Packaging Of Electronic Components Research Articles

Influence of Normal-to-High Anodizing Voltage on AAO Surface Hardness from 1050 Aluminum Alloy in Oxalic Acid.

Anodic aluminum oxide (AAO) has been widely applied for the surface protection of electronic component packaging through a pore-sealing process, with the enhanced hardness value reaching around 400 Vickers hardness (HV). However, the traditional AAO fabrication at 0~10 °C for surface protection takes at least 3-6 h for the reaction or other complicated methods used for the pore-sealing process, including boiling-water sealing, oil sealing, or salt-compound sealing. With the increasing development of nanostructured AAO, there is a growing interest in improving hardness without pore sealing, in order to leverage the characteristics of porous AAO and surface protection properties simultaneously. Here, we investigate the effect of voltage on hardness under the same AAO thickness conditions in oxalic acid at room temperature from a normal level of 40 V to a high level of 100 V and found a positive correlation between surface hardness and voltage. The surface hardness values of AAO formed at 100 V reach about 423 HV without pore sealing in 30 min. By employing a hybrid pulse anodization (HPA) method, we are able to prevent the high-voltage burning effect and complete the anodization process at room temperature. The mechanism behind this can be explained by the porosity and photoluminescence (PL) intensity of AAO. For the same thickness of AAO from 40~100 V, increasing the anodizing voltage decreases both the porosity and PL intensity, indicating a reduction in pores, as well as anion and oxygen vacancy defects, due to rapid AAO growth. This reduction in defects in the AAO film leads to an increase in hardness, allowing us to significantly enhance AAO hardness without a pore-sealing process. This offers an effective hardness enhancement in AAO under economically feasible conditions for the application of hard coatings and protective films.

Low dielectric constant and highly intrinsic thermal conductivity fluorine‐containing epoxy resins with ordered liquid crystal structures

AbstractEpoxy resins with a high dielectric constant and low intrinsic thermal conductivity coefficient cannot meet the current application requirements of advanced electronic and electrical equipment. Therefore, novel fluorine‐containing liquid crystal epoxy compounds (TFSAEy) with fluorinated groups, biphenyl units, and flexible alkyl chains are first synthesized via amidation and esterification reactions. Then, 4,4′‐diaminodiphenylmethane (DDM) is used as a curing agent to prepare the corresponding fluorine‐containing liquid crystal epoxy resins. The obtained dielectric constant (ε) and dielectric loss (tan δ) values of TFSAEy/DDM at 1 MHz are 2.54 and 0.025, respectively, which are significantly lower than those of conventional epoxy resins (E‐51/DDM, 3.52 and 0.038). Additionally, the intrinsic thermal conductivity coefficient (λ) of TFSAEy/DDM is 0.36 W/(m·K), 71.4% higher than that of E‐51/DDM (0.21 W/(m·K)). Meanwhile, the corresponding elastic modulus, hardness, glass transition temperature, and heat resistance index of TFSAEy/DDM are 5.73 GPa, 0.35 GPa, 213.5°C, and 188.7°C, respectively, all superior to those of E‐51/DDM (3.68 GPa, 0.27 GPa, 107.2°C, and 174.8°C), presenting potential application in high‐heating electronic component packaging and printed circuit boards.

Designs of ultra-HPHT Electrical Component Packages for Downhole and Geothermal Wellbore Logging Tool Integrations

Conventional dielectric sealing materials (PEEK, glass and glass-ceramic) used for sealing electrical feedthroughs, connectors, interconnectors and bulkheads in electronic packages can provide reliable downhole wellbore long-term logging tool service up to 150C or short-term logging service for greater than/equal 200C, due primarily to low glass transition temperature of the used sealing materials. This paper will demonstrate that the maximum allowable operating pressure and temperature could be from 20KSI to 100KSI and from 200C to 400C with Borosilicate and Bismuth-Boron-Silica (XTS) sealing glasses. Borosilicate glass sealed Inconel-Kovar/Kovar electronic housing could maintain reliability up to the maximum pressures of ~35KSI at 200C or 25KSI at 400C. Similarly, a Bismuth-Boron-Silica XTS glass sealed stainless steel electronic package housing could have a maximum operating pressure of ~100KSI at 150C or ~50KSI at 300C temperature. It has been found that high glass transition temperatures of (440-560)C for Borosilicate glass and (44010)C for Bismuth-Boron-Silicate (XTS) glass are key for making highly reliable ultra-HPHT electronic component packages. It is shown that the tetrahedral diamond-like microstructures of these sealing glasses are keys to ensure water-repelling properties to maintain sufficient electrical insulation resistance regardless of their use in water or moisture-rich wellbores. Moreover, compressive pin stress is found to be additional key for mitigate frequently observed glass seal cracks during logging tool field services.

