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The purpose of this paper is to evaluate and exploit the combination of additive manufacturing polymeric technology and structural adhesives. The main advantage is to expand the maximum dimension of the 3D printed parts, which is typically limited, by joining the parts with structural adhesive, without losing strength and stiffness and keeping the major asset of polymeric 3 D printing: freedom of shape of the system and low cost of parts.

The materials used in the paper are the following. The adhesive considered is a commercial inexpensive acrylic, quite similar to superglue, applicable with almost no surface preparation and fast curing, as time constraint is one of the key problems that affects industrial adhesive applications. The 3D printed parts were in acrylonitrile butadiene styrene (ABS), obtained with a Fortus 250mc FDM machine, from Stratasys. The work first compares flat overlap joint with joints designed to permit mechanical interlocking of the adherends and then to a monolithic component with the same geometry. Single lap, joggle lap and double lap joints are the configurations experimentally characterized following a design of experiment approach.

The results show a failure in the substrate, due to the low strength of the polymeric adherends for the first batch of typical bonded configurations, single lap, joggle lap and double lap. The central bonded area, with an increased global thickness, never does fail, and the adhesive is able to transfer the load both with and without mechanical interlocking. An additional set of scarf joints was also tested to promote adhesive failure as well as to retrieve the adhesive strength in this application. The results shows that bonding of polymeric AM parts is able to express its full potential compared with a monolithic solution even though the joint fails prematurely in the adherend due to the bending stresses and the notches present in the lap joints.

Because of the 3D printed polymeric material adopted, the results may be generalized only when the elastic properties of the adherends and of the adhesive are similar, so it is not possible to extend the findings of the work to metallic additive manufactured components.

The paper shows that the adhesives are feasible way to expand the potentiality of 3 D printed equipment to obtain larger parts with equivalent mechanical properties. The paper also shows that the scarf joint, which fails in the adhesive first, can be used to extract information about the adhesive strength, useful for the designers which have to combine adhesive and additive manufactured polymeric parts.

To the best of the researchers’ knowledge, there are scarce quantitative information in technical literature about the performance of additive manufactured parts in combination with structural adhesives and this work provides an insight on this interesting subject. This manuscript provides a feasible way of using rapid prototyping techniques in combination with adhesive bonding to fully exploit the additive manufacturing capability and to create large and cost-effective 3 D printed parts.

Adhesively bonded joints are used in many fields, especially in the automotive, marine, aviation, defense and outdoor industries. Adhesive bonding offers advantages over traditional mechanical methods, including the ability to join diverse materials, even load distribution and efficient thermal-electrical insulation. This study aims to investigate the mechanical properties of adhesively bonded joints, focusing on adherends produced with auxetic and flat surfaces adhered with varying adhesive thicknesses.

The research uses three-dimensional (3D)-printed materials, polyethylene terephthalate glycol and polylactic acid, and two adhesive types with ductile and brittle properties for single lap joints, analyzing their mechanical performance through tensile testing. The adhesion region of one of these adherends was formed with a flat surface and the other with an auxetic surface. Adhesively bonded joints were produced with 0.2, 0.3 and 0.4 mm bonding thickness.

Results reveal that auxetic adherends exhibit higher strength compared to flat surfaces. Interestingly, the strength of ductile adhesives in auxetic bonded joints increases with adhesive thickness, while brittle adhesive strength decreases with thicker auxetic bonds. Moreover, the auxetic structure displays reduced elongation under comparable force.

The findings emphasize the intricate interplay between adhesive type, bonded surface configuration of adherend and bonding thickness, crucial for understanding the mechanical behavior of adhesively bonded joints in the context of 3D-printed materials.

The concept of an air‐gap insulated piston has been explored using bolted and welded/roll bonded designs. Pistons with bolted‐on crowns demonstrated the effectiveness of air gap insulation, but roll bonded and welded designs were found to be more robust and to provide the complete sealing of the air gap necessary for continued insulation. Evolution of the design to combine high insulation with adequate durability is discussed. Engine running times of up to 200 hours at full load have been achieved for an air gap piston which reduces heat flow to the crown by 33 per cent. An improved design giving 41 per cent reduction of heat flow has been tested for 78 hours at full engine load with no evident deterioration. Development is continuing to provide a fully durable piston achieving up to 50 per cent reduction in heat flow.

A review of state‐of‐the‐art technology pertinent to tape automated bonding (for fine pitch, high I/O, high performance, high yield, high volume and high reliability) is presented. Emphasis is placed on a new understanding of the key elements (for example, tapes, bumps, inner lead bonding, testing and burn‐in on tape‐with‐chip, encapsulation, outer lead bonding, thermal management, reliability and rework) of this rapidly moving technology.

This paper examines how bonded design (BD), a participatory design methodology, was influenced by the transition to working in a virtual environment necessitated by the coronavirus disease 2019 (COVID-19) pandemic.

