Effect of different types of silver and epoxy systems on the properties of silver/epoxy conductive adhesives (original) (raw)
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Electrically conductive adhesive filled with mixture of silver nano and microparticles
2008
Electrically conductive adhesive with isotropical electrical conductivity modified with addition of silver nanoparticles has been investigated. The electrical resistance, nonlinearity of a current vs. voltage characteristic and the tensile strength of adhesive joints formed of this adhesive have been measured. The specimens have also been aged at the temperature of 125°C and at the combined climate 80°C/80 % relative humidity for 700 hours. It has been found that silver nanoparticles added into the electrically conductive adhesive cause decrease of its conductivity, increase of its nonlinearity and increase of the tensile strength.
Polymer, 2016
Diglycidyl ethers of bisphenol-A (DGEBA)/4,4 0 -diaminodiphenylmethane (DDM)/polyethersulphone (PES) blends were prepared as matrix resins for electrically conductive adhesives containing silver (Ag) fillers. The epoxy/PES blends formed co-continuous phase structures from initial homogeneous solutions via reaction-induced phase separation during the curing process. The Ag fillers were selectively localized in the epoxy-rich phases that had high affinity toward the surface of the Ag fillers. The co-continuous phase structures of the epoxy/PES blends acted as templates for the three-dimensional continuous structures of the Ag fillers. The self-assembled structures of the Ag fillers were connected in a continuous phase that possessed high electrical conductivity using a relatively small amount of Ag filler. In addition, the epoxy/PES/Ag adhesives had excellent shear adhesive strength. The fracture toughness of the epoxy/ PES blends was the source of the high adhesive strength.
Synthetic Metals, 2004
Electrical conductivity and percolation concentrations of epoxy and polyurethane (PU) resins filled with Ag-coated particles and short fibers were studied in this paper. Percolation concentrations were determined to be as follows: 29 vol.% for epoxy/Ag-coated fibers and PU/Ag-coated particles and fibers and 28 vol.% for epoxy/Ag-coated particles. The highest values of electrical conductivity were found for PU/Ag-coated fibers.
Modification of electrically conductive adhesives for better mechanical and electrical properties
2008 31st International Spring Seminar on Electronics Technology, 2008
The goal of the work has been to check a possibility of improvement of electrical properties of electrically conductive adhesives with isotropic electrical conductivity to edge these properties toward to properties of solders. The electrical resistance and nonlinearity of I-V characteristic have been investigated. Two ways have been used for electrically conductive adhesive modification: addition of small amount of silver nanoparticles (grains) of three different dimensions into adhesive, and substitution of a part of filler flakes with the same amount of nanoparticles. It has been found that addition of silver nanoparticles increases the resistance and nonlinearity of adhesive. It has also been found that adhesives modified with nanoparticles have lower sensitivity to combined climatic ageing in comparison with adhesives without nanoparticles. The reason is other quality of contacts between flakes and contacts between nanoparticles.
Testing of techniques for improvement of conductivity of electrically conductive adhesives
2008 2nd Electronics Systemintegration Technology Conference, 2008
The paper presents methods, which have been used for improvement of electrical conductivity of electrically conductive adhesives with isotropical electrical conductivity. Conductivity level depends, among other things, on level of aggregation of filler particles. The research has been focused on improvement of electrical properties by better aggregation of filler particles in adhesive. Following methods have been tested with the goal to support aggregation: ultrasound mixing for 60s, rotary mixing for 60 s, and addition of a small amount of AgN0 3. The goal of addition of this salt has been to decrease Coulomb forces between particles of filler. Four types of formulations have been used for experiments. One-component formulations: adhesives bisphenol epoxy resin with 75 % (wt.) silver flakes, bisphenol epoxy resin with 75 % (wt.) silver flakes + 10 % (wt.) silver nanoparticles, bisphenol epoxy resin with 65 % (wt.) silver flakes + 20 % (wt.) silver nanoparticles. Two component formulation: bisphenol epoxy resin with 55 % (wt.) silver flakes. It has been found that ultrasound mixing has low influence only to the value of the electrical conductivity of adhesive, rotary mixing before application of the adhesive improves electrical conductivity significantly; addition of AgN0 3 into the adhesive has improved electrical conductivity of two formulations and has had almost no effect for two other formulations. As a part of this work the course of electrical conductivity of adhesives during the curing time has also been investigated.
