It is important to characterize the bonding force between fiber assemblies in order to produce high-tenacity wet-laid nonwovens. The major technical consideration in making strong bonds are to select good binder fibers and to determine optimum processing conditions. Thus, the effect of bonding conditions, such as bonding temperature, bonding pressure, and bonding angle, on the bonding force produced by two binder fibers (polyester, UHMPE) and two fiber bundles (carbon, glass) was examined. Also, we have considered three breaking modes (i.e., tensile, shear and tear) to evaluate the bonding force between fiber and binder segments. The results obtained in this study are as follows: The bonding forces of carbon/polyester and glass/polyester showed maximum values at bonding temperature of 280 $^{circ}C$. However, those of carbon/UHMPE and glass/UHMPE showed maximum values at 170 $^{circ}C$ and 175 $^{circ}C$, respectively. The maximum bonding force between fiber/binder segments was obtained at a bonding pressure of 30 kgf/$ extrm{cm}^2$ in the case of polyester binder fibers, while in the case of UHMPE maximum bonding force was obtained at a bonding pressure of 70 kgf/$ extrm{cm}^2$. On the experimental condition of bonding angle and breaking mode, the bonding force between fiber and binder had highest value at bonding angle 90$^{circ}$ in the shear mode. These results are provided to assist in designing high-performance wet-laid nonwovens.