Packaging Configurations Research Articles

780 nm Narrow Linewidth External Cavity Diode Laser for Quantum Sensing

To meet the demands of laser communication, quantum precision measurement, cold atom technology, and other fields for narrow linewidth and low-noise light sources, an external cavity diode laser (ECDL) operating in the wavelength range around 780 nm was set up with a Fabry–Pérot etalon (F–P) and an interference filter (IF) in the experiment. The interference filter type ECDL (IF–ECDL) with butterfly-style packaging configuration has continuous wavelength tuning within a specified range through precise temperature and current control and has excellent single-mode characteristics. Experimental results indicate that the output power of the IF–ECDL is 14 mW, with a side-mode suppression ratio (SMSR) of 54 dB, a temperature-controlled mode-hop-free tuning range of 527 GHz (1.068 nm), and an output linewidth of 570 Hz. Compared to traditional lasers operating at 780 nm, the IF–ECDL exhibits narrower linewidth, lower noise, and higher spectral purity, and its dimensions are merely 25 × 15 × 8.5 mm3 weighing only 19.8 g, showcasing remarkable miniaturization and lightweight advantages over similar products in current research fields.

Impact of Different Packaging Configurations on A Topical Cream Product

PurposeThe objective of this study was to investigate whether different dispensing processes can alter the physicochemical and structural (Q3) attributes of a topical cream product, and potentially alter its performance.MethodsAcyclovir cream, 5% (Zovirax®) is sold in the UK and other countries in a tube and a pump packaging configurations. The structural attributes of the cream dispensed from each packaging configuration were analyzed by optical microscopy, confocal Raman microscopy and cryo-scanning electron microscopy. Rheological behavior of the products was also evaluated. Product performance (rate and extent of skin delivery) was assessed by in vitro permeation tests (IVPT) using heat-separated human epidermis mounted in static vertical (Franz-type) diffusion cells.ResultsDifferences in Q3 attributes and IVPT profiles were observed with creams dispensed from the two packaging configurations, even though the product inside each packaging appeared to be the same in Q3 attributes. Visible globules were recognized in the sample dispensed from the pump, identified as dimethicone globules by confocal Raman microscopy. Differences in rheological behaviour could be attributed to these globules as products not dispensed through the pump, demonstrated a similar rheological behaviour. Further, IVPT confirmed a reduced rate and extent to delivery across human epidermis from the product dispensed through a pump.ConclusionsDifferent methods of dispensing topical semisolid products can result in metamorphosis and Q3 changes that may have the potential to alter the bioavailability of an active ingredient. These findings have potential implications for product developers and regulators, related to the manufacturing and comparative testing of reference standard and prospective generic products dispensed from different packaging configurations.

Accelerated Predictive Stability Study of a Pediatric Drug Product for a Supplemental New Drug Application.

In this paper, we report two Accelerated Stability Assessment Program (ASAP) studies for a pediatric drug product. Whereas the first study using a generic design failed to establish a predictive model, the second one was successful after troubleshooting the first study and customizing the study conditions. This work highlighted important lessons learned from designing an ASAP study for formulations containing excipients that could undergo phase change at high humidity levels. The stability predictions by the second ASAP model were consistent with available long-term stability data of the drug product under various storage conditions in two different packaging configurations. The ASAP model was part of the justifications accepted by the health authority to submit a stability package with reduced long-term stability data from the primary stability batches for a Supplemental New Drug Application (sNDA).

