Research 2023-2024

The IEEC values research as a means to create connections and to open future possibilities in the area of electronics packaging.

  

Pooled Research Projects

Every year, we provide what we call "seed-funding," to propel research opportunities in the direction of capacity building and problem-solving for faculty members in academia.

Skilled researchers partner with industry members to meet real-time project needs of companies. That is, whether you are a chemist, physicist, or mechanical engineer, to name a few, members of all fields carry expertise that is integral in catapulting the metrics of success for projects to reach new heights.

Below are the abstracts of the selected 2023-2024 Pooled Research Projects-a partnership between faculty and mentor companies.

2023-2024 Pooled Research Projects

• Laser Fabrication of Photonic Devices in Flexible Glass and Tomographic Characterization - Bonguu Shim

  In this proposed research, we will

  1) use femtosecond laser micromachining (FLM) to fabricate photonic devices such as waveguides and photonic lanterns in Corning® flexible glass and

  2) develop computed tomography (CT) to visualize and measure the 3-D index profiles of laser-fabricated photonic devices.

  The proposed CT scan should provide an excellent control knob for FLM parameter control such as focusing geometry, laser energy, etc.

• Application Relevant Electromigration Testing of Large Eutectic Sn-Bi Joints - Peter Borgesen, Eric Cotts
  The mean time to failure during cyclic current stressing of near eutectic Sn-Bi solder joints will be characterized as a function of temperature and current density. Selected samples will be subjected to heat treatment before current stressing, so as to significantly change the solder joint morphology (increase Bi precipitate size, react all of the Sn to form intermetallic compounds).
• Conformal Polymeric Films Manufactured Using Field-Guided Electrospray Deposition - Paul Chiarot

  Thin polymeric films support a broad range of applications in electronics manufacturing and packaging, since they can serve as a dielectric layer, optical waveguide, or can provide electrical isolation and corrosion resistance.

  The objective of this proposal is to establish the process-structure-function relationship for the electrospray deposition of polyimide. Electrospray deposition is a low-cost additive manufacturing technique for creating films with thicknesses ranging from 10s of nanometers up to 10s of microns. We seek to build high-κ dielectrics, that can conformally coat a target surface with high adhesion and etch-free patterning.

• In-Situ X-ray Microscope Study of Thermal Interface Material, Application, Evolution and Defect Formation - Scott Schiffres, Bahgat Sammakia

  Thermal solutions, especially regarding heat sinks and thermal interface materials, need benchmarking under realistic heating and stress patterns. This project will reveal details about how TIMs change morphology and how defects in TIMs nucleate and grow using 3D X-ray imaging of the TIMs (~10 nm resolution) combined with in-situ characterization of thermal resistance. This will allow a more accurate understanding of the changes occurring in the material and a better estimation of the thermal resistance of the TIM1 layer for the in-situ tests. We will test with heterogeneously packaged chips.

  Our objective is to utilize a micro-CT imaging device to understand the change in the distribution of the TIM1 layer during the testing and use it to validate and support the findings from the thermal test vehicle that we have created from commercially available packages using software tools available. The effect of TIM dispensing, the initial distribution of the TIM, and the final state after the testing will be recorded for multiple samples. Input from industry on materials and deposition methods will be considered. We would also gladly accept samples from member companies to test.

• Development of Bimodal Nanoalloy Inks and Pastes with High Performance - Chuan-Jian Zhong

  Metal nanoparticle inks or pastes have been widely used in printed electronics, demonstrating many advantages over traditional photolithographically-printed electronics. A key knowledge gap is the control over both the interconnection (or merging) of the nanoparticles from the ink/paste and the adhesion (or nanoparticle-substrate interaction) of the sintered nanoparticles on the substrate. This gap is not only reflected on surface printing in single-layer electronics, but more seriously reflected by through-hole filing in multilayer electronics. The goal of this project is to develop the concept of a bimodal nano metal/alloy ink/paste to address the knowledge gap. This concept involves a combination of sintering theories, interparticle necking initiated sintering (INIS) and surface-mobility mediated sintering (SMMS), where INIS facilitates interconnecting the nanoparticles while SMMS promotes the nanoparticle-substrate interaction or adhesion. The bimodal nano metal/alloy inks/pastes not only facilitate both SMMS and INIS processes, but also reduce the sintering temperature.

