NH4F对化学镀镍液的作用机理及镀层性能的影响

氟元素是周期表中最活泼的非金属元素,有着最强的电负性,氟化物有着特殊的化学性能。关于氟化物在化学镀镍磷工艺中的应用已有报道,在镁基体上化学镀的前处理过程中,常用氢氟酸或氟化氢铵来进行活化处理;硅片表面上的化学镀也通常用HF与HNO3或HCl的混酸来活化,使硅片表面产生Si-H键。另外,如果在化学镀液中添加少量的氟化钠,则起到加速的作用[1]。对于氟化物在化学镀镍磷工艺中的报道仅限于此,未见有关氟化物在化学镀中其它作用的研究。鉴于此,本工作以氟化铵为研究对象,对其在弱碱性的条件下对化学镀液的缓冲能力、沉积速度以及所得镀层性能的影响进行了研究。

Effects of NH4F on Electroless Ni-P Plating Bath and Properties of Coatings

The deposition rate and buffering capability of electroless Ni-P plating were studied by ammonium fluoride addition. SEM images show that the coating surface is finer when ammonium fluoride is added in the bath. The electrochemical measurements show that the corrosion resistance of the Ni-P coatings from the bath with ammonium fluoride is greatly improved. EDS shows that the distribution of phosphorus of the coating from the bath with ammonium fluoride is much more uniform than the coating from the original bath, and the surface microhardness is also improved. Ammonium fluoride is proved to be an excellent buffering agent.