Symmetric laminates for enhanced tire durability: A numerical study on belt edge separation

Tire failure due to belt edge separation is a common issue caused by various factors such as adhesion loss, high heat generation, and interlaminar shear. This research paper focuses on studying the phenomenon of belt edge separation in tires by investigating the effect of belt lay arrangement on this failure mode. The study examines two types of belt arrangements, namely Symmetric and Asymmetric, in both four belt and three belt package configurations, using advanced finite element analysis (FEA) techniques. MSC-MARC commercial Finite Element software is employed to conduct FE analysis on an 11R22.5 tire model under steady-state rolling conditions. Through numerical simulations, the study reveals that the symmetric belt arrangement, irrespective of the belt package configuration (four belt or three belt), minimizes strain energy density, principal strains, and principal stresses in the belt edge region compared to the asymmetric arrangement. Interestingly, the asymmetric arrangement is commonly used by tire companies for Truck Bus Radial (TBR) tires. Based on the findings of numerical simulations, this research paper proposes a new three belt package configuration that effectively utilizes the symmetric belt lay arrangement as a potential solution to reduce belt edge separation in TBR tires.

Reconfigurable Manufacturing Systems through Intelligent Workpiece Handling and Artificial Intelligence

In recent years, businesses have strived to align their manufacturing goods with the unique needs and preferences of their customers. However, the mass customization paradigm introduces challenges mostly associated to the manipulation of small product batches and knowledge management. This paper proposes a framework for intelligent reconfigurable manufacturing systems, that leverages robotic automation supported by a collaborative dual-arm manipulator, cognitive mechatronic devices, and machine-learning algorithms. In more detail, pioneer end-effectors and machinery provide the capacity of grasping and handling a variety of products without time-consuming hardware modifications. The backbone of this manipulation scheme is a set of machine learning tools for: a) the planning and synchronization of handling agents, b) identification and localization of workpieces, c) the generation of optimal packaging configurations based on customer orders and identified workpieces, and d) the allocation of the respective handling operations to robots, operators, and machinery. The proposed framework is evaluated through its implementation on a use case deriving from the metal industry. The particularities of this use case, as expressed in product variety, workpiece complexity, customer orders and intralogistics, provide a fertile ground for the validation of the discussed technologies.

Chiplets Integration: Simplifying the Landscape

Heterogenous integration and the use of chiplets are the logical outcome of several factors effecting the IC industry’s drive towards higher and higher performance, and to accomplish this at minimum total product cost. This drive to heterogenous solutions has created a new development cycle in the IC Packaging industry to get ready for these product needs. The choice of which package to use for chiplet-based designs is driven by several important factors, most importantly, the type of die-to-die interface that is being used. This bus largely defines the physical structure such as line and space requirements, and the electrical performance which influences the type of materials used as dielectrics and design practices which must be enabled to permit a successfully product design. There are a growing number of package configurations to accommodate these chiplet integrations, but in vast majority of real-world applications, there are only a handful of package types, with clear rationale guiding package selection. This paper will examine the different approaches for heterogeneous packaging and try to simplify the IC packaging selection process, and provide guidance for real-world implimenations. Although there are many different trade names in the industry there are only a few basic categories, and once this is understood the package selection should seem much less daunting.

MATHEMATICAL MODEL AND NUMERICAL SIMULATION OF OXYGEN TRANSPORT IN MULTILAYER FOOD PACKAGING: A SEMI-ANALYTICAL APPROACH

The purpose of this work was to develop a numerical simulation methodology using a free software capable of predicting the behavior of oxygen in multilayer polymeric systems to optimize packaging configurations with a greater barrier to O2. The Laplace Transform method was used to solve partial differential equations, with numerical inversion by the Stehfest algorithm together with the Gauss-Sidel method. It was possible to simulate the oxygen concentration profile in packaging systems containing two or three materials in the configuration. For some systems, the increase in the simulation time caused a numerical fluctuation at the material interface, especially if oxygen diffused from a material with greater diffusivity to one with lower diffusivity. The numerically simulated oxygen concentration profile can be associated with results from the literature, experimentally validated. The results showed to be promising for application in diffusion problems of multilayer systems, and the methodology can be used to describe systems with more layers. Mathematical modeling and numerical simulation have been allies to predict the behavior of oxygen in different materials and layer configurations, and it is relevant to provide a better understanding of the oxygen transport fundamentals involved and shorten product development cycle time and cost, contributing to the economy and new product development.

