Ultrasonic Coating

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Ultrasonic Coating Systems for Solar Cell
Manufacturing
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Our History
Sono-Tek Corporation was founded in 1975by Dr.
Harvey L. Berger, Ph.D. Inventor of the
ultrasonic nozzle
The first ultrasonic nozzles were developed for
use in oil burners and subsequently for the
development of liquid fuel burners contracted by
the U.S. Military for use in portable power
generation equipment. Today Sono-Tek offers a
wide selection of precision ultrasonic coating
systems across various industries including
Energy, Defense, Semiconductor, Aerospace,
Medical Devices, Glass Manufacturing, and
Textiles.
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Common Stock
Sono-Tek became a publicly traded company in
1987. The Companys Common Stock trades in the
over-the-counter market on the OTC Bulletin Board
under the symbol SOTK.
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Corporate Headquarters
Sono-Teks corporate headquarters is located in
Milton, NY, USA. This facility houses our
factory as well as a full staff, including our
engineering, sales, accounting, manufacturing,
quality control, technical support and shipping
departments. Sono-Tek has a satellite office in
Hong Kong to facilitate sales and service to our
Asian customers. We also have laboratory testing
facilities located in the U.S., Germany, Honk
Kong, Korea, and Taiwan.
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Ultrasonic Atomization

• When liquid is added to a resonating nozzle,
  waves are formed on the atomizing surface
• SONO-MATH 101
• ?L((8p?)/(?f2))1/3
• p pi
• ? Surface Tension
• ? Density
• F Frequency of Nozzle

• Increasing the power causes the wave peaks to get
  so high that droplets fall off the tips of the
  wave.
• These droplets have a mathematically definable
  size.
• SONO-MATH 101
• DN, 0.5.34?L
• Notice also that less of the atomizing surface is
  used (for a given flow rate).

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Industry Expertise
FUEL CELL
ELECTRONICS
SOLAR CELL
MEDICAL
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Product Line for Solar Cell Manufacturing

• Thin Film Solar Cells
• Deposition of active layers
• Deposition of buffer and/or organic layers
• Deposition of TCO
• Silicon Solar Cells
• SelectaFlux - Fluxing of Solder Bus on
  Tabber/Stringer machines
• ChemCoat Phosphoric/Boric Doping
• Solar Cell Packing
• 7. Anti-reflection Coatings

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Thin Film Solar Cells Typical Layering of a Thin
Film Cell
Cells may be comprised of some or all of the
following layers, this is a typical cell in a
substrate configuration.

• GLASS/PROTECTIVE LAYER
• ANTI-REFLECTION LAYER
• TCO
• Buffer Layer / PEDOT (OSC)
• ACTIVE LAYER
• BACK CONTACT

Sono-Tek can coat these layers
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Product Line for Solar Cell Manufacturing

• Thin Film Solar Cells
• Deposition of active layers
• Deposition of buffer and/or organic layers
• Deposition of TCO
• Silicon Solar Cells
• SelectaFlux - Fluxing of Solder Bus on
  Tabber/Stringer machines
• ChemCoat Phosphoric/Boric Doping
• Solar Cell Packing
• 7. Anti-reflection Coatings

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Thin Film Solar Cells Active Layer

• The active layer creates the positive side of the
  p-n junction and creates a potential in the thin
  film structure. It contains semiconducting
  materials which may be one of the following
• CIS
• Thickness 1.5 4.5 microns
• CIGS
• Thickness 1.5 - 4.5 microns
• CdTe
• Thickness 2 - 5.5 microns
• CTZS(S)
• Thickness 2 - 5.5 microns
• DSC Thickness 1 3 microns
• Quantum Dots
• Nano-crystal semiconducting dots contain Zn, Pb,
  Cd, Se
• Perovskites
• Thickness 50nm 1 micron

GLASS/PROTECTIVE LAYER ANTI-REFLECTION LAYER TCO
ACTIVE LAYER BACK CONTACT
Buffer Layer / PEDOT (OSC)
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Active Layer Coating EquipmentLow to High Volume
Solutions
RD
Low to Mid Volume Production
High Volume Production
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Thin Film Solar Cells Active Layer

