Date post: | 16-Dec-2015 |
Category: |
Documents |
Upload: | billy-westrup |
View: | 229 times |
Download: | 0 times |
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
Material Deposition Presentation 3
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
Material Deposition Presentation 4
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
Material Deposition Presentation 5
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
Material Deposition Presentation 6
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
Material Deposition Presentation 7
The Primary Forms of Deposition Materials
Deposition Materials can be : Liquid materials
or Dry powder materials
or Dry film materials
Material Deposition Presentation 8
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)
Material Deposition Presentation 9
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
Material Deposition Presentation 10
Major Segmentation of Deposition
Technologies
Deposition system Direct versus Indirect
Material properties Liquid versus Dry
Material Deposition Presentation 11
Major Segmentation Map
Direct Process Indirect Process
Liquid
Inkjet Electrostatic
ElectrophotographyElectrography
ElectrostaticElectrophotographyElectrography
Dry
ElectrostaticElectrophotographyElectrography
Thermal Transfer
ElectrostaticElectrophotographyElectrography
Magnetographic Solid Inkjet
Material Deposition Presentation 12
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
Material Deposition Presentation 13
Liquid Deposition & Micro-
dispensing
Material Deposition Presentation 14
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
Material Deposition Presentation 15
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
Material Deposition Presentation 16
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
Material Deposition Presentation 17
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
Material Deposition Presentation 18
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”
Material Deposition Presentation 21
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”
Material Deposition Presentation 22
Manufacturing Dispensing Examples
Flexible adhesive placement, coating, soldering, and precise patterning for in-line and off-line production
ADVANTAGE• Automated• Repeatable• Quantity-controlled
dispensing
Material Deposition Presentation 23
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
Material Deposition Presentation 27
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
Material Deposition Presentation 28
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.
Material Deposition Presentation 29
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
Material Deposition Presentation 30
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
Material Deposition Presentation 31
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
Material Deposition Presentation 32
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
Material Deposition Presentation 33
Case Study – Stent Coating
Precision stent handling system
Material Deposition Presentation 34
Case Study – Stent Coating
Precision inkjet coating system
Material Deposition Presentation 35
Case Study – Stent Coating System
Material Deposition Presentation 36
Dry Powder Deposition
Material Deposition Presentation 37
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
Material Deposition Presentation 38
Conventional Powder Coating
Charging air gun
Typical powder spray system
Material Deposition Presentation 39
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
Material Deposition Presentation 40
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
Material Deposition Presentation 41
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
Material Deposition Presentation 42
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
Material Deposition Presentation 43
Dry Powder Deposition System Considerations
Conductive Insulative Magnetic Non-magnetic
Powder Properties
Conductive Insulative
Substrate Properties
Triboelectrification Induction
Charging Method
Direct Transfer
Deposition Method
Material Deposition Presentation 44
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
Material Deposition Presentation 45
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
Material Deposition Presentation 46
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)
Material Deposition Presentation 47
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
Material Deposition Presentation 48
Charging of Insulative Powders
Insulative Material Charging Most commonly charged by
triboelectrification Mechanical contact/rubbing causes
charges to exchange
- ----+
+
++
++
++
+
+
++
++
++- ----
- ----- ----
- ----
- ----Functional Powder
Carrier
Material Deposition Presentation 49
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
Material Deposition Presentation 50
Powder Charge Distribution
5 10 15 20 25 30
Charge - C/gm
VO
LU
ME
(N
um
ber)
-5
WrongSign
LowCharge
Target HighCharge
Material Deposition Presentation 51
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
_
---- +
Material Deposition Presentation 52
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
Material Deposition Presentation 53
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
Material Deposition Presentation 54
Electrostatic Deposition Material Choices
PowdersInsul Cond
Insul Yes YesSubstrate
Cond Yes Yes
The physics to follow
Material Deposition Presentation 55
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
Material Deposition Presentation 56
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
Material Deposition Presentation 57
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
Material Deposition Presentation 58
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
Material Deposition Presentation 59
Tablet Coating Process Today
Batch process
Solvent based
Tumble dried
Material Deposition Presentation 60
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
Material Deposition Presentation 61
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
Material Deposition Presentation 62
The Solution
Improve, Customize, and Optimize “Electrostatic Dry-Powder Development” (EDPD) As practiced in the Reprographics Industry for over 50 years
Material Deposition Presentation 63
Deposition Applicator of Choice
Rotating magnet DCD system Permanently magnetized carrier
Both provide vigorous mixing in development zone
Material Deposition Presentation 64
Pharmaceutical EDPD Housing
Elements Licensed from Heidelberg
Material Deposition Presentation 65
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
Material Deposition Presentation 66
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
Material Deposition Presentation 67
Tablet Holder
Ejector/Electrode
ConductiveFlexible Cup
Shield(reverse biased)
Vacuum Connection
Material Deposition Presentation 68
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
Material Deposition Presentation 69
Field Collapse Process
1 2
3 4
Time = 0
Time = Completion
E = maximum
E = 0E
E
Material Deposition Presentation 70
Coating Uniformity Results
Section through the corner of an EDPD coated tablet showing uniformity of coating on top and around the edge
Material Deposition Presentation 71
Continuous Process
Section of coating drum with tablets
Material Deposition Presentation 72
The Finished Product
Material Deposition Presentation 73
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
Material Deposition Presentation 74
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
Material Deposition Presentation 75
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
Material Deposition Presentation 76
Xactiv Conductive-Conductive DepositionParticle Induction Charging & Detachment via Field Intensification
VA
Electric FieldIntensification for
Induction Charging& Detachment
Weak Electric Fieldfor Deposition
Electrodestructures
Material Deposition Presentation 77
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
Material Deposition Presentation 78
Magnetic Brush Unit
Material Deposition Presentation 79
Magnetic Brush Structure
Material Deposition Presentation 80
Magnetic Brush Forces
Carbon Paper
N
VA
Material Deposition Presentation 81
Non Contact Magnetic Brush Deposition
Carbon Paper
N
VA
Electric field intensified forinduction charging & detachment of PtC/PTFE blend
Material Deposition Presentation 82
Surrogate “Tribo” FixtureTheory
N S N SS
Motor
VA
Enables rapid evaluation of materials, concentrations,blend and mixing conditions.
Material Deposition Presentation 83
“Tribo” Fixture
Material Deposition Presentation 84
PtC/PTFE on Carbon Paper
Material Deposition Presentation 85
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
Material Deposition Presentation 86
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
Material Deposition Presentation 87
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
Material Deposition Presentation 88
Vacuum AssistedMagnetic Brush Deposition
NS
NS
N S
NS
NS
NSN
S
NS
Carbon Paper
Porous/ConductingSupport
Vacuum Plenum
VA
Material Deposition Presentation 89
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
04/18/23 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
Material Deposition Presentation 91
Linear Plate Translator & Magnetic Brush
Material Deposition Presentation 92
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
Material Deposition Presentation 93
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
Material Deposition Presentation 94
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
Material Deposition Presentation 95
Sintering via Flash Radiant Heating
Carbon Paper
Transport Belt
PtC/PTFE
N2 ?Flash Lamp Cavity
Material Deposition Presentation 96
Results – Surface Morphology
25x 500x
Material Deposition Presentation 97
Results - Dispersion Uniformity
SEM from Deposited LayerPlatinum Carbon Fluorine
Material Deposition Presentation 98
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
Material Deposition Presentation 99
Any Questions???