Power Law Creep Behavior Model of Third Generation Lead-Free Alloys Considering Isothermal Aging

Abstract In realistic applications, the solder joint is continually subjected to thermal-mechanical stress due to the difference in the coefficient of thermal expansion between the printed circuit board substrate and the electronic packaging components. Creep and fatigue processes were the most common causes of failure in electronic assemblies. Under isothermal aging, creep deformation becomes more prominent. The aged microstructure was recognized by intermetallic coarsening and the appearance of intergranular fracture generated by dynamic recrystallization in the bulk solder joint. In this study, the influence of Bi content on the creep behaviors of solder joints was investigated under various aging conditions. Three lead-free solder alloys, including SAC305, SAC-3Bi, and SAC-6Bi, are tested at room temperature. For each alloy, preliminary micro-indentation tests were conducted to define three stress levels for distinct aging conditions. After each test, displacement versus time data was gathered. A novel approach based on an empirical model was developed to systematically examine the development of the steady-state creep rate. A power dependency prediction model was developed to investigate the relationship between creep strain rate and stress levels. The steady-state creep rate of SAC305 is significantly higher than that of SAC-Bi alloys owing to the presence of bismuth (Bi) in the solid solution at room temperature. The creep properties showed less variation after 100 h of aging. SAC-Bi alloys showed less coarsening of the intermetallic compounds precipitates after aging than SAC305. In the SAC-Bi solder alloys, combinations of precipitate and solid solution hardening mechanisms were observed, while Ag3Sn particles were the dominant strengthening mechanism in the SAC305 alloy system.

Integer linear programming-based optimization methodology for reliability and energy-aware high-level synthesis

Continuous decrease in the transistor technology sizes has enabled much denser packaging of electronic components on chips, which has resulted in integrated circuits with lower costs and area. However, it has also given rise to new issues and challenges in the process of integrated circuit design, including higher vulnerability to soft errors. Modular hardware redundancy is a popular method for improving the reliability of a system against errors at a cost of increasing area and energy consumption. Voltage scaling methods can be employed to tackle high energy costs; however, this also negatively affects the circuit’s reliability and performance. Therefore, designing circuits with all these conflicting parameters is a very challenging task. In this study, we propose integer linear programming (ILP)-based high-level synthesis (HLS) methods to optimize both reliability and/or energy under the area and latency constraints. Our models employ full and partial duplication to improve the system reliability as long as the area constraint permits. They also utilize voltage islands as the energy reduction method of choice. What makes this problem even more interesting and complex is the fact that we use different versions of the same resources that have different area, latency, reliability, and energy values. Although this affects the execution time of the proposed methods, it also gives us more design options. We compared and showed the effectiveness of our methods against a genetic algorithm-based one on several HLS benchmarks. The ILP-based methods return the optimum results most of the time under the given time limits.

Studies of mechanical, thermal and electrical properties of guar gum/carbon black composites

Polymers have proved to be an indispensable and integral part of our lives. However, prolonged and extensive use of these non-degradable polymers obtained from the non-renewable fossil fuels has led to their accumulation into the environment causing a potential threat to lives. There is a hue and cry about the undesirable consequences of this single-use plastic that needs an immediate answer. The present work contributes to the understanding of conductive polymer composites (CPC) packaging films for electronic goods. The replacement of the polymers used in the packaging of electronic components with bio-based biodegradable polymer films has been attempted. The carbon black was incorporated at varying weight percentages (0.01 to 0.2 wt. %) in the guar gum and the final films were evaluated using FTIR, XRD, DSC and TGA. The electrical properties were evaluated in terms of quality factor, resistance and dissipation factor.

