Recent achievements and performance of nanomaterials in microwave absorption and electromagnetic shielding.

Due to the swift advancement of the electronic industry and information technology, electromagnetic wave absorption materials are gaining significance in the field of intelligent equipment and weaponry. Nanomaterials were developed to investigate wave absorbing materials that can achieve both impedance matching and attenuation balance. Nanomaterials possess the properties of being thin, lightweight, and capable of absorbing microwave radiation across a wide range of frequencies.

FPCB as an Acoustic Matching Layer for 1D Linear Ultrasound Transducer Arrays.

An acoustic matching layer is an essential component of an ultrasound transducer to achieve maximum ultrasound transmission efficiency. Here, we develop a flexible printed circuit board (FPCB) with a composite structure consisting of multiple polyimide and copper layers and demonstrate it as a novel acoustic matching layer. With a flexible substrate and robust ACF bonding, the FPCB not only serves as an acoustic matching layer between piezoelectric elements and the surrounding medium but also as a ground for the electrical connection between the transducer array elements and the folded substrate.

Acoustic Matching Layer Films Using B-Stage Thermosetting Polymer Resins for Ultrasound Transducer Applications.

Acoustic matching layer films (MLFs) were fabricated using B-stage thermosetting polymer resins with various volume fractions of alumina and tungsten powders. After making certain thickness MLFs, ultrasonic matching layers were fabricated using a simple molding process. The thickness of the matching layers can be precisely adjusted from several micrometer to hundreds of micrometer, without any grinding process.

Ultrathin Nanofibrous Membranes Containing Insulating Microbeads for Highly Sensitive Flexible Pressure Sensors.

Highly sensitive and flexible pressure sensors were developed based on dielectric membranes composed of insulating microbeads contained within polyvinylidene fluoride (PVDF) nanofibers. The membrane is fabricated using a simple electrospinning process. The presence of the microbeads enhances porosity, which in turn enhances the sensitivity (1.

IMCs Microstructure Evolution Dependence of Mechanical Properties for Ni/Sn/Ni Micro Solder-Joints.

The current miniaturization trend of microelectronic devices drives the size of solder joints to continually scale down. The miniaturized joints considerably increase intermetallic compounds (IMCs) volume fraction to trigger mechanical reliability issues. This study investigated precise relationships between varying IMC volumes and mechanical properties of Ni/Sn(20μm)/Ni micro-joints.

Direct Visualization of Cross-Sectional Strain Distribution in Flexible Devices.

For flexible devices that inevitably undergo repetitive deformations, it is important to evaluate and control the mechanical strain imposed on the flexible systems for enhancing the reliability. In this paper, a novel experimental method to directly visualize cross-sectional strain distribution in the thin flexible devices is proposed. Digital image correlation (DIC) is effectively adapted by using microscopic images of the cross section for accurate analysis of the microscale deformations.

Effects of nanofiber on the electrical properties of anisotropic conductive adhesives (ACAs).

The effects of nanofiber on the electrical properties of anisotropic conductive films (ACFs) were investigated from the perspectives of the joint and insulation resistances. To obtain stable electrical properties for fine-pitch chip-on-film (COF) packages, two kinds of nanofiber ACFs were demonstrated: (1) polystyrene (PS) and polyacrylonitrile (PAN) nanofiber ACFs, which were formed by laminating ACFs on the top and bottom sides of PS and PAN nanofibers, and (2) PAN nanofiber coupled with conductive particle (PAN/Cp nanofiber) ACF, which was made by laminating non conductive films (NCFs) on both sides of a PAN/Cp nanofiber. The effects of the nanofiber thickness, melting, and structure on the electrical properties of the nanofiber ACFs were analyzed.

Enhanced thermal conductivity of epoxy-graphene composites by using non-oxidized graphene flakes with non-covalent functionalization.

Homogeneous distribution of graphene flakes in a polymer matrix, still preserving intrinsic material properties, is key to successful composite applications. A novel approach is presented to disperse non-oxidized graphene flakes with non-covalent functionalization of 1-pyrenebutyric acid and to fabricate nanocomposites with outstanding thermal conductivity (∼1.53 W/mK) and mechanical properties (∼1.

Enhanced electrical conductivity of nanocomposites containing hybrid fillers of carbon nanotubes and carbon black.

Nanocomposites reinforced with hybrid fillers of carbon nanotubes (CNTs) and carbon black (CB) are developed, aiming at enhancing the electrical conductivity of composites with balanced mechanical properties while lowering the cost of the final product. Epoxy-based nanocomposites were prepared with varying combinations of CNTs and CB as conducting fillers, and their electrical and mechanical properties were evaluated. It was shown that the addition of CNTs in CB composites enhanced the electrical conductivity of composites: a low percolation threshold was achieved with 0.