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Reviews the traditional use of thermoset (epoxy) adhesives for various bonding applications and highlights some limitations in today’s microelectronics arena. In particular, concerns for thermal and stress management associated with large area silicon bonded to a wide variety of substrate materials has led to an increasing interest in thermoplastic adhesive technology. Thermoplastics are not always the best solution for every application. This paper sets out to address the “pros and cons” of each polymer technology for different microelectronic applications taking into account some of the key physical properties such as Tg, TCE and modulus. In addition, practical issues such as handling, storage and processing are considered in detail.

This paper seeks to give an overview on the benefits and challenges of moulded interconnect devices‐technology and the use of flexible printed circuits (FPC) in electronics production.

Each process step was adapted to the boundary conditions of manufacturing three‐dimensional substrates and FPC. The substrate materials were examined under the specific requirements of electronics production with a special focus on the thermal stability of the materials and the adhesiveness of the metallization.

The use of thermoplastics as substrate materials for electronic devices offers high potential but new challenges, e.g. the higher coefficient of thermal expansion of thermoplastics, have to be taken into consideration as well. In most cases, standard machines for surface mount technology can be used with few modifications. Research has shown that even components with very fine pitches can be used successfully on alternative substrate materials.

The paper covers a selection of possible thermoplastic materials that can be used in electronics production. Depending on the requirements of the application and the operating environment other substrate materials open up a large variety of possible solutions.

The paper details the most promising thermoplastic materials for use in electronics production as rigid and FPC. Furthermore, it gives information about manufacturing guidelines for the production of three‐dimensional circuit carriers.

Today’s emerging markets in the electronic packaging industry require some unique properties in adhesives, especially in die attach applications. In multichip module (MCM) applications, for example, the low temperature reworkability of die bonds is of primary importance, particularly if known good die (KGD) are not employed. If KGD are used in the MCM, a temporary, reworkable die adhesive is also desirable for a KGD testing programme. Large area die on organic substrates, which are key to the more portable, high power computers, require a very compliant adhesive to absorb the high mismatch in expansions. An overview of the present adhesive technologies reveals some serious limitations in their application and performance. Traditional Ag epoxies, primarily because of their irreversible ‘thermosetting’ during cure, do not fulfill all the material requirements. Thermoplastic chemistries are ideal candidates for MCMs because of their reversible melting and resolidification properties. This paper details the development of a novel silver loaded thermoplastic paste that overcomes most of the deficiencies seen in present day adhesives. One of the main obstacles that has hindered the use of thermoplastic pastes as an adhesive has been the slow solvent extraction during the curing step. With current technology, this inherently slow solvent extraction typically requires a complex process of first depositing a flat profile, then removing the solvent with a pre‐drying step, and finally attaching the die by a heat/pressure step. A blend of components, hereafter referred to as DM4030, has been tested and compared against conventional materials in the industry. Functional properties of adhesion, resistivity, wire bonding and others are summarised for various temperature profiles. Long‐term reliability test results are shown for temperature cycling, temperature/humidity (85° C, 85% RH), and high temperature storage. For reworkability applications, die removal force as a function of temperature is also presented.

Since the development of electrostatic powder spraying, powders based on epoxy resins have been the ones predominantly used. These powders have worked well in many cases and can be used for decorative as well as functional coatings. These coatings due, to the chemical nature of epoxy resins, are ‘thermosetting’. This means they not only undergo a physical change when heated, that causes them to melt and flow but they also undergo a chemical change that causes them to increase in molecular weight or ‘crosslink’. Once this happens they cannot be remelted if heated a second time. Due to the wide use of epoxy powders many people associate powder coating with thermosetting powder.

The purpose of this paper is to investigate the feasibility to produce a novel aircraft full stiffened panel using entirely a new hybrid thermoplastic composite material allowing for appreciably lower processing temperatures as compared to conventional structural thermoplastic composites.

