Advances in Printing nano Cu and Using Existing Cu Based

Manufacturing ProcessesMichael J. Carmody

Chief Scientist, Intrinsiq Materials

Why Use Copper?

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• Lower Cost than Silver.• Print on Numerous Substrates.• Reduce Electro migration - Reduce shorting of adjacent traces in

fine line and pitch patterns.• Equipment Agnostic.• World is Tooled to Process Copper: Seamlessly Fits into Established

Downstream Global Copper Based Manufacturing Processes (solder mask, soldering, plating, etc.).

Objective: Show that copper can fit into time-tested and developing electronics manufacturing processes

IM Nanoparticle Production and Formulation

Rapid Prototyping

• Process flexibility

• Process control

• Fully instrumented

Pilot PlantAnnual capacity pastes/inks: ~1

tonne

Analysis• Extensive

Scientific Testing facilities

• SEM / STEM / EDX

Inks

Screen Pastes

Application Deposition Method

Fluid Substrate Sintering Method

Bulk Factor/Adhesion

Automotive Lighting

Screen PrintInkjet Print

Paste LCP Formic Acid / Nitrogen

7X / 5B

Cu Foil Slot Die Ink Kapton Pulse Forge 12X, 10 N/cm

Wiring Harness Screen Print Paste PET Formic Acid / Nitrogen

7X / 5B

3D Conformal Parts

Optomec AJ Ink Kapton Laser 4X / 5B

Four Applications, Various Deposition Methods, Substrates, Sintering Methods, and PCB Processes

Molex ASEP Process Steps

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1. Stamp2. Mold3. Surface Pattern4. Print (Screen Print or Inkjet)5. Sinter (Heller Industries)6. Electroplate Cu and Sn7. Soldermask8. Solderpaste9. Place Components and Reflow10. Remove Electrical Connections and Test11. Remove from Carrier and Final Assembly

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Advantages of the Application Specific Electronics (ASEP) Process v Standard PCB

Package• Additive vs subtractive (saves 20 steps)

• Use Common Surface finishes like ENEPIG (Electroless Ni Electroless Pd and Immersion Au) can be used for wire bonding bare die, solderability, and connector interfaces.

• Uses far less water than standard PCB process– 20 gallons/m^2 v 400 gallons/m^2 for standard boards

• Molded plastic can be recycled (instead of thrown in a landfill)

• Lower total cost

Accelerated Life Testing-Cycling from -40˚C to 85˚C over 1000 hours-All parts passed

Under the Hood Testing (on the previous parts)-Temperature range extended to -40˚C to 110˚C-All parts passed

Automotive Testing 1. Multi-layer circuitry2. Three dimensional feature capable3. Integrated connector function4. Integrated rigid PCB functions5. Integrated flexible circuit functions6. Thermal management features7. High current carrying features can be integrated8. Could be used to combine first and second level

silicon packaging9. Fully additively manufactured which minimizes

water use10. Hermetically sealed interfaces are inherently

possible11. Continuously flow manufactured which minimizes

labor cost12. Highly automated manufacturing improves yields

and reliability13. Minimizes the need for secondary assembly

through part integration14. Validated for automotive under the hood

applications (-40 to 110 C)

Process Flow for Ultra Thin Copper Foil

Slot die coat Photonically Sinter Plate and Etch

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Peel

Str

engt

h (N

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Overlap Factor

Ave Peel as f(Overlap Factor)

We optimized peel strength as a function of Pulse Forge sintering parameters. Statistically, our best conditions averaged 9.5+/-0.6 N/cm for 18 samples.

Conditions giving the best conductivity are not necessarily best for peel strength

Etching Results

• Etch results were excellent

• Very straight side walls due to very thin base copper to be etched.

• Profilometry graph and cross section pictures show very straight side walls.

• Very important for high speed and RF Designs.

Figure 2. Optomec AJ5X System, Tilt & Rotate Trunnion.

Process Flow for Conformal 3D Printing

Optomec Jetting 808 nm Laser Test

130 micronline width

Laser Sintering Copper on KaptonNot All Applications Need Bulk

Copper Conductivity

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Resis

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Laser Power (mW)Resistance as a function of laser power at 5 mm/s scan speed

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Scan Speed (mm/s)Resistance as a function of scan speed with laser power at 300 mW

•SnPb with flux•Uniform wetting of pad•Unlike Ag pads, no savaging of metal by the solder is observed

5B ranking on Kaptonaccording to ASTM3359

Post Sinter Processing

Flex Application: Strain Gauges

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Copper strain gauge

Wheatstone Bridge Circuit diagram

•Cyclic bending over 28 mm diameter pipe (0.3% strain)•More than 10,000 flexes without signal degradation

Traditional Cable Harness vs. Printed Copper on PET

-Bulky, heavy and limited flex because of insulation -Labor intensive to manufacture

-Lighter , fewer cable ties and fasteners and more flexible. Print only copper needed.-Process is very automated

Lightweight Cable Assembly on PET

Don Novotny: DNovotny@intrinsiqmaterials.com 16

-1’ wide X 3’ long-Laminated with PET cover -10X Bulk Cu resistivity

-Able to easily change digital tooling-Inexpensive materials-No changes to standard screen printing technology required

Large area screen printing at Swansea University

Sintering in the Heller Conveyor Oven-190˚C-7.5% Formic Acid in Nitrogen-Conveyed at 5 inches / minute

Intrinsiq Confidential

A Screen Printed, Heller Sintered Prototype Circuit

Conclusions• Sintered Copper materials can be printed on low Tg Flexible

Substrates, plated and etched using conventional PCB process common world wide.

• After sintering and common overcoating, copper survives solder reflow temperatures.

• Manufactured parts with Copper can survive large, real world temperature testing (1000 hrs) and bend cycles (10,000 cycles).

• A variety of sintering conditions were used.• A variety of deposition methods were employed.

Special Thanks• Nextflex• Molex-Vic Zaderej• NovaCentrix-Vahid Akhavan• Optomec-Mike Renn and Matt Schrandt• Heller Industries-Dave Heller & Michael Barnes• Intrinsiq colleagues in the US and UK