• Alternate deposition methods
• CVD, Sputtering
• Extremely expensive, high initial capital cost
• Batch processing (trending toward inline with new
  systems)
• In many cases low transfer efficiency as low as
  50

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Product Line for Solar Cell Manufacturing

• Thin Film Solar Cells
• Deposition of active layers
• Deposition of buffer and/or organic layers
• Deposition of TCO
• Silicon Solar Cells
• SelectaFlux - Fluxing of Solder Bus on
  Tabber/Stringer machines
• ChemCoat Phosphoric/Boric Doping
• Solar Cell Packing
• 7. Anti-reflection Coatings

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Thin Film Solar Cells Buffer Layer / Use of
Polymers

• CIGS, CDTE, Cells
• Common Buffer Layer
• CdS - Thickness .02 - .05 microns
• ZnS Thickness .02 - .05 microns
• Organic Cells, Perovskite
• Typical Polymers - PCBM, P3HT, P3HD
• PEDOT layer is commonly used with active layers
  made of polymers, and acts as an anode, and is
  currently used in RD applications
• Polymers are often sprayed in inert environment
• Requires very low oxygen levels(lt2 ppm)
• Thickness ( 0.11 0.17 microns)
• Temperature 25 - 75ºC
• Annealed at low temperatures(150 250ºC)

• Mixed with solvents
• Chlorobenzene
• P-Xylene

GLASS/PROTECTIVE LAYER ANTI-REFLECTION LAYER TCO
ACTIVE LAYER BACK CONTACT
Buffer Layer / PEDOT (OSC)
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Thin Film Solar CellsDSC Organic Solar Cells
Layers

• TCO layers can be created with ultrasonic spray
  pyrolysis.
• Cathode layer Platinum is most efficient but
  high , graphite less expensive and less
  efficient.
• Electrolyte usually applied in gel form. Needs
  to be diluted to be sprayed with ultrasonics.
• Dye Usually dip coated but can be applied with
  ultrasonic spray.
• Compact oxide can be sprayed with ultrasonics,
  then heated.
• Glass is often purchased with TCO layer already
  applied.

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Thin Film Solar CellsPerovskite Solar Cells
Layers

• Sono-Tek ultrasonic nozzles can be used to spray
  the following layers
• TCO (CNT, Graphene, Silver Nanowires, ITO FTO
  through spray pyrolysis.
• Perovskite materials.
• HTM (PEDOT PSS, P3HT)
• Nano-Metals (Nano-Gold, Silver Nanowires)

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Thin Film Solar Cells ExactaCoat Inert
Commonly used for Organic Solar Cell
Manufacturing Built for continuous operation with
constant positive pressure environment using
Nitrogen, Argon or Helium

• lt1 ppm H2O and O2 inert gas
• Continuous recirculation and on-line monitoring
  of O2 and moisture content
• Hepa gas flow filters at chamber inlet and outlet
• 36 D x 48 W x 36 H chamber
• Large antechamber - 38 cm (15) OD and mini
  antechamber - 15 cm (6) OD
• 400 mm x 400 mm x 100 mm
• (15.75 x 15.75 x 3.94) XYZ range of motion
• Includes Windows-based (programming) software
  with image import
• Nozzles can be easily interchanged to produce
  varying spray patterns ranging from 0.080 to 3
  (2 - 76 mm) wide

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Product Line for Solar Cell Manufacturing

• Thin Film Solar Cells
• Deposition of active layers
• Deposition of buffer and/or organic layers
• Deposition of TCO
• Silicon Solar Cells
• SelectaFlux - Fluxing of Solder Bus on
  Tabber/Stringer machines
• ChemCoat Phosphoric/Boric Doping
• Solar Cell Packing
• 7. Anti-reflection Coatings

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Thin Film Solar Cells TCO/Contact Grid

• TCO (Transparent Conductive Oxide) consists of
  metals dissolved in solution having high
  conductive and transparent properties. It acts
  as the front contact to the device and is needed
  to reduce the series resistance of the device.
  Sometimes applied at high temperatures in
  pyrolysis reaction. Also, they often require
  high temperature annealing at 500 600 degrees
  C.
• ITO
• Can increase conductivity of ITO in 2 ways
• Increasing heat - Increasing the temperature of
  the substrate during the coating process has
  indicated an increase in conductivity
• Increasing thickness of ITO layer ( 0.04
  microns)
• Problems
• As thickness increases, cracking is more
  susceptible
• ZnO ( 0.2 - 0.5 microns)
• Doped with Ga, Al, In
• Structure and morphological properties same for
  Ga, Al and In
• Optical properties much better for In (smoother)
  than for Ga or Al
• ZnO has the highest piezoactivity compared to
  other TCOs
• CdO
• Doped with In, Sn, F
• F is preferred because of low cost and is less
  hazardous
• SnO2 (Commonly SnO2 F or FTO)

