Parylene Technology for Electronics
Rakesh Kumar, Ph. D.Vice President of Technology
CTEA (Central Texas Electronics Association) Electronics Design & Manufacturing Symposium Tuesday, February 5, 2013
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
OutlineParylene Technology for Electronics
• Packaging Challenges
• Advancement in Parylene
• Characterization & Qualifications
• Practical Issues
• Conclusion
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
SCS is the direct descendant of Union Carbide Corporation– Unbroken transfer of technology and Intellectual Properties
– Over 40 years of Parylene applications experience
SCS manufactures its dimer to ensure high quality and formulation
SCS - the global leader in Parylene coating solutions– Parylene variants, coating center locations, process development,
coating technologies, equipment design and manufacture, regulatory support
• 11 worldwide coating centers– Americas: Costa Rica and United States (5)
– Asia: Japan and Singapore
– Europe: Czech Republic, Ireland and United Kingdom
Specialty Coating Systems
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
ISO & AS 9100 Registration
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Challenges in Electronics
• Smaller, 2D-3D forms
• Protection from moisture and other contamination
• Higher operating temperatures
• Higher frequency operations
• Improved processing methods
• Product differentiation (via improved engineering)
• Reliability of components in corrosive/harsh environments
• Controlling degradation due to time, physical and chemical attack
• Industry and government regulatory compliance
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
• Increasing package performance, functionality and reliability (e.g. smaller pitch is accompanied by smaller solder balls, which can affect structural integrity)
• Miniaturization, e.g. MEMS, NEMS & other devices
• Reducing stress and increasing reliability, such as underfill, in board-level assemblies and stress-absorbing layers and bump structures
• Achieving required mechanical tolerances for aligning chips to small pads
• Assembling or placing single and multi-die stacks
• Addressing the issues of stiction, e.g. MEMS
• Reducing interconnect fatigue
• Making reliable contact to the bond pads
Wafer Level PackagingProtection and Reliability Challenges
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
• Electromigration/short circuit
• Drift of component parameters
• Transient electrical stresses/ failure/ electronic charge induced damage
• Environmental damage to electronics –atmospheric contamination and moisture
• Excessive heat/high temperature failure
• Electromagnetic interference (EMI)
• Mechanical failures
• Corrosion in electronics
• Packaging stresses
Sensitive & Power Electronics Reliability Issues
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
• Completely conformal
• Unique, vapor-deposited, high-performance polymer coating
• Unique combination of performance, protection & durability characteristics
• Suited for complex situations where a durable coating solution is required
• “Green” material and application process
Why Parylene Conformal Coating ?
Parylene Coating Liquid Coating
• Able to coat a variety of substrates• Uniform, no pooling/voids• Stress free application• Low dielectric constant
• Optical clarity/transparency• Excellent electrical insulation• Excellent chemical and moisture barrier• High dry-film lubricity
• Environmentally safe• Extremely thin• Pinhole and defect free• Biostable and biocompatible
Advantages of Parylene
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Advances in Parylene
F2C CF2____
n
Parylene HT®
High Temperature Fluorinated Parylene
H2C CH2____
n
H2C CH2
Cl
____n
H2C CH2
Cl
Cl
____n
Parylene N
Parylene C
Parylene D
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Advances in Parylene
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Parylene C; As depositedE.E. Hui, UC Berkeley
Parylene CharacteristicsTruly Conformal
