Liquid Crystal Polymer Substrates to Enable
Advanced RF and Medical Applications
Susan Bagen & Brian Sinclair – MST Inc.
Eckardt Bihler, Marc Hauer & Daniel Schulze – DYCONEX AG
New England 42nd Symposium & Expo
LCP – LIQUID CRYSTAL POLYMER - PROPERTIES
SIGNAL ATTENUATION
 Very flexible thermoplastic
5
4.5
 High temperature stability
4
(Tg > 280°C, Td > 320°C)
Near-hermetic
3.5
Attenuation dB
 Very low water absorption (0.04 %)
Si**
3
GaAS**
2.5
2
LCP*
1.5
 Excellent high frequency properties
(εR= 2.9, tan θ = 0.0025)
 Light weight (1.4
g/cm3)
1
0.5
0
0
20
40
60
80
100
120
Frequency GHz
*D. Thompson, et al.,“W-Band Characterization of Finite Ground Coplanar Transmission Lines on Liquid Crystal Polymer (LCP) Substrates”, IEEE ECTC 2003.
** Fred Brauchler, Ph.D. Dissertation, The University of Michigan, Ann Arbor, MI.
New England 42nd Symposium & Expo
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COMPARISON of MATERIALS
Material
Property
LCP
PTFE / Glass
Rogers
Ultralam 3000
Rogers
RT/duroid 5880
Hydrocarbon /
Ceramic
PTFE /
Ceramic
Rogers
RO3003
Different
Suppliers
Rogers
RO4350B
LTCC
Dielectric
constant
@ 10
GHz
2.9
2.2
3.66
3.00
7.4 – 7.8*
Dissipation
factor
@ 10
GHz
0.0025
0.0009
0.0037
0.0013
0.001
Water
absorption
%
0.04
0.9
0.06
< 0.1
< 0.05
CTE X
ppm/°C
17
31
14
17
6 – 10*
CTE Y
ppm/°C
17
48
16
17
6 – 10*
CTE Z
ppm/°C
150
237
35
24
6 – 10*
Density
g/cm3
1.4
2.2
1.86
2.1
3.2
Thermal
conductivity
W/m°K
0.2
0.22
---
0.65
2.8 – 4.9*
* Values vary depending on LTCC type used
New England 42nd Symposium & Expo
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PROCESS PROPERTIES – LCP vs. LTCC
LCP PCB processes produce improved conductor structures with reduced skin
effect losses at high frequencies.
Edge profile
nearperpendicular
and better
defined.
LCP Copper etched conductor profile
LTCC printed conductor profile
Conductor
edge
roughness
reduced.
65µm traces on LTCC
New England 42nd Symposium & Expo
60µm traces on LCP
© DYCONEX AG
May 2015
4
LCP FREQUENCY – UP TO 110 GHz
LCP has stable dielectric
constant over a very
wide frequency range.
Effective Dielectric Constant
3.5
3
2.5
2
1.5
LCP
1
Multilayer structures have
homogeneous LCP dielectric
throughout cross-section.
0
-0.5
0
20
40
60
80
100
120
Frequency (GHz)
Source: IEEE ECTC 2003 “W-Band Characterization of Finite Ground Coplanar Transmission Lines on Liquid Crystal Polymer (LCP) Substrates”,
Dane Thompson*, Pete Kirby, John Papapolymerou, Manos M. Tentzeris, Georgia Institute of Technology
New England 42nd Symposium & Expo
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LCP vs. CONVENTIONAL PCB MATERIALS
Dielectric Constant Variation with Moisture
LCP, Polyimide, and FR-4 Laminates
4.8
4.5
Dielectric Constant
4.3
FR-4: 50°C Immersion
4.0
FR-4: 23°C, 50%RH
3.8
PI: 50°C Immersion
3.5
PI: 23°C, 50%RH
LCP: 50°C Immersion
3.3
LCP: 23°C, 50%RH
3.0
2.8
2.5
0
2
4
6
8
10
12
LCP dielectric constant
remains stable upon
exposure to moisture.
