Using Existing Cu Based Manufacturing Processes Michael J. Carmody - - PowerPoint PPT Presentation

Advances in Printing nano Cu and Using Existing Cu Based Manufacturing Processes

Michael J. Carmody Chief Scientist, Intrinsiq Materials

Why Use Copper?

• 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 Plant Annual 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 Print Inkjet 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

• 1. Stamp
• 2. Mold
• 3. Surface Pattern
• 4. Print (Screen Print or Inkjet)
• 5. Sinter (Heller Industries)
• 6. Electroplate Cu and Sn
• 7. Soldermask
• 8. Solderpaste
• 9. Place Components and Reflow
• 10. Remove Electrical Connections and Test
• 11. 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 circuitry 2. Three dimensional feature capable 3. Integrated connector function 4. Integrated rigid PCB functions 5. Integrated flexible circuit functions 6. Thermal management features 7. High current carrying features can be integrated 8. Could be used to combine first and second level silicon packaging 9. Fully additively manufactured which minimizes water use

• 10. Hermetically sealed interfaces are inherently

possible

• 11. Continuously flow manufactured which minimizes

labor cost

• 12. Highly automated manufacturing improves yields

and reliability

• 13. Minimizes the need for secondary assembly

through part integration

• 14. 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

2 4 6 8 10 12 14 5 10 15 20 Peel Strength (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 micron line width

Laser Sintering Copper on Kapton Not All Applications Need Bulk Copper Conductivity

2 4 6 8 10 12 14 200 400 600 800

Resistivity (x bulk Cu) Laser Power (mW)

Resistance as a function of laser power at 5 mm/s scan speed

1 2 3 4 5 6 7 8 9 10 5 10 15 20

Resistivity (x bulk 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 Kapton according to ASTM3359

Post Sinter Processing

Flex Application: Strain Gauges

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

• n 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

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

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