Properties Of Electrically Conductive Adhesives Research Articles

Simultaneous improvement of the electrical conductivity and mechanical properties via double-bond introduction in the electrically conductive adhesives

For electrically conductive adhesives (ECAs), high electrical conductivity generally conflicts with excellent mechanical properties because electrical conductivity increases while desirable mechanical properties decrease with the increase in loading of conductive fillers or removal of lubricants on the silver filler surface. In this work, a method was developed to improve both the electrical conductivity and mechanical properties of the ECAs by introducing double bonds. Itaconic acid (IA) was used to replace the lubricant on the silver flake (Ag-F) surface, and acrylic acid (AA) was used as part of the ECA resin matrix. IA can replace the lubricant on the Ag-F surface, similar to other short-chain dibasic acids, to improve the ECA electrical conductivity. Furthermore, IA can be polymerized with AA to form covalent bonds between the silver flakes and the resin matrix, enhancing the mechanical properties of ECA. Compared with ECA filled with commercial silver flakes, the electrical conductivity of ECA filled with IA-treated silver flakes increased by ~ 21%, and the lap shear strength increased by ~ 29%.

Self-Assembly Synthesis of Silver Nanowires/Graphene Nanocomposite and Its Effects on the Performance of Electrically Conductive Adhesive.

Among recent advances in electronic packaging technologies, electrically conductive adhesives (ECAs) attract most researchers’ attention, as they are environment-friendly and simple to apply. ECAs also have a lower operating temperature and volume resistivity compared with conventional electronic conductive adhesives. In ECAs, the conducting fillers play a significant role in improving conductivity and strength. In this work, as filler additives, the silver nanowires/graphene nanocomposites (AgNWs-GNs) were successfully fabricated via a facile self-assembly method. The characteristics of the as-prepared nanocomposites were evaluated by FTIR (Fourier Transform infrared spectroscopy), XRD (X-ray Diffraction), XPS (X-ray photoelectron spectroscopy), TEM (Transmission electron microscope) and Raman tests, demonstrating a successful synthesis process. Different amounts of AgNWs-GNs were used as additives in micron flake silver filler, and the effects of AgNWs-GNs on the properties of ECAs were studied. The results suggested that the as-synthesized composites can significantly improve the electrical conductivity and shear strength of ECAs. With 0.8% AgNWs/GNs (AgNWs to GO (Graphite oxide) mass ratio is 4:1), the ECAs have the lowest volume resistivity of 9.31 × 10−5 Ω·cm (95.4% lower than the blank sample without fillers), while with 0.6% AgNWs/GNs (AgNWs to GO mass ratio is 6:1), the ECAs reach the highest shear strength of 14.3 MPa (68.2% higher than the blank sample).

Preparation and Characterization of Purified Multi-Walled Carbon Nanotubes Filled Conductive Adhesive

In this paper, purified multi-walled carbon nanotubes (MWNTs) were obtained by acid treatment and oxidation treatment using the crude MWNTs, then purified MWNTs were filled into acrylate pressure-sensitive adhesive (PSA) to produce electrically conductive adhesives (ECAs). XRD and TEM results showed that the impurities were greatly eliminated after purification treatment. The electrical conductivity of the ECAs increased gradually as the content of the purified MWNTs increased. When the content of the purified MWNTs is 4.0vol%, the properties of ECAs are optimum.

PROPERTIES OF CONDUCTIVE ADHESIVES BASED ON DIFFERENT CURING AGENTS

Electrically conductive adhesives (ECAs) are an environmentally friendly alternative for traditional tin/lead (Sn/Pb) solders. As a new technology, conductive adhesive technology still has many concerns and limitations. In order that conductive adhesive technology achieves universal acceptance, ECAs with better properties must be developed. ECAs consist of a polymeric matrix and a conductive filler. Compositions of the polymeric matrix play a very important role in determining the overall properties of ECAs. The objective of this study is to investigate the effects of different curing agents on the properties, especially contact resistance of conductive adhesives. Five polymeric matrix formulations are prepared by mixing five different curing agents, selected from different categories, with an epoxy resin. Using these polymeric matrix formulations, five ECAs are formulated. The properties of these ECAs studied include: curing profile, glass transition temperature (Tg), coefficient of thermal expansion (CTE), moisture absorption, adhesion strength, and shifts of contact resistance of these ECAs on non-noble metals such as tin, tin/lead, and copper, during elevated temperature and humidity aging. Also, a corrosion inhibitor is used to stabilize contact resistance of these ECAs on Sn/Pb. It is found that (1) the curing agents do affect the properties including contact resistance of ECAs and (2) the corrosion inhibitor is effective to stabilize contact resistance on Sn/Pb in all of the five ECA formulations.

A study of lubricants on silver flakes for microelectronics conductive adhesives

Conductive adhesives are composites of polymer matrixes and metal fillers (conductive elements). Silver (Ag) flakes are widely used as fillers for electrically conductive adhesives (ECAs). Generally, there is a thin layer of organic lubricant coated on the commercial Ag flake surface. This lubricant layer is needed for eliminating the Ag particle agglomeration while dispersing the Ag filler into the polymeric resin. Therefore the lubricant influences rheology, conductivity, and other properties of ECA's. The nature of the lubricant on a Ag flake and the interaction between the lubricant and the Ag flake surface were studied by diffuse reflectance infrared spectroscopy (DRIR). Thermal decomposition of the lubricant was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In addition, the effects of some chemical compounds on lubricant removal and the enhancement of conductivity of the ECA were also investigated. It was found that 1) a chemical bonding was formed on the Ag flake surface between the lubricant and Ag; 2) the short chain acids replaced the long chain lubricants; 3) an ether and a poly(ethylene glycol) enhanced electrical conductivity by partially removing the Ag flake lubricants.