advances in printing nano cu and using existing cu based ... michael... · advances in printing...
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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
1 2 3 4 5 6 7 8 9 10 11
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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0 5 10 15 20
Peel
Str
engt
h (N
/cm
)
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
12
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0 200 400 600 800
Resis
tivity
(x b
ulk
Cu)
Laser Power (mW)Resistance as a function of laser power at 5 mm/s scan speed
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0 5 10 15 20
Resis
tivity
(x b
ulk
Cu)
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: [email protected] 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