Research & Development

ACI Materials is continuously developing cutting edge functional materials to offer superior performance to existing product types and fill gaps in available materials. ACI is also seeking joint partnerships with common interests.


ACI Products


ACI New Product Roadmap

Future Materials
in Development

ACI is currently exploring a range of functional materials including:
  • Concentrated dispersions and liquid masterbatches of high aspect ratio fillers such as CNFs, CNTs, BN, graphite, etc.
  • Low dielectric loss substrate materials for 5G and beyond
  • Strengthening of 3D printable polymers using high aspect ratio nano fillers
  • Assembly materials for use with additively manufactured flex circuits and flexible hybrid electronics
  • And more


ACI Products

Semi-Sinterable and Sinterable Conductors

ACI Alchemy Conductive Inks

ACI Materials has developed a new series of semi sinterable and sinterable conductive inks which demonstrate a unique combination of capabilities
  • Lower sheet resistance than PTF, nanoparticle, and metal complex based inks
  • Faster cure times than traditional nanoparticle based sinterable inks
  • Nano like volume resistivity (conductivity), but in less time
  • Superior hard crease survivability compared to even PTF inks
  • Allow high resolution printing without compromising resistivity and sheet resistance
  • Enables reflow soldering using solder pastes
  • Thinner EMI shielding coatings

ACI Products


TechBlick
Printed, Hybrid, Structural, & 3D Electronics

ACI Alchemy Conductive Inks Enabling
Next Generation Flexible and 3D Electronics

Michael Mastropietro
Vice President of Engineering - ACI Materials

Background

Percolation Conductors vs
Sintering Conductors


Challenges of Percolation Conductors


Currently the conductive inks used commercially are of the traditional polymer thick film (PTF) silver type. These are "percolation" type conductors comprised of conductive fillers dispersed at high loadings in to thermoplastic polymers that have been dissolved in a solvent. After printing, drying forces the solvent out, shrinking the polymer phase, forcing the conductive fillers into near contact. The upside is good adhesion due to the amount of polymer wetting the substrate interface. The downside is the polymers and organics stabilizers on the particles create contact resistance diminishing electrical performance, and even best ones only achieve volume resistivity on the order of lead (Pb).


Next Level - Sinterable Conductors


In order to overcome the interparticle contact resistance inherent of PTF conductors, sinterable conductors were introduced over the last 20 years. Under the right conditions (higher curing temps or longer cure times, typically thinner film thickness) they can provide conductivity a step above percolation conductors; even close to bulk silver. This allows silver usage and thus cost reduction. However, it is very difficult to formulate them with enough resin to wet the substrate well, but without so much it doesn’t interfere with sintering and thus improvement to resistivity. It is also challenging to drive sintering at equivalent temperatures to which PTF conductors can be dried. Therefore, although these conductors have been commercially available for decades, and perform well in a lab, few have been used in commercial electronic devices.


ACI's Inks of the Future
Semi-Sintering or Hybrid Conductors


ACI’s Alchemy Conductive Inks offer the ‘best of both worlds’. They contain enough resin to achieve perfect adhesion on typical substrates like PTF products, and can be cured in similar times in many cases. However, the particles sinter resulting in resistivity similar to most nanoparticle and complex based inks, but also at much higher film thickness. The Alchemy name comes from the analogy that one could directly replace their current material that performs like lead with something performing much closer to gold. This also allows lower usage of silver and thus cost reduction as nano inks typically claim.


Alchemy Series Benefits

Performance

Lower Volume Resistivity in Less Time

  • Alchemy Inks achieve lower (up to 10x) volume resistivity than competing PTF materials.
  • They achieve their ultimate volume resistivity faster than other semi-sinterable and nanoparticle based screen inks.
  • Rheology for a diverse range of deposition methods ranging from high viscosity pastes for microdispense and screen printing to fluid formulation for spraying EMI shielding.
  • ACI is seeking development partners to optimize its fully sinterable pastes for die attach applications.
  • Performance

    Lower Sheet Resistance & Faster Cure Times
  • Alchemy inks have very fast cure kinetics compared to other sinterable formulations thus allowing faster cure times.
  • Rheology’s and solids contents appropriate for a range of screen meshes yielding the ability vary film thickness from a couple microns to thick busbars for high current or power density applications.
  • Very low sheet resistance compared to traditional polymer thick films.
  • Applicable for high performance flexible hybrid electronics and more.
  • Developed in partnership with Semi, FlexTech and Army Research Laboratory

  • Performance

    Superior Hard Crease Survivability

  • Good flex and crease ability requires good substrate adhesion, and this has limited many sinterable conductors. Many nano inks that show good adhesion at submicron thickness have poor adhesion when printed thicker.
  • ACI has demonstrated a formulation that survive creasing when PTF formulations can’t; and it isn’t magic. Survivability is achieved by being able achieve equivalent sheet resistance to PTF inks at much thinner film thickness, since minimum flex/crease radius is typically inversely proportional to conductor film thickness
  • Formulations optimized in partnership with Semi, FlexTech and Army Research Laboratory

  • Performance

    EMI Spray Shielding Coatings

  • Thinner coatings <5 microns possible with equivalent EMI performance
  • Shorter processing times or lower temperatures than competing products
  • Solvent based and aqueous based formulations
  • Alchemy Inks have a high degree of formulation latitude
  • Fluid dispersions for straying without defect due to small nano particles
  •  

