Multilayer Packaging Structures Research Articles

PLA- and PHA-Biopolyester-Based Electrospun Materials: Development, Legislation, and Food Packaging Applications.

The high accumulation of plastic waste in the environment has led to great interest in biodegradable polymers, such as polylactic acid (PLA) or polyhydroxyalkanoates (PHAs). Their benefits, combined with the application of electrospinning technology, represent an innovative proposal for the food packaging industry. This article provides a comprehensive review of the latest developments of PLA- and PHA-biopolyester-based electrospun materials for food packaging applications, summarizing the reported technologies, material properties, applications, and invention patents. In addition, the legislation used to assess their biodegradability is also detailed. Electrospun packaging materials are largely developed through uniaxial, coaxial, emulsion, multiaxial, and needleless techniques. PLA- and PHA-biopolyester-based electrospun materials can be obtained as single and multilayer packaging structures, and the incorporation of natural extracts, organic compounds, and nanoparticles has become a great strategy for designing active food packaging systems. The biodegradability of electrospun materials has mainly been evaluated in soil, compost, and aquatic systems through ASTM and ISO normatives. In this review, the dependence of the biodegradation process on the polymer type, conditions, and test methods is clearly reviewed. Moreover, these biodegradable electrospun materials have shown excellent antioxidant and antimicrobial properties, resulting in a great method for extending the shelf life of fruits, bread, fish, and meat products.

Enhanced High-Rate Capability and Long Cycle Stability of FeS@NCG Nanofibers for Sodium-Ion Battery Anodes.

The development of advanced hierarchical anode materials has recently become essential to achieving high-performance sodium-ion batteries. Herein, we developed a facile and cost-effective scheme for synthesizing graphene-wrapped, nitrogen-rich carbon-coated iron sulfide nanofibers (FeS@NCG) as an anode for SIBs. The designed FeS@NCG can provide a significant reversible capacity of 748.5 mAh g-1 at 0.3 A g-1 for 50 cycles and approximately 3.9-fold higher electrochemical performance than its oxide analog (Fe2O3@NCG, 192.7 mAh g-1 at 0.3 A g-1 for 50 cycles). The sulfur- and nitrogen-rich multilayer package structure facilitates efficient suppression of the porous FeS volume expansion during the sodiation process, enabling a long cycle life. The intimate contact between graphene and porous carbon-coated FeS nanofibers offers strong structural barriers associated with charge-transfer pathways during sodium insertion/extraction. It also reduces the dissolution of polysulfides, enabling efficient sodium storage with superior stable kinetics. Furthermore, outstanding capacity retention of 535 mAh g-1 at 5 A g-1 is achieved over 1010 cycles. The FeS@NCG also exhibited a specific capacity of 640 mAh g-1 with a Coulombic efficiency of above 99.8% at 5 A g-1 at 80 °C, indicating its development prospects in high-performance SIB applications.

Sintering behavior and dielectric properties of ultra-low temperature glass/ceramic composites

Na2O-K2O-SiO2-B2O3-Al2O3-P2O5 (NKAP) glasses with low melting temperatures were obtained by melting. NKAP glass/ceramic composite ULTCC (ultralow temperature co-fired ceramic) materials were prepared at sintering temperature (<700 °C) by mixing traditional ceramic materials (alumina, quartz and zirconia) and low melting NKAP glasses. Quartz and monolithic zirconia can form stable composites with low melting NKAP glasses. Thus, we prepared ULTCC composite materials containing high amounts of quartz and zirconia. However, alumina and NKAP glasses partially reacted during sintering. Sintering temperature of NKAP glass/ceramic ULTCC composite was lower than 680 °C with the minimum sintering temperature of ˜ 550 °C. All samples containing NKAP glass/quartz ULTCC composites demonstrated excellent dielectric permittivity (equal to 6.51 with loss ˜8 × 10−3) and mechanical bending strength equal to 82 MPa. Our results can be used for fabrication of multilayer ULTCC packaging structures with tailored physical properties.

