Characterization of anisotropic conducting adhesive used as a flex-to-card interconnection

Analysis of the Constriction Resistance in an ACF Bond

“…If we extend Whitley's expansion to fifth order and convert to the formula for the constriction resistance of just one half-space, then the following equation is obtained: (7) where is the Lorentz number 2.44 10 V K and is the resistance at ambient temperature . Thus, a plot of the measured resistance versus should be a straight line if the term is negligible, which was found to be true [15], [17]. The numerical result from (7) is the same as the results listed in the first row of Table I, and was used as a check on the numerical solution.…”

“…The resistance of this bond is 0.007 , whereas the measured resistance for such a bond would be about an order of magnitude larger. For example, the averaged measured resistance for a much larger 0.41-mm bond was 0.06 , and the minimum measured resistance was 0.031 [26]. Polymer particles yield even larger resistances, on the order of an ohm, which totally overwhelms the constriction resistance calculated by Fu et al for adjacent particles or particles on the edge of the pad.…”

“…The experimentally measured quantity is the bond resistance which can be found from the above power series using the fact the and . Making these substitutions, the above power series expression for the potential becomes (6) Experimental data was well described by the first two terms of this expression [15], [17].…”

“…This work and subsequent work [15], [17] have shown that the effective diameter of contact points, or a-spots, is smaller than 1 m. Under the circumstance where the a-spot radius is much smaller than the thickness and width of the conductor underlying contact a-spot, the usual constriction resistance formula given below may be used [18] (1)…”

“…For the study by Prabhakumar et al [17], Sony Chemical CP 7351KS ACF was used, which had gold-coated solid nickel particles having a diameter of about 7.5 m. The typical apparent area of contact was 11 m . As mentioned above the average resistance for bonds using solid nickel particles was 0.06 with an average of 55 particles.…”