Microstructure and shear fracture behavior of Mo/AlN/Mo symmetrical compositionally graded materials

The metallization of AlN ceramic is a critical prerequisite for applying AlN ceramics to electronic component packaging. In this study, a concept of functionally graded materials (FGMs) was used for the metallization of AlN ceramic. Symmetrical Mo/AlN/Mo FGMs with different composition exponent p (p=1, p<1, and p>1) were designed and fabricated by hot-press sintering. The influence of the p-value on the shear performance and fracture path of the Mo/AlN/Mo FGMs was investigated. Compared to specimens with p=1, the specimens with p<1 and p>1 show the distribution of Mo-rich and AlN-rich in the graded transition layer, respectively. The shear strength of the specimens reaches a maximum value of 48.0 MPa as p < 1 and 22.5 MPa higher than the minimum value as p > 1. Besides, three fracture paths were found for the Mo/AlN/Mo FGMs with different values of p, including the cracks propagate obliquely along the axis in the graded transition layer, the cracks penetrate through the AlN ceramic and the graded transition layer, and the cracks only propagate horizontally in a single graded layer. The crack initiation of Mo/AlN/Mo FGMs depends on the strength of each graded layer. Moreover, the directions of fracture paths are closely related to the strength of the ceramic interlayer and the composition exponent p.

Synergistic Strengthening of Mechanical Properties and Electromagnetic Interference Shielding Performance of Carbon Nanotubes (CNTs) Reinforced Magnesium Matrix Composites by CNTs Induced Laminated Structure.

In this study, we reported a laminated CNTs/Mg composite fabricated by spray-deposition and subsequent hot-press sintering, which realized simultaneous enhancement effects on strength and electromagnetic interference (EMI) shielding effectiveness (SE) by the introduced CNTs and CNT induced laminated ‘Mg-CNT-Mg’ structure. It was found that the CNTs/Mg composite with 0.5 wt.% CNTs not only exhibited excellent strength-toughness combination but also achieved a high EMI SE of 58 dB. The CNTs increased the strength of the composites mainly by the thermal expansion mismatch strengthening and blocking dislocation movements. As for toughness enhancement, CNTs induced laminated structure redistributes the local strain effectively and alleviates the strain localization during the deformation process. Moreover, it could also hinder the crack propagation and cause crack deflection, which resulted in an increment of the required energy for the failure of CNTs/Mg composites. Surprisingly, because of the laminated structure induced by introducing CNTs, the composite also exhibited an outperforming EMI SE in the X band (8.2–12.4 GHz). The strong interactions between the laminated ‘Mg-CNT-Mg’ structure and the incident electromagnetic waves are responsible for the increased absorption of the electromagnetic radiation. The lightweight CNTs/Mg composite with outstanding mechanical properties and simultaneously increased EMI performance could be employed as shell materials for electronic packaging components or electromagnetic absorbers.

Laser-Induced Forward Transfer (LIFT) Technique as an Alternative for Assembly and Packaging of Electronic Components

Current trends in microelectronics chip bonding and assembly encompass ultra-fine pitch components with flexible form factors and advanced die-attach materials, which can sustain conformal strain without compromise in adhesion and reliability. These trends have highlighted the need for advanced microfrabrication technologies, which allow the on-demand digital fabrication of interconnections and die-attach bumps on chip carriers and interposers with challenging topographies. Laser printing, based on the laser induced forward transfer (LIFT) technique, has addressed such micromanufacturing challenges over the past decade. Several previous demonstrations of highly resolved and conformal interconnections for the bonding and packaging of micro and opto-electronic components are summarized in this paper. Latest advances in the laser printing and laser sintering of highly viscous nanopastes for achieving planar or three-dimensional (3D) structures consisting of Ag paste are demonstrated. The latter is achieved by stacking of arrays or bumps in a digital manner. The reported results verify that LIFT offers control over both the lateral and vertical dimensions. This control can facilitate the soldering process of heterogeneous components, whose pads have significant height and pitch dissimilarities. The applicability of LIFT in the fields of packaging and assembly of flexible and heterogeneous integration schemes, is further validated.