  Key objectives in the project period include:

  1) synthesizing and formulating the bimodal nano metal/alloy inks/pastes;

  2) determining the two sintering mechanisms and factors controlling the sintering processes on different substrates, and; 

  3) establishing a scalable route to the optimal ink/pastes for the printed electronics applications.

• Modeling Current Flow through Copper with Surface-Deposited Metallica and Intermetallic Barrier Layers - Manuel Smeu
  Building on our recent work modeling current flow through copper with rough surfaces, we will now explore the effects barrier layers have on electron flow through Cu interconnects. We will use a combination of density functional theory (DFT) and the non-equilibrium Green’s function technique in conjunction with DFT (NEGF-DFT) to investigate the resistance, conductance, and current-voltage profile of Cu with metallic and intermetallic barrier layers deposited on the interconnect surface. From these data we will be able to identify if a rough barrier layer deposited on a pristine Cu interconnect reduces surface scattering and consequently offers performance benefits when compared to a pure Cu interconnect with a rough surface. Through these efforts, we aim to identify key tradeoffs that our industrial partners can leverage to produce higher-quality devices.
• Additively Manufactured Copper/Nickel Bi-metal Structures with Tailored Strength and Conductivity for Electronics Applications - Fuda Ning

  Bi-metal structures show great promise in the electronics industry due to the complementary properties achieved by dissimilar metal alloys. Traditional manufacturing technologies for bi-metal parts pose challenges in design, process flexibility, manufacturing cost, and efficiency.

  In this proposal, extrusion-based sintering-assisted additive manufacturing (ESAM) will be leveraged to create a first-of-its-kind copper/nickel functional component with high thermo-electrical conductivity and high strength that can be used in the harsh working environment for thermal management purposes. We will develop a robust and reliable ESAM process, understand the underlying mechanisms of copper infiltration and nickel sintering, and test the thermo-mechano-electrical properties of functional, bi-metal structure prototypes. The physics-informed computational modeling through the discrete element method and computational fluid dynamics will be established for the process simulation and prediction. Experiments will be performed to understand the process and behavior of the as-sintered components. The performance of the manufactured components will be comprehensively quantified and evaluated through a variety of mechanical, thermal, and electrical tests. If successful, this project will contribute to a new manufacturing paradigm of strong and conductive bi-metal structures for thermal management applications.

• Modeling Thermal Propertices for Novel Packaging Materials from First Principles - Manuel Smeu

  With contemporary packaging solutions continuing to increase device density, the need to effectively manage heat and find thermal solutions in dense circuit packaging becomes increasingly important.

  To address this issue in advanced architectures, we will employ density functional theory (DFT) to computationally derive three important thermal properties for a variety of novel packaging and interfacial materials: phonon band structures, lattice thermal conductivity, and coefficients of thermal expansion (CTE).

  We are chiefly interested in investigating these three thermal properties for materials including but not limited to WVTi alloys, doped transition metal dichalcogenide (TMDC) multilayers, and Cu-on-Si3N4 substrates. We will compare the thermal characteristics of these novel materials to more common packaging materials such as silicon and liquid crystal polymers (LCPs).

  Through this investigation of thermal conductivity and CTE, we aim to provide key thermal insights into next-generation interfacial materials to our industry partners.

• Conformal Coating Process Optimization based on a Sequential Multi-Stage Model - Chelsea Jin

  The dispensing coating process plays a crucial role in the production of electronic components, particularly printed circuit boards (PCBs).

