Particles! Workshop materials Screen printing technology Aerosol processing of materials 7/28/09...

Particles!

Workshop materials

Screen printing technology

Aerosol processing of materials

7/28/09

Sheryl Ehrman

Particles! workshop plan

• 3:30-3:45 Intro to workshop, introductions to each other• 3:45-4:30 Introduction to particle technology

– Particle technology basics– Air pollution

• 4:30-5:15 Laboratory tours - flame reactor, metal powder reactor• 5:15-5:45 Where are the particles, conductive pastes activity• 5:45-6:45 dinner• 6:45-7:45 How are the circuit boards printed? Screen printing

activity. Important powder properties, flowability activity• 7:45-8:45 Details about our process to make the powders,

design activities• 8:45-9 Wrap up and clean up

http://www.eickmeyer.com/Gebrauchtliste/05-1/Siebdruckmaschine-Thieme520.jpg

http://www.zanafilla.net/screen_printer_mid.jpg

http://images.pennnet.com/articles/smt/thm/th_0612smt_screen02.jpg

http://www.gsiglasers.com/UserFiles/Images/Market%20Sectors/Electronics/precision_cutting.jpg

Size,compositioncontrol

Avoid agglomeration

Quantity/cost

Holy grail

Our laboratory’s approach: • develop processes for niche applications • only one or two of the objectives required• make use of aerosol approaches when advantageous

Particle processing – general goals

Particles, how to make them

• Top down– Milling– Refining micron scale patterning techniques

• Bottom up– From atoms or molecules to clusters to particles

to macroscale materials

Methods of making fine particles

• Starting from molecular level– From precursor

Aerosol• Combustion synthesis

• Thermal or plasma synthesis

Solution phase synthesis• Precipitation

• Sol gel

• Emulsion

– Evaporation/condensation

• Starting from cluster level– Spray pyrolysis– Electrospray

Aerosol example: Cu doped ceria

Water cooled substrate for particle deposition

CH4

O2

N2 Burner

Nebulizer

Compressed Air

Rotameters

Metal acetate precursors0.3 mol /l in water

R.K. Pati, S. Hou, O. Akhuemonkhan, I.C. Lee, D. Chu, S.H. Ehrman, submitted (2006)

Solution phase example: Fe nanoparticles

9.508.75

K.C. Huang and S.H. Ehrman, Langmuir, in press (2006)

•Precipitation of iron from iron chloride in presence of sodium borohydride and trace amount of palladium ions as seeds•Polyacrylic acid added as dispersing agent

Why the emphasis on aerosol processes in our lab?

• Advantages in some cases: – Rapid– Simple, less steps required– No solvents – Amenable to continuous processing– Potential for scalablity

Disadvantages

• Poor size control• Poor control of aggregation• Difficult to make non-oxides

– Interesting alternatives - sodium coated metal nanoparticles (Axelbaum, Zachariah) in aerosol process

• May battle thermodynamics in mixed systems

Aerosol manufacturing, $$

Product Volume, tons/yr

Market

$/yr

Process

Carbon black 8 M 8 B Flame

Titania 2 M 4 B Flame

Fumed silica 0.2 M 2 B Flame

Zinc oxide 0.6 M 0.7 B Hot wall furnace

Fe, Pt, CeO2 0.02 M 0.3 B Hot wall furnace, spray pyrolysis

Ref: K. Wegner, S.E. Pratsinis, Chem. Eng. Sci. 51, 4581 (2003)

Metal powders for conductive pastes

DuPont uses 400,000 kg of precious metal per year to make their pastes

Prices:Silver - 13.90/ounceGold - 950/ouncePalladium - 260/ounceCopper - 2.50/pound Nickel - 7.54/pound

General Aerosol Process Schematic

Feed #1Preparation

Feed #2Preparation

.

.

.

Feed #NPreparation

• Vaporization• Pumping/Compression• Addition of additives• Preheating

© R.B. Diemer, Jr. 2005

Schematic developed by R. Bertrum Diemer, DuPont

AerosolReactor

Feed #1Preparation

Feed #2Preparation

.

.

.