For stiffening the fuselage skin panel, the out of autoclave welding of four composite stringers was obtained using a modified induction welding (IW) process. The quality of the welds was investigated using micro-tomography and the mechanical strength of the lap joints was assessed by means of single-lap shear strength (SLSS) tests. Moreover, a holistic design index was implemented as a decision support tool for selecting the optimal set of IW process parameters. Based on the index used, the quality as well as the entire life cycle cost and environmental impact are accounted for.

Low porosity values as well as no deconsolidation were observed at the investigated application, and the average measured SLSS, even found lower, lies within the range of the respective values encountered in other similar high-performance applications. It is exhibited that after the optimization, the IW process offers significant potential to replace the autoclave process in welding applications. Thus, it paves the way for reduced cost and increased sustainability, while still meeting the predefined quality constraints.

Although several studies on the IW application have been conducted, limited results exist by using novel thermoplastic materials for aircraft structural applications.

This research work aims to determine the maximum load a thermoplastic gear can withstand without the occurrence of extended contact. The extended contact of polymer gears is usually overlooked in basic design calculations, although it considerably affects the gear's load-carrying ability. Although various researchers highlighted the phenomenon, an extensive investigation of the extended contact behaviour is limited. Hence the work aims to investigate the premature and extended contact behaviour of thermoplastic gears and its effect in the gear kinematics, bending stiffness, stresses induced and the roll angle subtended by the gear pair.

The work uses finite element method to perform quasi-static two-dimensional analysis of the meshing gear teeth. The FE model was developed in AutoCAD and analysed using ANSYS 19.1 simulation package. A three-dimensional gear model with all the teeth is computationally intensive for solving a static analysis problem. Hence, planar analysis with a reduced number of teeth is considered to reduce the computational time and difficulty.

The roll angle subtended at the centre by the path of approach is higher than the path of recess because of the increased load sharing. The contact stress profile followed a unique R-F-R-F pattern in the premature and extended contact regions due to the driven tip-driver flank surface contact. A non-dimensional parameter was formulated correlating the young's modulus, the load applied and deflection induced that can be utilised to predict the occurrence of premature and extended contact in thermoplastic gears.

The gear rating standards for polymer gears are formulated from the conventional metal gears which does not include the effect of gear tooth deflection. The work attempts to explain the gear tooth deflection for various standard thermoplastics and its effect in kinematics. Likewise, a new dimensionless number was introduced to predict the extended contact that will help in appropriate selection of load reducing the possibility of wear.

This paper aims to detail the qualification of alternative substrate materials and reliability aspects for quad flat no lead (QFN) packages for highly stressed electronic devices, e.g. for use in automotive applications.

Detailed information is given on the advanced climatic and mechanical requirements that electronic devices have to withstand during life cycle testing to qualify for the automotive industry. Studies on the suitability of high‐temperature thermoplastics as substrate materials for printed circuit boards and the qualification of QFN packages for advanced requirements are described. In addition, information on cause‐effect relationships between thermal and vibration testing are given.

With respect to adhesion of metallization on high‐temperature thermoplastics and the long‐term stability of the solder joints, these substrate materials offer potential for use in electronic devices for advanced requirements. In addition, the long‐term stability of the solder joints of QFN packages depends on the design of the landings on the PCB and the separation process of the components during manufacturing.

The paper covers only a selection of possible high‐temperature thermoplastic materials that can be used in electronics production. Also, this paper has a focus on the new packaging type, QFN, in the context of qualification and automotive standards.

The paper details the requirements electronic devices have to meet to be qualified for the automotive industry. Therefore, this contribution has its value in giving information on possible substrate alternatives and the suitability for the usage of QFN components for highly stressed electronic devices.

Continuous fiber reinforced thermoplastic composites (CFRTPCs) are becoming more significant in industrial applications but are limited by the high cost of molds, the manufacturing boundedness of complex constructions and the inability of special fiber alignment. The purpose of this paper is to put forward a novel three-dimensional (3D) printing process for CFRTPCs to realize the low-cost rapid fabrication of complicated composite components.

