The effects of stress state, loading frequency and cyclic waveforms on the fatigue behavior of silver-filled electronically-conductive adhesive joints

Abstract

Conductive adhesives and filled adhesive systems, in general, are used in a variety of engineering applications. There are a number of issues of concern in the design of joints bonded using electronically conductive adhesives (ECAs) and subjected to cyclic loading. These include the effects of stress state and cyclic parameters (frequency and waveform) of mechanical and/or thermal loading on the fatigue failure behavior of adhesively-bonded joints. In order to study the effects of these parameters on joint behavior, two different joint geometries were designed and tested under a spectrum of fatigue and environmental conditions. The results of our work indicated a profound influence of the stress state and cyclic waveform type on the fatigue strength of the joints. Lowering the cyclic load frequency was also found to reduce the fatigue life of the bonded joints.

Influence of Temperature and Dwelling Time on Low-Cycle Fatigue Characteristic of Isotropic Conductive Adhesive Joint

“…[1][2][3][4][5][6] Interconnects in electronic devices are constantly subjected to temperature variations and thermal strain resulting from differences in the thermal expansion coefficient. Therefore, for electronic devices, the evaluation of the fatigue life of the interconnects is important.…”

Electrically Conductive Epoxy Adhesives

“…In all cases, the resistivity levels are reduced as the volume fraction is increased. In Figures 13-21, the shapes of the resistivity-volume fraction curves are similar and they can be efficiently described by using the 2-parameter power function of Equation 15.…”

“…Obviously, with the lower viscosity of resin 815C, the film resistivity is more sensitive to changes in the filler volume fraction as its exponent, n, is higher at all film thicknesses when nickel flakes are used. We also note that since fractions are used for  values in the Equation 15, the lower values of the exponent n with the higher viscosity resin Epon 830 result in lower film resistivity values, with the effect of the parameter A being much less.…”

“…The processing parameters, such as temperature, pressure, cure time, pot and shelf life are critical to the success of making reliable electrical and mechanical interconnections. A conductive adhesive joint may fail in many different ways [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. These include thermal stresses caused by the coefficient of thermal expansion mismatch between the substrate and component, and by mismatch between the adhesive and adherend during temperature cycling, oxidation of the bonding surfaces and of the filler, and degradation by UV-light or corrosive gases.…”

Yield Behavior of Moderately Filled Epoxy/Ni Suspensions

“…Theoretical and experimental studies have been performed on basic conduction mechanisms [4][5][6][7][8][9], along with studies including the effects of particle size, shape and type [10][11][12][13][14][15]. The behaviors of these adhesives in the bonded form were also studied [12,[14][15][16][17][18][19][20][21][22]. Studies on processing effects included works on the effects of pressure [8,10,15], effects of adhesive film thickness [9,11,14], effects of silver coating [10,11,13], and on anisotropic alignment of nickel particles in magnetic field [13], as well as the work on the possibility of using polyaniline emeraldine salt particles as conductive fillers [23].…”