Digital Material Deposition for Product Manufacturing Processes

Digital Material Deposition for Product

Manufacturing Processes

Material Deposition Presentation 2

Purpose of Presentation

Provide an overview of how the digital printing technologies utilized in the reprographics industry for over 50 years have been used for:

Unusual printing applications

Special material deposition applications


What is Digital Material Deposition?

The preparation of materials to make them suitable for digital deposition

The means (process, hardware, and controls) to enable the controlled lay-down of materials onto various substrates: Practiced in the reprographics industry for over 50 years

as copying & printing Processes and technologies have now been applied to a

wide variety of non-printing applications


Applications of Digital Deposition

The technologies of digital printing are being used to:

Make products Print on products Coat products Print on product containers Print on packaging Print labels


Advantages of Digital Deposition

Precise & controlled amounts of material lay-down Mass Thickness

Selectively variable process Change amounts and placement at will Create images - monochrome to full color Layered construction

High value material capability Little to no material wastage

Readily scalable From laboratory, to pilot, to production Short-run to long-run Narrow to wide format

3-Dimensional applications


Potential Disadvantages of Digital Deposition

Technology

Some systems can be complex Sometimes material latitudes are limited May be more costly on a cost per unit basis

than long-run conventional processes Offset Blade coating Pad printing


The Primary Forms of Deposition Materials

Deposition Materials can be : Liquid materials

or Dry powder materials

or Dry film materials


Widely Practiced Reprographic Deposition

(Printing) Systems Electrostatic (Dry powder and liquid)

Electrophotography Electrography

Inkjet (Liquid)

Drop on Demand Thermal & Piezoelectric

Continuous Thermal (Dry film)

Direct & Transfer Magnetographic (Dry powder)


Digital Deposition Processes Overview

Digital Deposition Processes

Latent ImageIntermediate

Direct-to-Receiver

Special ProcessReceiver Media

Electrophotography

Ionography

Electrography

Magnetography

Drop on Demand IJ

Continuous IJ

Thermal Transfer

Toner Jet

Dry Silver

Thermal Paper

Electrostatographic

UV Light Sensitive


Major Segmentation of Deposition

Technologies

Deposition system Direct versus Indirect

Material properties Liquid versus Dry


Major Segmentation Map

Direct Process Indirect Process

Liquid

Inkjet Electrostatic

ElectrophotographyElectrography

ElectrostaticElectrophotographyElectrography

Dry


Thermal Transfer


Magnetographic Solid Inkjet


Liquid vs. Dry

Conventional thinking for dispensing, dosing, metering: Liquid deposition via inkjet technology

The ‘de facto approach’

However, liquid AND dry powder materials can be digitally deposited Highly application dependent


Liquid Deposition & Micro-

dispensing


Continuous Drop-on-Demand

Piezoelectric

Edge shooterHollowTube

BinaryDeflection

MultipleDeflection

HertzMist

MagneticDeflection

Multi-Jet

Single Jet

Printhead Roadmap

Thermal Electrostatic Acoustic

Roof shooterBending Plate

Extending Member

Shear Mode


Inkjet Implementation: Fluid Issues

Fluid physical attributes and chemistry drive the system design:

• Aqueous or non-aqueous• Chemically reactive with print head• Viscosity versus temperature• Surface tension• pH• Volatility• Fluid temperature constraints• Fluid formulation modification latitude• Particulate size


Inkjet Implementation: Head Issues

All inkjet head types are possible candidates Head matched to the fluid and application:

Ejected volume and nozzle count requirements Jetting frequency requirement Throw distance and direction Number of unique fluid types required Head maintenance algorithms and hardware Ambient environment Reliability and operator interaction constraints


Inkjet Implementation: Substrate Issues

Like the fluid, the substrate is typically a given and influences the integration: x and y motion requirements

Speed, step size, and precision

Mounting and alignment Topography considerations Substrate - Fluid interactions


Inkjet Implementation: Other Challenges

Head-drive electronics and algorithms Data source and manipulation requirements Environmental concerns

Temperature and humidity Outside contaminants Process effluents

Drying

Example:Polymer Electronics -

Displays

Ejection of electro-luminescent polymer onto glass substrate for monochrome or color displays

ADVANTAGE• Inexpensive• Automated• Repeatable• “Displays-on-

Demand”

Example:Polymer Electronics -

Sensors

Ejection of “environmentally sensitive” polymer onto silicon or advanced PCB substrate

ADVANTAGE• Inexpensiv

e• Automated• Repeatabl

e• “Sensors-

on- Demand”


Layer-upon-layer fluid ejection to build computer-generated, three-dimensional parts and prototypes.

