Abstract: The effects of bath composition and deposition conditions on the deposition rate and boron content of the deposit from the bath of citrate-ammonia system have been investigated, The optimum bath composition and deposition conditions are as follows: NiSO₄·7H₂O 40g/l, HB₃O₃ 30g/l, NH₄Cl 30g/l, triammonium citrate 20g/l, dimothylaminoborane (DMAB)4g/l, pH9.5—10, 45℃. The deposit has contact resistance atout 0.126Ω, very close to that of Ag deposit.The XPS and AES results showed that the Ni-B deoosit is composed of Ni₂B alloy and Ni. Ni(Ⅱ) and B(Ⅲ) were found on the surface of the deposit.

Key words: Nickel-boron alloy, Electroless plating, Citrate-ammonia system, Dimethylaminoborane