Cure Kinetics Modeling of a High Glass Transition Temperature Epoxy Molding Compound (EMC) Based on Inline Dielectric Analysis.

We report on the cure characterization, based on inline monitoring of the dielectric parameters, of a commercially available epoxy phenol resin molding compound with a high glass transition temperature (>195 °C), which is suitable for the direct packaging of electronic components. The resin was cured under isothermal temperatures close to general process conditions (165–185 °C). The material conversion was determined by measuring the ion viscosity. The change of the ion viscosity as a function of time and temperature was used to characterize the cross-linking behavior, following two separate approaches (model based and isoconversional). The determined kinetic parameters are in good agreement with those reported in the literature for EMCs and lead to accurate cure predictions under process-near conditions. Furthermore, the kinetic models based on dielectric analysis (DEA) were compared with standard offline differential scanning calorimetry (DSC) models, which were based on dynamic measurements. Many of the determined kinetic parameters had similar values for the different approaches. Major deviations were found for the parameters linked to the end of the reaction where vitrification phenomena occur under process-related conditions. The glass transition temperature of the inline molded parts was determined via thermomechanical analysis (TMA) to confirm the vitrification effect. The similarities and differences between the resulting kinetics models of the two different measurement techniques are presented and it is shown how dielectric analysis can be of high relevance for the characterization of the curing reaction under conditions close to series production.

Enhanced properties of UPE/ESOA partially bio-nanocomposites reinforced with chitosan functionalized graphene nanoplatelets: an innovative approach

The current study deals with the successful development of chitosan-functionalized graphene nanoplatelets (CS/GNPs) and their dispersion in the unsaturated polyester (UPE)/epoxidized soybean oil acrylate (ESOA) (80:20 w/w) blend system in different compositions of 0.3, 0.5 and 0.7 wt%. The resulting nanocomposite mixture was achieved by simple sonication method and pressed into a mould for fabrication of nanocomposite. The whole functionalization and nanocomposite preparation procedure were successfully tracked by FTIR, SEM and TEM. Nanocomposite with 0.5 wt% of CS/GNPs nanofiller has demonstrated it as the better candidate due to its optimum properties. Again for better comparison, a nanocomposite with 0.5 wt% raw GNPs was also fabricated and its properties were studied in detail. This relative study reported lower mechanical, dynamic mechanical, thermal and electrical conductivity values for 0.5 wt% raw GNPs than the corresponding CS/GNPs nanofiller-filled nanocomposites. Nanocomposite with 0.5 wt% CS/GNPs showed dramatic enhancement in mechanical, dynamic mechanical, thermal and electrical properties as well as reduced corrosion and swelling performance owing to the homogeneous distribution of nanofiller in the blend. Again, the nanocomposite showed the highest thermal and electrical conductivities with the best dielectric strength. Thus, the prepared nanocomposites with optimum nanofiller content might serve as partially biodegradable nanomaterial for applications in nanotechnology engineering, thermal applications, such as circuit boards and electrical applications, such as electronic packaging components, electromechanical devices and electric energy storage devices. This nanocomposite can also find their applications in different corrosive- and solvent-based environments.

RIESGOS DE DESCARGAS ELECTROSTÁTICAS Y HUMEDAD EN LOS PROCESOS DE MANIPULACION ALMACENAMIENTO Y EMBALAJE EN LA INDUSTRIA ELECTRÓNICA

It presents a simple and practical method, which allows controlling the risks associated with electrostatic discharge (ESD) and humidity (MSD), in the productive processes of handling storage and packaging of electronic components, using SAP software (Systems, Applications and Product ) Implemented in an ERP (Enterprise Resource Planning) production planning system.

