The merger of micro and nano, chemical, and other sensors with micro- and nano-electronics could mean disruption ahead.

Consumer and professional electronics are still evolving rapidly; the need for lower cost, higher speed, more memory, better displays and smaller form factors combined with wireless connectivity, new functionality and longer battery life in handheld devices are forcing many traditional materials and systems “against the stops.”

Electronics system miniaturization for mobile computing, communication and sensing will drive a new generation of low-cost packaging technologies over the next decade. Multifunctional integration, ultra small form factor and low cost will be the defining characteristics of next-generation packaging. This new packaging technology will interface with integrated or embedded active and passive components, cooling structures and advanced interconnect structures in ultra-thin silicon and organic type substrate platforms. Chip and package co-design and considerable integration of digital, RF, optical, sensing and biological functions in 2-D and 3-D architectures will be realized. These technologies will need advanced materials with enhanced electrical, thermal and thermo-mechanical properties, and advanced manufacturing processes.

The 2007 iNEMI Roadmap1 identified a number of key areas where rapid development or discontinuous change may be required to meet these needs. The iNEMI research priorities recommended three areas for action:

Innovative packaging for gigafunctional system-in-package (SiP). Traditional interconnections of surface-mounted discretes are being changed to ultra-fine-pitch interconnections connecting embedded ultra-thin film components on ultra-thin silicon and organic type substrates. The package integration will evolve into system integration, leveraging the system-on-chip, wafer-level packaging and embedded passives and actives on organic substrate technologies. Convergent micro- and nano-systems will have not only digital and portable wireless electronics, but also bioelectronic functions. These electronics and bioelectronics devices, advanced interconnects, batteries, thermal solutions and other user interfaces such as connectors and cables can lead to multifunctional systems in the short term and more integrated gigafunctional systems in the long run. This SiP concept integrates disparate technologies to achieve multiple system functions in a single package, while providing an ultra-small form factor.

Materials and reliability. Materials continue to pace the introduction of packaging technologies to meet the major manufacturing requirements of low cost through increased modularity, integration for smaller size, and higher bandwidth for more functionality. In addition to these product-specific attributes, general require­ments for environmentally friendly materials systems (e.g., bio-based polymers) use low-energy processes. While traditional technologies have focused on materials systems for electronic performance, future materials requirements will need to embrace optical, mechanical, and chemical performance for electro-optical, microelectromechanical systems (MEMS), chemical and biosensor systems, respectively. Advanced fillers for nanocomposites and nanoengineered materials with property improvements not possible with micron-sized fillers offer the promise to meet some of these enhanced performance requirements. These property improvements include low CTE with high toughness, high electrical conductivity with low thermal conductivity (high ZT), and high compliance with high current carrying capability.

Several technologies may impact material packaging trends in the near and mid-term. In addition to shrinking the IC with higher density PWBs, embedded passives (resistors, capacitors and inductors) and embedded active devices lead the drive toward small size. A key goal is higher dielectric constant materials to produce embedded passives for de-coupling capacitors. Innovative designs and special types of organic substrate materials could also give high Q inductors. Solder systems have migrated to higher reflow temperature ranges due to the drive for Pb-free solder systems, placing severe thermal loads on the existing material systems as they traverse the reflow zones.

Underfill processes, which improve mechanical performance of parts soldered to the PWB, increase assembly time, leading to increased assembly cost. To reduce the delays associated with underfill assembly for ICs or semiconductor packages, underfill materials will be pre-bonded or will be thin films applied to the PWB by pick-and-place machines. As alternatives to solder attach, conductive adhesives (liquid or thin film) will become more common for low-temperature processing and fine-pitch assembly, assuming they can satisfy the bandwidth requirements for higher performance systems. Self-assembly methods are also evolving to address the challenging assembly needs of ultra-thin small dies in large volume. A number of innovative options are being pursued in the development of reliable fine-pitch interconnect materials and assembly processes.

Printed electronics will develop in the longer term. Produced on flexible substrates and using conductive, dielectric, semiconductor, and light emissive inks, these materials have the potential to transform segments of the electronics industry. Innovations will be needed for existing material systems to address ink sensitivity to humidity, oxygen and light.

Sensors. The rapid acquisition, processing and action resulting from sensor data (mechanical, acoustic, thermal, chemical, seismic, environmental, biological, etc.) will become critical for many uses in future years (homeland security, industrial monitoring, aging populations, quality of life, etc.). Intelligent integrated sensing and control systems are migrating from islands of automation to interconnected solutions, and subsequently to intelligent self-managing highly scalable systems (i.e., autonomous active control and monitoring systems). This evolution requires coordination and leverage across multiple technologies such as sensing, monitoring, control and communications. Sensor technologies, management tools and gateways will play a central role in enabling the higher level of integration needed in the development of these new intelligent sensing and control systems. Beyond these sensor fusion elements, architectural considerations are required to coordinate this evolution to address scalability issues such as performance, global universal object identification, system management and security. These large sensor networks will require unique solutions in the acquisition, transmission and processing of the extensive amount of information gathered for robust networks.