0.001” (1 mil) gold wire with a 1.5m Parylene C coating
Liquid Coating
Parylene Coating
Parylene C on MEMS
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Thermal CharacteristicsR
elat
ive
sam
ple
wei
ght [
%]
Atmosphere: Air
Heating rate: 10 C/min
Temperature [°C]
T 5% = 535 °C
0 100 200 300 400 500 600 700 800 90020
30
40
50
60
70
80
90
100
110
Temperature [°C]
Rel
ativ
e sa
mpl
e w
eigh
t [%
]
Atmosphere: Nitrogen
Heating rate: 10 C/min
T 5% = 539 °C
Parylene HT
0 100 200 300 400 500 600 700 800 900
0
20
40
60
80
100
Parylene HT
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Thermal AgingParylene HT
Dielectric and Tensile Strength
1000
3500
6000
8500
control 250C-24h
250C-168h
250C-500h
250C-1000h
350C-24h
350C-168h
350C-500h
350C-1000h
400C-24h
Temperature and Time
Diel
ectri
c St
reng
th
(vol
ts/m
il)
1000
4000
7000
10000
13000
Tens
ile S
treng
th (p
si)
Dielectric StrengthTensile Strength
1000
3500
6000
8500
control 450C-30m 450C-60m 450C-180m 500C-0m 532C-0m
Temperature and Time
Diel
ectri
c St
reng
th
(vol
ts/m
il)
1000
4000
7000
10000
13000
Tens
ile S
treng
th (p
si)
Dielectric StrengthTensile Strength
Long-term
Short-term
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Thermal AgingParylene HT
Water Vapor Transmission Rate (WVTR) and Modulus
0
0.2
0.4
0.6
0.8
Control 250C-24h
250C-168h
250C-500h
250C-1000h
350C-24h
350C-168h
350C-500h
350C-1000h
400C-24h
Temperature and Time
WVT
R cc
/(100
in2-
day)
100000
200000
300000
400000
500000
Mod
ulus
(psi
)
WVTR Modulus
0
0.2
0.4
0.6
0.8
Control 450C-30m 450C-60m 450C-180m 500C-0m 532C-0m
Temperature and Time
WVT
R in
cc/
(100
in2-
day)
100000
200000
300000
400000
500000
Mod
ulus
(psi
)
WVTRModulus
Long-term
Short-term
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Thermal Shock
• Tested in accordance with Mil-STD 202, Method 107, test condition B. • After completion of the temperature cycling, the specimens were conditioned
at 25oC and 50%RH for 24 hours before appearance and dielectric withstanding voltage.
Thermal Shock Test Condition B (5 cycles )
Step Exposure condition Exposure time1 - 65 oC, +0, -5 30 min dwell
2 25 oC, +10, -5 5 min max
3 125 oC, +3, -0 30 min dwell
4 25 oC, +10, -5 5 min max
Results 1. Appearance compared to control sample at 10X: Passed
The coating was free from bubbles, pinholes, whitish spots, blistering, wrinkling, cracking and peeling.
2. Dielectric Withstanding Voltage: PassedApplied voltage : 1500 VAC rms for 60 seconds, leakage current : 1.02 to 1.04 µA
Parylene Types Tested
Parylene N
Parylene C
Parylene HT
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Moisture Resistance -Insulation Resistance
Insulation ResistanceParylene HT Mil Requirement
Insulation Resistance 1.7 x 1013 > 2.5 x 1012 (Ohms )Test Method
Tested in accordance with Mil-STD 202, Method 302, test condition B (Temp: 230C, RH: 45%). Insulation resistance measured were taken using a megohms bridge at 500 volts DC, with an electrification time of one minute.
Tested in accordance with Mil-STD 202, Method 302, test condition B (Temp: 650C, RH: 90-96%)
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
UV Stability
Parylene films were exposed to radiation from a bank of fluorescent lamps using the following parameters:
- Device used : QUV - Type of test: Accelerated Weathering- Test method: ASTM 154 - Irradiance: 0.77 Watts per square meter - Source: UVA 340 lamp
0
2
4
6
8
10
12
0 100 250 500 1000 1250 1500 2000
Visual color, cha
lk, crack ra
ting
[Scale: 0
‐‐Ve
ry poo
r , 10 Excellent]
UV exposure time (hrs)
Parylene N
Parylene CParylene HT
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Chemical Resistance
Chemical Tested Parylene N Parylene C Parylene HT
10% Nitric Acid, RT 0.1 0.1 0.0
10% Nitric Acid at 75oC 0.2 0.1 0.0
70% Nitric Acid, RT 0.2 0.2 0.0
70% Nitric Acid at 75oC Brittle 1.8 1.2
10% Sulfuric Acid, RT 0.1 0.3 0.0
10% Sulfuric Acid at 75oC 0.2 4.1 0.0
95-98% Sulfuric Acid, RT 0.2 0.4 0.0
95-98% Sulfuric Acid at 75oC 5.3 5.1 2.8
% Swelling
