This paper introduces an ontology-based Digital Twin (DT) architecture for the lighting industry, integrating simulation models, data analytics, and visualization to represent luminaires. The ontology standardizes luminaire components, facilitating interoperability with design tools. The calculated ontology-level metrics suggest mid-level complexity with Size Of Vocabulary (SOV) at 37, Edge-to-Node Ratio (ENR) at 0.865, Tree Impurity (TIP) at 0, and Entropy Of Graph (EOG) at 2.61. A use case explores the utility of the ontology in the design phase across two different geographical locations, assessing environmental adaptability. The ontology captures opto-thermo-electric interactions, providing insights into luminaire performance. Results from inflating the DT and conducting simulations align with existing literature, indicating a degradation of around 12% over 8 years on the radiant flux. This ontology, up to the authors’ knowledge, is the first formal definition for the lighting industry, aiming to encompass the entire luminaire lifecycle. The current focus is on design and operational phases, with potential future enhancements to include real-time monitoring for performance evaluation and predictive maintenance. This work contributes to luminaire analysis and supports the development of sustainable lighting solutions in the industry.

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Model order reduction techniques are developed and utilized to make numerical simulations more efficient. The use of Reduce Order Models (ROM) also enables data exchange with external parties without disclosing the sensitive information present in a Full-Order Model (FOM). It is crucial to optimize for both the efficiency and accuracy of a ROM to keep a minimal deviation from the FOM. The complexity of a ROM-based simulation depends on the definition of the ROM as well as its connection with the remaining FOM. This paper investigates the effect of different ROM-FOM interface definitions for a test case consisting of an electronic package-on-PCB assembly. A virtual Design of Experiments (DoE) was carried out with a total of 41 cases considering three different locations and up to four different constraint equations for the ROM-FOM interface. The effect on the accuracy and time-efficiency of the ROM-based thermomechanical simulations are compared with respect to the full Finite Element (FE) model. The deformable configuration for the interface generally showed the most accurate results, while the rigid configuration was the most efficient across the board. The beam configuration did not always follow an expected trend based on the order of elasticity values of the assigned materials. Based on the deformation results and the time associated with ROM generation and use-pass, multiple optimal solutions from the DoE are discussed.@en

Solder joint failure is one of the most common board-level failure modes in electronic components. It is crucial for a next-generation reliability assessment method to have an in-situ health monitoring system in place to evaluate the current state of degradation. This is achieved by specialized embedded sensors and processing the data on the edge. This study focuses on monitoring the mechanical degradation of package-to-PCB solder interconnects of a WLCSP using a high-resolution piezoresistive sensor. First, a measurement workflow was set up to optimize and significantly improve the sensor readout time. Then, utilizing a design of experiments, the test specimens were subjected to certain combinations of mechanical and thermal loads in a four-point bending setup. Temperature-coupled mechanical loading showed a greater impact on the resulting stress pattern compared to that of a superposition of the corresponding individual purely thermal and mechanical load configurations. Finally, the specimens were tested under a purely mechanical load until failure, and a correlation between the recorded stress pattern and the initiation and propagation of a crack was established.@en

Semiconductor devices are commonly encapsulated with Epoxy-based Moulding Compounds (EMC) to form an electronic package. EMC typically occupies a large volume within a package, and thus, governs its thermomechanical behaviour. When exposed to high temperatures (150°C and above), electronic packages predominantly show oxidation of the outer layer of EMC. Oxidized EMC exhibits notably different material properties, resulting in a modified deformation pattern of a thermally aged package under varying thermal loads. As the oxidation layer grows in thickness, its mechanical properties also evolve, indicating distinct phases of the oxidized material at different stages of thermal ageing. Reflecting these changes (i.e., the current state of degradation) into a Finite Element (FE) model-based analysis can provide better insights into failure prediction and component reliability. It requires updating the geometry and material behaviour as a function of ageing. This paper presents a systematic procedure to build a continuously updated physics-based Digital Twin of a thermally aged flip-chip package that can represent intermediate oxidation stages. First, experimental measurements are carried out to quantify the growth of the oxidation thickness at 150°C and a diffusion-dominant mathematical model is proposed. Then, an accurate geometry of the test package is prepared with a parametric outer layer from all exposed sides of EMC to represent the oxidized layer at different stages of thermal ageing. Next, the experimental characterization of a few partially oxidized EMC specimens is done, and analytical methods are utilized to extract the thermomechanical properties of the oxidized EMC at different stages of ageing. Experimental warpage data of aged test packages are utilized to verify the defined material-model parameters that represent curing shrinkage, thermal expansion, glass transition, and corresponding elasticity moduli of the oxidized EMC at select stages of ageing. Then, a workflow to establish continuity in the material model is presented. Finally, the developed Digital Twin is utilized for an FE analysis to study the change in the trend of out-of-plane package deformations as a function of several stages of EMC oxidation.@en

Digital Twins (DT) play a key role in Industry 4.0 applications, and the technology is in the process of being mature. Since its conceptualisation, it has been heavily contextualised and often misinterpreted as being merely a virtual model. Thus, it is crucial to define it clearly and have a deeper understanding of its architecture, workflow, and implementation scales. This paper reviews the notion of a Digital Twin represented in the literature and analyses different kinds of descriptions, including several definitions and architectural models. A new fit-for-all definition is proposed which describes the underlying technology without being context-specific and also overcomes the pitfalls of the existing generalised definitions. In addition, the existing three-dimensional and five-dimensional models of the DT architecture and their characteristic features are analysed. A new simplified two-branched model of DT is introduced, which retains a clear separation between the real and virtual spaces and outlines the latter based on the two key modelling approaches. This model is then extended for condition monitoring of electronic components and systems, and a hybrid approach to Prognostics and Health Management (PHM) is further elaborated on. The proposed framework, enabled by the two-branched Digital Twin model, combines the physics-of-degradation and data-driven approaches and empowers the next generation of reliability assessment methods. Finally, the benefits, challenges, and outlook of the proposed approach are also discussed.@en