Thermal Stress Analysis of Chip Scale Packaging by Using Novel Multiscale Interface Element Method

In this study, a multiscale interface element method (MIEM) is developed to evaluate the interfacial peel and shear stress distributions in multilayer packaging structures. A newly developed polygon interface element contained many sides that could easily connect with many other polygon elements of much smaller scale. Simple model and less computation can obtain accurate stress distributions. After verification of the validity of the developed model, MIEM is applied to analyze thermal stress distribution of the chip scale package (CSP). In general, a good qualitative agreement has been observed between the various results. Moreover, MIEM can directly obtain the stress value at the interface, which is also one of the advantages of this method in dealing with multilayer structures.

Ground Bounce Noise Induced by Crosstalk Noise for Two Parallel Ground Planes With a Narrow Open-Stub Line and Adjacent Signal Traces in Multilayer Package Structure

This paper investigates how ground bounce noise (GBN) is generated by crosstalk noises for two parallel ground planes with a narrow open-stub line (NOSL) and adjacent signal traces in a multilayer package structure. A noise reduction scheme and design guidelines for preventing intense noises (GBN and coupled noise) are also proposed. A graphical method that is based on wave tracing is also developed to elucidate the generation of crosstalk noise by adjacent signal traces on an NOSL. The mechanism of generation of the GBN by crosstalk noise can be elucidated based on reflection theory, open-stub quarter-wavelength resonance, and parallel-plane resonance. The time-domain simulation results are analyzed using a 3-D full-wave simulator, Computer Simulation Technology. Using an additional shorting via at the connection between the NOSL and parallel ground planes, the proposed noise reduction scheme can significantly reduce the GBN and coupled noise. Moreover, guidelines for designing the test structure to minimize noise (GBN and coupled noise) are presented. Finally, the simulation and measurement results in the time domain are compared to validate the proposed analysis and noise reduction scheme.

Zein‐based ultrathin fibers containing ceramic nanofillers obtained by electrospinning. II. Mechanical properties, gas barrier, and sustained release capacity of biocide thymol in multilayer polylactide films

ABSTRACTThe combination of electrospinning technology and nanomaterials such as nanoclays can synergistically lead to novel materials with enhanced properties and functionalities for their usage in passive and active packaging applications. Part I of this work was focused on the development of ultrathin zein fibers containing nanoclays, which were oriented along the fiber axis and increased the thermal properties. Part II presents the use of the hybrid fibers as passive and active components in multilayer packaging structures. The hybrid fibers are incorporated in poly(lactic acid) films via a two‐step process: Electrospinning and compression molding. The composites thus produced presented improved mechanical and barrier properties than the unfilled material. The natural biocide extract thymol is then incorporated in the coating, and its sustained release properties are shown. The antimicrobial capacity of the hybrid fibers was also determined against foodborne bacteria. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40768.

Antenna-in-package (AiP) in mm-wave band

We studied the viability of the embedded wafer level ball grid array (eWLB) package environment as an antenna platform for 77 GHz automotive radar sensors and the effects of package fabrication tolerances on the antenna performance. The investigation of different antenna concepts in the eWLB package and their characterization methods are addressed. The design procedures for electrically large, differentially fed loop antennas in a multilayer package structure are introduced. Two different planar antennas are developed and measured in an eWLB package showing promising results such as a gain of 9 GHz and an impedance bandwidth of 8 GHz. An acceptable antenna performance is recorded within the tolerance limits. Therefore, the eWLB package is seen as an appropriate platform for mm-wave antennas and as a good candidate for an antenna-in-package (AiP) concept.

