The invention provides transient printed circuit board devices, including active and passive devices that electrically and/or physically transform upon application of at least one internal and/or external stimulus.

Biodegradable materials for multilayer transient printed circuit boards

Ultrauniform Embedded Liquid Metal in Sulfur Polymers for Recyclable, Conductive, and Self‐Healable Materials

Conductive plastics are new generation functional materials with potential application in electronics, space and aviation industries. Polypropylene (PP) and polyethylene (PE) being most common, widely available and cheapest thermoplastic, if made conductive, can be revolutionary in the field of engineering thermoplastics. The article deals with the fabrication of electrically conductive PP and PE for electromagnetic interference/radio frequency (EMI/RF) shielding applications and protection against electrostatic discharge (ESD). It reviews different fillers used by researchers to fabricate conductive PP and PE, several factors that affect the electrical conductivity of thermoplastic composites and various processing methods that can be adopted to prepare such composites. It exhaustively covers the preparation of such conductive composites, the processing methods involved therein, and the electrical properties of the end material. Emphasis has been given to comprehend the percolation threshold and means to reduce the latter in order to achieve high electrical conductivity in PP- and PE-based composites at relatively low filler loading. POLYM. COMPOS., 35:900–914, 2014. © 2013 Society of Plastics Engineers

A review on electrically conductive polypropylene and polyethylene

Nanostructured epoxy adhesives: A review

Flexible piezoelectric nano-composite films for kinetic energy harvesting from textiles

Conductive adhesives are widely used in electronic packaging applications such as die attachment and solderless interconnections, component repair, display interconnections, and heat dissipation. The effects of film thickness as functions of filler volume fraction, conductive filler size, shape, as well as uncured adhesive matrix viscosity on the electrical conduction behavior of epoxy-based adhesives are presented in this work. For this purpose, epoxy-based adhesives were prepared using conductive fillers of different size, shape, and types, including Ni powder, flakes, and filaments, Ag powder, and Cu powder. The filaments were 20 μm in diameter, and 160 or 260 μm in length. HCl and H3PO4 acid solutions were used to etch and remove the surface oxide layers from the fillers. The plane resistance of filled adhesive films was measured using the four-point method. In all cases of conductive filler addition, the planar resistivity levels for the composite adhesive films increased when the film thickness was reduced. The shape of resistivity-thickness curves was negative exponential decaying type and was modeled using a mathematical relation. The relationships between the conductive film resistivities and the filler volume fractions were also derived mathematically based on the experimental data. Thus, the effects of surface treatment of filler particles, the type, size, shape of fillers, and the uncured epoxy viscosity could be included empirically by using these mathematical relations based on the experimental data. By utilizing the relations we proposed to model thickness-dependent and volume fraction-dependent conduction behaviors separately, we were able to describe the combined and coupled volume fraction-film thickness relationship mathematically based on our experimental data.

/pdf/electrically-conductive-epoxy-adhesives-4qzge529tj.pdf

Electrically Conductive Epoxy Adhesives

Conductive adhesives are widely used in electronic packaging applications such as die attachment and solderless interconnections, component repair, display interconnections, and heat dissipation. This research intends to provide an understanding of the effects of film thickness as functions of filler volume fraction, conductive filler size, shape, as well as uncured base adhesive viscosity on the electrical conduction behavior of such adhesives. Epoxy-based adhesives were filled with particles of different size, shape, and types, including Ni powder, flakes, and filaments, Ag powder, and Cu powder. The filaments were 20 µm in diameter, and 160 or 260 µm in length. Acid solutions including HCL, H3 PO4 , and HF were used to etch and remove the surface oxide layers. The plane resistance of filled adhesive films was measured using the four-point method. In general, the addition of micron-sized metal fillers to the conductive mixture resulted in distinct thickness thresholds for transition from three-dimensional conductivity to one-dimensional conductivity with considerable increases in plane resistivity when the film thicknesses were smaller than these threshold values. The relationships between the conductive film resistivities and the filler volume fractions were derived mathematically, based on the experimental data. The effects of surface treatment of filler particles, the type, size, shape of fillers, and the uncured epoxy viscosity were also included in this formulation.Copyright © 2003 by ASME

Lan Bai

Papers

Electrically Conductive Epoxy Adhesives

The Effects of Filler Volume Fraction and Film Thickness on Resistivity of Conductive Adhesives