EEA Grants Norway Grants Ing. Marcela Králová Ph.D., CEITEC Comparison of three common deposition techniques:  Spin-coating  Dip-coating  Material printing

Principle of spin-coating Principle of dip-coating Different technique of material printing Advantage and disadvantage of material printing Applications Content

Principle: Substrate is coated by ink Substrate is rotated (majority of the ink is flung off the side) Drying the substrate by airflow Creation of desired layers Principle of spin-coating

Parameters: Thickness: nm – m Speed: more than 600 RPM (10 rotations per second) Ink: photoresist, insulator, organic, inorganic material Advantages: Quickly and easily produce uniform film Coating of small (mm) or large substrate (dm) Disadvantages: Low usage of materials (10%) Principle of spin-coating

Principle: Dip a substrate into dip coating liquid Wait for a liquid surface to become the stationary state Raise the substrate up perpendicularly Control film thickness Principle of dip-coating

Parameters: Thickness increases with withdrawal speed Depends on viscosity, density and surface tension of liquid Advantages: Easy and simple maintenance Lower loss of coat liquid than in spin-coating Disadvantages: Deposition of both sides Precise control and clean environment Principle of dip-coating

Material printing Classical Digital Offset Gravure Screen Electro- graphy Electro- graphy Ink-jet Relief

Principle: Applying dampening solutin on the printing plate Applying ink on the printing plate Ink transfer from printing plate to the blanket cylinder Ink transfer from blanket cylinder to substrate Offset printing

Printing plate (printing and non-printing areas in same level) Printing areas – hydrophobic Non-printing areas – hydrophilic Dampening solution – water + additives Offset printing

Ink transfer is affected by: The thickness of ink layer on the printing plate The period of contact (printing speed and geometry of the printing components) The printing pressure The rheological properties of ink The temperature (on rheological properties) The surface properties (wettability, absorbency, roughness…) Offset printing

possible construction Three transfer cylinders Possible reverse printing Three cylinder units Diameter of impression cylinder is same with others

Offset printing possible construction One transfer cylinder Impossible reverse printing Three cylinder units Diameter of impression cylinder 2x than the other

Offset printing possible construction One transfer cylinder Impossible reverse printing Five cylinder units Diameter of impression cylinder 4x than the other

Principle: Printing plate is inked and flooded with ink Ink is removed by a wiper of blade Transport of ink onto the substrate Image elements are engraved into the surface of the cylinder Non-image areas – at constant level High printing pressure Adhesive forces between printing substrate and ink Gravure printing

Ink transfer is affected by: The wetting properties of the printing substrate The surface properties of the materials involved The properties of the substrate The viscosity of the ink The printing pressure The printing speed The shape of the cells and their filling level Gravure printing

Principle: Printing elements are coated with ink (constant thickness) Transfer ink onto the substrate Printing elements are raised above the non printing elements Book printing Flexographic printing Letterset Relief - Letterpress

Ink transfer is affected by: The thickness of ink layer on the printing plate The period of contact (printing speed and geometry of the printing components) The printing pressure The rheological properties of ink The temperature (on rheological properties) The surface properties (wettability, absorbency, roughness…) Relief - Letterpress

The oldest printing technique (Gutenberg) Two cylinders system and direct printing (unreadable text) Raised printing elements (40 – 400 m; selectivity of ink transfer) Plate is hard and uncompressible High pressure (MPa) Highly viscous, pasty ink Smooth substrate Letterpress - Book printing

Letterpress – Book printing

Disadvantage (comparison with offset) Expensive printing plate Costly preparation of the printing plate Limited print quality Limit of production speed Letterpress – Book printing

Operation for the creating of printing plate Removal of the protective film Exposure through a negative film Washing of non-crosslinking photopolymer Drying of print relief Complete polymerization of the print relief Letterpress – Book printing

