properties
from -200 to 275 C.
Stress-free - since the polymerization of the film takes place on the substrate surface at room
temperature, there is no thermal or mechanical stress introduced during application, hence
original performance parameters of coated subjects are basically unaffected.
Particle immobilization - assures circuit integrity, preventing mobility of loose solder, wire
particles or other mobile debris left from manufacture. Pressed powder parts, ferrites,
ceramics, corrosive metals, glass and epoxy particulates can be positively stabilized.
If Parylene Coating is of interest to you please contact Ultra Electronics CEMS
Nick Mair
Sales & Marketing Manager
Ultra Electronics
Contract Electronics Manufacturing Services
Mobile: 07876 251 773
Skype: nickmair
Cems site: www.ultra-cems.com and group site: www.ultra-electronics.com
nick.mair@ultra-cems.com