decade, substantial efforts were devoted to the research and development of the nextgeneration composites. This new class of materials should not only possess higher strength-to-weight ratio than metals but also tailored with integrated intelligence, which is desirable as infrastructures for next generation of "internet of things." Carbon nanomaterials, such as carbon nanotubes and carbon nanofibers, have received dominant attention for the creation of intelligent composites. [3][4][5][6] They were dispersed in a polymer matrix to form conductive percolating networks as distributed sensors in situ to evaluate the strain, stress, damage, and temperature for self-sensing and on-line structural health monitoring applications. [3][4][5][6] However, these composites are restricted to (piezo) resistive effect based sensing capabilities from the included nanomaterials. Nextgeneration composites, however, should not only encompass sensing capabilities but also be equipped with other functionalities such as lighting, computation, and communication elements, as illustrated in Figure 1. One straightforward solution to achieve this goal is to integrate electronic circuits with off-the-shelf components in the composites. However, these functional composites usually have complex, 3D shapes, but conventional electronic circuits are rigid and planar. The shape mismatch between 3D composites and planar, rigid electronic circuits causes difficulties in integrating electronic circuit-based intelligences.Recent advancement of flexible and stretchable circuits has paved the way for integration of electronics in unusual shapes and forms. Through materials and structure innovation, [7] the circuits become stretchable, deformable, and conformable to curvilinear surfaces, [8][9][10] enabling a spectrum of applications such as stretchable sensors and actuators, [11][12][13][14] transparent conductors, [15,16] lighting, [17][18][19] and energy devices. [20][21][22] Various types of stretchable nanomaterials, such as carbon nanomaterials [23][24][25] and metal nanowires [26][27][28] have been synthesized and integrated to elastomeric polymer matrix for stretchable circuits. Despite their superior mechanical properties and potential to achieve transparent stretchable circuits, so far it has been a struggle to deliver high enough conductivities compared to structure engineered stretchable circuits.Fiber-reinforced polymer composites with integrated intelligence, such as sensors, actuators, and communication capabilities, are desirable as infrastructures for the next generation of "internet of things." However, the shape mismatch between the 3D composites and a planar electronic circuit causes difficulties in integrating electronic circuit-based intelligences. Here, an easily scalable approach, by incorporating a large-area stretchable circuit with thermoforming technology, to fabricate 3D multifunctional composites is reported. The stretchable circuit is first fabricated on a rigid and planar carrier board, then transferred and sandwiched bet...

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Combining stretchable circuits and thermoforming technology, a method to produce 3D multifunctional polymer composites is described by Yang Yang, Jan Vanfleteren, and co‐workers in article number https://doi.org/10.1002/aelm.201800071. A demonstrator consisting of a seven‐segment display with integrated LEDs and capacitive touch sensors is fabricated using the proposed method. The cover image was designed and illustrated by Xiao‐Meng Wu and Dong Tao.

The plating of electroless Ni/Au as a solder for sequential buildup layers is investigated. Advanced Printed Circuit Boards (PCBs) using sequential buildup layers with microvias require alternating dielectric and copper layers. This can be achieved by laminating of RCC, dipcoating of dielectric and deposition of copper or lamination of a polymer layer and deposition of copper. On top of these buildup layers a solder mask polymer has to be applied in order to sperate solder pads. Parts of the underlying buildup layer that are exposed to the electroless Ni plating solution, even though they are etched, can grow electroless Ni on top of them, even though they are not activated by the catalyst. Experiments showed that in the case of RCC this phenomena does not occur, and does occur for the processes that use electroless copper deposition during plating of the buildup layer under the solder mask. Investigation showed that colloidal Pd catalyst remaining from a preceding electroless copper deposition catalyzes the electroless Ni deposition, which uses metallic Pd catalyst. These overplating phenomena could be traced back to the design of the solder mask. All parts Of the buildup layer under the solder mask that require no electroless Ni plating have to be completely covered by solder mask polymer to prevent overplating if the copper layer from the buildup layer was plated This puts more constraints on the fine pitch capability of the solder mask. This is important for the design of the solder mask, because Electroless Ni/Au plating will grow in popularity because of its environment friendliness

This paper deals with an alternative testing approach for quantifying the life time of board level solder joint reliability of components. This approach consists of applying a relative shear displacement between component and Printed Circuit Board (PCB) through cyclic board bending. During the cycling, the temperature is kept constant, preferably at elevated temperature in order to fasten the creep deformation of the solder joint. This is done in a four-point bending setup which allows to apply an equal loading on all components lying between the inner bars. The scope of the paper is, firstly, to evaluate if the four point bending testing generates the same fatigue fracture as in thermal cycling; secondly, that the measured life times can be also predicted through finite element simulations; and thirdly if the technique can finally fasten the cycling frequency to gain testing time.