|
Mesoscale Integrated Conformal Electronics and Sensors Through Advanced Thermal Spray Methods
| Principal Investigator: | |
Prof. Sanjay Sampath
Center for Thermal Spray Research
Dept. of Materials Science and Engineering
SUNY at Stony Brook, NY 11794-2275
Tel: 631-632-8480, Fax: 631-632-7878
e-mail: sanjay.sampath@sunysb.edu
|
| | |
| Co-Principal Investigators: | |
H. Herman, R. Gambino and J. Longtin
College of Engineering and Applied Sciences
SUNY at Stony Brook, NY 11794-2275
|
| | |
| Team Members: | |
R.Greenlaw, Integrated Coating Solutions, CA
B.Wessels, Northwestern University, IL
T.Feeley, Laser Fare ATG, RI
|
| | |
| Program Sponsor: | |
Defense Advanced Research Projects Agency (DARPA)
Defense Science Office (DSO), Arlington VA
Office of Naval Research
|
| | |
| Program Manager: | |
Dr.Valerie Browning
vbrowning@darpa.mil
Dr.Colin Wood
woodc@onr.navy.mil
|
1. Executive Summary
The DARPA/ONR MICE Program at Stony Brook has the
potential of propelling thermal spray technology
into unconventional areas of applications with
revolutionary benefits. Using the unique resources
of the NSF Center for Thermal Spray Research at
State University of New York at Stony Brook, it is
planned to address both the MICE PIP and hitherto
unexplored sensor device technology. Electronics
applications will require dimensionalizing of spray
devices to enable the deposition of metals,
ceramics, cermets and polymers having sought-after
electrical conductive, resistive, insulating,
capacitive and magnetic properties. In this MICE
program, led by SUNY-Stony Brook, means of CAD-based
circuit production will be demonstrated using
appropriate materials formulations and spray devices.
THERMAL SPRAY is a directed spray process, in which
material, in either solid or liquid form, is
accelerated to high velocities, impinging upon a
substrate, rapidly building a dense and strongly
adhered deposit. In the case of ceramic deposits, it
is necessary to melt the particles, which is
achieved by either a combustion flame or a plasma
arc. The deposit microstructure and, thus,
properties, aside from being dependent on the spray
material, rely on the processing parameters, which
are numerous and complex. In recent years, through
concerted, integrated efforts of the Center and
others, significant fundamental understanding of the
process has been achieved, allowing for an enhanced
control of the process.
Thermal spray coatings (i.e., thick films > 5
micrometers) are crucial to the economical, safe,
and efficient operation of many engineering
components. Numerous industries, in recognition of
thermal spray’s versatility and inherent economics,
have introduced the technology into the
manufacturing environment. The technology has
emerged as an innovative and unique means for
processing and synthesizing of high performance
materials. The main advantages of the process are:
(1) versatility with respect to feed materials
(metals, ceramics and polymers in the form of wire,
rod or powder); (2) capacity to form barrier and
functional coatings on a wide range of substrates;
(3) ability to create free-standing structures for
net-shape manufacturing of high performance
ceramics, composites and functionally-graded
materials; and (4) rapid solidification synthesis of
specialized materials. Opportunities exist for many
novel applications in advanced materials synthesis
and deposition. The technology is rapidly becoming
the process-of-choice for the synthesis of advanced
functional surfaces, such as catalytic coatings,
dielectrics, ferrites, bio-active materials, and
solid-oxide fuel-cells. Thermal spray offers
advantages for manufacture of deposits on large area
substrates and for the creation of complex conformal
functional devices and systems.
The virtues and unique advantages of thermal spray with respect to MICE are:
- High throughput manufacturing as well as high speed direct writing capability
- In situ application of metals, ceramics, polymers or any combinations of these materials, without thermal treatment or curing; incorporation of mixed or graded layers
- Useful materials properties in as-deposited state
- Cost effective, efficient and ability to process in any environment
- Limited thermal input during processing allowing for deposition on a variety of substrates.
- Adaptable to flexible manufacturing concepts
- Robotics-capable for difficult-to access-and severe environments (portable)
- Readily available for customizing special sensor systems (prototyping)
- Green technology vis-à-vis plating, lithography, etc.
- Wide range of substrates and conformal shapes
- High aspect ratio conductors and capability for via production
- Rapidly translatable development to manufacturing (using existing infrastructure)
The proposed thermal spray approach has the
potential to introduce radically new conceptual
approaches into electronics component manufacturing.
