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The purpose of this paper is to describe a novel method for the manufacture of aluminum rigid‐flex circuit assemblies without the use of solder.

The approach involves the use of an aluminum base material and the embedding of components, while avoiding the use of solder in the assembly process.

The new methods and proposed structures address the key manufacturing problems that have vexed users for many years, while simultaneously addressing the challenge of thermal management. They also offer the advantage of enhanced reliability by avoiding the need for high temperatures used in soldering.

While examples of the process and its benefits have been demonstrated, further work is ongoing to expand applicability.

The paper begins with an overview of previous work in this area and then moves on to what is currently being implemented via the new technology. A novel method is described for the creation of potentially more cost‐effective and reliable rigid flex assemblies, which would be suitable for use in a wide range of products, from consumer to high‐reliability automotive, military and aerospace.

The purpose of this paper is to form good cutting qualities in glass-epoxy material for opening flexible areas of rigid-flex printed circuit boards (PCB) by ultraviolet (UV) laser cutting.

The cut width and cut depth of glass-epoxy materials were both observed to evaluate their cutting qualities. The heat affected zone (HAZ) of the glass-epoxy material was also investigated after UV laser cutting. The relationships between the cut width and the parameters of various factors were analyzed using an orthogonal experimental design.

The cut width of the glass-epoxy material gradually increased with the increment of the laser power and Z-axis height, while cutting speed and laser frequency had less effect on the cut width. Optimal parameters of the UV laser process for cutting glass-epoxy material were obtained and included a laser power of 6W, a cutting speed of 170 mm/s, a laser frequency of 50 kHz and a Z-axis height of 0.6 mm, resulting in an average cut width of 25 μm and small HAZ.

Flexible areas of rigid-flex PCBs are in good agreement with the cutting qualities of the UV laser. The use of a UV laser process could have important potential for cutting glass-epoxy materials used in the PCB industry.

Polymer thick film (PTF) technology provides the lowest cost, cleanest and most efficient manufacturing method for producing flexible circuits. Non‐contact radio frequency (RF) smart cards and related information transaction devices, such as RFID tags, appear to be a good fit for PTF‐flex. Flip chip also seems well suited for these “contactless” RF transceiver products. Flip chip and PTF adhesive technologies are highly compatible and synergistic. All PTF SMT adhesives assembly methods are viable for flip chip. However, the merging of flip chip with PTF‐flex presents major challenges in design, materials and processing. This paper will compare assembly methods and discuss obstacles and solutions for state‐of‐the‐art flip chip on flex within the RFID product environment.

Hand motor dysfunction has seriously reduced people’s quality of life. The purpose of this paper is to solve this problem; different soft exoskeleton robots have been developed because of their good application prospects in assistance. In this paper, a new soft hand exoskeleton is designed to help people conduct rehabilitation training.

The proposed soft exoskeleton is an under-actuated cable-driven mechanism, which optimizes the force transmission path and many local structures. Specifically, the path of force transmission is optimized and cables are wound around cam-shaped spools to prevent cables lose during fingers movement. Besides, a pre-tightening system is presented to adjust the preload force of the cable-tube. Moreover, a passive brake mechanism is proposed to prevent the cables from falling off the spools when the remote side is relaxed.

Finally, three control strategies are proposed to assist in rehabilitation training. Results show that the average correlation coefficient of trajectory tracking is 90.99% and this exoskeleton could provide steady clamping force up to 35 N, which could meet the demands of activities in daily living. Surface electromyography (sEMG)-based intention recognition method is presented to complete assistance and experiments are conducted to prove the effectiveness of the assisted grasping method by monitoring muscle activation, finger angle and interactive force.

However, the system should be further optimized in terms of hardware and control to reduce delays. In addition, more clinical trials should be conducted to evaluate the effect of the proposed rehabilitation strategies.

May improve the ability of hemiplegic patients to live independently.

A novel under-actuated soft hand exoskeleton structure is proposed, and an sEMG-based auxiliary grasping control strategy is presented to help hemiplegic patients conduct rehabilitation training.

This study presents a method for fabricating multi-material objects using a hybrid additive and subtractive approach. By hybridizing the material composition in addition to the fabrication process, functional requirements can be met more effectively than through homogenous material parts produced using a single manufacturing process. Development of multi-material objects consisting of dissimilar materials that have been hampered by a lack of a structural interface compatible with in-envelope hybrid additive and subtractive manufacturing.

This research presents a novel method for producing multi-material components through in-envelope hybrid additive and subtractive manufacturing. This study attempts to address the absence of a metal-polymer interface by integrating polymer additive manufacturing into a five-axis mill. The ability of the polymer additive system to reproduce overhang geometries is assessed with different levels of cooling. The relationship between structural performance, cooling and material flow rate is evaluated for the deposited carbon fiber reinforced acrylonitrile butadiene styrene.

