1. Screen Printing
The flow behavior of thick film ink
depends on (1) the viscosity and
(2) surface tension
τ (shear stress) P/A
η= =
S(shear rate) V/t
From P.J.Holmes and R.G.Loasby, “Handbook of thick film technology,”
Advanced Electronic Ceramics I (2004)
Screen Printer
Semi-automatic Manual
http://www.bando.net/
Advanced Electronic Ceramics I (2004)

2. Screen Printer
http://www.ahnsclub.com/jejojangbi/jangbi/M-printer3.jpg
Advanced Electronic Ceramics I (2004)
Screen Printing: Principle
Utilize shear thinning at the high stress
during the screen printing process
- the shear rate(viscosity) decreases after
stress
screen printing
Pseudoplastic
Shear rate
From P.J.Holmes and R.G.Loasby, “Handbook of thick film technology,”
Advanced Electronic Ceramics I (2004)

3. Screen Printing: Schematic
From P.J.Holmes and R.G.Loasby, “Handbook of thick film technology,”
Advanced Electronic Ceramics I (2004)
Screen Printing: Variables
1. Screen variable 2. Machine variable
a. Mesh material a. Squeegee attack angle
b. Mesh count b. Squeegee hardness
c. Mesh filament diameter c. Squeegee edge shape
d. Mesh weave d. Squeegee down pressure
e. Mesh tension e. Squeegee traverse speed
f. Mesh filament direction f. snap-off setting
g. Emulsion type g. Flood blade setting
h. Emulsion thickness h. Parallelism of squeegee/screen
I. Pattern direction /substrate assembly
I. Volume of the ink on the screen
From P.J.Holmes and R.G.Loasby, “Handbook of thick film technology,”
Advanced Electronic Ceramics I (2004)

4. Screen Mesh Dimension and Wet Print Thickness
Mesh Type Mesh Count Filament Open Typical Wet
(per inch) Diameter Area(%) Print Thickness
(µm) (µm)
Stainless Steel 150 50 45 57-117
Stainless Steel 165 50 41 50-116
Stainless Steel 200 50 36 45-115
Stainless Steel 200 40 46 45-92
Stainless Steel 325 27.5 41 27-62
Nylon 150 47.5 52 50-87
Nylon 230 35 47 32-75
Nylon 280 30 46 27-55
Nylon 330 30 37 25-50
Typical wet print thickness(t) : 1~2 times of filament diameter.
t decrease as increasing Mesh count & open area(%).
From P.J.Holmes and R.G.Loasby, “Handbook of thick film technology,”
Advanced Electronic Ceramics I (2004)
Typical Specification for Screen Mesh
1. Thickness of mesh: 2-~2.5 times of the filament diameter
2. Open area : 35 ~47%
http://www.wovenwire.com/finemesh-print.htm
Advanced Electronic Ceramics I (2004)

5. Terminology
Plain weave Twill weave
- most widely used
- can accommodate high flow rates
with a relatively low pressure drop
Advanced Electronic Ceramics I (2004)
Composition of Ink vehicle
1. Binder : viscosity control
2. Surface active agent : dispersion of the solid particles and adequate
wetting of the substrate
3. Flow control agent : restrict ink flow during drying
(ex.)
Butyl carbitol acetate (Solvent) 69.12%
Ethyl cellulose (Resin) 14.4%
2-Furoic acid (Flow control agent) 6.4%
Nonyl phenoxypolyoxyethylene ethanol (Surfactant) 10%
Advanced Electronic Ceramics I (2004)

6. Squeegee
Materials
♦ Polyurethane excellent print quality, highly durable
♦ Metal large pressure window than the polyurethane
♦ Composite
Hardness
- Soft squeegee low mesh, low viscosity
- Medium squeegee wide range of mesh
- Hard squeegee high squeegee pressure, high viscosity
Configuration
Advanced Electronic Ceramics I (2004)
Metal pastes for the electronic industry
Application Conductive Resistive Application Conductive Resistive
materials materials materials materials
Hybrid IC Ag/Pd RuO2 Tantalum Ag
Ag/Pt Ag/Pd resistive Capacitor Ag/Cu
Network Ag Au Thick Film Au
resistor Cu High TCR resistive Thermal MOD/Au RuO2 resistive
Au Printer Ag/Pd
Chip resistor Ag RuO2 Head Ag/Pt
Ag/Pd Ag/Pd resistive Ag
Sensors Pt Panel Display Ag RuO2 resistive
Au Au
MLCC Ag MOD/Au
Pd Piezoelectric Ag
Ag/Pd Ceramic
Ni Thermistor Ag/Pd
Cu Varistor Ag/Pt
Heater Ag/Pd Ag/Pd resistive
From http://www.tkg-products.com/
Advanced Electronic Ceramics I (2004)

7. Electroluminescent Lamp
ITO sputtered polyester
(ITO: lamp’s outer electrode)
Bus Bar (Ag, to achieve
maximum current to the coating
Phosphor
(light emitting layer)
Barium titanate
(dielectric insulator)
Rear electrode
(Ag or conductive carbon ink)
Advanced Electronic Ceramics I (2004)
Characteristics of EL
Principle: the rapid charge and discharge of phosphor by applying
AC current result in the emission of light
DCD
- Flexible and thin
C
- minimal heat(cold light source)
- small power consumption (including the inverter efficiency)
(AC 100 ~ 220 V usually used)
(In the case of DC battery system, the inverter is required)
- easy to replace
- easy to fabricate the large-area display
- weak to moisture
(applications)
- back-lightning LCD displays
- control panel
- advertising display
Advanced Electronic Ceramics I (2004)

8. Applications
Fig.: Selective printing of EL lamp areas
Printing all components of EL lamps is especially
Fig. The phosphors used in EL lamps will emit
useful when the switch design calls for small-area
either green, blue, or yellow light. White light
lighting of individual keys. By printing a separate
can also be generated by mixing phosphors or
lamp area for each key, you'll minimize ink
adding dyes
consumption and keep the lamp from drawing
excessive power.
Lighting watch faces Flexible lamp
http://www.screenweb.com/industrial/cont/el_lamps990128.html
Advanced Electronic Ceramics I (2004)