Example: Rapid Prototyping – SLA

Substitute

ADVANTAGE• Inexpensive• Automated• Repeatable• “Parts-on-

Demand”


Manufacturing Dispensing Examples

Flexible adhesive placement, coating, soldering, and precise patterning for in-line and off-line production

ADVANTAGE• Automated• Repeatable• Quantity-controlled

dispensing


Example: Manufacturing – Dispensing

Solder

25µm bumps of 63/37 solder deposited on 35µm pitch using “Solder Jet” technology

Example: Pharmaceutical – Dispense Active

Agent Advanced drug-dispensing system Active agent(s) stored in carrier wells that are

filled on demand by specialized inkjet heads

ADVANTAGE

Increased medical control over drug application

Drugs tailored to individual’s medical requirements

Example: Biotechnology – DNA Testing

HP partnership with Affymetrix Gene Chip Dispensing of “tiny DNA segments, housed

inside picoliter-size droplets of liquid … onto an array of integrated circuit-like chips…”

Source: Upside, Sept. 23, 1998 (www.upside.com)

ADVANTAGE Automated procedures Repeatable results

Example: Medical - Containment

Hydrophobic material forms barrier to contain biological fluids or other fluids for tissue preparation

ADVANTAGE• Automated• Pattern retention• Repeatable

processes


A Case Study – Liquid Deposition

Precision coating of a medical device for drug loading

Project performed by Xactiv Inc, www.xactiv.com (formerly Torrey Pines Research)

The development activity was carried out on behalf of a client

http://www.xactiv.com/


Case Study – Stent Coating

Stent – small, lattice-shaped, metal tube that is inserted permanently into an artery. The stent helps hold open an artery so that blood can flow through it.


Case Study – Stent Coating Requirements

Drug eluting stent is coated with polymer that incorporates a drug that helps prevent plaque build-up

Drug elutes very slowly over a period of years Coating must be applied uniformly on inside and

outside of stent Coating thickness must be very uniform (+/- 5%) Coating weight stent to stent must be well

controlled (+/- 5%) Stents of various diameters and lengths


Case Study – Stent Coating Challenges

Coating materials pre-defined by client Polymer has few viable solvents

Stent must be coated all over while handling Precision requirement Minimize wastage Speed


Case Study – Stent Coating Solution

Piezo industrial drop on demand system selected

Dimatix S-series print head Resistant to solvents Precision jetting system

TPR modified the print head Replaced seals


Case Study – Stent Coating Solution

Piezo drop on demand industrial print head Modified seals to withstand solvent

Custom designed stent handling system Custom designed precision inkjet coating system Special maintenance algorithms and maintenance

system Eliminate nozzle blockage due to drying

Solvent resistant fluid handling Solvent chemistry Ink development



Precision stent handling system



Precision inkjet coating system


Case Study – Stent Coating System


Dry Powder Deposition


Electrostatic Dry Powder Deposition Typical Application

Requirements

Dry powder materials From ~ 5 to 75 microns in size

Solvent-less process High area coverage - usually

Large volumes of material Precise metering/thickness control Uniform coating Static or variable information Contact or non-contact process Direct or indirect process 2D or 3D deposition


Conventional Powder Coating

Charging air gun

Typical powder spray system


Conventional Powder Coating

Problems/Limitations Corona or tribo charging with air transport

Poor powder charging Poor directional control Air overwhelms electric field and wastes material

• Requires substantial post “clean-up”

Uniformity not assured Masking difficult Images with information impossible


The Challenges of Electrostatic Powder Development

Using/modifying or creating the materials for: Functional requirements of application Charging Transport

Identifying a suitable powder Development Sub-system technology Direct versus Indirect architecture

Dealing with Substrate properties Often a given


Important Powder Properties Dielectric properties

Insulative versus conductive Magnetic properties Powder size and size distribution Electrostatic charging characteristics Rheological (melt) properties Flow properties Functional characteristics

