Recent Advances in Anisotropic Conductive Adhesives (ACAs

57 Pages·2013·5.07 MB·English

Recent Advances in
Anisotropic Conductive Adhesives
(ACAs) Technology:
Materials and Processing
Kyung W. Paik
Korea Advanced Institute of Sci. and Tech.(KAIST)
Dept. of Materials Science & Engineering
Nano Packaging & Interconnect Lab.
IEEE CPMT Orange Chapter
6/4/2013
Nano Packaging & Interconnect Lab.
B-Stage Polymer Films Research at KAIST NPIL Lab.
Market
Perio
Technology Features Applications Size Remark
ds
(M$)
1. ACF Thermo-
-Licensed to H&S
(Anisotropic curable - Flat Panel Display 1997 Hightech
Conductive resin+metal assembly (COG, ~2007
(35 Million $/2012)
Film) conductive ball COF, FOG, FOB )
- Camera module
- Touch screen
1-1. Solder ACF Polymer Resin 1000 2008 -Funded by Nokia
panel
+solder ball (203) ~2013 -Engineering sample
- connector
replacement (FOB,
FOF) -2011 Licensed to
1-2. Nanofiber
Polymer Resin
- Fine pitch 2010 OptoPac Co.
ACF +nanofiber
interconnect ~2013 - For COG & Nokia FOF
conductive ball
ACFs
- wafer level process
Polymer Resin -3D TSV wafer-
2009 developing with SEC
2. 3D-TSV NCF for 3D-chip wafer, chip-wafer 65
~2013 -NCFs developed with
stacking stacking
KCC
Polymer Resin
3. Metal - Electrical
+vertically 2012
Nanowire/Polymer interconnection 380 Funded by KOLON
aligned metal ~2013
Composite film - TIM
nanowire
Polymer Resin
4. Graphene/
-Gas barrier film
+electrically 2012 Funded by Korean
Polymer -EMI shielding film 700
aligned ~2013 government
-TIM
Contents
§ New ACF Processing
§ Ultrasonic(US) bonding (vs. thermocompression bonding)
§ Flex on Board (FOB) and Flex on Flex (FOF) combined with
Solder ACFs – fast and reliable
§ Touch Screen Panel (TSP) applications – fast and no thermal damage
§ Wafer-level ACFs Process
§ 3D TSV NCF Vertical Interconnection
§ New ACA Materials
§ Nanofiber ACF materials for fine pitch applications
§ < 20 um ultra fine pitch for COG and COF
§ < 100 um fine pitch for FOF
§ Solder ACF materials combined with US bonding - High current
handling and excellent reliability
§ Summary
Nano Packaging & Interconnect Lab.
Anisotropic Conductive Films (ACFs)
§ ACF = Thermosetting epoxy resin film + Conductive particles
Heat Pressure
Chip or substrate 1
Chip or substrate 1
ACF
ACF
Substrate 2 Substrate 2
Thermal curing
§ Applications of ACFs bonding
Chip-On-Board Flex-On-Board (FOB) Chip-On-Glass (COG) Chip-On-Flex (COF)
Flex-On-Glass (FOG)
Nano Packaging & Interconnect Lab.
ACFs bonding – Thermocompression vs. Ultrasonic Bonding
T/C ACFs U/S ACFs
bonding bonding
Patented
Heating tool U/S horn
Heat
Chip or substrate 1 Chip or substrate 1
Heat coAnCdFuction Local heat generation
Substrate 2 Substrate 2
U/S horn (R.T.) à
Heating tool (250℃~350℃)
ACF (> 250℃)
àACF (180℃)
Nano Packaging & Interconnect Lab.
New U/S ACFs Bonding Mechanism
Due to the loss modulus of ACFs,
ACFs generate spontaneous heat
under vertical ultrasonic vibration
f : Vibration frequency
f (Dε)2 E’’
Heat = Dε: Strain at the ACF layer
2
E’’: loss modulus of the ACF
ACF temperatures can be controlled by Dε
ACF temperatures can be controlled by Dε.

Relative
300
U/S vibration
10%
)
C 250 20%
o
( 30%

e
r 200 40%
u 50%
t
a 60%
r 150
p

e
m
100
e
t

F
C 50
A
0
0 2 4 6 8
Bonding time (sec)
nKorea patent issued 10-0746330
nInternational Patent pending PCT/KR2006/004912
ACF actual temperature profiles of FOB
nJapan, Taiwan, China, Germany patent pending
Nano Packaging & Interconnect Lab.
Commercial U/S bonding machine by MicroPACK Co.
MPB-U110 : 1 head, 1 stage, manual alignment
U/S controller
Main controller
Vision system
U/S part
Stage
Nano Packaging & Interconnect Lab.
Advantages of U/S vs. T/C ACF bonding
1. Reduced Assembly Times & Cost
• Faster ACFs bonding times of U/S
• Epoxy ACFs: 3 ~ 5 sec. vs. 7 ~ 15 sec.
• Acrylic ACFs: 1 ~ 3 sec vs. 5 ~ 7 sec.
2. Reduced thermal damage on boards
• T/C bonding induces thermal damages to boards
• No thermal damages by U/S
• No bonding tool heating
• Very effective on FOB (organic PCBs) such as Touch Screen
Panel (TSP) and thermally sensitive special devices assembly
3. Eco-Processing
• Significant energy saving
• Very little U/S loading cycle
• No idling energy loss – digital control
Nano Packaging & Interconnect Lab.
Nano Packaging and Interconnect Lab.
Potential applications of U/S bonding method
§ Module interconnections
§ Touch screen panels
(Flex-on-Board, Flex-on-Glass)
(PET panel)
§ Semiconductor packaging
ACF
Bonding area (Flip Chip-on-Board) (Chip-on-Flex)
(RF-ID)
Nano Packaging & Interconnect Lab.