Known from 1950 (previously as aniline printing) Soft, flexible elements Low pressure Ink with low viscosity (possible to print on a wide range of absorbent and non-absorbent substrates) Substrate (rough surface) Letterpress – flexographic printing

Principle: Ink transfer to anilox roller Ink transfer from anilox roller to printing plate Ink transfer onto the substrate Letterpress – flexographic printing

Disadvantage (comparison with offset): Quality is lower 48 lines/cm (flexography) lines/cm (offset) Letterpress – flexographic printing offset flexography

Principle: Ink transferred to an intermediate cylinder covered with the blanket Ink transfer from intermediate cylinder to substrate Indirect process as well as offset Letterpress – lettreset

Push-through process (special type of stencil printing) Stencil is fastened onto the surface Ink can be applied with a brush or squeegee with a spraygun or an airbrush Different substrates and inks Disadvantage: Part must to be connected Screen printing

Spread of ink by a squeegee (without pressure) Ink is pressed through the plate with a higher pressure Separation of plate and substrate Ink is drawn out of the screen mesh Applications (artistic, large-scale,…) 3 methods: Flat to flat Flat to round Round to round Screen printing

Flat to flat: Flat printing plate Flat printing substrate

Screen printing Flat to round: Flat printing plate Round printing substrate Printing plate and impression cylinder move in one direction Printing on cans, balls…

Screen printing Round to round: Round printing plate Round substrate Synchronized movement

Non-impact printing technology Ink is sprayed from nozzle Imaging is done directly onto the substrate Characteristics: Droplet volume: 2–160 pL Spatial frequency of droplets adjusting: dpi Temporal frequency of droplets formation: dozens – hundred kHz Printing of whole surface: Stationary nozzles and substrate movement Nozzle movement across the substrate and simultaneously substrate movement Ink-jet printing

Ink-jet printing - inks

Binary deflection (two charges) Uncharged droplets (reach the paper paper) Charged drops(deflected and fed to a collection device ) Drop size and interval depend on: Nozzle diameter Viscosity and surface tension of ink Frequency of excitation The quality depends on: Quality and continuity of drop stream Parameters: Frequency (1 MHz) Drop size (4 pL) Drop diameter (20 L) Drop speed (40 m/s) Ink-jet printing-continuous

Multi deflection (different charge) Different intensity of charge – different deflection Jet can be deflected in 16 positions Height of tha written line depends on the distance between ink jet head and the paper surface Resolution is reduced with increasing writting height Resolution is determined by Speed of the substrate Drop frequency Maximum resolution is 7 x 6 dots (h x w) Ink-jet printing-continuous

Thermal ink-jet process (bubble jet) Ink-jet printing-drop on demand

Time sequence for drop formation

Thermal ink-jet process (bubble jet) Parameters: Drop volume: 23 pL Drop diameter: 35 m Drop frequency: 5-8 kHz Resulition: 600 dpi Ink-jet printing-drop on demand

Piezo ink-jet process (mechanical displacement) Ink-jet printing-drop on demand

Rear wall Channel wall

Electrostatic ink-jet process Ink-jet printing-drop on demand

Drop formation Drop generation

Comparison SpinDipInkjet Precursor use efficiency  95% wasted  5% wasted Coated areacmdm (m) Sensitivity to surface defects high low Possibility of patterningnone unlimited

Office printer Since 2005: Epson printers Modified CD holder Experimental printer Since 2009: Inkjet deposition printer Fujifilm Dimatix Applications

Example of printed structure Photocatalysts layers  patterns Sensors electrodes + active layers Solar cells Applications

Liquid precursor Substrate: glass or pyrex plates Applications - office printer

Liquid precursor Substrate: glass, pyrex plates, foils, Applications - experimental printer

Thank you for your attention This project is funded by the Norwegian Financial Mechanism. Registration number: NF-CZ07-ICP Name of the project: „Formation of research surrounding for young researchers in the field of advanced materials for catalysis and bioapplications“