Color Application dependent functionality


Important Substrate Properties

Dielectric properties Insulative versus conductive

Flat or 3D If flat

Sheet vs. roll stock Flatness tolerance

If 3D Shape and 3D depth

Layered construction characteristics Hard vs. soft characteristics


Dry Powder Deposition System Considerations

Conductive Insulative Magnetic Non-magnetic

Powder Properties

Conductive Insulative

Substrate Properties

Triboelectrification Induction

Charging Method

Direct Transfer

Deposition Method


What are Conductive Materials

It depends on time for current to flow: With copper – not very long With fused quartz - sit down because you’re

going to be there a while

Conductivity represents a continuum


Conductivity is a Continuum

In conductors, electric charges are free to move In an insulator, charges are less free to move There’s no such thing as a perfect insulator

However, insulating ability of fused quartz is 1025 times that of copper

Conductivity is characterized by a physical property - Resistivity

ConductiveMaterials

InsulativeMaterials

Semi-conductiveMaterials


Resistivity of a ‘Conductive’ Material

A conductive material for many electrostatic processes may have a resistivity of 7.5(108) ohm-cm or less.

0 – 10-8

Most Metals 108 10101018

Fused Quartz

ConductiveMaterials

InsulativeMaterials

??

Resistivity Scale (ohm-cm)


The Significant Properties that Drive the Electrostatic

Deposition Process

Powder charging Determined by the material being Conductive

versus Insulative

Powder transport Determined by the material being Magnetic

versus Non-magnetic


Charging of Insulative Powders

Insulative Material Charging Most commonly charged by

triboelectrification Mechanical contact/rubbing causes

charges to exchange

- ----+

+

++

++

++

+

+

++

++

++- ----

- ----- ----

- ----

- ----Functional Powder

Carrier


Triboelectric Series

Steel, WoodAmber, Sealing Wax

Hard Rubber, Nickel, CopperGrass, Silver, Gold Platinum

Sulfur, Acetate, RayonPolyester, Celluloid

Orlon, SaranPolyurethane, PolyethylenePolypropylene, PVC (Vinyl)

Kel-F (CTFE)SiliconTeflon

I ncr

easi

ngl

y P

osit

ive

Incr

easi

ngl

y N

egat

ive

COTTON – The Dividing Point

AirHuman Hands

AsbestosRabbit Fur

GlassMica

Human HairNylonWoolFur

LeadSilk

AluminumPaper


Powder Charge Distribution

5 10 15 20 25 30

Charge - C/gm

VO

LU

ME

(N

um

ber)

-5

WrongSign

LowCharge

Target HighCharge


Charging of Conductive Powders

Conductive Materials Most commonly charged by Induction

An applied voltage causes electrons to migrate to the tip of the material in the presence of an electric field (E)

V

_

---- +


Powder Transport

Magnetically permeable powders are most commonly transported via magnetic forces

Powder can be magnetically permeable

or Can incorporate a magnetic Carrier

N

S

N S

NS

N

SDevelopmentZone

Su

bs

tra

te


What about the Substrate?

The substrate is the material upon which the powder is being deposited. It ultimately refers to the final working material for the given

application. Examples might include:

Electronic materials Flexible circuits PCB materials

Pharmaceutical tablet Consumer products Product packaging Food products

The substrate can be conductive or insulative Its properties will dictate the powder and transfer method


Electrostatic Deposition Material Choices

PowdersInsul Cond

Insul Yes YesSubstrate

Cond Yes Yes

The physics to follow


Dry Powder Development

• Purpose• Apply powder particles to the electrostatic latent image on the photoreceptor or electrostatically charged receiver

• Functions• Charge the powder• Transport powder into the “development zone”• Fully develop the image, not the background


Summary

The challenges of Electrostatic Deposition of Dry Powder include: Material formulation (Powder and Substrate) Charge methodology Transport means Transfer mechanism

Many deposition technologies exist from the fields of Electrophotography and Electrography

The advantages of electrostatic dry powder deposition include: Dry powder applications Speed Scalable to wide format No solvents