A Physics-of-Failure Investigation of Flip Chip Reliability Based on Lead-Free Solder Fatigue Modeling

Solder fatigue failure is one of the primary wear out failure mechanisms limiting reliability in microelectronics flip chip packaging. Solder fatigue failure occurs when a crack initiates and subsequently propagates through the entirety of the solder joint causing an electrical open. Crack initiation and propagation within a solder joint is caused by a cyclic application of stress, typically induced by exposure to temperature cycle excursions. Understanding the relationship between thermal cycling during product use and the accelerated thermal cycles used for testing is critical for predicting device reliability. MIL-PRF-38535 is the guiding aerospace and high reliability General Specification for Integrated Circuits (Microcircuits) Manufacturing that defines manufacturing, qualification and certification requirements for products to be listed on the Defense Logistic Agency’s (DLA) Qualified Manufacturer Listing (QML). Revision M of this standard, targeted for release in 2022, for the first time includes the use of lead-free solder alloys and organic substrates in the manufacturing of QML flip chip products. Hence there is a strong need to understand the physics-of-failure (PoF) concerning solder fatigue of lead-free flip chip assemblies. This paper demonstrates how finite element modeling can be used to predict solder fatigue for flip chip package assemblies. The authors have leveraged fatigue lives measured for different flip chip daisy chain package configurations, as well as fatigue lives defined and available in published papers. The authors then use the resulting lead-free solder fatigue model to perform parametric studies looking at the impact of different die sizes, underfill material properties, and package substrate materials. Comparisons are also made between eutectic Sn/Pb and lead-free fatigue life predictions. In addition, the authors demonstrate how solder fatigue predictions can be de-rated to use conditions in order to make reliability assessments for flip chip package assemblies. This ultimately leads to a better understanding of the impact of solder alloy and material selection on the mission life of aerospace and high reliability products that fall under the changes introduced in MIL-PRF-38535 Revision M.

Digital Twins and Smart Manufacturing for Wire Bonding

Low cost, excellent flexibility, and high yield rate have long been the drivers of wire bonding technology. In the past decade, advancements in wire bonding technology have significantly improved wire bond reliability and strengthened the adoption of the technology while maintaining its competitive advantage. Digital twins of wire bonding can now simulate and optimize 3D wire loop shapes to facilitate design-for-manufacturing (DFM), increase design flexibility, reduce product development time, and improve overall package yields. In particular, the benefits of digital twins have been realized in system-in-package (SiPs), large stack-die memory applications, and complex high pin count packages with multiple looping tiers. With increasing package complexity and modular package configurations, the need for smarter functionalities is imperative. More recently, technological developments in wire bonding have been targeted toward furthering design, quality, and time-to-market (TTM) from an Industry 4.0 smart manufacturing perspective. In this paper, we will introduce new digital twin simulation techniques to detect potential interference between wire bond capillaries and wire loops, various dies, passive components, and other structures within the package. These advanced capabilities are demonstrated on a real application and shown to help in the detection of design issues early in the product cycle and aid in the selection of capillary, wire, as well as optimization of the package layout. All these factors significantly improve the overall TTM of semiconductor packages. Technologies that provide improvements via autonomous monitoring and optimization are also strongly desired. We will also explore new on-bonder process monitoring capabilities to detect wire sway such that wire shorts and resultant yield losses can be minimized. Additionally, vision-guided enhancements to on-bonder loop height monitoring capabilities will also be discussed. These new advancements significantly improve production quality and yield, paving the way for smarter factories

Designing Antioxidant and Antimicrobial Polyethylene Films with Bioactive Compounds/Clay Nanohybrids for Potential Packaging Applications