Packages With Integrated 60-GHz Aperture-Coupled Patch Antennas

This paper presents balanced-fed and fork-fed aperture-coupled patch antennas and 16-element arrays suitable for broadband millimeter-wave communications. The antennas are realized in a multi-layer organic package structure, to which RF integrated circuits can be integrated. To improve antenna bandwidth and radiation efficiency, an air cavity is used, resulting in a superstrate planar patch-antenna structure. Additionally, resonating apertures are used to further increase the antenna bandwidth. Measured results at 60 GHz for the antennas show good performance in terms of peak gain (about 8 dBi for a single element and 17 dBi for a 16-element array), bandwidth ( >; 10 GHz for 10-dB return loss bandwidths are achievable), and radiation efficiency (80% for single-element from simulation).

Uniaxial tensile behavior and thermoforming characteristics of high barrier EVOH‐based blends of interest in food packaging

AbstractThe uniaxial tensile characteristics of blends of an ethylene‐vinyl alcohol copolymer (EVOH‐32 mol% ethylene) with an amorphous PA and/or a nylon‐containing ionomer, used as barrier layer in multilayer food packaging structures, was assessed in this paper. The stress‐strain behavior of these materials at elevated temperatures and at different strain rates was examined. The stress‐strain curves obtained were used to understand the influence of temperature and strain rate on the uniaxial deformation process of the materials, these being of general importance during typical processing steps including thermoforming. A male mold for deep‐draw was used to assess the thermoforming (biaxial deformation in nature) behavior of extruded sheets at 100, 120, 140 and 150°C, and the results were broadly found to be in agreement with results from simple uniaxial tensile tests. From the preliminary thermoforming results, it was found that EVOH/aPA extruded blends did not improve the poor formability of EVOH alone. In contrast, significant improvement in thermoformability was achieved by blending EVOH with a compatibilized ionomer. Optimum forming capacity was achieved in a ternary blend by addition of a compatibilized ionomer to an EVOH/aPA blend in the range of 140°C–150°C. The ternary blend showed a lower reduction of thickness in the sidewalls, as well as a higher dimensional uniformity in the thermoformed part. Polym. Eng. Sci. 44:598–608, 2004. © 2004 Society of Plastics Engineers.

Study of the thermoformability of ethylene‐vinyl alcohol copolymer based barrier blends of interest in food packaging applications

AbstractThe thermoforming capacity of a number of blends of an ethylene‐vinyl alcohol copolymer (EVOH‐32, with 32 mol % ethylene) with amorphous polyamide (aPA) and/or Nylon‐containing ionomer with interest in multilayer food packaging structures have been studied. These blends were vacuum‐thermoformed between 100 and 150°C onto male molds of different shapes and areal draw ratios. It was found that EVOH/aPA extruded blends did not improve the inherently poor formability of EVOH alone. In contrast, significant improvements in thermoformability were achieved by blending EVOH with a compatibilized‐ionomer. Optimum forming capacity was achieved in a ternary blend by addition of a compatibilized‐ionomer to EVOH/aPA blends in the range of 140–150°C. Analysis of wall thickness data obtained in the thermoformed parts showed that wall thickness was significantly affected by the ionomer and amorphous polyamide content in the blend. The ternary blend showed a lower thickness reduction in the critical areas, as well as a higher uniformity in the part. A finite element analysis was used to evaluate the wall thickness distribution and the modeling results were compared with the thermoforming experiments. The simulations were performed for the vacuum‐forming process employing a nonlinear elastic material model. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 96: 3851–3855, 2004

IGBT Package Design for High Power Aircraft Electronic Systems

This paper will discuss the design of semiconductor packages having integrated air cooled heatsinks for use in high power electronic systems. It will demonstrate how simple models of the heat transfer from the heatsink fins, which are based on empirical correlations, may be utilized in combination with either simple analytical models or two-dimensional finite difference (FD) models of the heat conduction from the semiconductor die through the multilayer package structure to the base of the fins. These models allow the rapid evaluation of performance under both steady-state and transient overload conditions, and can be used to rapidly explore a wide range of design options before selecting candidate layouts for more detailed evaluation using 3D analysis tools. Wind tunnel experiments, which will also be reported, have been carried out to verify the modeling results for different semiconductor device layouts. These trials demonstrate excellent agreement between the models and experimental results.

