The interlayer exchange coupling properties in synthetic antiferromagnetic (AF) structures based on Co/Ni perpendicular multilayers were investigated by varying the Ru spacer thickness (tRu) and the ferromagnetic (FM) layer material at the FM/Ru interfaces. Samples of two Co layers adjacent to Ru own much stronger AF coupling field (HAF) and show two HAF peaks located at tRu=0.47 and 1.08nm. If the interfacial Co layers are substituted by Ni, the HAF at the 1st peak decreases much more considerably, becomes lower than the 2nd one and even disappears due to strong pinhole-induced FM coupling. Such pinhole effect makes HAF of tRu<0.85nm remains unchanged or even decrease with decreasing temperatures. By tuning the interfacial Co layer thickness, pinhole effect has been suppressed as a result of greatly enhanced HAF, leading to a normal temperature dependence of Ruderman-Kittel-Kasuya-Yosida-type HAF even at thin tRu cases, i.e., increase in HAF with temperature decreasing.