In the present work, direct incorporation of bioactive compounds onto the surface and interlayer of nanoclays before their incorporation into the final polymeric film was conducted, based on a green methodology developed by our group that is compatible with food packaging. This will lead to the higher thermal stability and the significant reduction of the loss of activity of the active ingredients during packaging configuration. On this basis, the essential oil (EO) components carvacrol (C), thymol (T) as well as olive leaf extract (OLE), which is used for the first time, were incorporated onto organo-modified montmorillonite (O) or inorganic bentonite (B) through the evaporation/adsorption method. The prepared bioactive nanocarriers were further mixed with low-density polyethylene (LDPE), via melt compounding, in order to prepare films for potential use as fresh fruit and vegetable packaging material. Characterization of the bioactive nanocarriers and films were performed through XRD, TGA, tensile, antimicrobial and antioxidant tests. Films with organically modified montmorillonite loaded with carvacrol (OC), thymol (OT) and olive leaf extract (OOLE) at 5% wt. showed better results in terms of mechanical properties. The films with polyethylene and organically modified montmorillonite loaded with carvacrol or thymol at 20% wt. (PE_OC20 and PE_OT20), as well as with olive leaf extract at 5 or 10 %wt., clay:bioactive substance ratio 1:0.5 and 10% compatibilizer (PE_OOLE5_MA10 and PE_OOLE10_MA10) exhibited the highest antioxidant activity. The resulting films displayed outstanding antimicrobial properties against Gram-negative Escherichia coli (E. coli) with the best results appearing in the films with 10% OC and OT.

Aerosol Jet Printed Interconnects for Millimeter-Wave Components

As millimeter wave RF device applications expand above traditional microwave frequency bands in the global communications, automotive and Mil-Aero markets, the need to limit interconnect signal losses related to parasitic elements has never been more important. As the frequency increases, device designers are facing numerous challenges, complications, and costs when fabricating interconnects with techniques such as copper pillar bumps, wire, ribbon or wedge bonding in 3DIC packaging. Printing conformal interconnects with Aerosol Jet® direct-write technology can offer package designers and RF engineers a new approach for optimizing interconnect transitions to active die, tailoring the loss characteristics to specific application requirements and eliminating the need to compensate for high signal transmission losses. Printed interconnects can be digitally designed into the package with a variety of metallic and dielectric materials. As these interconnects are conformally printed on the 3D surface of the package, the trace length can be minimized with zero loop height, reducing parasitic inductance to active die circuitry specifically for die on board, die in trench, or die on die with pads-up packaging configurations. In this work, Aerosol Jet® printed interconnects with silver nanoparticle inks are compared with the gold microstrip transmission lines as well as traditional gold bond wires, for performance up to 110 GHz. We will share examples showcasing that the printed interconnects can have similar RF transmission performance to microstrip, with significantly lower loss than bondwires especially at high frequencies. We will also discuss design effects for Aerosol Jet® printed RF interconnects up to 110 GHz based on a set of results for different line heights with a given line width printed with a silver ink.

Characterization and Optimization of the Heat Dissipation Capability of a Chip-On-Board Package Using Finite Element Methods

The present study endeavors to investigate the thermal dissipation capability of a chip-on-board package by means of a comprehensive experimental and numerical analysis. For this purpose, a BiCMOS chip is designed and fabricated in conjunction with three different printed circuit board configurations, including a single-sided board, a thermal via board, and a copper frame board. Transient thermal measurements are carried out on all three packages, and the results are subsequently transformed into cumulative structure functions. Then the finite element models are established for each package configuration, and their validity is confirmed through comparison with the experimental structure functions. The models are then characterized in accordance with the JEDEC 38-set boundary conditions, followed by a series of optimizations targeted towards the printed circuit board, including the board stack-up and the board sizes. Parametric studies are performed to quantitatively assess the impact of these parameters on the thermal performance. Finally, the present study provides a comprehensive discussion of the optimal application scenarios for each board configuration, with a view to achieving good thermal performance. The findings of this study will contribute to the development of more thermally effective chip-on-board packages for high-performance electronic systems.

