Resistance and Nonlinearity of Current-Voltage Characteristic of Conductive Adhesive Joints with Isotropic Conductivity: Tunnel Theory

Electrical conductivity of electrically conductive adhesives is the most significant parameter these environmental friendly materials for adhesive assembly in electronics. Electrical conductivity of influenced by two types of resistances: by the constriction resistance and by the tunnel one. If adhesives with isotropic electrical conductivity are used for assembly, the tunnel resistance dominates in the total value of the resistance of an adhesive joint. Therefore, the adhesion joint is seen as an aggregate tunnel junction. The theory of conductivity of this junction emerges from the theoretical description of the tunnel phenomenon. Dependence of the tunnel junction resistance on the thickness of the insulating barrier is presented. Measurement of nonlinearity of the I-V characteristic of the tunnel junction is described as well. The results of this measurement make it possible to find the constant needed in the formula for calculating the joint resistance.