Frequency, GHz
New England 42nd Symposium & Expo
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LCP vs. CONVENTIONAL PCB MATERIALS
Dissipation Factor Variation with Moisture
LCP, Polyimide, and FR-4 Laminates
0.040
Dissipation Factor
0.035
FR-4: 50°C Immersion
0.030
FR-4: 23°C, 50%RH
0.025
PI: 50°C Immersion
0.020
PI: 23°C, 50%RH
0.015
LCP: 50°C Immersion
0.010
LCP: 23°C, 50%RH
0.005
0.000
0
2
4
6
8
10
12
LCP dissipation factor
remains stable upon
exposure to moisture.
Frequency, GHz
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LCP SUBSTRATE FABRICATION FEATURES
Cavity structures for die
placement and patch
antenna
Flexible antennas,
connectors &
electrodes
Source: D.L. Paul, et al., “Flexible Dual Band LCP Antenna for RFID Applications”, Proceedings of the 2013
International Symposium on Electromagnetic Theory, pp. 973-976.
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LCP SUBSTRATE FABRICATION FEATURES
Wirebondable cavity ledge to
access inner layers without
lossy vias
Air bridges
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LCP SUBSTRATE WITH HEATSINK BASE
• High power density application
• Direct bonding to heat sink
• Operating temperature up to 150°C
• Gold wire bondable surface: ENEPIG
• Buried RF tracks under lid mounting
• Lids mounted to circuit to seal cavities
Metal Lid
Cavity
50 µm LCP
50 µm Bondply
100 µm LCP
Die
LCP
Aluminum Plate
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HF LCP BGA PACKAGE
• Laser blind vias 50 or 75 µm
• Laser vias through 3 layers 75 or 100 µm
• Line / Space: > 25 / 25 µm
• Lid sealing for near-hermetic package
Metal Lid
Cavity
50 µm LCP
50 µm Bondply
100 µm LCP
Die
LCP Soldermask
20 µm
BGA
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BIOCOMPATIBLE SUBSTRATES
New
biocompatible
metal layers
New market
fields
Smaller
feature sizes
Biocompatible
PCBs
Large panel
format
Manufacturing
know how
Long term
stability
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COMPARISON: Standard PCB vs. Noble Metal PCB
Standard PCB subtractive copper etching
Noble metal PCB additive technology
•
•
•
•
•
•
Thick metal
Line / Space: > 25 µm
Reliable z-axes connection (via)
Standard PCB
Thin metal
Line / Space: < 25 µm
Challenging z-axes connection
Noble Metal PCB
Thick Cu
Thin Metal high resolution
Reliable vias
Biocompatible Electrodes
Multilayer
Flexible thin PCB
Typical build up of a sensor
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ISO 10993-1:2009 + Cor 1:2010 Regulation
Definition of Biocompatibility:
“The quality of not having toxic or injurious effects on biological systems.“ *
The ISO 10993-1:2009 + Cor 1: 2010 set a series of standards for evaluating the
biocompatibility of a medical device prior to a clinical study. **
– 18 different specification points
• ISO 10993-1:2009 Biological evaluation of medical devices Part 1: Evaluation and testing in the risk
management process
• ISO 10993-18:2009 Biological evaluation of medical devices Part 18: Chemical characterization of
materials
Project Risk
Wrong constraint
"There is no bio-incompatible material….