Moulding compounds used for encapsulating electronics typically occupy a large portion of package volume and are most exposed to the external environment. Under harsh conditions such as high temperature, humidity, and mechanical vibrations, constituent materials of electronic components degrade, resulting in a change in their thermal, mechanical, electrical, and chemical behaviour. High-temperature ageing of electronic packages causes the oxidation of epoxy moulding compounds (EMC), forming a layer exhibiting significantly different thermomechanical properties. This reflects in the modified mechanical behaviour of the entire package, which accelerates certain failure modes and affects component reliability. Thus, it is crucial to consider gradual degenerative changes in EMC for a more accurate estimation of the component lifetime. This paper proposes a three-step modelling approach to replicate thermo-chemical changes in package encapsulation. A parametric geometry of a test package was incorporated with the ageing stage-dependent changes in thermomechanical properties of the oxidized layer. The mechanical behaviour of oxidized EMC at multiple stages of thermal ageing (at 150°C for up to 3000 hours) was first experimentally characterized and then validated using warpage measurements on thermally aged test packages and Finite Element (FE) simulations. Lastly, a trend-based interpolation of material model parameters for intermediate stages of ageing was followed, and a continuously updated degradation model (physics-based Digital Twin) was achieved. The proposed model is capable of reproducing degraded stages of the test package under thermal ageing along with its modified thermomechanical behaviour. Its limitations and significance in the domain of health monitoring of microelectronics are also discussed.@en

Digital Twin can be broadly described as a continuously updated virtual representation of an object, system, or process which replicates all phases in the lifecycle of its physical counterpart. Originally conceptualized in 2003 [1], the term `Digital Twin' came into existence after it first appeared in NASA's roadmap in 2010 [2]. The concept initially evolved within the framework of aerospace and manufacturing applications and has picked up a lot of traction in the past five years. Digital Twin is now commonly used in the context of products, processes, businesses, etc., and it has been embraced by many other industries such as healthcare and electronics. The adoption of electronic devices and components in various applications has shown steep growth in last ten years, where some of the applications require them to withstand harsh environments. Thus, prognostics and health management (PHM) of microelectronics has gained importance more than ever. So far, the concept of Digital Twin has been implemented by contextualizing it for the respective use-case; and thus, it does not have a single fit-for-all definition or a standardized workflow. Therefore, it is crucial to clearly define a framework to implement a Digital Twin system for PHM of microelectronics. This presentation introduces such a framework adapted from a five-dimensional model [3] of Digital Twin. First, physics-based and data-driven approaches of modelling and lifetime-prognosis are described, and their limitations on an individual basis are discussed. Then, a hybrid approach, which utilizes both of the aforementioned approaches as building blocks, is introduced along with its additional requirements such as the `physics-of-degradation' models. Fundamental differences between a model and a Digital Twin of a product have been addressed, and three different complexity-levels (weak, cloud, and edge) of connections to the physical entity are discussed. The conflict of using edge and cloud-based computing for data-driven models, as well as the advantages of utilizing both of them together is also briefly touched upon. Lastly, an example of implementing the hybrid approach for monitoring temperature and humidity induced package-level degradation is presented. @en

Epoxy molding compound (EMC) is widely used for encapsulating automotive electronics. Among all of the components of an electronic package, EMC is most exposed to the atmosphere, and thus undergoes aging. During high-temperature operation, EMC is oxidized, which alters its mechanical properties, and thus can affect the reliability of electronic components. This chapter focuses on four key aspects of EMC oxidation – (1) the growth of EMC oxidation layer, (2) the mechanical properties of oxidized EMC, (3) the effect of oxidized EMC on thermomechanical behavior of a molded package, and (4) the effect of EMC oxidation on solder joint reliability. This study utilizes various experimental characterization techniques as well as finite element simulation-based analysis.@en

Epoxy-based molding compounds (EMC) are widely used to encapsulate automotive electronics. Under high temperature operation, EMC is oxidized and undergoes degradation in mechanical properties. This can alter the thermomechanical behavior of encapsulated electronic components, and thus can affect their reliability. Three key aspects of EMC oxidation in the context of microelectronics reliability are presented in this paper – (1) degradation of EMC specimens is studied under high temperature aging at three different temperatures – 170°C, 200°C, and 230°C for up to 1500 hours and the oxidation growth is documented as a function of aging duration and temperature using a fluorescence microscope; (2) critical thermomechanical properties of oxidized EMC (viz., elastic modulus, thermal expansion coefficient, and glass transition temperature) are experimentally characterized using fully-oxidized specimens; (3) the effect of EMC oxidation on thermomechanical behavior of an electronic package is investigated by comparing the deformation of a thermally aged package with that of a pristine package under a thermal cycle. This study indicates that EMC oxidizes rapidly during early stages (≈ 24 hours) of exposure to high temperature, and the oxidized layer exhibits significantly different thermomechanical properties. Thus, thermal aging develops a much stiffer package behavior, which is crucial for an accurate reliability assessment.

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