Defeating counterfeiters with microscopic dielets embedded in electronic components

Supply-chain traceability and electronics counterfeiting have become increasingly widespread issues for military and commercial electronics systems. In response to a DARPA SHIELD program directive, Northrop Grumman is leading a team to develop tiny, passive, near-field RFID chips, called dielets, which will be embedded in electronic component packaging. The design and implementation of dielets minimizes costs for electronics manufacturers while maximizing the security of the electronics supply chain.

Using Taguchi method to obtain the optimal design of heat dissipation mechanism for electronic component packaging

Packaging technology developments in semiconductor chips are moving towards miniaturization, thinner products, lighter weights, and higher performance. However, in the process of packaging, warpage and residual stress have always been major problems, such as pin deviation, breakage, and weak signals. Further, the distinctive properties of the numerous materials that comprise a semiconductor chip demand different molding temperatures; thus, excessive internal thermal stresses are produced within the packaging structure which ultimately results in colloid warpage. This study used a 3D coordinate measuring machine to determine the levels of warpage produced in electronic packaging products and to verify the amount of warpage simulated by the finite element method. Then, Taguchi method was also utilized to analyze and discuss the four critical control factors namely: (1) shape of the heat sink; (2) thickness of molding; (3) molding temperature; and (4) thickness of soldering tin. Thus, the minimum thermal stress for electronic packaging components was obtained, which meant the optimal parameter combination for the packaging was a triangle-shaped heat sink, with a molding compound of 1.175mm thick, a molding temperature of 170°C, and a soldering tin that was 0.03mm thick.

A review on reliability of electronic packaging in micro/nano manufacturing

Electronic packaging is a critical part of products such as computers, smart phones, automotive components and other electronic devices. Along with the development of society and economy, the demand for electronic devices and its quality has increased rapidly in recent years. Thus, it is necessary to research the reliability of electronic packaging. This paper presents a review of recent investigations on the reliability of electronic packaging components. The dynamic characteristics and fatigue test under different loading conditions are discussed, including vibration loading, thermal loading and combined loading. Finite element method (FEM) is used frequently in the studies as well as experimental test. Finally, it is significant to emphasise the importance of electronic packaging.

Stress relaxation behavior and low cycle fatigue behavior of bulk SAC 305

Solder plays a critical role in packaging because it serves several functions including electrical contacts, mechanical support, adhesion, and signal interconnections. In an attempt to reduce both the environmental and health concerns with using Pb lead based components in electronic packaging, legislation has been passed. One of the main alloys that is used as lead free solder material is SnAgCu (SAC) in varying compositions for several reasons. Fatigue Studies of SAC 305 solder samples in various geometries specific for microelectronic packaging has been performed [1–3]. However, there is a need to study the bulk material properties to further understand the performance of SAC 305 in a non-microelectronics setting. Some fatigue studies involving bulk solder have been conducted [4–9], but more work needs to be performed to completely understand the behavior of SAC 305.

Enhanced heat transfer through filler-polymer interface by surface-coupling agent in heat-dissipation material: A non-equilibrium molecular dynamics study

Developing a composite material of polymers and micrometer-sized fillers with higher heat conductance is crucial to realize modular packaging of electronic components at higher densities. Enhancement mechanisms of the heat conductance of the polymer-filler interfaces by adding the surface-coupling agent in such a polymer composite material are investigated through the non-equilibrium molecular dynamics (MD) simulation. A simulation system is composed of α-alumina as the filler, bisphenol-A epoxy molecules as the polymers, and model molecules for the surface-coupling agent. The inter-atomic potential between the α-alumina and surface-coupling molecule, which is essential in the present MD simulation, is constructed to reproduce the calculated energies with the electronic density-functional theory. Through the non-equilibrium MD simulation runs, we find that the thermal resistance at the interface decreases significantly by increasing either number or lengths of the surface-coupling molecules and that the effective thermal conductivity of the system approaches to the theoretical value corresponding to zero thermal-resistance at the interface. Detailed analyses about the atomic configurations and local temperatures around the interface are performed to identify heat-transfer routes through the interface.