Thermal spray offers advantage over LTCC-M and HTCC-
M multi-chip modules in that there is no need for
high firing temperatures. This will enable reduces
cycle times, minimize mismatch-related stresses,
along with the ability to package a wider variety of
materials, all at high-rate manufacturing and at low
cost.
Thermal spray techniques have been
considered for a number of years for hybrid micro-
electronics, sensors, superconductors, insulated
metal substrates and other applications. A
bibliography of available publications in this area
is appended. There has been limited success in the
past to achieve high quality functional multilayers
by thermal spray. This can be attributed to several
deficiencies, key among these being: Lack of
fundamental understanding of the process and the
ensuing process-materials-property relationships;
Absence of diagnostic tools to evaluate and to
optimize the highly dynamic processes; Insufficient
process control systems; Limited expertise in
advanced materials processing.
The capabilities of thermal spray
technology, even as recently as five years ago,
would have been uncertain for meeting the stated
MICE needs. A number of important changes have
occurred. Cost-driven application developments in
the automotive industry (cylinder bore and
automotive electrical applications to name two),
availability of sophisticated, affordable diagnostic
tools, enhanced process control and reliability,
and, finally, improved fundamental understanding
through integrated, interdisciplinary research, such
as at Stony Brook’s Center for Thermal Spray
Research. Our understanding of the process and the
ability to control material microstructures now
offer unique opportunities to synthesize functional
surfaces of a variety of complex systems. The
current technology is still limited in its
capability to satisfy the needs of MICE. The
present limitation, however, is a classic case of a
technology on the verge of a needs-driven upheaval.
Thermal spray, therefore, represents a potential
breakthrough or disruptive technology.
The successes achieved thus far in the
feasibility programs exemplify such breakthroughs.
Through a concerted effort, these developments can
be focused to yield a new approach to Mesoscopic
Integrated Conformal Electronics, leading to broad-
based impact in hybrid electronics manufacturing
(e.g., large ceramic substrate devices), an entire
class of thick film sensors, sensor systems and
embedded sensor concepts. Other benefits include
enhanced application of thermal sprayed functional
surfaces and high definition thermal spray systems.
Key issues in materials properties must be
overcome to meet these goals: e.g., an understanding
and control of defect structures, stoichiometric and
composition control, non-equilibrium phase formation
and selection, residual stresses. These issues are
being addressed extensively within the Center for
Thermal Spray Research, providing unique
opportunities for the DARPA MICE application program.
Our Vision for Direct Write Thermal Spray is:
- A thermal spray based direct-write tool for meso-electronic multilayer deposition for rapid prototyping, lean and mass manufacturing
- Synthesis and development of high volume sensor applications, both as sensor systems as well as embedded sensors for use in harsh environments
- Breakthrough extension of thermal spray technology through the development of high definition thermal spray systems.
Thermal spray MICE/Sensors development can:
- Introduce novel concepts into the electronics industry with a focus on embedded and add-on sensor fabrication
- Connect embedded sensors to the “outside world” through appropriate circuitry
- Apply protective coatings on sensors for use in harsh environments.
2. Accomplishments of the Feasibility Efforts
The Key Goals of MICE Feasibility efforts have been:
- Demonstrate proof-of-concept MICE using Direct Write Thermal Spray Technology to deposit materials for base dielectric, conductors, capacitors, ferrites and resistors
- Develop materials functionality and relationships to processing
- Show pathways to achieve fine features
- Conceptualize framework for a thermal spray based MICE tool
- Develop sensor systems and embedded sensor concepts
- Develop means for fabrication of a prototype functioning sensor using thermal spray MICE.
Table I identifies the key materials goals
and associated results. The results indicate
substantial promise for thermal sprayed electronic
materials deposition. The activities of this phase
also provided a framework for addressing process-
structure-property relationships for various
functional materials.
2.2. Summary of MICE Feasibility
Deliverables and Milestones:
- The program goals targeted 500 micrometer lines for dielectrics, capacitors and resistors. 300 micrometer line-widths of ceramics were achieved.
- 100-200 micrometer conductor traces were targeted for this phase with pathways to achieve 20 micrometer goal. We have demonstrated 150 micrometer line-width with 10-75 micrometer height having a vertical edge profile. Preliminary results indicate that 50 micrometer lines can be fabricated.
- Variety of high quality functional materials have been fabricated and tested.
- Varierty of electronic and sensor devices have been fabricated and tested.
- A conceptual framework for a direct write MICE thermal spray tool was proposed and key system aspects were identified and construction of the tool is in progress.
- Model-based design and torch scaling were demonstrated, these results being used to design and fabricate a prototype.
|
