Wettability of electroless Ni in the under bump metallurgy with lead free solder

Interfacial reaction and microstructural evolution for electroplated Ni and electroless Ni in the under bump metallurgy with 42Sn58Bi solder during annealing

“…Details of EN deposition were reported elsewhere. 7 In addition, another set of Cu/Al 2 O 3 substrates was plated with the electroplating Ni. The thickness of EN and electroplating Ni was 5~10 mm.…”

Compound formation for electroplated Ni and electroless Ni in the under-bump metallurgy with Sn-58Bi solder during aging

“…For joints of Sn-Bi/Ni-based UBM, previous studies concerning wettability, 11 IMC stripping and dissolving, 12 and metallurgical reaction after annealing 13 have been conducted. The purpose of this study was to investigate the interfacial reaction between eutectic Sn-Bi solder and Ni-based UBMs during aging at 110°C and 130°C and the corresponding microstructural evolution in the joint.…”

Experimental Observation on Solid-State Reactive Diffusion between Sn–Ag Alloys and Ni

“…[1][2][3][4][5][6][7][8] They are Sn-Ag alloys, Sn-Cu alloys, Sn-Ni alloys, Sn-Zn alloys, etc. Among such Sn-base alloys, the Sn-Ag alloy is one of the most favorable candidates of Pb-free solders.…”

“…[9][10][11][12][13][14][15][16][17][18][19][20] On the other hand, owing to high electrical conductivity, Cu-base alloys are widely utilized as conductor materials in the electronics industry. When the Cubase conductor is interconnected with a Sn-base solder, Cu 6 Sn 5 and Cu 3 Sn are formed at the interconnection between the conductor and the solder during soldering and then gradually grow during energization heating at solid-state temperatures. [21][22][23][24][25][26][27][28][29][30][31] Since the Cu-Sn compounds are brittle and possess high electrical resistivities, their growth deteriorates the mechanical and electrical properties of the interconnection.…”

“…To examine this in uence, the kinetics of reactive diffusion in the (Sn-Cu)/Ni system was experimentally observed at temperatures of T = 453-473 K using sandwich (Sn-Cu)/Ni/(Sn-Cu) diffusion couples with Cu mol fractions of 0.01-0.03 prepared by a diffusion bonding technique in a previous study. 37) According to the observation, an intermetallic layer consisting of (Cu,Ni) 6 Sn 5 and Ni 3 Sn 4 is formed at the original interface between the Sn-Cu and Ni specimens in the diffusion couple during annealing. The total thickness of the intermetallic layer increases in proportion to a power function of the annealing time, and the exponent of the power function takes values of 0.37-0.44 at T = 453 K and those of 0.63-0.69 at T = 473 K. Therefore, the growth of the intermetallic layer is controlled by boundary and volume diffusion at T = 453 K. On the other hand, at T = 473 K, interface reaction and interdiffusion contribute to the rate-controlling process of the intermetallic growth.…”