GLASS/PROTECTIVE LAYER ANTI-REFLECTION LAYER TCO
ACTIVE LAYER BACK CONTACT
Buffer Layer / PEDOT (OSC)
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Spray Pyrolysis Applications

• Definition of Spray Prolysis - A process in which
  thin film is deposited by spraying solution onto
  a heated surface, where constituents react to
  form a chemical compound
• One Major Glass Manufacturer 6 million m2/yr
  doing spray pyrolysis on float glass line. 600
  700 degrees C.
• ExactaCoat for TCO Duplicates this process on a
  smaller scale. Can be scaled up to much larger
  process, i.e. float glass line.

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Thin Film Solar Cells ExactaCoat for TCO RD
System

• Fully Enclosed XYZ Motion System for Ultrasonic
  Spray Pyrolysis, depositing TCO layers in RD
  scale spray applications.
• Precise substrate uniformity with repeatability
  down to /-2
• Compact benchtop design that favors portability
• 400 mm x 400 mm x 100 mm (15.75 x 15.75 x
  3.94) range of motion
• PathMaster Windows-based programming software
• Remote trackball teach pendant
• Coordinated motion in all three axes
  simultaneously
• Optional 250oC heat plate or 600oC ready with
  customers plate
• Cooling of ultrasonic nozzle
• Protective bellows and covers over XYZ slides and
  motors
• Cooling of XYZ motors
• Teflon coated wetted surfaces
• Cobalt A12 Series corrosive resistant nozzle
  (typical)

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Thin Film Solar Cells Impact ARRAY Production
Volume TCO System

• Inline spray system with Cobalt A12 Series
  corrosive resistant nozzles.
• Proprietary materials of construction
  protectwetted paths from TCO acid solutions.
• Ability to easily manipulate coating thickness.
• Full process control with recipe storage through
  HMI touch screen PLC interface.
• Integrated control of nozzle, liquid delivery
  flow rate and deposition for a full coating
  solution.
• Non-clogging ultrasonic nozzles produce
  repeatable, controllable, uniform thin films.
• Designed for integration into high volume
  manufacturing lines.
• Cost effective alternative to sputtering or CVD.

Inline Ultrasonic Spray Pyrolysis System
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Thin Film Solar CellTCO Layers

• Alternate deposition methods
• CVD, Sputtering
• Extremely expensive, high initial capital cost
• Batch processing (trending toward inline with new
  systems)
• In many cases low transfer efficiency as low as
  50

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Thin Film Solar Cells CNT and AgNW as Future TCOs

• Why CNT/AgNW would be a desirable material for
  TCO layer
• Ability to be processed at low temperature and
  ambient pressure
• Low cost (for CNT)
• Works well with polymer active layer
• PEDOT
• P3HT/PCBM
• Advantages over ITO (Possible future replacement)
• CNT are capable of being put into liquid solution
  for deposition
• Abundant raw material
• Highly flexible
• Excellent stiction (adherence to substrate and
  reduced friction)
• Visible in infrared range
• Extremely high conductivity

