Why Boric Acid in Nickel Plating?

I am using a solution of Nickel Sulphate, ammonium chloride and boric acid with a nickel electrode, to electroplate nickel onto iron. However I am unsure as to the operation of the Boric acid and Ammonium chloride in the solution. Can you explain and maybe give a general equation for this please?

Thanx,

The boric acid is there to buffer the pH and improve the life expectancy of the bath. I can only presume the ammonium chloride is there to improve electrical conductivity, but I have never come across this formulation in nickel plating. I would expect the deposits to be very stressed as ammonium ions will induce stress. The chloride ions will help the anodic dissolution of the nickel. I would suggest you use either a watts nickel or a sulphamate based nickel, they are much better.