    Performance

    Enables Reflow Soldering

  • Both semi-sintering and full sintering formulations allow good wet ability by solder pastes during reflow soldering
  • Solderability should allow use of screen printing for additive manufacture of PCB and FPC
  • Enables additive manufacturing to circuit boards


  • Note: Developed in partnership with Semi, FlexTech and Army Research Laboratory - (see below)

    Performance

    High-Resolution Printing Without Compromise

  • Making high density interconnects requires high resolution
  • Early Alchemy Inks results are showing great promise for producing compact electronic devices
  • Very narrow traces allows packing in small spaces
  • ACI seeking development partners to help speed progress and share feedback
  • Not giving up electrical performance as found in traditional polymer thick film inks
  • Cost Reduction

    Alchemy Inks Reduce Cost Per Device

  • Circuits must meet the designs resistance specifications
  • The ink cost per device is a function of ink resistivity, solids, and cost per kg
  • A more expensive ink can cost less in use
  • Developed in partnership with Semi, FlexTech and Army Research Laboratory
    This material is based on research sponsored by Army Research Laboratory under agreement number W911NF-19-2-0345. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon.  The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of Army Research Laboratory ( ARL) or the U.S. Government.


    Alchemy Series In Use

    Flexible Hybrid Electronics

    High Current Density Busbars

    “From automotive to industrial equipment, transparent heaters made from CHASM’s CNT Hybrid material are generating significant excitement with product innovators across many industries and ranging in size from a few square inches to many square feet,” said Ken Klapproth, Chief Marketing Officer, CHASM Advanced Materials, Inc. “Having a range of compatible materials at our disposal such as ACI’s Alchemy conductive inks gives us the versatility we need to produce the best flexible printed electronics customers will never see.”

    —Images courtesy of CHASM

    3D Printing

    Enabling Unique Form Factors

  • Fully functional cylindrical acoustic sensor platform equipped with Bluetooth communication
  • Digitally manufactured circuits reduce prototyping time
  • NScrypt 3Dn systems enable manufacturing fully functional, cylindrically printed circuits with embedded components
  • 3D printed circuit structures allow for volumetric savings in areas where traditional PCB’s fall flat
  • Higher tip to substrate height assists in printing traces on 3D printed substrates with surface roughness
  • Less slump makes the ink easier to print for finer traces and spaces
  • —Image courtesy of NScrypt

    Die Attach

    Sintering Pastes for Die Attach & More

    RD0090x Sintering Pastes

  • Microdispensed from nozzle 57 um ID/169 um OD nozzle on Voltera V-one desktop extrusion printer
  • No leakage on stoppage 
  • Differentiation & Value Add

  • Polymer free system maintains proper low slump screen and dispense print rheology
  • Complete through film sintering at high film thickness 50+ µm
  • Potentially shorter cure times than competitive materials
  • —Image courtesy of Voltera

    ACI's Cavitation Platform


    Carbon
    Nanotubes



  • Graphene nanotubes for superior performance in EV batteries
  • Graphene nanotubes for automotive primers

  • ACI Products

    The Unbundling Challenge


    Pre-cavitation mixing samples show large bundles of chords of SWCNT. Chords widths rang in the 50-200nm (nominal diameter of individual SWCNT ~2.5nm, so 20-80 tubes wide). Due to the immense surface area of the SWCNT and the Van der Waal attractions, the SWCNT have a propensity to bind together strongly. This makes it very challenging to unbundle the chords, without causing significant damage to the SWCNT aspect ratio. The SEM has a limited capability to assess the nano structure of the chords, which can be revealed using other imaging techniques that ACI Materials currently does not have. It is also uncertain that dried films would be able to remain un-aggregated as the solvent vaporizes. It is likely that much of the CNT content would stick back to each other, due to the ultra-high surface area.


    Cavitation - The Unbundling Solution

    Through controlling the cavitation processing parameters, we are able to effectively unbundle CNTs while keeping their aspect ratio intact. We can control the amount of unbundling that occurs so that the outcome is a balance of targeted Volume Resistivity and Sheet Resistance, as well as desired rheological properties.

    Viscosity & Volume Resistance

    Through ACI Material's precise control of cavitation processing parameters, it is able to effectively unbundle CNTs while keeping their aspect ratio intact. The process can control the amount of unbundling and dispersing that occurs, so that the outcome is an optimal balance of volume resistivity and desired rheological properties.

    The graph demonstrates how processing control allows for ACI to choose which conditions give the best electrical performance at an appropriate viscosity for the given application. These volume resistivity values are evaluated from dried, stencil printed films of pure SWCNTs at various processing conditions.

    ACI Masterbatch Concentrates

    Masterbatch
    Concentrates

    MasterBatch (concentrates) of High Aspect Ratio (HAR) particles
    • ACI disperses high value functional fillers in high concentrations which can be used as additives to enhance performance.
    • ACI Masterbatches contain materials that are difficult to effectively disperse such as Carbon Nanotubes and Boron Nitride. We are able to disperse and exfoliate challenging materials in a variety of solvents and polymers.
    • The ACI dispersion technology offers superior control of top size particles through effective elimination of large agglomerates.
    • Contact us if you would like to discuss dispersions of high value, difficult to disperse functional fillers.

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