A Case Study – Powder Deposition

Dry powder coating of pharmaceutical tablets for coating and/or drug loading

Project performed by Xactiv, Inc, www.xactiv.com (formerly Torrey Pines Research)

The development activity was carried out on behalf of Phoqus Limited, www.phoqus.com



Tablet Coating

Most tablets are coated to: Protect the tablet Seal the tablet

From environment Taste masking

Control drug release Create brand

identification Create desirable

appearance


Tablet Coating Process Today

Batch process

Solvent based

Tumble dried


Problems with the Current Process

Liquids and solvents Compatibility problems with certain drug actives Environmental problems Drying costs

Quality Tablet damage due to aggressive tumbling Variation in coating thickness

Batch process Minimum lot size very large No individual tablet customization Expensive wastage if problems occur

Not suitable for certain tablets, such as fast dissolving dosage forms


The Technical Challenges

The challenges over those normally encountered in Reprographics Industry: 3-D Tablet Surface

Most printing done on flat surfaces Use of many different powders and tablets

In printing, there is typically one set of materials for a given machine

Precision +/- 10% typical in printing +/- 2% required for this application


The Solution

Improve, Customize, and Optimize “Electrostatic Dry-Powder Development” (EDPD) As practiced in the Reprographics Industry for over 50 years


Deposition Applicator of Choice

Rotating magnet DCD system Permanently magnetized carrier

Both provide vigorous mixing in development zone


Pharmaceutical EDPD Housing

Elements Licensed from Heidelberg


Critical Coating Materials

DCD Carrier materials Strontium and manganese ferrite powder, 40 – 80 Silicone, Acrylic or Fluoro-Silicone coated

Coating powders Many formulations Various proprietary resins Water soluble Low glass transition temperatures


Tablet Holding Requirements

Securely hold individual tablets Make electrical contact to body of tablet Create an electrical shield:

To prevent contamination of holder Shut-down development of powder on tablet


Tablet Holder

Ejector/Electrode

ConductiveFlexible Cup

Shield(reverse biased)

Vacuum Connection


Coating Uniformity Issues

Electric Field is a function of voltage difference and dielectric distance In conventional coating practice, coating thickness varies with field In copiers/printers, field is uniform because coated surface is flat. Tablet

is not flat, so field varies and coating thickness will vary

Strong field

Weak field

Weak field


Field Collapse Process

1 2

3 4

Time = 0

Time = Completion

E = maximum

E = 0E

E


Coating Uniformity Results

Section through the corner of an EDPD coated tablet showing uniformity of coating on top and around the edge


Continuous Process

Section of coating drum with tablets


The Finished Product


A Case Study – Powder Deposition

Dry powder coating to make fuel cell electrodes Activity performed by Xactiv, www.xactiv.com

(formerly Torrey Pines Research) Independent activity resulting in significant IP US Patent now issued Prepares Xactiv for position in renewable energy

markets



Electrostatic Deposition(Intermediate Dielectric Substrate)

60% PtC and 40% PTFE mixture is conducting

Apply voltage between conducting mixture and dielectric coated electrode

Monolayer of PtC/PTFE particles is induction charged and electrostatically attracted to dielectric

VA


Electrostatic Deposition Problems(Intermediate Dielectric Substrate)

Some non-uniformity of deposited layer requires conditioning

Monolayer is only ~0.5 mg/cm2

Multiple transfix steps would be required to achieve target Pt loadings

Need to repeatedly clean and neutralize intermediate dielectric substrate


Xactiv Conductive-Conductive DepositionParticle Induction Charging & Detachment via Field Intensification

VA

Electric FieldIntensification for

Induction Charging& Detachment

Weak Electric Fieldfor Deposition

Electrodestructures


Xactiv Cond-Cond ImplementationMagnetic Brush Deposition

Carbon Paper

NS

NS

N SNS

NS

NSN

S

NS

Paddle WheelElevator & Metering

Cross Mixer

Magnetic BrushRotating MagnetsStationary Sleeve

Air Gap


Magnetic Brush Unit


Magnetic Brush Structure


Magnetic Brush Forces

Carbon Paper

N

VA


Non Contact Magnetic Brush Deposition

Carbon Paper

N

VA

Electric field intensified forinduction charging & detachment of PtC/PTFE blend


Surrogate “Tribo” FixtureTheory

N S N SS

Motor

VA

Enables rapid evaluation of materials, concentrations,blend and mixing conditions.