Journal of Materials Science: Materials in Electronics, 2014
Electrically conductive adhesives (ECAs) filled with silver nanoparticle (Ag NP)-decorated graphene were prepared and the effect of curing temperature on the electrical conductivity of the ECAs was discussed. Mono-dispersed Ag NPs with an average size of 9 nm were successfully deposited and simultaneously functionalized with mercaptopropionic acid (MPA) on graphene surface. The surface functionalization of the NPs with MPA made the decorated graphene dispersible in organic solvents, which facilitated its dispersion inside epoxy. The decorated graphene was added into conventional ECAs (consisting of silver flakes and epoxy) at concentrations close to the percolation threshold and beyond that resulting in a significant electrical conductivity improvement (especially at concentrations close to the percolation threshold). The electrical resistivity of hybrid ECAs with the decorated graphene decreased as the curing temperature increased. Curing the ECA with 1 wt% of the decorated graphene at 220°C resulted in a highly conductive adhesive with a low electrical resistivity of 4.6 9 10-5 X cm (close to that of eutectic lead based solders). The dramatic electrical conductivity improvement of ECAs is due to the sintering between small Ag NPs on the graphene surface and silver flakes. Morphological and thermal studies showed that Ag NPs start to sinter at approximately 150°C when the MPA layer began to decompose from their surface. The quality of filler-filler interaction was investigated by monitoring the effect of temperature on the electrical resistivity of conductive fillers ''thin-film'' before their addition to epoxy.
EFFECTS OF POLYANILINE FILLER ON THE SHEAR STRENGTH OF SILVER-POLYANILINE-EPOXY ADHESIVE
Electrically Conductive Adhesives (ECAs) are widely applied in electronic packaging such as solder less interconnections, heat dissipation and component repair. This research focuses on the effects of polyaniline filler percentage in the silver-polyaniline epoxy conductive adhesive. Conductive adhesives with different polyaniline filler concentrations were prepared, so as to check on how the different filler concentrations affect the shear strength of the ECAs. Silver concentration was kept constant, but the polyaniline concentration was varied between 3-10%. The shear strength of the adhesive was measured using the universal tensile machine and the results showed that, more the filler loading is increased, less the adhesive strength exhibited by the composite. The research also shows the synthesis of the main filler silver particles by chemical reduction method and also the synthesis of the co-filler polyaniline by chemical method and both UV (Ultraviolet) and SEM (Scanning Electron Microscope) characterizations were conducted. Keywords: Electrically Conductive Adhesives, Filler Loading, Silver Particles, Polyaniline Particles, Shear Strength
Journal of The Electrochemical Society, 2014
Silver-plated graphite powder, poly(3,4-ethylenedioxythiolphene):poly(styrenesulfonate) (PEDOT:PSS), and organic additives were employed to reduce the electrical resistivities of epoxy-based adhesives. A novel silver self-activated electroless deposition using conductive graphite particles as filler in electrically conductive adhesives (ECAs) was investigated to develop high-performance ECAs with low silver content. Adding silver-plated graphite powders to the conductive adhesives reduced their electrical resistivities by at least two orders of magnitude compared with those filled with graphite powders only. The silver content of the adhesive with PEDOT:PSS decreased to 24.7 wt%, and its resistivity was 1.2 × 10 −3 cm. The best electrical resistivity of the epoxy-based conductive adhesives with 70 wt% silver-plated graphite powders was 4.36 × 10 −4 cm. The weight percentage of silver in this epoxy-based adhesive decreased to 43.3 wt%, which is much lower than that of conventional silver conductive adhesives.
Journal of Applied Polymer Science, 2014
In this study, a dual-microcapsule epoxy-amine self-healing concept is used for electrically conductive adhesives (ECAs). It provides the ECA samples with the ability to recover mechanical and electrical properties automatically. Epoxy and amine microcapsules were prepared and incorporated into silver/epoxy ECAs. The healing efficiency and bulk resistivity of the undamaged, damaged, and healed specimens were measured, respectively. The optimal loading of the epoxy and amine microcapsules is 6 wt % (weight ratio 1.05), and the bulk resistivity of the healed specimens is 3.4 3 10 23 X cm.
2011
Epoxy composites filled with nano-and microsized silver (Ag) particulate fillers were prepared and characterized based on flexural properties, coefficient of thermal expansion, dynamic mechanical analysis, electrical conductivity, and morphological properties. The influences of these two types of Ag fillers, especially in terms of their sizes and shapes, were investigated. Silver nanoparticles were nano-sized and spherical, while silver flakes were micron-sized and flaky. It was found that the flexural strength of the epoxy composite filled with silver flakes decreased, while the flexural strength of the epoxy composite filled with silver nanoparticles showed an optimum value at 4 vol.% before it subsequently dropped. Both silver composites showed improvement in flexural modulus with increasing filler loads. CTE value indicated significant decrements in filled samples compared to neat epoxy. Results on the electrical conductivity of both systems showed a transition from insulation to conduction at 6 vol.%.