To experimentally detect solder residue on the PCB, the following methods can be used:
1. Visual observation: Use a magnifying glass or optical microscope to observe the PCB board and pay attention to whether there are solid residues of flux, tin slag, tin beads, unfixed metal particles and other contaminants. If the PCB surface is required to be very clean, there should be no traces of residue or contaminants visible.
2. Anion and cation test: Analyze the degree of pollution through the types and contents of anions and cations and organic acids. Test results are generally expressed in ug/cm2. The advantage of this method is that the residual species and content of each ion can be understood in great detail.
The above methods are for reference only. It is recommended to consult professionals for more information.