Abiding by the participatory design tenets of creativity, learning-by-doing and mutual learning, the BD methodology was created for the specific purpose of fostering meaningful communication and interaction between two disparate groups. Previous iterations of BD are discussed, including its naissance with intergenerational teams, its adaptation to provide a framework for a university-wide initiative, the Faculty Information Technology (IT) Liaison Program that brought together faculty members and IT professional staff, and its current use in helping public librarians to develop with older adults, targeted library programming and services.

Analysis of the findings from the assessment of the BD methodology in different physical contexts demonstrates that the flexibility in the makeup and order of design techniques (discussion, evaluation, brainstorming, prototyping, consensus-building) makes BD potentially adaptable to online spaces. Recommendations for implementing the BD methodology online are outlined. It is argued that BD’s adaptability makes it an ideal method for creating meaningful and productive collaborations within both physical and virtual environments.

The proposed iteration of the BD methodology responds to a need for innovative practices to foster collaborative work in a virtual environment. BD is a unique, inclusive and cost-effective methodology to encourage meaningful interaction and communication between disparate groups in physical or online contexts.

ESTABLISHING A STANDARD SOME twenty‐two years ago Dr de Bruyne invented the Redux system for joining metal to metal in a manner suitable for use in aircraft construction The phenol‐formaldehyde/polyvinyl‐formal formulation of this system is still widely used today. What is it that has made this system such a success through the years?

At present, over 95 percent of the manufactured packages are still being wire bonded. Owing to the ongoing trend of miniaturization, material changes, and cost reduction, wire bond‐related failures are becoming increasingly important. This paper aims to understand these kinds of failures.

Different finite element (FE) techniques are explored to their ability to describe the thermo‐mechanical behavior of the wire embedded in the electronic package. The developed nonlinear and parametric FE models are able to predict the strong nonlinear behavior of wire failures and multi‐failure mode interaction accurately and efficiently.

It is found that both processing and testing environments as well as the occurrence of delamination strongly increase the risk for wire failures. The results indicate that processing and testing influences are much less than those of the delamination.

Package designers should focus on limiting the occurrence of delamination around wire bond and/or stitch areas.

Combining the strengths of predictive modeling with simulation‐based optimization methods, the optimal wire shape is obtained.

The purpose of this paper was to attempt to confirm the root cause of unstable stitch pull strength in PQFN package and propose some permanent solutions for it.

A screen experiment was designed to find the key process out of the manufacturing flow; a non‐destructive detaching method and cross section polishing were used to inspect the bond integrity; Auger analysis assisted with argon ion sputter was tried to confirm the contamination; finally the manufacturing processes were redesigned to prevent the contamination.

Some first aids of process optimization got little improvement; the screen experiment of processes found solder die bonding was the one resulted into a poor bond integrity which was demonstrated by non‐destructive detaching method and cross section inspection; Auger analysis assisted with argon ion sputter detected that there was a tin layer thicker than 20 nm coated on the bonding surface and the wire bondability of gold wire on this tin coating was poor; the lead frame was redesigned to prevent the wetting and flowing of tin and got a perfect performance.

Because of the limitation of time and resources, the proposed solutions for this issue could be studied more deeply.

This paper set up an example how to find out the root cause from the complex manufacturing process flow and put forward a quick solution accordingly for the issue.

Known good die, flip chip and chip scale packages are technologies that offer various advantages to the board manufacturer. A discussion of the different types of package options, their methods of assembly, test and performance comparisons can help to resolve the general direction a manufacturer might pursue for next generation systems. This paper attempts to give a perspective as well as highlighting the areas of concern with the different options.

The reliability of chip‐on‐film (COF) packages is fundamentally dependent upon the quality of the eutectic Au‐Sn joint formed between the Au bumps on the integrated circuit (IC) device and the Sn‐plated Cu inner leads. Therefore, it is essential that an appropriate bonding temperature is achieved during the inner lead bonding (ILB) process. The purpose of this paper is to identify the optimal processing conditions which maximize the reliability of the Au‐Sn joints.

The paper commences by performing an experimental investigation to establish the temperature at three specific locations within the COF/ILB system in a typical gang‐bonding process. The relationship between the setting temperature of the bonding tool and the temperature of the tool surface is then calibrated using an off‐line experimental system. An ANSYS finite element (FE) model is then constructed to simulate the temperature distribution within the COF/ILB system under representative temperature conditions. The validity of the numerical model is confirmed by comparing the simulation results with the experimental temperature measurements. The FE model is then used in a 2³ factorial design process to evaluate the effect of the principal COF/ILB processing parameters, namely the contact area, the tool temperature and the stage temperature, on the temperature induced at the interface between the Au bumps on the IC chip and the Sn‐coated Cu leads on the polyimide film.

The results reveal that the interfacial bonding temperature is determined primarily by the stage temperature.

A regression analysis model is applied to the factorial design results to construct a COF/ILB design chart which enables the rapid identification of the stage and tool temperatures required to achieve the minimum feasible eutectic bonding temperature.