Digital twins for selecting the optimal ventilated strawberry packaging based on the unique hygrothermal conditions of a shipment from farm to retailer

Berries are one of the most challenging products to preserve after harvest due to their high perishability and short shelf life. Ventilated packaging plays a key role in maintaining fruit quality along the supply chain. However, every supply chain is composed of different unit operations, and every shipment encounters unique hygrothermal conditions such as air temperature fluctuations over time, sub-optimal humidity conditions, and the risk of condensation. Therefore, every supply chain has an optimal packaging that provides the best hygrothermal climate and ventilation to the fruit. Given the vast space of potential supply chain scenarios and packaging configurations, in-silico studies are an attractive alternative for selecting this optimal packaging. In this study, we developed physics-based digital twins for ventilated packaging of strawberries. We utilized measured air temperature and humidity data from an actual supply chain from the farm to the retail store. With these digital twins, we mimicked in-silico how the strawberries evolve hygrothermally, physiologically, and microbiologically along the supply chain inside 21 different types of ventilated packaging. We predicted actionable metrics of fruit quality and shelf life for these 21 packages. These metrics include total mass loss, risk of putative mold infection due to Botrytis cinerea, retention time of condensate, and remaining shelf life based on respiration, transpiration, and mold growth. In addition, we analyzed the impact of package-related metrics, such as total vent area, degree of filling, pressure drop across the package, and seven-eighths cooling time, on fruit quality metrics. With this approach, we pinpointed the critical quality loss points in the supply chain for every package. We identified the package that performs best in balancing the three-way trade-off between the respiration-driven biochemical shelf life, transpiration-driven physical shelf life, and mold growth-driven microbial shelf life of fruit. Our findings showed that the performance of open trays is comparable to ventilated clamshells, as long as a high humidity is maintained along the supply chain. Flow-wrapped packages presented the highest risk of condensation and microbial growth. We also quantified the spatial heterogeneity in fruit quality within the packages and highlighted the most vulnerable locations for quality loss inside each packaging type. Our study presents a novel, holistic approach to select the optimal ventilated packaging of strawberries from farm to retailer based on its measured hygrothermal fingerprint. This approach can help reduce food loss and contribute towards making supply chains smart and efficient.

Evaluating Aseptic Presentation of Different Medical Device Packaging Configurations.

The Medical Device Regulation (MDR) of the European Union (EU) places greater emphasis on the usability of medical devices, with the goal of eliminating or reducing the risk of infection to patients. As this goal also is applicable to sterile packaging, ANSI/AAMI/ISO 11607-1:2019 introduced a usability evaluation requirement for aseptic presentation of terminally sterilized medical devices. In an effort to reduce contamination risks, this requirement focuses specifically on the sterile barrier system (SBS). However, research is limited on evaluating the usability of SBSs and their performance, from an aseptic presentation standpoint, in clinical settings. To address this research gap, we assessed 14 sterile medical devices with five different SBS configurations to elucidate how SBS configuration (type, size, and number of SBS layers) and user satisfaction levels affect usability. A total of 40 experienced clinical nurses participated in 280 individual trials (20 per SBS configuration), which were conducted in a simulated operating room. Ultraviolet fluorescent powder was used to simulate the contamination process and to evaluate the success or failure of the aseptic presentation. Pouch and tray configurations exhibited the best overall performance, while vent bags performed poorly and were considered less acceptable. Double SBS configurations outperformed single SBS configurations. The study highlighted the importance of appropriate SBS symbols to identify SBS layers, which is another patient safety-related requirement of the EU MDR. The current work also includes an analysis of the powder contamination method used in conducting the usability evaluation.

Comparison of different RGB InP-quantum-dot-on-chip LED configurations.

