1. Advanced Electronic Materials II (GIG 742)
Lecture materials in pdf format: http://mse.korea.ac.kr/efml/lec-aem2.htm
Professor : Jong-Heun Lee
Engineering building, Room No. 208, TEL: 3290-3282, jongheun@korea.ac.kr
< Course Description and Objective > ]
Offer the fundamentals of ceramic processing which is related to the fabrication of representative
passive RLC components and their modules such as MLCC (Multi-Layer Ceramic Capacitor),
LTCC (Low Temperature Cofired Ceramics), chip resistor, and chip inductor. The course covers the
ceramic processing issues before sintering, which includes 1) the preparation of ceramic powder and
its characterization, 2) slurry formulation, 3) basic rheology, 4) tape casting, 5) electroding, and 6)
lamination of green sheets. Special focus will be placed upon the fabrication of electronic ceramic
components via tape casting process.
< References >
1. D. J. Shanefield, quot;Organic Additives and Ceramic Processing,quot; Kulwer (1995)
2. P. C. Hiemenz, โPrinciples of colloid and surface chemistry,โ Dekker (1986)
3. ็คพๅๆณไบบ ๆฅๆฌ็ชฏๆฅญๅๆ, Ceramic processing: Powder preparation and forming (1984)
4. ้ฝ่ค่็พฉ, โใใกใคใณใปใฉใใฏในใฎๆๅฝขใจๆๆฉๆๆ,โ
5. G. Y. Onoda, quot;Ceramic Processing Before Firing,quot; John Wiley & Sons (1978)
6. J. S. Reed, quot;Principle of Ceramics Processing,quot; John Wiley & Sons (1995)
<Grading>
final exam (50%) term paper (20%), report (10%), course attendance (20%)
Advanced Electronic Ceramics I (2004)
Coverage of the lecture
1. The review of the powder preparations
(Focus was placed upon the electroceramics powder)
(target): preparation of fine, high-purity, less-agglomerated powder
2. Study the fundamental of the powder dispersion in liquid
- The basics of the colloid chemistry
(electric double layer, Zeta potential, DLVO theory)
- Electrostatic and Steric stabilization of colloid
3. The slurry formation for the tape casting
- The understanding of the organic binder, plasticizer, solvent, dispersant
- The formulation of above constituents for the good dispersion
4. The processing issues related with the mass production of passive
components. (ball milling, deairing, tape casting, drying, electroding
screen printing, alignment, punching, cutting, and lamination)
Advanced Electronic Ceramics I (2004)
2. Syllabus
1. Overview
2. Powder preparation 1: solid state reaction
3. Powder preparation 2: precipitation
4. Powder preparation 3: other methods
5. Powder characterization 1: particle size
6. Powder characterization 2: BET equation
7. Mixing and Milling
8. Compaction
9. Dispersion of Powder in Liquid 1: Electric Double Layer
10. Dispersion of Powder in Liquid 2: Gouy-Chapmann Theory
11. Dispersion of Powder in Liquid 3: Zeta Potential
12. Dispersion of Powder in Liquid 4 : DLVO theory
13. MLCC: general
14. Slurry Preparation and Slip Casting 1
15. Slurry Preparation and Slip Casting 2: Viscosity
16. Tape Casting 1
17. Tape Casting 2
18. Tape Casting 3: Applications 1
19. Tape Casting 4: Applications 2
20. Screen Printing
21. Chip resistor
22. LTCC1
23. LTCC2
24. Chip inductor and Chip varistor
Advanced Electronic Ceramics I (2004)
Important powder characteristics in electroceramics
Starting point 1 :
- The fabrication of ceramic body with a high melting temperature(Tm)
using the sintering process at a low temperature(0.7 ~ 0.9Tm)
- requires the finer particles for the lower sintering temperature
Starting Point 2 :
- The high-purity powder preparation for the well-designed the
electronic properties.
- requires high-purity source materials and wet-chemical process
Starting Point 3 : (in the view of electroceramics by mass production)
- The preparation of well-dispersed slurry with a high solid loading
(using a minimum binder, plasticizer, solvent, and dispersent)
- results optimum particle size (1~0.1ยตm)
Advanced Electronic Ceramics I (2004)
3. Why Fine Powder? To reduce sintering temperature
- full density at
- maximize the driving force for the sintering
1000oC
(excess free energy of surface)
( ~ 0.42 Tm)
- reduce the sintering temperature
- provide fast densification kinetics (Herringโs scaling law: t2 =ฮปn t1)
Ex) CeO2
- at high temperature
4CeO2 โ 2Ce2O3 + O2 (g)
: retard the densification
- Low-temperature sintering
Aggregate
is desirable!
problem
J. -G. Li, T. Ikegami, J. -H. Lee, T. Mori, Acta mater. 49, 419-426 (2001)
Advanced Electronic Ceramics I (2004)
What is good powder?