Sensor network development involves deployment of the sensors and the network elements to collect and transmit data for analysis and action. These sensors and their local processors and communication function may take the form of a SiP. An increasing number of these sensors are realized using micromachining technologies in the form of MEMS devices. Thus, a packaging base is needed that can support mechanical, acoustical, thermal, chemical, seismic, environmental and biological sensors, as well as optical and RF communications. It is important to identify the correct number of nodes and sensors needed to get the most accurate information at the lowest possible cost. The networks are likely to have a multiplicity of sensors, and it’s vital to determine the number and placement of the sensors within the “network field.” Redundant sensors provide more accurate information; however, with the large amount of data that can be collected from deployed sensors, it is important to identify how and where to fuse the data.

Secure self-organizing wireless nodes will form the basis for new networks and will require some localized signal processing capability. Ultra-low-power IC designs, mixed-signal module/SiP designs, sensor packaging and integration technologies will generate many new innovation options. Data from the network of sensors will be transmitted to redundant gateway devices, which will have the processing power to determine the relevance of the data based on field conditions. The gateway devices will store, analyze and relay the data as needed. This transmitted data would be used to make appropriate decisions on what actions need to be taken. The number and type of sensor nodes deployed will determine the processing power of the gateway device. The sensor networks also need to be insensitive to environmental conditions in their deployment.

Nanotechnology: Strong Implications

One potential “technology” for addressing these three areas is nanotechnology, particularly new materials based on nanoparticles. Most applications of nanotechnology are still in the pre-commercial stage and will need development not only of products but also of modeling techniques and metrologies. Products are being developed and commercialized in large and small companies with strong nanotechnology initiatives.

Nanotechnology in its various forms has strong implications for the competitiveness of the electronics industry. The combination of significant nanotechnology R&D with technology transfer obviously represents business opportunities. Nanoscale materials are already well represented in the electronics industry today, including nanocomposites and nanostructured packaging materials, sub-100 nm IC structures, and thin-film giant magneto-resistive (GMR) read heads for high-density disk drives. Nanotechnology advances will contribute a number of products and processes that could be especially relevant to electronic processes and products, ranging from the extremely long range and innovative to the short range and drop-in, including:

• Quantum computing using “peapod structures” based on carbon nanotubes (CNT) or Bose-Einstein atomic clusters (long term).
  
  
• DNA strand self-assembly of electronic structures (long term).
  
  
• Transistors based on CNT or GMR layered structures (long term).
  
  
• Mixed nano and MEMS sensor technology (medium term).
  
  
• Plasma display technology based on CNT emitters (medium term).
  
  
• Advanced fillers for nanocomposites and nanoengineered materials with property improvements not possible with micron fillers, such as low CTE with high toughness, high electrical conductivity with low thermal conductivity (high ZT), and high compliance with high current carrying capability (short term).
  
  
• Nano-enabled solders and printable electronic structures using nano-sized metals, particularly silver and copper (short term).

Commercialization of these products will depend on cost and performance when substituting for existing systems, and on the dynamics of new market creation. The iNEMI Roadmap process will continue to monitor advances in nanotechnologies and assess how these advances meet the electronics industry’s R&D needs.

Conclusions

As we move beyond the digital convergence of electronics products, we anticipate the merger of micro and nano, chemical, mechanical and biological sensors with micro- and nano-electronics for disruptive innovations in many areas. In some cases, the disruptive technologies may also find application by being embedded in conventional product embodiments. As an example, nanoparticle fillers may enhance select properties of existing polymeric materials. These applications will likely result in new opportunities to extend the life of current materials and manufacturing infrastructure, enabling them to deliver enhanced device or component functionality. Breakthroughs may take the form of disruptive technologies that supplant existing technologies. Examples of these are quantum computing systems, molecular electronics and spintronics replacing CMOS semiconductor technology. Others may be radically new applications, such as sensor and drug delivery systems that detect emerging disease in the body or treat existing conditions.

The industry restructuring over the past decade from vertically integrated OEMs to a multi-firm supply chain has resulted in a disparity in R&D needs versus available resources. Critical R&D needs exist in the middle part of the supply chain (IC assembly services, passive components, EMS assembly) (Figure 1), and yet these are the firms least capable of providing the resources. A partial solution has been the development of vertical teams to develop critical new technology while sharing costs. The entire industrial supply chain, universities, research institutions and governments need to not only create innovative technologies, but also creative solutions for financing the R&D base that generates these innovations. This must be done in a way that deals with IP in a distributed fashion (rather than the traditional single-company approach) so that ROI for the R&D investments are fairly apportioned, thus encouraging sustainable innovation.


Au. note: This article is based on information from the 2007 iNEMI Research Priorities, available at http://thor.inemi.org/webdownload/RI/iNEMI_2007_Research_Priorities.pdf.

References

1. 2007 iNEMI Roadmap, March 2007.

Alan Rae is director of research at iNEMI (inemi.org) and vice president of innovation at NanoDynamics Inc. (nanodynamics.com); arae@nanodynamics.com. Robert C. Pfahl is vice president of operations and Charles Richardson is director of roadmapping at iNEMI.

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