Feed #NPreparation

• Mixing• Reaction Residence Time• Particle Formation/Growth Control• Agglomeration Control• Cooling/Heating• Wall Scale Removal



AerosolReactor

Base PowderRecovery

• Gas-Solid Separation

Feed #1Preparation

Feed #2Preparation

.

.

.

Feed #NPreparation



AerosolReactor

Base PowderRecovery

OffgasTreatment

Feed #1Preparation

Feed #2Preparation

.

.

.

Feed #NPreparation

TreatmentReagents Waste

• Absorption

• Adsorption

Vent or Recycle Gas



AerosolReactor

Base PowderRecovery

OffgasTreatment

PowderRefining

Feed #1Preparation

Feed #2Preparation

.

.

.

Feed #NPreparation


Coarseand/or FineRecycle

Vent or Recycle Gas

• Size Modification

• Solid Separations

• Degassing• Desorption• Conveying



AerosolReactor

Base PowderRecovery

OffgasTreatment

ProductFormulation

PowderRefining

Feed #1Preparation

Feed #2Preparation

.

.

.

Feed #NPreparation

FormulatingReagents



Vent or Recycle Gas

• Coating• Additives• Tabletting• Briquetting• Granulation• Slurrying• Filtration• Drying



AerosolReactor

Base PowderRecovery

OffgasTreatment

ProductFormulation

Packaging

PowderRefining

Feed #1Preparation

Feed #2Preparation

.

.

.

Feed #NPreparation

FormulatingReagents


Product


Vent or Recycle Gas

• Bags• Super Sacks• Jugs• Bulk

containers– trucks– tank cars



AerosolReactor

Base PowderRecovery

OffgasTreatment

ProductFormulation

Packaging

PowderRefining

Feed #1Preparation

Feed #2Preparation

.

.

.

Feed #NPreparation

FormulatingReagents


Product


Vent or Recycle Gas



Particle Synthesis Setup

Compressed Nitrogen

Atomizer(RETEC)

Diffusion Dryer

(TSI Model 3062)

Reactor Furnace

(Lindberg)

Temperature: 300 °C ~ 1000 °C

Powder Collection

(X-ray Diffraction)

By-Pass

(R.T. control)

Precursors

0.3 M precursor in water/alcohol solution (10% by volume)

Colors of Copper Powders300 °C

450 °C

600 °C

1000 °C

Cu·N

Cu·N +ETOH

Cu·Ac

Cu·Ac + ETOH

Pure Cu

Image J.-H. Kim

Other results with alcohol

• Can make phase pure copper from copper nitrate

• Enable formation of copper acetate at lower temperatures

• Works for nickel nitrate too!• ~ 0.1 mol % H2 estimated,

well below flammability limit in air

Particle synthesis(polydisperse)

Temperature also important

Scanning Electron Microscope Images, JH Kim

Polydisperse Copper Powders

CuCu: 600 °C CuCu: 1000 °C

From copper nitrate with co-solvent

Spray pyrolysis processes

(adapted from Gurav et al., Aerosol Sci. and Tech., 1993)

http://resources.metapress.com/pdf-preview.axd?code=t1r6110741380195&size=largest

Composition is a variable

What composition will give you a melting point of 1100 K and the highest conductivity possible?

What composition will give you a melting point of 1250 K and the highest conductivity possible?

Particle diameter is a variableWe want 1 micron diameter particles

Equations

dd Droplet diameter

dp Particle diameter

CMp Mass concentration

p Density of copper nitrate solid

dd dp

droplet dry salt end particle

Now we want to make lots of particles

Process scale up calculation

Wrap up

• Particle technology, it’s everywhere!• One application, metal powders for

conductive pastes, everywhere too, big business!

• Particle properties are important for patterning the conductive pastes

• Lots of chemical engineering goes into developing the process to make the metal powders!

So what’s a micro or nanoparticle?

• Micro: particle < 100 microns in diameter• Nano: particle < 100 nanometers in diameter• May form larger structures: agglomerates, films

• These can be 100’s of microns in size

500

nmSize selected Cu npsTop view of film of TiO2 nps

100 nm

CuO/CeO2 npsCu microparticles

Particles are everywhere!

• Pollen? Soot? Viruses?