For this purpose, the mechanism of the proposed process, which consists of the thermoplastic polymer melting, the continuous fiber hot-dipping and the impregnated composites extruding, was investigated. A 3D printing equipment for CFRTPCs with a novel composite extrusion head was developed, and some composite samples have been fabricated for several mechanical tests. Moreover, the interface performance was clarified with scanning electron microscopy images.

The results showed that the flexural strength and the tensile strength of these 10 Wt.% continuous carbon fiber (CCF)/acrylonitrile-butadiene-styrene (ABS) specimens were improved to 127 and 147 MPa, respectively, far greater than the one of ABS parts and close to the one of CCF/ABS (injection molding) with the same fiber content. Moreover, these test results also exposed the very low interlaminar shear strength (only 2.81 MPa) and the inferior interface performance. These results were explained by the weak meso/micro/nano scale interfaces in the 3D printed composite parts.

The 3D printing process for CFRTPCs with its controlled capabilities for the orientation and distribution of fiber has great potential for manufacturing of load-bearing composite parts in the industrial circle.

This paper aims to present a survey concerning the accuracy of thermoplastic polymeric parts fabricated by additive manufacturing (AM). Based on the scientific literature, the aim is to provide an updated map of trends and gaps in this relevant research field. Several technologies and investigation methods are examined, thus giving an overview and analysis of the growing body of research.

Permutations of keywords, which concern materials, technologies and the accuracy of thermoplastic polymeric parts fabricated by AM, are used for a systematic search in peer-review databases. The selected articles are screened and ranked to identify those that are more relevant. A bibliometric analysis is performed based on investigated materials and applied technologies of published papers. Finally, each paper is categorised and discussed by considering the implemented research methods.

The interest in the accuracy of additively manufactured thermoplastics is increasing. The principal sources of inaccuracies are those shrinkages occurring during part solidification. The analysis of the research methods shows a predominance of empirical approaches. Due to the experimental context, those achievements have consequently limited applicability. Analytical and numerical models, which generally require huge computational costs when applied to complex products, are also numerous and are investigated in detail. Several articles deal with artificial intelligence tools and are gaining more and more attention.

The cross-technology survey on the accuracy issue highlights the common critical aspects of thermoplastics transformed by AM. An updated map of the recent research literature is achieved. The analysis shows the advantages and limitations of different research methods in this field, providing an overview of research trends and gaps.

The trend towards higher density, higher frequency, higher power active devices in placing increasingly difficult demands on device packaging. Materials with high thermal conductivities are replacing the traditional ceramics in hermetic, high power packages, and MCM/ hybrid modules. Thermally enhanced plastic packages more frequently feature heat sinks embedded in the package for direct attachment of the power devices. Today's challenge in electronic packaging is to dissipate the heat from the source, the device itself, without affecting its electrical performance or reliability. The material directly contacting the device is the die attach medium. On lower power packages, the die bond line is not usually the highest thermal resistance in the thermal path. With highly conductive substrates and heat sinks, the die attach material now becomes the critical element directly in series with the highly conductive substrate. Fundamental limitations in thermal properties of about 3 W/mK exist in present‐day organic adhesives, primarily of the thermosetting type. This thermal conductivity (k) does not meet the current demands of thermally enhanced plastic laminate packages, MCMs, or direct die attach to heat spreaders or heat sinks. This paper describes the development, properties and application of electrically conductive thermoplastic adhesive pastes having thermal conductivity values as high as 35 W/mK, and able to produce thin, void‐free bond lines for maximum thermal transfer. The key material variables are isolated and evaluated for their impact of the k value. DOEs (design of experiments) were run to optimise the combination of the key variables, namely size/shape of the filler and the volume fraction to produce the highest k without sacrificing other functional properties such as adhesion. The effect of polymer chemistry (thermoset and thermoplastic) was also studied. The properties of the newly developed, enhanced conductivity thermoplastic adhesives are compared with other material technologies and examples of current applications reviewed.