“Tribo” Fixture


PtC/PTFE on Carbon Paper


Deposited Powder Characteristics

PtC/PTFE powder layer has electrostatic adhesion/cohesion but is low

The magnetic brush must be gapped from the carbon paper to enable multilayer powder deposition

Q/M of powder blend depends on applied voltage but magnitude independent of polarity

Since magnetic brush architectures prefer underside deposition on a receiver, a minimum vacuum can be provided for increasing the powder adhesion during the electrostatic deposition process


0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 1 2 3 4 5 6 7 8

Number of Depositions

Mas

s/un

it a

rea

(mg/

cm2 ) 5% Developer .25 gram loading

11% Developer .15 gram loading

PtC/PTFE Density vs Depositionswith “Tribo” Fixture(Fixed field, Blend of 60% 15%PtC & 40% Teflon mixed with carrier)

Require ~5 & ~10 mg/cm2 for anode and cathode, respectively


Carbon/Teflon powder blend (60%/40%) at 5% with carrier

-20

-10

0

10

20

-3000 -2000 -1000 0 1000 2000 3000

Applied Voltage (volts)

Q/M

(

C/g

) &

D

etac

hm

ent

(%)

Q/M

Detachment

Q/M & Percent Powder Detachment


Vacuum AssistedMagnetic Brush Deposition

NS

NS

N S

NS

NS

NSN

S

NS

Carbon Paper

Porous/ConductingSupport

Vacuum Plenum

VA


What This Means

Ability to electrostatically deposit conductive &/or insulative powder blends

Ability to deposit thin or thick layers of powder blend onto conductive substrate

Control of layer thickness by electrostatic field strength (voltage and distance) and dwell time (process speed)

Enables low cost continuous manufacturing process Dry deposition method can enable improved fuel cell

performance by circumventing possible platinum catalyst contamination by current wet methods

04/21/23 Torrey Pines Research, Inc. 90

Transport Belt withElectrostatic Grip

Developer unitCarbon

Paper Feed

PowderConsolidationRadiant Heat

Sintering

Electrode Fabrication Process

• Sheet fed architecture shown, may also be configured as a web fed system• Multiple Developer units can be used for multiple layers or multiple depositions


Linear Plate Translator & Magnetic Brush


Powder Blend Deposition on Carbon Paper

10 cm square carbon paper attached to holder with porous plate for vacuum assist

Developer with 60% PtC (10% Pt) and 40% Teflon blend mixed with permanently magnetized ferrite carrier beads at concentration of 4%

500 g of mixture loaded in developer unit sump of 12 cm width Magnet assembly rotated at 50 rpm, and carbon paper

translated at speed of 2mm/s Carbon paper biased at +2000 volts across 5mm gap Deposit 4.2 mg/cm2 of powder blend after 2 passes Production system would use 2 rolls in a single pass


Powder Blend Consolidation

Particle-to-particle contact of Teflon required prior to heating Achieved by compacting the powder layer with pressure 10 cm square samples consolidated with pressure (200 psi)

from hydraulic press Rubber sheet (3 mm thick) attached to one of the two pressure

plates Release layer (paper) in contact with powder Roll pressure likely feasible for production environment


Powder Blend Sintering

Nitrogen purged oven at 355oC used to sinter consolidated powder on carbon paper for 4 min.

Alternative sintering methods are likely feasible for production environment Resistive heating of carbon paper in inert atmosphere Flash radiant heating


Sintering via Flash Radiant Heating

Carbon Paper

Transport Belt

PtC/PTFE

N2 ?Flash Lamp Cavity


Results – Surface Morphology

25x 500x


Results - Dispersion Uniformity

SEM from Deposited LayerPlatinum Carbon Fluorine


Results - Functionality

Deposited ~ 5 mg/cm2 on 4”x4” carbon paper Consolidated and sintered layer Measured 75% of ‘normal’ platinum Assembled as electrode into fuel cell test module Exceeded ‘normal’ cell output at 200mA/cm2

No degradation after 6 months of operation


Any Questions???

Digital Material Deposition for Product Manufacturing Processes

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