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Parylene Barrier Properties
Water Vapor Transmission Polymer N2 O2 CO2 H2
Parylene N 3 15.4 84.3 212.6
Parylene C 0.4 2.8 3 43.3
Parylene HT 4.8 23.5 95.4 –
Epoxy (ER) 1.6 4 3.1 43.3
Polyurethane (UR) 31.5 78.7 1,181 –
Silicone (SR) – 19,685 118,110 17,717
Gas Permeability at 25°C, (cc•mm)/(m2•day•atm)a
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Corrosion ControlParylene HT
Uncoated (left side) and Parylene HT coated (right side) PCB boards after 144 hours salt fog test in accordance with ASTM B117-(03)
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
CTE & Microorganism Resistance
0.0
20.0
40.0
60.0
80.0
100.0
CT
E (
pp
m)
Temperature ( °C )
36 ppm at Room Temperature
0
1
2
3
4
Effe
ctiv
enes
s Ra
ting
Parylene N Parylene C Parylene HT Filter Cotton Duck
Test Samples
7 days14 days21 days28 days
Rating: 0 = None
1= Traces of growth (less than 10%)
2= Light growth (10-30%)
3= Medium growth (30-60%)
4= Heavy growth (60% to complete coverage)
Test Method: ASTM G-21
Coefficient of Thermal Expansion Microorganism Resistance
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Flexibility & Flame Resistance
• Flexibility: Tested in accordance with method 6221 of FED-STD-141 (bent 180 degrees on a 1/8” mandrel)
– There was no evidence of cracking or crazing of the coating on any of the Parylene N, C and Parylene HT specimens tested.
• Flame Resistance: Tested in accordance with method 2021 of FED-STD-406.
– All Parylene N, C and Parylene HT specimens were determined “self extinguishing”.
Parylene Type(Four Specimens of
Each Type)
Time of 1st
Application(Seconds)
Time of 2nd
Application (Seconds)
Results
Parylene N 30 30 Self Extinguishing
Parylene C 30 30 Self Extinguishing
Parylene HT 30 30 Self Extinguishing
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Improvement in Wire Lead & Bond Strength
• A bare 1-mil aluminum wirehas a typical bond strength of 3to 5.5 grams.
• A 1-mil coating of Parylene Cover the wire and bondincreases that strength tobetween 60 and 70.
Wire-bond strength vs. Parylene C coating thickness on a hybrid-to-chip lead
Parylene HT is expected to improve wire lead and bond strength similarly.
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Salt Fog Testing of LED Board
Front side
Back side
Method: ASTM B117-9 for 168 hours
Parylene coated LEDs showed no corrosion, while corrosion was seen on acrylic coated boards.
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Prediction of End of Useful Life
Parylene Types
150oC 135oC 80oC
Parylene HT ~ 40 yrs. ~ 100 yrs. >100 yrs.
Parylene C ~ 24 hours ~ 70 hours ~ 10 yrs.
1
10
100
1000
10000
100000
1000000
10000000
1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3
Log Time to Failure (h
rs)
103/T Ko
Arrhenius Plot: Parylene HT vs. Parylene CLog Time to Failure vs. Reciprocal Absolute Temperature
(Failure: reduced elongation and tensile strength)
150oC
80oC
49
6o C
44
1o C
39
4o C
35
2o C
31
5o C
28
2o C
25
3o C
22
7o C
20
3o C
18
1o C
16
2o C
14
4o C
12
7o C
11
1o C
97
o C
84
o C
72
o C
60
o C
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Practical IssuesParylene as a Barrier
• Quality and type of substrate• Substrate preparation• Masking and adhesion promotion• Fixturing• Handling
Failed assembly with spots of poor adhesion
Good assembly withgood adhesion (no spots)
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Adhesion Challenges
Corrosion of a PCBDelamination, chipping
Blister
Delamination with corrosion
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Coating adhesion failure leading to delamination and/or corrosion
No clean flux residue and corrosion on a PCB
Adhesion Challenges
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Developments in Adhesion Promotion Technologies
AdPro Plus & AdPro Poly are trademarks and service marks of Specialty Coating Systems, Inc.
Chemical compounds applied to a variety of polymeric substrates (e.g., polyimide, epoxy, acrylic, EPDM, etc.) as a tie layer prior to the
application of Parylene coating.