InP/ZnSe/ZnS quantum dots (QDs) offer a cadmium-free solution to make white LEDs with a narrow blue, green and red emission peak. Such LEDs are required for display and lighting applications with high color gamut. An important phenomenon that hampers the efficiency of such quantum-dot-on-chip LEDs is re-absorption of already converted light by the QDs. Proposed solutions to remedy this effect often rely on complex or cost-ineffective manufacturing methods. In this work, four different RGB QD-on-chip LED package configurations are investigated that can be fabricated with a simple cavity encapsulation method. Using accurate optical simulations, the impact of QD re-absorption on the overall luminous efficacy of the light source is analyzed for these four configurations as a function of the photo-luminescent quantum yield (PLQY) of the QDs. The simulation results are validated by implementing these configurations in QD-on-chip LEDs using a single set of red and green emitting InP/ZnSe/ZnS QDs. In this way, the benefits are demonstrated of adding volume scattering particles or a hemispherical extraction dome to the LED package. The best configuration in terms of luminous efficacy, however, is one where the red QDs are deposited in the recycling cavity, while the green QDs are incorporated in the extraction dome. Using this configuration with green and red InP/ZnSe/ZnS QDs with a PLQY of 75% and 65% respectively, luminous efficacy of 102 lm/W was realized for white light with a CCT of 3000 K.

A Polyanionic Strategy to Modify the Perovskite Grain Boundary for a Larger Switching Ratio in Flexible Woven Resistive Random-Access Memories.

The intergranular interface modification of organic-inorganic hybrid perovskites (OHP) is an important issue to regulate the flexibility, stability, and resistive switching (RS) performance of resistive random-access memories (RRAMs). A novel strategy of polymer additives for OHP intergranular interface modification is explored in this work with the polyanionic backbone to improve the distribution of cage-shaped cavity molecules at the perovskite grain boundaries. Specifically speaking, poly(1-adamantylammonium acrylate) (PADAm) is first synthesized through the acid-base reaction of polyacrylic acid with 1-adamantylamine to simultaneously realize the introduction of a cage-shaped cavity molecule and the polyanionic backbone. Herein, organic ammonium cations 1-adamantylammonium (ADNH3+) in PADAm are applied as the cage-shaped cavity molecules to tune the dielectric property by being anchored at the perovskite grain boundaries. Meanwhile, polyacrylic anions in PADAm play the role of the polyanionic backbone to produce the more uniform distribution of ADNH3+. Simultaneously, the flexibility and stability of OHP RRAM devices are also improved due to the introduction of the polyanionic backbone. Consequently, the 4% ADNH3I-modified planar device exhibits the stable nonvolatile RS behavior with an on/off ratio of ∼104, even with one-month exposure under an ambient environment. Importantly, the introduction of PADAm in the flexible fibrous crosspoint of functional fiber Al@MAPbI3:PADAm and bare Al fiber further increases the on/off ratio to 108 due to the effectively improved distribution of hollow cage-shaped ADNH3+ at the perovskite intergranular interfaces together with the application of the fibrous crosspoint device configuration. Especially, these excellent crosspoint RRAM devices can be integrated into the woven fibrous RRAM array in the thermal plastic packaging configuration. In addition, the excellent multilevel RS behavior can also be realized in the woven fibrous RRAM array, indicating potential high-density data storage. This work provides a novel strategy of polymer additives bearing the polyanionic backbone to improve the flexibility, stability, and RS performance of perovskite RRAM devices.

Effects of the equilibrium atmosphere on Taleggio cheese storage in micro perforated packaging

Taleggio is an Italian smear-ripened cheese, whose complex microbiota demands the optimisation of the packaging system to avoid excessive changes during storage. Metabolic processes of the cheese rind microbiota can be usefully exploited in equilibrium modified atmosphere packaging (EMAP) by balancing microbiota respiration and film permeation. Here, we present the application of three different micro perforated EMAPs as models for smear-ripened cheese compared to two control packaging configurations. Analyses of the main microbial groups, headspace gas, textural profile, and sensory properties were performed to find the best packaging for storage. Results showed that two of the alternative micro perforated packaging systems were able to control the excessive changes during storage, thus limiting fungal overgrowth and allowing the typical development of smear microbiota with minor changes to hardness and cohesiveness. Finally, the sensory evaluation positively favoured one of the alternatively packed cheeses based on its compactness, typical dairy traits, and minor off-flavours. These findings showed that EMAP can be a valid alternative solution to control the storage of Taleggio cheese. Further studies could be conducted to evaluate this system on other smear cheeses.