A mechanically interlocking root structure is developed to form an interface between a machined aluminum region and a polymer region of an object. The tensile strength of the metal-polymer object is measured and found to be on the same order of magnitude as the bulk three-dimensional printed polymer.

By targeting the material properties to the local functional requirements within a part and taking advantage of both additive and subtractive manufacturing processes, this study will enable broader design options and optimization of performance metrics.

Polymer substrates with micron size roughness features have been found to play an important role in the mechanical performance of thin functional films which are used extensively in stretchable and flexible micro electromechanical systems. The purpose of this study is to report the stretchability and flexibility limits of micro size silver nano platelet films on a soft polymer substrate having two different orientations of micro grating with respect to the applied load.

Parallel and perpendicular micro gratings on the surface of a soft polymer substrate polydimethylsiloxane were patterned using a carefully machined master aluminum block and thin aluminum foils. Silver nano platelet-based films were rod coated on the substrate surface containing the micro gratings. These films were dried in ambient air and were tested for their stretchability and flexibility limits using homemade tools. Finite element modeling has also been performed and was found to support the experimental observations.

Experiments indicate that stretchability of silver nano platelet-based thin films tends to increase when the grating orientation remains parallel to the axis of the applied load, while its flexibility improves when the orientation becomes perpendicular to the loading axis.

The effect of grating orientation with respect to the applied load was investigated. The experiments show that micro grating roughness features are capable of enhancing the mechanical performance of nano platelet-based silver films on a soft polymer substrate and can be used in various stretchable and flexible micro electro mechanical device applications.

Modern semiconductor technologies have advanced to the level of sophistication where the benefits of the high functional and power density, high speed, low defect rate and low wafer processing cost can seldom be fully utilised at the final equipment or even at the single packaged semiconductor component level due to the limitations of wire bonds and lead frame fan‐outs. This paper suggests a new assembly method where low‐cost contact bumps are deposited on semiconductor wafers and then the dice are reflow soldered or gang bonded to the substrate. The bumps are electroless nickel deposited and coated with a protective layer of gold. As the nickel bumps are non‐collapsible, they are better suited to Extra High Density Interconnections (EHDI) than the more usual solder bumps. The amount of solder must be accurately dispensed either on the die bumps or on the substrate bonding pads using various methods. Essential to the high volume assembly is fast pick‐and‐place operation and simultaneous soldering of all components in a reflow furnace. In certain applications bonding of the bumped device (one die at a time) can be done using reflow or thermocompression gang bonding by applying a heated thermode to the backside of the die. In this case, the bonding energy will be transferred through the die to the bumps. Tentative solder joint strength and reliability aspects are discussed. Further process and design improvements are suggested.

This paper aims to present the design of a cantilever beam with various kinds of geometries for application in energy harvesting devices with a view to enhance the harvested power. The cantilever beams in rectangular, triangular and trapezoidal geometries are simulated, designed and evaluated experimentally. A power conditioning circuit is designed and fabricated for rectification and regulation.

The analytical model based on Euler–Bernoulli beam theory is analyzed for various cantilever geometries. The aluminum beam with Lead Zirconate Titanate (PZT) 5H strip is used for performing frequency, displacement, strain distribution, stress and potential analysis. A comparative analysis is done based on the estimated performance of the cantilevers with different topologies of 4,500 mm³ volume.

The analysis shows the trapezoidal cantilever yielding a maximum voltage of 66.13 V at 30 Hz. It exhibits maximum power density of 171.29 W/mm³ at optimal resistive load of 330 kΩ. The generated power of 770.8 µW is used to power up a C-mote wireless sensor network.

This study provides a complete structural analysis and implementation of the cantilever for energy harvesting application, integration of power conditioning circuit with the energy harvester and evaluation of the designed cantilevers under various performance metrics.

This study seeks to examine the advantages of mildly alkaline immersion silver as a final finish for solderability in order to combat the shortcomings of acidity in some popular immersion silver solutions.

The paper describes in detail the necessary steps in the mildly alkaline immersion silver process.

The process can overcome the problems of conventional acidic immersion silvers, especially in thermal shock and stress testing. Also it does not affect soldering or aluminium wire bonding.

This is arguably a pioneering study in that it posits the benefits of mildly alkaline immersion silver as a final finish for solderability.

The purpose of this paper is to present design and analysis of a novel earpiece‐less eyeglass frame.

A virtual assembly process was used to test the part design and finally a prototype was built to check the design.

Earpiece‐less eyeglasses are easier to adjust for higher comfort levels and do not incorporate leg hinges compared to traditional eye‐glasses. This novel design is unique and will be in mass production.

This paper presents a novel earpiece‐less eyeglasses frame design and will have significant impact to the market.