…. the dose makes the poison"
Patient Risk
too carefully
too careless
Bio PCB Project
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* Dorland's Medical Dictionary ; ** Wikipedia
01.04.2015
14
ISO 10993-1:2009 + Cor 1:2010 Biological Evaluation Tests
Blood Path
Direct
External Tissue bones
Device
dentin
Circulating
blood
Tissues
bones
Blood
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o
x
o
o
Chronic toxiticity
Carcinogenicity
x
Hemocompabtibility
Subacute and
subchronic toxiticity
x
x
x
x
x
x
x
x
x
x
o
o
x
x
o
x
x
x
o
x
x
o
o
x
x
o
x
x
x
x
x
x
x
o
x
o
x
x
x
x
o
x
x
x
x
x
x
x
x
x
x
o
x
x
x
x
x
x
x
x
x
x
o
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x - Test according ISO 10993-1
o - Additional Tests (USA)
Implantation
Mucosal
menbrane
Breached
surface
Implant
Device
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
Genotoxiticity
Skin
Surface
Device
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
Contact
Systematic Toxiticity
Category
A- limited (< 24 h)
B- short term (24h - 30 d)
C - permanent (> 30 d)
Sensitization
Contact Time
Nature of
Body Contact
Cytoxiticity
• Not all tests are essential but
a base knowledge of ISO
10993 is mandatory
• Substrates processed by
DYCONEX have been
successfully tested for ISO
10993-5 Test for in vitro
cytoxicity
Biological Effect
Irritation or intra
cutaneous reaction
Medical Device Category
o
o
x
x
x
x
o
x
x
x
x
o
x
x
x
x
o
x
x
x
x
x
x
x
x
x
May 2015
o
o
x
x
x
o
15
BIOCOMPATIBLE MATERIAL – AVAILABLE OPTIONS
• For flexible applications:
– Polyimide
– LCP
• For rigid applications:
– Glass
– PEEK
– Flexible material with a rigid stiffener
• Cover materials:
– For flexible applications:
• Solder mask (can be used for short term implants)
• LCP
– Parylene coatings
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APPLICATION: SHORT TERM BLOOD GLUCOSE SENSORS
• Compact, handheld, portable device which
measures blood glucose levels as part of a diabetes
management regimen for the chronic diabetic
• Direct implantable bio sensor with clinical
approved studies
– flexible PCB substrate
– flexible cover mask
• 30 days in human body
• Measures capacitive electric charge current
• Typical 3-electrode system
Counter
Electrode
C
Reference
Electrode
Work
Electrode
Ag/AgCl
Au
New England 42nd Symposium & Expo
Source:
http://diabeteshealth.com/media/images/article
_images/5060.jpg
Source: www.medtronicdiabetes.com
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May 2015
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APPLICATION: PERMANENT IMPLANT COCHLEAR ELECTRODES
• Need of pure biocompatible materials
without copper for long term implant
– LCP for excellent biocompatible properties
– Au for good adhesion and flexible properties
cover mask
Pt
Au
LCP
– Pt for selective electrodes robustness
• Test design with 125 µm traces on 250 µm pads
•
Test structures with 15 µm Line / Space
N =5.62 %
C =2.84 %
Au = 91.54 %
pure gold
electrodes
gold + platinum
electrodes
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APPLICATION: THERMISTORS FOR HEAT MEASUREMENTS
• Balloon catheters with electrodes for
neurostimulation or ablation
•
•
•
Invasive surgical procedure
Extremely flexible ultra thin 2-layer LCP build up
with 50 µm final thickness
One thermistor per electrode couple with thin film
layer
• 25 µm Line / Space
• One sided copper plating with 100% via-fill
Source: http://de.wikipedia.org/wiki/Angioplastie
• Surface finish: electroplated gold on copper
for short term implant
Source: http://www.p-wholesale.com/
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SUMMARY
• Advanced LCP processing has been developed to establish fabrication
capabilities of complex substrates for RF microwave applications
as well as structures for directly implantable medical technologies.
• Examples of RF substrate designs are complex multilayer stackups
that include cavity structures for bonding of high power die directly to
heat sink materials.
• Multilayer structures of LCP with noble metal conductors for
biocompatible medical implants are also discussed.
New England 42nd Symposium & Expo
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THANK YOU FOR YOUR ATTENTION!
DYCONEX AG
Grindelstrasse 40
CH-8303 Bassersdorf
Switzerland
www.mst.com/dyconex
[email protected]
Phone +41 (43) 266 11 00
Fax
+41 (43) 266 11 01
New England 42nd Symposium & Expo
© DYCONEX AG
May 2015
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