Digital Material Deposition for Product Manufacturing Processes

1
Digital Material Deposition for Product
Manufacturing Processes
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

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

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

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

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

7
The Primary Forms of Deposition Materials

• Deposition Materials can be
• Liquid materials
• or
• Dry powder materials
• or
• Dry film materials

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)

9
Digital Deposition Processes Overview
10
Major Segmentation of Deposition Technologies

• Deposition system
• Direct versus Indirect
• Material properties
• Liquid versus Dry

11
Major Segmentation Map
Direct Process Indirect Process
Liquid Inkjet Electrostatic Electrophotography Electrography Electrostatic Electrophotography Electrography
Dry Electrostatic Electrophotography Electrography Thermal Transfer Electrostatic Electrophotography Electrography Magnetographic Solid Inkjet
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

13
Liquid Deposition Micro-dispensing
14
Printhead Roadmap
Continuous
Drop-on-Demand
Piezoelectric
Electrostatic
Acoustic
Thermal
Multiple Deflection
Hollow Tube
Edge shooter
Single Jet
Multi-Jet
Roof shooter
Bending Plate
Binary Deflection
Extending Member
Hertz Mist
Shear Mode
Magnetic Deflection
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

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

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

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

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

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

20
ExamplePolymer Electronics - Sensors
Ejection of environmentally sensitive polymer
onto silicon or advanced PCB substrate

• ADVANTAGE
• Inexpensive
• Automated
• Repeatable
• Sensors-on- Demand

21
Example Rapid Prototyping SLA Substitute

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

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

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Manufacturing Dispensing Examples

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

• ADVANTAGE
• Automated
• Repeatable
• Quantity-controlled dispensing

23
Example Manufacturing Dispensing Solder
25µm bumps of 63/37 solder deposited on 35µm
pitch using Solder Jet technology
24
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 individuals medical
  requirements

25
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

26
Example Medical - Containment
Hydrophobic material forms barrier to contain
biological fluids or other fluids for tissue
preparation

• ADVANTAGE
• Automated
• Pattern retention
• Repeatable processes

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

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.

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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

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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

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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

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

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Case Study Stent Coating

• Precision stent handling system

34
Case Study Stent Coating

• Precision inkjet coating system

35
Case Study Stent Coating System
36
Dry Powder Deposition
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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

38
Conventional Powder Coating
Charging air gun
Typical powder spray system
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

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

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

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

43
Dry Powder Deposition System Considerations
44
What are Conductive Materials

• It depends on time for current to flow
• With copper not very long
• With fused quartz - sit down because youre going
  to be there a while
• Conductivity represents a continuum

45
Conductivity is a Continuum
Semi-conductive Materials
Conductive Materials
Insulative Materials

• In conductors, electric charges are free to move
• In an insulator, charges are less free to move
• Theres 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

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.

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

48
Charging of Insulative Powders

• Insulative Material Charging
• Most commonly charged by triboelectrification
• Mechanical contact/rubbing causes charges to
  exchange

Functional Powder
Carrier
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Triboelectric Series
50
Powder Charge Distribution
VOLUME (Number)
30
5
25
-5
10
15
20
Charge - ?C/gm
Wrong Sign
Low Charge
Target
High Charge
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
52
Powder Transport

• Magnetically permeable powders are most commonly
  transported via magnetic forces
• Powder can be magnetically permeable
• or
• Can incorporate a magnetic Carrier

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

54
Electrostatic Deposition Material Choices
The physics to follow
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

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

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

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

59
Tablet Coating Process Today

• Batch process
• Solvent based
• Tumble dried

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

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

62
The Solution

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

63
Deposition Applicator of Choice

• Rotating magnet DCD system
• Permanently magnetized carrier
• Both provide vigorous mixing in development zone

64
Pharmaceutical EDPD Housing
Elements Licensed from Heidelberg
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

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

67
Tablet Holder
Ejector/Electrode
Conductive Flexible Cup
Shield (reverse biased)
Vacuum Connection
68
Coating Uniformity Issues
Strong field

• 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

69
Field Collapse Process
E maximum
E
1
2
Time 0
E 0
E
3
4
Time Completion
70
Coating Uniformity Results

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

71
Continuous Process

• Section of coating drum with tablets

72
The Finished Product
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

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

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

76
Xactiv Conductive-Conductive DepositionParticle
Induction Charging Detachment via Field
Intensification
Weak Electric Field for Deposition
VA
Electric Field Intensification for Induction
Charging Detachment
Electrode structures
77
Xactiv Cond-Cond ImplementationMagnetic Brush
Deposition
Carbon Paper
Air Gap
Paddle Wheel Elevator Metering
Magnetic Brush Rotating Magnets Stationary Sleeve
Cross Mixer
78
Magnetic Brush Unit
79
Magnetic Brush Structure
80
Magnetic Brush Forces
Carbon Paper
VA
N
81
Non Contact Magnetic Brush Deposition
Carbon Paper
Electric field intensified for induction charging
detachment of PtC/PTFE blend
VA
N
82
Surrogate Tribo FixtureTheory
Enables rapid evaluation of materials,
concentrations, blend and mixing conditions.
VA
S
N
S
S
N
Motor
83
Tribo Fixture
84
PtC/PTFE on Carbon Paper
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

86
PtC/PTFE Density vs Depositionswith Tribo
Fixture(Fixed field, Blend of 60 15PtC 40
Teflon mixed with carrier)
Require 5 10 mg/cm2 for anode and cathode,
respectively
87
Q/M Percent Powder Detachment
88
Vacuum AssistedMagnetic Brush Deposition
Vacuum Plenum
Porous/Conducting Support
Carbon Paper
VA
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

90
Electrode Fabrication Process
Transport Belt with Electrostatic Grip
Powder Consolidation
Radiant Heat Sintering
Carbon Paper Feed
Developer unit

• 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

91
Linear Plate Translator Magnetic Brush
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

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

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

95
Sintering via Flash Radiant Heating
Transport Belt
Carbon Paper
PtC/PTFE
Flash Lamp Cavity
N2 ?
96
Results Surface Morphology
500x
25x
97
Results - Dispersion Uniformity
Platinum Carbon
Fluorine

• SEM from Deposited Layer

98
Results - Functionality

• Deposited 5 mg/cm2 on 4x4 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

99
Any Questions???