THERMAL DESIGN OF HIGH POWER SEMICONDUCTOR PACKAGES FOR AIRCRAFT SYSTEMS

Future aircraft containing a greater proportion of electrical systems will require more extensive use of power electronics, for which thermal management is a key issue. This paper will present an approach to semiconductor package design incorporating integrated air cooled heatsinks. The paper will show how simple models of the heat transfer from heatsink fins, which are based on well established empirical correlations, may be utilised in combination with simple models of the heat conduction from the semiconductor die through the multilayer package structure to the base of the fins. These models allow the generation of design curves which may be used to rapidly explore a wide range of design options before selecting potential designs for more detailed evaluation using 3-D FE analysis. This approach has been used to design a semiconductor package for a power converter where the semiconductor devices are switched at high frequency to ensure good input and output current waveforms. The power dissipated in the semiconductors, and therefore the heatsink weight however increases with the switching frequency, whereas the associated filtering components will be smaller and lighter at higher frequencies. The optimisation of the overall system weight therefore involves a trade-off between the heatsinking and filtering requirements rather than just determining the optimum heatsink design for a specific power dissipation.

Resistance computations for multilayer packaging structures by applying the boundary element method : Ruey-Beei Wu. IEEE Trans. Compon. Hybrids mfg Technol.15, 87 (1992)

Resistance computations for multilayer packaging structures by applying the boundary element method : Ruey-Beei Wu. IEEE Trans. Compon. Hybrids mfg Technol.15, 87 (1992)

Resistance computations for multilayer packaging structures by applying the boundary element method

A boundary element formulation together with the moment method analysis is proposed to find the equivalent multiport DC resistances for packaging structures consisting of uniform conducting plates with arbitrarily shaped boundaries. Incorporated with a new equiangle division scheme and exact integration formulas, this approach is very efficient in the use of computer storage and computation time, allowing many practical structures to be dealt with even by a small personal computer. The method is employed to investigate the effect on the equivalent resistances due to the presence of the interior apertures and the exterior boundary. Also presented are the resistance modeling technique for the multilayer packaging structures and a novel cut and fill technique to estimate the resistances of complicated structures.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Gas transport in multilayer packaging structures

AbstractCalculation of gas permeation in food packaging structures can be done using a steady‐state analysis employing the permeability coefficient. While this approach is adequate for some applications, for many others a time‐dependent transport analysis must be considered to make quantitative predictions of shelf life. The limitation of the simple permeability analysis for multilayer structures is illustrated for Saran‐coated polycarbonate and poly(ethylene terephthalate) soda cans. These more detailed calculations on package structures can be done using standard computer library routines to include both the effect of gas sorption and diffusion.

Resistive modeling of periodically perforated mesh planes in multilayer packaging structures

The DC resistance of a periodically perforated mesh plane in a multilayer packaging structure is modeled by a network consisting of the equivalent resistances between any two holes. Through the use of the spectral analysis together with conformal mapping, analytic formulas for the equivalent resistances are derived for the mesh planes with holes of common shapes. For mesh planes with medium-size holes, the one-shell network constructed of the equivalent resistances between the nearest-neighbor and cross-corner holes is sufficient. However, if the hole size is small, the two-shell network which contains resistances to next-nearest holes should be used.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Electrical Modeling of Interconnections in Multilayer Packaging Structures

An effort toward modeling the interconnections in selected typical multilayer packaging structures is presented. The modeling is based on a quasi-static approximation to the associated electro-magnetic problems. A program for computing capacitance and inductance matrices and the numerical techniques used to improve the program efficiency are described. The results of numerical testing of the program are provided and discussed. The program was also compared with experimental data published in the open literature and the results are shown. The agreement between the model and the experiments is satisfactory.