Calicivirus Polio VirusAll images Bar = 50 nm Photo Credit: F.P. Williams, U.S. EPA

More images for public use at http://www.epa.gov/nerlcwww/

Pollen http://www.e-microscopy.com/upload/img/misc_pollen.jpg

http://www.mpbs.wnoz.us.edu.pl/moje_sadze/soot_b.jpg

Beneficial particles

http://www.sptimes.com/2002/03/29/photos/ht-sunscreen.jpg

http://www.nanophase.com/catalog/item.asp?ITEM_ID=41&DEPARTMENT_ID=38

http://www.aafa.org/pictures/dpi.jpg

http://www.mpbs.wnoz.us.edu.pl/moje_sadze/soot_b.jpg

Particles (nano) in the past

• Lampblack (carbon black) produced in quantity by the ancient Chinese

• Pigments used by other civilizations several hundred years BC in glass and other ceramics

• Examples of nano in the not so-distant past…

Ref. G. Ulrich,Chemical and Engineering News, 1984

Ref: Johnson, P. H., and Eberline, C. R., “Carbon Black, Furnace Black”, Encyclopedia of Chemical Processing and Design, J. J. McKetta, ed., Vol. 6, Marcel Dekker, 1978, pp. 187-257.

Particles in the lab

• Studies of reactions of halogen compounds in hydrogen flames, late 1960’s, early 1970’s

• 1970’s application of this towards making optical fibers• Bell Laboratories research• “Modified Chemical Vapor Deposition”

Ref: Simpkins PG, Greenbergkosinki S., MacChesney JB, Journal of Applied Physics, 50 (9)

5676 (1979).

Particles in industry - Vapor-phase axial deposition of optical fiber preforms

start with rod (preform) of pure silica, SiO2

O2/H2 burnerproduces nanoparticlesof silica + Ge, Ti,B, P etc…

graphite furnaceto consolidatefume

consolidatedpreform is drawn into optical fiber

H2, O2, SiCl4 + GeCl4 + TiCl4...

Particles in the lab – Optical behaviorSize dependent optical properties

• CdSe nanoparticles, synthesized in solution

• monodisperse size, different sizes in each vial

• illuminated with UV light

• emitting different (size dependent) wavelengths of visible light

• phenomena result of size-dependent quantum confinement

image: Felice Frankel, MITparticles: Moungi Bawendi’s group at MIT, Department of ChemistryRef: Tobin JG, Colvin VL, Alivasatos AP, Phys. Rev. Let. 66 (21) 2786 (1991)Murray CB, Norris DH, Bawendi MG, J. Am. Chem. Soc., 115 (19) 8706 (1993)

Particles in the market place

• Commercially available nanoparticles, for example Qdots

• Can be functionalized to bind to specific targets

• Used extensively today for diagnostics in biotechnologyHere, dual labeled mouse fibroblasts. Actin stained red. Nuclear membrane labeled with red and green probes, appearing yellow.

Nano in the lab – electronic behavior Single electron transistors

• a single electron excess charge on a particle markedly changes its conductive

properties • could eventually lead to orders of

magnitude decrease in device size

• huge implications for computing

• Difficulties: – stability at T >> 0 K ?

– manufacturing in quantity?

– how to pattern/order them?

Doped Si substrate

SiO2 insulating layer

gold leads + linker molecules

nanoparticles

after Klein et al., Nature, 389, 699 (1997)

Nano in the marketplace• Still waiting on this one…• Meanwhile… top down getting really small, sub 0.2

micron feature size in an integrated circuit• Two new nano issues

– Polishing at nano level between processing steps– Small features -> contaminants = killer nano particles!!

http://www.semiconductor-technology.com/projects/rf/rf1.html

Nano in the marketplace• Killer particles? • Rule of thumb: particle > 1/3

of smallest feature size can cause killer defect

• Defect detection– Performance after production– On-line, light scattering

• At these size scales, on-line very challenging!

http://www.geek.com/news/geeknews/2006Jan/bch20060126034439.htm

In my lab, what do we do?

• As chemical engineers we develop processes for making inorganic nanoparticles and nanoparticle based materials

• It’s a great time for chemical engineers to get involved – Relevance of manufacturing to enabling this technology – Ability to characterize improving rapidly

Particles! Workshop materials Screen printing technology Aerosol processing of materials 7/28/09...

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