Characterization of the viscoelastic properties of an epoxy molding compound during cure

In the electronics industry epoxy molding compounds, underfills and adhesives are used for the packaging of electronic components. These materials are applied in liquid form, cured at elevated temperatures and then cooled down to room temperature. During these processing steps residual stresses are built up resulting from both cure and thermal shrinkage. These residual stresses add up to the stresses generated during thermal cycling and mechanical loading and may eventually lead to product failure.The viscoelastic properties of the encapsulation material depend highly on temperature and degree of cure. This paper investigates the increase of elastic modulus and the changes in the viscoelastic behavior of an epoxy molding compound, during the curing process. This is done using the shear setup of a Dynamic Mechanical Analyzer DMA-Q800. The cure dependent viscoelastic behavior is determined during heating scans of an intermittent cure experiment. In such an experiment the material is partially cured and then followed by a heating scan at 2°C/min. During this heating scan continuous frequency sweeps are performed and the shear modulus is extracted. The Time–Temperature superposition principle is applied and the viscoelastic shear mastercurve is extracted. Analyzing the shear modulus, the cure dependent viscoelastic material behavior was modeled using the cure dependent glass transition temperature as a reference and a cure dependent rubbery modulus. It is shown that partial curing would increase the glass transition temperature and rubbery shear modulus. It also shifts the viscoelastic mastercurve to the higher time domain. Taking Tg as the reference temperature for different heating scans, the mastercurves collapse to one graph.In addition, using a Differential Scanning Calorimeter (DSC), the growth of the glass transition temperature, TgDSC, with respect to the conversion level is obtained. These values are coupled to the values of glass transition temperature in DMA apparatus, TgDMA, for calculating the conversion level at each step of curing process in shear mode test.

Recycling of Thermosetting Epoxy Molding Compound Waste into PVC Composites: Effect of Silane Coupling Agent on Morphology and Physical Properties

The aim of this study was to investigate the recycling of waste cured epoxy molding compound (c-EMC) which was generated as the mold residue in molding process of electronic component packages, by way of blending the pulverized mold residue with poly (vinyl chloride) (PVC) and other additives to prepare a reproduction composite. The influence of modified and non-modified c-EMC powder on structure and properties of the composites were analyzed by mechanical tests, vicat softening point test (VST) and scanning electron microscopy (SEM). The results showed that simple adding c-EMC powder could improve the stiffness and heat resistance of the composites, though decreased the mechanical strength of the composites. After being pretreated by silane coupling agent γ-aminopropyltriethoxysilane (KH-550), modified c-EMC powder had effective strengthening and toughening effects on the composites with the increasing powder content. Furthermore, better interfacial adhesion and higher VST value of the composites were observed in the presence of KH-550.

Thermal Design Methodology for an Embedded Power Electronic Module Using Double-Sided Microchannel Cooling

This paper presents a thermal design methodology for an integrated power electronic module (IPEM) using embedded, single-phase, and laminar-flow rectangular microchannels. Three-dimensional packaging of electronic components in a small and compact volume makes thermal management more challenging, but IPEMs also offer the opportunity to extract heat from both the top and the bottom side of the module, enabling double-sided cooling. Although double-sided cooling of IPEMs can be implemented using traditional aluminum heat sinks, microchannels offer much higher heat transfer coefficients and a compact cooling approach that is compatible with the shrinking footprint of electronic packages. The overall goal of this work was to find the optimal microchannel configuration for the IPEM using double-sided cooling by evaluating the effect of channel placement, channel dimensions, and coolant flow rate. It was found that the high thermal conductivity copper of the direct bonded copper (DBC) layer is the most feasible location for the channels. Based on a new analytical heat transfer model developed for microchannels in IPEM structures, several design configurations were proposed in this study that employ the microchannels in the copper layers of the top and bottom DBCs. The designs included multiple parallel channels in copper as well as a single wide microchannel. The analytical model was verified using a finite element model, and the competing design configurations were compared against a commercial cooler. For a typical IPEM structure dissipating on the order of 100W of heat, it was concluded that a single microchannel DBC heat sink is preferable to multiple parallel channels under a double-sided cooling configuration, considering thermal performance, pressure drop and fabrication trade-offs.