Nitrogen bubbling has many key effects on electroless gold plating:
Core protective role
It can isolate oxygen in the air, avoid the gold salt and other components in the plating solution from being oxidized and decomposed, greatly improve the stability of the plating solution, reduce the generation of impurities, and avoid pinholes and pitting defects in the plating layer.
Enhanced mass transfer effect
Play the role of mild stirring, so that the plating solution composition distribution is more uniform, improve the consistency of the coating thickness, to avoid the problem of uneven local coating deposition.
Precautions
It is necessary to control the amount of bubbling gas. If the amount of gas is too large, a large number of bubbles in the plating solution will be attached to the surface of the workpiece, which will form defects such as pores and bulges on the plating layer and affect the bonding force of the plating layer.
The core value of nitrogen bubbling is preferentially reflected in the protective effect of oxygen isolation, which cannot be completely replaced by mechanical stirring alone.