  To achieve the desired coating quality, it is vital to control several parameters during the dispensing coating process. The coating quality is typically evaluated based on coverage, thickness, and the presence of defects. Existing studies mainly focus on physics-based modeling (e.g., FEA) or trial-based experiments to improve the process. It is desired to establish the relationship between the quality criteria and controllable process parameters or material properties to improve the coating performance. Due to the complexity of physics phenomena and sources of variation involved in the coating process, applying a universal model to understand the root cause of defect formation is difficult.

  Therefore, this project will propose a multi-stage modeling framework by decomposing the coating process into multiple smaller and simpler processes and applying different modeling approaches to qualify the outcome of each subprocess. Then, the optimal process parameters can be achieved by back-propagating the multi-stage model. This project will take one type of defect as an example to implement the proposed optimization framework based on multi-stage modeling.

• Interactions between Corrosion and Fatigue of Sintered Particle and Particle Free Based Ag and Cu Bond and Interconnects - Nikolay Dimitrov, Peter Borgesen

  Nano-porous structures tend to be much more sensitive to corrosion owing to the intrinsic interpenetrating solid-void structure with highly curved nano-sized ligament surfaces. Often, this sensitivity may be strongly enhanced by even very mild cyclic loading. However, much more critical for many applications is that long before corrosion becomes electrically measurable, it may strongly reduce the ductility and fatigue resistance of the structures.

  There is a growing interest in the use of sintered Ag, and recently Cu, as both self supporting joints and bonds as well as lines on various substrates. So far these are most often formed by sintering of (nano)particle filled pastes, but an alternative showing considerable promise for printing is the use of particle free inks (‘liquid metal’). In either case this may often lead to considerable surface roughness. The primary issue is, however, that regardless of the ink/precursor, all the structures will have some degree of (nano)porosity.

  First of all, the proximity of more of the conduction path to an open surface obviously makes for faster degradation by corrosion. In particular, progression in depth is enhanced because many of the relatively narrow links between nanoscale particles include a high angle grain boundary. In addition, mechanical deformation tends to be concentrated in the links so cyclic loading induced dislocation structures tend to further enhance rates of corrosion there. In many cases it may, however, be much more critical that initial conversion of the metals into oxides near the surface will tend to affect the deformation properties of the links. This happens long before effects on electrical conduction becomes significant and may severely degrade the fatigue resistance. On the other hand, an alternative corrosion mechanism that converts the structures into a soluble ionic form may not have quite as immediate an effect.

  It is proposed to characterize the strong interactions between corrosion and fatigue for representative nano-materials and nano-sized structures. The longer-term goal is a quantitative understanding of the mechanisms, establishment of materials selection and process guidelines, and the definition and development of test protocols and models for different applications. That would require funding beyond one year, perhaps from an outside agency like SRC. Also, it is anticipated that this line of studies could eventually be extended to other metals and funded by federal agencies.

  A first-year effort will characterize representative sintered Ag and Cu structures, establish test capabilities, design test vehicles, identify the main corrosion promoting process(es), and demonstrate typical magnitudes of interactions between corrosion and fatigue.

• Computational Engineering of Materials with High Thermal Conductivities for Electronics Packaging - Mengen Wang
  With the development of high-power and high-frequency electronics, electronic packaging materials are crucial to ensure the reliability and performance of the devices. The proposed work aims to use first-principles computational methods to enhance the thermal transport properties of boron-related materials and interfaces for electronic packaging applications. We will focus on hexagonal boron nitride (h-BN) and cubic boron arsenide (c-BAs) and investigate the impact of interfaces, strain, and defects on their thermal conductivities. By analyzing the electronic and phonon properties of these materials and interfaces, and conducting explicit calculations of their thermal conductivities, we aim to provide strategies for strain, interface and defect engineering that can further improve the performance of h-BN and c-BAs for electronic packaging. Our research will contribute to the development of high-thermal-conductivity materials that can meet the increasing demands in electronics packaging.

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