The main purpose is to get rid of the pollution of copper oxide, fingerprint, grease and so on, which may appear in the prefabrication process, so as to get clean copper surface.
Micro-etch (microetch) :
The main purpose of microetching is to remove serious oxides on copper surface and to produce uniformly bright and slightly rough copper surface, so that the subsequent OSP skin can be longer and more uniform.Generally, there is a positive correlation between the color of the copper surface after OSP film formation and the selected microetching solution, because different chemicals will cause different roughness of the copper surface.
The function of pickling is to thoroughly remove the residue on the copper surface after microetching to ensure that the copper surface is clean.
OSP coating (organic protective flux treatment) :
The copper surface is covered with a layer of organic copper compounds to protect the copper surface from oxidation during storage.Generally, OSP film thickness is required between 0.2-0.5um.
The factors affecting OSP film formation are:
Let's take the pH of that OSP tank
The concentration of OSP solution
The total acidity of the OSP solution
Main operating temperature
Washing after OSP should strictly control the ph value above pH2.1 to avoid excessive acid washing to dissolve the OSP skin film, resulting in insufficient thickness.