Sensitivity study of coupled chemical-CFD simulations for analyzing aluminum-clad spent nuclear fuel storage in sealed canisters

The United States Department of Energy (DOE) manages over 50 Metric Tons Heavy Metal (MTHM) of aluminum-clad spent nuclear fuel. One main source for DOE’s Aluminum-clad spent nuclear fuel (ASNF) inventory is the advanced test reactor (ATR) at the INL site, which makes this fuel of particular interest for storage scenarios. Road-ready and final disposition packaging configurations for the ATR fuel dictates storage within helium-backfilled, sealed DOE standard canisters. The conditions within these sealed canisters for extended (greater than50 year dry) storage is of interest. To further this goal, a three-dimensional (3D) multi-physics computational fluid dynamics (CFD) model is developed of the sealed DOE standard canisters. This 3D CFD model is one-way coupled with bulk gas radiolysis reactions considering sealed canisters with inert gas and possible trace amounts of air and water vapor. This study looks at the evolution of the thermal history of the canisters over a 50 year time period with a coupling to the chemical reactions occurring from radiolytic breakdown of residual water. A sensitivity study is then carried out over the parameters of the model including the fuel decay heat, residual water content, sealed pressure, canister external temperature, and canister emissivity. In pure helium, hydrogen generation rates are low, under 10 ppm, but hydrogen generation rates are affected greatly by the presence of even 1% residual air, increasing by 50-plus-fold, and nitric acid generation with residual air also occurs ranging from 500 to 4000 ppm after 50 years. The fuel decay heat and the residual water content show the most importance in the generation of hydrogen gas in pure air, and for nitric acid with a residual air condition. External temperature, canister emissivity and sealed pressure all show minor sensitivity effects to the generation of potentially harmful species.

Effects of modified atmospheric packaging configuration on spoilage mould growth in damaged packages of fresh pasta

Damaged packages of modified atmosphere packaging (MAP) containing food affect the growth of spoilage mould, leading to rejection of the product by the consumer before the use-by date. The effects of MAP configuration (CO2 concentration, initial gas volume) and storage temperature on the “rejection time” were investigated for fresh pasta, using packaging perforated with different micro-hole dimensions. The temperature was a significant factor that determined the rejection time; however, an interaction effect between MAP configuration and micro-hole in the damaged packages was also observed. This work showed that the micro-hole dimension in damaged packages determined the gas exchange ratio through the perforations and its competition with CO2 dissolution in the product. The CO2 transmission rate was found to increase with an increasing diameter of micro-hole in the packaging (r = 0.99; p < 0.05). These results suggested that CO2 dissolution was likely to occur in damaged packages containing micro-hole of <0.3 mm. Here, the appropriate MAP configuration could extend the rejection time of damaged packages to inhibit spoilage mould growth, and the best results were achieved using >50 % CO2 concentration in the gases used.

Low Thermal Conductivity Adhesive as a Key Enabler for Compact, Low-Cost Packaging for Metal-Oxide Gas Sensors

Metal-oxide (MOX) gas sensors commonly rely on custom packaging solution. With an ever-increasing demand for MOX gas sensors, there is a clear need for a low cost, compact and high-performance package. During normal operation, MOX sensors are heated up to a temperature in the typical range of 200-300°C. However, the generated heat must not damage or degrade any other part of the assembly. Using 3D finite elements modelling, we developed an optimal package configuration. To thermally insulate the assembly from the heated MOX sensor we have developed in-house a low thermal conductivity xerogel-epoxy composite with 22.7% by weight xerogel and a thermal conductivity of 107.9 mW m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> which is a reduction exceeding 30% compared to commercially available epoxy. Based on the low thermal conductivity xerogel-epoxy composite, we have developed a novel packaging approach that can suit the large family of MOX sensors. The developed alternative packaging solution includes a small number of assembly steps and uses standard processes and techniques. The assembled MOX sensor is low cost and has a low power consumption, while all thermally sensitive assembly parts remain at low temperature during the system’s lifetime.