1. Fine
2. High purity
3. Narrow particle size distribution
4. Homogeneous composition
5. Small agglomeration between primarily particles
6. Good flowability (for better compaction and screen
printing)
7. Stability against atmosphere
8. Spherical morphology
Advanced Electronic Ceramics I (2004)
4. Design of particle size for electronic ceramics (tape casting)
For tape casting, the powder should be dispersed in a liquid slurry homogeneously.
10-3 10-6 10-9 10-10(m)
ยตm
mm nm ร
Micro regime Nano regime
Driving force for sintering
Utilization of the surface and interfacial properties
Easy to achieve dispersion Our challenge
Weak interaction Dispersion Dispersion Severe interaction
between particles (current) (future) between particles
0.5 -10 ยตm 30-500 nm (Van der Waals)
1-5 m2/g 5-100 m2/g
Advanced Electronic Ceramics I (2004)
Multi Layer Ceramic Capacitor: Why Fine Powder 2? downsizing
A
C = ฮต 0ฮต r For high C in small volume
d nโ, t โ (1005โ 0603 โ 0402)
the particle size โ
C: Capacitance
n: number of layer
improvement in
ฮต0 : permittivity in vacuum
the dispersion technology
ฮตr : dielectric constant
improved cutting, aligning,
A: area
t: thickness electroding
Advanced Electronic Ceramics I (2004)
6. Chip resistor
1. Small size
2. No lead (surface-mount type) :
Minimize lead inductance
3. Trimmable
http://www.sem.samsung.co.kr/
Advanced Electronic Ceramics I (2004)
Multilayer chip varistor
VBR = nVg = DVg/d
small D
low VBR(<10V)
D: Thickness between electrode
Vg: macroscopic breakdown
voltage per intergranular barrier
d: grain size
handheld and portable sets
for mobile telecommunications
A. Lagrange, Electronic Ceramics, Chapter 1, edited by B.C.H.Steele
Advanced Electronic Ceramics I (2004)
7. Multilayer chip varistor: Low breakdown operation
Advanced Electronic Ceramics I (2004)
LTCC: Low Temperature Co-fired Ceramics
Low temperature sintering : ~ 850oC
Employ the Ag electrode
http://www.murata.com/murata/murata.nsf/pages/multilayer/
Advanced Electronic Ceramics I (2004)
9. Bluetooth
What is Bluetooth? New communication standard for wireless connectivity.
Why the name Bluetooth? Bluetooth was named after 10th Century Danish King
Harold Bluetooth. King Harold was credited with uniting the provinces of
Denmark under a single crown. Bluetooth technology is suppose to unite all
different digital devices under a single standard of connection.
Advanced Electronic Ceramics I (2004)
Bluetooth
Bluetooth is a global de facto
standard for wireless
connectivity. Based on a low-
cost, short-range radio link,
Bluetooth cuts the cords that (Potential Applications)
used to tie up digital devices. โฆ Laptop PC, PDA
โฆ Cordless Phone
When two Bluetooth equipped
โฆ Cellular/Digital Handsets
devices come within 10 meters
โฆ Wireless Headsets
range of each other, they can
establish a connection together. โฆ WLAN (Wireless Local Area Network)
And because Bluetooth utilizes a Cards
radio-based link, it doesn't
โฆ Digital Camera
require a line-of-sight connection
โฆ WAN Devices (Wide Area Networks)
in order to communicate.
โฆ PAN Devices (Personal Area Networks)
โฆ Wireless Barcode Scanners
Your laptop could send
information to a printer in the โฆ Wireless PC Accessories
next room, or your microwave (Printers, Mouse, keyboard, etc)
could send a message to your
mobile phone telling you that
your meal is ready.
From www.nokia.com
Advanced Electronic Ceramics I (2004)
10. SOFC(Solid Oxide Fuel Cell)
High ratio of energy conversion (~60%)
Power-generation module
(Breakthrough) Preparation of
Defect-free & wide-area 8YSZ sheet
Anode supported cell
from the brochure of InDEC B.V.
Expanded view of SOFC
from http://www.spice.or.jp/~fisher/sofc.html
Advanced Electronic Ceramics I (2004)
Powder Powder
Preparation Characterization
Dispersion of
Powder
Slurry
Formulation
Applications Tape Casting
- MLCC
Electroding
- LTCC
Lamination
- Chip R, L, C
- SOFC
Advanced Electronic Ceramics I (2004)