GLASS/PROTECTIVE LAYER ANTI-REFLECTION LAYER TCO
ACTIVE LAYER BACK CONTACT
Buffer Layer / PEDOT (OSC)
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Thin Film Solar Cells CNT Deposition Advantages
Ultrasonic technology brings a large advantage in
the deposition of CNT/AgNW due to the ability to
deagglomerate/ break apart clumped solids.
Ultrasonic action of the nozzle deagglomerates
CNT clumps during the spray process
CNTs deagglomerated with ultrasonic spray
CNTs agglomerated prior to ultrasonics
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Thin Film Solar Cells Manufacturing Market
Competition
Process How it works Disadvantages (to ultrasonic spray) Cost
Sputtering Ejecting particles from a target, by bombardment with high energy particles to a substrate in a straight line. Very expensive, poor transfer efficiency, batch process, and is prone to contamination.
Chemical Vapor Deposition Creates a reaction between various gasses over a substrate which condense on its surface creating a thin solid layer. Expensive to scale up, very high operating expenses, and poor material usage.
Screen Printing Spreading a paste with a blade over a recessed substrate. High load system, requires min viscosity, and poor uniformity on very thin coatings.
Inkjet Printing Operates in a similar fashion to home / office inkjet printer, ejecting tiny drops above a substrate. Uneven surface contours, series of drops/uneven dispense, poor tolerance to abrasive chemicals, and high maintenance.
Spin Coating Solution is placed on substrate and dispersed via a centrifugal force of spinning substrate. Coating thickness is limited as is substrate size, batch process, and it cannot be patterned or scaled up.
Pressure Spray Forces a liquid through a very small orifice to create small droplets. High velocity creates bounce back and wastes material, poor turn down ratio, and large drops. Prone to clogging.
Ultrasonic Spray Drops are formed as a result of wave formation at the atomizing surface. Soft spray has little kinetic energy. Liquid is not constricted through the nozzle orifice. ADVANTAGES Tight drop distribution and non-clogging ultrasonics create very uniform thin films. Independent control of flow rate, drop size and deposition maximizes process efficiency and material usage.
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Product Line for Solar Cell Manufacturing

• Thin Film Solar Cells
• Deposition of active layers
• Deposition of buffer and/or organic layers
• Deposition of TCO
• Silicon Solar Cells
• SelectaFlux - Fluxing of Solder Bus on
  Tabber/Stringer machines
• ChemCoat Phosphoric/Boric Doping
• Solar Cell Packing
• 7. Anti-reflection Coatings

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SelectaFlux for Fluxing Solder Bus Lines

• Fluxing and soldering of the solder bus is a
  crucial process as it ensures that the
  connections between the silicon crystal and the
  conductive electrical contacts are optimal for
  electricity to flow between them properly. This
  process is key to ensuring the modules quality
  and longevity.

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SelectaFlux for Fluxing Solder Bus Lines

• Used in Tabber Stringer Machines for fluxing the
  Solder Bus

SOLDER BUS LINES

• Need to flux both sides of Solder Bus (top and
  bottom)

SOLDER CONNECTIONS TO BUS LINES
(NEGATIVE)
(POSITIVE)

• Typical 2 or 3 Solder Bus lines per solar cell

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SelectaFlux for Fluxing Solder Bus Lines

• Ultrasonic Advantages
• Proven technology in high-volume solar cell
  manufacturing (100s of machines installed)
• Ability to control flux thickness
• Ultrasonic nozzles never clog
• No overspray
• Good edge definition
• Only monthly maintenance
• Simple adjustment of spray width from 2mm 5mm
  by adjusting distance to solar cell
• Non-contact fluxing method
• Spray up and spray down configurations

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SelectaFlux for Fluxing Solder Bus Lines

• Fluxing pads (New method for fluxing solder bus
  lines)
• 7 m/sec line speed typical
• Faster, cheaper method of solder bus fluxing

Flux deposition shown in green
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SelectaFlux for Fluxing Solder Bus Lines

• Fluxing Method Comparison
• Jetting technology

JETTING NOZZLE
ROLLER TECHNOLOGY

• Provides very small jets of flux 0.5mm.
• Spray is NOT atomized, causing excessively thick
  flux layer. This causes excess flux to be
  deposited beyond desired area.
• High velocity jetting can result in satellite
  flux droplets.

• Roller technology

• Contact application
• Easily cracks cells
• Excessive flux is applied
• Roller is not accurate to apply a consistent
  quantity of flux.

Flux flows beyond desired area of coverage.
Contact method causes cracking/breaking

• Conventional Air Atomization

• High velocity spray results in high degree of
  satellite flux droplets.

