High bonding temperature and force are known to cause physical damage to the device. The objective of this present study is to develop a new low-temperature and pressureless bonding method for Cu-to-Cu interconnects using electroless Ni plating. Two plating methods were employed to test the feasibility of electroless bonding of copper pillars. The first method was carried out in a stirred plating bath with a stirred rate of 500 rpm with and without surfactant additives. The second method was performed in a microfluidic fixture, in which the plating solution was directly pumping into the test vehicles. Preliminary results show that a seam-free bonding joint of dome-shaped copper pillars could be obtained with the use of the microfluidic fixture, while a continuous seam was observed after bonding in a stirred bath with the addition of Triton X-100. In addition, an elongated disc-shaped void was present in the flat-topped copper pillars after bonding in both methods.