AdPro Poly®
Chemical compounds applied to a variety of metallic and plastic substrates (e.g., Stainless Steel, Cobalt-Chromium, Copper, Gold,
Iridium, Nitinol, Platinum, Solder, Tin, Titanium, Tungsten, Aluminum, Nickel, Chromium, Brass, Polycarbonate, etc.) as a tie
layer prior to the application of Parylene coating.
AdPro Plus®
AdPro Plus and AdPro Poly are registered trademarks of Specialty Coating Systems, Inc.
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Adhesion Systems
Silane A-174 commonly used adhesion
promotion system
AdPro Plus®
AdPro Poly®
Substrates
Metallic substrates•Stainless Steel, Cobalt Chromium,
Copper, Gold, Iridium, Nitinol, Platinum, Silver, Solder, Tin, Titanium, Tungsten, Aluminum, Nickel, Chromium and Brass.
Plastic Substrates•Polycarbonate, COP, COC, Polyester,
Acrylic, Epoxy, Silicone Rubber, PEEK, Santoprene, Styrene Butadiene, Bakelite, Polyamide and Polyimide.
Evaluation of Adhesion Systems
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
• Biocompatibility Testing– Parylene C coating using AdPro Plus and AdPro Poly– Per ISO-10993
• Thermal Humidity Aging Resistance– Parylene C & Parylene HT using AdPro Plus– FED STD 141, Method 4061 (Referenced in MIL-I-46058C)
• Insulation Resistance– Parylene C & Parylene HT using AdPro Plus – In accordance with MIL STD 202, Method 302
• Adhesion Testing - ASTM D 3359
– Test conditions:• 50% RH, after 24 & 48 hrs• Autoclave 125oC for 1 hr
Evaluation of Adhesion Technology
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Adhesion Test Results
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Adhesion Promotion Technologies
DuPont™ and Kapton® are trademarks or registered trademarks of E.I. du Pont de Nemours and Company.
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Qualified Product List - Mil Spec
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Advanced Parylene Applications
Image courtesy of Dr. Y. C. Tai, Caltech.
Parylene check valveParylene platinum retinal implant electrodes
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Advanced Parylene Applications
Check valve
Electrolysis pumpIn-channel check valve
Parylene channelMicro pump
Reaction chamber or reservoir
100 mMicro Active Valve
Thermal Flow
Sensor
Images courtesy of Dr. Y. C. Tai, Caltech.
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
10 and 30 micron silicon vias
Parylene Etching
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Parylene Etching
Anisotropic profile of 55 µ Parylene
Anisotropic profile of 10 µ Parylene
ICP etch recipes for low temperature (5ºC) Parylene etching
Reference: A HIGH ASPECT RATIO, FLEXIBLE, TRANSPARENT AND LOW-COST PARYLENE-C SHADOW MASK TECHNOLOGY FOR MICROPATTERNING APPLICATIONSBy: S. Selvarasah1, S. H. Chao, C.-L. Chen, D. Mao, J. Hopwood, S. Ryley, S. Sridhar, A. Khademhosseini, A. Busnaina, and M. R. Dokmeci, Shadow Mask Transducers 2007
Etching Method ParylenePlasma (200 mT, 400W) 0.19 µm/min
RIE (100 sccm, 200mT, 400W) 0.56µm/min
DRIE (60 sccm, 23mT, 800W) 0.77µm/min
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
ConclusionParylene Technology for Electronics
Parylene N, C and Parylene HT® are suitable and capable of meeting the growing reliability & protection requirements of electronics packaging.
Parylene HT has additional advantages:
• Exceptional thermal stability in air and inert atmosphere
• Improved electrical properties
• Excellent crevice penetration
• Low coefficient of friction
• UV stability
• Resistance to solvents, corrosive chemicals and gases
CTEA (Central Texas Electronics Association), Electronics Design & Manufacturing Symposium , Tuesday, February 5, 2013
Parylene Technology for Electronics
John SterrettTerritory ManagerE [email protected] 214.383.3600F 214.292.9722
Rakesh Kumar, Ph. D.VP of TechnologyE [email protected] 317.244.1200 x 266F 317.472.1215
Contact InformationAlan HardyAutomotive, Electronics &Military Market ManagerE [email protected] 317.244.1200 x 261F 317.472.1215