ULTRASONIC NOZZLE
AIR ATOMIZATION NOZZLE

• Ultrasonic nozzle

• Both jetting and air atomization highly
  susceptible to clogging
• Excessive overspray can cause additional
  problems

• Provides uniform, thin film coverage with
  small, atomized droplets

FLUXING AREA FOR A TYPICAL 1.5 3 MM SOLDER
BUS
SOLAR CELL
Not capable of providing thin flux coatings.
Thin flux layer deposits only on desired area.
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SelectaFlux for Fluxing Solder Bus Lines

• System Components Include

Power
Focus adjust air shroud
High speed solenoid valve
Bracket assembly with mounting holes
Ultrasonic Nozzle with button microbore
Flux reservoir w/level sensor and pressure relief
valve
Control module houses Ultrasonic Generator,
Electronics, timer, power supply, Idle/trigger
power PCA
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Product Line for Solar Cell Manufacturing

• Thin Film Solar Cells
• Deposition of active layers
• Deposition of buffer and/or organic layers
• Deposition of TCO
• Silicon Solar Cells
• SelectaFlux - Fluxing of Solder Bus on
  Tabber/Stringer machines
• ChemCoat Phosphoric/Boric Doping
• Solar Cell Packing
• 7. Anti-reflection Coatings

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ChemCoat for Phosphoric / Boric Doping

• Phosphoric or Boric acid doping is required to
  create the negative side of the P-N junction. The
  positive side is doped with boron. The P-N
  junction is responsible for creating a potential,
  through which freed electrons flow.

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N Type P Type Doping Methods

• Two Primary Methods Are Currently Used for N type
  Phosphoric Doping
• POCl3 Method Bubbling nitrogen through a
  phosphoric solution inside of a chamber to
  create a vapor that covers everything, including
  the wafers.
• Widely used and proven method
• 95 of wafers are doped using this method
• Slow batch process with a long cycle time
• Complex and expensive machinery
• Coats both sides of the wafer
• Inline Furnace Diffusion Uniformly spray
  coating solar cells with a phosphoric solution,
  then diffusing it into the cells using a high
  temperature oven.
• Inline, continuous manufacturing process
• Currently only 5 of the market
• Several new companies offering complete products
  (BTU, Schmidt, Despatch) that include a spray
  coater and oven combination
• Industry trend is moving in this direction due
  to lower manufacturing costs

P Type Boric Acid doping is done with tube
furnace BBr3 diffusion processes. ChemCoat
offers a cost effective alternative to any of
these doping methods.
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ChemCoat for Phosphoric / Boric Doping

• 38 (965 mm) spray coverage with 5 independent
  wafer sensors
• WideTrack stationary spray heads are proven for
  continuous wide area manufacturing lines
• Enclosed internal spray area with clear PVC
  viewing windows, polypropylene skins
• Fully integradable with high volume production
  lines
• Touch screen HMI interface for system monitoring
  and recipe management
• Drying gas for post-spray curing
• Non-clogging uniform spray
• Chemically resistant nozzle technology
• Chemically inert, long life polypropylene
  conveyor
• Zero maintenance, self-aligning, positive drive
  sprocket
• Automatic integrated belt cleaning system
• Intelligent spray controls allows selective
  coating width area for 1, 3 or 5 wafers across
  spray width
• Pressurized electronics
• Multi-level exhaust with monitoring

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Product Line for Solar Cell Manufacturing

• Thin Film Solar Cells
• Deposition of active layers
• Deposition of buffer and/or organic layers
• Deposition of TCO
• Silicon Solar Cells
• SelectaFlux - Fluxing of Solder Bus on
  Tabber/Stringer machines
• ChemCoat Phosphoric/Boric Doping
• Solar Cell Packing
• 7. Anti-reflection Coatings

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Anti-Reflection Coatings for Silicon and Thin
Film (Primarily Silicon Today)

• Helps reduce the reflection of desirable
  wavelengths from front glass of substrate and
  allows more light to reach the semiconductor film
  layer to operate more efficiently, more commonly
  used in Silicon applications.
• Anti-reflection layers are commonly made of
• TiO2
• SiO2
• Increases cell efficiency by roughly 3 4

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Sono-Tek Ultrasonic Coating Systems

• Installed in high-volume operations for solar
  cell manufacturers today

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Sono-Teks corporate headquarters are located in
Milton, NY USA, with additional offices in Hong
Kong. Our extensive global support and
distribution network provides factory trained
personnel with local language support in dozens
of countries worldwide.

• Fin.

SOLAR08R9PPT