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Aerosol Jet® Printing of A Silver Epoxy Conductive Adhesive for High Density
Applications
Kurt Christenson and Michael Renn - Optomec, Inc.
Donald Giroux - Resin Designs, LLC
Daniel Blazej - Assembly Answers, LLC
IMAPS New England SymposiumBoxborough, MA
May 8, 2012
May 8, 2012 IMAPS New England Symposium Page 2
Who Are The Players?• Optomec - Equipment Company Based In
Albuquerque, NM Focused On Additive Manufacturing– LENS (Laser Engineered Net Shaping) 3D Printer– Aerosol Jet® Printer
• Resin Designs - Adhesives Company In Woburn, MA Producing Custom Formulations For Many Electronic and Industrial Applications
• Assembly Answers - Manufacturers Representative Providing Sales and Marketing Services For Resin Designs
May 8, 2012 IMAPS New England Symposium Page 3
Drivers for Collaboration
• Identified Needs For Conductive Adhesive That Can Be:– Dispensed In Small Volumes, Creating Dots 0.001” - 0.002” In
Diameter For Small Components and Thin Bond Lines– Dispensed In Recessed Areas And On Different Height
Substrates With Non-Contact Nozzle, Standoff Up To 1 cm– Used For Bonding Small Devices Requiring High Electrical and
Thermal Conductivity
• Push “Pixel Density” from ~100 DPI To ~1000 DPI And From 2D to 3D
May 8, 2012 IMAPS New England Symposium Page 4
Optomec Aerosol Jet Technology
• Material Aerosolized and Mixed With Carrier Gas In Atomizer
• Aerosol Concentrated In Virtual Impactor And Excess Gas Removed
• Material Stream Exits At Deposition Head And Patterns Created With Shutter (Not Shown)
May 8, 2012 IMAPS New England Symposium Page 5
Aerosol Jet Process Movie
Video May Also Be Seen Here
May 8, 2012 IMAPS New England Symposium Page 6
Aerosol Jet Is Not Ink Jet!
May 8, 2012 IMAPS New England Symposium Page 7
Unique Dispense Technology Needs Unique Adhesive Technology
• Silver Particles Need To Be Nanometer Sized– Conventional Die Attach Adhesives
Use Multimicrometer Sized Particles
• Silver And Resins Must Maintain Homogeneous Distribution In Micrometer Sized Droplets
• Resins Must Be Stable For Processing And Long Work Life
Conventional Silver PasteParticle Size Distribution Before and After Aerosol
Jet Deposition
May 8, 2012 IMAPS New England Symposium Page 8
Development Challenges
• Epoxy System Selected As Core Adhesive– Critical Modifications Made Over Course Of Project
• Separation Of Silver and Resin In Aerosol An Early Stumbling Block– Overcome With Modifications To Both Silver and Resin– Important To Understand How Aerosol Is Created And
Maintained
• Maintaining Stoichiometry of Resin and Hardener In Aerosol Is Critical For Optimum Properties
May 8, 2012 IMAPS New England Symposium Page 9
Aerosolizing Adhesive!
• Collison Nebulizer Creates Aerosol– Carrier Gas @ 20 PSI Aspirates Liquid
Suspension of Silver and Resins– Spray Is Directed Onto Wall of Jar– Small Drops Recoil, Producing Aerosol
That Exits Through Outlet Tube
• Silver Adhesive System Designed To Stay Intact Through This Process– Choice Of Solvent Is Critical
May 8, 2012 IMAPS New England Symposium Page 10
Printing Adhesive• Test Pattern Is 10 x 10 Array Of 10 mil (250 µm)
Squares– Thickness Range Is 10 - 30 µm– Built Up From Individual Drops <5 µm In Diameter– Cross Section Is Isosceles Trapezoid
Not:
May 8, 2012 IMAPS New England Symposium Page 11
Producing A Single Square
QuickTime™ and aJVT/AVC Coding decompressorare needed to see this picture.
Click On Each Picture To See Video (May Not Show On All Systems)
May 8, 2012 IMAPS New England Symposium Page 12
Process / Handling Characteristics
• High Velocity Jet (100 m/sec) Precisely Places Adhesive– Solvent Removal Facilitated With Heated
Substrate At 60°C
• Cure 60 Minutes @ 150°
• Work Life > 1 Week
• Store 6 Months @ -10°C
May 8, 2012 IMAPS New England Symposium Page 13
Electrical Properties• Five Line Patterns On Alumina Substrate• Line Width = 130 µm, Height = 15 µm• Cured 60 Minutes @ 150°C• Linear Response, Resistivity = 5 x 10-5 Ω-cm
0
5
10
15
20
25
30
35
40
45
0 2 4 6 8 10 12 14 16
Line Length (cm)
Resistance (ohms)
May 8, 2012 IMAPS New England Symposium Page 14
Adhesion Properties
• Lap Shear Between Aluminum Plates Is 2000 PSI
• Die Shear Of 15 Mil Tabs On Gold Is 3000 PSI
• Cohesive Failure In All Cases• Comparable To Standard Die
Attach Epoxies• Meets MIL-STD-883, Method
2019 Requirement of 882 PSI• Tg ~ 100°C
15 mil Square Kovar Tab On Needle Dispensed
Nanoparticle Silver Epoxy
May 8, 2012 IMAPS New England Symposium Page 15
Technical Status
• Basic Formulations Established For Aerosol Jet and Narrow Gauge Needle Dispense– Minor Modifications For Handling Optimization May Occur
• Additional Characterization In Process– Thermal Conductivity
• Expecting High Value Based On High Silver Content
– Storage Modulus– Ionic Content– Outgassing– CTE– Work and Storage Life
May 8, 2012 IMAPS New England Symposium Page 16
Summary• New Conductive Adhesive Material Developed For Use
With Novel, Non-Contact Dispense Technology– Significant Benefits Realized In Creating Small Features With
Laser-Like Control On Varying Height Surfaces– Unique Adhesive Characterized By High Loading Of Nanoparticle
Silver In Epoxy Resin
• Optomec Aerosol Jet Systems Are Commercially Available– Applications Lab In Minnesota For Customer Support
• Resin Designs Nanoparticle Silver Epoxies Available For Sampling– Aerosol Jet– Narrow Gauge Needle
May 8, 2012 IMAPS New England Symposium Page 17
Company Links and E-Mail
• Resin Designs, LLC: www.resindesigns.com– Don Giroux: [email protected]
• Optomec, Inc.: www.optomec.com– Kurt Christenson: [email protected]– Mike Renn: [email protected]
• Assembly Answers, LLC: www.assemblyanswers.com– Dan Blazej: [email protected]
